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   709402篇
  免费   48965篇
  国内免费   1325篇
耳鼻咽喉   9216篇
儿科学   23299篇
妇产科学   17714篇
基础医学   110738篇
口腔科学   20065篇
临床医学   63954篇
内科学   135246篇
皮肤病学   16238篇
神经病学   49745篇
特种医学   25861篇
外国民族医学   76篇
外科学   104883篇
综合类   14853篇
现状与发展   2篇
一般理论   161篇
预防医学   51540篇
眼科学   16461篇
药学   54213篇
  3篇
中国医学   2365篇
肿瘤学   43059篇
  2021年   5505篇
  2018年   7917篇
  2017年   6151篇
  2016年   6869篇
  2015年   7629篇
  2014年   10336篇
  2013年   15499篇
  2012年   20670篇
  2011年   21661篇
  2010年   12830篇
  2009年   12021篇
  2008年   20130篇
  2007年   21669篇
  2006年   22053篇
  2005年   20576篇
  2004年   20142篇
  2003年   19084篇
  2002年   18606篇
  2001年   36456篇
  2000年   37016篇
  1999年   30496篇
  1998年   7912篇
  1997年   6689篇
  1996年   6997篇
  1995年   6648篇
  1994年   6118篇
  1993年   5610篇
  1992年   23041篇
  1991年   22997篇
  1990年   22381篇
  1989年   22155篇
  1988年   20115篇
  1987年   19497篇
  1986年   18543篇
  1985年   17364篇
  1984年   12746篇
  1983年   10775篇
  1982年   5940篇
  1979年   11540篇
  1978年   8138篇
  1977年   6850篇
  1976年   6602篇
  1975年   7291篇
  1974年   8519篇
  1973年   8161篇
  1972年   7673篇
  1971年   7145篇
  1970年   6896篇
  1969年   6322篇
  1968年   5791篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
111.
For many parents stopping life-sustaining medical treatment on their dying infant is psychologically impossible. Dostoevsky's insights into human behavior, particularly the fact that individuals do not want the anxiety and guilt associated with responsibility for making difficult decisions, might change the way physicians approach parents for permission to withdraw life-prolonging medical interventions on dying infants.  相似文献   
112.
A series of 1-alkyl-3,4-dihydroisoquinolines and the related 4-alkyl-1,2-dihydro-benzo[f]isoquinolines was synthesized using reactions of dialkylbenzylcarbinols and their naphthyl analogs with alkylcyanides. Experiments showed that 1-alkyl-6,7-dimethoxy-3,4-dihydroisoquinolines typically produce a hypotensive action, while the benzo-annelated structures usually exhibit a hypertensive effects. The most active compound decreases the arterial pressure in cats by 52 Torr and the effect lasts for about 4 hours. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 40, No. 3, pp. 15–17, March, 2006.  相似文献   
113.
Extracts of the above-ground part of meadowsweet (Filipendula ulmaria L. Maxim.) demonstrate a pronounced antioxidant activity. It is established that 70% and 95% ethanol extracts contain the most active substances. Investigation of the chemical composition of the above-ground part of the plant and its 70% ethanol extract by means of qualitative reactions, thin-layer chromatography, and paper chromatography showed the presence of various phenolic compounds, including quercetin and its glycosides, dihydroquercetin, apigenin, rododendrol, esculetin, and m-hydroxybenzoic, salicylic, anisic, gallic, gentisic, ferulic, chlorogenic, and caffeic acids. __________ Translated From Khimiko-Farmatsevticheskii Zhurnal, Vol. 40, No. 12, Pp. 22–24, December, 2006.  相似文献   
114.
115.
116.
117.
OBJECTIVE: To study the effect of high-frequency (100 Hz) repetitive conditioning electrical stimulation (CES, 10 min) on human somatosensory evoked potentials (SEPs) to evaluate if short-term cortical plasticity could be induced. METHODS: Painful electrical stimulations were applied to thumb (D1) and little finger (D5) fingertips, respectively. The 124-channel EEG was recorded from 10 healthy male volunteers. Peak stages around 34, 45, 212, 331 ms were analyzed with focal maximum amplitude (FA) and area magnitude (AM) of scalp field potential, topography, and equivalent current dipole source localisation, comparing before and after two-level CES (high- vs. low-level) applied to the He-Gu acupoint. RESULTS: After a high-level CES, the positive FA and AM of the current efflux showed a significant increase at the early phase 34 ms, and significantly decreased at 45 ms in D1 SEPs. The negative FA and AM of the current influx were significantly increased at late phase 350 ms of the D5 SEPs. Only 36 ms, the z-axis position of dipole was significantly changed from (x: -15.9 mm, y: 29.6 mm, z: 43.9 mm) to (x: -12.9 mm, y: 29.4mm, z: 51.5mm) for the D5 SEPs. CONCLUSIONS: The high-level CES significantly attenuated the subsequent cortical activation (45 ms peak for D1 stimulation). Both low- and high-level CES significantly enhanced the late activities (226, 350 ms) in D5 stimulation. This may be explained by pain sensation change at the level of subcortical cingulate cortex induced by the site-dependent post-effect of CES. SIGNIFICANCE: This study showed cortical plasticity induced by conditioning somatosensory stimulation.  相似文献   
118.
119.
120.
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