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   1253772篇
  免费   98638篇
  国内免费   1333篇
  2021年   17693篇
  2020年   12599篇
  2019年   16122篇
  2018年   18280篇
  2017年   17123篇
  2016年   28310篇
  2015年   42144篇
  2014年   50094篇
  2013年   76371篇
  2012年   33624篇
  2011年   22050篇
  2010年   43728篇
  2009年   45051篇
  2008年   21157篇
  2007年   19007篇
  2006年   24362篇
  2005年   25861篇
  2004年   24876篇
  2003年   22471篇
  2002年   20664篇
  2001年   26136篇
  2000年   23265篇
  1999年   25828篇
  1998年   24507篇
  1997年   24106篇
  1996年   23811篇
  1995年   21925篇
  1994年   21802篇
  1993年   20762篇
  1992年   22799篇
  1991年   21490篇
  1990年   20341篇
  1989年   21456篇
  1988年   19672篇
  1987年   18536篇
  1986年   17647篇
  1985年   19908篇
  1984年   20347篇
  1983年   17961篇
  1982年   19035篇
  1981年   18486篇
  1980年   17291篇
  1979年   16130篇
  1978年   15899篇
  1977年   15383篇
  1976年   14806篇
  1975年   14230篇
  1974年   14549篇
  1973年   15016篇
  1972年   12490篇
排序方式: 共有10000条查询结果,搜索用时 428 毫秒
871.
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   
872.
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   
873.
874.
875.
876.
877.
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   
878.
879.
Pieces of brain are fixed in formalin ammonium bromide for about 4 days at room temperature, and given the following treatment: After washing, dehydrating and clearing, embed in paraffin, section and mount. Deparaffinize sections and pass through graded alcohols to water. Sensitize in 5% sodium sulfite for 2 hours, wash in distilled water and impregnate with silver diamminohydroxide solution 2-5 minutes at room temperature. Reduce in 2% formalin, wash in distilled water and tone in gold chloride. Fix in 5% hypo, counterstain with 1% picric acid, dehydrate and cover in balsam. Equally good results are obtained by impregnating with Hortega's strong silver carbonate. The microglia, oligodendroglia, fibrous and protoplasmic astrocytes in the cat, rabbit, newborn and adult human are successfully stained by this method.  相似文献   
880.
The [3H]ketanserin binding characteristics in the apomorphine-induced aggressive and nonaggressive adult male Wistar rats were studied. Repeated apomorphine (0.5 mg/kg, once daily) treatment gradually induced aggressive behaviour in sixteen animals from twenty. Thereafter the animals were retrospectively divided into apomorphine-induced aggressive and nonaggressive group. The maximal number of the [3H]ketanserin binding sites was increased in the apomorphine-treated animals in the frontal (233.9+/-26.5, 364.6+/-31.7, and 367.0+/-34.8 fmol/mg protein for the vehicle, apomorphine-nonaggressive, and apomorphine-aggressive group, respectively) and cerebral cortex (164.2+/-6.7, 289.7+/-29.3, and 249.0+/-15.4 fmol/mg protein for the vehicle, apomorphine-nonaggressive, and apomorphine-aggressive group, respectively). In conclusion, our experiments demonstrate that repeated apomorphine treatment upregulates the maximal number of the 5-HT2A receptors in rat frontal and cerebral cortex as measured by [3H]ketanserin binding and this phenomenon is independent from the development of aggressive behaviour.  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