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   1389663篇
  免费   98045篇
  国内免费   3473篇
耳鼻咽喉   20510篇
儿科学   41574篇
妇产科学   39434篇
基础医学   193663篇
口腔科学   40783篇
临床医学   118534篇
内科学   272776篇
皮肤病学   31017篇
神经病学   110837篇
特种医学   55702篇
外国民族医学   439篇
外科学   216576篇
综合类   32827篇
现状与发展   7篇
一般理论   470篇
预防医学   96431篇
眼科学   32709篇
药学   104249篇
  11篇
中国医学   3390篇
肿瘤学   79242篇
  2018年   13482篇
  2016年   11821篇
  2015年   13440篇
  2014年   18834篇
  2013年   27974篇
  2012年   37090篇
  2011年   39284篇
  2010年   23196篇
  2009年   22209篇
  2008年   36988篇
  2007年   40365篇
  2006年   40687篇
  2005年   39403篇
  2004年   38062篇
  2003年   36989篇
  2002年   36207篇
  2001年   64326篇
  2000年   65958篇
  1999年   56029篇
  1998年   15186篇
  1997年   13844篇
  1996年   13295篇
  1995年   12567篇
  1994年   11731篇
  1992年   43029篇
  1991年   41498篇
  1990年   40775篇
  1989年   39781篇
  1988年   37155篇
  1987年   36580篇
  1986年   35051篇
  1985年   33262篇
  1984年   24983篇
  1983年   21182篇
  1982年   12821篇
  1981年   11692篇
  1979年   24001篇
  1978年   17158篇
  1977年   14904篇
  1976年   13440篇
  1975年   15319篇
  1974年   18125篇
  1973年   17605篇
  1972年   16836篇
  1971年   15733篇
  1970年   14936篇
  1969年   14365篇
  1968年   13478篇
  1967年   12032篇
  1966年   11277篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
82.
Abstract Chorea is a rare complication of polycythaemia vera. Polycythaemic chorea occurs predominantly in females and usually in generalised form. We present a 66-year-old woman with acute onset hemichorea-ballism with no vascular pathology in the basal ganglia region. A clear relationship was observed between the onset of chorea and worsening of haematological parameters in the patient. After repeated phlebotomies the patient's clinical status was improved. Polycythaemic chorea must be considered, especially in the elderly, as early diagnosis leads to effective treatment and prevention of complications.  相似文献   
83.
84.
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   
85.
86.
Intraoperative and postoperative free flap monitoring by means of oxygen tension measurement was carried out in 11 patients. We used an invasive flexible microcatheter that allowed for measurement of oxygen tension in all types of free flaps. Two cases of the measured flaps were buried free flaps which do not allow monitoring by clinical assessment. All flaps monitored in this study survived. One case of displacement of the microcatheter occurred. In one patient, the tissue pO2 monitor successfully detected early vascular thrombosis with subsequent reoperation and salvage of the free flap.  相似文献   
87.
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   
88.
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   
89.
PURPOSE: The advantages of a focometer (FOCOMETER) over other methods of refraction for use in developing countries are that it is lightweight, compact, relatively inexpensive, fairly quick, and easy to use with minimal training. This clinical trial compared the repeatability, validity, and ease of use of the focometer with an autorefractor. METHODS: The refractive status of the right eye of 80 participants was determined with an autorefractor (Canon RK3). Three measurements were also taken with the focometer. RESULTS: The spherical equivalent (M) of the focometer was 0.25 D more positive than the autorefractor (p < 0.001) and 84% of measurements were within 0.75 D of the autorefractor. The autorefractor detected astigmatism in 91% (73) of the eyes, whereas the focometer identified only 32% (26). The design of the clock target restricts cylinder axis accuracy to the nearest 15 degrees . There was evidence of a learning effect for the focometer: the second and third measurements were more repeatable in the untrained group. There were no differences between the mean (1.03 +/- 2.28) and third focometer (-1.05 +/- 2.32) measurements (p = 0.34). However, using the third focometer measurement, 94% of participants had visual acuities of at least 6/12(-2). CONCLUSIONS: This study highlighted the focometer's restricted power range, inaccuracy of astigmatism and axis determination, and dependence on subject understanding and compliance. Therefore, in most clinical settings, the focometer would not be adequate for quantifying refractive error, but the focometer spherical equivalent was within acceptable limits of the autorefractor, and the visual acuity with lenses determined by the focometer indicates its potential usefulness in public health settings, especially where only spherical ready-made spectacles are dispensed. There may be more cost-effective ways to determine refractive error in these circumstances. A potentially important enhancement in focometer methodology that improves its ease of use was identified: use only the third measurement for each eye.  相似文献   
90.
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