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Ultrastructural demonstration of NAD-pyrophosphorylase activity (E.C.2.7.7.1) in isolated mouse liver nuclei was investigated with the use of an electronhistochemical procedure based on the precipitation of pyrophosphate ions with lead ions under conditions permitting simultaneous ATPase inhibition by formaldehyde/ethanol prefixation. In isolated mouse liver nuclei activity of NAD-pyrophosphorylase was found in nucleoli, in interchromatin granules, coiled bodies and strand-like structures in nucleoplasm. 相似文献
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Sheila Polakoff 《BMJ (Clinical research ed.)》1987,294(6578):1031-1032
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Robert M. Levin Penelope A. Longhurst Sheila S. Levin Niels Haugaard Alan J. Wein 《Molecular and cellular biochemistry》1990,97(2):153-159
The urinary bladder depends on intracellular ATP for the support of a number of essential intracellular processes including contraction. The concentration of ATP is maintained constant primarily via the rapid transfer of a phosphate from creatine phosphate (CP) to ADP catalyzed by the enzyme creatine kinase (CK). Since muscular pathologies associated with diabetes are in part related to intracellular alterations in metabolism, we have characterized the CK activity in both skeletal muscle and urinary bladder from control and streptozotocin-diabetic rats.The following is a summary of the results: 1) Bladder tissue from control rats showed linear kinetics with a Vmax = 390 nmoles/mg protein/min, and a Km = 275 µM. 2) Urinary bladder tissue isolated from diabetic rats displayed biphasic kinetics with Vmax = 65 and 324 nmoles/mg protein/min, and Km's = 10 µM and 190 µM respectively. 3) Skeletal muscle isolated from control rats showed linear kinetics with an approximate Vmax of 800 nmoles/mg protein/min and a Km of 280 µM CP. 4) Homogenates of skeletal muscle from diabetic rats showed complex kinetics not separable into distict component forms. 5) The Km for ADP for both skeletal muscle and bladder was approximately 10 µM.These studies demonstrate that whereas bladders isolated from both control and diabetic rats possess a low-affinity isomer(s) of CK with similar maximum enzymatic activity, there is a high affinity isomer present within the urinary bladder muscle of diabetic rats that is not present in bladder tissue isolated from control rats. Skeletal muscle isolated from both diabetic and control rats exhibited a maximal activity 2 to 3 times higher than that of the bladder. 相似文献
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Mapping of the bcl-2 oncogene on mouse chromosome 1 总被引:1,自引:0,他引:1
B A Mock D Givol L A D'Hoostelaere K Huppi M F Seldin N Gurfinkel T Unger M Potter J F Mushinski 《Cytogenetics and cell genetics》1988,47(1-2):11-15
Two bcl-2 alleles have been identified in inbred strains of mice by restriction fragment length polymorphism (RFLP). Analysis of a bcl-2 RFLP in a series of bilineal congenic strains (C.D2), developed as a tool for chromosomal mapping studies, revealed linkage of bcl-2 to the Idh-1/Pep-3 region of murine chromosome 1. The co-segregation of bcl-2 alleles with allelic forms of two other chromosome 1 loci, Ren-1,2 and Spna-1, in a set of back-cross progeny, positions bcl-2 7.8 cM centromeric from Ren-1,2. 相似文献
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Formation of double-walled microtubules and multilayered tubulin sheets by basic proteins 总被引:1,自引:0,他引:1
E Unger K J B?hm H Müller H Grossman H Fenske W Vater 《European journal of cell biology》1988,46(1):98-104
Some basic proteins enable microtubule protein to form special assembly products in vitro, known as double-walled microtubules. Using histones (H1, core histones) as well as the human encephalitogenic protein to induce the formation of double-walled microtubules, we made the following electron microscopic observations: (1) Double-walled microtubules consist of an "inner" microtubule which is covered by electron-dense material, apparently formed from the basic protein, and by a second tubulin wall. (2) The tubulin of the second wall seems to be arranged as protofilaments, surrounding the inner microtubule in a helical or ring-like manner. (3) The surface of double-walled microtubules lacks the projections of microtubule-associated proteins, usually found on microtubules. (4) In the case of protofilament ribbons (incomplete microtubules), H1 binds exclusively to their convex sides that correspond to the surface of microtubules. Zn2+-induced tubulin sheets, consisting in contrast to microtubules of alternately arranged protofilaments, are covered by H1 on both surfaces. Furthermore, multilayered sheet aggregates appeared. The results indicate that the basic proteins used interact only with that protofilament side which represents the microtubule surface. In accordance with this general principle, models on the structure of double-walled microtubules and multilayered tubulin sheets were derived. 相似文献
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A bacteriophage-associated glycanase cleaving beta-pyranosidic linkages of 3-deoxy-D-manno-2-octulosonic acid (KDO) 总被引:1,自引:0,他引:1
F Altmann B Kwiatkowski S Stirm L M?rz F M Unger 《Biochemical and biophysical research communications》1986,136(1):329-335
A bacteriophage growing on Escherichia coli K13, K20, and K23 strains carries a glycanase that catalyzes the hydrolytic cleavage of the beta-ketopyranosidic linkages of 3-deoxy-D-manno-2-octulosonic acid (KDO) in the respective capsular polysaccharides. The main cleavage product of the K23 polysaccharide has been identified by 1H- and 13C-n.m.r. spectroscopy as beta beta Ribfl----7 beta KDOp2----3-beta Ribfl----7KDO. Cleavage of polysaccharides containing alpha-pyranosidic, or 5-substituted beta-pyranosidic KDO is not catalyzed by the enzyme. 相似文献