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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 10 (1972), S. 82-90 
    ISSN: 1432-0827
    Schlagwort(e): Calcium ; Phosphate ; Precipitation ; Kinetics ; Chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé La cinétique de la formation et de la transformation des précipités de phosphate de calcium, obtenus en mélangeant de volumes égaux de solutions à 6×10−3 M de calcium total et/ou phosphate total est étudiée à 25°C. Les solutions de phosphate sont préajustées à un pH de 7.4. Les changements de pH et de turbidité des solutions sont suivis simultanément en fonction du temps. Les précipités sont isolés à des intervalles de temps variables et caractérisés par diverses méthodes physico-chimiques. Initialement un précipité avec un rapport molaire Ca/P de 1.5, amorphe aux rayons X et en diffraction électronique, est formé. Le spectre IR indique la présence de PO 4 3− et de HPO 4 2− . Après une période métastable, on observe la précipitation d'un matériel cristallin dans ou sur la phase amorphe. Vingt quatre heures après préparation de l'échantillon les précipités présentent surtout les caractères du phosphate octocalcique.
    Kurzfassung: Zusammenfassung Die Kinetik der Bildung und Transformation von Calciumphosphat-Niederschlägen wurde bei 25°C untersucht. Es wurden dazu gleiche Volumen von Lösungen gemischt, bei einer Konzentration von 6×10−3M totales Calcium und/oder totales Phosphat. Die Phosphatlösungen wurden zuerst auf pH 7,4 eingestellt. Veränderungen des pH und Trübung der Lösungen wurden gleichzeitig als eine Funktion der Zeit aufgezeichnet. Niederschläge wurden in verschiedenen Zeitintervallen isoliert und mit verschiedenen physiko-chemischen Methoden charakterisiert. Am Anfang wurde ein Niederschlag mit einem molaren Ca/P-Verhältnis von 1,5, im Röntgenbild und in der Elektronendiffraktion amorph, gebildet. Infrarotspektren deuteten die Anwesenheit von PO 4 3− - und HPO 4 2− -Ionen an. Nach einer metastabilen Periode erfolgte ein Niederschlag aus kristallinem Material innerhalb oder auf der amorphen Substanz. 24 Std nach der Herstellung der Proben zeigten die Niederschläge in der Hauptsache die Charakteristiken von Octocalciumphosphat.
    Notizen: Abstract The kinetics of the formation and transformation of calcium phosphate precipitates obtained by mixing equal volumes of solutions, 6×10−3 M in total calcium and/or total phosphate was investigated at 25°. The phosphate solutions were preadjusted to pH 7.4. Changes of the pH and turbidity of the solutions were followed simultaneously as a function of time. Precipitates were isolated at various time intervals and characterized by different physicochemical methods. Initially a precipitate with a molar Ca/P ratio of 1.5, amorphous to X-ray and electron diffraction was formed. IR spectra indicated the presence of PO 4 3− and HPO 4 2− ions. After a period of metastability, precipitation of a crystalline material within or upon the amorphous matter occurred. Twenty four hours after sample preparation the precipitates showed mainly the characteristics of octacalcium phosphate.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 16 (1974), S. 145-152 
    ISSN: 1432-0827
    Schlagwort(e): EHDP ; Bone ; Chemistry ; Serum ; Rabbits
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract The effects of disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) on bone and serum chemistry were investigated in adult rabbits. EHDP was administered by subcutaneous injection at doses of 0.25, 2.5 and 10 mg/kg body weight/day for of 28 days. Blood samples were obtained weekly from each rabbit and serum levels of total calcium, ionized calcium, inorganic phosphate and alkaline phosphatase were determined. At the end of the treatment period all rabbits were sacrificed and the tibiae removed for chemical analysis and histological evaluation. The effect of EHDP administration on serum chemistry was both dose- and time-related. The highest of the three doses, 10 mg/kg/day, resulted in a time-related decrease in total serum calcium. This dose also caused a rapid but transient reduction in serum ionized calcium. The effect of EHDP on serum inorganic phosphate was biphasic. Administration of 2.5 mg/kg/day resulted in a time-related elevation in this parameter, whereas the 10 mg/kg/day dose resulted in a time-related hypophosphatemic response. There were no significant drug-related changes in tibial fat-free dry weight, ash weight, total calcium or total phosphorus values. However, administration of 2.5 and 10 mg/kg/day EHDP resulted in increased osteoid tissue as measured histologically. These results are compared with data from other EHDP studies, and discussed in relation to the maturity and growth-state of the experimental animals.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 23 (1977), S. 13-17 
    ISSN: 1432-0827
    Schlagwort(e): Dental calculus ; Glycopeptide ; Chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary A method is described for the isolation and purification of a sulphated glycopeptide from human supragingival calculus. The compound was isolated after using EDTA treatment, 2 M CaCl2 extraction, proteolytic digestion, ethanol precipitation, and finally purified by DEAE cellulose chromatography. It migrated as a single component on cellulose acetate electrophoresis, and chemical and infrared spectral analysis showed the presence of covalently attached sulphate groups. The sulphated glycopeptide was distinguished from being a sulphated glycosaminoglycan.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    ISSN: 1432-0975
    Schlagwort(e): Key words Otolith ; Chemistry ; ICP-MS ; Stock discrimination ; Epinephelus striatus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie
    Notizen: Abstract  We examined the utility of otolith minor and trace element chemistry, assayed with inductively coupled plasma mass spectrometry (ICP-MS), as a means of delineating population structure in the Nassau grouper (Epinephelus striatus). We characterized the elemental composition of otoliths collected in 1993 from three locations in Exuma Sound, Bahamas and from Glover Reef, Belize in 1995. A single location in Exuma Sound was sampled in 1994 to test temporal variability in otolith composition. Five elements (Ca, Zn, Sr, Ba and Pb) were routinely detected, at levels significantly above background, by solution-based ICP-MS. Results from analysis of variance of elemental data, expressed as a ratio to Ca, indicated that there were no significant differences among the Exuma locations for any element, but significant variability was found between Glover Reef and the pooled Exuma localities for Zn/Ca, Sr/Ca and Ba/Ca ratios. Significant inter-annual differences at one Exuma Sound location was restricted to Ba/Ca ratios. Discriminant function analysis correctly classified 86% and 95% of the Belize and pooled Exuma sites, respectively. Otoliths from Belize were characterized by low Zn/Ca and high Ba/Ca and Pb/Ca ratios compared to otoliths from fish collected in Exuma Sound. Although differences in Ba levels may be related to upwelling at Glover Reef, more data are needed to definitely link otolith composition with regional differences in water chemistry.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 15 (1980), S. 79-101 
    ISSN: 1432-1432
    Schlagwort(e): Molecules ; Interstellar ; Chemistry ; Isotopes ; Solar system
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The study of interstellar molecules broadly includes two areas of interest. One area uses the unique ability of molecules to act as probes of the physical conditions in the cold, dense, visually opaque component of the interstellar medium. The physical properties of this and other components of the interstellar medium are summarized. The other area deals with the chemistry of interstellar molecules, recent aspects of which are emphasized in this review. Gas-phase chemistry, shock chemistry, and grain surface chemistry are discussed in the context of recent observations. No present observations suggest that surface reactions are relevant, but neither can they be ruled out. Ion-molecule reactions are clearly operative, at least for the simpler species. Chemical isotope fractionation is reviewed, andd it is concluded that the complexities of the chemistry allow no cosmological conclusions to be drawn from observations of deuterium in interstellar molecules, while the presence of13C in interstellar molecules permits an estimate of the12C/13C ratio which is consistent with the current concepts of the nucleosynthesis history of the Galaxy. Possible connections between interstellar molecules and the early molecular history of the solar system are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Pure and applied geophysics 118 (1980), S. 128-151 
    ISSN: 1420-9136
    Schlagwort(e): Galactic cosmic rays ; Solar proton events ; Particle precipitation ; Chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract An assessment is made of the relative contribution of certain classes of energetic particle precipitation to the chemical composition of the middle atmosphere with emphasis placed on the production of odd nitrogen and odd hydrogen species and their subsequent role in the catalytic removal of ozone. Galactic cosmic radiation is an important source of odd nitrogen in the lower stratosphere but since the peak energy deposition occurs below the region where catalytic removal of O3 is most effective, it is questionable whether this mechanism is important in the overall terrestrial ozone budget. The precipitation of energetic solar protons can periodically produce dramatic enhancement in upper stratospheric NO. The long residence time of NO in this region of the atmosphere, where catalytic interaction with O3 is also most effective, mandates that this mechanism be included in future modelling of the global distribution of O3. Throughout the mesosphere the precipitation of energetic electrons from the outer radiation belt (60°≲Λ≲70°) can sporadically act as a major local source of odd hydrogen and odd nitrogen leading to observable O3 depletion. Future satellite studies should be directed at simultaneously measuring the precipitation flux and the concomitant atmosphere modification, and these results should be employed to develop more sophisticated models of this important coupling.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Aquatic sciences 51 (1989), S. 108-128 
    ISSN: 1420-9055
    Schlagwort(e): Chemistry ; mountain lakes ; silica ; acidity ; sediment
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Alpine lakes in siliceous catchments of Tyrol and Carinthia (Austria) show signs of acidification. About 9% of the studied lakes have no alkalinity, more than 20% are below pH 6. About two thirds of all lakes have acid neutralizing capacities below 100 μeq 1−1. In spite of moderate precipitation acidity, some lakes show considerable concentrations of dissolved reactive aluminum during or shortly after snowmelt. High altitude lakes of the Alps are definitely more acidic than high mountain lakes in remote areas. Large differences in water and soil chemistry of nearby situated lakes were attributed to heterogeneities of bedrock geology. Paleolimnological investigations on former pH values of five lakes, based on diatom assemblages in the sediment, showed different developments: recent and past acidification, stable conditions, and alkalinization.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Accreditation and quality assurance 5 (2000), S. 409-413 
    ISSN: 1432-0517
    Schlagwort(e): Key words Metrology ; Comparisons ; Chemistry ; Standards
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract  After stressing the importance in the modern world of accurate and reproducible measurements, the actions taken by the Bureau International des Poids et Mesures to set up, together with the regional metrology organizations, a series of key comparisons are described. They are the technical foundation of a mutual recognition of national measurement standards arrangement prepared in conjunction with the National Metrology Institutes (NMIs). This arrangement also includes the recognition of calibration and measurement certificates issued by these institutes. Then, the consequences of this arrangement for trade are described. The case of chemical analysis is illustrated by the application of the Kyoto protocol on the reduction of greenhouse gases. But the global workload to be taken up by the International Committee of Weights and Measures, its Consultative Committee for Amount of Substance and the NMIs is huge.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 14 (1974), S. 3-14 
    ISSN: 1432-0827
    Schlagwort(e): Hydroxyapatite ; Mineral ; Phase ; Chemistry ; Synthesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé Des diagrammes de phase d'équilibre ont été déterminés pour le système CaO-P2O5-H2O en utilisant des techniques de synthèse hydrothermique au cours de variatio nsde température allant de 300–600° et 2 Kb H2O de pression. De l'hydroxyapatite bien cristallisé a été synthétisé et caractérisé. De faibles variations de paramètres de la maille cristalline, liées à la température de synthèse et composition globale du matériel initial, ont été déterminées. Des conditions chimiques précises sont nécessaires pour obtenir de l'apatite, en tant que seule phase solide en équilibre dans la solution. Les résultats de diagramme de phase d'équilibre sont comparés avec ceux obtenus dans des milieux synthétiques.
    Kurzfassung: Zusammenfassung Es wurden Gleichgewichts-Phasendiagramme für das System CaO-P2O5-H2O bestimmt, indem hydrothermale Synthese-Techniken im Temperaturbereich von 300–600° und bei einem Druck von 2 Kb H2O verwendet wurden. Es wurde gut-kristallisiertes Hydroxyapatit erzeugt und charakterisiert. Es wurden geringe Unterschiede in den Parametern der Zelleinheiten festgestellt, welche von der angewandten Temperatur und der Zusammensetzung des Startmaterials abhingen. Es waren genaue chemische Bedingungen nötig, um Apatit als die einzige feste Phase im Gleichgewicht mit der Lösung zu erhalten. Die Resultate der Gleichgewichts-Phasendiagramme werden mit früheren Untersuchungen mit der Synthesetechnik verglichen.
