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   706146篇
  免费   48962篇
  国内免费   1306篇
耳鼻咽喉   9167篇
儿科学   23275篇
妇产科学   17608篇
基础医学   110509篇
口腔科学   19960篇
临床医学   63800篇
内科学   134401篇
皮肤病学   16164篇
神经病学   49437篇
特种医学   25761篇
外国民族医学   76篇
外科学   104504篇
综合类   14822篇
现状与发展   2篇
一般理论   160篇
预防医学   51439篇
眼科学   16318篇
药学   53968篇
  3篇
中国医学   2359篇
肿瘤学   42681篇
  2019年   5434篇
  2018年   7863篇
  2017年   6107篇
  2016年   6825篇
  2015年   7552篇
  2014年   10272篇
  2013年   15391篇
  2012年   20507篇
  2011年   21502篇
  2010年   12726篇
  2009年   11945篇
  2008年   19995篇
  2007年   21515篇
  2006年   21909篇
  2005年   20458篇
  2004年   20002篇
  2003年   18958篇
  2002年   18465篇
  2001年   36342篇
  2000年   36911篇
  1999年   30383篇
  1998年   7889篇
  1997年   6672篇
  1996年   6984篇
  1995年   6643篇
  1994年   6100篇
  1993年   5598篇
  1992年   22991篇
  1991年   22933篇
  1990年   22313篇
  1989年   22085篇
  1988年   20042篇
  1987年   19421篇
  1986年   18469篇
  1985年   17310篇
  1984年   12700篇
  1983年   10742篇
  1982年   5922篇
  1979年   11526篇
  1978年   8131篇
  1977年   6834篇
  1976年   6598篇
  1975年   7268篇
  1974年   8501篇
  1973年   8142篇
  1972年   7663篇
  1971年   7130篇
  1970年   6880篇
  1969年   6308篇
  1968年   5783篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
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   
42.
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   
43.
44.
45.
46.
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   
47.
48.
49.
50.
OBJECTIVE: To evaluate the reproducibility of sonographic measurement of the lower uterine segment in pregnant women at term. METHODS: Two independent observers performed transabdominal sonography on 129 women between 36 and 38 weeks of gestation who had had a previous Cesarean section. Sonography was performed when the patients had a full and a half-full bladder; in 100 patients, the measurements were also performed transvaginally, with the patients having an empty bladder. Agreement was quantified by the intraclass correlation coefficient and, using a cut-off of 3.5 mm, by the kappa coefficient. RESULTS: The intraobserver agreement was generally high (intraclass correlation coefficient > 0.90). The interobserver agreement was higher on transvaginal (intraclass correlation coefficient, 0.94) compared with transabdominal (0.70 and 0.84, with full and half-full bladder, respectively) ultrasound. The kappa coefficient was 0.75 transvaginally, compared with 0.34 and 0.54 using the transabdominal approach, with full and half-full bladder, respectively. CONCLUSION: The agreement between two observers for sonographic transvaginal measurement of the lower uterine segment can be considered good, compared with poor to moderate agreement using the transabdominal approach.  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