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   183570篇
  免费   14487篇
  国内免费   50篇
  198107篇
  2018年   1830篇
  2017年   1783篇
  2016年   2280篇
  2015年   2190篇
  2014年   3001篇
  2013年   4377篇
  2012年   4899篇
  2011年   5417篇
  2010年   3765篇
  2009年   3415篇
  2008年   4953篇
  2007年   5237篇
  2006年   4930篇
  2005年   4638篇
  2004年   4780篇
  2003年   4680篇
  2002年   4655篇
  2001年   8444篇
  2000年   8639篇
  1999年   6378篇
  1998年   2012篇
  1997年   2055篇
  1996年   1815篇
  1993年   1689篇
  1992年   5246篇
  1991年   5421篇
  1990年   5174篇
  1989年   5151篇
  1988年   4779篇
  1987年   4515篇
  1986年   4117篇
  1985年   4272篇
  1984年   3429篇
  1983年   2939篇
  1982年   1945篇
  1981年   1750篇
  1980年   1738篇
  1979年   3238篇
  1978年   2556篇
  1977年   2298篇
  1976年   2090篇
  1975年   2560篇
  1974年   2907篇
  1973年   2824篇
  1972年   2665篇
  1971年   2430篇
  1970年   2124篇
  1969年   2033篇
  1968年   1920篇
  1967年   1749篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
994.
995.
A selective uptake of ethanol by presenting its 5% solution as the only source of fluid was elaborated in rats for 2 months. It was found that lithium chloride injected intravenously in a dose of 35 mg/kg twice per 24 hours for 14 days depressed the ethanol preference causing a motivation inversion whose mechanism was associated with the changes in the activity of the hypothalamic centres of the neuroendocrine regulation. A possibility of lithium salts in the therapy of chronic alcoholism is discussed.  相似文献   
996.
The authors carried out serological typing of 98 Pseudomonas aeruginosa strains, isolated from patients of burn department of the Sklifosovsky First Aid Institute in January-July, 1974, and of 215 strains obtained from other sources; their sensitivity to 13 antibiotics was determined. Pseudomonas aeruginosa cultures isolated from the patients were typed with O-sera of 10 serological types. The presence of several hospital strains of Pseudomonas aeruginosa was found by means of serological typing; along with these there were revealed cultures of this causative agent sporadically appearing in the department. Sensitivity to some antibiotics could serve as an additional criterion for differentiation of Pseudomonas aeruginosa strains of the same serological type.  相似文献   
997.
Characterization of p29, an estrogen-receptor associated tumor marker   总被引:2,自引:0,他引:2  
Monoclonal antibody D5, raised against cytosolic human estrogen receptor (ER) reacts with p29, a receptor-associated cytoplasmic serine phosphoprotein which does not bind steroid, While p29 selectively binds GTP and to a lesser extent ATP, in vitro GTP binding does not result in p29 phosphorylation. Under ER activating conditions, p29 associates with cytosolic ER; GTP, ATP and sodium molybdate block formation of immunoprecipitable p29-ER complexes. Nucleotide binding data suggest a role for p29 in the estrogen response machinery, possibly at the level of phosphate or nucleotide metabolism.  相似文献   
998.
999.
1000.
1. The renal cell lines, JTC-12 and MDCK, not only synthesize galactosylceramide 3-sulfate and lactosylceramide 3'-sulfate in vivo, but also contain enzymes that catalyze the transfer of sulfate to galactosylceramide and lactosylceramide in vitro. 2. Concentration of cations necessary for maximum sulfotransferase activity occurred at 40 mM Ca2+ with galactosylceramide and 15 mM Ca2+ with lactosylceramide as the substrate. Na+ was also found to stimulate the sulfation of galactosylceramide, but was slightly inhibitory for the sulfation of lactosylceramide. 3. The products of the in vitro assay mixture were characterized as galactosylceramide 3-sulfate and lactosylceramide 3'-sulfate by a variety of TLC separations. 4. The apparent Km of JTC-12 cells for galactosylceramide was 17 microM, while that for lactosylceramide was 82 microM. The Km values of MDCK cells were comparable to those of JTC-12 cells. Competition studies suggested that galactosylceramide and lactosylceramide were sulfated by a single enzyme in both cell lines.  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