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   2094000篇
  免费   145724篇
  国内免费   4663篇
耳鼻咽喉   28553篇
儿科学   68005篇
妇产科学   59356篇
基础医学   295423篇
口腔科学   56885篇
临床医学   183368篇
内科学   413970篇
皮肤病学   47063篇
神经病学   170318篇
特种医学   80517篇
外国民族医学   772篇
外科学   316498篇
综合类   47739篇
现状与发展   3篇
一般理论   702篇
预防医学   160571篇
眼科学   47568篇
药学   147427篇
  46篇
中国医学   4559篇
肿瘤学   115044篇
  2019年   16795篇
  2018年   22915篇
  2017年   17735篇
  2016年   19595篇
  2015年   22013篇
  2014年   31333篇
  2013年   47158篇
  2012年   63756篇
  2011年   67742篇
  2010年   40195篇
  2009年   38343篇
  2008年   63296篇
  2007年   67056篇
  2006年   67653篇
  2005年   65999篇
  2004年   63203篇
  2003年   60545篇
  2002年   58799篇
  2001年   100322篇
  2000年   102848篇
  1999年   86140篇
  1998年   24175篇
  1997年   21976篇
  1996年   22001篇
  1995年   20657篇
  1994年   19014篇
  1993年   17907篇
  1992年   65668篇
  1991年   62730篇
  1990年   60734篇
  1989年   58070篇
  1988年   53598篇
  1987年   52473篇
  1986年   49532篇
  1985年   47263篇
  1984年   35794篇
  1983年   30390篇
  1982年   18384篇
  1981年   16210篇
  1979年   32169篇
  1978年   22619篇
  1977年   18902篇
  1976年   17901篇
  1975年   18975篇
  1974年   22822篇
  1973年   21967篇
  1972年   20631篇
  1971年   18888篇
  1970年   18080篇
  1969年   16861篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
At the time of hire, 4059 of 6522 healthcare workers required a 2-step tuberculin skin test; 114 workers (2.8%) demonstrated a boosted reaction after the second step. Boosted reactions were significantly associated with male sex and older age. A verbal history of previous tuberculin skin test results was not a reliable indicator of baseline tuberculin skin test status at the time of hire.  相似文献   
82.
Consecutive patients (n = 215) who were referred to optometric (55%) or multidisciplinary (45%) low-vision services and above 50 years of age were recruited from four hospitals in the Netherlands. They completed two vision-related quality of life questionnaires, the Vision Quality of Life Core Measure (VCM1) and the Low Vision Quality of Life Questionnaire (LVQOL), before their first visit with low-vision services and 1 year later. At follow-up, patients referred to multidisciplinary low-vision services had lower scores on the mobility subscale of the LVQOL than patients referred to optometric low-vision services [5.3 points; 95% confidence interval (CI): 0.2-10.5]. Paired sample t-tests for the two groups of patients taken together show improvement for the VCM1 (3.1 points; 95% CI: 0.6-5.6) and deterioration for the basic aspects of vision (3.5 points; 95% CI: 1.1-5.9) and the mobility (6.6 points; 95% CI: 3.7-9.5) subscales of the LVQOL. In conclusion, people referred to optometric services showed less deterioration in mobility than those referred to multidisciplinary services. No differences were observed for any of the other subscales of the LVQOL and the VCM1. Future research in this field should include randomized controlled designs comparing low-vision services with no treatment or placebo.  相似文献   
83.
This prospective clinic-based study evaluated the pretreatment periodontal status of the orthodontic patients seen at the University College Hospital, Ibadan, Nigeria, and assessed the relationship between dental aesthetic index (DAI) scores and periodontal status according to community periodontal index of treatment needs (CPITN) scores. One hundred forty five patients-70 (48.3%) males and 75 (51.7%) females from 6 to 45 years (mean 15.8 +/- 7.5)-were seen. World Health Organization (WHO) guidelines were followed in the examination and reporting of the periodontal status, and DAI scores were assessed based on WHO guidelines. The chi-square test was used to determine the association between the DAI and the CPITN scores. Most patients were in the 6-15 (55.9%) or 16-25 (35.9%) age groups. Based on the WHO preferred cumulative calculations of treatment need (TN), 35.2% of the patients had TN 0, 64.9% had TN 1, 24.9% had TN 2, and only 0.7% had TN 3. The relationship between DAI scores and periodontal treatment needs was not statistically significant (P >.05). Although many patients were yet to attain the WHO goal of no more than 1 sextant affected by bleeding or calculus at the age of 15, over one third had satisfactory periodontal health.  相似文献   
84.
85.
Four clinical trials of porcine islet transplantation have been reported, and there are verbal reports that clinical trials on much larger scales are continuing in centers in China and Russia. The four reported trials are briefly reviewed and, in the light of the present status of experimental islet xenotransplantation, consideration is given to whether such trials are currently justified. The Ethics Committee of the International Xenotransplantation Association has (1) emphasized the need for encouraging studies in non-human primates before clinical trials should be undertaken, (2) mandatory monitoring for the transfer of porcine microorganisms, and (3) careful regulation and oversight by recognized bodies. Other aspects of the topic, such as the need for informed consent, are briefly discussed. We conclude that, at the present time, more data documenting convincing efficacy, focused on clinically applicable immunosuppressive regimens, are needed to justify the initiation of closely monitored clinical trials. A clinical trial may then be justified even though the potential risk to the patients, and possibly for society, will not be zero.  相似文献   
86.
Spinocerebellar ataxia (SCA) types 2 and 3 are autosomal-dominant neurodegenerative disorders caused by mutations in two different genes. We identified mutations for SCA2 and SCA3 segregating simultaneously in a single Brazilian family. The index patient had SCA2, whereas her two second-degree cousins had SCA3. Disease was more rapidly progressive in the SCA2 patient, who presented severe brainstem and pancerebellar atrophy, as opposed to the two SCA3 patients, who had only mild cerebellar vermian atrophy. In such situations, molecular confirmation of all patients may avoid misdiagnosis of SCA subtypes and eventual errors in predictive testing of unaffected family members.  相似文献   
87.
88.
89.
90.
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