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   21607篇
  免费   1715篇
  国内免费   52篇
耳鼻咽喉   115篇
儿科学   851篇
妇产科学   713篇
基础医学   2997篇
口腔科学   329篇
临床医学   2930篇
内科学   3850篇
皮肤病学   286篇
神经病学   2613篇
特种医学   318篇
外科学   1773篇
综合类   260篇
一般理论   46篇
预防医学   2935篇
眼科学   389篇
药学   1469篇
中国医学   28篇
肿瘤学   1472篇
  2023年   217篇
  2022年   245篇
  2021年   476篇
  2020年   351篇
  2019年   548篇
  2018年   597篇
  2017年   468篇
  2016年   472篇
  2015年   540篇
  2014年   788篇
  2013年   1120篇
  2012年   1612篇
  2011年   1663篇
  2010年   891篇
  2009年   853篇
  2008年   1358篇
  2007年   1503篇
  2006年   1484篇
  2005年   1390篇
  2004年   1360篇
  2003年   1242篇
  2002年   1155篇
  2001年   176篇
  2000年   137篇
  1999年   159篇
  1998年   234篇
  1997年   199篇
  1996年   146篇
  1995年   139篇
  1994年   106篇
  1993年   130篇
  1992年   86篇
  1991年   77篇
  1990年   66篇
  1989年   66篇
  1988年   54篇
  1987年   51篇
  1986年   43篇
  1985年   51篇
  1984年   53篇
  1983年   69篇
  1982年   75篇
  1981年   65篇
  1980年   70篇
  1979年   44篇
  1978年   41篇
  1977年   39篇
  1976年   45篇
  1974年   39篇
  1973年   44篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
12.
Self-etching primers have recently been introduced to simplify the orthodontic bonding process. The aim of this study was to compare the effectiveness of such a product with conventional 2-stage etching and priming with 37% o-phosphoric acid and a conventional unfilled primer. Twenty consecutive patients having orthodontic bonds placed were selected to participate in this cross-mouth control study. Diagonally opposite quadrants were randomly allocated to either the self-etching primer group or the conventional etching and priming group. A total of 364 teeth were bonded with a light-cured diacrylate adhesive; bond failures were then monitored over 6 months. There were 20 bond failures (10.99%) in the self-etching primer group and 9 bond failures (4.95%) in the conventional etch and priming group over this period. The results were analyzed with the McNemar test and 95% confidence interval. The difference between the failure proportions was -0.06 with an associated 95% confidence interval of -0.121 to 0.001. This study produced weak evidence to suggest that bond failures with a self-etching primer will be higher than those with conventional etching and priming. This increased likelihood of bond failure must be weighed against the time advantage of the self-etching primer when used at the initial bonding appointment.  相似文献   
13.
Mapping brain size and cortical gray matter changes in elderly depression.   总被引:1,自引:0,他引:1  
BACKGROUND: In elderly depression, volumetric brain imaging findings suggest abnormalities of the frontal lobe, particularly the orbitofrontal cortex, and the hippocampus. No studies to date have mapped cortical abnormalities over the entire brain surface in major depression. Here, we conducted detailed spatial analyses of brain size and gray matter within the cortical mantle in elderly patients with major depression. METHODS: High-resolution, three-dimensional, structural magnetic resonance imaging data and cortical pattern matching methods were used in 24 depressed elderly patients and 19 group-matched controls to measure local brain size and proportions of gray matter at thousands of homologous cortical surface locations. RESULTS: Prominent brain size reductions were observed in the depressed subjects in the orbitofrontal cortex bilaterally. Cortical gray matter measurements revealed significant gray matter increases in the orbitofrontal cortex, adjacent to focal trend level significant decreases of gray matter in the same region. Depressed patients also exhibited significant gray matter increases in parietal cortices, as well as the left temporal cortex. CONCLUSIONS: Complex cortical changes may contribute to the brain size reduction of the orbitofrontal cortex and to the gray matter abnormalities detected in orbitofrontal cortex and temporoparietal cortices, thereby providing a potentially new window into the pathophysiology of elderly depression.  相似文献   
14.
15.
This paper analyses the diverse services currently available for children under five in the UK, and considers the nature of the demand for them. It recounts the initiative made by Strathclyde Region to co-ordinate and integrate pre-five provision, administratively and at a service level. It then considers the efforts of other local authorities to integrate administratively and looks at some of the complexities of attempting to do so at a service level.  相似文献   
16.
Patients suffering from semantic dementia provide important constraints on theories of the structure and organisation of semantic memory. In this article we report one such patient, AM, whose progressive deterioration of semantics enables us to address the much-debated issue of whether conceptual structure is hierarchically organised. The hierarchical account predicts that brain damage should impair lower levels of the hierarchy (property information) before affecting higher level (category) information (Warrington and Shallice, Q. J. Exp. Psychol. 1975, 27, 635–657). We evaluate this prediction by repeated testing of AM in two studies—a semantic priming task and a verification task—over an 18 month period, contrasting the progressive deterioration of properties (functional and perceptual) and category relations (category co-ordinates and category labels). Properties were preserved longer than category information, arguing against a hierarchical account of semantic memory. In addition, functional properties were most robust to brain damage, supporting our claim that functional information plays a special role in semantic representations (Durrant-Peatfield et al., Proc. 19th Ann. Conf. of the Cognitive Science Society. Erlbaum, Mahwah, NJ, 1997, pp. 193–198. Tyler et al., Cognitive Neuropsychol. 1997, 14, 511–545).  相似文献   
17.
We present these 3 cases to alert others to the possibility of severe pain with rapid shrinkage of fibroids occurring during LHRH analogue treatment. We suggest management of such events should not be surgical except for vaginal excision of prolapsed fibroid polyps.  相似文献   
18.
Dermatofibrosarcoma protuberans (DFSP) previously called Morbus Darier is an intermediate grade sarcoma with a fairly high rate of recurrence, it occurs most commonly on the trunk and extremities but may also occur in the head and neck region. Treatment of choice is wide excision. A 69-year-old female patient with a 57-year history of dermatofibrosarcoma protuberans is presented. The lesion appeared on the right forehead and both eyelids at the age of 12 years. The patient required 64 surgeries mostly for the head and neck lesions.  相似文献   
19.
20.
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