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   7353篇
  免费   704篇
  国内免费   6篇
  2021年   84篇
  2020年   54篇
  2019年   58篇
  2018年   87篇
  2017年   80篇
  2016年   118篇
  2015年   206篇
  2014年   199篇
  2013年   308篇
  2012年   341篇
  2011年   355篇
  2010年   194篇
  2009年   205篇
  2008年   311篇
  2007年   311篇
  2006年   294篇
  2005年   309篇
  2004年   298篇
  2003年   322篇
  2002年   306篇
  2001年   97篇
  2000年   78篇
  1999年   83篇
  1998年   89篇
  1997年   61篇
  1996年   73篇
  1995年   67篇
  1994年   60篇
  1993年   58篇
  1992年   68篇
  1991年   67篇
  1990年   63篇
  1989年   75篇
  1988年   56篇
  1987年   73篇
  1986年   59篇
  1985年   62篇
  1984年   74篇
  1983年   79篇
  1982年   87篇
  1981年   88篇
  1980年   86篇
  1979年   63篇
  1978年   62篇
  1977年   74篇
  1976年   80篇
  1975年   62篇
  1974年   66篇
  1973年   61篇
  1970年   53篇
排序方式: 共有8063条查询结果,搜索用时 15 毫秒
991.
Fifty-one Bifidobacterium strains were isolated from the feces of healthy adults (30–40 years old) and seniors (older than 70 years of age). B. adolescentis, B. breve, B. infantis, and B. longum were isolated from the healthy adults and B. adolescentis and B. longum from elderly subjects. The tested bacteria bound, in vitro, to intestinal mucus in a strain dependent manner. The strains isolated from healthy adults, and especially B. adolescentis, bound better to intestinal mucus than those isolated from seniors. These results indicate that the mucosal adhesive properties of the human Bifidobacterium flora were reduced with the aging of the host. This shift to a Bifidobacterium flora with reduced adhesive abilities may explain the decrease in bifidobacteria levels in the intestinal microflora of aging people. Received: 7 February 2001 / Accepted: 3 April 2001  相似文献   
992.
993.
A swine resource family was constructed at the National Institute of Animal Industry, Japan, in order to determine the genetic regions responsible for economically important traits, including fetus development. To identify genes expressed in the early stage of embryo development, we cataloged and mapped genes expressed in a 28-day-old normal pig embryo. In this effort, we have mapped 64 genes, which have map information in human genome onto a swine radiation hybrid (RH) map, IMpRH. These mappings provided additional chromosomal homologies between swine and human to improve the comparative map between the two species. The distribution of the genes assigned to swine chromosomes are as follows: 9 genes were assigned on SSC6; 6 genes each assigned on SSC5 and SSC14; 5 genes each assigned on SSC3, SSC4, and SSC8; 4 genes each assigned on SSC1, SSC7, SSC9, and SSC15; 3 genes each assigned on SSC2, SSC13 and SSCX; and 1 gene each assigned on SSC10, SSC11, and SSC16. Moreover, the present findings revealed 18 new chromosomal homologies between pig and human. Briefly, SSC3 regions were indicated to correspond with HSA1 and HSA10; SSC4 with HSA6; SSC5 with HSA2, HSA15, and HSA16; SSC6 with HSA3, HSA6, and HSA20; SSC7 with HSA11; SSC8 with HSA3, HSA6, and HSA7; SSC9 with HSA8; SSC13 with HSA1; SSC14 with HSA13; SSC15 with HSA19; SSC16 with HSA9. Received: 19 December 2000 / Accepted: 13 March 2001  相似文献   
994.
Lead poisoning was produced in suckling rats by lead fed to lactating mother rats being transmitted to newborns via maternal milk. The brain of 25 day old lead poisoned rats contained 6.0 to 12.5 ppm lead. Zinc was depressed 56% (cerebral cortex), 45% in cerebellum and 43% (caudate nucleus) whereas copper was depressed 52% in the cerebellum. Inhibition of monoamine oxidase (pargyline) or partial depletion of serotonin and norepinephrine did not alter the concentration of Fe, Cu, Zn, or Mn in brain.  相似文献   
995.
996.
997.
Summary A procedure is described for large-scale isolation of micromeres from 16-cell stage sea urchin embryos. One to two grams of >99% pure, viable micromeres (2.3 to 4.6 × 108 cells) are routinely isolated in a single preparation. In culture, these cells uniformly proceed through their normal development, in synchrony with micromeres in whole embryos, ultimately differentiating typical larval skeletal structures. The attributes of this procedure are: (a) the very early time of isolation of the cells, directly after the division that establishes the cell line; (b) the large yield of cells; (c) the purity of the preparation of cell; and (d) their synchronous development in culture through skeletogenesis. The procedure greatly aids in making sea urchin micromeres a favorable material for molecular analysis of development. This work was supported in part by the following grants from the National Institutes of Health: Grant HL-10312 to A.H.W., Grant GM-20784 to Helen R. Whiteley, Grant ES-02190 to N. Karle Mottet, M.D., and Training Grants ES-07032 and HD-00266.  相似文献   
998.
999.
1000.
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