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   1713419篇
  免费   131193篇
  国内免费   5550篇
耳鼻咽喉   22669篇
儿科学   52929篇
妇产科学   48702篇
基础医学   241810篇
口腔科学   47770篇
临床医学   150139篇
内科学   345991篇
皮肤病学   39973篇
神经病学   138516篇
特种医学   64938篇
外国民族医学   527篇
外科学   259940篇
综合类   40277篇
现状与发展   3篇
一般理论   537篇
预防医学   123816篇
眼科学   39129篇
药学   123779篇
  2篇
中国医学   4910篇
肿瘤学   103805篇
  2021年   12804篇
  2019年   13633篇
  2018年   19839篇
  2017年   15082篇
  2016年   16769篇
  2015年   18874篇
  2014年   26677篇
  2013年   38860篇
  2012年   52731篇
  2011年   55396篇
  2010年   32686篇
  2009年   31303篇
  2008年   51256篇
  2007年   54510篇
  2006年   55025篇
  2005年   52729篇
  2004年   50297篇
  2003年   48091篇
  2002年   46353篇
  2001年   94257篇
  2000年   96575篇
  1999年   80017篇
  1998年   21196篇
  1997年   18752篇
  1996年   18514篇
  1995年   17473篇
  1994年   15820篇
  1993年   14748篇
  1992年   58993篇
  1991年   55729篇
  1990年   53325篇
  1989年   51397篇
  1988年   46901篇
  1987年   45571篇
  1986年   42325篇
  1985年   40161篇
  1984年   29804篇
  1983年   24842篇
  1982年   14482篇
  1981年   12660篇
  1979年   25516篇
  1978年   17503篇
  1977年   14720篇
  1976年   13332篇
  1975年   13954篇
  1974年   16704篇
  1973年   16074篇
  1972年   15171篇
  1971年   13928篇
  1970年   13167篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
93.
Liposarcomas are extremely rare in the mediastinum. They may achieve considerable size before causing any symptoms. Mediastinal liposarcomas may invade surrounding structures like the pericardium or the superior vena cava. Complete surgical excision is the optimal treatment in resectable cases. Excision of adjacent structures like the pericardium may be needed if the tumor infiltrates them. We report on a case of a giant liposarcoma of the mediastinum involving both hemithoraces and extending into the neck, which was successfully managed by complete surgical excision.  相似文献   
94.
95.
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   
96.
BACKGROUND: An augmented reality tool for computer assisted surgery named X-Scope allows visual tracking of real anatomical structures in superposition with volume rendered CT or MRI scans and thus can be used for navigated translocation of bony segments. METHODS: In a feasibility study X-Scope was used in orthognathic surgery to control the translocation of the maxilla after Le Fort I osteotomy within a bimaxillary procedure. The situation achieved was compared with the pre-operative situation by means of cephalometric analysis on lateral and frontal cephalograms. RESULTS: The technique was successfully utilized in 5 patients. Maxillary positioning using X-Scope was accomplished accurately within a range of 1mm. The tool was used in all cases in addition to the usual intra-operative splints. A stand-alone application without conventional control does not yet seem reasonable. CONCLUSION: Augmented reality tools like X-Scope may be helpful for controlling maxillary translocation in orthognathic surgery. The application to other interventions in cranio-maxillofacial surgery such as Le Fort III osteotomy, fronto-orbital advancement, and cranial vault reshaping or repair may also be considered.  相似文献   
97.
98.
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   
99.
100.
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   
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