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   2564858篇
  免费   176485篇
  国内免费   5086篇
耳鼻咽喉   34970篇
儿科学   84156篇
妇产科学   69678篇
基础医学   365804篇
口腔科学   74383篇
临床医学   230178篇
内科学   490163篇
皮肤病学   59032篇
神经病学   200607篇
特种医学   99386篇
外国民族医学   460篇
外科学   388183篇
综合类   54735篇
现状与发展   5篇
一般理论   787篇
预防医学   185524篇
眼科学   60966篇
药学   193387篇
  13篇
中国医学   6432篇
肿瘤学   147580篇
  2021年   19177篇
  2019年   19886篇
  2018年   29551篇
  2017年   22825篇
  2016年   25790篇
  2015年   29183篇
  2014年   39349篇
  2013年   57580篇
  2012年   80058篇
  2011年   83848篇
  2010年   49680篇
  2009年   45972篇
  2008年   77994篇
  2007年   83589篇
  2006年   84214篇
  2005年   81062篇
  2004年   77902篇
  2003年   74584篇
  2002年   71885篇
  2001年   131027篇
  2000年   133940篇
  1999年   111372篇
  1998年   29363篇
  1997年   25650篇
  1996年   25490篇
  1995年   24306篇
  1994年   22207篇
  1993年   20736篇
  1992年   83328篇
  1991年   80399篇
  1990年   78172篇
  1989年   75022篇
  1988年   68152篇
  1987年   66462篇
  1986年   62794篇
  1985年   59511篇
  1984年   43649篇
  1983年   37139篇
  1982年   20958篇
  1979年   39024篇
  1978年   26906篇
  1977年   23360篇
  1976年   21218篇
  1975年   23193篇
  1974年   27627篇
  1973年   26599篇
  1972年   24897篇
  1971年   23266篇
  1970年   21489篇
  1969年   20328篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
75.
76.
77.
78.
Pre-eclamptic toxaemia (PET) may be associated with both endothelial dysfunction (ED) and sleep-disordered breathing (SDB). It was hypothesised that females with PET would demonstrate both SDB and ED, and that a correlation between these two would suggest a potential causative association. A total of 17 females with PET and 25 matched females with uncomplicated pregnancy were studied. They underwent a nocturnal ambulatory sleep study (using Watch_PAT100) and noninvasive evaluation of endothelial function utilising the reactive hyperaemia test (using Endo_PAT 2000). A higher ratio of post- to pre-occlusion pulse-wave amplitude (endothelial function index (EFI)) indicated better endothelial function. Females with PET had a significantly higher respiratory disturbance index (RDI) and lower EFI than controls (18.4+/-8.4 versus 8.3+/-1.3.h(-1), and 1.5+/-0.1 versus 1.8+/-0.1, respectively). Blood pressure significantly correlated with RDI and with EFI. EFI tended to correlate with RDI. In conclusion, these results suggest that both sleep-disordered breathing and endothelial dysfunction are more likely to occur in females with pre-eclamptic toxaemia than in females with uncomplicated pregnancies. The current authors speculate that respiratory disturbances contribute to the functional abnormality of the blood vessels seen in females with pre-eclamptic toxaemia, although causality cannot be determined based on this study.  相似文献   
79.
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   
80.
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