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  • Articles  (14)
  • Wiley-Blackwell  (13)
  • American Geophysical Union  (1)
  • American Geophysical Union (AGU)
  • American Meteorological Society (AMS)
  • 1985-1989  (7)
  • 1980-1984  (7)
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  • Articles  (14)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 192 (1987), S. 27-42 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fate and possible roles of the cytoskeleton in the process of conjugation in the hyptrich ciliate Euplotes aediculatus were investigated. Following the coalescence of the plasma membranes of the conjugant cells, a fusion zone or bridge of cytoplasm contributed by both partners is constructed. The sub-alveolar microtubule layers of the vegetative cell cortex remain in place to define the fusion zone boundaries after cell union. The initial fusion zone consists primarily of featureless ground cytoplasm; soon the ground plasm becomes crowded with microtubules and anastomosing smooth endoplasmic reticulum, which become displaced only late in conjugation as the migratory pronuclei are exchanged between partners. Fusion zone microtubules, functioning in some undetermined way, may be involved in the nuclear migration. Resorption of the posterior portion of each partner's buccal apparatus results in the degradation of the component cilia within acid phosphatase-positive autophagic bodies. Silver staining for light microscopy shows that the late fusion zone contracts forward from the posterior border, then constricts to separate the conjugants. In some separating pairs remnants of a microfilamentous assembly are seen at the posterior edge of the fusion zone; the full extent of this system may be masked by partial degradation due to osmium tetroxide fixation. Treatment of conjugants for 6 hours with cytochalasin B prevents separation, possibly through inhibition of the actin-like microfilament assembly in the fusion zone. The observations and experiments favor a model of cell separation following conjugation in which the fusion zone is resorbed by motile or contractile processes occurring within or around the fusion bridge itself.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 192 (1987), S. 43-61 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The formation and subsequent dissolution of a common bridge of cytoplasm between conjugating ciliated protozoan cells provides an excellent opportunity to follow the dynamics of the cellular membrane systems involved in this process. In particular, separation of conjugant partners offers the chance to observe, at a fixed site on the cell surface, how the ciliate surface complex of plasma and alveolar membranes (collectively termed the “pellicle”) is constructed. Consequently, cortical and cellular membranes of Euplotes aediculatus were studied by light and electron microscopy through the conjugation sequence. A conjugant fusion zone of shared cytoplasm elaborates between the partner cells within their respective oral fields (peristomes) to include microtubules, cytosol, and a concentrated endoplasmic reticulum (heavily stained by osmium impregnation techniques) that may also be continuous with cortical ER of each cell. Cortical membranes displacd by fusion are autolyzed in acid phosphatase-positive lysosomes in the fusion zone. As conjugants separate, expansion of the plasma membrane may occur through the fusion of vesicles with the plasma membrane, presumably at bare membrane, presumably at bare membrane patches near the fusion zone. The underlying cortical alveolar membranes and their plate-like contents are reconstructed beneath the plasma membrane, apparently by multiple fusions of dense-cored alveolar precursor vesicles (APVs). These precursor vesicles themselves appear to condense directly from the smooth ER present in the fusion zone. No Golgi apparatus was visible in the fusion zone cytoplasm, and no step of APV maturation that might involve the Golgi complex was noted.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 9 (1986), S. 308-309 
    ISSN: 0935-6304
    Keywords: High performance liquid chromatography, HPLC ; Reverse phase ; Internal standard ; Trimellitic anhydride ; Air sample ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 124 (1985), S. 391-396 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The addition of human platelet-derived growth factor (PDGF) to confluent, quiescent cultures of human diploid fibroblasts induced the rapid breakdown of cellular polyphosphoinositides. The levels of 32P-labeled phosphatidylinositol 4,5-bisphosphate (PIP2), phosphatidylinositol 4-phosphate (PIP), and phosphatidylinositol (PI) decreased by 30 to 40% within 1 min after exposure of the cells to PDGF. The levels of PIP and PIP2 returned to their initial values within 3 and 10 min, respectively, after PDGF addition. The level of PI continued to increase after it had returned to control values and was up threefold within 30 min after PDGF addition. In cells prelabeled with myo-[3H]inositol PDGF caused an eightfold increase in the levels of inositol trisphosphate (IP3) within 2 min. Lesser increases, twofold and 1.3-fold, respectively, were seen in levels of inositol bisphosphate (IP2) and inositol monophosphate (IP). Within 10 min after PDGF addition the levels of all three inositol phosphates had decreased to control values. The levels of IP3 measured 2 min after PDGF addition depended on the PDGF concentration and were maximal at 5-10 ng/ml of PDGF. Similar concentrations of PDGF stimulate maximal cell growth and DNA synthesis in these cells.
