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   1469746篇
  免费   118859篇
  国内免费   3468篇
耳鼻咽喉   18896篇
儿科学   48389篇
妇产科学   42671篇
基础医学   208651篇
口腔科学   38914篇
临床医学   135243篇
内科学   294679篇
皮肤病学   34087篇
神经病学   122587篇
特种医学   55567篇
外国民族医学   521篇
外科学   216633篇
综合类   33857篇
现状与发展   3篇
一般理论   584篇
预防医学   117621篇
眼科学   32542篇
药学   102479篇
  1篇
中国医学   3385篇
肿瘤学   84763篇
  2021年   11779篇
  2019年   12784篇
  2018年   17775篇
  2017年   13603篇
  2016年   15317篇
  2015年   17113篇
  2014年   24055篇
  2013年   35856篇
  2012年   48600篇
  2011年   51214篇
  2010年   30089篇
  2009年   28762篇
  2008年   47509篇
  2007年   50191篇
  2006年   50735篇
  2005年   49024篇
  2004年   46855篇
  2003年   44570篇
  2002年   42966篇
  2001年   74171篇
  2000年   75728篇
  1999年   62646篇
  1998年   17765篇
  1997年   16029篇
  1996年   16168篇
  1995年   15341篇
  1994年   13889篇
  1993年   13056篇
  1992年   46694篇
  1991年   44303篇
  1990年   42264篇
  1989年   40304篇
  1988年   36962篇
  1987年   36006篇
  1986年   33542篇
  1985年   31928篇
  1984年   24401篇
  1983年   20518篇
  1982年   12597篇
  1981年   11165篇
  1979年   21236篇
  1978年   15025篇
  1977年   12476篇
  1976年   11719篇
  1975年   11952篇
  1974年   14345篇
  1973年   13884篇
  1972年   12944篇
  1971年   11749篇
  1970年   11165篇
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
91.
92.
A new semi-empirical formula for the evaluation of (n,(3)He) reaction cross-sections at the energy of 14.6 and 20 MeV is presented. Formula was derived using the analytical expression for the evaluation of the (3)He spectrum within the frame of pre-equilibrium exciton model. The systematics obtained is compared with the empirical formula for the (n,(3)He) reaction cross-section.  相似文献   
93.
94.
95.
96.
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   
97.
98.
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   
99.
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   
100.
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   
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