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   1347950篇
  免费   117992篇
  国内免费   1409篇
  2021年   18084篇
  2020年   12747篇
  2019年   16347篇
  2018年   17918篇
  2017年   16558篇
  2016年   28290篇
  2015年   42972篇
  2014年   51001篇
  2013年   77385篇
  2012年   38441篇
  2011年   27008篇
  2010年   44165篇
  2009年   45544篇
  2008年   25595篇
  2007年   23357篇
  2006年   28976篇
  2005年   29883篇
  2004年   28978篇
  2003年   26550篇
  2002年   24533篇
  2001年   34563篇
  2000年   31820篇
  1999年   31720篇
  1998年   25571篇
  1997年   25280篇
  1996年   24794篇
  1995年   22854篇
  1994年   22711篇
  1993年   21802篇
  1992年   27125篇
  1991年   25600篇
  1990年   23963篇
  1989年   24853篇
  1988年   22902篇
  1987年   21469篇
  1986年   20263篇
  1985年   22132篇
  1984年   22051篇
  1983年   19491篇
  1982年   20152篇
  1981年   19498篇
  1980年   18116篇
  1979年   17836篇
  1978年   17046篇
  1977年   16369篇
  1976年   15474篇
  1975年   14838篇
  1974年   15091篇
  1973年   15506篇
  1972年   12922篇
排序方式: 共有10000条查询结果,搜索用时 906 毫秒
901.
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   
902.
903.
904.
905.
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   
906.
907.
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   
908.
909.
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   
910.
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