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   2721893篇
  免费   190416篇
  国内免费   7891篇
耳鼻咽喉   36615篇
儿科学   90264篇
妇产科学   75233篇
基础医学   382119篇
口腔科学   74291篇
临床医学   245091篇
内科学   539720篇
皮肤病学   66024篇
神经病学   225284篇
特种医学   106279篇
外国民族医学   752篇
外科学   407425篇
综合类   51360篇
现状与发展   5篇
一般理论   1006篇
预防医学   203607篇
眼科学   60554篇
药学   197428篇
  8篇
中国医学   5708篇
肿瘤学   151427篇
  2021年   21386篇
  2019年   22050篇
  2018年   32163篇
  2017年   24856篇
  2016年   29064篇
  2015年   32456篇
  2014年   43550篇
  2013年   65185篇
  2012年   87726篇
  2011年   92281篇
  2010年   55142篇
  2009年   52215篇
  2008年   86100篇
  2007年   91718篇
  2006年   93355篇
  2005年   89832篇
  2004年   86334篇
  2003年   83504篇
  2002年   80492篇
  2001年   131469篇
  2000年   134376篇
  1999年   113130篇
  1998年   32197篇
  1997年   28710篇
  1996年   28843篇
  1995年   27905篇
  1994年   25527篇
  1993年   23878篇
  1992年   86343篇
  1991年   82765篇
  1990年   80000篇
  1989年   77224篇
  1988年   70533篇
  1987年   68980篇
  1986年   64499篇
  1985年   61440篇
  1984年   45679篇
  1983年   38581篇
  1982年   22926篇
  1981年   20396篇
  1979年   39838篇
  1978年   28078篇
  1977年   23789篇
  1976年   21984篇
  1975年   23532篇
  1974年   27528篇
  1973年   26052篇
  1972年   24425篇
  1971年   22626篇
  1970年   20769篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
Bifid mandibular canal.   总被引:1,自引:0,他引:1  
PURPOSE: To determine the incidence and characteristics of bifid mandibular canals. METHODS: A retrospective study was performed using panoramic radiographs of 2012 patients subjected to dental treatment in the Dental Clinic of the Valencia University Dental School (Valencia, Spain) between 1996 and 1999. The goal was to investigate the presence of double mandibular canals. RESULTS: The extraoral panoramic radiographs revealed a total of 7 images suggestive of bifid canals. Mandibular computed tomography revealed the existence of this anatomic variant in 2 of 3 patients. An analysis was performed on the incidence of this type of image in extraoral panoramic radiography, its possible interpretations, and the clinical implications of bifid mandibular canals. CONCLUSIONS: In this study, 0.35% of canals were bifid. All cases were in women.  相似文献   
83.
84.
85.
86.
87.
88.
89.
The aim of this study was to determine whether patients with sickle cell disease (SCD) in steady state had pulmonary abnormalities seen on high-resolution computed tomography (HRCT) and whether any abnormalities correlated with contemporaneously diagnosed lung function abnormalities. A subsidiary question was whether the results of a noninvasive measure of haemolysis (end-tidal carbon monoxide (ETCO) levels) correlated with pulmonary function abnormalities. Thirty three patients with SCD, median (range) age 36 yrs (17-67 yrs) were examined. The degree of lobar volume loss and ground-glass opacification and prominence of central vessels on HRCT were quantitatively assessed. Pulmonary function was assessed by measurements of lung volumes, spirometry, gas transfer and oxygen saturation. ETCO levels were measured using an end-tidal CO monitor. Forced expiratory volume in one second (FEV1), forced vital capacity and total lung capacity significantly correlated with HRCT findings, particularly lobar volume loss. ETCO levels significantly negatively correlated with FEV1, vital capacity measured using a plethysmograph, specific airway conductance and arterial oxygen saturation measured by pulse oxymetry. In conclusion, the present results suggest that high-resolution computed tomography noninvasive assessment of haemolysis might be useful to identify sickle cell disease patients with respiratory function impairment.  相似文献   
90.
Accurate assessment of the amount and intensity of physical activity in daily life is considered very important due to the close relationship between physical activity level, health, disability and mortality. For this reason, assessment of physical activity in daily life has gained interest in recent years, especially in sedentary populations, such as patients with chronic obstructive pulmonary disease (COPD). The present article aims to compare and discuss the two kinds of instruments more commonly used to quantify the amount of physical activity performed by COPD patients in daily life: subjective methods (questionnaires, diaries) and motion sensors (electronic or mechanical methods). Their characteristics are summarised and evidence of their validity, reliability and sensitivity is discussed, when available. Subjective methods have practical value mainly in providing the patients' view on their performance in activities of daily living and functional status. However, care must be taken when using subjective methods to accurately quantify the amount of daily physical activity performed. More accurate information is likely to be available with motion sensors rather than questionnaires. The selection of which motion sensor to use for quantification of physical activity in daily life should depend mainly on the purpose of its use.  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