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   642550篇
  免费   67841篇
  国内免费   418篇
  2016年   7037篇
  2015年   9476篇
  2014年   11032篇
  2013年   16650篇
  2012年   18009篇
  2011年   18669篇
  2010年   12590篇
  2009年   11637篇
  2008年   16811篇
  2007年   17552篇
  2006年   16611篇
  2005年   15840篇
  2004年   15796篇
  2003年   15425篇
  2002年   15072篇
  2001年   26271篇
  2000年   26369篇
  1999年   21097篇
  1998年   7672篇
  1997年   8197篇
  1996年   7826篇
  1995年   7220篇
  1994年   7061篇
  1993年   7120篇
  1992年   18314篇
  1991年   18125篇
  1990年   17881篇
  1989年   17659篇
  1988年   16480篇
  1987年   15645篇
  1986年   14480篇
  1985年   15090篇
  1984年   12526篇
  1983年   10720篇
  1982年   8345篇
  1981年   7551篇
  1980年   7098篇
  1979年   12053篇
  1978年   9425篇
  1977年   8947篇
  1976年   8440篇
  1975年   9188篇
  1974年   10111篇
  1973年   9943篇
  1972年   9133篇
  1971年   8357篇
  1970年   7334篇
  1969年   7235篇
  1968年   6660篇
  1967年   5778篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
911.
A sugar-binding component was shown to be present at the surface of endoerythrocytic Plasmodium berghei and P. chabaudi stages and merozoites by means of a panel of neoglycoproteins using fluorescence microscopy and flow cytofluorometry. The protein nature of this material was ascertained by the loss of sugar-binding capacity upon trypsin treatment. This lectin-like protein primarily bound neoglycoprotein-borne N-acetylglucosamine and secondarily bound neoglycoprotein-borne alpha-D-glucose, beta-D-galactose and alpha-L-fucose. These results suggest the presence of at least one type of lectin-like protein with an extended binding site accomodating several sugar units, and define its localization on the parasite surface.  相似文献   
912.
913.
The regenerating scale and tissues comprising the scale pocket of Fundulus olivaceus were examined microscopically at specific intervals. Scale removal resulted in a thickening of the epidermis which persisted through the early stages of regeneration. This thickening was due in part to the appearance of columnar basal cells which divided producing cells that became mucous cells and squamous cells. The scale regenerated as a relatively large plate of bone which first appeared between layers of scleroblasts on the floor of the scale pocket and then grew producing circuli and radii. By the fourth day of regeneration, calcium was observed in the cytoplasm of the scleroblasts and at randomly distributed foci in the osseous portion of the scale. The osseous layer was completely calcified by 15 days of regeneration.  相似文献   
914.
915.
The study of the effect of gamma globulin introduced in different doses (0.5 and 0.25 ml/mg) in combination with Fermi rabies vaccine (observations on humans were made) and with cerebral rabies vaccine inactivated by UV irradiation (in animal experiments) demonstrated that the injection of the higher doses of gamma globulin resulted in lower geometrical mean of antibody titers. Therefore, in combined administration of rabies vaccine and gamma globulin for postexposure rabies prevention it is advisable to reduce the dose of gamma globulin by one-half.  相似文献   
916.
Summary Viral leukemogenesis in mice is frequently initiated by proviral activation of a highly conserved cellular gene called Pim-1. Here we report the chromosomal localization of the human homologue by Southern blot analyses of DNAs obtained from human-rodent somatic cell hybrids. The single copy human homologue was assigned to the 6pter-q12 segment.  相似文献   
917.
918.
919.
920.
During an ultrastructural study of small-intestinal mucosa from a patient suffering from alpha-chain disease organisms were identified within the epithelial cytoplasm which showed the fine structural features of the coccidian group. Though coccidiosis is well recognized as causing a diarrhoeal and often lethal illness in animals it has been neglected as a cause of disease in man. Thus this finding may be significant and warrants further investigation into its possible role in the pathogenesis of alpha-chain disease.  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