    Notizen: Abstract Equilibrium phase diagrams have been determined for the system CaO-P2O5-H2 using hydrothermal synthesis techniques in the temperature range 300–600° and 2 Kb H2O pressure. Well-crystallized hydroxyapatite has been produced and characterized. Small variations in unit cell parameters dependent on temperature of synthesis and bulk composition of the starting materials have been determined. Precise chemical conditions were required to obtain apatite as the only solid phase in equilibrium with solution. Equilibrium phase diagram results are compared with previous synthetic investigations.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 7 (1971), S. 150-162 
    ISSN: 1432-0827
    Schlagwort(e): Uranium ; Bone ; Distribution ; Fission ; Chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé Une concentration moyenne de 2.4×10−8 g U/g de cendre a été obtenue à partir de l'os humain normal. La microdistribution de l'uranium dans l'os indique que cet élément est surtout limité à surface de l'endoste et, en particulier, aux surfaces de l'os lamellaire et aux parois des canaux de Havers, ouverts dans l'os corticol. Cette répartition suggère que l'uranium se présente sous une forme chimique impropre à son incorporation dans l'apatite osseux: il ne semble donc pas exister une distribution diffuse significative de l'uranium dans l'os.
    Kurzfassung: Zusammenfassung Eine mittlere Konzentration von 2,4×10−8 g Uran/g Asche wurde in normalen menschlichen Knochen gefunden. Die Feinverteilung von Uran im Knochen zeigt, daß dieses Element hauptsächlich an der endostalen Oberfläche vorkommt, insbesondere an der Oberfläche des trabeculären Knochens und an den Wänden der offenen Haversschen Kanäle im kortikalen Knochen. Diese Verteilung läßt vermuten, daß Uran in einer chemischen Form vorliegt, welche sich für den Einbau in das Knochenapatit nicht eignet. Daraus folgt, daß keine signifikante diffuse Verteilung des Urans innerhalb des Knochens vorliegt.
    Notizen: Abstract A mean concentration of 2.4×10−8 g U/g ash has been obtained for normal human bone The microdistribution of uranium in bone indicates that this element is mainly restricted to endosteal surfaces; in particular the surfaces of trabecular bone and the walls of open Haversian canals in cortical bone. This distribution suggests that uranium is present in a chemical form that is not acceptable for incorporation into bone apatite and consequently there does not appear to be a significant diffuse distribution of uranium throughout bone.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 8 (1971), S. 54-72 
    ISSN: 1432-0827
    Schlagwort(e): Morphology ; Glycosaminoglycans ; Cartilage ; Chemistry ; Audioradiography ; Healing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé Une perte de substance ostéo-cartilagineuse, de taille limitée et identique, est réalisée chez le lapin adulte et la cicatrisation est étudiée histologiquement et par autoradiographie après marquagein vitro au35S-sulfate. Une analyse microchimique est pratiquée pour le contenu et la composition en glycosaminoglycanes. 1. Entre la première semaine et la 4ème et 8ème semaine, un tissu conjonctif non-métachromatique se différencie en un cartilage métachromatique et la quantité de sulfate de chondroitine augmente de façon significative aux dépens des glycoprotéines. 2. Jusqu'à la 4ème semaine, la perte de substance est surtout comblée par de l'os néoformé: après cette période, la région est comblée au delà de la limite de la surface articulaire. 3. Le cartilage hyalin, ressemblant morphologiquement, autoradiographiquement et chimiquement au cartilage articulaire, en ce qui concerne la distribution en glycosaminoglycanes, constitute la surface articulaire de la perte de substance comblée dans un tiers des cas après 8 semaines. Le cartilage hyalin s'observe surtout dans les régions où de l'os néoformé a comblé la cavité médullaire. 4. Dans les deux tiers des cas, après 8 semaines, les surfaces articulaires des zones comblées comportent, non seulement du cartilage, mais aussi du tissu fibreux se formant essentiellement sur les parties latérales et dans les régions, où la cavité médullaire, fliant face, à la surface articulaire, n'a pas été comblée par du tissue osseux. La fraction glycoprotéique augmente par rapport à la fraction chondroitine sulfate. 5. Dans la majorité des cas, après 20 semaines, le cartilage néoformé subit des phénomènes dégénératifs, qui se traduisent par une diminution en chondroitine sulfate.
    Kurzfassung: Zusammenfassung Bei ausgewachsenen Kaninchen wurde ein begrenzter, standardisierter, osteochondraler Defekt hervorgerufen, und das regenerierte Gewebe wurde histologisch und autoradiographisch durch Markierung in vitro mit35S-Sulfat und durch mikrochemische Bestimmung des Gehaltes und der Zusammensetzung der Glykosaminglykane untersucht. Die wichtigsten Befunde waren: 1. Zwischen 1 und 4–8 Wochen veränderte sich nichtmetachromatisches Bindegewebe zu metachromatisch gefärbtem Knorpel, und der Anteil an Chondroitin-Sulfat nahm auf Kosten der Glykoproteine signifikant zu. 2. Bis zu 4 Wochen war der Hauptteil des defekten Gebietes mit neugebildetem Knochen gefüllt; nach dieser Zeit lag dieser Bezirk oberhalb der Verknöcherungsgrenze in Richtung der Gelenkoberfläche. 3. Nach 8 Wochen bestand die Gelenkoberfläche des defekten Gebietes in einem Drittel der Fälle aus hyalinem Knorpel, der morphologisch, autoradiographisch und chemisch dem Gelenkknorpel in Bezug auf die Verteilung von Glykosaminoglykanen glich. Hyaliner Knorpel wurde hauptsächlich an Stellen beobachtet, wo neugebildeter Knochen die Markhöhle geschlossen hatte. 3. Nach 8 Wochen bestand die Gelenkoberfläche des defekten Gebietes in einem Drittel der Fälle aus hyalinem Knorpel, der morphologisch, autoradiographisch und chemisch dem Gelenkknorpel in Bezug auf die Verteilung von Glykosaminoglykanen glich. Hyaliner Knorpel wurde hauptsächlich an Stellen beobachtet, wo neugebildeter Knochen die Markhöhle geschlossen hatte. 4. Nach 8 Wochen bestanden Teile der Gelenkoberfläche des Defektes in zwei Dritteln der Fälle nicht nur aus Knorpel, sondern auch aus fibrösem Gewebe, welches vor allem in den seitlichen Teilen des Defektes und an Stellen vorlag, wo die Markhöhle gegenüber der Gelenkoberfläche nicht mit Knochengewebe verschlossen worden war. Die Glykoproteinfraktion nahm im Vergleich zur Chondroitin-Sulfatfraktion zu. 5. Nach 20 Wochen zeigten sich in den meisten Fällen bei neugebildetem Knorpel degenerative Veränderungen, welche durch eine gewisse Abnahme des Chondroitin-Sulfats wiedergegeben wurden.
    Notizen: Abstract A limited, standardized osteochondral defect was created in adult rabbits and the regenerated tissue was examined histologically and autoradiographically after labellingin vitro with35S-sulphate, and microchemically for its content and composition of glycosaminoglycans. The principal findings were: 1. Between 1 week and 4 to 8 weeks, non-metachromatic connective tissue differentiated to metachromatically stained cartilage, and the proportion of the chondroitin sulphate increased significantly at the expense of the glycoproteins. 2. Up to 4 weeks, the major part of the defect area was filled with newly formed bone; after this time, the area lay above the level of the “tidemark”, towards the articular surface. 3. Hyaline cartilage with morphological, autoradiographic and chemical resemblance to the articular cartilage in terms of the distribution of glycosaminoglycans constituted the articular surface of the defect area in one-third of the cases at observation times after 8 weeks. Hyaline cartilage was observed mainly in areas where newly formed bone had closed the medullary cavity. 4. In two-thirds of the cases, after 8 weeks, parts of the articular surface of the defect consisted not only of cartilage but also of fibrous tissue, occurring mainly in the lateral parts of the defect and in areas where the medullary cavity facing the articular surface had not been sealed by bone tissue. The glycoprotein fraction increased relative to the chondroitin sulphate fraction. 5. In most cases after 20 weeks, newly-formed cartilage underwent degenerative changes, which were reflected in some reduction of the chondroitin sulphate.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 8 (1971), S. 228-236 
    ISSN: 1432-0827
    Schlagwort(e): Skin ; Calcinosis ; Keratin ; Chemistry ; X-ray diffraction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé Des études histologiques antérieures ont montré que le follicle pileux est particulièrement susceptible de se calcifier, lorsque la peau de rats hypercalcémiques est lésée. Des analyses chimiques et par diffraction aux rayons X du follicule ont confirmé ce résultat. — En se basant sur l'augmentation du calcium et du phosphore, les calcifications débutent dans le tissue folliculaire 6–12 h après une blessure d'intensité moyenne de la peau de rats, ayant reçu du dihydrotachysterol (DHT), et 24–48 h après une blessure similaire chez des rats non injectés. Les diagrammes de diffraction aux rayons X sont diffus. Trois heures après la blessure, on note une augmentation du calcium du tissu folliculaire qui ne semble pas en rapport avec le DHT qui traduit probablement une liaison de calcium plutôt qu'un dépot minéral.
    Kurzfassung: Zusammenfassung Frühere histologische Untersuchungen haben gezeigt, daß der Haarfollikel besonders anfällig für Verkalkungen ist, wenn die Haut von hypercalcämischen Ratten verletzt wird. Dieses Resultat wurde nun durch direkte chemische Bestimmungen und Röntgendiffraktions-analysen von Follikelgewebe bestätigt. Aufgrund der erhöhten Calcium- und Phosphatwerte kann gesagt werden, daß nach einer leichten Quetschung der Haut von Ratten, die mit Dihydrotachysterol (DHT) behandelt wurden, im Haarfollikelgewebe nach 6–12 Std Mineral-ablagerungen stattfanden, wogegen Kontrollratten mit der gleichen leichten Hautverletzung diese Ablagerungen erst nach 24–48 Std zeigten. Röntgendiffraktionsanalysen ergaben ein diffuses Apatit-Muster. Innerhalb 3 Std nach der Verletzung wurde ein Anstieg des Calcium-gehaltes im Follikelgewebe beobachtet, der nicht im Zusammenhang mit der DHT-Behandlung stand, also nicht eine Mineralablagerung, sondern eher eine Bindung von Calcium widerspiegelte.
    Notizen: Abstract Previous histological investigations have shown that the hair follicle is particularly susceptible to mineralization when the skin of hypercalcaemic rats is injured. Direct chemical and X-ray diffraction analyses of follicle tissue have now confirmed this finding. As judged by increases in both calcium and phosphorus, mineral deposits began to form in hair follicle tissue 6–12 h after a mild crush injury to the skin of rats dosed with dihydrotachysterol (DHT), and 24–48 h after a similar injury to the skin of non-dosed rats. X-ray diffraction gave a diffuse apatite pattern. Within 3 h of injury there was a rise in the calcium content of follicle tissue which was not related to DHT-dosing and which was probably a reflection of calcium binding rather than mineral deposition.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 8 (1971), S. 304-319 
    ISSN: 1432-0827
    Schlagwort(e): Chemistry ; Calcium ; Phosphate ; Solubility ; Computer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé Un programme d'ordinateur a été mis au point pour calculer les activités ioniques du calcium et l'orthophosphate dans un grand nombre de solutions. Dans le cas de solutions synthétiques, les calculs sont vérifiés en comparant les valeurs de pH, obtenues par ordinateur, avec celles observées expérimentalement. Des essais de ce type, avec des solutions possèdant des concentrations de calcium et d'orthophosphate trouvées dans les liquides biologiques et à des valeurs de pH variant de 3.00 à 10.00, indiquent que le programme est adapté pour des applications biologiques. Le programme n'est pas effectif pour des solutions, dans les lesquelles l'ion bromure est la source principale de la force ionique, sans doute, par manque d'équation étendue de Debye-Hückel dans ces circonstances. Aucune formation de complexe de phosphate de sodium n'a été notée à des concentrations biologiques normales.
