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   37776篇
  免费   3388篇
  国内免费   19篇
  2023年   102篇
  2022年   222篇
  2021年   607篇
  2020年   368篇
  2019年   487篇
  2018年   614篇
  2017年   537篇
  2016年   963篇
  2015年   1613篇
  2014年   1751篇
  2013年   2143篇
  2012年   2917篇
  2011年   2972篇
  2010年   1835篇
  2009年   1717篇
  2008年   2437篇
  2007年   2502篇
  2006年   2336篇
  2005年   2174篇
  2004年   2154篇
  2003年   1998篇
  2002年   1927篇
  2001年   472篇
  2000年   340篇
  1999年   467篇
  1998年   498篇
  1997年   376篇
  1996年   334篇
  1995年   300篇
  1994年   265篇
  1993年   281篇
  1992年   279篇
  1991年   224篇
  1990年   200篇
  1989年   220篇
  1988年   201篇
  1987年   169篇
  1986年   154篇
  1985年   187篇
  1984年   200篇
  1983年   153篇
  1982年   159篇
  1981年   141篇
  1980年   122篇
  1979年   102篇
  1978年   98篇
  1977年   99篇
  1976年   66篇
  1975年   55篇
  1973年   76篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
41.
42.
43.
44.

Background  

NOL7 is a candidate tumor suppressor that localizes to a chromosomal region 6p23. This locus is frequently lost in a number of malignancies, and consistent loss of NOL7 through loss of heterozygosity and decreased mRNA and protein expression has been observed in tumors and cell lines. Reintroduction of NOL7 into cells resulted in significant suppression of in vivo tumor growth and modulation of the angiogenic phenotype. Further, NOL7 was observed to localize to the nucleus and nucleolus of cells. However, the mechanisms regulating its subcellular localization have not been elucidated.  相似文献   
45.
46.
A survey was done of Canadians who had been interned by the Japanese during World War II to assess the prevalence of latent infection with Strongyloides stercoralis in this group. Packages containing three mail-in kits and a questionnaire were sent to 992 men, 694 (70%) of whom responded. Larvae were found in the stool specimens of four of the respondents. Examination of stool specimens after formalin-ether concentration was the most successful method of detecting Strongyloides larvae. The Baermann concentration technique yielded negative results in all four men. Three of the four cases of strongyloidiasis were detected after sampling of three fecal specimens. In the fourth case additional specimens were requested on the basis of data derived from the questionnaire. The most frequently cited clinical manifestations were abdominal pain, weight loss, diarrhea and rashes.  相似文献   
47.
48.
49.
Comparative mapping studies of X-linked genes in mammals have provided insights into the evolution of the X chromosome. Many reptiles including the American alligator, Alligator mississippiensis, do not appear to possess heteromorphic sex chromosomes, and sex is determined by the incubation temperature of the egg during embryonic development. Mapping of homologues of mammalian X-linked genes in reptiles could lead to a greater understanding of the evolution of vertebrate sex chromosomes. One of the genes used in the mammalian mapping studies was ZFX, an X-linked copy of the human ZFY gene which was originally isolated as a candidate for the mammalian testis-determining factor (TDF). ZFX is X-linked in eutherians, but maps to two autosomal locations in marsupials and monotremes, close to other genes associated with the eutherian X. The alligator homologue of the ZFY/ZFX genes, Zfc, has been isolated and described previously. A detailed karyotype of A. mississippiensis is presented, together with chromosomal in situ hybridisation data localising the Zfc gene to chromosome 3. Further chromosomal mapping studies using eutherian X-linked genes may reveal conserved chromosomal regions in the alligator that have become part of the eutherian X chromosome during evolution.  相似文献   
50.
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