全文获取类型
收费全文 | 21570篇 |
免费 | 1136篇 |
国内免费 | 7篇 |
出版年
2021年 | 230篇 |
2020年 | 131篇 |
2019年 | 181篇 |
2018年 | 258篇 |
2017年 | 241篇 |
2016年 | 371篇 |
2015年 | 580篇 |
2014年 | 687篇 |
2013年 | 1433篇 |
2012年 | 1241篇 |
2011年 | 1209篇 |
2010年 | 795篇 |
2009年 | 763篇 |
2008年 | 1231篇 |
2007年 | 1255篇 |
2006年 | 1176篇 |
2005年 | 1170篇 |
2004年 | 1164篇 |
2003年 | 1130篇 |
2002年 | 1042篇 |
2001年 | 507篇 |
2000年 | 494篇 |
1999年 | 489篇 |
1998年 | 312篇 |
1997年 | 218篇 |
1996年 | 201篇 |
1995年 | 175篇 |
1994年 | 164篇 |
1993年 | 178篇 |
1992年 | 330篇 |
1991年 | 306篇 |
1990年 | 260篇 |
1989年 | 244篇 |
1988年 | 220篇 |
1987年 | 210篇 |
1986年 | 197篇 |
1985年 | 190篇 |
1984年 | 173篇 |
1983年 | 150篇 |
1982年 | 148篇 |
1981年 | 107篇 |
1980年 | 111篇 |
1979年 | 109篇 |
1978年 | 105篇 |
1977年 | 90篇 |
1976年 | 88篇 |
1975年 | 82篇 |
1974年 | 56篇 |
1973年 | 79篇 |
1970年 | 63篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
Escherichia coli disruptants defective in the yaeM gene, which is located at 4.2 min on the chromosome map, were constructed and characterized. The disruptants showed auxotrophy for 2-C-methylerythritol, a free alcohol of 2-C-methyl-D-erythritol 4-phosphate that is a biosynthetic precursor in the nonmevalonate pathway. This result clearly shows that the yaeM gene is indeed involved in this pathway in E. coli. 相似文献
6.
Takashi Arakawa Yoshiaki Kamiya 《Biochemical and biophysical research communications》2010,397(2):345-349
We previously reported the identification of DP-1 isoforms (α and β), which are structurally C-terminus-deleted ones, and revealed the low-level expression of these isoforms. It is known that wild-type DP-1 is degraded by the ubiquitin-proteasome system, but few details are known about the domains concerned with the protein stability/instability for the proteolysis of these DP-1 isoforms. Here we identified the domains responsible for the stability/instability of DP-1. Especially, the DP-1 “Stabilon” domain was a C-terminal acidic motif and was quite important for DP-1 stability. Moreover, we propose that this DP-1 Stabilon may be useful for the stability of other nuclear proteins when fused to them. 相似文献
7.
Satoko Iwahori Daisuke Kohmon Junya Kobayashi Yuhei Tani Takashi Yugawa Kenshi Komatsu 《Cell cycle (Georgetown, Tex.)》2014,13(3):471-481
Ataxia-telangiectasia mutated (ATM) plays crucial roles in DNA damage responses, especially with regard to DNA double-strand breaks (DSBs). However, it appears that ATM can be activated not only by DSB, but also by some changes in chromatin architecture, suggesting potential ATM function in cell cycle control. Here, we found that ATM is involved in timely degradation of Cdt1, a critical replication licensing factor, during the unperturbed S phase. At least in certain cell types, degradation of p27Kip1 was also impaired by ATM inhibition. The novel ATM function for Cdt1 regulation was dependent on its kinase activity and NBS1. Indeed, we found that ATM is moderately phosphorylated at Ser1981 during the S phase. ATM silencing induced partial reduction in levels of Skp2, a component of SCFSkp2 ubiquitin ligase that controls Cdt1 degradation. Furthermore, Skp2 silencing resulted in Cdt1 stabilization like ATM inhibition. In addition, as reported previously, ATM silencing partially prevented Akt phosphorylation at Ser473, indicative of its activation, and Akt inhibition led to modest stabilization of Cdt1. Therefore, the ATM-Akt-SCFSkp2 pathway may partly contribute to the novel ATM function. Finally, ATM inhibition rendered cells hypersensitive to induction of re-replication, indicating importance for maintenance of genome stability. 相似文献
8.
9.
T Kaidoh S Natsuume-Sakai M Takahashi 《Journal of immunology (Baltimore, Md. : 1950)》1981,126(2):463-467
A simple, 3-step method was described for purification of murine C4 binding protein (C4-bp), a recently recognized serum protein that functions as one of the regulatory proteins of the complement system. The method consists of 1) affinity chromatography using TNBS-BGG-conjugated Sepharose beads, 2) gel filtration on a Sepharose 6B column, and 3) heparin-Sepharose chromatography. By this method, milligram quantities of C4-bp can be easily purified by more than 500-fold from EDTA-serum of various mouse strains, and the whole purification process can be completed within 1 wk. The overall yield of C4-bp is about 15%. The C4-bp thus prepared is homogeneous as judged by SDS-polyacrylamide gel electrophoresis and immunelectrophoresis. The purified mouse C4-bp showed physicochemical properties very similar to those described for human C4-bp. Like human C4-bp, mouse C4-bp is composed of several apparently identical subunits of the m.w. of 80,000. However unlike the human counterpart, the subunits of mouse C4-bp are not linked by disulfide bonds but are connected by non-covalent forces that can be disrupted by SDS. The purified mouse C4-bp retained binding affinity for C4 and showed unaltered antigenicity. Immunization of rabbits with the purified mouse C4-bp resulted in the production of potent and monospecific antisera. 相似文献
10.