    Kurzfassung: Zusammenfassung Es wurde ein Computer-Programm ausgearbeitet, um die Ionenaktivitäten von Calcium und Orthophosphat in einer breiten Varietät von Lösungen zu berechnen. Die Berechnungen wurden bei synthetischen Lösungen durch Vergleiche zwischen den auf diese Weise errechneten pH-Werten und den experimentell gefundenen kontrolliert. Diese Art Kontrollen mit Calcium-und Orthophosphatkonzentrationen, wie sie in biologischen Flüssigkeiten gefunden werden, und mit pH-Werten zwischen 3,0 und 10,0 wies darauf hin, daß das Programm für biologische Anwendungen geeignet war. Das Programm konnte nicht benützt werden für solche Lösungen, bei welchen hauptsächlich das Bromidion zur Einstellung der Ionenstärke verwendet wurde, vermutlich weil die erweiterte Debye-Hückel-Gleichung unter diesen Umständen nicht anwendbar ist. Die Bildung eines Natriumphosphat-Komplexes unter normalen biologischen Konzentrationen konnte nicht nachgewiesen werden.
    Notizen: Abstract A computer program has been designed to calculate the ionic activities of calcium and orthophosphate in a wide variety of solutions. In the case of synthetic solutions the calculations were checked by comparing the computed pH values with those observed experimentally. Tests of this type with solutions having the concentrations of calcium and orthophosphate found in biological fluids and with pH values ranging from pH 3.0–10.0 indicated that the program was suitable for biological applications. The program was not effective for solutions in which the bromide ion was a principal source of ionic strength probably because of the failure of the extended Debye-Hückel equation under those circumstances. No evidence for the formation of any sodium phosphate complex at normal biological concentrations could be found.
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 10 (1972), S. 171-197 
    ISSN: 1432-0827
    Schlagwort(e): Amorphous ; Crystalline ; Calcium phosphate ; Chemistry ; Composition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé Des échantillons non lavés de phosphate de calcium amorphe (ACP) contiennent une fraction labile, non remplaçable, riche en phosphate acide avec un rapport Ca/P faible: cette fraction est perdue de façon irréversible au cours du lavage. De l'ACP frais, précipité entre pH 6.6–10.6, varie dans un rapport molaire Ca/P de 1.18 à 1.50 et dans un rapport HPO 4 2− /P total de 33.0% à 10.1%. A pH 7.40, de l'ACP frais a un rapport molaire Ca/P de 1.36±0.02 et contient 22.8 (±2.2)% HPO 4 2− . Les résultats obtenus avec du précipité non lavé ne peuvent s'expliquer par du Ca2+ emprisonné et de l'HPO 4 2− ou du Na+, Cl− et CO 3 2− exogènes. Les phosphates de calcium amorphes constituent une classe de sels ayant des caractères chimiques variables et des propriétés physiques identiques, comparables au verre. Le CaHPO4·xH2O non cristallin peut être un ACP, surtout au cours des phases précoces de formation. A des pH physiologiques, l'ACP se transforme en petits cristaux applatis contenant de fortes quantités de phosphate acide facilement remplaçable. Le fait de laver la couche de surface produit un changement chimique dans les nouveaux cristaux: des cristaux non lavés donnent des diagrammes de diffraction d'apatite peu cristallins, ainsi que des spectres infra-rouges peu nets, intermédiaires entre des apatites et du phosphate octocalcique. Des explications structurales sont proposées et les compositions minérales amorphe/cristalline de l'os et du cartilage sont recalculées.
    Kurzfassung: Zusammenfassung Ungewaschene Proben von amorphem Calciumphosphat (ACP) enthalten eine unersetzliche labile Fraktion, welche reich an saurem Phosphat ist und ein niederes Ca/P-Verhältnis hat und welche während des Waschprozesses unwiderruflich verloren geht. Natives ACP, welches im pH-Bereich 6,6–10,6 ausgefällt wurde, variierte im molaren Ca/P-Verhältnis zwischen 1,18 und 1,50 und in HPO 4 2− /totales P zwischen 33,0 und 10,1%. Bei pH 7,40 hatte natives ACP ein molares Ca/P-Verhältnis von 1,36±0,02 und enthielt 22,8 (±2,2)% HPO 4 2− . Die Werte beim ungewaschenen Niederschlag rühren weder von aus dem Überstand aufgenommenem Ca2+ und HPO2−, noch von außen kommendem Na+, Cl− und CO 3 2− her. Die amorphen Calciumphosphate werden als eine Klasse von Salzen erkannt, welche veränderliche chemische, aber identische glasartige physicochemische Eigenschaften haben. Nicht kristallines CaHPO4·xH2O kann auch ein ACP sein, besonders in den frühen Bildungsstadien. Bei physiologischem pH verwandelt sich ACP in kleine plattenförmige Kristalle, welche große Mengen von leicht ersetzbarem saurem Phosphat enthalten. Das Waschen dieser Oberflächenschicht erzeugte chemische Veränderungen in den resultierenden Kristallen; ungewaschene Kristalle zeigten ein Diffraktionsmuster, das nur schwach demjenigen des kristallinen Aspatites glich, aber ein schlecht aufgelöstes Infrarotspektrum, welches zwischen Apatit und Octocalciumphosphat war. Es werden strukturelle Erklärungen für alle diese Phenomena diskutiert, und revidierte amorph/kristalline Mineralzusammensetzungen von Knochen und Knorpel wurden neu berechnet.
    Notizen: Abstract Unwashed samples of amorphous calcium phosphate (ACP) contain an irreplaceable labile fraction, rich in acid phosphate and low in Ca/P ratio, which is irreversibly lost during the washing process. Native ACP precipitated in the pH range 6.6–10.6 varied in Ca/P molar ratio from 1.18 to 1.50 and in HPO 4 2− /total P from 33.0% to 10.1%. At pH 7.40, native ACP had a Ca/P molar ratio of 1.36±0.02 and contained 22.8 (±2.2)% HPO 4 2− . Unwashed precipitate data could not be attributed to either trapped supernatant Ca2+ and HPO 4 2− or extraneous Na+, Cl−, and CO 3 2− . The amorphous calcium phosphates are recognized as a class of salts having variable chemical but identical glass-like, physicochemical properties. Non-crystalline CaHPO4·xH2O may also be an ACP, especially during early formative stages. At physiological pH, ACP transforms to small platy crystals containing large amounts of readily-replaceable acid phosphate. Washing this surface layer produced chemical alterations in the resultant crystals; unwashed crystals had poorly-crystalline apatitic diffraction patterns but exhibited poorly-resolved infrared spectra intermediate between apatite and octacalcium phosphate. Structural explanations for all these phenomena are discussed, and revised bone and cartilage amorphous/crystalline mineral compositions have been re-calculated.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 23 (1977), S. 39-44 
    ISSN: 1432-0827
    Schlagwort(e): Dental cementum ; Collagen ; Protein ; Chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary Cyanogen bromide (CNBr) peptides were prepared of the insoluble collagen of bovine dental cementum. Following chromatographic separation, the peptides were identified by their amino-acid composition. Type I collagen ([α1(I)]2α2) accounted for more than 90% of the organic matrix, while Type III collagen ([α1(III)]3) was present at a level of approximately 5%. Amino-acid analyses revealed that the CNBr peptides from α1(I) and α2 chains of cementum closely resembled the corresponding peptides from calf skin. The only systematic difference was a higher level of hydroxylation of prolyl and lysyl residues of the cementum peptides.
    Materialart: Digitale Medien
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 23 (1977), S. 87-94 
    ISSN: 1432-0827
    Schlagwort(e): Calcium ; Osteoporosis ; Lactation ; Chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The calcium homeostatic mechanism was challenged in adult female rats by feeding them a calcium-deficient diet containing oxalate, and by subjecting them to pregnancy and lactation. The regimen caused a substantial weight loss, especially in those animals which reared their young well. Severe hypocalcaemia was observed in the lactating rats. Serum-P was slightly elevated. The content of hydroxyproline in serum was considerably elevated, reflecting the degree of calcium deprivation. Serum proteins were least influenced. The calcium depriving regimen reduced the growth of long bones, but did not stop it. The ash content of the bones was considerably reduced, the degree of reduction depended on the degree of calcium deprivation. Ash as percentage of total bone organ was reduced, but not to the same extent as total ash. Analyses of different parts of femur showed that the proximal and distal parts had lost more bone mineral than the diaphyseal shaft. The ash content of cortical bone tissue from the femur was estimated by a volumetric method. No differences were observed between test groups and controls, indicating that no measurable amounts of bone mineral had been removed from the walls of the vascular canals or by osteocytic osteolysis. Planimetric determinations on cross sections from femora disclosed that a great amount of bone had been removed from the endosteal surface of the diaphysis, while the periosteal surface demonstrated reduced bone apposition.
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 8 (1971), S. 197-210 
    ISSN: 1432-0827
    Schlagwort(e): Fluorescence ; Calcium ; Collagen ; Chemistry ; Bone ; Dentine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé Des composants fluorescents de l'os et la dentine sont séparés des hydrolysats alcalins de leur marice sur des colonnes Sephadex C25 CM d'échange cationique. Les concentrations en fluorescence et le spectre d'excitation (λ max 330 nm) et d'émission (λ max 395 nm) sont les mêmes que ceux observés au niveau des matrices intactes et gélatinisées. Les paramètres de fluorescence ne sont pas altérés par hydrolyse. La filtration sur gel à l'aide de colonnes Sephadex G 10 perment de différencier le matériel isolé en deux composants, ayant la même fluorescence et la même absorption UV. La fluorescence est indépendante de pH de 3.5–9.5. Des études de dialyse et de filtration sur gel de matrices gélatinisées indiquent une association étroite du matériel fluorescent avec les chaines polypeptidiques de collagène.
    Kurzfassung: Zusammenfassung Fluorescierende Bestandteile aus Knochen und Dentin wurden in Sephadex C25 CM Kationen-Austauschersäulen von alkalischen Hydrolysaten ihrer Matrices getrennt. Die Fluorescenzintensitäten sowie die Erregungs- (λ max 330 nm) und Emissions- (λ max 395 nm) Spektren waren dieselben wie bei intakten und gelatinisierten Matrices. Die Fluorescenzparameter wurden durch die Hydrolyse nicht verändert. Eine Gelfiltration über Sephadex-G10-Säulen trennte das isolierte Material in 2 Komponenten auf, welche gleiche Fluorescenz- und UV-Absorptionseigenschaften zeigten. Im pH-Bereich zwischen 3,5 und 9,5 war die Fluorescenz unabhängig vom pH. Dialysierversuche sowie Gelfiltrationsexperimente mitden gelatinisierten Matrices zeigten eine starkgefügte Bindung des fluorescierenden Materials mit den Polypeptidketten des Kollagens.
    Notizen: Abstract Fluorescent components in bone and dentine were separated from alkaline hydrolysates of their matrices on Sephadex C25 CM cationic exchange columns. The fluorescence levels, and the excitation (λ max 330 nm) and emission (λ max 395 nm) spectra, were the same as those observed in the intact and gelatinised matrices. The fluorescence parameters were unaltered by the hydrolysis procedure. Gel filtration on Sephadex G. 10 columns further resolved the isolated material into two components with the same fluorescence and UV absorption properties. The fluorescence was independent of pH over the range 3.5–9.5. Dialysis and gel filtration studies on the gelatinised matrices indicated a firmly-bonded association of the fluorescent material with the collagen polypeptide chains.
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 12 (1973), S. 125-136 
    ISSN: 1432-0827
    Schlagwort(e): Mineralization ; Molt ; Isopod ; Chemistry ; Light microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé Au cours de la phase inhabituelle de mue d'un isopode d'eau courante,Lirceuts brachyrus, la moitié postérieure de l'exosquelette est éliminée 24 heures avant la moitié antérieure. A ce stade, une reminéralisation se développe dans la partie postérieure alors que la partie antérieure est dans un stade de pré-mue. Le pourcentage de différence en calcium dans les deux moitiés à mi-mue et mue complète est respectivement de 22% (p〈0.01) et 33% (p〈0.01), indiquant une complexation du calcium pendant la mue. La rapidité de la reminéralisation est illustrée par le fait que le contenu minéral total double dans la partie postérieure entre la mi-mue et la mue totale et dans la partie antérieure entre la fin de la mue et un jour après. Le carbonate de calcium, sous forme de calcite, a pu être identifié par diffraction électronique de coupes fines des téguments.
