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   180570篇
  免费   33083篇
  国内免费   2478篇
耳鼻咽喉   5393篇
儿科学   6307篇
妇产科学   2992篇
基础医学   7229篇
口腔科学   2511篇
临床医学   29625篇
内科学   52849篇
皮肤病学   7830篇
神经病学   17927篇
特种医学   7420篇
外国民族医学   6篇
外科学   44948篇
综合类   598篇
现状与发展   72篇
一般理论   51篇
预防医学   9276篇
眼科学   4422篇
药学   3198篇
中国医学   72篇
肿瘤学   13405篇
  2024年   697篇
  2023年   4853篇
  2022年   1398篇
  2021年   3498篇
  2020年   6263篇
  2019年   2569篇
  2018年   7876篇
  2017年   7708篇
  2016年   8814篇
  2015年   8857篇
  2014年   16127篇
  2013年   16717篇
  2012年   7296篇
  2011年   7501篇
  2010年   11390篇
  2009年   15169篇
  2008年   7694篇
  2007年   6206篇
  2006年   8548篇
  2005年   5887篇
  2004年   5062篇
  2003年   4030篇
  2002年   4017篇
  2001年   4017篇
  2000年   3174篇
  1999年   3457篇
  1998年   4042篇
  1997年   3815篇
  1996年   3641篇
  1995年   3487篇
  1994年   2225篇
  1993年   1846篇
  1992年   1585篇
  1991年   1589篇
  1990年   1215篇
  1989年   1315篇
  1988年   1157篇
  1987年   977篇
  1986年   1047篇
  1985年   884篇
  1984年   823篇
  1983年   776篇
  1982年   842篇
  1981年   701篇
  1980年   672篇
  1979年   455篇
  1978年   513篇
  1977年   586篇
  1975年   405篇
  1972年   366篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
This paper reports the proceedings of the discussion panel assigned to look at clinical aspects of quality in emergency medicine. One of the seven stated objectives of the Academic Emergency Medicine consensus conference on quality in emergency medicine was to educate emergency physicians regarding quality measures and quality improvement as essential aspects of the practice of emergency medicine. Another topic of interest was a discussion of the value of information technology in facilitating quality care in the clinical practice of emergency medicine. It is important to note that this is not intended to be a comprehensive review of this extensive topic, but instead is designed to report the discussion that occurred at this session of the consensus conference.  相似文献   
42.
43.
This study evaluates the potential for endothelial seeding of a collagen-impregnated Dacron graft with or without surface modifiers (fibronectin, heparin) to attach and retain these cells during flow. Human umbilical endothelial cells were harvested, cultured, labeled with Indium111-oxine and seeded onto 30 mm X 4 mm diameter grafts. Six graft surfaces were studied: 1) a collagen-impregnated Dacron graft, HemashieldR (C); 2) C + fibronectin (C + F); 3) C + heparin (C + H); 4) C + F + H; 5) HytrelR + F (Hyt + F); and 6) Hyt + F + H. Radioactive loss determined the percentage attachment and then percentage retention of labeled inoculum after a one-hour in vitro perfusion. Scanning electron and light microscopy demonstrated the endothelium on the graft surface following perfusion. Fibronectin-coated grafts had a significantly higher percentage attachment than those without fibronectin (ANOVA, P less than 0.05). However, the percentage retention following perfusion was similar for all Dacron grafts and statistically inferior to the HytrelR grafts studied (ANOVA, P less than 0.05). SEM evaluation of the C + F + H graft surface was qualitatively the most impressive Dacron surface for seeding, yet was inferior to the HytrelR graft. We conclude that fibronectin benefits the initial attachment of endothelium to collagen-coated Dacron rivaling the HytrelR surface. Fibronectin does not improve percentage retention of the HemashieldR surface during perfusion, therefore, some of its initial benefit is lost.  相似文献   
44.
Objective: The study goal was to compare the laser spot size created using reflective and refractive micromanipulators with a CO2 laser and to determine the sensitivity of spot size to laser power. Study Design and Setting: A CO2 laser and operating microscope (400-mm focal length) was coupled to either a reflective (Cassegrain-like) or refractive micromanipulator. Laser spot size was determined by measuring the region of ablation created by laser irradiation of wood (dry tongue depressors), exposed photographic film, and agar gel using optical micrometry. Laser power varied from 0.5 to 20 W with pulse durations of 0.1 and 0.5 second. Results: The reflective micromanipulator demonstrated overall smaller spot sizes for a given laser power and lower incremental change in spot size with increasing power. The reflective design demonstrated less sensitivity to increases in laser power. Conclusions: Micromanipulator optical design can result in significant differences in laser spot size. The reflective device used in this study demonstrated less sensitivity to increasing laser power. (Otolaryngol Head Neck Surg 2002;126:593-597.)  相似文献   
45.
Although lesions of the pterygopalatine space are uncommon, there are instances in which this relatively inaccessible region must be entered for biopsy or excision of masses. Traditional open approaches to the pterygopalatine space, involving external or intraoral incisions, provide limited visualization and carry associated morbidities. The evolution and advancement of endoscopic sinus surgical technique in recent years has led to its application to anatomic areas outside the strict limits of the sinonasal cavities. Such minimally invasive approaches are safe, effective, and spare unnecessary discomfort to the patient. This article describes the authors' method for performing an endoscopic approach to the pterygopalatine space.  相似文献   
46.
47.
The literature suggests that pain in the elderly, especially among seniors with dementia, is under-assessed and under-treated.This qualitative study solicited the perspectives of seniors, front-line nursing staff, nursing-home administrators, and informal caregivers of seniors with dementia on the current status of pain assessment and management. The views of these participants complement the research findings reported in the literature. While some of their explanations and potential solutions concerning under-treatment of pain in seniors echo views that have been presented in the literature, the participants also pointed to factors and avenues that have been given less formal consideration (e.g., systemic barriers to effective assessment and treatment of pain).They also highlighted the need for pain-control strategies beyond medication. The implications of these findings are discussed.  相似文献   
48.
49.
50.
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