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   21568篇
  免费   1472篇
  国内免费   57篇
耳鼻咽喉   129篇
儿科学   470篇
妇产科学   307篇
基础医学   2807篇
口腔科学   334篇
临床医学   2706篇
内科学   3680篇
皮肤病学   205篇
神经病学   1951篇
特种医学   768篇
外科学   3157篇
综合类   295篇
一般理论   29篇
预防医学   2733篇
眼科学   432篇
药学   1694篇
中国医学   35篇
肿瘤学   1365篇
  2024年   15篇
  2023年   130篇
  2022年   133篇
  2021年   515篇
  2020年   325篇
  2019年   473篇
  2018年   548篇
  2017年   426篇
  2016年   454篇
  2015年   616篇
  2014年   797篇
  2013年   1032篇
  2012年   1728篇
  2011年   1731篇
  2010年   987篇
  2009年   924篇
  2008年   1523篇
  2007年   1668篇
  2006年   1502篇
  2005年   1495篇
  2004年   1451篇
  2003年   1369篇
  2002年   1189篇
  2001年   182篇
  2000年   135篇
  1999年   186篇
  1998年   239篇
  1997年   160篇
  1996年   139篇
  1995年   113篇
  1994年   115篇
  1993年   96篇
  1992年   64篇
  1991年   56篇
  1990年   48篇
  1989年   53篇
  1988年   44篇
  1987年   46篇
  1986年   38篇
  1985年   38篇
  1984年   34篇
  1983年   38篇
  1982年   31篇
  1981年   29篇
  1980年   28篇
  1979年   11篇
  1978年   14篇
  1977年   16篇
  1976年   18篇
  1970年   12篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
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   
72.
73.

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   
74.
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   
75.
76.
77.
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   
78.
79.
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   
80.
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