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  • 5
    ISSN: 0170-2041
    Keywords: Resolution, kinetic ; Chiral tertiary amines ; Chiral esters ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Kinetic Resolutions Starting with rac-Alcohols or rac-Acyl Halides Using Optically Active Inductor BasesIn the reaction of one mole equivalent of achiral acyl halides with two equivalents of rac-alcohols in the presence of one equivalent of an optically active inductor base (tertiary amine) partially optically active esters and partially optically active alcohols are formed, having in some cases high optical purity (60 - 70%). The alcohol moiety of the ester and the unchanged alcohol are of opposite configuration. Treatment of two equivalents of rac-acylhalides with one equivalent of an achiral alcohol and an inductor base also leads to a high degree of optical induction. The carbonic acid moiety in the ester and the unchanged acid are of opposite configuration. The optical induction is influenced a) by the ligands linked to the reaction centers, b) by the relative quantities of the reacting partners, c) by the solvent, and d) by the temperature.
    Notes: Bei der Umsetzung eines Moläquivalents achiraler Carbonsäurehalogenide mit zwei Moläquivalenten rac-Alkoholen entstehen unter Mitwirkung von einem Moläquivalent einer optisch aktiven Induktorbase (tertiäres Amin) partiell optisch aktive Ester sowie partiell optisch aktive Alkohole in zum Teil hoher optischer Reinheit (60 - 70%). Der im Ester gebundene Anteil an Alkohol sowie der nicht umgesetzte Alkohol haben entgegengesetzte Konfiguration. Der Induktionsgrad ist ähnlich hoch, wenn man zwei Moläquivalente eines rac-Carbonsäurehalogenids mit je einem Moläquivalent eines achiralen Alkohols und einer Induktorbase umsetzt. Der Carbonsäureanteil im Ester und die freie Säure haben entgegengesetzte Konfiguration. Die optischen Induktionen werden beeinflußt a) durch die Art der mit den Reaktionszentren verknüpften Liganden, b) durch die relativen Mengen der Reaktionspartner, c) durch das Lösungsmittel und d) durch die Temperatur.
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 481-496 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Water mobility in an acid Nafion® membrane containing ca. 15% water by weight has been studied by high-resolution neutron quasielastic scattering (NQES). The data are analyzed in terms of simple models. On a scale of ca. 10 Å, the water molecules move practically as freely as in bulk water, but their long-range motion is much more hindered. These results are important for an understanding of the relation between the microstructure and the macroscopic properties of these membranes. To our knowledge, this is the first detailed NQES study of the water-polymer interaction problem.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 516 (1984), S. 55-66 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photoelectron Spectroscopy on Niobium IodidesThe photoelectron spectra (AlKα, HeI) of NbI5, NbI4, Nb3I8, Nb6I11, HNb6I11, Nb6I8(CH3NH2)6, Nb6I8(C3H7NH2)6, and Nb are measured and discussed. It is shown that the binding energy of the niobium core levels depends linearly on the oxidation number n (n = I/Nb). The relation BE = 201.8 + 1.07 · n holds for the Nb 3d5/2 level. Using this relation the hydridic character of the hydrogen in HNb6I11 becomes plausible and the increased electron concentration of the Nb6I8 cluster in the compounds Nb6I8(CH3NH2)6 and Nb6I8(C3H7NH2)6 is verified. Energy gaps Eg = 0.40 (0.45) eV are found for Nb6I11(HNb6I11) and for the amines the top of the valence band is 0.70 (CH3NH2) and 0.68 eV (C3H7NH2), resp. below the Fermi level.
