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   20654篇
  免费   1427篇
  国内免费   57篇
耳鼻咽喉   134篇
儿科学   452篇
妇产科学   277篇
基础医学   2786篇
口腔科学   327篇
临床医学   2589篇
内科学   3597篇
皮肤病学   198篇
神经病学   1843篇
特种医学   709篇
外科学   2880篇
综合类   232篇
一般理论   28篇
预防医学   2660篇
眼科学   440篇
药学   1613篇
中国医学   35篇
肿瘤学   1338篇
  2024年   15篇
  2023年   126篇
  2022年   187篇
  2021年   488篇
  2020年   313篇
  2019年   443篇
  2018年   520篇
  2017年   399篇
  2016年   437篇
  2015年   583篇
  2014年   754篇
  2013年   974篇
  2012年   1654篇
  2011年   1679篇
  2010年   955篇
  2009年   893篇
  2008年   1471篇
  2007年   1611篇
  2006年   1460篇
  2005年   1455篇
  2004年   1420篇
  2003年   1339篇
  2002年   1159篇
  2001年   152篇
  2000年   114篇
  1999年   176篇
  1998年   223篇
  1997年   150篇
  1996年   134篇
  1995年   104篇
  1994年   112篇
  1993年   88篇
  1992年   56篇
  1991年   51篇
  1990年   36篇
  1989年   40篇
  1988年   28篇
  1987年   36篇
  1986年   30篇
  1985年   28篇
  1984年   30篇
  1983年   39篇
  1982年   25篇
  1981年   29篇
  1980年   21篇
  1979年   12篇
  1978年   14篇
  1977年   7篇
  1976年   16篇
  1961年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
In an attempt to tap underlying competencies, the ability of children with autism to comprehend pretend acts carried out by an experimenter was compared with that shown by controls. These acts consisted of the pouring of a pretend substance from an appropriate container onto a target figure. There was no significant difference in the groups' ability to identify the pretend substance involved, to predict the pretend outcome of the actions, or to reflect on the pretend nature of the episodes. However, the performance of controls on these latter two tasks was surprisingly poor, limiting the implications that might be drawn from the observed absence of group differences in comprehension abilities.We are very grateful to the teachers and headteachers of the following schools for their cooperation and assistance throughout the period of this research: John Worrall School, Sheffield; Doucecroft School, Kelvedon; East Hill First and Middle School, Sheffield; East Hill Second School, Sheffield; Mossbrook School, Sheffield; Priory School, Doncaster; The Rowan School, Dore; St. Mary's School, Sheffield. We also thank James Russell for his helpful comments of earlier drafts of this paper.  相似文献   
62.
63.

Background  

Persisting neck pain is common in society. It has been reported that the prevalence of neck pain in office workers is much higher than in the general population. The costs to the worker, employer and society associated with work-related neck pain are known to be considerable and are escalating. The factors that place office workers at greater risk of developing neck pain are not understood. The aim of this study is to investigate the incidence and risk factors of work-related neck pain in Australian office workers.  相似文献   
64.
Metastasis (the spread of cancer from a primary tumor to secondary organs) is responsible for most cancer deaths. The ability to follow the fate of a population of tumor cells over time in an experimental animal would provide a powerful new way to monitor the metastatic process. Here we describe a magnetic resonance imaging (MRI) technique that permits the tracking of breast cancer cells in a mouse model of brain metastasis at the single-cell level. Cancer cells that were injected into the left ventricle of the mouse heart and then delivered to the brain were detectable on MR images. This allowed the visualization of the initial delivery and distribution of cells, as well as the growth of tumors from a subset of these cells within the whole intact brain volume. The ability to follow the metastatic process from the single-cell stage through metastatic growth, and to quantify and monitor the presence of solitary undivided cells will facilitate progress in understanding the mechanisms of brain metastasis and tumor dormancy, and the development of therapeutics to treat this disease.  相似文献   
65.
66.
67.
A device called the Dex Frame has recently been marketed as an aid for children with specific learning difficulties. Using a test of reading speed and a test of reading accuracy we have attempted to evaluate the device. Two groups of children with learning difficulties were used, one having sole use of the device and being allowed to carry it with them and a second group who only used the device when attending for remedial tuition and assessment. The results show that no significant improvement occurred in reading performance of the groups with learning difficulties using the Dex Frame as compared with a control group. The teachers of the groups did, however, feel that on an individual basis some children (< 10%) expressed that they felt more comfortable using the device.  相似文献   
68.
69.
BACKGROUND & AIMS: Refractory celiac disease (RCD) may be subdivided into RCD types I and II with phenotypically normal and aberrant intraepithelial T-cell populations, respectively. In RCD II, transition into enteropathy-associated T-cell lymphoma (EATL) is seen frequently. We have evaluated the effect of cladribine (2-CDA), a purine analogue inducing T-cell depletion, on clinical, histopathologic, and immunologic parameters, as well as the toxicity and side effects in a group of RCD II patients. METHODS: Between 2000 and 2005, 17 patients were included (8 men, 9 women). All patients had a clonal rearrangement of the T-cell receptor gamma gene and immunophenotyping showed an aberrant T-cell population lacking surface expression of CD3, CD8, and T-cell receptor alphabeta, in the presence of expression of surface CD103 and intracytoplasmic CD3. Treatment consisted of 2-CDA (0.1 mg/kg/day) intravenously for 5 days, given in 1-3 courses every 6 months depending on the response. RESULTS: All patients tolerated 2-CDA without serious side effects. Six patients (35.8%) showed a clinical improvement (weight gain, improvement of diarrhea, and hypoalbuminemia). In 10 patients (58.8%) a significant histologic improvement and in 6 patients (35.2%) a significant decrease in aberrant T cells was seen. Seven patients (41.1%) developed EATL and died subsequently. One patient died of progressive refractory state with emaciation. CONCLUSIONS: Treatment with 2-CDA in RCD II is feasible, well tolerated, and can induce clinical and histologic improvement as well as a significant decrease of aberrant T cells in a subgroup of patients, albeit it does not prevent EATL development. However, the earlier reported potential risk of precipitating an overt lymphoma should be taken into consideration.  相似文献   
70.
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