全文获取类型
收费全文 | 5424篇 |
免费 | 384篇 |
国内免费 | 1篇 |
出版年
2022年 | 30篇 |
2021年 | 58篇 |
2020年 | 21篇 |
2019年 | 34篇 |
2018年 | 51篇 |
2017年 | 58篇 |
2016年 | 71篇 |
2015年 | 121篇 |
2014年 | 146篇 |
2013年 | 290篇 |
2012年 | 266篇 |
2011年 | 273篇 |
2010年 | 152篇 |
2009年 | 163篇 |
2008年 | 252篇 |
2007年 | 248篇 |
2006年 | 282篇 |
2005年 | 247篇 |
2004年 | 282篇 |
2003年 | 234篇 |
2002年 | 251篇 |
2001年 | 196篇 |
2000年 | 180篇 |
1999年 | 191篇 |
1998年 | 77篇 |
1997年 | 82篇 |
1996年 | 52篇 |
1995年 | 51篇 |
1994年 | 64篇 |
1993年 | 48篇 |
1992年 | 108篇 |
1991年 | 111篇 |
1990年 | 102篇 |
1989年 | 83篇 |
1988年 | 78篇 |
1987年 | 64篇 |
1986年 | 91篇 |
1985年 | 84篇 |
1984年 | 86篇 |
1983年 | 67篇 |
1982年 | 48篇 |
1981年 | 46篇 |
1980年 | 37篇 |
1979年 | 52篇 |
1978年 | 38篇 |
1977年 | 34篇 |
1976年 | 30篇 |
1975年 | 17篇 |
1974年 | 27篇 |
1973年 | 24篇 |
排序方式: 共有5809条查询结果,搜索用时 15 毫秒
151.
152.
Expression of gicerin in development, oncogenesis and regeneration of the chick kidney 总被引:1,自引:0,他引:1
153.
Virulent and avirulent Rhodococcus equi infection in T-cell deficient athymic nude mice: pathologic, bacteriologic and immunologic responses 总被引:1,自引:0,他引:1
154.
Hepatitis C virus core protein interacts with the cytoplasmic tail of lymphotoxin-beta receptor. 总被引:22,自引:2,他引:20
下载免费PDF全文
![点击此处可从《Journal of virology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
M Matsumoto T Y Hsieh N Zhu T VanArsdale S B Hwang K S Jeng A E Gorbalenya S Y Lo J H Ou C F Ware M M Lai 《Journal of virology》1997,71(2):1301-1309
Hepatitis C virus (HCV) core protein is a multifunctional protein. We examined whether it can interact with cellular proteins, thus contributing to viral pathogenesis. Using the HCV core protein as a bait to screen a human liver cDNA library in a yeast two-hybrid screening system, we have isolated several positive clones encoding cellular proteins that interact with the HCV core protein. Interestingly, more than half of these clones encode the cytoplasmic domain of lymphotoxin-beta receptor (LT betaR), which is a member of the tumor necrosis factor receptor family. Their binding was confirmed by in vitro glutathione S-transferase fusion protein binding assay and protein-protein blotting assay to be direct and specific. The binding sites were mapped within a 58-amino-acid region of the cytoplasmic tail of LT betaR. The binding site in the HCV core protein was localized within amino acid residues 36 to 91 from the N terminus, corresponding to the hydrophilic region of the protein. In mammalian cells, the core protein was found to be associated with the membrane-bound LT betaR. Since the LT betaR is involved in germinal center formation and developmental regulation of peripheral lymphoid organs, lymph node development, and apoptotic signaling, the binding of HCV core protein to LT betaR suggests the possibility that this viral protein has an immunomodulating function and may explain the mechanism of viral persistence and pathogenesis of HCV. 相似文献
155.
156.
HYS2, an essential gene required for DNA replication in Saccharomyces cerevisiae. 总被引:6,自引:1,他引:5
下载免费PDF全文
![点击此处可从《Nucleic acids research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
To investigate cell cycle regulation at the S or G2 phase in Saccharomyces cerevisiae, we have isolated mutants displaying supersensitivity to hydroxyurea (HU), a chemical that inhibits DNA replication. Such mutants, which we have named hydroxyurea sensitive (hys), defined four linkage groups and we characterized the hys2 mutation in this study. The hys2-1 mutant displays temperature sensitive growth and a constellation of phenotypes indicating defective DNA metabolism. At the restrictive temperature, hys2-1 cells arrest as large budded cells with a single nucleus at the neck of the bud and a short spindle. The hys2-1 mutant exhibits increased rates of chromosome loss and recombination. Additionally, hys2-1 appears to accumulate incompletely replicated DNA that can be detected by a pulse field electrophoresis assay. Finally, deletion of RAD9 in a hys2-1 strain decreases the percentage of arrested cells, suggesting that an intact RAD9-checkpoint is required for the cell cycle arrest in hys2-1 cells. HYS2 encodes a 55 kDa protein that is essential for viability at all temperatures. Taken together, these data suggest that Hys2 plays a role in DNA replication. 相似文献
157.
158.
Summary A medium for the production of 1,2-epoxytetradecane from 1-tetradecene by Nocardia corallina B-276 was optimized. The activity of cells producing 1,2-epoxytetradecane increased when cell growth was suppressed by limiting nitrogen or potassium ion in the medium. Mg2+ was found to be essential for the production of 1,2-epoxide. Cell mass was increased, without reducing production of 1,2-epoxide, by increasing the concentration of yeast extract and limiting the concentration of potassium ion. The concentration of 1,2-epoxytetradecane reached 80 g/l in 6 days after optimization and the yield of 1,2-epoxytetradecane was 65 mol% based on consumed 1-tetradecene. Long chain 1,2-epoxyalkanes containing 13–17 carbon atoms also were produced under these conditions. 相似文献
159.
Michiyoshi Masuda Kimio Isiglo Hideki Yamoka Takafumi Matsumoto Manabu Takahashi 《Biochemical and biophysical research communications》1984,119(3):920-925
The fate of 3H-thymidine incorporated into newly synthesized DNA of CHO cells was analyzed by either the estimation of the incorporated radioactivity per cell or sedimentation in alkaline sucrose gradient. Under conditions in which DNA synthesis proceeded continuously, of incorporated radioactivity was periodically lost and regained during a 90 min chase, corresponding to a cyclic change in the sedimentation profiles. When DNA synthesis was inhibited by hydroxyurea no cyclic change of the incorporated radioactivity was observed. The cyclic changes were regarded as the result of an actual metabolic change in3H-labelled DNA probaly joining to one of the newly formed sister strands of DNA and the loss of radioactivity seems to require active continued DNA synthesis. 相似文献
160.
ATPase, especially the Ca2$-dependent enzyme, in the chromatinfraction isolated from nuclei of pea seedlings was activatedby bovine brain calmodulin and by protein that was judged tobe calmodulin from its Ca2$-dependent activation of NAD kinase.This calmodulin-dependent ATPase activity was blocked by calmodulin-specificinhibitors. (Received July 11, 1983; Accepted October 24, 1983) 相似文献