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   796534篇
  免费   96465篇
  国内免费   430篇
  2016年   8961篇
  2015年   13714篇
  2014年   15710篇
  2013年   21870篇
  2012年   24964篇
  2011年   24896篇
  2010年   16798篇
  2009年   15911篇
  2008年   22683篇
  2007年   23235篇
  2006年   21732篇
  2005年   20949篇
  2004年   20675篇
  2003年   19988篇
  2002年   19405篇
  2001年   34429篇
  2000年   34835篇
  1999年   28114篇
  1998年   10861篇
  1997年   11474篇
  1996年   11001篇
  1995年   10404篇
  1994年   10262篇
  1993年   10095篇
  1992年   23664篇
  1991年   22917篇
  1990年   22536篇
  1989年   21853篇
  1988年   20147篇
  1987年   19785篇
  1986年   18153篇
  1985年   18246篇
  1984年   15180篇
  1983年   13246篇
  1982年   10607篇
  1981年   9444篇
  1980年   8987篇
  1979年   14596篇
  1978年   11729篇
  1977年   10605篇
  1976年   10015篇
  1975年   10844篇
  1974年   11657篇
  1973年   11454篇
  1972年   10240篇
  1971年   9509篇
  1970年   8134篇
  1969年   7696篇
  1968年   6871篇
  1967年   6196篇
排序方式: 共有10000条查询结果,搜索用时 484 毫秒
241.
242.
243.
In a study of intramuscular injection of quinine eight adults with moderately severe falciparum malaria resistant to chloroquine were treated with quinine dihydrochloride, being given a loading dose of 20 mg salt (16.7 mg base)/kg followed by three or four eight hourly maintenance doses of 10 mg salt (8.3 mg base)/kg injected into the anterior thigh. All patients responded to treatment. Fever and parasite clearance times (mean (SD) 60 (23) h and 53 (22) h respectively) were comparable with those obtained with intravenous quinine. The mean peak plasma quinine concentration of 11.0 mg/l (34.4 mu mol/l) [corrected] was reached a median of five hours after administration of the loading dose. In all patients plasma quinine concentrations exceeded the high minimum inhibitory concentration for Plasmodium falciparum malaria prevalent in Thailand within four hours of the start of treatment but did not cause toxicity other than mild cinchonism. When intravenous infusion is not possible an intramuscular quinine loading dose is an effective means of starting treatment in patients with moderately severe falciparum malaria who cannot swallow tablets.  相似文献   
244.
In this paper the recent population changes of the Wild Boar in different European countries is analysed through the study of hunting statistics. A simultaneous increase in numbers is observed throughout the whole area during the period 1965–1975. From 1975 onwards the population stabilizes itself apart from in peripheral areas like Finland. Potentially favourable factors which play a part in this process are discussed and certain reproductive and dispersive characteristics which favour its invasive behaviour are discussed.  相似文献   
245.
246.
247.
We studied recipient mating ability in the presence of excess F'lac donors. Ninety-five percent of recipients were able to receive F'lac in 30-min matings. Competition between an F'-lac donor and an F'lac traI donor, which mobilized a ColE1 derivative (pML2), showed that each recipient mated with an average of two to three donors in 30 min. Experiments in which the competing donor was added at different times showed that some competition occurred throughout the 30-min mating period, which suggested that aggregate formation was spread over this time.  相似文献   
248.
249.
Administration of purified pertussis toxin to rats induced persistent tachycardia, (observed in conscious rats but not after pithing); as little as 0.05 microgram/100 g produced a significant effect. Pertussis toxin-treatment did not affected the pressor response produced in the pithed rats by the alpha 2-adrenergic agonist methoxamine but markedly diminished the pressor effect of the alpha 2-adrenergic agonists clonidine and azepexole. A role of adenylate cyclase inhibition in the action of postsynaptic vascular alpha 2-adrenergic receptors is suggested.  相似文献   
250.
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