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   2217700篇
  免费   170304篇
  国内免费   7357篇
耳鼻咽喉   29714篇
儿科学   71167篇
妇产科学   59985篇
基础医学   308501篇
口腔科学   62005篇
临床医学   199419篇
内科学   440610篇
皮肤病学   52279篇
神经病学   177056篇
特种医学   90397篇
外国民族医学   472篇
外科学   343516篇
综合类   49364篇
现状与发展   3篇
一般理论   656篇
预防医学   168640篇
眼科学   48751篇
药学   165058篇
  10篇
中国医学   4553篇
肿瘤学   123205篇
  2018年   22475篇
  2017年   17779篇
  2016年   20951篇
  2015年   23326篇
  2014年   32243篇
  2013年   47901篇
  2012年   61202篇
  2011年   65363篇
  2010年   39936篇
  2009年   38487篇
  2008年   61025篇
  2007年   65155篇
  2006年   66608篇
  2005年   63925篇
  2004年   61192篇
  2003年   59369篇
  2002年   56888篇
  2001年   112367篇
  2000年   115731篇
  1999年   96613篇
  1998年   26867篇
  1997年   23892篇
  1996年   24668篇
  1995年   24265篇
  1994年   22440篇
  1993年   21133篇
  1992年   77183篇
  1991年   74838篇
  1990年   72651篇
  1989年   69731篇
  1988年   63916篇
  1987年   62623篇
  1986年   59046篇
  1985年   56430篇
  1984年   42065篇
  1983年   35393篇
  1982年   21070篇
  1981年   18652篇
  1980年   17652篇
  1979年   37823篇
  1978年   26599篇
  1977年   23010篇
  1976年   20654篇
  1975年   22317篇
  1974年   26105篇
  1973年   25093篇
  1972年   23493篇
  1971年   21840篇
  1970年   20007篇
  1969年   18996篇
排序方式: 共有10000条查询结果,搜索用时 177 毫秒
81.
82.
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   
83.
84.
85.
As millions of people turn to social media for health information, better understanding the factors that guide health-related judgments and perceptions in this context is imperative. We report on two Web experiments (n > 400 total) examining the power of society’s widespread weight bias and related stereotypes to influence nutrition judgments in social media spaces. In Experiment 1, meals were judged as lower in nutritional quality when the person who recommended them (the source) was depicted as obese rather than of normal weight, an effect mediated by stereotypic beliefs about the source as a generally unhealthy person. Experiment 2 replicated this effect, which—notably—remained significant when controlling for objective nutritional information (calories and fat content). Results highlight spillover effects of weight bias that extend beyond person perception to color impressions of objects (here, food) that are associated with stigmatized attributes. Implications for everyday nutrition judgments and public health are considered.  相似文献   
86.
87.
88.
89.
Preimplantation genetic diagnosis (PGD) was originally developed to diagnose embryo-related genetic abnormalities for couples who present a high risk of a specific inherited disorder. Because this technology involves embryo selection, the medical, bioethical, and legal implications of the technique have been debated, particularly when it is used to select features that are not related to serious diseases. Although several initiatives have attempted to achieve regulatory harmonization, the diversity of healthcare services available and the presence of cultural differences have hampered attempts to achieve this goal. Thus, in different countries, the provision of PGD and regulatory frameworks reflect the perceptions of scientific groups, legislators, and society regarding this technology. In Brazil, several texts have been analyzed by the National Congress to regulate the use of assisted reproduction technologies. Legislative debates, however, are not conclusive, and limited information has been published on how PGD is specifically regulated. The country requires the development of new regulatory standards to ensure adequate access to this technology and to guarantee its safe practice. This study examined official documents published on PGD regulation in Brazil and demonstrated how little direct oversight of PGD currently exists. It provides relevant information to encourage reflection on a particular regulation model in a Brazilian context, and should serve as part of the basis to enable further reform of the clinical practice of PGD in the country.  相似文献   
90.
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