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   2006163篇
  免费   133184篇
  国内免费   4419篇
耳鼻咽喉   24179篇
儿科学   65362篇
妇产科学   51728篇
基础医学   277858篇
口腔科学   53370篇
临床医学   176224篇
内科学   392741篇
皮肤病学   42018篇
神经病学   160492篇
特种医学   78166篇
外国民族医学   248篇
外科学   307263篇
综合类   43204篇
现状与发展   6篇
一般理论   662篇
预防医学   151339篇
眼科学   45621篇
药学   142372篇
  9篇
中国医学   5319篇
肿瘤学   125585篇
  2021年   15157篇
  2019年   15896篇
  2018年   43967篇
  2017年   34328篇
  2016年   38819篇
  2015年   22874篇
  2014年   31273篇
  2013年   44567篇
  2012年   68099篇
  2011年   85108篇
  2010年   55943篇
  2009年   47164篇
  2008年   79876篇
  2007年   86838篇
  2006年   64865篇
  2005年   64396篇
  2004年   63594篇
  2003年   61987篇
  2002年   57675篇
  2001年   93475篇
  2000年   95271篇
  1999年   78590篇
  1998年   21891篇
  1997年   19067篇
  1996年   18815篇
  1995年   18053篇
  1994年   16480篇
  1993年   15218篇
  1992年   58170篇
  1991年   56130篇
  1990年   53693篇
  1989年   51394篇
  1988年   46744篇
  1987年   45557篇
  1986年   42755篇
  1985年   40535篇
  1984年   29972篇
  1983年   25481篇
  1982年   14688篇
  1981年   13038篇
  1979年   25946篇
  1978年   17977篇
  1977年   15297篇
  1976年   14248篇
  1975年   14837篇
  1974年   17903篇
  1973年   17150篇
  1972年   15846篇
  1971年   14572篇
  1970年   13600篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
62.
63.
64.
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   
65.
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   

66.
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   
67.
68.
The objective of this study is to test the luminous efficiency functions V(lambda), V'(lambda), V(10)(lambda) and their linear combinations on the basis of a data set gained from a simulated mesopic night-time driving experiment. Another aim is to provide 'real-world' data for the 'X framework' or 'linear combination model', and to find out its limits in a practical situation. Human performance was measured by the reaction time method. Results show that the single parameter of the linear combination of photopic and scotopic luminous efficiency functions can be determined analytically with little variation for a given mesopic background luminance level and a given visual target colour, but the computation leads to considerable deviations comparing all three target colours (red, green and blue) used in the experiment. The conclusion for the given experimental conditions is that the single parameter of the linear combination model has an increasing deviation for lower background luminance levels.  相似文献   
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