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   1051894篇
  免费   126174篇
  国内免费   582篇
  2016年   11852篇
  2015年   17545篇
  2014年   20210篇
  2013年   28664篇
  2012年   32260篇
  2011年   32468篇
  2010年   22081篇
  2009年   20788篇
  2008年   29513篇
  2007年   30272篇
  2006年   28379篇
  2005年   27295篇
  2004年   26879篇
  2003年   26136篇
  2002年   25328篇
  2001年   44795篇
  2000年   45338篇
  1999年   36339篇
  1998年   14110篇
  1997年   14895篇
  1996年   14234篇
  1995年   13468篇
  1994年   13213篇
  1993年   13206篇
  1992年   31025篇
  1991年   30241篇
  1990年   29567篇
  1989年   28906篇
  1988年   26663篇
  1987年   26059篇
  1986年   24256篇
  1985年   24346篇
  1984年   20268篇
  1983年   17720篇
  1982年   14032篇
  1981年   12663篇
  1980年   12111篇
  1979年   19701篇
  1978年   15806篇
  1977年   14403篇
  1976年   13649篇
  1975年   14873篇
  1974年   15848篇
  1973年   15560篇
  1972年   14037篇
  1971年   12970篇
  1970年   11099篇
  1969年   10613篇
  1968年   9505篇
  1967年   8519篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
971.
Anaerobic ureolytic bacteria from caecal content and soft faeces of rabbit   总被引:2,自引:0,他引:2  
Forty strains of ureolytic bacteria were isolated from the caecal content and soft faeces of seven rabbits by the anaerobic roll tube method and were characterized. The isolates were identified with Clostridium coccoides, Cl. innocuum, Peptostreptococcus productus, P. micros, Peptococcus magnus, Fusobacterium russii and Fusobacterium sp. Urease activity of representative strains of the various species was also determined. The study indicated that strongly-ureolytic anaerobic bacteria are present in the caecum of the rabbit.  相似文献   
972.
The effects of the decamethyloctadehydrocorrine-cobalt complex (Co-C) on respiration and the ATP-synthetase activity of rat liver mitochondria were investigated. The Co-C complex was found to be an effective shunt of the respiratory chain. It accepts electrons from ubiquinone and donates them directly to O2. The Co-C complex inhibits the ATPase and ATP-synthetase activities of mitochondria.  相似文献   
973.
974.
975.
These siblings of a Czech family aged 21, 19 and 6 years, respectively, with congenital dyserythropoietic anemia, type II, (HEMPAS) are reported. In two elder siblings ferrokinetic studies revealed a rapid plasma 59Fe clearance, markedly decreased erythrocyte incorporation and shortened 51Cr red-cell survival. Direct anti-globulin test was found positive in one of them. Further investigations revealed low values of blood plasma cholesterol, total lipids, beta-lipoproteins, beta-carotine and vitamin E and A as well as low values of the prothrombin complex. Liver biopsy demonstrated siderosis and disseminated intravascular coagulation in the liver in both patients. The possible reasons for these humoral aberrations are discussed.  相似文献   
976.
977.
978.
The Pig chromosomes that contain rDNA sites displayed a polymorphism in the distribution of the genes among the nucleolar organizers located on pairs Nos. 8 and 10. Two, or more often three, active sites were observed in the chromosomes of lymphocytes stimulated with phytohemagglutinin. Only 5% of the metaphases showed a 4th small active site. At the onset of stimulation most cells contained one-two nucleoli; four nucleoli were never observed. After prolonged stimulation, the number of nuclei containing three nucleoli increased. A 4th small nucleolus appeared in a few cells, presumably formed by activation of the smallest rDNA site.  相似文献   
979.
J L Weber  E Cutz 《CMAJ》1980,123(2):112-117
  相似文献   
980.
Treatment of bacteriological-grade plastic with concentrated sulphuric acid is a well known technique which increases the wettability of the surface and renders it suitable for eukaryotic cell adhesion. We have noticed that these substrata present a distinctive surface topography in the presence of a serum supplement under normal culture conditions. The adsorbed serum layer is comprised of fine furrows and ridges and the influence of adherent cells on this layer leads to minute tears and distortions in the direction of the corrugations. This provides a novel system for the investigation of cell spreading and locomotion by scanning electron microscopy.  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