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   2464391篇
  免费   180574篇
  国内免费   3710篇
耳鼻咽喉   33853篇
儿科学   79491篇
妇产科学   66210篇
基础医学   364306篇
口腔科学   67360篇
临床医学   219608篇
内科学   482948篇
皮肤病学   55721篇
神经病学   195242篇
特种医学   90610篇
外国民族医学   518篇
外科学   368379篇
综合类   48126篇
现状与发展   12篇
一般理论   880篇
预防医学   195508篇
眼科学   56756篇
药学   183802篇
  9篇
中国医学   4932篇
肿瘤学   134404篇
  2021年   21944篇
  2019年   22451篇
  2018年   30888篇
  2017年   22825篇
  2016年   25195篇
  2015年   28314篇
  2014年   39690篇
  2013年   59215篇
  2012年   82686篇
  2011年   87525篇
  2010年   51536篇
  2009年   48387篇
  2008年   81091篇
  2007年   86217篇
  2006年   86908篇
  2005年   84281篇
  2004年   80408篇
  2003年   77224篇
  2002年   74668篇
  2001年   111266篇
  2000年   114036篇
  1999年   95679篇
  1998年   27831篇
  1997年   24264篇
  1996年   24620篇
  1995年   23180篇
  1994年   21294篇
  1993年   20080篇
  1992年   73186篇
  1991年   71244篇
  1990年   69488篇
  1989年   66664篇
  1988年   61216篇
  1987年   60047篇
  1986年   56101篇
  1985年   53831篇
  1984年   39991篇
  1983年   33987篇
  1982年   20227篇
  1979年   36538篇
  1978年   26122篇
  1977年   21614篇
  1976年   20732篇
  1975年   22272篇
  1974年   26778篇
  1973年   25439篇
  1972年   23756篇
  1971年   22544篇
  1970年   20821篇
  1969年   19833篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
BackgroundSecond-hand smoking or environmental tobacco smoke is a critical health risk. Children are the most vulnerable to second-hand smoking because of their small bronchial ducts, less developed immunity, and low-physical activity.ObjectivesThe purpose of this study was to ascertain the effects of second-hand smoking on lung functions in athlete and non-athlete school-aged children.MethodsThis observational study included forty-six school-aged children, their age was 8–15 years, assigned to three groups; 2 study groups and 1 control group (n=15). The study groups comprised of 16 football players, and of 15 cyclists. Lung functions were evaluated recording forced vital capacity, forced expiratory volume in 1 sec and peak expiratory flow using digital spirometer.ResultsAll measures were recorded in definite values and the children were also classified into second-hand smoking (SH), or non-exposed to tobacco smoking (NE). The findings presented a significant increase (p<0.05) of the study groups in forced vital capacity, forced expiratory volume in 1 sec and peak expiratory flow solely for the non-exposed children. However, there were non-significant differences between the cyclists and football players or between the passive smoking children and non-exposed children in any of the two study groups (p>0.05).ConclusionThe outcomes of this study suggest beneficial influences of the sports activity on the lung functions, without different influences of the cyclists and football players on the lung functions.  相似文献   
102.
103.
104.
105.
106.
107.
108.
109.
The present study aimed at measuring seropositivities for infection by Ascaris suum and Toxocara canis using the excretory/secretory (E/S) antigens from Ascaris suum (AES) and Toxocara canis (TES) within an indigenous population. In addition, quantification of cytokine expressions in peripheral blood cells was determined. A total of 50 Warao indigenous were included; of which 43 were adults and seven children. In adults, 44.1% were seropositive for both parasites; whereas children had only seropositivity to one or the other helminth. For ascariosis, the percentage of AES seropositivity in adults and children was high; 23.3% and 57.1%, respectively. While that for toxocariosis, the percentage of TES seropositivity in adults and children was low; 9.3% and 14.3%, respectively. The percentage of seronegativity was comparable for AES and TES antigens in adults (27.9%) and children (28.6%). When positive sera were analyzed by Western blotting technique using AES antigens; three bands of 97.2, 193.6 and 200.2 kDas were mostly recognized. When the TES antigens were used, nine major bands were mostly identified; 47.4, 52.2, 84.9, 98.2, 119.1, 131.3, 175.6, 184.4 and 193.6 kDas. Stool examinations showed that Blastocystis hominis, Hymenolepis nana and Entamoeba coli were the most commonly observed intestinal parasites. Quantification of cytokines IFN-γ, IL-2, IL-6, TGF-β, TNF-α, IL-10 and IL-4 expressions showed that there was only a significant increased expression of IL-4 in indigenous with TES seropositivity (p < 0.002). Ascaris and Toxocara seropositivity was prevalent among Warao indigenous.  相似文献   
110.
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