    Kurzfassung: Zusammenfassung Während der ungewöhnlichen Häutungssequenz des Frischwasser-IsopodenLirceus brachyurus (Harger) wird die hintere Hälfte des äußeren Skeletts 24 Std vor der vorderen Hälfte abgestoßen. In der halbgehäuteten Phase erfolgt Remineralisation im hinteren Teil, während der vordere Teil in einem Vorhäutungszustand ist. Der prozentuale Unterschied des Calciums in den zwei Hälften bei Halb- und Vollhäutungszustand ist 22% (p〈0,01) bzw. 33% (p〈0,01), was andeutet, daß Calcium während der Häutung abgesondert wird. Die Geschwindigkeit der Remineralisation erhellt aus der Tatsache, daß sich der Gesamtmineralgehalt im hinteren Teil zwischen Halt- und Vollhäutung, in der vorderen Hälfte jedoch zwischen Endhäutung und einem Tag nach der Häutung verdoppelt. Calciumcarbonat in kristalliner Calcitform wurde mittels Elektronendiffraktion von dünnen Hautschnitten nachgewiesen.
    Notizen: Abstract During the unusual molt sequence of the fresh-water isopod,Lirceus brachyrus (Harger), the posterior half of the exoskeleton is shed 24 hours before the anterior half. At the half-molt stage, occurs in the posterior part while the anterior portion is in a pre-molt condition. The percentage difference in calcium in the two halves at half-molt and full-molt is22 (p〈0.01) and33 (p〈0.01) respectively, an indication that calcium is sequestered during The rapidity of remineralization is illustrated by the fact that the total mineral content doubles in the posterior part between half and full molt and in the anterior half between the end of molt and one day after ecdysis. Calcium carbonate in the calcite cystalline form was demonstrated by electron diffraction of thin sections of the integument.
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 13 (1973), S. 259-270 
    ISSN: 1432-0827
    Schlagwort(e): Fluorapatite ; Exchange ; Chemistry ; Crystallography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé Un échantillon minéral provenant de Burgess, Canada s'est révélé être un speciment exceptionnellement pur de fluoroapatite après analyse chimique et cristallographique. La composition globale de cet échantillon est la suivante: $$(Ca^2 )9.98(Sr^{2 + } ,Na^ + ,K^ + ,Mg^{2 + } )0.02(PO_4^{3 - } )5.98(HCO_3^ - ,CO_3^{2 - } )0.02(F^ - )2$$ . L'axe cristallographique C est de 6.865 A et l'axe a de 9.374 A. Des expériences d'échanges réalisés à l'aide de45Ca,32P et18F indiquent la présence de gros cristallites de surface spécifique de l'ordre de 1 m2/g. Il apparait que l'interprétation physique des processus d'échange ne nécessite pas l'existence de compartiments séparés, avec chacun son propre facteur cinétique, les échanges semblent être simplement liés à un changement exponentiel dans l'énergie libre de la réaction. Pour la réaction suivante: $$(Ca)_5 (PO_4 )_3 OH solide + (F^ - ) \rightleftarrows (Ca)_5 (PO_4 )_3 F solide + (OH^ - )$$ , la constante thermodynamique de 101.26 a été calculée, suggérant que le fluorapatite se forme toujours aux dépens de l'hydroxyapatite dans des conditions physiologiques. Cette transformation se continue en abaissant le pH.
    Kurzfassung: Zusammenfassung Eine Mineralprobe aus Burgess, Kanada, erwies sich nach chemischer und kristallographischer Analyse als außergewöhnlich reines Fluorapatit. Die Gesamtzusammensetzung entspricht: $$(Ca^{2 + } )_{9,98} (Sr^{2 + } ,Na^ + ,K^ + ,Mg^{2 + } )_{0,02} (PO_4^{3 - } )_{5,98} (HCO_3^ - ,CO_3^{2 - } )_{0,02} (F^ - )_2 $$ . Die kristallographische c-Achse wurde bestimmt und ergab 6,865 Å, und die a-Achse ergab 9,374 Å. Austauschwerte, welche durch Anwendung von45Ca,32P und18F erhalten wurden, deuteten auf große Kristalliten mit einer spezifischen Oberfläche von ca. 1 m2/g. Die Befunde deuten darauf hin, daß für die physikalische Erklärung des Austauschvorganges keine separaten Kompartimente mit eigenen kinetischen Faktoren nötig sind, sondern daß der Austausch mit dem exponentiellen Wechsel in der freien Energie der Reaktion in einfacher Beziehung steht. Für die Reaktion $$(Ca)_5 (PO_4 )_3 OH_{in fester Form} + (F^ - ) \rightleftarrows (Ca)_5 (PO_4 )_3 F_{in fester Form} + (OH^ - )$$ wurde als thermodynamische Konstante 101,26 errechnet, was darauf deutet, daß unter physiologischen Bedingungen immer Fluorapatit auf Kosten von Hydroxyapatit entsteht. Diese Umwandlung wird erhöht, wenn das pH erniedrigt wird.
    Notizen: Abstract A mineral specimen from Burgess, Canada, proved upon chemical and crystallographic analyses to be an exceptionally pure sample of fluorapatite. The over-all composition corresponds to $$(Ca^{2 + } )_{9.98} (Sr^{2 + } ,Na^ + ,K^ + ,Mg^{2 + } )_{0.02} (PO_4^{3 - } )_{5.98} (HCO_3^ - ,CO_3^{2 - } )_{0.02} (F^ - )_2 $$ . The crystallographic c-axis was determined to be 6.865 Å, and the a-axis 9.374 A. Exchange data obtained by employing45Ca,32P, and18F indicate the presence of large crystallites with a specific surface of the order of 1 m2/g. It is indicated that the physical interpretation of the exchange process does not require the existence of separate departments, each with its own kinetic factor, but that the exchange may be simply related to the exponential change in the free energy of the reaction. For the reaction $$(Ca)_5 (PO_4 )_3 OH_{solid} + (F^ - ) \rightleftarrows (Ca)_5 (PO_4 )_3 F_{solid} + (OH^ - )$$ the thermodynamic constant has been calculated to be 101.26, implying that fluorapatite always will form at the expense of hydroxyapatite under physiologic conditions. This transformation will be furthered by lowering the pH.
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  • 20
    ISSN: 1432-0827
    Schlagwort(e): Bacterial amphophile ; Purification ; Chemistry ; Resorption ; Ca influx ; Cyclic AMP
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The bone resorptive factor and amphipathic antigen (AcA) previously identified by us in preparations fromActinomyces viscosus have been partially purified, characterized chemically, and compared. They elute at the same location on chromatography with Ac 22. The fatty acid composition of AcA and the bone resorptive factor is the same. Some differences in carbohydrate composition are observed. TheActinomyces factor does not affect calcium influx or cyclic AMP in isolated bone cells. Therefore it is concluded that AcA stimulates resorption either by gaining entrance into bone cells or by way of a yet undetermined second messenger.
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Astrophysics and space science 224 (1995), S. 81-84 
    ISSN: 1572-946X
    Schlagwort(e): Chemistry ; Depletions ; Shocks ; IRAS 05338-0624 ; NGC 1333 IRAS 4
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract High resolution interferometer and single-dish observations of young, deeply embedded stellar systems reveal a complex chemistry in the circumstellar environments of low to intermediate mass stars. Depletions of gas-phase molecules, grain mantle evaporation, and shock interactions actively drive chemical processes in different regions around young stars. We present results for two systems, IRAS 05338-0624 and NGC 1333 IRAS 4, to illustrate the behavior found and to examine the physical processes at work.
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Astrophysics and space science 216 (1994), S. 153-154 
    ISSN: 1572-946X
    Schlagwort(e): Chemistry ; Molecular Hydrogen ; Cloud Models
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Observations of the CO J=1-0 line are commonly used as a tracer for molecular material in clouds. The ratio of the H2 column density to the integrated intensity of this line,X, is often taken to be constant, despite theoretical and observational uncertainty. We have tried to identify how this ratio depends on cloud parameters, testing a simple theoretical argument suggesting its invariance with respect to density. The apparent constancy can be understood if clouds are clumpy on scales of Av ≈ 1-2 mag.
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Boundary layer meteorology 85 (1997), S. 197-222 
    ISSN: 1573-1472
    Schlagwort(e): Turbulence ; Chemistry ; Closure ; Convective boundary layer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract We study the interactions of chemistry and turbulent mixing of tracersin the convective boundary layer with a second-order closure model,including higher order chemistry terms. In order to limit the number of predictive equations we prescribe the profiles for ¯w¯Θ, ¯w¯θ ¯θ and the lengthscale l. However, for model validation we treat temperature and humidity asinert tracers, and compare the results with profiles observed during theAir Mass Transformation Experiment, and with similarity expressions for thesurface layer. We find good agreement of the mean profiles, but the (co-)variances are slightly underpredicted. Furthermore, the model usesdiagnostic equations expressing third moments of concentration in terms ofsecond moments and their vertical derivatives. They are compared withlarge-eddy model results, showing good agreement and, therefore, thesimplifications are justified. The model is applied to the transport of two gases subject to one bimolecular reaction. The importance of concentration correlations on themean transformation rate is studied. For two gases diffusing in oppositedirections we find for moderate and fast chemistry a 50% and90% decreased transformation rate due to the negatively correlatedconcentrations. These values are similar to large-eddy results of Schumannand Sykes et al. For two bottom-up tracers we find that the covariance ofboth reactive species is either positive or negative, increasing or reducingthe effective transformation rate depending on the Damköhler number (the ratio of the turbulent and the chemistry timescale). A significantdirect influence of chemistry on the flux divergence is found in bothcases. According to the model the effective transport to mid-levels of theboundary layer is increased when two reactive tracers diffuse in oppositedirections, and decreased in the case of two bottom-up tracers.
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  • 24
    ISSN: 1432-0878
    Schlagwort(e): Milk ; Fat globule membrane ; Carbohydrates ; Chemistry ; Ruthenium red ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The fat globules of the cream fractions of human and rat milk were stained with ruthenium red. Under the electron microscope, discrete granules and an amorphous coat of lesser density are seen at the surface of the milk fat globules. Since ruthenium red binds anionic groups selectively, it is probable that the granules containe the greatest concentration of these groups. The cream fraction of rat milk contains hexoses, hexosamines, methylpentoses and sialic acid. Methylpentoses and hexosamines are significantly enriched in the cream fraction. It is concluded that the finding of a surface coat in milk fat globules is in keeping with the Bargmann-Knoop model and suggests a distinct mechanism for carrying certain complex carbohydrates in milk. The role of the negative charges at the outer surface of the membrane coat in maintaining fat globules in suspension and in binding certain cations such as calcium is suggested.
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  • 25
    ISSN: 1573-739X
    Schlagwort(e): Antimalarials ; Artemisia annua L ; Artemisinin ; Biosynthesis ; Chemistry ; Clinical trials ; Pharmacology ; Phytochemistry ; Sesquiterpenes ; Toxicology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Artemisinin, a sesquiterpene lactone endoperoxide isolated fromArtemisia annua L., and a number of its semisynthetic derivatives have shown to possess antimalarial properties. They are all eflective againstPlasmodium parasites that are resistant to the newest and commonly used antimalarial drugs. This article gives a survey of the literature dealing with artemisinin-relaled antimalarial issues that have appeared from the end of 1989 up to the beginning of 1994. A broad range of medical and pharmaceutical disciplines is covered, including phytochemical aspects like the selection of high-producing plants, analytical procedures, and plant biotechnology. Furthermore, the organic synthesis of artemisinin derivatives is discussed, as well as their mechanism of action and antimalarial activity, metabolism and pharmacokinetics, clinical studies, sideeffects and toxicology, and biological activities other than antimalarial activity.
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Pharmacy world & science 10 (1988), S. 93-95 
    ISSN: 1573-739X
    Schlagwort(e): Anthracyclines ; Chemistry ; Drug stability ; Mitomycins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Pharmacy world & science 10 (1988), S. 101-116 
    ISSN: 1573-739X
    Schlagwort(e): Chemistry ; Chromatography ; Etoposide ; Immunoassay ; Metabolism ; Podophyllotoxin ; Pharmacokinetics ; Teniposide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Etoposide (VP 16-213) and teniposide (VM 26) are semisynthetic epipodophyllotoxin derivatives active against a variety of tumours. The clinical efficacy has led to an increasing interest in these compounds. This review presents information on the mechanism of action, biochemical pharmacology, bioanalysis, metabolism and pharmacokinetics of etoposide and teniposide.
