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   1808426篇
  免费   174629篇
  国内免费   2321篇
  1985376篇
  2021年   18585篇
  2019年   16411篇
  2018年   20078篇
  2017年   18886篇
  2016年   29982篇
  2015年   44010篇
  2014年   52187篇
  2013年   78514篇
  2012年   53846篇
  2011年   46563篇
  2010年   49596篇
  2009年   49123篇
  2008年   42138篇
  2007年   41383篇
  2006年   43482篇
  2005年   44278篇
  2004年   43334篇
  2003年   40417篇
  2002年   38165篇
  2001年   59853篇
  2000年   57920篇
  1999年   51034篇
  1998年   28651篇
  1997年   28560篇
  1996年   27507篇
  1995年   25712篇
  1994年   25242篇
  1993年   24613篇
  1992年   43417篇
  1991年   41593篇
  1990年   40092篇
  1989年   40263篇
  1988年   37225篇
  1987年   35171篇
  1986年   33197篇
  1985年   34538篇
  1984年   31542篇
  1983年   27434篇
  1982年   24863篇
  1981年   23487篇
  1980年   21916篇
  1979年   27596篇
  1978年   24064篇
  1977年   22519篇
  1976年   21178篇
  1975年   21924篇
  1974年   23041篇
  1973年   23249篇
  1972年   20230篇
  1971年   18530篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
962.
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   
963.
964.
965.
The capillaries of the cardiac muscle were investigated in the goat by means of light microscopy, transmission electron microscopy and scanning electron microscopy, and the following results were obtained. The capillaries of the working cardiac muscles were numerous, arranged mainly parallel to the long axis of muscle cells and formed dense elongated networks. On the contrary, those of the terminal Purkinje fibers were relatively few in number, oriented in various directions and formed loose and circularly meshed networks surrounding the fibers. Such findings were discussed in correlation with the physiology and functional morphology of various types of the cardiac muscle cells.  相似文献   
966.
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   
967.
968.
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   
969.
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   
970.
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   
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