首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   5638篇
  免费   510篇
  国内免费   349篇
  2024年   4篇
  2023年   426篇
  2022年   157篇
  2021年   233篇
  2020年   300篇
  2019年   220篇
  2018年   271篇
  2017年   221篇
  2016年   268篇
  2015年   328篇
  2014年   300篇
  2013年   458篇
  2012年   298篇
  2011年   298篇
  2010年   260篇
  2009年   324篇
  2008年   211篇
  2007年   235篇
  2006年   222篇
  2005年   181篇
  2004年   153篇
  2003年   124篇
  2002年   117篇
  2001年   100篇
  2000年   77篇
  1999年   99篇
  1998年   78篇
  1997年   59篇
  1996年   56篇
  1995年   55篇
  1994年   45篇
  1993年   47篇
  1992年   41篇
  1991年   41篇
  1990年   24篇
  1989年   25篇
  1988年   21篇
  1987年   17篇
  1986年   13篇
  1985年   14篇
  1984年   17篇
  1983年   6篇
  1982年   11篇
  1981年   12篇
  1980年   6篇
  1979年   10篇
  1978年   2篇
  1977年   2篇
  1976年   4篇
  1974年   2篇
排序方式: 共有6497条查询结果,搜索用时 0 毫秒
1.
2.
  1. Download : Download high-res image (123KB)
  2. Download : Download full-size image
  相似文献   
3.
4.
  1. Download : Download high-res image (261KB)
  2. Download : Download full-size image
  相似文献   
5.
《Current biology : CB》2020,30(24):4956-4972.e4
  1. Download : Download high-res image (111KB)
  2. Download : Download full-size image
  相似文献   
6.
The pathogens Vibrio cholerae and Haemophilus influenzae use tripartite ATP-independent periplasmic transporters (TRAPs) to scavenge sialic acid from host tissues. They use it as a nutrient or to evade the innate immune system by sialylating surface lipopolysaccharides. An essential component of TRAP transporters is a periplasmic substrate binding protein (SBP). Without substrate, the SBP has been proposed to rest in an open-state, which is not recognised by the transporter. Substrate binding induces a conformational change of the SBP and it is thought that this closed state is recognised by the transporter, triggering substrate translocation. Here we use real time single molecule FRET experiments and crystallography to investigate the open- to closed-state transition of VcSiaP, the SBP of the sialic acid TRAP transporter from V. cholerae. We show that the conformational switching of VcSiaP is strictly substrate induced, confirming an important aspect of the proposed transport mechanism. Two new crystal structures of VcSiaP provide insights into the closing mechanism. While the first structure contains the natural ligand, sialic acid, the second structure contains an artificial peptide in the sialic acid binding site. Together, the two structures suggest that the ligand itself stabilises the closed state and that SBP closure is triggered by physically bridging the gap between the two lobes of the SBP. Finally, we demonstrate that the affinity for the artificial peptide substrate can be substantially increased by varying its amino acid sequence and by this, serve as a starting point for the development of peptide-based inhibitors of TRAP transporters.  相似文献   
7.
8.
An algorithm is proposed for extracting regulatory signals from DNA sequences. The algorithm complexity is nearly quadratic. The results of testing the algorithm on artificial and natural sequences are presented.  相似文献   
9.
To effectively integrate DNA sequence analysis and classical nematode taxonomy, we must be able to obtain DNA sequences from formalin-fixed specimens. Microdissected sections of nematodes were removed from specimens fixed in formalin, using standard protocols and without destroying morphological features. The fixed sections provided sufficient template for multiple polymerase chain reaction-based DNA sequence analyses.  相似文献   
10.
Embryogenes is and hatching of eggs of Meloidogyne javanica were suppressed by brief heat treatment (46 C for 10 min). The period of suppression or arrested development differs according to the stage of development of the nematode when heat treatment is applied. The effect on hatching is much more pronounced than on embryogenesis.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号