    Materialart: Digitale Medien
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Pharmacy world & science 13 (1991), S. 109-118 
    ISSN: 1573-739X
    Schlagwort(e): Chemistry ; Consumer product safety ; Drug packaging ; Environmental pollution ; Plasticizers ; Polyvinyls
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract In this report the state of the art with respect to PVC as pharmaceutical packaging material is described. A general introduction into the applications of PVC is followed by a description of its production process. The metabolic effects of the monomer of PVC, vinyl chloride and of the most commonly used plasticizer diethylhexylphthalate are mentioned. Special attention is given to the pharmaceutical properties of plasticized PVC bags in comparison to other plastics and the environmental aspects of waste PVC disposal. Although there are emotional and political queries regarding the future use of PVC as a (pharmaceutical) packaging material, we conclude that there is no scientific justification for a total or partial ban of PVC. PVC will remain a fact of life as a cheap, versatile, high-performance and well-investigated plastic material for medical and pharmaceutical applications, to be replaced by newer plastics only for certain well-defined indications where the requirements of the plastic to be used are so specific that it will economically and technically be justified to use another polymer. Community and hospital pharmacists have to be prepared for a role in intake of waste plastic disposables, probably against deposit money, in order to fulfil the logistics needed for recycling.
    Materialart: Digitale Medien
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Journal of science education and technology 5 (1996), S. 193-201 
    ISSN: 1573-1839
    Schlagwort(e): Chemistry ; chemistry education ; multiple intelligences ; imagery ; visual-spatial thinking
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Allgemeine Naturwissenschaft , Technik allgemein
    Notizen: Abstract Chemistry has evolved from a science dominated by mathematics into a science highly dependent on spatial-visual intelligence. Yet the chemical content of introductory courses remains taught essentially the same as 40–50 years ago. Chemistry, today, is recognized by chemists as the molecular science. Yet, school chemistry is alienated from that perception. Thanks to the computer, young people are more comfortable with visual imaging than their instructors were at the same age. Thus the time is rife to reinvigorate chemistry education by means of the visual-spatial approach, an approach wholly in conformance with the way modern chemistry is thought about and practiced.
    Materialart: Digitale Medien
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  • 30
    Digitale Medien
    Digitale Medien
    Springer
    Pharmacy world & science 8 (1986), S. 245-251 
    ISSN: 1573-739X
    Schlagwort(e): Analysis ; Antineoplastic agents ; Biosynthesis ; Botany ; Chemistry ; Cytotoxins ; Eupatorium cannabium ; Sesquiterpenes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract A review onEupatorium cannabinum L. is given, including botany, history and constituents. The sesquiterpene lactones are discussed in more detail, covering their biosynthesis, isolation, analysis and biological activity. Special attention is paid to the cytotoxic and antitumour activities of the sesquiterpene lactones.
    Materialart: Digitale Medien
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  • 31
    Digitale Medien
    Digitale Medien
    Springer
    Pharmacy world & science 9 (1987), S. 305-314 
    ISSN: 1573-739X
    Schlagwort(e): Atrial natriuretic factor ; Blood pressure ; Chemistry ; Diuresis ; Homeostasis ; Kidney ; Muscle, smooth ; Natriuresis ; Receptors, endogenous compounds ; Renin-angiotensin system
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract It is now known that cardiac atria play an important role in blood pressure and volume regulation. Mechanical distension of the atria results in the release of a potent diuretic and natriuretic agent or agents termed the atrial natriuretic factor (ANF). Several structurally related forms of ANF exist in man and it is thought that these represent precursory forms of a single optimally active molecule and/or the presence of more than one form of active ANF. The chemical structure of ANF between different mammalian species is similar. ANF receptors have been identified in kidney, brain, vascular endothelial and smooth muscle cells, tracheal and bronchial smooth muscle and the adrenal glands of many mammalian species, including man. This would suggest that ANF influences blood pressure and volume homoeostasis by affecting any one of a number of biochemical or physiological mechanisms via different target tissues. ANF is now considered a potentially valuable therapeutic agent for the treatment of hypertension and congestive heart failure. Synthesis of potent receptor antagonists could be extremely useful in the treatment of various clinical situations which are produced or complicated by endogenously produced ANF, such as chronic orthostatic hypotension.
    Materialart: Digitale Medien
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  • 32
    Digitale Medien
    Digitale Medien
    Springer
    Plant systematics and evolution 171 (1990), S. 1-14 
    ISSN: 1615-6110
    Schlagwort(e): Angiosperms ; Compositae ; Chemistry ; systematics ; evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The broad knowledge of the chemistry of theCompositae allows the discussion of its relevance for the systematics and evolution within the family. Furthermore a separation into subfamilies can be supported by the observed differences in the distribution of the main constituents in the tribes.
    Materialart: Digitale Medien
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  • 33
    Digitale Medien
    Digitale Medien
    Springer
    Earth, moon and planets 88 (2000), S. 35-58 
    ISSN: 1573-0794
    Schlagwort(e): Chemistry ; interplanetary dust particles (IDPs) ; Leonids ; meteor trails ; meteoroids ; meteors ; structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The cometary Leonid meteoroids represent a size range in between largest carbon-richIDPs and the smallest CI meteorites. Their dustball structure and chemistry offer anopportunity to constrain hierarchical dust accretion inferred from petrologic studies ofaggregate and cluster IDPs. The Leonid shower meteoroids of known ``comet ejection''ages provide an opportunity to study space weathering of cometary dust over periodsof up to several hundred years. The meteors and aggregate and cluster IDPs displaycontinuous thermal modification of organics and volatile element (Na, K-bearing phases), that occur as discrete minerals and amorphous solids each different response during kinetically controlled ablation. Leonid meteoroids are not excessively Na-rich. The occurrences of Leonid meteors can now be accurate predicted and combined withknowledge better models for the settling rates, collections of surviving dust becomea comet nucleus-sampling mission.
    Materialart: Digitale Medien
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  • 34
    Digitale Medien
    Digitale Medien
    Springer
    Astrophysics and space science 233 (1995), S. 125-137 
    ISSN: 1572-946X
    Schlagwort(e): Interstellar Medium ; Dark Clouds ; Chemistry ; Bistability ; C-shock Waves
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Shock waves perturb the chemical state of the interstellar gas. We consider the effects of C-shocks on the composition of molecular clouds, for a range of values of the pre-shock gas density and magnetic induction. The time required to re-establish equilibrium in the post-shock gas depends on the initial conditions and can become very large. The significance of the two known chemical phases of dark clouds and of bistability is considered in this context.
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  • 35
    Digitale Medien
    Digitale Medien
    Springer
    Astrophysics and space science 233 (1995), S. 161-164 
    ISSN: 1572-946X
    Schlagwort(e): Stars ; Chemistry ; Diffusion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We have assessed the role of diffusion in determining chemical abundances in molecular interface regions. Chemical models have been developed which include the appropriate diffusion terms and that are appropriate to a narrow diffusion region (∼0.01pc) that may exist at the interface between a dark core and a hot, shocked T-Tauri wind. We have assumed pressure balance throughout and have calculated the chemical abundances as functions of time and position through the interface. The results show that significant enhancements of detectable molecules/transitions are expected (e.g. CO J=6→5, OH and CH). Using a realistic value of the diffusion coefficient a diffusive region of dimension 0.01pc may be established within about 104 years. In general it seems likely that diffusion processes are highly significant on these and smaller lengthscales.
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  • 36
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publikationsdatum: 2016-07-08
    Beschreibung: Separation and purification are critical industrial processes for separating components of chemical mixtures, and these processes account for about half of industrial energy usage (1). Gas mixtures of compounds with very similar physical properties are particularly difficult to separate. On pages 137 and 141 of this issue, Cadiau et al. (2) and Cui et al. (3), respectively, show that microporous materials can be designed to have high adsorption capacity and selectivity for particular hydrocarbons, enabling energy-efficient separation. Author: Jerry Y. S. Lin
    Schlagwort(e): Chemistry
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Geologie und Paläontologie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 37
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publikationsdatum: 2016-05-27
    Beschreibung: Biomass-degrading microorganisms use lytic polysaccharide monooxygenase (LPMO) enzymes to help digest cellulose, chitin, and starch. By cleaving otherwise inaccessible crystalline cellulose chains, these enzymes provide access to hydrolytic enzymes. LPMOs are of interest to biotechnology because efficient depolymerization of cellulose is a major bottleneck for the production of biologically based chemicals and fuels. On page 1098 of this issue, Kracher et al. (1) compare LPMO-reducing substrates in fungi from different taxonomic groups and lifestyles, based on both biochemical and genomic evidence. The results provide insights into reductive activation of LPMO that are important for developing more efficient industrial enzymes for lignocellulose biorefineries. Author: Angel T. Martínez
    Schlagwort(e): Chemistry
    Print ISSN: 0036-8075
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    Thema: Biologie , Chemie und Pharmazie , Geologie und Paläontologie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 38
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publikationsdatum: 2016-03-25
    Beschreibung: Author: Marc S. Lavine
    Schlagwort(e): Chemistry
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Geologie und Paläontologie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 39
    Publikationsdatum: 2002-11-02
    Beschreibung: The interaction of climate and the timing of low tides along the West Coast of the United States creates a complex mosaic of thermal environments, in which northern sites can be more thermally stressful than southern sites. Thus, climate change may not lead to a poleward shift in the distribution of intertidal organisms, as has been proposed, but instead will likely cause localized extinctions at a series of "hot spots." Patterns of exposure to extreme climatic conditions are temporally variable, and tidal predictions suggest that in the next 3 to 5 years "hot spots" are likely to appear at several northern sites.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Helmuth, Brian -- Harley, Christopher D G -- Halpin, Patricia M -- O'Donnell, Michael -- Hofmann, Gretchen E -- Blanchette, Carol A -- New York, N.Y. -- Science. 2002 Nov 1;298(5595):1015-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉University of South Carolina, Department of Biological Sciences and Marine Sciences Program, Columbia, SC 29208, USA. helmuth@biol.sc.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12411702" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Bivalvia/*physiology ; *Body Temperature ; *Climate ; *Ecosystem ; Environment ; Geography ; Pacific Ocean ; Pacific States ; Seasons ; *Seawater ; Temperature ; *Water Movements
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 40
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2002-06-18
    Beschreibung: Hundreds of coral species coexist sympatrically on reefs, reproducing in mass-spawning events where hybridization appears common. In the Caribbean, DNA sequence data from all three sympatric Acropora corals show that mass spawning does not erode species barriers. Species A. cervicornis and A. palmata are distinct at two nuclear loci or share ancestral alleles. Morphotypes historically given the name Acropora prolifera are entirely F(1) hybrids of these two species, showing morphologies that depend on which species provides the egg for hybridization. Although selection limits the evolutionary potential of hybrids, F(1) individuals can reproduce asexually and form long-lived, potentially immortal hybrids with unique morphologies.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Vollmer, Steven V -- Palumbi, Stephen R -- New York, N.Y. -- Science. 2002 Jun 14;296(5575):2023-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA. svollmer@oeb.harvard.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12065836" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Bayes Theorem ; *Biological Evolution ; Calmodulin/genetics ; Caribbean Region ; Cnidaria/anatomy & histology/*classification/*genetics/physiology ; Collagen/genetics ; DNA, Mitochondrial/genetics ; *Ecosystem ; Environment ; *Genetic Variation ; Haplotypes ; *Hybridization, Genetic ; Introns ; Likelihood Functions ; Polymorphism, Genetic ; Reproduction ; Reproduction, Asexual ; Sequence Analysis, DNA ; Species Specificity
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 41
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2003-05-31
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Demaine, Linda J -- Fellmeth, Aaron X -- New York, N.Y. -- Science. 2003 May 30;300(5624):1375-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉RAND, Santa Monica, CA 90401, USA. demaine@rand.org〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12775825" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Aluminum Oxide ; Chemical Phenomena ; Chemistry ; Natural Science Disciplines ; Patents as Topic/*legislation & jurisprudence ; Plant Extracts ; Plant Roots ; Titanium ; United States
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 42
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2002-01-16
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Samyn, Yves -- Massin, Claude -- New York, N.Y. -- Science. 2002 Jan 11;295(5553):276-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11789538" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Classification ; *Ecosystem ; Invertebrates/classification ; Plants/classification ; *Publishing
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 43
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2002-03-16
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sanchez, Pedro A -- New York, N.Y. -- Science. 2002 Mar 15;295(5562):2019-20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉International Center for Research in Agroforestry, Post Office Box 30677, Nairobi, Kenya. P.sanchez@cgiar.org〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11896257" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Africa South of the Sahara ; Agriculture/*methods ; Biomass ; Crops, Agricultural/*growth & development ; *Ecosystem ; Fertilizers ; *Food Supply ; Forestry ; Humans ; Hunger ; Nitrogen ; Nitrogen Fixation ; Phosphates ; Plant Development ; Public Policy ; *Soil ; Trees/growth & development ; United Nations ; Zea mays/growth & development
    Print ISSN: 0036-8075
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 44
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2003-03-22
