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   2011308篇
  免费   164622篇
  国内免费   7698篇
耳鼻咽喉   27320篇
儿科学   62569篇
妇产科学   56484篇
基础医学   280661篇
口腔科学   57058篇
临床医学   180004篇
内科学   402088篇
皮肤病学   45480篇
神经病学   164931篇
特种医学   82048篇
外国民族医学   431篇
外科学   314835篇
综合类   51392篇
现状与发展   4篇
一般理论   653篇
预防医学   160815篇
眼科学   45194篇
药学   144104篇
  5篇
中国医学   3546篇
肿瘤学   104006篇
  2018年   19269篇
  2016年   17964篇
  2015年   20439篇
  2014年   28757篇
  2013年   43337篇
  2012年   54703篇
  2011年   58348篇
  2010年   35750篇
  2009年   34527篇
  2008年   54796篇
  2007年   58921篇
  2006年   59812篇
  2005年   58120篇
  2004年   56042篇
  2003年   54346篇
  2002年   51769篇
  2001年   90951篇
  2000年   93362篇
  1999年   78376篇
  1998年   23985篇
  1997年   21597篇
  1996年   22310篇
  1995年   22005篇
  1994年   20704篇
  1993年   19496篇
  1992年   65789篇
  1991年   64271篇
  1990年   62183篇
  1989年   59411篇
  1988年   55441篇
  1987年   54612篇
  1986年   51574篇
  1985年   49982篇
  1984年   38415篇
  1983年   32545篇
  1982年   20575篇
  1981年   18725篇
  1980年   17631篇
  1979年   36368篇
  1978年   26350篇
  1977年   22238篇
  1976年   20415篇
  1975年   21731篇
  1974年   26158篇
  1973年   25045篇
  1972年   23523篇
  1971年   21654篇
  1970年   20225篇
  1969年   19288篇
  1968年   17706篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
The aim of the present study was to explore differences in the clinical expression, clinical diagnoses and management of airway diseases in a primary-care setting. Patients aged >or=35 yrs who had ever smoked were enrolled when they presented for any reason to one of eight rural primary-care practices. Respiratory symptom questionnaires and spirometry were administered. In total, 1,034 patients had acceptable and reproducible spirometry, of whom 550 (53%) were males and 484 (47%) were females. Males smoked more than females (41.2 versus 29.2 pack-yrs) respectively, and were more likely to have a pre-bronchodilator forced expiratory volume in one second/forced vital capacity <0.70 at 22.4 versus 11.8%, respectively. However, more females than males reported breathlessness (51.0 versus 42.8%, respectively), a prior diagnosis compatible with airflow obstruction and taking respiratory medications (23.4 versus 14.9%, respectively). In conclusion, the current results suggest that females are more likely than males to report breathlessness and be prescribed respiratory medications independent of differences in the severity of airflow obstruction.  相似文献   
63.
64.
65.
66.
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   
67.
For many parents stopping life-sustaining medical treatment on their dying infant is psychologically impossible. Dostoevsky's insights into human behavior, particularly the fact that individuals do not want the anxiety and guilt associated with responsibility for making difficult decisions, might change the way physicians approach parents for permission to withdraw life-prolonging medical interventions on dying infants.  相似文献   
68.
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   
69.
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   
70.
Summary: The mosaic (Atp7a mo-ms ) is an X-linked, lethal mutation in mice. In mosaic mutant males, many clinical features characteristic of defective copper metabolism have been observed and they die at the age of 15 days, exhibiting strongsimilarities to the brindled and macular mutants. About 4% of the mutant males live to sexual maturity and some of them are fertile. In this paper, alterationsin the structure of the kidney from adult mutants are described. Owing to an inherited defect of efflux, copper is accumulated in the kidney of the mutants up to a toxic level and this leads to severe damage of the renal cortex. Pathological changes in the kidney mostly affected the structure of the renal corpuscle and renaltubules.  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