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   2043233篇
  免费   152475篇
  国内免费   3131篇
耳鼻咽喉   29556篇
儿科学   64051篇
妇产科学   54254篇
基础医学   290019篇
口腔科学   58005篇
临床医学   177933篇
内科学   405408篇
皮肤病学   43828篇
神经病学   159575篇
特种医学   81228篇
外国民族医学   725篇
外科学   322756篇
综合类   42071篇
现状与发展   2篇
一般理论   576篇
预防医学   146788篇
眼科学   45990篇
药学   155066篇
  5篇
中国医学   4206篇
肿瘤学   116797篇
  2018年   20146篇
  2017年   15467篇
  2016年   17094篇
  2015年   19328篇
  2014年   26741篇
  2013年   40271篇
  2012年   55115篇
  2011年   58076篇
  2010年   34720篇
  2009年   33185篇
  2008年   56215篇
  2007年   59836篇
  2006年   60686篇
  2005年   58803篇
  2004年   57341篇
  2003年   55443篇
  2002年   54450篇
  2001年   107529篇
  2000年   111598篇
  1999年   94222篇
  1998年   23891篇
  1997年   21351篇
  1996年   21793篇
  1995年   20506篇
  1994年   19223篇
  1993年   17766篇
  1992年   73332篇
  1991年   71158篇
  1990年   69065篇
  1989年   66545篇
  1988年   61024篇
  1987年   59768篇
  1986年   55735篇
  1985年   53489篇
  1984年   39172篇
  1983年   33044篇
  1982年   18256篇
  1981年   16326篇
  1979年   34909篇
  1978年   23834篇
  1977年   20415篇
  1976年   18409篇
  1975年   20111篇
  1974年   23812篇
  1973年   22726篇
  1972年   21210篇
  1971年   19676篇
  1970年   18636篇
  1969年   17158篇
  1968年   15559篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
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   
72.
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   
73.
74.
75.
76.
77.
The aim of the study was to determine the effect of β-glucan on the cytotoxicity and genotoxicity of polypectomized patient's fecal water (FW). Polypectomized volunteers (n = 69) were randomly assigned to consume bread with or without β-glucan, for 3 months. FW was collected at the beginning (t = 0), the 30th and 90th day and 2 wk after the intervention. Cytotoxicity and genotoxicity were estimated on Caco-2 cells, using trypan blue exclusion test and comet assay, respectively. Gastrointestinal symptoms were recorded and subjects kept a 3-day food diary at baseline and after completion. Trypan blue exclusion test revealed cell survival of approximately 87% after incubation with FW. The FW samples showed 49% genotoxicity at the baseline. Genotoxicity in the intervention group decreased during the trial reaching statistical significance on the 90th day compared to control. An increase was noticed 2 wk after the trial, but it still remained significantly lower compared to control. Group-specific analysis for β-glucan also revealed significant decrease in the genotoxicity on the 90th day compared to baseline. β-glucan ingestion in polypectomized patients significantly decreased the genotoxicity of their FW. Our findings suggest that β-glucan consumption could possibly provide protection against colon cancer development.  相似文献   
78.
Annals of Nuclear Medicine - The Response Evaluation Criteria In Solid Tumors (RECIST) is the most used radiological method for evaluating response after peptide receptor radionuclide therapy...  相似文献   
79.
80.
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