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mitchell, Charles E -- Reich, Peter B -- New York, N.Y. -- Science. 2003 Mar 21;299(5614):1844-5; author reply 1844-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12649464" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Atmosphere ; Biomass ; California ; *Carbon Dioxide ; Climate ; *Ecosystem ; Fungi/pathogenicity ; Nitrogen ; *Plant Diseases ; Plant Roots/growth & development ; Poaceae/*growth & development/*microbiology ; Temperature
    Print ISSN: 0036-8075
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 45
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2002-03-23
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stone, Richard -- New York, N.Y. -- Science. 2002 Mar 22;295(5563):2191.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11910078" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Commerce/economics ; Conservation of Natural Resources ; *Ecosystem ; *Fishes/physiology ; *Food Supply/economics/standards ; Marine Biology ; Oceans and Seas ; Russia
    Print ISSN: 0036-8075
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 46
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2002-03-23
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Withgott, Jay -- New York, N.Y. -- Science. 2002 Mar 22;295(5563):2201-2.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11910088" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Australia ; Biomass ; California ; *Ecosystem ; Environment ; Food Chain ; Herbicides/administration & dosage/pharmacology ; Mediterranean Region ; Seawater/*parasitology ; Seaweed/drug effects/*physiology
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 47
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2002-09-28
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Malakoff, David -- New York, N.Y. -- Science. 2002 Sep 27;297(5590):2196.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12351768" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Arizona ; *Ecosystem ; Maps as Topic ; *Pinus ; *Trees
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 48
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2003-07-26
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lubick, Naomi -- New York, N.Y. -- Science. 2003 Jul 25;301(5632):451.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12881542" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Atlantic Ocean ; Conservation of Natural Resources ; DNA, Mitochondrial/genetics ; *Ecosystem ; Female ; Genetic Variation ; Genetics, Population ; Male ; Mutation ; Population Density ; Population Dynamics ; Time Factors ; *Whales/genetics
    Print ISSN: 0036-8075
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 49
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2003-07-26
    Beschreibung: It is well known that hunting dramatically reduced all baleen whale populations, yet reliable estimates of former whale abundances are elusive. Based on coalescent models for mitochondrial DNA sequence variation, the genetic diversity of North Atlantic whales suggests population sizes of approximately 240,000 humpback, 360,000 fin, and 265,000 minke whales. Estimates for fin and humpback whales are far greater than those previously calculated for prewhaling populations and 6 to 20 times higher than present-day population estimates. Such discrepancies suggest the need for a quantitative reevaluation of historical whale populations and a fundamental revision in our conception of the natural state of the oceans.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Roman, Joe -- Palumbi, Stephen R -- New York, N.Y. -- Science. 2003 Jul 25;301(5632):508-10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12881568" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Atlantic Ocean ; Base Sequence ; Conservation of Natural Resources ; DNA, Mitochondrial/genetics ; *Ecosystem ; Female ; Genetic Variation ; Genetics, Population ; Male ; Molecular Sequence Data ; Population Density ; Population Dynamics ; Time Factors ; *Whales/classification/genetics
    Print ISSN: 0036-8075
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 50
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2003-03-15
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Webster, Paul -- New York, N.Y. -- Science. 2003 Mar 14;299(5613):1642.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12637710" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Arctic Regions ; Canada ; *Ecosystem ; Environmental Exposure/*adverse effects ; Environmental Pollutants/*analysis ; Female ; Humans ; Infant ; Infection/epidemiology/etiology ; *Inuits ; Memory ; Risk Factors
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 51
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2003-10-25
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stokstad, Erik -- Vogel, Gretchen -- New York, N.Y. -- Science. 2003 Oct 24;302(5645):542-3.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/14576384" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Beta vulgaris/genetics/growth & development ; Biotechnology ; Brassica napus/genetics/growth & development ; Crops, Agricultural/*genetics/growth & development ; *Ecosystem ; *Environment ; Great Britain ; Herbicides ; *Plants, Genetically Modified/growth & development ; Zea mays/genetics/growth & development
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 52
    Publikationsdatum: 2003-03-29
    Beschreibung: Volcanic aerosols from the 1991 Mount Pinatubo eruption greatly increased diffuse radiation worldwide for the following 2 years. We estimated that this increase in diffuse radiation alone enhanced noontime photosynthesis of a deciduous forest by 23% in 1992 and 8% in 1993 under cloudless conditions. This finding indicates that the aerosol-induced increase in diffuse radiation by the volcano enhanced the terrestrial carbon sink and contributed to the temporary decline in the growth rate of atmospheric carbon dioxide after the eruption.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gu, Lianhong -- Baldocchi, Dennis D -- Wofsy, Steve C -- Munger, J William -- Michalsky, Joseph J -- Urbanski, Shawn P -- Boden, Thomas A -- New York, N.Y. -- Science. 2003 Mar 28;299(5615):2035-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Environmental Sciences Division, Building 1509, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6335, USA. lianhong-gu@ornl.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12663919" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Aerosols ; *Atmosphere ; *Carbon Dioxide/metabolism ; Climate ; *Ecosystem ; Mathematics ; Models, Statistical ; Nonlinear Dynamics ; Philippines ; *Photosynthesis ; Regression Analysis ; Scattering, Radiation ; Seasons ; Sunlight ; Temperature ; Trees/*metabolism ; *Volcanic Eruptions
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 53
    Publikationsdatum: 2003-08-16
    Beschreibung: Geochemical anomalies and growth discontinuities in Porites corals from western Sumatra, Indonesia, record unanticipated reef mortality during anomalous Indian Ocean Dipole upwelling and a giant red tide in 1997. Sea surface temperature reconstructions show that although some past upwelling events have been stronger, there were no analogous episodes of coral mortality during the past 7000 years, indicating that the 1997 red tide was highly unusual. We show that iron fertilization by the 1997 Indonesian wildfires was sufficient to produce the extraordinary red tide, leading to reef death by asphyxiation. These findings highlight tropical wildfires as an escalating threat to coastal marine ecosystems.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Abram, Nerilie J -- Gagan, Michael K -- McCulloch, Malcolm T -- Chappell, John -- Hantoro, Wahyoe S -- New York, N.Y. -- Science. 2003 Aug 15;301(5635):952-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia. nerilie.abram@anu.edu.au〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12920295" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Anthozoa/*growth & development ; Atmosphere ; Biomass ; Dinoflagellida/growth & development ; *Ecosystem ; *Eutrophication ; *Fires ; Indian Ocean ; Indonesia ; Iron ; Phytoplankton/growth & development ; Population Dynamics ; Temperature
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  • 54
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2003-12-20
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Elena, Santiago F -- Sanjuan, Rafael -- New York, N.Y. -- Science. 2003 Dec 19;302(5653):2074-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Instituto de Biologia Molecular y Celular de Plantas, Consejo Superior de Investigaciones Cientificas-UPV, 46022 Valencia, Spain. sfelena@ibmcp.upv.es〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/14684807" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): *Adaptation, Physiological ; Animals ; *Biological Evolution ; Chlamydomonas/physiology ; Darkness ; *Ecosystem ; Environment ; *Genetic Variation ; Genotype ; Light ; Mutation ; Phenotype ; Pseudomonas fluorescens/genetics/*physiology ; RNA Viruses/physiology ; Selection, Genetic
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 55
    Publikationsdatum: 2003-12-04
    Beschreibung: The net ecosystem exchange of carbon dioxide was measured by eddy covariance methods for 3 years in two old-growth forest sites near Santarem, Brazil. Carbon was lost in the wet season and gained in the dry season, which was opposite to the seasonal cycles of both tree growth and model predictions. The 3-year average carbon loss was 1.3 (confidence interval: 0.0 to 2.0) megagrams of carbon per hectare per year. Biometric observations confirmed the net loss but imply that it is a transient effect of recent disturbance superimposed on long-term balance. Given that episodic disturbances are characteristic of old-growth forests, it is likely that carbon sequestration is lower than has been inferred from recent eddy covariance studies at undisturbed sites.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Saleska, Scott R -- Miller, Scott D -- Matross, Daniel M -- Goulden, Michael L -- Wofsy, Steven C -- da Rocha, Humberto R -- de Camargo, Plinio B -- Crill, Patrick -- Daube, Bruce C -- de Freitas, Helber C -- Hutyra, Lucy -- Keller, Michael -- Kirchhoff, Volker -- Menton, Mary -- Munger, J William -- Pyle, Elizabeth Hammond -- Rice, Amy H -- Silva, Hudson -- New York, N.Y. -- Science. 2003 Nov 28;302(5650):1554-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA. saleska@fas.harvard.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/14645845" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Brazil ; Carbon/*analysis/metabolism ; Carbon Dioxide/*analysis/metabolism ; Confidence Intervals ; *Ecosystem ; Oxygen Consumption ; Photosynthesis ; Rain ; *Seasons ; *Trees/growth & development/metabolism ; Wood
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 56
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2003-05-10
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kerr, Richard A -- New York, N.Y. -- Science. 2003 May 9;300(5621):885.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12738825" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Ascomycota ; Charcoal ; Climate ; *Ecosystem ; Feces/microbiology ; Geologic Sediments ; Humans ; Madagascar ; *Mammals ; New York ; *Paleontology ; Pollen ; Population Dynamics ; *Spores, Fungal
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 57
    Publikationsdatum: 2003-01-11
    Beschreibung: In the Pacific Ocean, air and ocean temperatures, atmospheric carbon dioxide, landings of anchovies and sardines, and the productivity of coastal and open ocean ecosystems have varied over periods of about 50 years. In the mid-1970s, the Pacific changed from a cool "anchovy regime" to a warm "sardine regime." A shift back to an anchovy regime occurred in the middle to late 1990s. These large-scale, naturally occurring variations must be taken into account when considering human-induced climate change and the management of ocean living resources.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chavez, Francisco P -- Ryan, John -- Lluch-Cota, Salvador E -- Niquen C, Miguel -- New York, N.Y. -- Science. 2003 Jan 10;299(5604):217-21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Monterey Bay Aquarium Research Institute, 7700 Sandholdt Road, Moss Landing, CA 95039, USA. chfr@mbari.org〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12522241" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Atmosphere ; Birds ; Carbon Dioxide ; *Climate ; *Ecosystem ; *Fishes ; Pacific Ocean ; *Seawater ; Temperature ; Time Factors
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 58
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2003-08-23
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Malakoff, David -- New York, N.Y. -- Science. 2003 Aug 22;301(5636):1034-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12933987" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Anthozoa ; Atlantic Ocean ; Conservation of Natural Resources ; *Ecosystem ; Environment ; Fisheries ; *Fishes ; Geologic Sediments ; *Marine Biology ; Pacific Ocean ; *Seawater
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 59
    Publikationsdatum: 2003-09-06
    Beschreibung: The finding that microbial communities are active under snow has changed the estimated global rates of biogeochemical processes beneath seasonal snow packs. We used microbiological and molecular techniques to elucidate the phylogenetic composition of undersnow microbial communities in Colorado, the United States. Here, we show that tundra soil microbial biomass reaches its annual peak under snow, and that fungi account for most of the biomass. Phylogenetic analysis of tundra soil fungi revealed a high diversity of fungi and three novel clades that constitute major new groups of fungi (divergent at the subphylum or class level). An abundance of previously unknown fungi that are active beneath the snow substantially broadens our understanding of both the diversity and biogeochemical functioning of fungi in cold environments.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schadt, Christopher W -- Martin, Andrew P -- Lipson, David A -- Schmidt, Steven K -- New York, N.Y. -- Science. 2003 Sep 5;301(5638):1359-61.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309-0334, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12958355" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Ascomycota/classification/genetics/growth & development/isolation & purification ; Basidiomycota/classification/genetics/growth & development/isolation & ; purification ; Bayes Theorem ; Biomass ; *Cold Climate ; Colorado ; DNA, Fungal/analysis/genetics ; *Ecosystem ; Fungi/*classification/genetics/*growth & development/isolation & purification ; Phylogeny ; *Seasons ; Snow ; *Soil Microbiology
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 60
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2003-06-21
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chick, John H -- Maher, Robert J -- Burr, Brooks M -- Thomas, Matthew R -- New York, N.Y. -- Science. 2003 Jun 20;300(5627):1876-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12817125" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Aquaculture ; Bivalvia ; *Carps/classification ; Conservation of Natural Resources ; *Ecosystem ; Fresh Water ; Illinois
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 61
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2003-03-29
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Swart, Jac A A -- New York, N.Y. -- Science. 2003 Mar 28;299(5615):1981-2; author reply 1981-2.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12663896" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Conservation of Natural Resources/*economics ; Cost-Benefit Analysis ; *Ecosystem ; Financial Management
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    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 62
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2003-10-18
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chivian, Eric -- Roberts, Callum M -- Bernstein, Aaron S -- New York, N.Y. -- Science. 2003 Oct 17;302(5644):391.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/14563988" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Anthozoa ; Biomedical Research ; Conotoxins ; *Conservation of Natural Resources ; *Ecosystem ; Environment ; *Snails
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 63
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 1998-08-15
