全文获取类型
收费全文 | 3616篇 |
免费 | 327篇 |
出版年
2023年 | 16篇 |
2022年 | 23篇 |
2021年 | 62篇 |
2020年 | 38篇 |
2019年 | 47篇 |
2018年 | 71篇 |
2017年 | 54篇 |
2016年 | 82篇 |
2015年 | 200篇 |
2014年 | 191篇 |
2013年 | 250篇 |
2012年 | 288篇 |
2011年 | 293篇 |
2010年 | 179篇 |
2009年 | 148篇 |
2008年 | 233篇 |
2007年 | 216篇 |
2006年 | 217篇 |
2005年 | 180篇 |
2004年 | 160篇 |
2003年 | 137篇 |
2002年 | 148篇 |
2001年 | 51篇 |
2000年 | 50篇 |
1999年 | 57篇 |
1998年 | 56篇 |
1997年 | 26篇 |
1996年 | 24篇 |
1995年 | 30篇 |
1994年 | 33篇 |
1993年 | 27篇 |
1992年 | 32篇 |
1991年 | 38篇 |
1990年 | 25篇 |
1989年 | 40篇 |
1988年 | 17篇 |
1987年 | 30篇 |
1986年 | 13篇 |
1985年 | 9篇 |
1984年 | 16篇 |
1983年 | 12篇 |
1982年 | 9篇 |
1981年 | 10篇 |
1980年 | 6篇 |
1979年 | 10篇 |
1978年 | 6篇 |
1972年 | 6篇 |
1968年 | 6篇 |
1965年 | 6篇 |
1964年 | 7篇 |
排序方式: 共有3943条查询结果,搜索用时 21 毫秒
71.
72.
DNA sequence organization of the beta-globin complex in the BALB/c mouse 总被引:41,自引:0,他引:41
C L Jahn C A Hutchison S J Phillips S Weaver N L Haigwood C F Voliva M H Edgell 《Cell》1980,21(1):159-168
73.
74.
F Jahn Z Gregus A Gyurasics F Varga W Klinger 《Acta biologica et medica Germanica》1982,41(2-3):255-261
Cadmium sulfate x 8/3 H2O (0.3, 0.6, 1.5 and 2.0 mg/kg) administered simultaneously with eosine and bromsulphthalein (120 mumol/kg i.v.) did not significantly change the biliary excretion of the dyes. After a 3 days pretreatment with 2.0 mg/kg CdSO4 i.p. a body weight loss and an increase in the relative liver weight when calculated on body weight were observed together with an enhanced bile flow, but the excretion of the dyes was not markedly influenced. Ethylmorphine N-demethylation and ethoxycoumarin O-deethylation activities as well as microsomal cytochrome P-450 concentration were diminished by about 50%. It can be concluded that in male rats the hepatic microsomal monooxygenase system is more sensitive towards cadmium than the hepatic transport system for organic anions. 相似文献
75.
76.
Association of Rab3A with synaptic vesicles at late stages of the secretory pathway 总被引:17,自引:4,他引:13
M Matteoli K Takei R Cameron P Hurlbut P A Johnston T C Südhof R Jahn P De Camilli 《The Journal of cell biology》1991,115(3):625-633
Rab3A is a small GTP-binding protein highly concentrated on synaptic vesicles. Like other small GTP-binding proteins it is thought to cycle between a soluble and a membrane-associated state. To determine at which stage of the life cycle of synaptic vesicles rab3A is associated with their membranes, the localization of the protein in neurons and neuroendocrine cells at different developmental and functional stages was investigated. In all cases, rab3A was colocalized with synaptic vesicle markers at the cell periphery, but was absent from the Golgi area, suggesting that rab3A associates with vesicles distally to the Golgi complex and dissociates from vesicle membranes before they recycle to this region. Immunofluorescence experiments carried out on frog motor end plates demonstrated that massive exocytosis of synaptic vesicles is accompanied by a translocation of rab3A to the cell surface. The selective localization of rab3A on synaptic vesicles at stages preceding their fusion with the plasmalemma suggests that the protein is part of a regulatory machinery that is assembled onto the vesicles in preparation for exocytosis. 相似文献
77.
Henrik Ærenlund Pedersen 《Nordic Journal of Botany》1992,12(4):387-388
A new name (Pteroceras semiteretifolium H. Æ. Peders.) and two new combinations (P. cladostachyum (Hook.f.) H. Æ. Peders., P. unguiculatum (Lindley) H. Æ. Peders.) are presented. The correct application of the name P. pallidum (Blume) Holttum is discussed. 相似文献
78.
Henrik Kibak Lincoln Taiz Thomas Starke Paul Bernasconi Johann Peter Gogarten 《Journal of bioenergetics and biomembranes》1992,24(4):415-424
Proton pumping ATPases/ATPsynthases are found in all groups of present-day organisms. The structure of V- and F-type ATPases/ATP synthases is very conserved throughout evolution. Sequence analysis shows that the V- and F-type ATPases evolved from the same enzyme already present in the last common ancestor of all known extant life forms. The catalytic and noncatalytic subunits found in the dissociable head groups of the V/F-type ATPases are paralogous subunits, i.e., these two types of subunits evolved from a common ancestral gene. The gene duplication giving rise to these two genes (i.e., encoding the catalytic and noncatalytic subunits) predates the time of the last common ancestor.Mapping of gene duplication events that occurred in the evolution of the proteolipid, the noncatalytic and the catalytic subunits, onto the tree of life leads to a prediction for the likely subunit structure of the encoded ATPases. A correlation between structure and function of V/F-ATPases has been established for present-day organisms. Implications resulting from this correlation for the bioenergetics operative in proto-eukaryotes and in the last common ancestor are presented. The similarities of the V/F-ATPase subunits to an ATPase-like protein that was implicated to play a role in flagellar assembly are evaluated.Different V-ATPase isoforms have been detected in some higher eukaryotes. These data are analyzed with respect to the possible function of the different isoforms (tissue specific, organelle specific) and with respect to the point in their evolution when these gene duplications giving rise to the isoforms had occurred, i.e., how far these isoforms are distributed. 相似文献
79.
We have previously argued from phylogenetic sequence data that the group I intron in the rRNA genes of Tetrahymena was acquired by different Tetrahymena species at different times during evolution. We have now approached the question of intron mobility experimentally by crossing intron+ and intron? strains looking for a strong polarity in the inheritance of the intron (intron homing). Based on the genetic analysis we find that the intron in T. pigmentosa is inherited as a neutral character and that intron+ and intron? alleles segregate in a Mendelian fashion with no sign of intron homing. In an analysis of vegetatively growing cells containing intron+ and intron? rDNA, initially in the same macronucleus, we similarly find no evidence of intron homing. During the course of this work, we observed to our surprise that progeny clones from some crosses contained three types of rDNA. One possible explanation is that T. pigmentosa has two rdn loci in contrast to the single locus found in T. thermophila. Some of the progeny clones from the genetic analysis were expanded for several hundred generations, and allelic assortment of the rDNA was demonstrated by subcloning analysis. © 1992 Wiley-Liss, Inc. 相似文献
80.