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   796515篇
  免费   82478篇
  国内免费   250篇
  879243篇
  2018年   7930篇
  2017年   7580篇
  2016年   10634篇
  2015年   13450篇
  2014年   16023篇
  2013年   23134篇
  2012年   25979篇
  2011年   26757篇
  2010年   18268篇
  2009年   16888篇
  2008年   23914篇
  2007年   24881篇
  2006年   23258篇
  2005年   22368篇
  2004年   22145篇
  2003年   21306篇
  2002年   20816篇
  2001年   34739篇
  2000年   34195篇
  1999年   27574篇
  1998年   10182篇
  1997年   10269篇
  1996年   9846篇
  1995年   9060篇
  1994年   8722篇
  1993年   8752篇
  1992年   22334篇
  1991年   21920篇
  1990年   21368篇
  1989年   20812篇
  1988年   19084篇
  1987年   18323篇
  1986年   17093篇
  1985年   16956篇
  1984年   13934篇
  1983年   12181篇
  1982年   9231篇
  1981年   8355篇
  1980年   7755篇
  1979年   12938篇
  1978年   10202篇
  1977年   9194篇
  1976年   8803篇
  1975年   9816篇
  1974年   10484篇
  1973年   10350篇
  1972年   9478篇
  1971年   8456篇
  1970年   7385篇
  1969年   7255篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Arundo donax L. (Poaceae) is native to Mediterranean Europe and invasive in the Rio Grande Basin of North America. Rhizomes from nine sites in France and Spain infested with a candidate control agent, the armoured scale Rhizaspidiotus donacis (Hemiptera: Diaspididae) weighed 50% less than those from nine sites without scale.  相似文献   
992.
993.
994.
995.
Fourteen fresh run salmon Satmo salar L. with early extant lesions of ulcerative dermal necrosis (UDN) were kept in separate tanks and treated with zinc free malachite green. Ten of the fish were held at 10° C and 4 at 2° C. The treatment precluded infection with Saprolegnia fungus and allowed natural resolution of the lesions. There was a marked difference in rate of healing between warm and cold water conditions.
Histological examination of healing lesions at different stages showed that there was a primary invasion of cuboidal epithelium over the collagen scar followed by a phase of disorganized proliferation which eventually organized itself into normal epithelium. Melanocytes were very obvious in the dermis of healing lesions.  相似文献   
996.
997.
Sequential poly(Arg-Thr-Lys-Pro) consisting mainly of the repeat of tuftsin Thr-Lys-Pro-Arg was synthesized by condensing the p-nitrophenyl ester of Arg(HCl)-Thr-Lys-(2-Cl-Z)-Pro in the presence of HOBt. Two haptenic sequences of the Pre-S region of hepatitis B virus antigen (10-26 and 39-55) were prepared by solid phase and coupled to polytuftsin via glutaraldehyde. The peptides, either free or coupled to polytuftsin, were administrated to mice and the antisera were assayed by ELISA. Coupling the peptides to the polypeptide significantly improved the anti-peptide antibody titer in Freund complete adjuvant or in NaCl 0.9%. Cross-reaction between antibodies induced by the peptides and the native protein was also improved. Polytuftsin alone is very poorly immunogenic.  相似文献   
998.
999.
1000.
Focal contacts of spreading platelets with the substratum   总被引:1,自引:0,他引:1  
Contacts with glass substratum formed by the spreading rabbit platelets were examined by an antibody-exclusion method; monoclonal antibodies against 80 kD bovine serum protein were used. It was found that platelets form focal contacts in the course of spreading. The size of the largest focal contacts formed by platelets is smaller than that of the contacts formed by fibroblasts. The antibody-exclusion method revealed focal contacts of platelets much more clearly than interference reflection microscopy (IRM). The similarity of reactions involved in spreading platelets and of large nucleus-containing tissue cells is discussed.  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