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   41150篇
  免费   72篇
  国内免费   114篇
系统科学   211篇
丛书文集   854篇
教育与普及   108篇
理论与方法论   256篇
现状及发展   17993篇
研究方法   1634篇
综合类   19672篇
自然研究   608篇
  2013年   258篇
  2012年   570篇
  2011年   1213篇
  2010年   254篇
  2008年   744篇
  2007年   732篇
  2006年   769篇
  2005年   787篇
  2004年   737篇
  2003年   732篇
  2002年   729篇
  2001年   1181篇
  2000年   1086篇
  1999年   751篇
  1992年   714篇
  1991年   571篇
  1990年   610篇
  1989年   609篇
  1988年   605篇
  1987年   606篇
  1986年   613篇
  1985年   775篇
  1984年   630篇
  1983年   493篇
  1982年   455篇
  1981年   429篇
  1980年   550篇
  1979年   1237篇
  1978年   1053篇
  1977年   1035篇
  1976年   768篇
  1975年   850篇
  1974年   1184篇
  1973年   1054篇
  1972年   1092篇
  1971年   1312篇
  1970年   1685篇
  1969年   1318篇
  1968年   1272篇
  1967年   1290篇
  1966年   1110篇
  1965年   816篇
  1964年   221篇
  1959年   505篇
  1958年   765篇
  1957年   587篇
  1956年   508篇
  1955年   433篇
  1954年   500篇
  1948年   304篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
841.
842.
843.
844.
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   
845.
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   
846.
To identify renally expressed genes that influence risk for hypertension, we integrated expression quantitative trait locus (QTL) analysis of the kidney with genome-wide correlation analysis of renal expression profiles and blood pressure in recombinant inbred strains derived from the spontaneously hypertensive rat (SHR). This strategy, together with renal transplantation studies in SHR progenitor, transgenic and congenic strains, identified deficient renal expression of Cd36 encoding fatty acid translocase as a genetically determined risk factor for spontaneous hypertension.  相似文献   
847.
848.
This review discusses the state-of-the-art in molecular research on the most prominent and widely applied lantibiotic, i.e., nisin. The developments in understanding its complex biosynthesis and mode of action are highlighted. Moreover, novel applications arising from engineering either nisin itself, or from the construction of totally novel dehydrated and/or lanthionine-containing peptides with desired bioactivities are described. Several challenges still exist in understanding the immunity system and the unique multiple reactions occurring on a single substrate molecule, carried out by the dehydratase NisB and the cyclization enzyme NisC. The recent elucidation of the 3-D structure of NisC forms the exciting beginning of further 3-D-structure determinations of the other biosynthetic enzymes, transporters and immunity proteins. Advances in achieving in vitro activities of lanthionine-forming enzymes will greatly enhance our understanding of the molecular characteristics of the biosynthesis process, opening up new avenues for developing unique and novel biocatalytic processes. Received 9 April 2007; received after revision 31 August 2007; accepted 28 September 2007  相似文献   
849.
850.
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