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   513276篇
  免费   50179篇
  国内免费   181篇
  2018年   5518篇
  2017年   5266篇
  2016年   6906篇
  2015年   7954篇
  2014年   9965篇
  2013年   14305篇
  2012年   16242篇
  2011年   16903篇
  2010年   11645篇
  2009年   10263篇
  2008年   14884篇
  2007年   15565篇
  2006年   14690篇
  2005年   13974篇
  2004年   14149篇
  2003年   13650篇
  2002年   13464篇
  2001年   21939篇
  2000年   21734篇
  1999年   17249篇
  1998年   5852篇
  1997年   5803篇
  1996年   5517篇
  1995年   5246篇
  1994年   5178篇
  1993年   5011篇
  1992年   14334篇
  1991年   14130篇
  1990年   13959篇
  1989年   13737篇
  1988年   12799篇
  1987年   12156篇
  1986年   11019篇
  1985年   11314篇
  1984年   9244篇
  1983年   7945篇
  1982年   5964篇
  1981年   5199篇
  1980年   5018篇
  1979年   8987篇
  1978年   6847篇
  1977年   6321篇
  1976年   6006篇
  1975年   6733篇
  1974年   7424篇
  1973年   7426篇
  1972年   6757篇
  1971年   6321篇
  1970年   5389篇
  1969年   5244篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
1. Effects of growth hormone (GH) were examined on short-term aspects of seawater adaptation in coho salmon smolts. 2. Injection of somatostatin (SRIF) immediately prior to seawater entry suppressed plasma GH levels, but did not have any significant effects at 6 or 12 hr on hematocrits, plasma glucose or plasma Na+ levels. 3. Plasma GH levels increased 250% within 36 hr after seawater exposure. 4. Plasma glucose levels, in contrast, were significantly lower in the seawater fish after 36 hr post-exposure. 5. Plasma Na+ levels increased to 190 mEq/1 by 24 hr but subsequently returned to freshwater levels while hematocrits showed no significant changes over the 72 hr of exposure. 6. The significance of these results is discussed in terms of successful seawater adaptation in coho salmon.  相似文献   
992.
993.
The ability of serotonin derivatives to stimulate cAMP accumulation in isolated nerve terminals and lumbar enlargement of the spinal cord of normal rats was compared. The effect of the compounds on the intensity of spinal pain syndrome was also assessed. It has been established that substitutes injected into NH2-group of serotonin in 5-OH position attenuate the ability to stimulate cAMP accumulation in synaptosomes, with the effect more pronounced with substitutes of larger volume. A certain correlation between the ability of serotonin derivatives to stimulate adenylate cyclase in vivo and in vitro, on the one hand, and their analgetic effect, on the other hand, is suggested.  相似文献   
994.
It was demonstrated that the nuclear matrix of rat liver possesses the protease activity. The specific activity of nuclear matrix proteases exceeds that of intact nuclei 7-fold. The optimum activity of nuclear matrix proteases is observed at pH 8-9. The protease activity of the nuclear matrix is inhibited by p-chloromercuribenzoate, N-ethylmaleimide, EDTA, phenylmethylsulfonyl fluoride. This suggests that thiol, serine and metalloproteases are associated with the nuclear matrix.  相似文献   
995.
Four monoclonal antibodies (mAbs), G6, F9, H8, and B2, against human alpha-1-microglobulin (A1M) have been produced and characterized. The parameters of affinity (Kp ~ 109 M?1), epitope specificity (the additively binding G6/F9, G6/H8, G6/B2, F9/H8, and F9/B2 pairs), and the observed effect of reversibility of structural changes induced by chemical agents allow use of these mAbs in biospecific methods of A1M purification and quantitative determination. The application of mAbs to an A1M enzyme immunoassay (analytical sensitivity—0.5 μg/l) and one step isolation of pure A1M by immunoaffinity chromatography was described.  相似文献   
996.
997.
998.
The electron microscopic method has revealed early maturation of the protein-synthesizing apparatus of some cells, on the one hand, and underdevelopment of neuroblast volumes, appearance of artificial contacts, axonal degeneration and destruction in large trunks, on the other hand. Compensatory-restorative processes in the cell on the 14th and 21st days of the postnatal development result in a complete restoration of morphological organization of neurons and interneuronal connections in the hypothalamus of offspring of the morphine-dependent rats.  相似文献   
999.
A comparative electrophoretic study or ejaculatory bulb proteins in 29 different Drosophila species has been carried out. In all analyzed species, ejaculatory bulb contains a major component (designated as PEB). It has molecular mass of 61-65 kDa in the species of virilis group, 33-36 kDa in species of obscura group, and 34-56 kDa in species of melanogaster group. Using immunoblotting technique, we have demonstrated that PEB is introduced into organs of female sex tract during mating. The nature and significance of revealed interspecific differences in PEB proteins has been discussed.  相似文献   
1000.
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