ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Springer  (21)
  • Wiley  (6)
  • Oxford University Press
  • 1995-1999
  • 1990-1994  (27)
  • 1985-1989
  • 1980-1984
  • 1970-1974
  • 1991  (10)
  • 1990  (17)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 20 (1990), S. 677-685 
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electrochemical d.c. and a.c. measurements have been carried out on porous Raney nickel in H2-saturated 0.1 M, 1 M, and 6 M NaOH solutions atT=303 K and 333 K using rotating-disc and static-plaar electrodes. For comparison, measurements were also performed on graphite-cloth and graphite-felt electrodes. From polarization curves and current transients obtained in the potential range of the hydrogen evolution and hydrogen oxidation reactions the dependence of the electrocatalytic activity of Raney nickel on the prepolarization conditions was studied. Impedance spectra in the frequency range 1 mHzf 10 kHz were used to determine the characteristic pore parameters and to identify the kinetic behaviour of the porous electrodes by application of transfer function analysis using non-linear fit routines.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-0983
    Keywords: Glutathione ; Heavy metals ; Phytochelatins ; Fission yeast ; Cadmium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Sixty glutathione-deficient mutants (gsh −) of Schizosaccharomyces pombe have been isolated by their resistance towards the mutagen N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) and their sensitivity to the heavy metal Cadmium (Cd). fifty-three mutants show glutathione contents of less than 5% compared with the wild-type. The residual glutathione contents correlate with the resistance to MNNG, with the sensitivity to Cd and with the growth rate in minimal medium. The gsh −, Cd-sensitive (Cd s) mutants also show sensitivity to other heavy metals. Wild-type strains, but not the gsh − mutants, are able to excrete the heavy metal, very likely as a sulfide-containing compound. This inability of the mutants to excrete Cd and other heavy metals causes an increase in Cd accumulation in the gsh − mutants versus the wild-type. In 60% of the mutants the glutathione deficiency is very likely due to a deficiency in the enzyme glutathione synthetase (GS), the other 40% appear to be deficient in gamma-glutamyl-cysteine synthetase (GCS).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 86 (1991), S. 243-250 
    ISSN: 1432-1939
    Keywords: Daphnia ; Life-history ; Genetics ; Variation ; Maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Life-history traits of 101 clones from two populations of Daphnia magna were measured under controlled environmental conditions in the laboratory. Some individuals had four juvenile instars, others had five. This depended on their length at birth and on the population they came from. Females in the group with five juvenile instars were smaller at birth but larger and older at maturity than those with four juvenile instars. Within groups of females with equal numbers of preadult instars (instar groups) age and size at maturity increased with size at birth. This relationship differed significantly among instar groups for both age and size at maturity. Significant differences in age and size at maturity between two populations became non-significant when size at birth was used as a covariable in AN-COVA. Within populations, size at birth depended on the clone and on the parity of the clutch. First-clutch offspring were considerably smaller than those from later clutches. The results suggest that variability in life-history traits is common within and between clones, but that most of this variation can be accounted for by size at birth and the number of pre-adult instars.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Description / Table of Contents: Zusammenfassung Am Beispiel rhythmischer Abduktions-Adduktionsbewegungen in Schulter- und Hüftgelenken konnten wir Änderungen im zeitlichen Atemablauf nachweisen, die als Phänomene zentralnervöser Koordination im Sinne v. Holsts gedeutet werden können. Sie traten in über 75% aller registrierten Atemzüge auf, wobei der Kopplungsgrad abhängig ist von Art und Anzahl periodisch bewegter Extremitäten, außerdem davon, ob ein äußerer Zeitgeber (akustisches Signal) für den Bewegungsrhythmus existiert oder nicht. Die Befunde weisen darauf hin, daß Reaktionen des motorischen Atemapparates nicht allein in Zusammenhang mit dessen homöostatischer Aufgabe und mit mechanischen Einflüssen interpretiert werden können. Die Steuerung der Atemmotorik erscheint eingeordnet in ein gesamtmotorisches Steuerungssystem. Damit wird auch ein Einfluß der Atemmotorik auf beliebige Skelettmotorik möglich. Koordination führt zur Ausbildung stabiler zeitlicher Beziehungen zwischen Atmung und zusätzlicher Bewegung, deren möglicher Nutzen in einer “energetischen Ökonomisierung” (Hildebrandt 1967) bestehen könnte.
