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   16710篇
  免费   1421篇
  国内免费   361篇
耳鼻咽喉   629篇
儿科学   52篇
妇产科学   639篇
基础医学   913篇
口腔科学   506篇
临床医学   909篇
内科学   1332篇
皮肤病学   41篇
神经病学   137篇
特种医学   330篇
外国民族医学   1篇
外科学   885篇
综合类   2040篇
现状与发展   1篇
预防医学   375篇
眼科学   8619篇
药学   624篇
  6篇
中国医学   245篇
肿瘤学   208篇
  2024年   49篇
  2023年   284篇
  2022年   420篇
  2021年   714篇
  2020年   620篇
  2019年   538篇
  2018年   606篇
  2017年   612篇
  2016年   618篇
  2015年   528篇
  2014年   1041篇
  2013年   1058篇
  2012年   990篇
  2011年   1004篇
  2010年   878篇
  2009年   773篇
  2008年   770篇
  2007年   840篇
  2006年   708篇
  2005年   678篇
  2004年   579篇
  2003年   528篇
  2002年   450篇
  2001年   481篇
  2000年   313篇
  1999年   307篇
  1998年   231篇
  1997年   168篇
  1996年   144篇
  1995年   149篇
  1994年   105篇
  1993年   83篇
  1992年   93篇
  1991年   70篇
  1990年   58篇
  1989年   70篇
  1988年   46篇
  1987年   41篇
  1986年   49篇
  1985年   106篇
  1984年   112篇
  1983年   94篇
  1982年   116篇
  1981年   95篇
  1980年   105篇
  1979年   65篇
  1978年   74篇
  1977年   12篇
  1976年   7篇
  1975年   5篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
Purpose: Our purpose was to examine implantation of singleton pregnancies achieved following various assisted reproductive technologies (ARTs) through the appearance and rising titers of serum human chorionic gonadotropin (hCG) levels. Methods: A total of 114 singleton pregnancies resulting from in vitro fertilization and intrauterine insemination was analyzed. Patients were divided into five groups according to the type of ovarian stimulation protocol [gonadotropin stimulation with/without the use of gonadotropin-releasing hormone agonist (GnRHa), long protocol, or flare-up technique] and to the day of embryo transfer (day 2 or day 3 after oocyte retrieval). Serial serum hCG levels were measured between 10 and 25 days after fertilization and log-transformed. Linear regression analyses were performed and extrapolated to hCG = 10 mIU/ml (hCG 10 ), which was used as an estimate of detectable implantation. The slopes of the regression lines were used to estimate the rising speed of hCG. Results: There were no significant differences in the days of hCG in maternal serum to reach 10 mIU/ml (implantation) or in the slopes of the regression lines for all five studied groups. Conclusions: The appearance of hCG in maternal serum was used to assess the time of clinically detectable implantation. Furthermore, because hCG production is a marker of trophoblastic activity, its serum doubling time was used as an indicator of embryo quality. Results showed that in various ART protocols with and without GnRHa, there were no significant differences in implantation time or embryo quality. Embryo development in early pregnancy follows a preprogrammed-timing schedule and depends mainly on the embryonic age of the health, successfully implanted conceptus.  相似文献   
52.
Data regarding stent implantation for stenotic aortoarteriopathy (SAA) are incomplete. We report on nine patients with this rare syndrome who underwent arterial stent implantation. Indications, results, and complications for patients with SAA were reviewed. Nine patients underwent 11 procedures. Twenty-two stents were implanted in the aorta or brachiocephalic vessels. Five patients had diffuse stenoses, three patients had middle aortic syndrome, and one patient had thoracic and abdominal coarctation. Associated diagnoses included Williams syndrome (2), neurofibromatosis (2), Takayasu's (1), and congenital rubella (1). Median gradient was 60 mm Hg (20-140 mm Hg). Poststent gradient was 15 mm Hg (0-60 mm Hg; P < 0.001). Additional stents were implanted in two patients and five underwent stent redilation. Two patients (22%) were found to have aneurysm formation. Stent implantation effectively provides gradient relief in SAA. Gradient reduction persists or is amenable to redilation. Importantly, however, uncomplicated stent implantation does not preclude aneurysm formation and may be more common than in traditional patient groups.  相似文献   
53.
54.
55.
