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   55267篇
  免费   3983篇
  国内免费   137篇
  59387篇
  2021年   383篇
  2020年   327篇
  2019年   368篇
  2018年   879篇
  2017年   844篇
  2016年   1303篇
  2015年   1956篇
  2014年   2130篇
  2013年   2741篇
  2012年   3366篇
  2011年   3156篇
  2010年   1969篇
  2009年   1494篇
  2008年   2631篇
  2007年   2615篇
  2006年   2565篇
  2005年   2403篇
  2004年   2369篇
  2003年   2182篇
  2002年   2190篇
  2001年   1600篇
  2000年   1707篇
  1999年   1351篇
  1998年   527篇
  1997年   426篇
  1996年   401篇
  1995年   376篇
  1994年   401篇
  1993年   359篇
  1992年   825篇
  1991年   823篇
  1990年   782篇
  1989年   734篇
  1988年   675篇
  1987年   608篇
  1986年   595篇
  1985年   568篇
  1984年   502篇
  1983年   464篇
  1982年   409篇
  1981年   396篇
  1979年   512篇
  1978年   375篇
  1977年   336篇
  1975年   385篇
  1974年   374篇
  1973年   341篇
  1972年   368篇
  1971年   332篇
  1968年   319篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
In 1990 and 1994, two males of Golden Eagles were found with small lead particles in their stomachs. Both individuals died soon after they had been taken sitting on the soil in bad condition. There are some findings of dead eagles in the same area which showed no sign of having been injured. The two cases of presumed lead poisoning coincide with intense efforts to reduce the number of ChamoixRupicapra rupicapra by hunting. The bullets used contain a nucleus of lead and eagles were seen taking the entrails of the shot chamoix.  相似文献   
4.
5.
The recent identification of VKORC1 has made important contributions to our understanding of the vitamin K cycle. The VKORC1 enzyme was shown to be the molecular target of coumarin drugs. Mutations and polymorphisms in coding and noncoding regions of the VKORC1 gene have been shown to cause both a partial to total coumarin resistance and coumarin sensitivity. Availability of molecular diagnostics (VKORC1, CYP2C9) and drug monitoring by HCPLC (determination of coumarin, vitamin K, and vitamin K epoxide levels) is helpful for detecting hereditary and acquired factors influencing coumarin therapy. In the future, these tools may be instrumental in designing individualized oral anticoagulation therapy regimens.  相似文献   
6.
ANP (atrial natriuretic peptide), a peptide found in granules of mammalian atrial cardiac myocytes, has been shown to be active in regulation of blood pressure and body water homeostasis. The existence of ANP in atrium, pituitary, adrenal gland, and kidney of the rat had been immunocytochemically demonstrated with an antibody against rat ANP (102-126). We used the same antibody in immunocytochemical studies for the detection of ANP in peripheral organs of the tree shrew (Tupaia belangeri). The antibody stained granules in myocytes of cardiac atria which indicated that it reacted with tree shrew ANP. In contrast to the rat, no immunoreactive cells were found in pituitaries and adrenal glands. However, in the kidneys distal tubules in outer medulla and cortex were labeled. Ascending limbs of distal tubules were intensely stained when either the peroxidase-antiperoxidase (PAP) or the indirect immunofluorescence method were used. Collecting ducts and convoluted distal tubules in the outer cortex showed a granular type of staining when the immunofluorescence method was used. These data indicate that ANP is present in epithelial cells of distal tubules and collecting ducts, where it may be involved in the regulation of renal salt excretion.  相似文献   
7.
8.
9.
10.
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