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   2046879篇
  免费   148018篇
  国内免费   3118篇
耳鼻咽喉   29339篇
儿科学   62217篇
妇产科学   57272篇
基础医学   294986篇
口腔科学   59639篇
临床医学   175586篇
内科学   400386篇
皮肤病学   42733篇
神经病学   159330篇
特种医学   80389篇
外国民族医学   438篇
外科学   324241篇
综合类   41577篇
现状与发展   2篇
一般理论   510篇
预防医学   144365篇
眼科学   47285篇
药学   158180篇
  3篇
中国医学   4301篇
肿瘤学   115236篇
  2018年   19092篇
  2016年   16331篇
  2015年   18835篇
  2014年   25809篇
  2013年   38809篇
  2012年   53211篇
  2011年   56530篇
  2010年   33521篇
  2009年   31767篇
  2008年   55075篇
  2007年   59041篇
  2006年   60106篇
  2005年   58570篇
  2004年   56569篇
  2003年   54680篇
  2002年   53839篇
  2001年   102493篇
  2000年   105729篇
  1999年   89203篇
  1998年   23160篇
  1997年   20590篇
  1996年   20809篇
  1995年   19524篇
  1994年   18397篇
  1993年   17009篇
  1992年   70293篇
  1991年   68325篇
  1990年   66886篇
  1989年   65129篇
  1988年   60290篇
  1987年   58823篇
  1986年   55686篇
  1985年   53195篇
  1984年   38893篇
  1983年   33472篇
  1982年   18837篇
  1981年   16566篇
  1979年   35896篇
  1978年   24814篇
  1977年   21423篇
  1976年   19567篇
  1975年   21504篇
  1974年   25664篇
  1973年   24442篇
  1972年   23343篇
  1971年   21857篇
  1970年   20527篇
  1969年   19666篇
  1968年   18246篇
  1967年   16128篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
52.
53.
54.
55.
56.
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   
57.
58.
Past research suggests that as many as 50% of onward human immunodeficiency virus (HIV) transmissions occur during acute and recent HIV infection. It is clearly important to develop interventions which focus on this highly infectious stage of HIV infection to prevent further transmission in the risk networks of acutely and recently infected individuals. Project Protect tries to find recently and acutely infected individuals and prevents HIV transmission in their risk networks. Participants are recruited by community health outreach workers at community-based HIV testing sites and drug users' community venues, by coupon referrals and through referrals from AIDS clinics. When a network with acute/recent infection is identified, network members are interviewed about their risky behaviors, network information is collected, and blood is drawn for HIV testing. Participants are also educated and given prevention materials (condoms, syringes, educational materials); HIV-infected participants are referred to AIDS clinics and are assisted with access to care. Community alerts about elevated risk of HIV transmission are distributed within the risk networks of recently infected. Overall, 342 people were recruited to the project and screened for acute/recent HIV infection. Only six index cases of recent infection (2.3% of all people screened) were found through primary screening at voluntary counseling and testing (VCT) sites, but six cases of recent infection were found through contact tracing of these recently infected participants (7% of network members who came to the interview). Combining screening at VCT sites and contact tracing the number of recently infected people we located as compared to VCT screening alone. No adverse events were encountered. These first results provide evidence for the theory behind the intervention, i.e., in the risk networks of recently infected people there are other people with recent HIV infection and they can be successfully located without increasing stigma for project participants.  相似文献   
59.
60.
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