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   1483篇
  免费   7篇
  国内免费   16篇
系统科学   10篇
丛书文集   4篇
教育与普及   31篇
理论与方法论   1篇
现状及发展   656篇
研究方法   78篇
综合类   699篇
自然研究   27篇
  2018年   25篇
  2017年   19篇
  2015年   9篇
  2012年   25篇
  2011年   34篇
  2010年   10篇
  2009年   37篇
  2008年   35篇
  2007年   54篇
  2006年   25篇
  2005年   27篇
  2004年   58篇
  2003年   29篇
  2002年   33篇
  2001年   82篇
  2000年   59篇
  1999年   71篇
  1992年   31篇
  1991年   20篇
  1990年   16篇
  1989年   15篇
  1988年   23篇
  1987年   11篇
  1986年   13篇
  1985年   25篇
  1984年   15篇
  1983年   11篇
  1982年   11篇
  1980年   18篇
  1979年   31篇
  1978年   23篇
  1977年   21篇
  1976年   24篇
  1975年   35篇
  1974年   23篇
  1973年   34篇
  1972年   22篇
  1971年   46篇
  1970年   39篇
  1969年   36篇
  1968年   41篇
  1967年   36篇
  1966年   34篇
  1965年   22篇
  1964年   16篇
  1960年   9篇
  1959年   14篇
  1958年   24篇
  1957年   22篇
  1956年   13篇
排序方式: 共有1506条查询结果,搜索用时 31 毫秒
21.
We performed a genome-wide association study of melanoma in a discovery cohort of 2,168 Australian individuals with melanoma and 4,387 control individuals. In this discovery phase, we confirm several previously characterized melanoma-associated loci at MC1R, ASIP and MTAP-CDKN2A. We selected variants at nine loci for replication in three independent case-control studies (Europe: 2,804 subjects with melanoma, 7,618 control subjects; United States 1: 1,804 subjects with melanoma, 1,026 control subjects; United States 2: 585 subjects with melanoma, 6,500 control subjects). The combined meta-analysis of all case-control studies identified a new susceptibility locus at 1q21.3 (rs7412746, P = 9.0 × 10(-11), OR in combined replication cohorts of 0.89 (95% CI 0.85-0.95)). We also show evidence suggesting that melanoma associates with 1q42.12 (rs3219090, P = 9.3 × 10(-8)). The associated variants at the 1q21.3 locus span a region with ten genes, and plausible candidate genes for melanoma susceptibility include ARNT and SETDB1. Variants at the 1q21.3 locus do not seem to be associated with human pigmentation or measures of nevus density.  相似文献   
22.
We report a genome-wide association study for open-angle glaucoma (OAG) blindness using a discovery cohort of 590 individuals with severe visual field loss (cases) and 3,956 controls. We identified associated loci at TMCO1 (rs4656461[G] odds ratio (OR) = 1.68, P = 6.1 × 10(-10)) and CDKN2B-AS1 (rs4977756[A] OR = 1.50, P = 4.7 × 10(-9)). We replicated these associations in an independent cohort of cases with advanced OAG (rs4656461 P = 0.010; rs4977756 P = 0.042) and two additional cohorts of less severe OAG (rs4656461 combined discovery and replication P = 6.00 × 10(-14), OR = 1.51, 95% CI 1.35-1.68; rs4977756 combined P = 1.35 × 10(-14), OR = 1.39, 95% CI 1.28-1.51). We show retinal expression of genes at both loci in human ocular tissues. We also show that CDKN2A and CDKN2B are upregulated in the retina of a rat model of glaucoma.  相似文献   
23.
We have developed technologies that simplify genomic library construction and screening, substantially reducing both the time and the cost associated with traditional library screening methods and facilitating the generation of gene-targeting constructs. By taking advantage of homologous recombination in Escherichia coli, we were able to use as little as 80 bp of total sequence homology to screen for a specific gene from a genomic library in plasmid or phage form. This method, called recombination cloning (REC), takes only a few days instead of the several weeks required for traditional plaque-lift methods. In addition, because every clone in the mouse genomic library we have constructed has a negative selection marker adjacent to the genomic insert, REC screening can generate gene-targeting vectors in one step, from library screening to finished construct. Conditional targeting constructs can be generated easily with minimal additional manipulation.  相似文献   
24.
25.
26.
27.
28.
29.
30.
Summary The isolation of patulin I and pyrenophorol II from submerse cultures ofByssochlamys nivea Westling is described.  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