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ginsberg, H S -- Hyland, D E -- Hu, R -- New York, N.Y. -- Science. 1998 Jul 17;281(5375):349-50.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9705710" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Ecosystem ; Forestry ; Ixodes/*physiology ; New York ; Nymph/physiology ; Population Dynamics ; Rhode Island ; *Trees
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 64
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 1998-03-21
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pennisi, E -- New York, N.Y. -- Science. 1998 Mar 6;279(5356):1445.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9508717" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Biotechnology ; Brazil ; *Ecosystem ; Ownership/economics/*legislation & jurisprudence
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 65
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 1999-07-17
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Appenzeller, T -- New York, N.Y. -- Science. 1999 Jun 25;284(5423):2108-10.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10409068" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): *Adaptation, Physiological ; *Biological Evolution ; Culture Media ; *Ecosystem ; Escherichia coli/*genetics/physiology ; Glucose/metabolism ; Maltose/metabolism ; *Mutation ; Pseudomonas fluorescens/*genetics/physiology ; Selection, Genetic
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 66
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 1999-04-09
    Beschreibung: In a seminal paper, Garrett Hardin argued in 1968 that users of a commons are caught in an inevitable process that leads to the destruction of the resources on which they depend. This article discusses new insights about such problems and the conditions most likely to favor sustainable uses of common-pool resources. Some of the most difficult challenges concern the management of large-scale resources that depend on international cooperation, such as fresh water in international basins or large marine ecosystems. Institutional diversity may be as important as biological diversity for our long-term survival.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ostrom, E -- Burger, J -- Field, C B -- Norgaard, R B -- Policansky, D -- ESO 5022/ES/NIEHS NIH HHS/ -- New York, N.Y. -- Science. 1999 Apr 9;284(5412):278-82.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for the Study of Institutions, Population, and Environmental Change and Workshop in Political Theory and Policy Analysis, Indiana University, Bloomington, IN 47408, USA. ostrom@indiana.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10195886" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): *Conservation of Natural Resources ; *Ecosystem ; Government ; Ownership ; Private Sector ; Privatization ; *Public Policy ; Public Sector ; Social Responsibility
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 67
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 1999-06-26
    Beschreibung: Interactions between species are as evolutionarily malleable as the species themselves and have played a central role in the diversification and organization of life. This malleability creates complex geographic mosaics in interspecific interactions that can evolve rapidly over decades, blurring the distinction between evolutionary time and ecological time and making the study of coevolution crucial for human health and welfare.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Thompson, J N -- New York, N.Y. -- Science. 1999 Jun 25;284(5423):2116-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Departments of Botany and Zoology, Washington State University, Pullman, WA 99164, USA. jnt@wsu.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10381869" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Biological Evolution ; Drug Resistance, Microbial ; *Ecosystem ; Humans ; Models, Biological ; Parasites/pathogenicity ; *Selection, Genetic ; Virulence/genetics
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 68
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2000-09-30
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sinclair, A R -- Ludwig, D -- Clark, C W -- New York, N.Y. -- Science. 2000 Sep 15;289(5486):1875.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11012354" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Conservation of Natural Resources/methods ; *Ecosystem ; Humans ; Residence Characteristics
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 69
    Publikationsdatum: 2000-06-10
    Beschreibung: Globally, tropical deforestation releases 20 to 30% of anthropogenic greenhouse gases. Conserving forests could reduce emissions, but the cost-effectiveness of this mechanism for mitigation depends on the associated opportunity costs. We estimated these costs from local, national, and global perspectives using a case study from Madagascar. Conservation generated significant benefits over logging and agriculture locally and globally. Nationally, however, financial benefits from industrial logging were larger than conservation benefits. Such differing economic signals across scales may exacerbate tropical deforestation. The Kyoto Protocol could potentially overcome this obstacle to conservation by creating markets for protection of tropical forests to mitigate climate change.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kremen, C -- Niles, J O -- Dalton, M G -- Daily, G C -- Ehrlich, P R -- Fay, J P -- Grewal, D -- Guillery, R P -- New York, N.Y. -- Science. 2000 Jun 9;288(5472):1828-32.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Conservation Biology, Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA. ckremen@stanford.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10846165" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Agriculture ; Carbon ; Conservation of Natural Resources/*economics ; Cost-Benefit Analysis ; Developed Countries ; Developing Countries ; *Ecosystem ; Greenhouse Effect ; Industry ; Madagascar ; *Trees
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 70
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2000-08-05
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Brownell, R L Jr -- Curry, B E -- Van Bonn, W -- Ridgway, S H -- New York, N.Y. -- Science. 2000 Jun 30;288(5475):2319-20.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10917829" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Animals, Wild ; California ; Communicable Diseases/transmission/*veterinary ; *Conservation of Natural Resources ; *Ecosystem ; *Seals, Earless
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 71
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2000-09-23
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Starck, W -- New York, N.Y. -- Science. 2000 Sep 8;289(5485):1691.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11001734" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Australia ; *Cnidaria ; Conservation of Natural Resources ; *Disasters ; *Ecosystem ; Humans
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 72
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2000-08-05
    Beschreibung: Researchers have uncovered new evidence about the long-range, and potentially long-term, ecological damage being wrought by an invasive species of fire ant. The red imported fire ant Solenopsis invicta displaces other ant species and upsets the structures of native communities of ants--disruptions that appear to be permanent, they report in the July issue of Ecology Letters. The drop in biodiversity could represent a significant loss, experts note, because of the critical role ants play in recycling nutrients and other biological material.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pennisi, E -- New York, N.Y. -- Science. 2000 Jul 14;289(5477):231.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10917841" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Ants/physiology ; *Ecosystem ; United States
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 73
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2000-07-06
    Beschreibung: To halt the dramatic alteration in our climate, there must be a reduction in the emission of greenhouse gases. As Bonnie and colleagues discuss in their Perspective, conservation of forests will increase carbon sequestration and decrease greenhouse gas emissions. In this issue, a cost-benefit analysis by Kremen et al. demonstrates the benefits of forest conservation on a local and global scale.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bonnie, R -- Schwartzman, S -- Oppenheimer, M -- Bloomfield, J -- New York, N.Y. -- Science. 2000 Jun 9;288(5472):1763-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Environmental Defense, 1875 Connecticut Avenue, NW, Washington, DC 20009, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10877697" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Agriculture ; Carbon ; Conservation of Natural Resources/*economics ; Cost-Benefit Analysis ; Developing Countries ; *Ecosystem ; Greenhouse Effect ; Industry ; *Trees
    Print ISSN: 0036-8075
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 74
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2000-07-07
    Beschreibung: The analysis of major changes in faunal diversity through time is a central theme of analytical paleobiology. The most important sources of data are literature-based compilations of stratigraphic ranges of fossil taxa. The levels of error in these compilations and the possible effects of such error have often been discussed but never directly assessed. We compared our comprehensive database of trilobites to the equivalent portion of J. J. Sepkoski Jr.'s widely used global genus database. More than 70% of entries in the global database are inaccurate; however, as predicted, the error is randomly distributed and does not introduce bias.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Adrain, J M -- Westrop, S R -- New York, N.Y. -- Science. 2000 Jul 7;289(5476):110-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Geoscience, University of Iowa, Iowa City, IA 52242, USA. jonathan-adrain@uiowa.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10884223" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Arthropods/anatomy & histology/*classification ; *Classification ; *Databases, Factual ; *Ecosystem ; *Fossils ; Paleontology/*methods ; Reproducibility of Results
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 75
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2000-07-15
    Beschreibung: A half-century policy of forest exploitation and monoculture in China has led to disastrous consequences, including degradation of forests and landscapes, loss of biodiversity, unacceptable levels of soil erosion, and catastrophic flooding. A new forest policy had been adopted in China called the Natural Forest conservation Program (NFCP), which emphasizes expansion of natural forests and increasing the productivity of forest plantations. Through locally focused management strategies, biodiversity and forest resources will be sustained, and downstream regions will be better protected from flooding. This new policy is being implemented with a new combination of policy tools, including technical training and education, land management planning, mandatory conversion of marginal farmlands to forest, resettlement and retaining of forest dwellers, share in private ownership, and expanded research. These policy tools may have wider relevance for other countries, particularly developing countries.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zhang, P -- Shao, G -- Zhao, G -- Le Master, D C -- Parker, G R -- Dunning, J B Jr -- Li, Q -- New York, N.Y. -- Science. 2000 Jun 23;288(5474):2135-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Natural Forest Conservation and Management, State Forestry Administration (SFA), Beijing 100714, P. R. China.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10896587" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Agriculture ; China ; *Conservation of Natural Resources ; *Ecosystem ; *Forestry/education ; *Public Policy ; Research ; *Trees
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 76
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2001-02-07
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Saikkonen, K -- New York, N.Y. -- Science. 2000 Mar 17;287(5460):1887.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, University of Turku, Finland. karisaik@utu.fi〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10755931" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): *Ecosystem ; Fungi/*physiology ; Poaceae/growth & development/*microbiology ; Symbiosis
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 77
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2000-06-17
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lovett, R A -- New York, N.Y. -- Science. 2000 Jun 2;288(5471):1578-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10858135" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Amphibians ; Animals ; *Ecosystem ; Geological Phenomena ; Geology ; Mammals ; Plant Development ; Urodela ; *Volcanic Eruptions ; Washington
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 78
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2000-11-04
    Beschreibung: Construction of four dams on the lower Snake River (in northwestern United States) between 1961 and 1975 altered salmon spawning habitat, elevated smolt and adult migration mortality, and contributed to severe declines of Snake River salmon populations. By applying a matrix model to long-term population data, we found that (i) dam passage improvements have dramatically mitigated direct mortality associated with dams; (ii) even if main stem survival were elevated to 100%, Snake River spring/summer chinook salmon (Oncorhynchus tshawytscha) would probably continue to decline toward extinction; and (iii) modest reductions in first-year mortality or estuarine mortality would reverse current population declines.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kareiva, P -- Marvier, M -- McClure, M -- New York, N.Y. -- Science. 2000 Nov 3;290(5493):977-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉National Marine Fisheries Service, Northwest Fisheries Science Center, 2725 Montlake Boulevard East, Seattle, WA 98112, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11062128" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Conservation of Natural Resources ; *Ecosystem ; Female ; Fresh Water ; Male ; Models, Biological ; Models, Statistical ; Northwestern United States ; Population Dynamics ; *Salmon/growth & development/physiology ; Survival Rate
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 79
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2000-05-16
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kaiser, J -- New York, N.Y. -- Science. 2000 May 5;288(5467):785-6.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10809640" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; California ; *Ecosystem ; *Plant Development ; Poaceae/*growth & development ; Seeds/growth & development
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 80
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2001-02-24
    Beschreibung: Contrary to conventional wisdom, warmer ocean waters are a greater threat to coral reefs than local environmental insults. That assessment comes from a new scientific report released this week that documents a sudden and steep jump in damage stemming from the 1997-98 El Nino-La Nina event.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Normile, D -- New York, N.Y. -- Science. 2000 Oct 27;290(5492):682-3.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11184189" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Climate ; Cnidaria/*physiology ; *Ecosystem ; Fishes ; Industry ; Oceans and Seas ; Temperature ; Water Pollution
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 81
    Publikationsdatum: 2000-05-29
