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   1799000篇
  免费   129103篇
  国内免费   3925篇
耳鼻咽喉   23500篇
儿科学   60014篇
妇产科学   49611篇
基础医学   255218篇
口腔科学   51218篇
临床医学   159805篇
内科学   352241篇
皮肤病学   41543篇
神经病学   139416篇
特种医学   68424篇
外国民族医学   273篇
外科学   274316篇
综合类   40421篇
现状与发展   4篇
一般理论   569篇
预防医学   130282篇
眼科学   43074篇
药学   130793篇
  7篇
中国医学   4717篇
肿瘤学   106582篇
  2021年   13846篇
  2019年   14543篇
  2018年   21311篇
  2017年   16179篇
  2016年   17783篇
  2015年   20308篇
  2014年   28038篇
  2013年   40771篇
  2012年   56143篇
  2011年   58843篇
  2010年   34884篇
  2009年   32612篇
  2008年   54599篇
  2007年   58061篇
  2006年   58518篇
  2005年   55873篇
  2004年   53976篇
  2003年   51215篇
  2002年   49400篇
  2001年   96718篇
  2000年   98627篇
  1999年   81282篇
  1998年   21061篇
  1997年   18568篇
  1996年   18449篇
  1995年   17712篇
  1994年   16180篇
  1993年   14963篇
  1992年   60353篇
  1991年   58054篇
  1990年   55782篇
  1989年   53489篇
  1988年   48613篇
  1987年   47331篇
  1986年   44607篇
  1985年   42200篇
  1984年   30993篇
  1983年   26287篇
  1982年   14752篇
  1979年   27154篇
  1978年   18773篇
  1977年   15875篇
  1976年   14717篇
  1975年   15650篇
  1974年   18722篇
  1973年   18016篇
  1972年   16601篇
  1971年   15346篇
  1970年   14265篇
  1969年   13240篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
63.
64.
65.
BACKGROUND: The aim of this study was to estimate the cost effectiveness of screening for abdominal aortic aneurysm (AAA). MATERIAL AND METHODS: All 12,639 men born in the years 1921-1933 (aged 64-73) living in Viborg County, Denmark, were randomly allocated either to receive an invitation to abdominal ultrasound scanning for AAA or to be controls. Costs for screening and surveillance were assessed prospectively. Diagnosis Related Group (DRG) costs from 1999 were used concerning admissions with uncomplicated and complicated operations. Admissions for AAA surgery were retrospectively classified according to complications in patient records. RESULTS: Mean follow-up time was 52 months. 76.6% of invited men attended screening, and 191 (4.0%) had an AAA. As previously reported, the cumulative 5-year AAA-specific mortality in the invited group was significantly reduced by 67% compared to the control group (P = 0.003). The costs were estimated to be Euro 11.23 per scan. The costs per life-year saved were Euro 9057 (Euro 5872-20,063) after 5 years, and were expected to decrease to Euro 2708 (Euro 1758-6031) after 10 years and to Euro 1825 (Euro 1185-4063) after 15 years. CONCLUSION: Screening of 64-73 years old males in Denmark seems cost effective.  相似文献   
66.
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   

67.
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   
68.
69.
70.
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