    Notes: Abstract We found modulations in the time-course of breathing during rhythmic abduction-adduction movements in shoulder and hip joints which can be interpreted as phenomena of central coordination in the sense of v. Holst. They occurred in more than 75% of the recorded breaths. The strength of this coordination depends on number and kind of limbs moving rhythmically and on the use of an acoustic trigger signal (“Zeitgeber”) for the limb rhythm as well. Our findings indicate that reactions of the respiratory apparatus cannot be regarded only in connection with its homeostatic function and with mechanical influences. Breathing control appears integrated in the whole organism's “motor control system”. Therefore, an influence of breathing movements on other motor processes is possible as well. Coordination leads to a stable temporal order between breathing and additional movements. Its possible advantage could be an energetic economization as may be concluded from analogous phenomena in coupled non-linear oscillators.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1432-1041
    Keywords: Emiglitate (BAY o 1248) ; sucrose ; starch ; postprandial hyperglycaemia ; glucosidase inhibitor ; blood glucose ; serum insulin ; serum GIP ; breath hydrogen ; adverse effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The absorbable deoxynojirimycin derivative emiglitate (BAY o 1248) is a potent competitive inhibitor of small intestinal α-glucosidases in man. In two similar randomized, placebo-controlled, double blind investigations, the efficacy, duration of action and tolerability of single doses of 10, 20 and 40 mg emiglitate have been assessed in healthy male volunteers after repeated sucrose or maize-starch loads at 08.00, 12.00 and 17.00 h. Even at the lowest dose used, emiglitate almost abolished the glycaemic (−88%) and hormonal responses after the first sucrose meal, simultaneously evoking significant hydrogen evolution (mean peak H2-concentration 〉100 ppm), which was not related to the dose, and which induced unacceptable symptoms of carbohydrate malabsorption, i.e. at the dosages tested, the inhibition of glycaemic and hormonal responses was at the expense of intolerable gastrointestinal adverse effects. Flattening of postprandial responses of blood glucose, serum insulin and gastric inhibitory polypeptide was still apparent after a second sucrose load 4 h later, demonstrating long-lasting inhibition of α-glucosidase activity. After starch, the dose dependency of inhibition emerged more clearly than after sucrose, i.e. the reduction was less pronounced. However, emiglitate led to significant reduction of the glycaemic and hormonal rises after both the first and second starch meals. Symptoms of carbohydrate malabsorption were absent after 10 mg and were negligible with 20 mg or 40 mg emiglitate. Breath hydrogen concentration increased gradually, indicating slight but significant carbohydrate malabsorption after the highest dose of the α-glucosidase inhibitor. The results show that a single morning dose of 20–40 mg emiglitate might be useful in the control of postprandial hyperglycaemia after breakfast and lunch. This dose of the inhibitor was effective after either both 50 g starch or 50 g sucrose as the substrate, but was only tolerable after the starch meal.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several lines of evidence in the literature indicate that environmental stress such as starvation may initiate reallocation of sea urchin endoskeletal tissue. For example, Aristotle's lantern enlarges under conditions of starvation, and sea urchins tagged with tetracycline and then fed develop a distinct growth line, while starved individuals develop a diffuse pattern. We designed anin vivo system to examine stress-related changes in calcification in the purple sea urchinStrongylocentrotus purpuratus. SmallS. purpuratus (ca. 2 cm test diam) were collected from the Mission Bay jetty or Imperial Beach (San Diego, California, USA) in 1987.45Ca was incorporated from seawater into all body fractions including the organic tissue/coelomic fluid. In an initial experiment, sea urchins were fed or starved for 4 wk and then post-incubated in isotope. Overall, starved individuals deposited new calcite more slowly than did fed individuals; however, allocation was very different and calcification of teeth of starved sea urchins was nearly as great as in fed individuals. In a second experiment,S. purpuratus were first pre-labeled with isotope and then treated by feeding or starving. More of the labeled calcium was mobilized from the soft tissues and coelomic fluid into calcite in fed than in starved individuals. Growth of the teeth in starved sea urchins was significantly greater than in those fed. We conclude that starvation changes the metabolism of calcium in order to preferentially build teeth. However, we also found no evidence that calcium was resorbed from “old” skeletal calcite in order to build “new” skeleton.