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   156663篇
  免费   31524篇
  国内免费   2417篇
耳鼻咽喉   5187篇
儿科学   5471篇
妇产科学   2474篇
基础医学   3761篇
口腔科学   1593篇
临床医学   27023篇
内科学   48955篇
皮肤病学   7554篇
神经病学   15146篇
特种医学   6516篇
外科学   42384篇
综合类   242篇
现状与发展   72篇
预防医学   7079篇
眼科学   3396篇
药学   1370篇
中国医学   25篇
肿瘤学   12356篇
  2024年   687篇
  2023年   4830篇
  2022年   1233篇
  2021年   3163篇
  2020年   6087篇
  2019年   2214篇
  2018年   7490篇
  2017年   7411篇
  2016年   8511篇
  2015年   8511篇
  2014年   15608篇
  2013年   15752篇
  2012年   5654篇
  2011年   5747篇
  2010年   10479篇
  2009年   14339篇
  2008年   6017篇
  2007年   4284篇
  2006年   6695篇
  2005年   4037篇
  2004年   3313篇
  2003年   2248篇
  2002年   2312篇
  2001年   4041篇
  2000年   3285篇
  1999年   3417篇
  1998年   3718篇
  1997年   3528篇
  1996年   3413篇
  1995年   3251篇
  1994年   1996篇
  1993年   1613篇
  1992年   1530篇
  1991年   1569篇
  1990年   1196篇
  1989年   1335篇
  1988年   1125篇
  1987年   976篇
  1986年   1019篇
  1985年   830篇
  1984年   610篇
  1983年   579篇
  1982年   547篇
  1981年   419篇
  1980年   380篇
  1979年   344篇
  1978年   359篇
  1977年   425篇
  1975年   304篇
  1972年   329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.
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