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   2207篇
  免费   11篇
  国内免费   33篇
系统科学   51篇
丛书文集   14篇
教育与普及   3篇
理论与方法论   45篇
现状及发展   900篇
研究方法   202篇
综合类   975篇
自然研究   61篇
  2019年   13篇
  2018年   21篇
  2017年   21篇
  2016年   21篇
  2015年   17篇
  2014年   18篇
  2013年   42篇
  2012年   84篇
  2011年   116篇
  2010年   28篇
  2009年   12篇
  2008年   66篇
  2007年   62篇
  2006年   79篇
  2005年   72篇
  2004年   89篇
  2003年   105篇
  2002年   134篇
  2001年   150篇
  2000年   106篇
  1999年   70篇
  1997年   12篇
  1992年   28篇
  1990年   21篇
  1989年   14篇
  1988年   25篇
  1987年   27篇
  1986年   25篇
  1985年   21篇
  1984年   25篇
  1983年   19篇
  1982年   14篇
  1981年   17篇
  1980年   24篇
  1979年   43篇
  1978年   38篇
  1977年   34篇
  1976年   33篇
  1975年   41篇
  1974年   30篇
  1973年   34篇
  1972年   49篇
  1971年   46篇
  1970年   32篇
  1969年   36篇
  1968年   26篇
  1967年   31篇
  1966年   35篇
  1965年   22篇
  1958年   9篇
排序方式: 共有2251条查询结果,搜索用时 31 毫秒
91.
Genome-wide association (GWA) studies have identified multiple loci at which common variants modestly but reproducibly influence risk of type 2 diabetes (T2D). Established associations to common and rare variants explain only a small proportion of the heritability of T2D. As previously published analyses had limited power to identify variants with modest effects, we carried out meta-analysis of three T2D GWA scans comprising 10,128 individuals of European descent and approximately 2.2 million SNPs (directly genotyped and imputed), followed by replication testing in an independent sample with an effective sample size of up to 53,975. We detected at least six previously unknown loci with robust evidence for association, including the JAZF1 (P = 5.0 x 10(-14)), CDC123-CAMK1D (P = 1.2 x 10(-10)), TSPAN8-LGR5 (P = 1.1 x 10(-9)), THADA (P = 1.1 x 10(-9)), ADAMTS9 (P = 1.2 x 10(-8)) and NOTCH2 (P = 4.1 x 10(-8)) gene regions. Our results illustrate the value of large discovery and follow-up samples for gaining further insights into the inherited basis of T2D.  相似文献   
92.
We identified a SNP in the DPP6 gene that is consistently strongly associated with susceptibility to amyotrophic lateral sclerosis (ALS) in different populations of European ancestry, with an overall P value of 5.04 x 10(-8) in 1,767 cases and 1,916 healthy controls and with an odds ratio of 1.30 (95% confidence interval (CI) of 1.18-1.43). Our finding is the first report of a genome-wide significant association with sporadic ALS and may be a target for future functional studies.  相似文献   
93.
94.
95.
96.
97.
98.
New use of BCG for recombinant vaccines   总被引:147,自引:0,他引:147  
BCG, a live attenuated tubercle bacillus, is the most widely used vaccine in the world and is also a useful vaccine vehicle for delivering protective antigens of multiple pathogens. Extrachromosomal and integrative expression vectors carrying the regulatory sequences for major BCG heat-shock proteins have been developed to allow expression of foreign antigens in BCG. These recombinant BCG strains can elicit long-lasting humoral and cellular immune responses to foreign antigens in mice.  相似文献   
99.
T-cell differentiation in the thymus is thought to involve a progression from the CD4-CD8- phenotype through CD4+CD8+ intermediates to mature CD4+ or CD8+ cells. There is evidence that during this process T cells bearing receptors potentially reactive to 'self' are deleted by a process termed 'negative selection' One example of this process occurs in mice carrying polymorphic Mls antigens, against which a detectable proportion of T cells are autoreactive. These mice show clonal deletion of thymic and peripheral T-cell subsets that express the autoreactive V beta 3 segment of the T-cell antigen receptor, but at most a two-fold depletion of thymic cells at the CD4+CD8+ stage. By contrast, transgenic mice bearing both alpha and beta chain genes encoding autoreactive receptors recognizing other ligands, show severe depletion of CD4+CD8+ thymocytes as well, suggesting that negative selection occurs much earlier. We report here the Mls 2a/3a mediated elimination of T cells expressing a transgene encoded V beta 3-segment, in T-cell receptor alpha/beta and beta-transgenic mice. Severe depletion of CD4+CD8+ thymocytes is seen only in the alpha/beta chain transgenic mice, whereas both strains delete mature V beta 3 bearing CD4+ and CD8+ T cells efficiently. We conclude that severe CD4+CD8+ thymocyte deletion in alpha/beta transgenic mice results from the premature expression of both receptor chains, and does not reflect a difference in the timing or mechanism of negative selection for Mls antigens as against the allo- and MHC class 1-restricted antigens used in the other studies.  相似文献   
100.
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