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   7808篇
  免费   36篇
  国内免费   24篇
系统科学   57篇
丛书文集   18篇
教育与普及   4篇
理论与方法论   57篇
现状及发展   3864篇
研究方法   461篇
综合类   3320篇
自然研究   87篇
  2018年   57篇
  2017年   55篇
  2016年   62篇
  2014年   50篇
  2013年   90篇
  2012年   200篇
  2011年   275篇
  2010年   87篇
  2008年   180篇
  2007年   192篇
  2006年   194篇
  2005年   197篇
  2004年   208篇
  2003年   156篇
  2002年   160篇
  2001年   224篇
  2000年   179篇
  1999年   148篇
  1992年   132篇
  1991年   90篇
  1990年   101篇
  1989年   80篇
  1988年   82篇
  1987年   108篇
  1986年   74篇
  1985年   123篇
  1984年   115篇
  1983年   89篇
  1982年   86篇
  1981年   72篇
  1980年   96篇
  1979年   249篇
  1978年   205篇
  1977年   196篇
  1976年   135篇
  1975年   157篇
  1974年   240篇
  1973年   199篇
  1972年   218篇
  1971年   220篇
  1970年   284篇
  1969年   237篇
  1968年   212篇
  1967年   212篇
  1966年   212篇
  1965年   160篇
  1964年   57篇
  1958年   76篇
  1957年   52篇
  1954年   52篇
排序方式: 共有7868条查询结果,搜索用时 220 毫秒
891.
Summary Female rats fed 0, 25, 2500 and 10,000 IU vitamin E/kg diet for 3 months were examined for reproductive performance. On 10,000 IU vitamin E/kg diet, the fertility of inseminated rats was significantly reduced as compared to rats given normal or nutritional levels of vitamin E.This work was supported by research grants from the National Research Council of Canada and the Research Committee of The University of British Columbia. We thank Mrs Virginia Green for her help in statistical analysis. Reprint requests should be addressed to Dr I. D. Desai, Professor of Nutrition.  相似文献   
892.
893.
In contrary to the wild strain, a monocaryotic mutant of Coprinus cinereus (basidiomycete) does not contain hydrosoluble, complex-bound sterols. Under nystatine-treatment, however, the mutant is induced to produce this kind of stereols in abundance. Furthermore, nystatine highly increases sporulation of the mutant and decreases sporulation of the wild strain.  相似文献   
894.
Marine microvibrios, predators of E. coli, have been detected worldwide, from equatorial waters to the polar regions. The morphology and behavior of two microvibrios have been studied. Their multiplication and aggressiveness in regard to their bacterial prevy are not impeded by dialysis membranes and manifest themselves, away from all direct contact between the predator and its prey.  相似文献   
895.
896.
Mechanosensitivity of mammalian auditory hair cells in vitro   总被引:1,自引:0,他引:1  
I J Russell  G P Richardson  A R Cody 《Nature》1986,321(6069):517-519
Intracellular responses recorded in vitro from the cochleas of anaesthetized mammals have shown that the mechanoreceptive inner and outer hair cells are sharply tuned, accounting for many of the properties of the afferent fibres in the auditory nerve. However, in vivo it has not been possible to measure directly the excitatory mechanical input to these cells (the displacement of their mechanosensitive stereocilia) and thus to determine the relationship between the receptor potentials and displacement of their stereocilia. As a means of circumventing this technical difficulty, we have developed an organ culture of the mouse cochlea and here we describe the receptor potentials generated by the hair cells in response to direct displacement of their stereocilia.  相似文献   
897.
Summary When guinea pigs instead of rabbits were used as the host animals, 8–16 times higher antibody titers against human lung elastin peptides were produced with only 1/20 the amount of antigen per unit body weight. This corresponds to a 200-fold enhancement of the immune response.Presented at the 6th Colloquium of the Federation of European Connective Tissue Clubs, Paris, August 28–30, 1978. The data form part of the Ph.D. thesis submitted by T.V. Darnule to the Department of Biology, New York University. Supported in part by NIH Program Project Grant HL15832 and by a Parker B. Francis Fellowship to T.V. Darnule.  相似文献   
898.
    
Summary By repeated administration of tetrachloromethane, cirrhosis of the liver was evoked in dogs. In the course of the experiment one bitch had five litters, in all of which lesions of hepatic cells were found. In one group of animals, a diffuse steatosis of the liver was present; in the other group zonal necrosis was found. Malformations or fibrotic changes were not observed.  相似文献   
899.
900.
GARVIE EI  CHEESEMAN GC 《Nature》1958,181(4622):1540-1541
  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