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   2147499篇
  免费   148292篇
  国内免费   3980篇
耳鼻咽喉   31514篇
儿科学   68013篇
妇产科学   60446篇
基础医学   303179篇
口腔科学   62939篇
临床医学   187920篇
内科学   409780篇
皮肤病学   48775篇
神经病学   168383篇
特种医学   84344篇
外国民族医学   595篇
外科学   327421篇
综合类   48589篇
现状与发展   7篇
一般理论   677篇
预防医学   153203篇
眼科学   51402篇
药学   165689篇
  10篇
中国医学   5062篇
肿瘤学   121823篇
  2018年   20750篇
  2016年   18583篇
  2015年   20729篇
  2014年   28815篇
  2013年   43154篇
  2012年   57632篇
  2011年   61076篇
  2010年   36098篇
  2009年   34421篇
  2008年   57524篇
  2007年   62315篇
  2006年   63141篇
  2005年   60575篇
  2004年   58587篇
  2003年   56412篇
  2002年   55063篇
  2001年   104508篇
  2000年   107292篇
  1999年   90252篇
  1998年   24076篇
  1997年   21636篇
  1996年   21141篇
  1995年   19871篇
  1994年   18440篇
  1993年   17345篇
  1992年   69485篇
  1991年   67134篇
  1990年   65984篇
  1989年   64035篇
  1988年   59050篇
  1987年   57914篇
  1986年   55217篇
  1985年   52332篇
  1984年   38914篇
  1983年   33056篇
  1982年   19304篇
  1981年   17403篇
  1979年   36698篇
  1978年   25786篇
  1977年   22628篇
  1976年   20325篇
  1975年   23065篇
  1974年   27240篇
  1973年   26566篇
  1972年   25289篇
  1971年   23678篇
  1970年   22196篇
  1969年   21354篇
  1968年   19697篇
  1967年   17648篇
排序方式: 共有10000条查询结果,搜索用时 20 毫秒
81.
This study was performed to evaluate the surgical strategy in patients with calvarial tumours, in order to design and modify a robot-assisted trepanation system. A total of 75 patients underwent craniectomy for the treatment of calvarial tumours during the 10-year period from 1993 to 2002. The patients' complaints, the size, location and histology of the tumour, and the various cranioplasty techniques used were analysed retrospectively. In a second procedure several craniectomies at typical locations according to the study's results were performed in a laboratory setting using a hexapod robotic tool, constructed at the Helmholtz-Institute, RWTH Aachen University, and plastic model heads. The workflow was documented and the reproducibility and the accuracy of the procedure were registered. A total of 83 surgical procedures were performed on 75 patients. The majority (87 %) of lesions treated surgically were located in the frontal, temporal and anterior parts of the parietal region. Histological examination revealed benign lesions in 66 % of the patients and dural involvement in 46 %. According to these results craniectomies were performed using the robotic system. Mean positioning accuracy of the robotic system while milling was 0.24 mm, with a standard deviation of 0.04 mm, and maximum error under 1 mm. Craniectomies leaving a 1-mm layer of the tabula interna intact to ensure a healthy dura were performed in several regions successfully. The majority of calvarial tumours, requiring surgical treatment in our patients, were located in cosmetically relevant areas in which drilling can be carried out with the robotic trepanation system. Consequently, the surgical approach had to be planned carefully in order to achieve a good cosmetic outcome.  相似文献   
82.
BG Aktuell     
This paper gives an overview of the changes in the sector of accident insurance companies over recent months and a prognosis for the changes that can still be expected, especially with reference to the election results.  相似文献   
83.
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   
84.
85.
86.
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   
87.
OBJECTIVE: To determine whether under-reporting of rheumatic fever occurs at hospital, municipal, provincial and national levels of the South African health system. BACKGROUND: Information on the incidence of rheumatic fever (RF) and the prevalence of rheumatic heart disease (RHD) is required for the prevention of valvular heart disease in developing countries. In South Africa, RF was made a notifiable condition in 1989. It has recently been suggested that the reporting of RF cases may be incomplete, possibly because of underreporting by health care professionals and deficient administration of the disease notification system in South Africa. METHOD AND RESULTS: We assessed whether underreporting of RF cases occurs by comparing the numbers of RF cases reported per year at hospital, municipal, provincial and national levels from 1990 to 2004. There was a fall in the number of RF cases reported per year at national and provincial level over the 15 years of observation. A detailed analysis of the number of RF cases reported at hospital, municipal and provincial level for a 5-year period showed that more cases were diagnosed in one hospital (serving a smaller population) than were captured at municipal and provincial level (serving a larger population), suggesting underreporting by health care professionals. There were discrepancies in the number of cases reported at municipal, provincial and national level, suggesting poor administration of the notification system. CONCLUSION: There appears to be underreporting of RF cases by health care professionals, and poor administration of the RF notification system. Health care professionals need to be educated about the statutory requirement to notify all RF cases in South Africa. An effective national disease notification system is required.  相似文献   
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