全文获取类型
收费全文 | 73549篇 |
免费 | 5966篇 |
国内免费 | 40篇 |
出版年
2021年 | 814篇 |
2020年 | 548篇 |
2019年 | 670篇 |
2018年 | 988篇 |
2017年 | 894篇 |
2016年 | 1492篇 |
2015年 | 2293篇 |
2014年 | 2697篇 |
2013年 | 3523篇 |
2012年 | 4414篇 |
2011年 | 4408篇 |
2010年 | 2905篇 |
2009年 | 2611篇 |
2008年 | 3757篇 |
2007年 | 4004篇 |
2006年 | 3848篇 |
2005年 | 3596篇 |
2004年 | 3555篇 |
2003年 | 3516篇 |
2002年 | 3242篇 |
2001年 | 915篇 |
2000年 | 668篇 |
1999年 | 890篇 |
1998年 | 961篇 |
1997年 | 669篇 |
1996年 | 544篇 |
1995年 | 599篇 |
1994年 | 570篇 |
1993年 | 627篇 |
1992年 | 774篇 |
1991年 | 683篇 |
1990年 | 626篇 |
1989年 | 657篇 |
1988年 | 677篇 |
1987年 | 673篇 |
1986年 | 657篇 |
1985年 | 748篇 |
1984年 | 811篇 |
1983年 | 717篇 |
1982年 | 747篇 |
1981年 | 791篇 |
1980年 | 757篇 |
1979年 | 646篇 |
1978年 | 614篇 |
1977年 | 583篇 |
1976年 | 524篇 |
1975年 | 514篇 |
1974年 | 667篇 |
1973年 | 610篇 |
1970年 | 500篇 |
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
1.
2.
3.
4.
5.
6.
Wendy A. Douglass Robert H. Hyland Christopher D. Buckley Aymen Al-Shamkhani Jacqueline M. Shaw Sarah L. Scarth David L. Simmons S.K.Alex Law 《FEBS letters》1998,440(3):125
The cysteine-rich region (CRR) of the β2 integrin subunit was replaced by that of β1 to give the chimera β2NV1. β2NV1 can combine with αL to form a variant leukocyte-function-associated antigen (LFA)-1 on COS cell surface, suggesting that the specificity of the β2 interaction with αL does not lie in the CRR. Unlike those expressing wild-type LFA-1, COS cells expressing αLβ2NV1 are constitutively active in intercellular adhesion molecule (ICAM)-1 adhesion. These results suggest that activation of LFA-1 involves the release of an intramolecular constraint, which is maintained, in part, by the authentic β2 CRR. 相似文献
7.
Grape thaumatin-like proteins (TLPs) play roles in plant-pathogen interactions and can cause protein haze in white wine unless removed prior to bottling. Different isoforms of TLPs have different hazing potential and aggregation behavior. Here we present the elucidation of the molecular structures of three grape TLPs that display different hazing potential. The three TLPs have very similar structures despite belonging to two different classes (F2/4JRU is a thaumatin-like protein while I/4L5H and H2/4MBT are VVTL1), and having different unfolding temperatures (56 vs. 62°C), with protein F2/4JRU being heat unstable and forming haze, while I/4L5H does not. These differences in properties are attributable to the conformation of a single loop and the amino acid composition of its flanking regions. 相似文献
8.
Robert S. Steneck 《Current biology : CB》2009,19(3):R117-R119
9.
10.
A new simple enzymatic method for measuring AMP content in freeze-clamped rat heart is presented. The method is based on the ammonia estimation after the deamination of 5'-AMP by muscle 5'-adenylic acid deaminase. The minimum detectable amount of AMP was about 1.5 nmol. The recovery of AMP added to the tissue homogenate was 94%. The variance coefficient evaluated by assaying five samples from one tissue extract was equal to 5%. AMP content of rat heart (0.28 mumol/g wet tissue) is comparable with the values reported by others. 相似文献