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   228377篇
  免费   15143篇
  国内免费   46篇
  2021年   1804篇
  2018年   3204篇
  2017年   3094篇
  2016年   3755篇
  2015年   3270篇
  2014年   4539篇
  2013年   6503篇
  2012年   7940篇
  2011年   8666篇
  2010年   5984篇
  2009年   4944篇
  2008年   7596篇
  2007年   7850篇
  2006年   7495篇
  2005年   6989篇
  2004年   7071篇
  2003年   6783篇
  2002年   6684篇
  2001年   9322篇
  2000年   9061篇
  1999年   7041篇
  1998年   2152篇
  1997年   1964篇
  1996年   1828篇
  1992年   5485篇
  1991年   5689篇
  1990年   5661篇
  1989年   5630篇
  1988年   5219篇
  1987年   4877篇
  1986年   4448篇
  1985年   4693篇
  1984年   3716篇
  1983年   3031篇
  1982年   2026篇
  1981年   1731篇
  1980年   1738篇
  1979年   3347篇
  1978年   2586篇
  1977年   2384篇
  1976年   2345篇
  1975年   2837篇
  1974年   3135篇
  1973年   3092篇
  1972年   2754篇
  1971年   2613篇
  1970年   2220篇
  1969年   2160篇
  1968年   2035篇
  1967年   1805篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
201.
Experiments in mice have demonstrated that in the presence of influenza infection the suppressing effect of virulent shigellae on the secondary humoral and cell-mediated immune response is enhanced. Under such conditions avirulent shigellae can also show suppressing effect which is usually absent in these organisms.  相似文献   
202.
It has been shown that at late periods after immobilization stress there is an essential reduction in the cytostatic activity of CBA mice splenocytes detected by inhibition of mastocytoma P 815 cell proliferation in the test with 3H-uridine incorporation. The cytostatic activity returns to normal 5 to 14 days after stress. The changes in the cytolytic and cytostatic activity of mouse splenocytes following stress are correlated and a possible biological value of changes in the immunoassays for the host are discussed.  相似文献   
203.
The processes of the cultivation of N. meningitidis, serogroups A, B and C, in a liquid synthetic culture medium have been studied. Strictly group-specific biomass has been obtained. The maximum productivity at all stages of the batch cultivation of N. meningitidis strains 125 and 133 in this medium does not differ from that at similar stages of cultivation in modified Cohen-Wheller semisynthetic medium. In the serotype antigen preparations obtained from N. meningitidis strain 125 grown in the above-mentioned liquid synthetic culture medium basic polypeptides with a molecular weight of 33000, 36000 and 41000 D have been detected. Their presence in N. meningitidis cells is linked with the growth phase of the population.  相似文献   
204.
In has been shown that cortisol immobilized on polyvinylpyrrolidone (PVP-GC) affects cyclic AMP production stimulated by adenosine and isoproterenol in rat thymocytes. This effect of PVP-GC is specific for cortisol: antiglucocorticoid progesterone (at a concentration of 10(-5) M) inhibited completely the action of PVP-GC on the intracellular cAMP level. It is suggested that cortisol effect on cAMP production is one of the mechanisms of glucocorticoid hormone action in target cells.  相似文献   
205.
206.
A new cestode species, Diphyllobothrium klebanovskii sp. n., is described on the basis of experimental examination and morphological study of 51 specimens expelled from men in lower part of the Amur river and 18 specimens expelled from golden hamsters. The larval stage of this cestode is plerocercoid of type F, which is localized in muscles of Oncorhynchus keta and O. gorbuscha. D. klebanovskii sp. n. is a marine species, it differs from D. latum and other species of the genus Diphyllobothrium.  相似文献   
207.
208.
Biophysics - HMGB1 is one of the key proteins of the cell. HMGB1 performs its main functions predominantly in the cell nucleus, as an essential component of DNA–protein and multiprotein...  相似文献   
209.
Murina  M. A.  Roshchupkin  D. I.  Sergienko  V. I. 《Biophysics》2021,66(4):535-540
Biophysics - A technology has been developed for the preparation of novel chloramine compounds related to adenosine derivatives. The optical absorption characteristics of...  相似文献   
210.
Vorobieva  V. V.  Shabanov  P. D. 《Biophysics》2021,66(4):610-613
Biophysics - A change in the content of energy substrates in myocardial mitochondria depending upon the vibration frequency and the duration of the total vertical vibration exposure was studied...  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