全文获取类型
收费全文 | 4816篇 |
免费 | 535篇 |
国内免费 | 7篇 |
出版年
2021年 | 54篇 |
2020年 | 34篇 |
2019年 | 53篇 |
2018年 | 62篇 |
2017年 | 59篇 |
2016年 | 73篇 |
2015年 | 151篇 |
2014年 | 187篇 |
2013年 | 205篇 |
2012年 | 245篇 |
2011年 | 243篇 |
2010年 | 157篇 |
2009年 | 127篇 |
2008年 | 221篇 |
2007年 | 213篇 |
2006年 | 219篇 |
2005年 | 216篇 |
2004年 | 230篇 |
2003年 | 219篇 |
2002年 | 217篇 |
2001年 | 108篇 |
2000年 | 104篇 |
1999年 | 92篇 |
1998年 | 78篇 |
1997年 | 46篇 |
1996年 | 63篇 |
1995年 | 52篇 |
1994年 | 51篇 |
1993年 | 45篇 |
1992年 | 90篇 |
1991年 | 69篇 |
1990年 | 79篇 |
1989年 | 57篇 |
1988年 | 62篇 |
1987年 | 71篇 |
1986年 | 53篇 |
1985年 | 66篇 |
1984年 | 66篇 |
1983年 | 52篇 |
1982年 | 59篇 |
1981年 | 44篇 |
1980年 | 54篇 |
1979年 | 54篇 |
1978年 | 37篇 |
1977年 | 50篇 |
1976年 | 34篇 |
1975年 | 38篇 |
1974年 | 52篇 |
1973年 | 50篇 |
1967年 | 34篇 |
排序方式: 共有5358条查询结果,搜索用时 890 毫秒
1.
2.
The effect of insulin on phosphatidylcholine biosynthesis in cultured rat liver cells was assessed by measuring changes in the activity of the first enzyme in the choline pathway of phosphatidylcholine biosynthesis, choline kinase (ATP: cholinephosphortransferase, EC 2.7.1.32), in the presence or absence of the hormone. Choline kinase specific activity in liver cells incubated for 18 hours in the presence of 10?7M insulin increased two-fold from 3.4 ± 0.3 nmoles phosphorylcholine formed/min/mg protein to 7.5 ± 0.6 nmoles/min/mg protein. This effect was dose dependent and reversed by the addition of actinomycin D and cycloheximide. It is concluded that the increase in specific activity is due to synthesis of new enzyme rather than activation of existing enzyme. 相似文献
3.
4.
F Stephen Perry 《BMJ (Clinical research ed.)》1998,317(7156):481
5.
6.
7.
Rad52 recruitment is DNA replication independent and regulated by Cdc28 and the Mec1 kinase 下载免费PDF全文
Rodney Rothstein 《The EMBO journal》2009,28(8):1121-1130
Recruitment of the homologous recombination machinery to sites of double‐strand breaks is a cell cycle‐regulated event requiring entry into S phase and CDK1 activity. Here, we demonstrate that the central recombination protein, Rad52, forms foci independent of DNA replication, and its recruitment requires B‐type cyclin/CDK1 activity. Induction of the intra‐S‐phase checkpoint by hydroxyurea (HU) inhibits Rad52 focus formation in response to ionizing radiation. This inhibition is dependent upon Mec1/Tel1 kinase activity, as HU‐treated cells form Rad52 foci in the presence of the PI3 kinase inhibitor caffeine. These Rad52 foci colocalize with foci formed by the replication clamp PCNA. These results indicate that Mec1 activity inhibits the recruitment of Rad52 to both sites of DNA damage and stalled replication forks during the intra‐S‐phase checkpoint. We propose that B‐type cyclins promote the recruitment of Rad52 to sites of DNA damage, whereas Mec1 inhibits spurious recombination at stalled replication forks. 相似文献
8.
Nataly Mancette Rijensky Netta R. Blondheim Shraga Eilon Barnea Nir Peled Eli Rosenbaum Aron Popovtzer Solomon M. Stemmer Alejandro Livoff Mark Shlapobersky Neta Moskovits Dafna Perry Eitan Rubin Itzhak Haviv Arie Admon 《Molecular & cellular proteomics : MCP》2020,19(8):1360-1374
Highlights
- •Sufficient tumor tissues are often unavailable large HLA peptidome discovery.
- •Using patient derived xenograft (PDX) tumors can overcome this limitation.
- •The large PDX HLA peptidomes expand significantly those of the original biopsies.
- •The HLA peptidomes of the PDX tumors included many tumor antigens.
9.
A new species,Acanthocephaloides cyrusi, is described from the fishesSolea bleekeri andPomadasys commersoni from Lake St. Lucia, Natal, South Africa. It is distinguished from the other species in the genus by the more marked sexual dimorphism in length, the arrangement of hooks, the proboscis with the longest hooks at the anterior-most extremity and the greater size of the proboscis hooks and body spines. An acanthella, which may represent this species, was found in the tanaidApseudes digitalis. 相似文献
10.