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31.
Inhibition of HIV-1 protease in infected T-lymphocytes by synthetic peptide analogues. 总被引:22,自引:0,他引:22
T D Meek D M Lambert G B Dreyer T J Carr T A Tomaszek M L Moore J E Strickler C Debouck L J Hyland T J Matthews 《Nature》1990,343(6253):90-92
32.
Zusammenfassung Acetylcholin und Pancreozymin induzieren beide eine Depolarisation der Azinuszellmembran in der Bauchspeicheldrüse. Nur die Wirkung von Acetylcholin wird von Atropin blockiert. Das Ruhepotential kann auch durch eine erhöhte Kaliumkonzentration im Extrazellularraum reduziert werden, diese Wirkung wird nicht von Atropin beeinflusst. Die Acetylcholin-induzierte Depolarisation ist nicht von extrazellularer Kalziumkonzentration abhängig, sondern ist wahrscheinlich eine notwendige Bedingung für den Sekretionsprozess.
Supported by grants from The Carlsberg Foundation, The Wellcome Trust and I. and H. Weismann's legat. Present address: Inst. Med. Physiol. C, Univ. Copenhagen, Denmark.
Cholecystokinin-Pancreozymin was kindly provided by GIH research unit, Chemistry Department, Karolinska Institutet, Stockholm. 相似文献
Supported by grants from The Carlsberg Foundation, The Wellcome Trust and I. and H. Weismann's legat. Present address: Inst. Med. Physiol. C, Univ. Copenhagen, Denmark.
Cholecystokinin-Pancreozymin was kindly provided by GIH research unit, Chemistry Department, Karolinska Institutet, Stockholm. 相似文献
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Three-dimensional structure of tosyl-alpha-chymotrypsin 总被引:28,自引:0,他引:28
35.
Regulation of calcium influx by second messengers in rat mast cells 总被引:42,自引:0,他引:42
Biphasic increases in the free intracellular calcium concentration, consisting of a large initial transient followed by a sustained elevation, are frequently observed in non-excitable cells following stimulation. In rat peritoneal mast cells a cAMP- and Ca-activated chloride current can interact with IP3-dependent calcium influx to provide the sustained elevation of intracellular Ca concentration following transient IP3-induced release of calcium from intracellular stores. This novel combination of second messenger systems provides a flexible means to modulate calcium-dependent processes such as exocytosis. 相似文献
36.
A mutant T4 lysozyme displays five different crystal conformations 总被引:14,自引:0,他引:14
Phage T4 lysozyme consists of two domains between which is formed the active-site cleft of the enzyme. The crystallographically determined thermal displacement parameters for the protein suggested that the amino terminal of the two domains undergoes 'hinge-bending' motion about an axis passing through the waist of the molecule. Such conformational mobility may be important in allowing access of substrates to the active site of the enzyme. We report here a crystallographic study of a mutant T4 lysozyme which demonstrates further the conformational flexibility of the protein. A mutant form of the enzyme with a methionine residue (Met 6) replaced by isoleucine crystallizes with four independent molecules in the crystal lattice. These four molecules have distinctly different conformations. The mutant protein can also crystallize in standard form with a structure very similar to the wild-type protein. Thus the mutant protein can adopt five different crystal conformations. The isoleucine for methionine substitution at the intersection of the two domains of T4 lysozyme apparently enhances the hinge-bending motion presumed to occur in the wild-type protein, without significantly affecting the catalytic activity or thermal stability of the protein. 相似文献
37.
Haydon DT Randall DA Matthews L Knobel DL Tallents LA Gravenor MB Williams SD Pollinger JP Cleaveland S Woolhouse ME Sillero-Zubiri C Marino J Macdonald DW Laurenson MK 《Nature》2006,443(7112):692-695
The conventional objective of vaccination programmes is to eliminate infection by reducing the reproduction number of an infectious agent to less than one, which generally requires vaccination of the majority of individuals. In populations of endangered wildlife, the intervention required to deliver such coverage can be undesirable and impractical; however, endangered populations are increasingly threatened by outbreaks of infectious disease for which effective vaccines exist. As an alternative, wildlife epidemiologists could adopt a vaccination strategy that protects a population from the consequences of only the largest outbreaks of disease. Here we provide a successful example of this strategy in the Ethiopian wolf, the world's rarest canid, which persists in small subpopulations threatened by repeated outbreaks of rabies introduced by domestic dogs. On the basis of data from past outbreaks, we propose an approach that controls the spread of disease through habitat corridors between subpopulations and that requires only low vaccination coverage. This approach reduces the extent of rabies outbreaks and should significantly enhance the long-term persistence of the population. Our study shows that vaccination used to enhance metapopulation persistence through elimination of the largest outbreaks of disease requires lower coverage than the conventional objective of reducing the reproduction number of an infectious agent to less than one. 相似文献
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P. F. Han Y. H. Marian H. W. Matthews J. Johnson 《Cellular and molecular life sciences : CMLS》1981,37(7):687-689
Summary Yeast glucose-6-P dehydrogenase is irreversibly inactivated by penicillin G. Kinetic data show that 1 molecule of penicillin G reacts with each active unit when the enzyme is inactivated The rate of inactivation increases greatly with increasing pH. This irreversible inactivation by penicillin G is largely prevented by pyridoxal-P, a reversible inactivator of this enzyme. Prior treatment of penicillin G with penicillinase totally abolishes its ability to inactivate the enzyme.This work was supported by grant RR-8006 from the General Research Branch, Division of Research Resouces, NIH (USA). 相似文献