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   3147305篇
  免费   252073篇
  国内免费   5639篇
耳鼻咽喉   45744篇
儿科学   101331篇
妇产科学   85104篇
基础医学   445513篇
口腔科学   89852篇
临床医学   286273篇
内科学   613404篇
皮肤病学   65678篇
神经病学   260362篇
特种医学   125587篇
外国民族医学   1301篇
外科学   476353篇
综合类   74099篇
现状与发展   2篇
一般理论   1237篇
预防医学   252144篇
眼科学   73715篇
药学   235802篇
  6篇
中国医学   5945篇
肿瘤学   165565篇
  2018年   32460篇
  2017年   24866篇
  2016年   27432篇
  2015年   30975篇
  2014年   44305篇
  2013年   67576篇
  2012年   91753篇
  2011年   97095篇
  2010年   57385篇
  2009年   54838篇
  2008年   92246篇
  2007年   98356篇
  2006年   99014篇
  2005年   96329篇
  2004年   93226篇
  2003年   90225篇
  2002年   88680篇
  2001年   145975篇
  2000年   151165篇
  1999年   128141篇
  1998年   37089篇
  1997年   33622篇
  1996年   33481篇
  1995年   32297篇
  1994年   30268篇
  1993年   28271篇
  1992年   103082篇
  1991年   100177篇
  1990年   96793篇
  1989年   93194篇
  1988年   86305篇
  1987年   85040篇
  1986年   80259篇
  1985年   76781篇
  1984年   58220篇
  1983年   49551篇
  1982年   29823篇
  1981年   26753篇
  1979年   54235篇
  1978年   37982篇
  1977年   32139篇
  1976年   30201篇
  1975年   32101篇
  1974年   39137篇
  1973年   37294篇
  1972年   34770篇
  1971年   32001篇
  1970年   30298篇
  1969年   28034篇
  1968年   25529篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
111.
112.
The catechol-O-methyltransferase (COMT) enzyme is a major determinant of prefrontal dopamine levels. The Val158Met polymorphism affects COMT enzymatic activity and has been associated with variation in executive function and affective processing. This study investigated the effect of COMT genotype on the flexible modulation of the balance between processing self-generated and processing stimulus-oriented information, in the presence or absence of affective distractors. Analyses included 124 healthy adult participants, who were also assessed on standard working memory (WM) tasks. Relative to Val carriers, Met homozygotes made fewer errors when selecting and manipulating self-generated thoughts. This effect was partly accounted for by an association between COMT genotype and visuospatial WM performance. We also observed a complex interaction between the influence of affective distractors, COMT genotype and sex on task accuracy: male, but not female, participants showed a sensitivity to the affective distractors that was dependent on COMT genotype. This was not accounted for by WM performance. This study provides novel evidence of the role of dopaminergic genetic variation on the ability to select and manipulate self-generated thoughts. The results also suggest sexually dimorphic effects of COMT genotype on the influence of affective distractors on executive function.  相似文献   
113.
114.
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   
115.
116.
117.
The value of adding simeprevir (SMV) vs placebo (PBO) to peginterferon and ribavirin (PR) for treatment of chronic hepatitis C virus infection was examined using patient‐reported outcomes (PROs); further, concordance of PROs with virology endpoints and adverse events (AEs) was explored. Patients (= 768 SMV/PR,= 393 PBO/PR) rated fatigue (FSS), depressive symptoms (CES‐D) and functional impairment (WPAI: Hepatitis C Productivity, Daily Activity and Absenteeism) at baseline and throughout treatment in three randomised, double‐blind trials comparing the addition of SMV or PBO during initial 12 weeks of PR. PR was administered for 48 weeks (PBO group) and 24/48 weeks (SMV group) using a response‐guided therapy (RGT) approach. Mean PRO scores (except Absenteeism) worsened from baseline to Week 4 to the same extent in both groups but reverted after Week 24 for SMV/PR and only after Week 48 for PBO/PR. Accordingly, there was a significantly lower area under the curve (baseline–Week 60, AUC60) and fewer weeks with clinically important worsening of scores in the SMV/PR group at any time point. Incidences of patients with fatigue and anaemia AEs were similar in both groups, but FSS scores showed that clinically important increases in fatigue lasted a mean of 6.9 weeks longer with PBO/PR (P < 0.001). PRO score subgroup analysis indicated better outcomes for patients who met the criteria for RGT or achieved sustained virological response 12 weeks post‐treatment (SVR12); differences in mean PRO scores associated with fibrosis level were only observed with PBO/PR. Greater efficacy of SMV/PR enabled reduced treatment duration and reduced time with PR‐related AEs without adding to AE severity.  相似文献   
118.
119.
120.
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