    Notes: Es werden die Photoelektronenspektren (AlKα, HeI) von NbI5, NbI4, Nb3I8, Nb6I11, HNb6I11, Nb6I8(CH3NH2)6, Nb6I8(C3H7NH2)6 und Nb gemessen und diskutiert. Es läßt sich zeigen, daß die Bindungsenergie BE der Niob-Rumpfniveaus linear von der Oxydationszahl n (n = I/Nb) abhängt; für das Nb 3d5/2-Niveau ergibt sich die Beziehung BE = 201,8 + 1,07 · n. Durch Anwendung dieser Beziehung wird der hydridartige Charakter des Wasserstoffs in HNb6I11 wahrscheinlich gemacht sowie die Zunahme der Elektronenkonzentration im Nb6I8-Cluster der Verbindungen Nb6I8(CH3NH2)6 und Nb6I8(C3H7NH2)6 belegt. Für Nb6I11(HNb6I11) ergibt sich eine verbotene Zone Eg = 0,40 (0,45) eV, für die Amine ist der Abstand der Oberkante des Valenzbandes zur Fermi-Kante 0,70 (CH3NH2) bzw. 0,68 eV (C3H7NH2).
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 483 (1981), S. 181-192 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Darstellung, Eigenschaften und ESCA-Charakterisierung von Vanadium-Oberflächenverbindungen an Silicagel. IV 2p3/2-Bindungsenergiewerte (BE) von 18 Vanadium-Verbindungen in Sauerstoff- und Chlorumgebung wurden ermittelt. Bindungsenergien in Abhängigkeit von der Oxidationszahl wurden hinsichtlich eines linearen Zusammenhangs kritisch überprüft, um so geeignete Modellverbindungen für Vergleichstandards auswählen zu können.Im allgemeinen beobachtet man bei einer Zunahme der formalen Oxydationszahl auch eine Erhöhung der Bindungsenergiewerte; im Einzelfall kann dies aber durch elektronenschiebende/ziehende Liganden überdeckt werden.Die mit Hilfe eines Computerprogramms durchgeführte Subtraktion des überlagernden O 1s Satellitenpeaks verbesserte die Genauigkeit der Vanadium 2p3/2-Bindungsenergiewerte erheblich in Oberflächenverbindungen.Die gefundenen Bindungsenergiewerte für (≡Si—O)3V=O(I), (≡Si—O)3V(II) und (≡Si—O)3V—(O2) (III) zeigen im Vergleich zu den trägerfreien Standardverbindungen eine BE-Erhöhung um 2,1 eV und damit die ausgeprägte elektronenziehende Wirkung des Trägermaterials auf das Vanadium in Oberflächenverbindungen. Über ESCA-Daten eines Oberflächen-Peroxokomplexes (III) wird zum ersten Male berichtet; einige Folgerungen der Ergebnisse werden diskutiert.
    Notes: Binding energies (BE) of 18 pure vanadium compounds (V 2p3/2 niveau) were measured in selected oxygen and chlorine environments, linearity of BE vs. oxidation states scrutinized and appropriate model compounds chosen as comparative standards.The general trend is an increase of BE with formal oxidation state; in particular, it could be counterbalanced by electron donating/withdrawing ligands on the V atom.A graphical (computerized) background substraction method was utilized to remove an interfering O 1s satellite peak and to enhance accuracy of BE values in surface compounds.BEs of (≡Si—O)3V=O (I), (≡Si—O)3V (II), and (≡Si—O)3V—(O2) (III) were determined. By comparison to standards positive BE shifts of about 2.1 eV were derived indicating the strong electron withdrawing (“electron sink”) effect of the support on V in surface compounds. This is the first reported ESCA data on a surface peroxo complex, (III). Some implications of the results are also discussed.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 483 (1981), S. 193-204 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Darstellung, Eigenschaften und ESCA-Charakterisierung von Vanadium-Oberflächenverbindungen an Silicagel. IIBindungsenergiewerte (BE) und Intensitätsverhältnisse in Vn/SiO2 (n = 3, 4 und 5) in Abhängigkeit von der Vanadium-Konzentration und Liganden L wurden untersucht. Die Ermittlung optimierter Produkte und ESCA-Proben wird beschrieben. Anhand dieser Ergebnisse werden die Bedingungen demonstriert, unter denen ESCA zuverlässige Informationen über feinverteilte Oberflächen-Verbindungen liefern kann.Der geeignete Konzentrationsbereich für wäßrige