    Beschreibung: Fully mapped tree census plots of large area, 25 to 52 hectares, have now been completed at six different sites in tropical forests, including dry deciduous to wet evergreen forest on two continents. One of the main goals of these plots has been to evaluate spatial patterns in tropical tree populations. Here the degree of aggregation in the distribution of 1768 tree species is examined based on the average density of conspecific trees in circular neighborhoods around each tree. When all individuals larger than 1 centimeter in stem diameter were included, nearly every species was more aggregated than a random distribution. Considering only larger trees (〉/= 10 centimeters in diameter), the pattern persisted, with most species being more aggregated than random. Rare species were more aggregated than common species. All six forests were very similar in all the particulars of these results.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Condit, R -- Ashton, P S -- Baker, P -- Bunyavejchewin, S -- Gunatilleke, S -- Gunatilleke, N -- Hubbell, S P -- Foster, R B -- Itoh, A -- LaFrankie, J V -- Lee, H S -- Losos, E -- Manokaran, N -- Sukumar, R -- Yamakura, T -- New York, N.Y. -- Science. 2000 May 26;288(5470):1414-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Tropical Forest Science, Smithsonian Tropical Research Institute, Unit 0948, APO AA 34002-0948, USA. ctfs@tivoli.si.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10827950" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Central America ; *Ecosystem ; India ; Malaysia ; Panama ; Sri Lanka ; Statistics as Topic ; Thailand ; *Trees ; Tropical Climate
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 82
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2000-10-14
    Beschreibung: The Kyoto protocol aims to reduce carbon emissions into the atmosphere. Part of the strategy is the active management of terrestrial carbon sinks, principally through afforestation and reforestation. In their Perspective, Schulze et al. argue that the preservation of old-growth forests may have a larger positive effect on the carbon cycle than promotion of regrowth.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schulze, D E -- Wirth, C -- Heimann, M -- New York, N.Y. -- Science. 2000 Sep 22;289(5487):2058-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Max Planck Institute for Biogeochemistry, Post Office Box 100164, 07701 Jena, Germany. Detlef.Schulze@bgc-jena.mpg.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11032555" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): *Carbon ; *Carbon Dioxide ; *Conservation of Natural Resources ; *Ecosystem ; *Trees
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 83
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2001-02-24
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Malakoff, D -- New York, N.Y. -- Science. 2000 Dec 8;290(5498):1873.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11187039" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Cnidaria ; Conservation of Natural Resources/*legislation & jurisprudence ; *Ecosystem ; Hawaii
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 84
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2000-01-22
    Beschreibung: Emerging infectious diseases (EIDs) of free-living wild animals can be classified into three major groups on the basis of key epizootiological criteria: (i) EIDs associated with "spill-over" from domestic animals to wildlife populations living in proximity; (ii) EIDs related directly to human intervention, via host or parasite translocations; and (iii) EIDs with no overt human or domestic animal involvement. These phenomena have two major biological implications: first, many wildlife species are reservoirs of pathogens that threaten domestic animal and human health; second, wildlife EIDs pose a substantial threat to the conservation of global biodiversity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Daszak, P -- Cunningham, A A -- Hyatt, A D -- New York, N.Y. -- Science. 2000 Jan 21;287(5452):443-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Ecology, University of Georgia, Athens, GA 30602, USA. daszak@uga.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10642539" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Agriculture ; Animals ; Animals, Domestic ; *Animals, Wild ; Climate ; Communicable Diseases/epidemiology/etiology/transmission/*veterinary ; Conservation of Natural Resources ; Disease Reservoirs ; *Ecosystem ; Humans ; Zoonoses
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 85
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2000-08-19
    Beschreibung: At a press conference on 27 July, the National Marine Fisheries Service (NMFS) released a long-awaited plan to save the Columbia River's endangered salmon by restoring fish habitat, overhauling hatcheries, limiting harvest, and improving river flow. What the plan did not do, however, was call for immediate breaching of four dams on the Snake River, the Columbia's major tributary--an option that has been the subject of a nationwide environmental crusade. The NMFS will hold that option in abeyance while it sees whether the less drastic measures will do the trick. Responses from both sides were immediate and outraged.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mann, C C -- Plummer, M L -- New York, N.Y. -- Science. 2000 Aug 4;289(5480):716-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10950712" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Conservation of Natural Resources ; *Ecosystem ; Fisheries ; Fresh Water ; Government Agencies ; Northwestern United States ; *Salmon
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 86
    Publikationsdatum: 2000-03-31
    Beschreibung: Recent time-series measurements of atmospheric O2 show that the land biosphere and world oceans annually sequestered 1.4 +/- 0.8 and 2.0 +/- 0.6 gigatons of carbon, respectively, between mid-1991 and mid-1997. The rapid storage of carbon by the land biosphere from 1991 to 1997 contrasts with the 1980s, when the land biosphere was approximately neutral. Comparison with measurements of delta13CO2 implies an isotopic flux of 89 +/- 21 gigatons of carbon per mil per year, in agreement with model- and inventory-based estimates of this flux. Both the delta13C and the O2 data show significant interannual variability in carbon storage over the period of record. The general agreement of the independent estimates from O2 and delta13C is a robust signal of variable carbon uptake by both the land biosphere and the oceans.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Battle, M -- Bender, M L -- Tans, P P -- White, J W -- Ellis, J T -- Conway, T -- Francey, R J -- New York, N.Y. -- Science. 2000 Mar 31;287(5462):2467-70.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Geoscience, Guyot Hall, Princeton University, Princeton, NJ 08544 USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10741962" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): *Atmosphere ; Carbon/*analysis/*metabolism ; Carbon Dioxide/analysis/metabolism ; Carbon Isotopes ; *Ecosystem ; Nitrogen/analysis ; Oceans and Seas ; Oxygen/*analysis ; Oxygen Consumption ; Photosynthesis
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 87
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2000-05-08
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Batke, C -- Haszprunar, G -- Kohler, J -- Naumann, C -- Schminke, H K -- Turkay, M -- New York, N.Y. -- Science. 2000 Apr 28;288(5466):617-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10798997" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Classification ; Conservation of Natural Resources ; *Ecosystem ; Fund Raising ; Research Support as Topic ; *Terminology as Topic
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 88
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2000-03-11
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Davis, M A -- New York, N.Y. -- Science. 2000 Feb 18;287(5456):1203.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10712150" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): *Conservation of Natural Resources ; *Ecosystem ; North America ; Terminology as Topic ; *Trees
    Print ISSN: 0036-8075
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 89
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2001-02-07
    Beschreibung: The relationship between the number of species and the area sampled is one of the oldest and best-documented patterns in community ecology. Several theoretical models and field data from a wide range of plant and animal taxa suggest that the slope, z, of a graph of the logarithm of species richness against the logarithm of area is roughly constant, with z approximately 0.25. We collected replicated and randomized plant data at 11 spatial scales from 0.01 to 10(8) square meters in Great Britain which show that the slope of the log-log plot is not constant, but varies systematically with spatial scale, and from habitat to habitat at the same spatial scale. Values of z were low (0.1 to 0.2) at small scales (〈100 square meters), high (0.4 to 0.5) at intermediate scales (1 hectare to 10 square kilometers), and low again (0.1 to 0.2) for the largest scale transitions (e.g., East Berks to all of Berkshire). Instead of one process determining changes in species richness across a wide range of scales, different processes might determine plant biodiversity at different spatial scales.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Crawley, M J -- Harral, J E -- New York, N.Y. -- Science. 2001 Feb 2;291(5505):864-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Natural Environment Research Council Centre for Population Biology, Imperial College, Silwood Park, Ascot SL5 7PY, UK. m.crawley@ic.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11157164" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): *Ecosystem ; England ; Mathematics ; Plant Physiological Phenomena ; *Plants ; Population Dynamics
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 90
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2001-03-10
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gittleman, J L -- Gompper, M E -- New York, N.Y. -- Science. 2001 Feb 9;291(5506):997-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology,University of Virginia,Charlottesville,Virginia 22903, USA. JLGittleman@virginia.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11232588" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Artiodactyla ; *Behavior, Animal ; Biological Evolution ; *Carnivora ; *Conservation of Natural Resources ; Cues ; *Deer ; *Ecosystem ; *Predatory Behavior ; Ursidae ; Wolves
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 91
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2001-07-31
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Baragona, K -- New York, N.Y. -- Science. 2001 Jul 27;293(5530):603-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11476087" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; China ; *Conservation of Natural Resources ; *Ecosystem ; *Environment ; *Ursidae
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 92
    Publikationsdatum: 2001-09-29
    Beschreibung: Late Pleistocene changes in oceanic primary productivity along the equator in the Indian and Pacific oceans are revealed by quantitative changes in nanoplankton communities preserved in nine deep-sea cores. We show that variations in equatorial productivity are primarily caused by glacial-interglacial variability and by precession-controlled changes in the east-west thermocline slope of the Indo-Pacific. The precession-controlled variations in productivity are linked to processes similar to the Southern Oscillation phenomenon, and they precede changes in the oxygen isotopic ratio, which indicates that they are not the result of ice sheet fluctuations. The 30,000-year spectral peak in the tropical Indo-Pacific Ocean productivity records is also present in the Antarctica atmospheric CO2 record, suggesting an important role for equatorial biological productivity in modifying atmospheric CO2.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Beaufort, L -- de Garidel-Thoron, T -- Mix, A C -- Pisias, N G -- New York, N.Y. -- Science. 2001 Sep 28;293(5539):2440-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉CNRS-CEREGE, BP 80, 13545 Aix-en-Provence Cedex 04, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11577233" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Atmosphere ; Carbon Dioxide ; *Climate ; *Ecosystem ; *Eukaryota ; *Fossils ; Indian Ocean ; Light ; Marine Biology ; Oxygen Isotopes ; Pacific Ocean ; *Plankton ; Seawater ; Time
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 93
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2001-02-13
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Dambacher, J M -- Rossignol, P A -- Li, H W -- Emlen, J M -- New York, N.Y. -- Science. 2001 Feb 9;291(5506):939.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR 97331, USA. dambacherj@fsl.orst.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11161208" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Conservation of Natural Resources ; *Ecosystem ; Fresh Water ; Models, Biological ; Models, Statistical ; Northwestern United States ; Population Dynamics ; *Salmon/growth & development/physiology ; Survival Rate
    Print ISSN: 0036-8075
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    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 94
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2001-11-10
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kaiser, J -- New York, N.Y. -- Science. 2001 Nov 9;294(5545):1268-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11701908" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Ecosystem ; *Environmental Pollutants ; Humans ; International Cooperation ; *Nitrogen/metabolism ; Policy Making
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 95
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2001-09-22
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kaiser, J -- New York, N.Y. -- Science. 2001 Sep 21;293(5538):2199.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11567123" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Birds ; Central America ; *Conservation of Natural Resources ; *Ecosystem ; England ; Environment ; Population Dynamics ; Sciuridae/genetics ; Scotland ; Trees
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 96
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2001-11-21
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Grayson, D K -- New York, N.Y. -- Science. 2001 Nov 16;294(5546):1459-62.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11713777" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Body Weight ; Computer Simulation ; *Ecosystem ; *Human Activities ; Humans ; *Mammals ; Mathematics ; *Paleontology ; Population Dynamics ; Population Growth
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2001-06-09
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Dayton, L -- New York, N.Y. -- Science. 2001 Jun 8;292(5523):1819.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11397924" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Australia ; Biological Evolution ; *Birds ; Computer Simulation ; *Ecosystem ; Geologic Sediments ; Human Activities ; Humans ; *Mammals ; North America ; *Paleontology ; Population Dynamics ; Time
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2001-09-22
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kaiser, J -- New York, N.Y. -- Science. 2001 Sep 21;293(5538):2196-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11567122" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Central America ; *Conservation of Natural Resources ; *Ecosystem ; Environment ; International Cooperation ; Mexico ; Politics
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
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  • 99
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2001-07-28
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kaiser, J -- New York, N.Y. -- Science. 2001 Jul 27;293(5530):624-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11474094" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Agriculture ; Animals ; Databases, Factual ; *Ecology ; *Ecosystem ; Government Agencies ; International Cooperation ; Internet ; Plants ; Research Support as Topic ; Software ; Time Factors ; Trees ; Weather
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2001-06-30
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Thacker, P -- New York, N.Y. -- Science. 2001 Jun 29;292(5526):2427.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11431551" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animal Husbandry ; Animals ; *Animals, Wild ; *Cattle ; *Ecosystem ; Midwestern United States ; Poaceae ; *Sciuridae ; United States ; Wyoming
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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