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 25 (1990), S. 223-232 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract By means of EPR, susceptibility, EMP, light-microscopic, thermal and chemical methods the influence of production conditions and subsequent treatments on glassy-phase-containing corundum materials were studied. Melting of the system (Al2O3, SiO2, Na2O, Fe3O4) under reductive conditions leads to a reduction of Fe3+ species contained to Fe2+ and even to Fe0 clusters with ferromagnetic behaviour. Both species markedly influence the mechanical properties of the material by increase of their volumes in consequence of oxidation in subsequent thermal processes. The following model with regard to the localization of the iron species in the system ensues: Fe(III) in corundum, Fe2O3, Fe3O4 and (scarcely) in the glassy phase; Fe(II) in the glassy phase, FeAl2O4 (hercynite) as a solid solution in corundum, and Fe3O4; (Fe0) clusters in corundum. It is therefore not surprising that grinding of the compact material considerably alters the magnetic properties of the samples.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 14 (1990), S. 815-824 
    ISSN: 1573-5028
    Keywords: Agrobacterium tumefaciens ; hypocotyls ; Nicotiana alata ; regeneration ; self-incompatibility ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A transformation and regeneration system has been developed for Nicotiana alata, a plant which is being intensively studied as a model of gametophytic self-incompatibility. Plantlets can be regenerated efficiently from seedling hypocotyls. Kanamycin-resistant, transformed plants have been obtained by cocultivation of regenerating hypocotyls with Agrobacterium tumefaciens strain LBA4404 containing a binary vector. The transformation frequency was low with 〈1% of tissue explants regenerating transformed plants. The transformed plants contained from one to three copies of the introduced DNA. In most cases, the kanamycin resistance phenotype was transmitted to the offspring as a normal Mendelian factor. In one unusual case, none of the offspring inherited the kanamycin resistance of the transformed maternal parent. This plant may have been chimeric or the kanamycin resistance gene may have been inactivated.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of experimental biology and medicine 110 (1990), S. 1540-1543 
    ISSN: 1573-8221
    Keywords: subpopulations of lymphocytes ; cytochemistry ; heterologous graft versus host reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 268 (1990), S. 1141-1147 
    ISSN: 1435-1536
    Keywords: Ultracentrifuge ; sedimentation-equilibriumrun ; poly-L-lysine ; N ε -methylated-poly-L-lysine ; anions ; molecularweight ; 2.virialcoef. ; part.specvolume andassociation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The aim of this work is to investigate the dependence of the molecular weight and the 2. virial coefficient of poly-L-lysine and N ε -methylated poly-L-lysine in solutions of water-structure-influencing anions. In the case of poly-L-lysine, the ultracentrifugal and CD-spectroscopic measurements show an increasing molecular weight and a complex between poly-L-lysine and the strong-water-structure-breaking anion ClO 4 − . In solutions of structure-forming anions, an independence of the molecular weight from the anion-concentration can be recognized. The 2. virial coefficient of structure-breaking anions is generally higher than for structure-forming anions. At a pH of 10.6, the molecular weight and the 2. virial coefficient is independent of the structure-breaking anion. In NaCH3 SO4 solutions, the tendency of the anion concentration and the molecular weight are parallel. Compared to this behavior, N ε -methylated poly-L-lysine was likewise investigated; it shows a similar trend of the molecular weight in dependence of the NaCH3 SO4 concentration.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...