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   1877031篇
  免费   130788篇
  国内免费   2652篇
耳鼻咽喉   26945篇
儿科学   57757篇
妇产科学   49169篇
基础医学   270542篇
口腔科学   54989篇
临床医学   166942篇
内科学   355970篇
皮肤病学   41881篇
神经病学   147277篇
特种医学   73526篇
外国民族医学   276篇
外科学   289705篇
综合类   37032篇
现状与发展   2篇
一般理论   509篇
预防医学   130965篇
眼科学   44243篇
药学   147816篇
  10篇
中国医学   4549篇
肿瘤学   110366篇
  2019年   13537篇
  2018年   20438篇
  2017年   16157篇
  2016年   18479篇
  2015年   20103篇
  2014年   26886篇
  2013年   40182篇
  2012年   54924篇
  2011年   58336篇
  2010年   34126篇
  2009年   31379篇
  2008年   55433篇
  2007年   58751篇
  2006年   59395篇
  2005年   57063篇
  2004年   54732篇
  2003年   52749篇
  2002年   51126篇
  2001年   99722篇
  2000年   103271篇
  1999年   85006篇
  1998年   21511篇
  1997年   18938篇
  1996年   18824篇
  1995年   17652篇
  1994年   16169篇
  1993年   15164篇
  1992年   63330篇
  1991年   60936篇
  1990年   59454篇
  1989年   57314篇
  1988年   52195篇
  1987年   50847篇
  1986年   47625篇
  1985年   45609篇
  1984年   33167篇
  1983年   27975篇
  1982年   15402篇
  1979年   29800篇
  1978年   20298篇
  1977年   17797篇
  1976年   15590篇
  1975年   17479篇
  1974年   20571篇
  1973年   19741篇
  1972年   18769篇
  1971年   17647篇
  1970年   16517篇
  1969年   15631篇
  1968年   14166篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
71.
72.
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   
73.
74.
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   
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.
79.
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   
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