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   34587篇
  免费   2167篇
  国内免费   204篇
耳鼻咽喉   319篇
儿科学   574篇
妇产科学   464篇
基础医学   4918篇
口腔科学   902篇
临床医学   3555篇
内科学   7261篇
皮肤病学   665篇
神经病学   4007篇
特种医学   1980篇
外科学   5508篇
综合类   194篇
一般理论   7篇
预防医学   1452篇
眼科学   702篇
药学   1995篇
中国医学   68篇
肿瘤学   2387篇
  2024年   28篇
  2023年   273篇
  2022年   523篇
  2021年   903篇
  2020年   633篇
  2019年   821篇
  2018年   936篇
  2017年   804篇
  2016年   940篇
  2015年   1153篇
  2014年   1380篇
  2013年   1698篇
  2012年   2722篇
  2011年   2853篇
  2010年   1705篇
  2009年   1545篇
  2008年   2435篇
  2007年   2447篇
  2006年   2289篇
  2005年   2239篇
  2004年   2023篇
  2003年   1835篇
  2002年   1701篇
  2001年   339篇
  2000年   257篇
  1999年   323篇
  1998年   332篇
  1997年   249篇
  1996年   196篇
  1995年   166篇
  1994年   144篇
  1993年   136篇
  1992年   96篇
  1991年   87篇
  1990年   83篇
  1989年   55篇
  1988年   52篇
  1987年   50篇
  1986年   42篇
  1985年   42篇
  1984年   46篇
  1983年   33篇
  1982年   40篇
  1981年   32篇
  1980年   18篇
  1979年   12篇
  1978年   17篇
  1977年   14篇
  1975年   12篇
  1974年   16篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
BACKGROUND: Common clinical forms of oral lichen planus (OLP) and oral lichenoid reactions (OLR) are erythematous (ERY) or reticular (RET). The purpose of this study was to find histopathological changes that differ between these forms. METHODS: Epithelial thickness, epithelial proliferation rate, apoptosis, and HLA-DR expression were compared among 10 reticular and 12 erythematous lesions, and 11 normal oral mucosa samples (NOM). RESULTS: The epithelium in ERY was thinner than in NOM, whereas RET showed values between ERY and NOM. Cell proliferation increased significantly in ERY as compared with RET and NOM, with no difference between RET and NOM. Relative numbers of epithelial cell nuclei displaying visible chromatin condensation were reduced in ERY form. CONCLUSIONS: The markedly increased cell proliferation in ERY supports the notion that this form displays a higher disease activity as compared to RET. It can therefore be important to study each disease form separately.  相似文献   
3.
The adult mammalian central nervous system (CNS) lacks the capacity to support axonal regeneration. There is increasing evidence to suggest that astrocytes, the major glial population in the CNS, may possess both axon-growth promoting and axon-growth inhibitory properties and the latter may contribute to the poor regenerative capacity of the CNS. In order to examine the molecular differences between axon-growth permissive and axon-growth inhibitory astrocytes, a panel of astrocyte cell lines exhibiting a range of axon-growth promoting properties was generated and analysed. No clear correlation was found between the axon-growth promoting properties of these astrocyte cell lines with: (i) the expression of known neurite-outgrowth promoting molecules such as laminin, fibronectin andN-cadherin; (ii) the expression of known inhibitory molecules such tenascin and chondroitin sulphate proteoglycan; (iii) plasminogen activator and plasminogen activator inhibitor activity; and (iv) growth cone collapsing activity. EM studies on aggregates formed from astrocyte cell lines, however, revealed the presence of an abundance of extracellular matrix material associated with the more inhibitory astrocyte cell lines. When matrix deposited by astrocyte cell lines was assessed for axon-growth promoting activity, matrix from permissive lines was found to be a good substrate, whereas matrix from the inhibitory astrocyte lines was a poor substrate for neuritic growth. Our findings, taken together, suggest that the functional differences between the permissive and the inhibitory astrocyte cell lines reside largely with the ECM.  相似文献   
4.
5.
6.
7.
Abstract Background: Primary shoulder hemiarthroplasty is an established treatment modality for complex fractures of the proximal humerus. Long-term functional outcome is often disappointing. However, little is known about social implications particularly in the elderly. Methods: A single-institution case series of consecutive geriatric patients (age > 70 years) treated with shoulder hemiarthroplasty for complex fractures of the proximal humerus between 1994 and 1997 was analysed. Postoperative morbidity, long-term function, radiological outcome and social implications were evaluated. Results: Seventy-seven patients fulfilled the study criteria. Median age at the time of operation was 80 years (range 70–93 years). Systemic and local postoperative complications were observed in 8% including 2 patients (3%) with revision surgery. Postoperative mortality was 1%. Forty-eight patients (62%) were available for follow-up (median 49 months, range 25–80 months), 22 (29%) died from causes unrelated to hemiarthroplasty before follow-up and 7 patients (9%) did not attend follow-up examination. Median Constant-Murley score was 41 points (range 17–77 points). Long-term results concerning pain were satisfying. The Oxford shoulder score ranged from 14 to 40 (median 30). Forty-one patients (85%) still lived in their original environment and managed their daily life independently despite poor shoulder function. Four patients (8%) lived in a retirement home and 3 (6%) in a nursery home. Eighty percent of our patients were still able to use public transportation, do the daily shopping and wash their whole body by themselves. Conclusion: Most patients managed their daily life independently despite poor shoulder function.  相似文献   
8.
9.
We report a case of recurrent inguinal lymphocele formation after inguinal lymphadenectomy treated by lymphographic mapping and selective ligation of the lymphatic vessels. Lymphographic mapping was performed by puncturing a lymphatic vessel at the dorsum of the foot. After isolating the vessels that drained into the lymphocele, they were clipped and divided through a small skin incision. The described technique showed an instant and complete suspension of the lymph secretion with subsequent complete healing. Lymphatic mapping and selective ligation of afferent lymphatic vessels proved to be an effective treatment of a recurrent inguinal lymphocele.  相似文献   
10.
The synthesis and properties of segmented ABA triblock and (AB)n multiblock copolymer systems with 6,6′-disubstituted 2,2′-bipyridine (bpy) building blocks B and poly(oxytetramethylene) soft segments A are described. The access to the disubstituted bipyridines in large scale quantities was achieved by modification of conventional synthetic routes. In the presence of copper(I) ions these polymers formed mononuclear [Cu(I)(bpy)2] complexes in solution through self-assembly. The complexed copolymers were microphase separated systems in bulk with nano to mesoscopic superstructures consisting of copper-bpy complex aggregates in a polyether matrix. The thermal, mechanical and elastomer properties of the block copolymers varied with composition.  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