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   2459969篇
  免费   181274篇
  国内免费   3686篇
耳鼻咽喉   33770篇
儿科学   79667篇
妇产科学   65201篇
基础医学   362909篇
口腔科学   69743篇
临床医学   219823篇
内科学   481153篇
皮肤病学   54751篇
神经病学   194848篇
特种医学   91449篇
外国民族医学   508篇
外科学   367960篇
综合类   48539篇
现状与发展   12篇
一般理论   892篇
预防医学   195275篇
眼科学   56680篇
药学   181828篇
  10篇
中国医学   5062篇
肿瘤学   134849篇
  2021年   21813篇
  2019年   22083篇
  2018年   30650篇
  2017年   23027篇
  2016年   25196篇
  2015年   28543篇
  2014年   40165篇
  2013年   58953篇
  2012年   82490篇
  2011年   87722篇
  2010年   51269篇
  2009年   48159篇
  2008年   80746篇
  2007年   86102篇
  2006年   86316篇
  2005年   84041篇
  2004年   80222篇
  2003年   76934篇
  2002年   73161篇
  2001年   111083篇
  2000年   113656篇
  1999年   95541篇
  1998年   27933篇
  1997年   24457篇
  1996年   24797篇
  1995年   23393篇
  1994年   21528篇
  1993年   20349篇
  1992年   73337篇
  1991年   71406篇
  1990年   69642篇
  1989年   66905篇
  1988年   61459篇
  1987年   60201篇
  1986年   56245篇
  1985年   53989篇
  1984年   40034篇
  1983年   33998篇
  1982年   20221篇
  1979年   36407篇
  1978年   26000篇
  1977年   21527篇
  1976年   20605篇
  1975年   22162篇
  1974年   26494篇
  1973年   25148篇
  1972年   23490篇
  1971年   22307篇
  1970年   20536篇
  1969年   19582篇
排序方式: 共有10000条查询结果,搜索用时 31 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