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   930478篇
  免费   67592篇
  国内免费   1343篇
耳鼻咽喉   12954篇
儿科学   24368篇
妇产科学   23251篇
基础医学   132882篇
口腔科学   28249篇
临床医学   80472篇
内科学   183161篇
皮肤病学   19226篇
神经病学   72150篇
特种医学   36817篇
外国民族医学   79篇
外科学   152166篇
综合类   18038篇
现状与发展   1篇
一般理论   234篇
预防医学   61658篇
眼科学   21302篇
药学   72546篇
  3篇
中国医学   2163篇
肿瘤学   57693篇
  2018年   8970篇
  2017年   7027篇
  2016年   7770篇
  2015年   8868篇
  2014年   11989篇
  2013年   17498篇
  2012年   24102篇
  2011年   25053篇
  2010年   14814篇
  2009年   14270篇
  2008年   24614篇
  2007年   25710篇
  2006年   26503篇
  2005年   25448篇
  2004年   24588篇
  2003年   23625篇
  2002年   23171篇
  2001年   54729篇
  2000年   56549篇
  1999年   46958篇
  1998年   10734篇
  1997年   9468篇
  1996年   9599篇
  1995年   8929篇
  1994年   8285篇
  1993年   7596篇
  1992年   35507篇
  1991年   33932篇
  1990年   32741篇
  1989年   31882篇
  1988年   29002篇
  1987年   28256篇
  1986年   26297篇
  1985年   25145篇
  1984年   17833篇
  1983年   15143篇
  1982年   7796篇
  1981年   6771篇
  1979年   15782篇
  1978年   10600篇
  1977年   9057篇
  1976年   7871篇
  1975年   8629篇
  1974年   10470篇
  1973年   9858篇
  1972年   9358篇
  1971年   8854篇
  1970年   8426篇
  1969年   7925篇
  1968年   7208篇
排序方式: 共有10000条查询结果,搜索用时 15 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