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  • Chemistry  (64)
  • Structured Biological Modelling  (2)
  • Antisense repression  (1)
  • Class II patatin gene  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Structured biological modelling: a method for the analysis and simulation of biological systems applied to oscillatory intracellular calcium waves
    Amsterdam : Elsevier
    Biosystems 27 (1992), S. 145-169 
    Details
    ISSN: 0303-2647
    Keywords: Oscillatory calcium waves ; Signal transduction ; Stochastic simulation ; Structured Biological Modelling ; Systems analysis
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0303-2647(92)90070-F
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of antisense repression of the chloroplast triose-phosphate translocator on photosynthetic metabolism in transgenic potato plants (1994)
    Springer
    Planta 193 (1994), S. 174-180 
    Details
    ISSN: 1432-2048
    Keywords: Antisense repression ; Photosynthesis ; Solanum ; Starch synthesis ; Triose phosphate translocator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The introduction of an antisense DNA into transgenic potato (Solanum tuberosum L.) plants decreased the expression of the chloroplast triose-phosphate translocator and lowered its activity by 20–30%. With plants propagated from tubers, the effect of the transformation on photosynthetic metabolism was analysed by measuring photosynthesis, the formation of leaf starch, and the total and subcellular metabolite contents in leaves. Although the transformants, in contrast to those propagated from cell cultures, did not differ from the wild-type plants in respect to rates of photosynthesis, plant appearance, growth and tuber production, their photosynthetic metabolism was found to be severely affected. The results show that the decrease in activity of the triose-phosphate translocator in the transformants caused a fourfold increase in the level of 3-phosphoglycerate and a corresponding decrease in inorganic phosphate in the stromal compartment, resulting in a large increase in the synthesis of starch. Whereas during a 12-h day period wild-type plants deposited 43% of their CO2 assimilate into starch, this value rose to 61–89% in the transformants. In contrast to the wild-type plants, where the rate of assimilate export from the leaves during the night period was about 75% of that during the day, the export rate from leaves of transformants appeared to be much higher during the night than during the day. As the mobilisation of starch occurs in part hydrolytically, resulting in the formation of glucose, the triose-phosphate translocator loses its exclusive function in the export of carbohydrates from the chloroplasts when the photoassimilates are temporarily deposited as starch. It appears that by directing the CO2 assimilates mainly into starch, the transformants compensate for the deficiency in triose-phosphate translocator activity in such a way that the productivity of the plants is not affected by the transformation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192527
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  • 3
    Electronic Resource
    Electronic Resource
    Systems analysis in cell biology: From the phenomenological description towards a computer model of the intracellular signal transduction network (1993)
    Springer
    Cellular and molecular life sciences 49 (1993), S. 245-257 
    Details
    ISSN: 1420-9071
    Keywords: Structured analysis ; mathematical modelling ; stochastic simulation ; cell cycle control ; tumor biology ; calcium oscillations ; signal transduction ; Structured Biological Modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In this paper we introduce a systematic approach for the modelling of complex biological systems which is especially useful for the analysis of signal transduction mechanisms in cell biology. It is shown that systems analysis in form of top-down levelled dataflow diagrams provides a powerful tool for the mathematical modelling of the system in terms of a stochastic formulation. Due to the exact formulation, the consistency of the model with the experimental results can be tested by means of a computer simulation. The method termed Structured Biological Modelling (SBM) is illustrated by modelling some aspects of the second messenger network which regulates cell proliferation. As an example for the strainghtforward development of a mathematical description a stochastic computer model for intracellular Ca2+ oscillations is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01923534
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  • 4
    Electronic Resource
    Electronic Resource
    Theory-based improvements of continuous polymer fractionation demonstrated for poly(carbonate) (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 1265-1279 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: For the first time, a quantitative theoretical analysis (liquid/liquid phase equilibria treated by means of the continuous thermodynamics) of the operating characteristics of continuous polymer fractionation (CPF) was performed. The results of these calculations were compared with data published for CPF of polyethylene. It turned out that the efficiency of the conventional CPF corresponds to approximately two theoretical plates only. For this reason, several improvements, suggested by theoretical considerations, were realized experimentally, for which purpose the system dichloromethane/diethylene glycol/bisphenol-A polycarbonate was chosen. The pulsating sieve-bottom column was replaced by a nonpulsating column filled with glass beads. In this manner, the number of theoretical plates could be raised considerably. A further improvement of the fractionation efficiency results from the reflux of part of the polymer contained in the sol phase. In praxi, this situation was realized by putting a condensor on top of the column and introducing the feed somewhere near its upper third. After predictive calculations and orienting experiments, 125 g of a polycarbonate with Mw = 29 kg/mol and a nonuniformity U = 1.3 were fractionated in four consecutive CPF runs (where the gels were directly used as feed for the next step) into five fractions of approximately equal weight. Except for the lowest-molecular-weight fraction, one obtains nonuniformities on the order of 0.1.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070450715
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  • 5
