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81.
Isolation and structural analysis of a peptide containing the novel tyrosyl-glucose linkage in glycogenin. 总被引:5,自引:0,他引:5 下载免费PDF全文
The glucosylation site on glycogenin, the protein primer required for de novo glycogen synthesis, has been identified. The glucose is attached at position C1 in a glycosidic linkage with a unique tyrosine, and the sequence surrounding this residue was found to be: His-Leu-Pro-Phe-Ile-Tyr-Asn-Leu-Ser-Ser-Ile-Ser-Ile-Tyr(Glc)-Ser-Tyr-Leu -Pro- Ala-Phe-Lys. The same tyrosine residue is glycosylated whether glycogenin is isolated as a complex with the catalytic subunit of glycogen synthase, or covalently attached to glycogen. The possibility that insulin and growth factors may enhance glycogen synthesis via stimulation of the priming reaction is discussed. 相似文献
82.
Three-dimensional structure of the regular surface glycoprotein layer of Halobacterium volcanii from the Dead Sea 总被引:2,自引:0,他引:2 下载免费PDF全文
A three-dimensional reconstruction from electron micrographs of negatively stained cell envelopes of Halobacterium volcanii has revealed the structure of the surface glycoprotein to a resolution of 2 nm. The glycoprotein is arranged on a p6 lattice with a lattice constant of 16.8 nm. It forms 4.5 nm high, dome-shaped, morphological complexes with a narrow pore at the apex opening into a `funnel' towards the cell membrane. The polarity of the structure was derived from freeze-etching experiments and `edge' views. Six radial protrusions emanate from each morphological complex and join around the 3-fold axis to provide lateral connectivity. Using the primary structure of the surface glycoprotein of the closely related species Halobacterium halobium (Lechner and Sumper, 1987) and the cell envelope profile from a previous X-ray analysis of the same species (Blaurock et al., 1976) we have integrated our reconstruction into a model of halobacterial cell envelope. 相似文献
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Adam Slivka Mary Beth Spina Harold I. Calvin Gerald Cohen 《Journal of neurochemistry》1988,50(5):1391-1393
Previous studies indicated that DL-buthionine sulfoximine (DL-BSO), an agent that inhibits the biosynthesis of GSH in liver and other peripheral organs, fails to suppress levels of GSH in the CNS. In the current study, preweanling mice responded to repeated injections of L-BSO with marked declines (79.6-86.5%) of GSH content in brain and spinal cord. In adult mice, the same treatment schedule produced only modest declines (17.8-29.2%) of GSH content in brain and a 55.9% decline in spinal cord. Pretreatment of preweanling mice with L-BSO represents a tool for studying the role of GSH in the CNS. 相似文献
88.
Polyacrylamide gel analysis of the structural polypeptides of purified group C virions allowed six major proteins to be identified. Of these, two (52,000- and 39,000-molecular-weight polypeptides) were shown to be in the outer virion shell as judged by the ability to strip them from virions by treatment with EDTA. Treatment of purified particles with endo-beta-N-acetylglucosaminidase F showed that the 39,000-molecular-weight outer shell polypeptide is probably posttranslationally glycosylated. Serological cross-comparison of groups A and C by using Western blotting (immunoblotting) extended the previously demonstrated lack of cross-reaction for the group antigen to show that none of the structural polypeptides cross-reacted. Possible implications of these findings for the epidemiology of rotaviruses are discussed. 相似文献
89.
Antigenic analysis of a major neutralization site of herpes simplex virus glycoprotein D, using deletion mutants and monoclonal antibody-resistant mutants. 总被引:15,自引:14,他引:1 下载免费PDF全文
M I Muggeridge V J Isola R A Byrn T J Tucker A C Minson J C Glorioso G H Cohen R J Eisenberg 《Journal of virology》1988,62(9):3274-3280
Herpes simplex virus glycoprotein D is a component of the virion envelope and appears to be involved in attachment, penetration, and cell fusion. Monoclonal antibodies against this protein can be arranged in groups on the basis of a number of biological and biochemical properties. Group I antibodies are type common, have high complement-independent neutralization titers, and recognize discontinuous (conformational) epitopes; they are currently being used in several laboratories to study the functions of glycoprotein D. We have used a panel of neutralization-resistant mutants to examine the relationships between these antibodies in detail. We found that they can be divided into two subgroups, Ia and Ib, such that mutations selected with Ia antibodies have little or no effect on binding and neutralization by Ib antibodies and vice versa. In addition, Ia antibodies are able to bind deletion and truncation mutants of glycoprotein D that Ib antibodies do not recognize, suggesting that their epitopes are physically distinct. However, with one exception, Ia and Ib antibodies block each other strongly in binding assays with purified glycoprotein D, whereas antibodies from other groups have no effect. We have therefore defined the sum of the Ia and Ib epitopes as antigenic site 1. 相似文献
90.
Delineation of the viral products of recombination in vaccinia virus-infected cells. 总被引:7,自引:5,他引:2 下载免费PDF全文
Plasmids containing the vaccinia virus thymidine kinase gene, its flanking DNA sequences, and the Escherichia coli beta-galactosidase gene were used in conjunction with a thymidine kinase-deficient virus to examine the viral products of recombination. Progeny derived from single-crossover events could be distinguished from those generated by gene conversion or double-crossover events when the beta-galactosidase gene was separated from the thymidine kinase gene by the flanking sequences. Using methotrexate to select for recombinant virus and a chromogenic indicator to detect beta-galactosidase, the generation of viral recombinants was measured over a 48-h period. Recombinant progeny were first observed at 12 h and increased to a maximum of 2.5% at 48 h. Single-crossover products, as determined by beta-galactosidase expression, reached a maximum of 57% of the recombinant population at 24 h and thereafter declined. DNA hybridization analysis was used to examine genomic structures of the progeny of the initial viral plaques, plaques purified three times, and those subject to a 10(4)-fold amplification. These analyses confirmed that single-crossover events within either the 5'- or 3'-homologous flanking sequences generated unstable recombinant structures. These structures were shown to contain a single copy of the intact thymidine kinase gene within the corresponding copy of the duplicated thymidine kinase flanking sequences, separated by the beta-galactosidase gene and plasmid DNA. Significantly, these duplicated structures could undergo further recombination to produce repeats of either the intact or the deleted thymidine kinase sequences. These intermediate structures ultimately degenerated to produce either the parental thymidine kinase-deleted or the wild-type genome. The wild-type genome was also shown to be generated directly by gene conversion or double-crossover events. 相似文献