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   930409篇
  免费   67647篇
  国内免费   1339篇
耳鼻咽喉   12980篇
儿科学   24358篇
妇产科学   23237篇
基础医学   133038篇
口腔科学   28237篇
临床医学   80480篇
内科学   183164篇
皮肤病学   19230篇
神经病学   72142篇
特种医学   36796篇
外国民族医学   79篇
外科学   152058篇
综合类   18038篇
现状与发展   1篇
一般理论   234篇
预防医学   61673篇
眼科学   21301篇
药学   72533篇
  3篇
中国医学   2162篇
肿瘤学   57651篇
  2018年   8962篇
  2017年   7033篇
  2016年   7761篇
  2015年   8862篇
  2014年   11990篇
  2013年   17499篇
  2012年   24088篇
  2011年   25042篇
  2010年   14812篇
  2009年   14269篇
  2008年   24612篇
  2007年   25697篇
  2006年   26490篇
  2005年   25431篇
  2004年   24562篇
  2003年   23612篇
  2002年   23162篇
  2001年   54737篇
  2000年   56554篇
  1999年   46967篇
  1998年   10738篇
  1997年   9475篇
  1996年   9602篇
  1995年   8940篇
  1994年   8290篇
  1993年   7602篇
  1992年   35501篇
  1991年   33926篇
  1990年   32750篇
  1989年   31879篇
  1988年   28999篇
  1987年   28264篇
  1986年   26300篇
  1985年   25154篇
  1984年   17842篇
  1983年   15146篇
  1982年   7802篇
  1981年   6777篇
  1979年   15789篇
  1978年   10608篇
  1977年   9055篇
  1976年   7877篇
  1975年   8630篇
  1974年   10472篇
  1973年   9859篇
  1972年   9358篇
  1971年   8856篇
  1970年   8426篇
  1969年   7923篇
  1968年   7202篇
排序方式: 共有10000条查询结果,搜索用时 286 毫秒
31.
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   
32.
33.
34.
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   
35.
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   
36.
37.
Objective: Polyunsaturated fatty acids n-3 (PUFA n-3) have shown effects in reducing tumor growth, in particular eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) abundantly present in fish oil (FO). When these fatty acids are provided in the diet, they alter the functions of the cells, particularly in tumor and immune cells. However, the effects of α-linolenic fatty acid (ALA), which is the precursor of EPA and DHA, are controversial. Thus, our objective was to test the effect of this parental fatty acid. Methods: Non-tumor-bearing and tumor-bearing Wistar rats (70 days) were supplemented with 1 g/kg body weight of FO or Oro Inca® (OI) oil (rich in ALA). Immune cells function, proliferation, cytokine production, and subpopulation profile were evaluated. Results: We have shown that innate immune cells enhanced phagocytosis capacity, and increased processing and elimination of antigens. Moreover, there was a decrease in production of pro-inflammatory cytokines (tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6)) by macrophages. Lymphocytes showed decreased proliferation capacity, increased cluster of differentiation 8 (CD8+) subpopulation, and increased TNF-α production. Conclusions: Oil rich in ALA caused similar immune modulation in cancer when compared with FO.  相似文献   
38.
39.
40.
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