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   1487182篇
  免费   110993篇
  国内免费   2862篇
耳鼻咽喉   20683篇
儿科学   49746篇
妇产科学   38818篇
基础医学   208178篇
口腔科学   37627篇
临床医学   132742篇
内科学   301246篇
皮肤病学   30838篇
神经病学   121710篇
特种医学   60316篇
外国民族医学   673篇
外科学   228946篇
综合类   29311篇
现状与发展   2篇
一般理论   543篇
预防医学   110579篇
眼科学   32944篇
药学   108594篇
  3篇
中国医学   2716篇
肿瘤学   84822篇
  2021年   12601篇
  2019年   13437篇
  2018年   18425篇
  2017年   13846篇
  2016年   15162篇
  2015年   17390篇
  2014年   24461篇
  2013年   36212篇
  2012年   51130篇
  2011年   53926篇
  2010年   31736篇
  2009年   30147篇
  2008年   50705篇
  2007年   54047篇
  2006年   53958篇
  2005年   52689篇
  2004年   51070篇
  2003年   48721篇
  2002年   47523篇
  2001年   65730篇
  2000年   67796篇
  1999年   58190篇
  1998年   17599篇
  1997年   15735篇
  1996年   15924篇
  1995年   15032篇
  1994年   14138篇
  1993年   13149篇
  1992年   45434篇
  1991年   44296篇
  1990年   42919篇
  1989年   40778篇
  1988年   37500篇
  1987年   36762篇
  1986年   34195篇
  1985年   32890篇
  1984年   24969篇
  1983年   20990篇
  1982年   12659篇
  1981年   11565篇
  1979年   21777篇
  1978年   15292篇
  1977年   12943篇
  1976年   12079篇
  1975年   12906篇
  1974年   14944篇
  1973年   14362篇
  1972年   13105篇
  1971年   11872篇
  1970年   11153篇
排序方式: 共有10000条查询结果,搜索用时 22 毫秒
51.
Clinicopathological and electron microscopical findings of eight cases of enzootic nasal adenocarcinoma of sheep, diagnosed solely in one big flock in Slovenia between years 2001 and 2003 are described. All affected sheep were female, their mean age was 4.5 ± 1.5 years and they either belonged to the Istrian pramenka breed (five sheep) or were crossbreeds (three sheep). Tumours that arose from the ethmoid area of the nasal cavity were unilateral in six cases (75%) and bilateral in two cases (25%). All tumours were classified as adenocarcinomas by histopathological examination and they displayed either a combination of tubular and papillary growth or less often solely tubular proliferation. No metastases were detected in regional lymph nodes, brain or other organs. Electron microscopical studies performed on the reprocessed paraffin‐embedded tissues revealed the presence of the virus‐like particles with an average diameter between 70 and 90 nm.  相似文献   
52.
Systems of care (SOCs) have been developed throughout the country to meet the needs of children with severe emotional disturbances (SED) and their families. In these SOCs, multiple agencies and disciplines are expected to work together with informal community supports to address families' needs (Stroul & Friedman, 1986a). A review of the literature on the impact of SOCs suggests: (a) communities' service delivery systems change; and (b) children experience modest improvements in symptomatology and functioning. At the same time, little is known about (a) which components of the SOC approach, at what levels, are necessary to impact child and family outcomes; (b) the degree to which SOCs affect other family members, beyond the target child; and (c) the impact of community contexts and supports in SOCs. Future research should improve measurement of key SOC constructs, examine the relation between specific levels of implementation and outcomes for the entire family, and investigate the impact of broader community systems and supports on families within SOCs. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 655–674, 2004.  相似文献   
53.
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   
54.
55.
Dear Sir In the recently published Task force report, under section ‘Fibrinolyticregimens’, the authors recommend not to re-administerstreptokinase for at least 10 years. The reference supportingthis statement is Ref. 51. After evaluating this paper and lookinginto the literature my comments  相似文献   
56.
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   
57.
58.
59.
60.
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