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  • 1970-1974  (5)
Collection
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archiv der Mathematik 25 (1974), S. 41-44 
    ISSN: 1420-8938
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial and engineering chemistry 10 (1971), S. 483-489 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1335
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Leber-RNS von männlichen NMRI-Mäusen, die 24 Std nach Injektion von (3H)Methylcarbamat, (2-3H) Äthylcarbamat oder Äthyl-(carboxy-14C)-carbamat durch Phenolextraktion nach Georgiev gewonnen wurde, enthielt carboxyalkyl-markierte Methylbzw. Äthylester der Cytosin-5-carboxylsäure. Die in vivo-Reaktion der Carbamate mit Leber RNS wurde durch Actinomycin D gehemmt. Bei der Fraktionierung durch Dichtegradientenzentrifugation, Polyacrylamidgelelektrophorese sowie Säulenchromatographie über Hydroxylapatit und Methylalbumin-Kieselgur wurde der überwiegende Teil der Aktivität (80%) in den Fraktionen gefunden, die neu synthetisierte RNS enthalten. Es ist deshalb anzunehmen, daß die Cytosin-5-carboxylate aus den Carbamaten oder ihren Metaboliten vor der Inkorporation in die RNS-Kette gebildet werden, oder daß die RNS in der Synthese-Phase gegenüber der Einwirkung chemisch aktiver Carbamatmetabolite empfindlicher ist. Das nicht carcinogene Methylcarbamat wurde dabei etwa 10fach stärker inkorporiert als das carcinogene Äthylcarbamat. Synthese- und Umsatzgeschwindigkeit der Leber-RNS wurden durch beide Carbamate etwa ihrer Inkorporationsrate entsprechend gesteigert.
    Notes: Summary Actinomycin D reduced the in vivo labelling of liver RNA by tritiated methyl or ethyl carbamates. Fractionation of the RNA from mice injected 24 h previously with [3H] methyl carbamate, [2-3H] ethyl carbamate or ethyl [carboxy-14C] carbamate on MAK columns, sucrose density gradients and calcium phosphate columns or by polyacrylamide gel electrophoresis showed radioactive esters of cytosine-5-carboxylic acid to be present in the fractions where rapid RNA synthesis had occurred. This suggests that the cytosine-5-carboxylates were synthesised from these carbamates, or their metabolites, before incorporation into RNA chains or that the rapidly labelled RNA was more susceptible to attack by a chemically active metabolite from the carbamates. There was a greater incorporation of the non-carcinogenic methyl carbamate than of the carcinogenic ethyl carbamate 24h after injection. The methyl ester also caused a more rapid breakdown of RNA than ethyl carbamate, ethyl and probably methyl carbamate also increased RNA synthesis.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Over the last few years a number of fuel-cell power systems of various types and power outputs have been built by Shell Research Ltd. The first of these was a relatively primitive hydrazine-air system built in 1962. The paper will trace the development of these power systems from 1962 to the present day. Emphasis will be placed mainly on the engineering design and development that have been needed to take advantage of the improved catalysts and electrodes. Thus, the methods devised to give adequate fluid flows will be outlined, the simplification of components will be considered and the design of ancillaries will be discussed. Present-day fuel batteries have power densities of up to 130–150 W/kg (60–70 W/lb) and, even with commerically available auxiliaries, complete power systems having power/weight ratios of about 52 W/kg (24 W/lb) can be built. These figures are compared with the power densities of conventional electric generators, and future possibilities are discussed.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Type of Medium: Electronic Resource
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