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   1077405篇
  免费   125817篇
  国内免费   1081篇
  2016年   12484篇
  2015年   18567篇
  2014年   21667篇
  2013年   30049篇
  2012年   34437篇
  2011年   34797篇
  2010年   23521篇
  2009年   21936篇
  2008年   31483篇
  2007年   32385篇
  2006年   30480篇
  2005年   29161篇
  2004年   29147篇
  2003年   27760篇
  2002年   27074篇
  2001年   44645篇
  2000年   44946篇
  1999年   36287篇
  1998年   14257篇
  1997年   14737篇
  1996年   13595篇
  1995年   13356篇
  1994年   13048篇
  1993年   12893篇
  1992年   30864篇
  1991年   30122篇
  1990年   29769篇
  1989年   28880篇
  1988年   26666篇
  1987年   25910篇
  1986年   24038篇
  1985年   24161篇
  1984年   20111篇
  1983年   17590篇
  1982年   13901篇
  1981年   12488篇
  1980年   11802篇
  1979年   19353篇
  1978年   15711篇
  1977年   14224篇
  1976年   13409篇
  1975年   14814篇
  1974年   16073篇
  1973年   15754篇
  1972年   14173篇
  1971年   13158篇
  1970年   11228篇
  1969年   10741篇
  1968年   9667篇
  1967年   8750篇
排序方式: 共有10000条查询结果,搜索用时 20 毫秒
991.
992.
Treatment of intestinal dysbacteriosis in children with diabetes mellitus]   总被引:1,自引:0,他引:1  
The use of the probiotic Acylact in combination with Viferone containing human recombinant interferon-alpha 2 in the treatment of intestinal dysbacteriosis in children with insulin-dependent diabetes mellitus (IDDM) was shown to be highly efficient. Elimination of microecologic disorders in the intestine was accompanied in all the children by immune rearrangements. The quantity of secretory and serum immunoglobulins and complement increased and the white blood cell chemiluminescence proved to be higher. The correction of the immune status of the children with IDDM resulted in a certain decrease of glycemia. The data are indicative of the fact that such a treatment of intestinal dysbacteriosis in children with IDDM is promising.  相似文献   
993.
994.
Published gene frequency data, checked for consistency of allele definitions across laboratories and for comparability of geographically identical samples, were pooled into a data set containing frequencies at nine loci for each of 20 populations that encompassed 10 macaque species. Genetic distances were calculated by the methods of Kidd and Cavalli-Sforza (1974). These distances were used to construct phylogenetic trees and to evaluate the relationships between divergence times and effective population sizes. Inter-and intraspecific genetic distances and the groupings defined by phenetic tree analyses support Fooden’s (1976) classification of the genus Macacainto four species groups. A paleozoogeographical model of Asia including the known times of major sea-level changes allows us to explain Macacainto four species groups. A paleozoogeographical model of Asia including the known times of major sea-level changes allows us to explain qualitatively the inferred evolutionary relationships among macaque species. Many assumptions are required in order to estimate the variables necessary in the quantitative prediction of genetic differences for a comparison between any two populations. Examination of those assumptions demonstrates the need for more accurate genetic as well as paleozoogeographic information. An erratum to this article is available at .  相似文献   
995.
Two methods for estimation of the numbers of Erwinia carotovora on potato tubers were compared using 17 naturally infected stocks. The 'wash' method estimates the surface count, whereas the 'peel' method is based on a subcuticular count. A correlation of 0.79 was obtained. Comparisons between methods were also made using a bactericide, Myacide As, and on stocks during chitting. Erwinia carotovora counts were reduced in treated tubers with the 'wash' method, but not with the 'peel' method.  相似文献   
996.
C. J. Parsons  W. P. Bobechko 《CMAJ》1982,126(3):237-243
Air transport can move patients safely and rapidly over long distances. However, changes in altitude can have disastrous effects because diminished ambient air pressure may allow gases in closed spaces and tissues to expand rapidly. Even pressurized commercial aircraft do not maintain sea-level pressure: cabin pressures equal to those at yp to 8000 ft may be experienced, diminishing oxygen tension in proportion. Air transport is absolutely contraindicated for patients with untreated pneumothorax, gas gangrene, or air trapped in the cranium and those who have recently undergone abdominal surgery. Special considerations including a planned low-altitude flight are warrented for patients who are anemic, in respiratory or cardiac distress, or immobilized in casts, or who have been engaged in underwater diving immediately before the flight.  相似文献   
997.
998.
999.
Effects of pressure on uptake and release of calcium by brain synaptosomes   总被引:1,自引:0,他引:1  
Uptake of radioactive calcium from guinea pig brain fractions enriched in synaptosomes could be significantly and reproducibly decreased by exposure to high pressure. Calcium efflux from preloaded synaptosomes was unaffected by pressure exposure. It was hypothesized that the development of pressure-induced encephalopathy may be related to an effect of pressure on the central nervous system calcium transport system.  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