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   2727932篇
  免费   190651篇
  国内免费   8090篇
耳鼻咽喉   36682篇
儿科学   90061篇
妇产科学   75020篇
基础医学   383250篇
口腔科学   74810篇
临床医学   245282篇
内科学   542086篇
皮肤病学   65897篇
神经病学   226278篇
特种医学   106689篇
外国民族医学   752篇
外科学   408532篇
综合类   51322篇
现状与发展   5篇
一般理论   994篇
预防医学   203149篇
眼科学   60459篇
药学   197493篇
  8篇
中国医学   5668篇
肿瘤学   152236篇
  2021年   22175篇
  2019年   22566篇
  2018年   32336篇
  2017年   25005篇
  2016年   29328篇
  2015年   32870篇
  2014年   44301篇
  2013年   65696篇
  2012年   88178篇
  2011年   92171篇
  2010年   55503篇
  2009年   52941篇
  2008年   86089篇
  2007年   91639篇
  2006年   93215篇
  2005年   89519篇
  2004年   85951篇
  2003年   83081篇
  2002年   80042篇
  2001年   131403篇
  2000年   134233篇
  1999年   113229篇
  1998年   32498篇
  1997年   28913篇
  1996年   28991篇
  1995年   28096篇
  1994年   25684篇
  1993年   23990篇
  1992年   86452篇
  1991年   82838篇
  1990年   80084篇
  1989年   77278篇
  1988年   70594篇
  1987年   69044篇
  1986年   64571篇
  1985年   61513篇
  1984年   45738篇
  1983年   38632篇
  1982年   22964篇
  1981年   20437篇
  1979年   39885篇
  1978年   28114篇
  1977年   23808篇
  1976年   21998篇
  1975年   23554篇
  1974年   27542篇
  1973年   26076篇
  1972年   24446篇
  1971年   22632篇
  1970年   20786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