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   292805篇
  免费   31870篇
  国内免费   264篇
  2016年   3385篇
  2015年   4846篇
  2014年   5392篇
  2013年   8069篇
  2012年   8823篇
  2011年   9013篇
  2010年   6006篇
  2009年   5494篇
  2008年   8158篇
  2007年   8293篇
  2006年   7824篇
  2005年   7635篇
  2004年   7479篇
  2003年   7224篇
  2002年   7035篇
  2001年   12111篇
  2000年   12120篇
  1999年   9668篇
  1998年   3621篇
  1997年   3796篇
  1996年   3704篇
  1995年   3287篇
  1994年   3261篇
  1993年   3298篇
  1992年   8108篇
  1991年   8092篇
  1990年   7735篇
  1989年   7718篇
  1988年   7088篇
  1987年   6793篇
  1986年   6208篇
  1985年   6384篇
  1984年   5307篇
  1983年   4492篇
  1982年   3528篇
  1981年   3317篇
  1980年   3084篇
  1979年   5134篇
  1978年   3971篇
  1977年   3873篇
  1976年   3553篇
  1975年   3914篇
  1974年   4336篇
  1973年   4265篇
  1972年   3798篇
  1971年   3556篇
  1970年   3227篇
  1969年   3137篇
  1968年   2846篇
  1967年   2466篇
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
111.
On the basis of their own data and the literature the authors have analyzed the mechanism of biological action of low-level radiation on cells. In studying the harmful effect of gamma-radiation (10-40 cGy) on HeLa cells it was shown that damages occurred in 12 postirradiation generations. Analysis of cell distribution within the colonies has demonstrated that the share of colonies with low cell content and the number of giant cell increase. These data indicate that low-level radiation causes reproductive cell death that can occur not immediately but in later generations.  相似文献   
112.
113.
Peak area matching and linear regression were used to quantify eight chlorinated pesticides and polychlorinated biphenyls (as Aroclor 1260) in human serum. There are no statistically significant differences in data obtained by these two quantifying techniques which were indicated by the paired t-test. For chlorinated pesticides, p = 0.053-0.62, and for polychlorinated biphenyls (as Aroclor 1260), p = 0.64. Analyte residues for the chlorinated pesticides ranged from 0.5 ppb for hexachlorobenzene (HCB) to 186 ppb for dichlorodiphenyldichloroethylene (DDE). Analyte residues for the polychlorinated biphenyls (as Aroclor 1260) ranged from 5-114 ppb. The absolute mean percent difference between the two quantifying techniques ranged from 0.06% for DDE to 8.06% for dieldrin (HEOD) among the chlorinated pesticides. The absolute mean percent difference between the two quantifying techniques for the polychlorinated biphenyls (as Aroclor 1260) was 3.4%. Peak area matching and linear regression were found to be comparable for quantifying these environmental residues in serum when the following conditions apply: 1) the concentration of the chlorinated pesticides is greater than or equal to 0.5 ppb (e.g., HCB, hexachlorocyclohexane (HCCH), oxychlordane (OC), heptachlor epoxide (HE), transnonachlor (TN), HEOD, and dichlorodiphenyltrichloroethane (DDT); 2) the concentration of the chlorinated pesticide is greater than or equal to 3 ppb (e.g., DDE); and 3) the total concentration of polychlorinated biphenyls (e.g., as Aroclor 1260) is greater than or equal to 5 ppb.  相似文献   
114.
115.
116.
117.
118.
119.
120.
In experiments on CBA mice it was shown that migration of 51Cr-labeled spleen lymphocytes, injected intravenously, to lymph nodes of intact recipients was suppressed 6-24 months after the administration of a radiopharmaceutic preparation of selenium-75-selenomethionine in a quantity forming the doses of 1 Gy and 1.5 Gy absorbed within the whole body and lymphoid organs, respectively. Migration of labeled lymphocytes to the liver, kidneys and lungs, as well as their retention in the circulating blood, were increased. As the result of the migration disorders the specific affinity of lymphocytes for peripheral lymphoid tissue decreased.  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