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   1672946篇
  免费   161905篇
  国内免费   1615篇
  1836466篇
  2021年   18362篇
  2019年   16402篇
  2018年   19581篇
  2017年   18152篇
  2016年   29653篇
  2015年   43757篇
  2014年   52016篇
  2013年   78364篇
  2012年   48632篇
  2011年   39840篇
  2010年   47923篇
  2009年   48046篇
  2008年   36245篇
  2007年   35149篇
  2006年   37836篇
  2005年   38746篇
  2004年   37793篇
  2003年   34933篇
  2002年   32671篇
  2001年   55482篇
  2000年   53286篇
  1999年   47374篇
  1998年   27983篇
  1997年   27912篇
  1996年   26874篇
  1995年   25011篇
  1994年   24734篇
  1993年   24047篇
  1992年   39468篇
  1991年   37510篇
  1990年   35823篇
  1989年   36177篇
  1988年   33092篇
  1987年   31358篇
  1986年   29535篇
  1985年   30833篇
  1984年   28786篇
  1983年   25100篇
  1982年   23518篇
  1981年   22411篇
  1980年   20950篇
  1979年   25037篇
  1978年   21974篇
  1977年   20943篇
  1976年   19692篇
  1975年   19670篇
  1974年   20659篇
  1973年   20831篇
  1972年   17976篇
  1971年   16467篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
961.
The effect of the pentapeptide H-Cys-Tyr-Ile-Gln-Asn-OH to act like melanocyte-stimulating hormone-releasing factor (MSH-RF) was studied. This peptide decreases at ng amounts the MSH content of the rat pituitary and increases plasma MSH concentration. This agent also stimulates the release of MSH in animals with eminence lesion, indicating a direct action of the pentapeptide on the gland.  相似文献   
962.
963.
964.
Five cases of coincident salmonellosis and ulcerative colitis are described. In three the diagnostic combination was recognized late. If corticosteroid therapy is given for the colitis once the combination is recognized, then simultaneous systemic antibiotic cover is advisable. One of the five patients died during corticosteroid therapy alone with salmonella septicaemia due to a usually non-invasive organism.  相似文献   
965.
966.
Seven patients with “coeliac axis compression syndrome” are reported. Five were treated surgically, but only two did well. A survey of 200 healthy adults showed epigastric bruits in 6·5%; only one of these had dyspepsia, though dyspepsia was present in 12·5% overall.Caution is urged in attributing a causal relationship between coeliac axis compression and pain and in proceeding to arteriography when compression is suspected on clinical grounds.  相似文献   
967.
From experience in the Northampton/Kettering area 9 to 10% of all patients in a general hospital requiring care in an intensive therapy unit were aged 12 years or under. Fifty-nine children were admitted to the intensive therapy unit of Northampton General Hospital between May 1967 and August 1969. Of these, 22 had been injured in road traffic accidents, five were surgical emergencies, five had meningitis, four status epilepticus, and four respiratory infections.All of the 30 families interviewed were in favour of their child being admitted to the unit, and none considered that the experience had had any lasting adverse psychological effect on the child. It is suggested that certain carefully selected child patients do benefit from the facilities of an intensive therapy unit, and for this reason such units must be designed, equipped, and staffed with this in mind.  相似文献   
968.
T S Il'ina 《Genetika》1986,22(11):2572-2582
The published data on molecular mechanisms of transposons movement inside and between genomes are reviewed. The replicative mechanism of transposition of the family of Tn3-like elements is discussed, as well as the modes of bacteriophage Mu, Tn9, Tn10, Tn903 transposition. The factors affecting the choice of transposition pathways are analysed.  相似文献   
969.
S ummary . This paper describes the development and use of a selective diagnostic medium for the detection and enumeration of Clostridium perfringens in foods. The medium gives higher counts of Cl. perfringens and fewer false positives than existing media.  相似文献   
970.
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