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   1291780篇
  免费   100717篇
  国内免费   2045篇
耳鼻咽喉   18692篇
儿科学   44649篇
妇产科学   35262篇
基础医学   184307篇
口腔科学   35312篇
临床医学   112428篇
内科学   261211篇
皮肤病学   28384篇
神经病学   101489篇
特种医学   51505篇
外国民族医学   660篇
外科学   197975篇
综合类   27082篇
现状与发展   1篇
一般理论   380篇
预防医学   97614篇
眼科学   28063篇
药学   95892篇
  2篇
中国医学   2576篇
肿瘤学   71058篇
  2019年   9624篇
  2018年   13774篇
  2017年   10454篇
  2016年   11361篇
  2015年   13008篇
  2014年   17938篇
  2013年   27128篇
  2012年   37368篇
  2011年   39573篇
  2010年   23571篇
  2009年   22393篇
  2008年   37605篇
  2007年   40204篇
  2006年   40281篇
  2005年   39131篇
  2004年   38127篇
  2003年   36918篇
  2002年   36186篇
  2001年   64174篇
  2000年   66675篇
  1999年   56547篇
  1998年   15179篇
  1997年   13798篇
  1996年   14222篇
  1995年   13480篇
  1994年   12799篇
  1993年   11810篇
  1992年   44606篇
  1991年   43529篇
  1990年   42253篇
  1989年   40154篇
  1988年   36926篇
  1987年   36258篇
  1986年   33647篇
  1985年   32308篇
  1984年   24153篇
  1983年   20289篇
  1982年   11731篇
  1981年   10702篇
  1979年   21362篇
  1978年   14833篇
  1977年   12545篇
  1976年   11698篇
  1975年   12632篇
  1974年   14667篇
  1973年   14136篇
  1972年   12951篇
  1971年   11740篇
  1970年   11059篇
  1969年   10039篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
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   
53.
54.
55.
56.
57.
Advancement in microelectromechanical system has facilitated the microfabrication of polymeric substrates and the development of the novel class of controlled drug delivery devices. These vehicles have specifically tailored three dimensional physical and chemical features which together, provide the capacity to target cell, stimulate unidirectional controlled release of therapeutics and augment permeation across the barriers. Apart from drug delivery devices microfabrication technology’s offer exciting prospects to generate biomimetic gastrointestinal tract models. BioMEMS are capable of analysing biochemical liquid sample like solution of metabolites, macromolecules, proteins, nucleic acid, cells and viruses. This review summarized multidisciplinary application of biomedical microelectromechanical systems in drug delivery and its potential in analytical procedures.  相似文献   
58.
59.
In the 6th Basic Plan for Long-Term Electricity Supply and Demand (6th BPE) for Korea, for the first time, the environmental costs of air pollution caused by oxides of sulfur (SOx), oxides of nitrogen (NOx), and particulate matters (PM) from power plants were estimated and included. However, several deficiencies in evaluating the environmental costs were found. In this study, (1) the validity of the environmental costs used in the 6th BPE was assessed, (2) a systematic approach was suggested and used to improve the environmental costs estimation, and (3) the sensitivity of the cost of generating electricity to the environmental costs by fuel type with the proposed approach was discussed. We found that the applied environmental costs used in the 6th BPE did not fully include the demographic characteristics of Korea. By applying more realistic parameter values, it was found that the newly estimated environmental cost was about 23 times higher than the cost estimated in the original 6th BPE for coal-fired power plants and about 1.5 times higher for liquefied natural gas (LNG)-fired power plants, suggesting that LNG-fired power plants are more economical if using more realistic environmental costs. Thus, it is critical to check the validity of parameter values when calculating environmental costs.  相似文献   
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