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   537448篇
  免费   60119篇
  国内免费   338篇
  2018年   5290篇
  2017年   5134篇
  2016年   7064篇
  2015年   8984篇
  2014年   10694篇
  2013年   15571篇
  2012年   17349篇
  2011年   17692篇
  2010年   11900篇
  2009年   10919篇
  2008年   15445篇
  2007年   16017篇
  2006年   14920篇
  2005年   14284篇
  2004年   14153篇
  2003年   13506篇
  2002年   13036篇
  2001年   28409篇
  2000年   28248篇
  1999年   22024篇
  1998年   6799篇
  1997年   7347篇
  1996年   6778篇
  1995年   6245篇
  1994年   6031篇
  1993年   5995篇
  1992年   17070篇
  1991年   16316篇
  1990年   15731篇
  1989年   15239篇
  1988年   13951篇
  1987年   12954篇
  1986年   12066篇
  1985年   11849篇
  1984年   9691篇
  1983年   8119篇
  1982年   6029篇
  1981年   5409篇
  1980年   5127篇
  1979年   8961篇
  1978年   6833篇
  1977年   6294篇
  1976年   5673篇
  1975年   6259篇
  1974年   6784篇
  1973年   6564篇
  1972年   6000篇
  1971年   5449篇
  1970年   4698篇
  1969年   4422篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
951.
A study was made of the fatty acid composition and the content of triglycerides, phospholipids and nonesterified fatty acids (NFA) in adipose and muscle tissues of rats with alloxan diabetes. The concentration of NFA in alloxan diabetes was found to be considerably reduced in both adipose and muscle tissues. Meanwhile the content of NFA and phospholipids did not experience any substantial changes. The fatty acid composition of triglycerides of the tissues under study was characterized by considerable alterations under diabetes.  相似文献   
952.
953.
The effect of different chemical anxiolytic agents on ethanol consumption has been studied on the model of experimental alcoholism in rats. The decrease of ethanol consumption was dose-dependent. The existence of non-benzodiazepine anxiolytic systems is suggested.  相似文献   
954.
955.
Actin is a major antigen involved in the reaction of smooth muscle antibody positive sera from patients with chronic active hepatitis. In the present study, actin extracted from rabbit skeletal muscle was denatured by sodium dodecyl sulfate and was immunized into the rabbit, a homologous animal for actin. The rabbits, thus immunized, produced antibodies reactive with actins of homologous and heterologous animals. In addition, the antibodies showed reactivity with autologous actin. It indicates that the denatured homologous actin is capable of terminating immunological tolerance to actin and induces formation of autoantibody to rabbit actin. This phenomenon may be implicated in the occurrence of anti-actin antibody in sera from patients with chronic liver disease and several other diseases.  相似文献   
956.
957.
958.
959.
Mechanism of mda-5 Inhibition by Paramyxovirus V Proteins   总被引:1,自引:0,他引:1       下载免费PDF全文
The RNA helicases encoded by melanoma differentiation-associated gene 5 (mda-5) and retinoic acid-inducible gene I (RIG-I) detect foreign cytoplasmic RNA molecules generated during the course of a virus infection, and their activation leads to induction of type I interferon synthesis. Paramyxoviruses limit the amount of interferon produced by infected cells through the action of their V protein, which binds to and inhibits mda-5. Here we show that activation of both mda-5 and RIG-I by double-stranded RNA (dsRNA) leads to the formation of homo-oligomers through self-association of the helicase domains. We identify a region within the helicase domain of mda-5 that is targeted by all paramyxovirus V proteins and demonstrate that they inhibit activation of mda-5 by blocking dsRNA binding and consequent self-association. In addition to this commonly targeted domain, some paramyxovirus V proteins target additional regions of mda-5. In contrast, V proteins cannot bind to RIG-I and consequently have no effect on the ability of RIG-I to bind dsRNA or to form oligomers.  相似文献   
960.
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   
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