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   1286982篇
  免费   100745篇
  国内免费   2019篇
耳鼻咽喉   18484篇
儿科学   44786篇
妇产科学   35326篇
基础医学   183470篇
口腔科学   33872篇
临床医学   112346篇
内科学   260644篇
皮肤病学   28215篇
神经病学   101422篇
特种医学   51552篇
外国民族医学   666篇
外科学   197766篇
综合类   27230篇
现状与发展   1篇
一般理论   377篇
预防医学   96504篇
眼科学   28129篇
药学   95420篇
  2篇
中国医学   2423篇
肿瘤学   71111篇
  2018年   13327篇
  2017年   10111篇
  2016年   11035篇
  2015年   12541篇
  2014年   17413篇
  2013年   26554篇
  2012年   36543篇
  2011年   38602篇
  2010年   23076篇
  2009年   22066篇
  2008年   37086篇
  2007年   39751篇
  2006年   39976篇
  2005年   38926篇
  2004年   38104篇
  2003年   36888篇
  2002年   36207篇
  2001年   64314篇
  2000年   66783篇
  1999年   56685篇
  1998年   15226篇
  1997年   13841篇
  1996年   14287篇
  1995年   13527篇
  1994年   12867篇
  1993年   11869篇
  1992年   44793篇
  1991年   43697篇
  1990年   42443篇
  1989年   40330篇
  1988年   37065篇
  1987年   36435篇
  1986年   33815篇
  1985年   32475篇
  1984年   24299篇
  1983年   20393篇
  1982年   11805篇
  1981年   10763篇
  1980年   9582篇
  1979年   21510篇
  1978年   14933篇
  1977年   12646篇
  1976年   11788篇
  1975年   12741篇
  1974年   14800篇
  1973年   14236篇
  1972年   13071篇
  1971年   11827篇
  1970年   11142篇
  1969年   10093篇
排序方式: 共有10000条查询结果,搜索用时 765 毫秒
51.
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   
52.
53.
54.
55.
56.
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   
57.
58.
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   
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