心脏瓣膜置换术后中远期疗效分析   总被引:8,自引:0,他引:8  
目的 分析探讨心脏瓣膜置换术的中远期疗效。方法  1978年至 2 0 0 1年 12月 ,行瓣膜置换手术 2 14 1例 ,同期随访 16 81例 ,计 80 2 1 1人·年 ,平均 4 77人·年。通过回顾病因、手术方式、瓣膜类型等因素 ,观察术后病人心功能改善情况 ,病死率及并发症等 ,采用t检验 ,多因素回归等统计学方法分析。结果  92例死亡。总体生存率 5年为 (92 3± 2 2 ) % ,10年生存率为 (90 1± 2 7) %。并发症有血栓栓塞、机械瓣膜功能障碍、瓣周漏、溶血、机械瓣膜感染性心内膜炎。术后心功能 (NYHA)与术前比较有明显的提高。结论  1.机械瓣置换术后中远期疗效满意 ,病死率及并发症均较低 ;与术前心功能和手术种类直接相关 ;2 .使用保留瓣下结构及三尖瓣成形术对术后心功能恢复有明显效果 ;3.术中良好心肌保护是提高手术成功率的关键。  相似文献   
56.
暂时性异位断足寄养再回植术   总被引:6,自引:2,他引:4  
目的:报道2例采用暂时性异位寄养再植技术,挽救无一期再植条件的新足及在特殊条件下的断足再植方法,方法,对无一期再植条件的2例断足,采用暂时异位寄养的方法,分别植于健侧小腿下段,分别利用胫后动脉和大隐静脉作为受区血管,维持断足存活,待全身状态平稳和离断肢体近端条件允许时,再将断足自寄养部位二期回植于原来的解剖位置。结果:2例断足完体成活。经4-6个月随访,受伤的下肢恢复正常长度,足底感受恢复,能下地行走。结论:暂时性异位寄养再植技术为挽救特殊条件下的离断肢体提供了一种新的选择,特殊条件下的断足和小腿下段的离断是暂时性异位寄养断肢再植术的理想病例。  相似文献   
57.
We compared the Acrysoft monofocal intraocular lens (IOL) in the mini monovision formula (n = 20) with the Array multifocal intraocular lens (n = 20) for glasses independence after cataract surgery. The Acrysoft monofocal IOL group showed similar and even slightly better results than the Array multifocal IOL group. The monofocal Acrysoft IOL using the mini monovision (blended vision) formula is a good alternative for providing post-cataract surgery glasses independence. Drs. Chen, Clinical Assistant Professor of Ophthalmology and Neal H. Atebara are at University of Hawaii School of Medicine, Honolulu, Hawaii, USA. Dr. Te Tsaw Chen, Past Professor & Director, was at Department of Ophthalmology, Taipei Medical University, Taipei, ROC. The authors have stated that they do not have a significant financial interest or other relationship with any product manufacturer or provider of services discussed in this article. The authors also do not discuss the use of off-label products, which includes unlabeled, unapproved, or investigative products or devices. The authors compared the Acrysoft monofocal intraocular lens in the mini monovision formula to the Array multifocal intraocular lens for glasses independence after cataract surgery.  相似文献   
58.
目的 :探讨右室心内膜永久性起搏电极植入术中 ,心尖部起搏与流入道起搏二者在术中起搏参数比较 ,以及流入道起搏电极植入方法。方法 :选择本院行永久性心脏起搏器安置术的 67例患者为研究对象 ,在右室心尖部起搏电极不易固定或测试起搏参数不理想时 ,改为右室流入道起搏 (12例 )。结果 :①右室心尖部及流入道两种位置起搏阈值、R波振幅、心肌阻抗比较无显著性差异 ;②术后随访 2~ 14个月两组病例均未发生电极脱位、感知异常、膈肌收缩。结论 :①右室流入道起搏与心尖部起搏一样是电极植入的有效部位 ;②右室流入道起搏与心尖部起搏一样心室电极植入技术简单易行  相似文献   
59.
通过对老年性白内障、外伤性白内障、先天性白内障(共14例)及正常晶体(20例)的SOD测定,表明晶体内自由基产生增加,抗氧化能力障碍是白内障形成的重要原因之一。同时,对晶体内自由基的发生及致病机理进行了探讨,提示在白内障形成初期,给予抗氧化制剂在可能阻止或延缓白内障形成。  相似文献   
60.
A 66-year-old man presented with bilateral subclavian steal syndrome (SSS) due to proximal subclavian artery occlusions. He was treated by percutaneous transluminal balloon angioplasty (PTA) and stent implantation in the left subclavian artery and by PTA alone in the right subclavian artery. We could demonstrate that interventional treatment of symptomatic bilateral SSS is possible. If PTA alone is insufficient, stent implantation should be considered.  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