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   97796篇
  免费   7755篇
  国内免费   32篇
  2021年   860篇
  2018年   1311篇
  2017年   1225篇
  2016年   1659篇
  2015年   1764篇
  2014年   2122篇
  2013年   3006篇
  2012年   3287篇
  2011年   3388篇
  2010年   2513篇
  2009年   2124篇
  2008年   3083篇
  2007年   3030篇
  2006年   2847篇
  2005年   2677篇
  2004年   2678篇
  2003年   2574篇
  2002年   2380篇
  2001年   4413篇
  2000年   4164篇
  1999年   3238篇
  1998年   1048篇
  1997年   1041篇
  1996年   927篇
  1995年   845篇
  1994年   834篇
  1992年   2461篇
  1991年   2467篇
  1990年   2472篇
  1989年   2219篇
  1988年   2076篇
  1987年   1989篇
  1986年   1843篇
  1985年   1841篇
  1984年   1508篇
  1983年   1302篇
  1982年   936篇
  1981年   880篇
  1979年   1438篇
  1978年   1131篇
  1977年   1015篇
  1976年   973篇
  1975年   1156篇
  1974年   1257篇
  1973年   1340篇
  1972年   1185篇
  1971年   1042篇
  1970年   925篇
  1969年   954篇
  1968年   834篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
The effect of low-frequency magnetic field (MF) on systemic blood pressure has been studied in chronic experiments on 21 spontaneously hypertensive rats. The animals' kidney area was exposed to MF (induction value 30T). Direct blood pressure measurements have revealed an antihypertensive effect.  相似文献   
82.
The recognition of influenza virus hemagglutinin (HA) by T lymphocytes was examined by assaying the T cell proliferative response of influenza virus-primed T cells to purified HA of different influenza A subtypes or to isolated heavy (HA1) or light (HA2) polypeptide chains of the HA molecule. The proliferative response to HA was dependent on the activation of an Ly-1+2- subset of T cells and required the presence of nylon wool-adherent, radiation-resistant accessory cells. T cells from mice primed by infection with one strain of type A influenza virus cross-reacted with other purified HA not only of the same subtype as the priming virus but also of serologically distinct subtypes of influenza A (but not B) virus. The response of virus-primed T cells to the homologous HA or to HA of the same subtype was shown to involve recognition of determinants on both the HA1 and the HA2 chains. The recognition of HA of different subtype by cross-reactive T cells appeared to be directed predominantly to determinants on HA2. Because the antibody response to influenza virus HA is not cross-reactive between subtypes and is directed predominantly to determinants on HA1, the present results indicate that at least some of the determinants on HA recognized by T cells are different from those recognized by B cells and that the HA2 chain may be involved primarily in stimulation of T cell rather than B cell immunity.  相似文献   
83.
84.
85.
86.
Journal of Evolutionary Biochemistry and Physiology - Changes in bioelectrical impedance of the myocardium and liver were revealed in male Wistar rats chronically exposed to doxorubicin....  相似文献   
87.
88.
Targeting of many transmembrane proteins to post-Golgi compartments is dependent on cytoplasmically exposed sorting signals. The most widely used signals conform to the tyrosine- or the leucine-based motifs. Both types of signals have been implicated in protein localization to the same intracellular compartments, but previous results from both cell-free experiments and studies of transfected cell lines have indicated that the two types of signals interact with separate components of the sorting machinery. We have overexpressed several transmembrane proteins in stably transfected Madin-Darby canine kidney cells using an inducible promoter system. Overexpression of proteins containing tyrosine- or leucine-based sorting signals resulted in reduced internalization of the transferrin receptor, whereas recycling and polarized distribution was not influenced. Our results indicate that proteins with tyrosine- and leucine-based sorting signals can be transported along common saturable pathways.  相似文献   
89.
90.
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