    Electronic Resource
    Electronic Resource
    Thermal fractionation and identification of low-density polyethylenes (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 62 (1996), S. 1339-1345 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In the present publication, a method to identify and distinguish between different types of low-density polyethylene based on thermal fractionation and FTIR analysis is described. It was shown that during thermal fractionation four to seven endothermic peaks are obtained as opposed to one or two peaks obtained during regular differential scanning calorimetric analysis. The ration between band heights at 1368 and 1376 cm-1 was found to represent the length of the side chain (branch). © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Comment on the novel parameter of polymer structure suggested by W. S. Bahary (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 12 (1968), S. 973-974 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1968.070120430
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  • 7
    Electronic Resource
    Electronic Resource
    Continuous fractionation and solution properties of PIB.Part I: cf. Ref. 1. II. CPF optimization (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 34 (1987), S. 287-305 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The quality of polymer fractionation depends on the choice of the mixed solvent as well as on the particular conditions of operating the continuous countercurrent extraction. With a polyisobutylene (PIB) sample of medium molecular weight Mw = 98,400 g/mol and U = (Mw/Mn) - 1 = 1.4 plus the mixed solvents toluene/2-butanone (TOL/MEK) and n-heptane/2-butanone (HEP/MEK) (both giving comparably good fractionation in equilibrium experiments), possible ways to optimize the CPF were tested. The mixed solvent HEP/MEK turns out to be superior to TOL/MEK for kinetic reasons. Due to the larger gap between its density and that of the pure polymer, the coexisting phases can still move through the column, even if the working point of the CPF is chosen close to the consolute point of the ternary system. Under these conditions the mass transfer becomes more rapid, and up to 80% of the (mixed) solvent can be economized as compared with TOL/MEK. Four CPF runs with TOL/MEK (each dividing the polymer material into portions approximately equal in weight, and rejecting the first low molecular fraction) yielded four 200 g samples of Mw ranging from 80,600 to 257,000 with U values of ca. 0.3.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070340124
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  • 8
    Electronic Resource
    Electronic Resource
    Continuous fractionation and solution properties of PIB. I. Search for the best mixed solvent and first results of the continuous polymer fractionation (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 34 (1987), S. 271-285 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: To adopt a recently developed method for large scale fractionation (CPF = continuous polymer fractionation, a special kind of counter current extraction) to polyisobutylene (PIB), a systematic search for the best mixed solvent was performed. For this purpose, the essential parts of the phase diagrams solvent/nonsolvent/PIB were determined for 21 mixed solvents by cloud-point measurements; with eight systems of special interest, the molecular weight distributions of the polymers contained in the coexisting phases were also studied. On the basis of these experiments and of considerations concerning additional criteria for the performance of the continuous counter current extraction, the mixed solvent toluene/methyl ethyl ketone was chosen. First experiments with a PIB sample of Mw = 420,000 g/mol and a molecular nonuniformity U = (Mw/Mn) - 1 of 2.3 yielded two high molecular weight fractions Mw = 1.1 × 106 and 0.6 × 106 resp., with U = 0.3 on a 100 g scale upon the application of four CPF steps.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070340123
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  • 9
    Electronic Resource
    Electronic Resource
    On the factors governing the pressure dependence of the viscosity of moderately concentrated polymer solutionsPart of theses of H. G. and J. R. S. (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 1277-1291 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Viscosity measurements were carried out as a function of pressure and temperature with solutions of polystyrene in eight (endothermal) θ-solvents at the respective critical composition by means of a Searle-type apparatus. A rolling-ball viscometer was used for the investigation of the pure solvents. In all cases the viscosity coefficient increases in a more or less exponential manner when the pressure is raised. For θ-conditions, the volumes of activation of the solutions exceed that of the pure solvent by typically 10-15%. The exact amount of this extra efffect stemming from the presence of the polymer and its variation with temperature can be qualitatively correlated with the heats of mixing. The ratio of the viscosity of the solution at 1000 and 1 bar, respectively, can be varied for a given solvent power (θ-temperature) by the choice of the solvent from ca. 2 (cyclopentane) to 4 (trans-decalin). Within a given system, the maximum effects that can be realized by a change of the solvent power via the variation of temperature ranges from ca. 3 to 6 (tert-butylacetate).
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1982.070270417
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  • 10
    Electronic Resource
    Electronic Resource
    Über die Tieftemperaturform von K3NO3 (1983)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 502 (1983), S. 153-157 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Low-temperature K3NO3Low-temperature Guinier photographs (+20 ← -140°C) indicate a reversible phase-transition at -42°C. From X-ray powder data a structural model based on ordered NO2- groups has been derived (I4cm, a = 726.9(1), c = 1046.3(2) pm).
    Notes: Tieftemperatur-Guinieraufnahmen (+20 ← -140°C) von K3NO3 zeigen eine reversible Phasentransformation bei -42°C an. Aus den Röntgenpulverdaten wird ein Strukturvorschlag abgeleitet (I4cm, a = 726,9(1), c = 1046,3(2) pm), der geordnete NO2--Anionen aufweist.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19835020719
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