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   749878篇
  免费   81106篇
  国内免费   355篇
  831339篇
  2018年   6389篇
  2016年   8418篇
  2015年   11227篇
  2014年   13161篇
  2013年   19831篇
  2012年   21642篇
  2011年   22226篇
  2010年   15030篇
  2009年   13921篇
  2008年   19992篇
  2007年   20663篇
  2006年   19655篇
  2005年   18689篇
  2004年   18733篇
  2003年   18087篇
  2002年   17739篇
  2001年   31880篇
  2000年   31992篇
  1999年   25901篇
  1998年   9334篇
  1997年   9879篇
  1996年   9466篇
  1995年   8725篇
  1994年   8752篇
  1993年   8648篇
  1992年   22359篇
  1991年   21743篇
  1990年   21551篇
  1989年   21471篇
  1988年   19868篇
  1987年   18849篇
  1986年   17566篇
  1985年   18019篇
  1984年   14862篇
  1983年   12854篇
  1982年   9819篇
  1981年   8797篇
  1980年   8384篇
  1979年   14249篇
  1978年   11111篇
  1977年   10282篇
  1976年   9872篇
  1975年   10738篇
  1974年   11509篇
  1973年   11199篇
  1972年   10396篇
  1971年   9345篇
  1970年   8133篇
  1969年   7814篇
  1968年   7197篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
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   
992.
993.
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   
994.
995.
The pH, the osmolality and the urea and ammonia concentrations in blood, as well as the net urea and ammonia excretions, were studied in the amphibian Xenopus laevis exposed for several weeks to increased osmotic pressure (OP) of the ambient water, as a result of the addition of either NaCl or mannitol to the water. The pH and the ammonia concentration of the blood were independent of the variations of the ambient osmolarity. On the contrary, the blood osmolality and its urea concentration increased markedly when the ambient OP was augmented. The increase of ambient OP by NaCl addition to the medium augmented the urea net excretion and slightly decreased the ammonia excretion. When the increase of ambient OP resulted from the addition of mannitol in the water, excretions of urea and ammonia became negligible.  相似文献   
996.
Phenotypic data on 203 Gram-negative non-fermentative bacteria of the Flavobacterium-Cytophaga group isolated from milk and butter were analyzed by numerical taxonomic techniques. Twenty reference strains including species of Flavobacterium, Cytophaga and strains of Pseudomonas paucimobilis were included in the study. Using the matching coefficient of Sokal & Michener with antibiotic susceptibility data included, 139 isolates were recovered in nine clusters. Six of these clusters were linked at or above the 85% S level while three were linked at or above the 79% S level. The largest cluster, representing 46.3% of the isolates, could be equated with Flavobacterium sp. Group IIb. Other clusters could be equated with Flavobacterium sp. L 16/1 (22.7% of isolates), F. balustinum (10.8% of isolates), F. breve (4.4%), F. multivorum (3.5%) and Cytophaga johnsonae (1.5%). The cluster resembling Flavobacterium sp. L 16/1 and a smaller unclassified cluster, were exceptional in being susceptible to the antibiotics cephalothin and penicillin G.  相似文献   
997.
Fractionation of human erythrocyte membrane proteins was performed using a modification of two-dimensional gel electrophoresis described by P. O'Farrel with isoelectric point plotted against molecular mass. All major erythrocyte proteins, including high molecular weight proteins, such as spectrin and band 3 protein, identified by one-dimensional sodium dodecyl sulfate gel electrophoresis, were visualized by silver staining of two-dimensional gels. All in all about 50 polypeptides were distinguished on two-dimensional electrophoretic patterns. Preliminary protein map was developed.  相似文献   
998.
999.
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   
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