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   93458篇
  免费   2187篇
  国内免费   46篇
  95691篇
  2018年   1127篇
  2017年   1274篇
  2016年   3042篇
  2015年   6321篇
  2014年   6023篇
  2013年   5891篇
  2012年   4982篇
  2011年   2349篇
  2010年   2280篇
  2009年   2173篇
  2008年   824篇
  2007年   797篇
  2006年   856篇
  2005年   6925篇
  2004年   5560篇
  2003年   3823篇
  2002年   1348篇
  2001年   1343篇
  2000年   539篇
  1999年   1614篇
  1998年   404篇
  1997年   196篇
  1992年   2079篇
  1991年   2161篇
  1990年   2184篇
  1989年   2149篇
  1988年   2109篇
  1987年   1979篇
  1986年   1772篇
  1985年   1833篇
  1984年   1230篇
  1983年   964篇
  1982年   521篇
  1981年   484篇
  1980年   438篇
  1979年   1258篇
  1978年   885篇
  1977年   729篇
  1976年   752篇
  1975年   1024篇
  1974年   1238篇
  1973年   1252篇
  1972年   1183篇
  1971年   1154篇
  1970年   1056篇
  1969年   1066篇
  1968年   915篇
  1967年   922篇
  1966年   745篇
  1965年   547篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
The present study has shown that on the level of the parasitic system the epidemic process is a biological system, wherein the host population serves as the internal regulator, the mechanism of transmission serves as the external regulator and the parasite population, as the regulated object. The biological regulating mechanisms of the epidemic process have fundamental differences in the groups of infectious with various mechanisms of transmission, and the specific nature of the mechanism of transmission determines the peculiar features of the biological mechanism which governs the self-regulation of the epidemic process. In contrast, on a higher level of the organization of the epidemic process, i. e. on the level of the socio-ecological system, the epidemic process is a biosocial system, wherein the human society serves as the regulator, the parasitic system serves as the regulated object and the mechanism of transmission plays the role of the filter which determines the scope of social factors, most important in the regulation of the epidemic process in a given infection. The spontaneous regulation of the epidemic process is the freed forward channel from the regulator to the regulated object, and the controlled regulation is the feedback channel.  相似文献   
72.
73.
74.
Protoplasts of Schizosaccharomyces pombe, grown on a rich nutrient medium, were treated with a peptide factor isolated from cultures of the protozoan Tetrahymena pyriformis. The peptide factor is known to inhibit RNA synthesis in Tetrahymena. It has now been shown that the peptide factor also inhibits RNA synthesis in yeast protoplasts without affecting protein synthesis.  相似文献   
75.
76.
77.
78.
The cytotoxic and radiosensitizing effects of hyperthermia was shown on Ehrlich ascites tumor cells heated in vitro. The effect of hyperthermia resulted in the formation of local lesions in membranes of dying cells.  相似文献   
79.
By using the yeast two-hybrid system we identified a novel protein from the human brain interacting with the C terminus of somatostatin receptor subtype 2. This protein termed somatostatin receptor interacting protein is characterized by a novel domain structure, consisting of six N-terminal ankyrin repeats followed by SH3 and PDZ domains, several proline-rich regions, and a C-terminal sterile alpha motif. It consists of 2185 amino acid residues encoded by a 9-kilobase pair mRNA; several splice variants have been detected in human and rat cDNA libraries. Sequence comparison suggests that the novel multidomain protein, together with cortactin-binding protein, forms a family of cytoskeletal anchoring proteins. Fractionation of rat brain membranes indicated that somatostatin receptor interacting protein is enriched in the postsynaptic density fraction. The interaction of somatostatin receptor subtype 2 with its interacting protein was verified by overlay assays and coimmunoprecipitation experiments from transfected human embryonic kidney cells. Somatostatin receptor subtype 2 and the interacting protein display a striking overlap of their expression patterns in the rat brain. Interestingly, in the hippocampus the mRNA for somatostatin receptor interacting protein was not confined to the cell bodies but was also observed in the molecular layer, suggesting a dendritic localization of this mRNA.  相似文献   
80.
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