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   115804篇
  免费   13847篇
  国内免费   1040篇
  130691篇
  2021年   1012篇
  2019年   902篇
  2018年   1239篇
  2017年   1161篇
  2016年   1506篇
  2015年   1895篇
  2014年   2321篇
  2013年   2872篇
  2012年   3373篇
  2011年   3257篇
  2010年   2183篇
  2009年   2120篇
  2008年   2632篇
  2007年   2627篇
  2006年   2569篇
  2005年   2336篇
  2004年   2264篇
  2003年   2318篇
  2002年   2227篇
  2001年   9759篇
  2000年   9594篇
  1999年   7274篇
  1998年   1699篇
  1997年   1833篇
  1996年   1617篇
  1995年   1425篇
  1994年   1324篇
  1993年   1260篇
  1992年   4817篇
  1991年   4538篇
  1990年   4020篇
  1989年   4033篇
  1988年   3615篇
  1987年   3092篇
  1986年   2780篇
  1985年   2681篇
  1984年   1979篇
  1983年   1732篇
  1982年   1232篇
  1981年   985篇
  1980年   915篇
  1979年   1764篇
  1978年   1361篇
  1977年   1199篇
  1976年   1028篇
  1975年   1150篇
  1974年   1167篇
  1973年   1164篇
  1972年   1038篇
  1971年   955篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
Restriction of apical growth in Phaseolus by enclosing the upperpart of the shoot in sealed or ventilated tubes induced developmentof axillary buds beneath the enclosure. Enclosed parts of shootsshowed a reduction of leaf growth and, in experiments wherethe tubes were sealed, of internode extension. Enclosure ofthe shoots in large vessels that did not restrict leaf expansion,but which contained 0?5 vols 10–6 ethylene, similarlyinduced axillary bud growth. Analysis of the gaseous extractof physically restricted shoots showed a 2?5-fold increase inethylene concentration. The results suggest involvement of ethylenein the release of correlative inhibition brought about by physicalrestriction of apical growth.  相似文献   
972.
The slow equilibration of the denatured state after rapid unfolding of a globular protein is examined by the cluster model of protein folding (Kanehisa &; Tsong, 1978). The detection of this process in ribonuclease A and its acid catalysis have been considered evidence for the proline isomerization model. Our calculation shows that similar kinetic behavior is also expected for the cluster model.  相似文献   
973.
The crystal structure of the complex of subtilisin BPN′ (EC 3.4.21.14) with its protein inhibitor (Streptomyces subtilisin inhibitor) was solved at 4.3 Å resolution, thus establishing the following. (1) Two subtilisin BPN′ molecules (2E) associate with one dimeric inhibitor molecule (I2) to form the complex molecule E2I2. (2) The conformation of neither the inhibitor nor subtilisin BPN′ undergoes any detectable change at this resolution upon complex formation. (3) The inhibitor binds to subtilisin to form an antiparallel β-sheet, as in the case of trypsin/ trypsin inhibitor complexes. (4) The scissible bond of the inhibitor is between Met73′ and Val74′, as proposed earlier (Ikenaka et al., 1974). (5) The protein inhibitor and the substrates bind to subtilisin BPN′ in essentially the same way.  相似文献   
974.
975.
976.
977.
O Suzuki  Y Katsumata  M Oya 《Life sciences》1979,24(24):2227-2230
1,4-Methylhistamine was characterized as substrate for monoamine oxidase (MAO) in rat liver mitochondria. The Km and Vmax values were 38.8 μM and 6.33 nmoles/mg protein/60 min, respectively. The inhibition experiments with clorgyline and deprenyl, the selective inhibitors for type A and type B MAO, showed that 1,4-methylhistamine was specific for type B MAO.  相似文献   
978.
Chen CY  Ikuma H 《Plant physiology》1979,63(4):704-708
The physiological nature of photoinduced germination of Onoclea sensibilis L. spores was investigated by temporarily applying a range of temperatures, particularly 40 C, before and after short light treatment. Controls were germinated at 25 C.  相似文献   
979.
Rate of skin blood flow in various regions of the body.   总被引:1,自引:0,他引:1  
Skin blood flow was measured by local clearance of 133Xe, and skin temperature was measured by medical thermography in various parts of the body. 1. A significant linear decrease in skin blood flow was observed with increasing age in the deltoid region. 2. The skin blood flow in the facial and pectoral areas was considerably higher than in the deltoid region. 3. The skin blood flow in the posterior cervical, lateral thoracic, lateral abdominal, and gluteal sites was less than in the deltoid region.  相似文献   
980.
In vitro transcription of a cloned mouse ribosomal RNA gene   总被引:24,自引:13,他引:11       下载免费PDF全文
  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