Dotierungen liegt zwischen 0,4 bis 1,2% VIII und 1,0 bis 1,2% für VV; in nichtwäßrigen (metallorganischen) Präparaten ergeben sogar 0,15 bis 0,4% VIII und 0,4% VV brauchbare Spektren. Die ESCA-Daten des Peroxo-Komplexes (≡Si—O)3V—(O2) (I) Bestätigen diese Trends.Außerordentlich feinverteilte Oberflächen-Verbindungen erhält man aus Dotierungen mit V[N(SiMe3)2]3. Hier ist eine Konzentration von 0,4 bis 0,5% VIII (oder VV) optimal und die obere Grenze.Beweise für die Formulierung von VnSiO2 als dreibeinige Oberflächen-Verbindungen sind zusammengefaßt; die Bedeutung des Additivitätsprinzips für die Erklärung und Voraussage elektronischer Verhältnisse bei Oberflächen-Verbindungen wird erläutert.Innerhalb der Serie (≡SiO)3V—L (mit L = ohne Liganden, =0, und —Oz) wurden die chemischen Verschiebungen für ≡Si—O—V (0,7 eV); V=O (0,6 eV) und V—(O2) (0,4 eV) ermittelt. Die BE-Beiträge einiger Donorliganden (und —Cl) werden abgeschätzt. In (I)deuten die ESCA-Daten eine formale Oxydationszahl nahe +4 an.Grenzen der ESCA-Methode werden erwähnt und Erweiterungen des Additivitätsprinzips diskutiert.
    Notes: Binding energy (BE) behavior and signal intensity as function of V conc. and ligands L were critically examined in Vn/SiO2 species (where n = +5, +4, and +3) and securing of optimized products and ESCA samples is described. The results moreover demonstrate conditions and approaches whereby ESCA can provide reliable information on highly diluted surface compound systems.From aquous media 1.0-1.2 wt. % VV and 0.4-1.2 wt. % VIII proved to be preferred ranges whereas in non aqueous (metalorganic) preparates the surprisingly low concentration of 0.4-0.15 wt. % VIII gave usable spectra and even 0.4 wt. % VV could be measured. ESCA data with the peroxo complex (≡Si—O)3V—(O2) (I) confirmed these trends.Superiorly subdivided surface compounds (reflected in the quality of spectra) are obtainable from V[N(SiMe3)2]3 impregnations where 0.4-0.5 wt. % VIII (or VV) are maximum/optimum conc. limits.Evidence for formulating Vn/SiO2 as three legged surface compounds is summarized and diagnostic/predictive uses of the additivity principle for surface electron states illustrated.In the (≡Si—O)3V—L series, where L = none, =O, and —(O2) positive ΔBE shifts for ≡Si—O—V (0.7 eV); V=O (0.6 eV); and V—(O2) (0.4 eV) were estimated. Tentative BE contributions of some donor ligands (and —Cl) are also suggested. In (I) ESCA indicated a formal oxidation state of approx. +4.Certain limits (precautions) with ESCA are noted and extensions of the additivity relationship discussed.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 462 (1980), S. 177-184 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Transition Metal Alkyl Compounds. XXX. Synthesis and Characterization of Nitrobenzyl Nickel Compounds(C2H5)2Ni · dipy reacts with benzyl chlorides forming complexes of the type RNiCl · dipy. In this way nitro groups containing thermally stable organonickel compounds can be obtained, which cannot be achieved by means of organolithiiim or Grignard reagents. - In a similar way (C2H5)Ni · dipy reacts with to form · dipy.The composition of the compounds achieved was proved by analysis, by characteristic reactions, magnetic moments, and in part by their IR and M spectra.
    Notes: (C2H5)2Ni · dipy reagiert mit Benzylchloriden zu Benzylnickelchlorid-Komplexen des Typs RNiCl · dipy. Auf diesem Wege sind auch Nitrogruppen enthaltende thermisch stabile Organonickelverbindungen zugängig, die mittels Organolithium-oder Grignardverbindungen nicht erhalten werden können. - Auf analoge Weise reagiert (C2H5)2Ni · dipy mit zu · dipy.Die Zusammensetzung der erhaltenen Verbindungen wurde analytisch, durch die magnetischen Momente sowie IR-Daten und M-Spektren und durch charakteristische Reaktionen gesichert.
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