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   3433026篇
  免费   250852篇
  国内免费   9218篇
耳鼻咽喉   46447篇
儿科学   113259篇
妇产科学   95735篇
基础医学   481860篇
口腔科学   94762篇
临床医学   314701篇
内科学   674071篇
皮肤病学   81395篇
神经病学   282466篇
特种医学   130804篇
外国民族医学   1113篇
外科学   512577篇
综合类   74065篇
现状与发展   7篇
一般理论   1334篇
预防医学   267542篇
眼科学   77734篇
药学   248360篇
  8篇
中国医学   7251篇
肿瘤学   187605篇
  2019年   27467篇
  2018年   38520篇
  2017年   29570篇
  2016年   33967篇
  2015年   38251篇
  2014年   53307篇
  2013年   80034篇
  2012年   106778篇
  2011年   113277篇
  2010年   67876篇
  2009年   64786篇
  2008年   105288篇
  2007年   111727篇
  2006年   113582篇
  2005年   109279篇
  2004年   104790篇
  2003年   101043篇
  2002年   97631篇
  2001年   165427篇
  2000年   169478篇
  1999年   142517篇
  1998年   41221篇
  1997年   36701篇
  1996年   36728篇
  1995年   35516篇
  1994年   32425篇
  1993年   30340篇
  1992年   110026篇
  1991年   105614篇
  1990年   102332篇
  1989年   98580篇
  1988年   90427篇
  1987年   88595篇
  1986年   82981篇
  1985年   79407篇
  1984年   59547篇
  1983年   50473篇
  1982年   30175篇
  1981年   26902篇
  1979年   52627篇
  1978年   37246篇
  1977年   31392篇
  1976年   29242篇
  1975年   30836篇
  1974年   36715篇
  1973年   35099篇
  1972年   32986篇
  1971年   30505篇
  1970年   28354篇
  1969年   26994篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
Imaging     
  相似文献   
122.
123.
124.
125.
126.
127.
Background: Few studies have examined the use of ultrasound for sciatic nerve localization. The authors evaluated the usefulness of low-frequency ultrasound in identifying the sciatic nerve at three locations in the lower extremity and in guiding needle advancement to target before nerve stimulation.

Methods: In this prospective observational study, 15 volunteers underwent sciatic nerve examination using a curved ultrasound probe in the range of 2-5 MHz and a Philips-ATL 5000 unit (ATL Ultrasound, Bothell, WA) in the gluteal, infragluteal, and proximal thigh regions. Thereafter, an insulated block needle was advanced inline with the ultrasound beam to reach the nerve target, which was further confirmed by electrical stimulation. The quality of sciatic nerve images, ease of needle to nerve contact, threshold stimulating current, and resultant motor response were recorded.

Results: The sciatic nerve was successfully identified in the transverse view as a solitary predominantly hyperechoic structure on ultrasound in all of the three regions examined. The target nerve was visualized easily in 87% and localized within two needle attempts in all patients. Nerve stimulation was successful in 100% after two attempts with a threshold current of 0.42 +/- 0.12 (mean +/- SD) eliciting foot plantarflexion or dorsiflexion.  相似文献   

128.
Infections due to Penicillium species other than P.marneffei are rare. We identified a boy with X-linked chronic granulomatous disease (X-CGD) with a pulmonary nodule and adjacent rib osteomyelitis caused by Penicillium piceum. The only sign of infection was an elevated sedimentation rate. P. piceum was isolated by fine needle aspirate and from excised infected tissues. Surgical removal and one year of voriconazole treatment were very well tolerated and led to complete recovery. Microbiological, microscopic and molecular studies support the fungal diagnosis. P. piceum should be considered as a relevant pathogen in immunocompromised patients.  相似文献   
129.
130.
ABSTRACT: Background: Although increases in perinatal mortality risk associated with fetal macrosomia are well documented, the optimal route of delivery for fetuses with suspected macrosomia remains controversial. The objective of this investigation was to assess the risk of neonatal death among macrosomic infants delivered vaginally compared with those delivered by cesarean section. Methods: Data were derived from the U.S. 1995–1999 Linked Live Birth‐Infant Death Cohort files and term (37–44 wk), single live births to United States resident mothers selected. A proportional hazards model was used to analyze the risk of neonatal death associated with cesarean delivery among 3 categories of macrosomic infants (infants weighing 4,000–4,499 g; 4,500–4,999 g; and 5,000+ g). Results: After controlling for maternal characteristics and complications, the adjusted hazard ratio for neonatal death associated with cesarean delivery among the 3 categories of macrosomic infants was 1.40, 1.30, and 0.85. Conclusions: Although cesarean delivery may reduce the risk of death for the heaviest infants (5,000+ g), the relative benefit of this intervention for macrosomic infants weighing 4,000–4,999 g remains debatable. Thus, policies in support of prophylactic cesarean delivery for suspected fetal macrosomia may need to be reevaluated. (BIRTH 33:4 December 2006)  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