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   210305篇
  免费   15212篇
  国内免费   749篇
耳鼻咽喉   2284篇
儿科学   5482篇
妇产科学   4304篇
基础医学   27105篇
口腔科学   4512篇
临床医学   19998篇
内科学   44885篇
皮肤病学   2755篇
神经病学   20307篇
特种医学   6951篇
外国民族医学   13篇
外科学   32928篇
综合类   3415篇
现状与发展   2篇
一般理论   291篇
预防医学   19068篇
眼科学   4373篇
药学   14389篇
  1篇
中国医学   374篇
肿瘤学   12829篇
  2023年   844篇
  2022年   1405篇
  2021年   3440篇
  2020年   2106篇
  2019年   3394篇
  2018年   3971篇
  2017年   3212篇
  2016年   3413篇
  2015年   4066篇
  2014年   6096篇
  2013年   8824篇
  2012年   13125篇
  2011年   14320篇
  2010年   8096篇
  2009年   7304篇
  2008年   13588篇
  2007年   14425篇
  2006年   13918篇
  2005年   14392篇
  2004年   13808篇
  2003年   12899篇
  2002年   12437篇
  2001年   1874篇
  2000年   1458篇
  1999年   2045篇
  1998年   2829篇
  1997年   2437篇
  1996年   2205篇
  1995年   1953篇
  1994年   1755篇
  1993年   1655篇
  1992年   1208篇
  1991年   1149篇
  1990年   1055篇
  1989年   956篇
  1988年   1014篇
  1987年   1019篇
  1986年   1001篇
  1985年   1082篇
  1984年   1481篇
  1983年   1461篇
  1982年   1814篇
  1981年   1639篇
  1980年   1555篇
  1979年   812篇
  1978年   958篇
  1977年   932篇
  1976年   831篇
  1975年   682篇
  1974年   666篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
1.
2.
OBJECTIVE: A series of nasopharyngeal appliance designs is presented that represents our evolving experience over a 20-year period in the adjunctive use of prosthetic stents in the surgical correction of nasopharyngeal stenosis. DESIGN: Retrospective assessment of effectiveness of two nasopharyngeal stenosis hollow stent designs in a consecutive series of patients for relief of nasal obstructive symptoms. SETTING: Tertiary academic medical center, Craniofacial Program at Children's Hospital. PATIENTS: Four patients with nasopharyngeal stenosis were treated with a preoperatively fabricated stent made from a clasped palatal appliance onto which hollow acrylic conduits were extended through surgically re-created pharyngeal ports. A subsequent set of four patients with nasopharyngeal stenosis were treated with intraoperatively-fashioned silastic grommets, as opposed to palatal appliances. INTERVENTIONS: Postoperative intraoral stenting of nasopharyngeal ports. MAIN OUTCOME MEASURES: Maintenance of pharyngeal port opening after 1 year, improvement in nasal airway obstructive symptoms. RESULTS: The palatal appliance stents were less well tolerated and had a lower maintenance of port patency after device removal (4 of 8, 50%). The silastic grommets provided better retention into the ports and increased patient tolerance, as well as better 1-year port maintenance (6 of 8, 75%). CONCLUSIONS: The grommet stent appliance offers numerous advantages over a conventional dental-clasped appliance for prosthetic nasopharyngeal stenting, including obviation of extensive preoperative preparation, ease of insertion and removal, and exchange of air during the stenting period. Improved nasopharyngeal patency with this device may be due to greater patient tolerance and subsequent longer use.  相似文献   
3.
4.
OBJECTIVE: To illustrate the safety and efficacy of the endoscopic laser approach for cricopharyngeal myotomy (CPM) compared to the traditional transcervical approach. STUDY DESIGN AND SETTING: Retrospective chart review of 22 patients undergoing CPM from 1996 to 2003 at the Mayo Clinic, Jacksonville. RESULTS: The laser CPM technique was used in 14 patients, and an open approach in 8. The mean hospital stay and operative times were shorter for the laser group. Functional outcome analyses showed improvement in both groups. There were no major complications in the laser group, while 1 patient in the transcervical group had a pharyngocutaneous fistula. CONCLUSIONS: The laser technique is at least as effective as the transcervical approach for CPM to improve dysphagia symptoms in the properly selected patient, with a low risk of major complications. SIGNIFICANCE: In this report, we provide the reader with data to support the safety and efficacy of laser CPM. EBM rating: B-3b.  相似文献   
5.
6.
7.
B.  Greg  Brown  John  Growley  宋善俊 《美国医学会杂志》2006,25(2):124-126
过去15年来,有关动脉粥样硬化的流行病学、基础生物学和实验研究均支持下述假设:抗氧化剂可通过抑制动脉壁低密度脂蛋白的氧化而抑制动脉粥样硬化的发生。这种作用机制可抑制胆固醇酯通过巨噬细胞清除受体在动脉斑块内发生病理性沉积。胆固醇酯病理沉积是一种可引起斑块破裂及心血管事件的过程。同样,生物机制亦已确定,癌基因可被抗氧化剂阻断。  相似文献   
8.
9.
Over 100 mutations in the presenilin‐1 gene (PSEN1) have been shown to result in familial early onset Alzheimer disease (EOAD), but only a relatively few give rise to plaques with an appearance like cotton wool (CWP) and/or spastic paraparesis (SP). A family with EOAD, seizures and CWP was investigated by neuropathological study and DNA sequencing of the PSEN1 gene. Aβ was identified in leptomeningeal vessels and in cerebral plaques. A single point mutation, p.L420R (g.1508T > G) that gives rise to a missense mutation in the eighth transmembrane (TM8) domain of PS1 was identified in two affected members of the family. p.L420R (g.1508T > G) is the mutation responsible for EOAD, seizures and CWP without SP in this family.  相似文献   
10.
We report the MRI features in a series of four patients with primary angiitis of the central nervous system (PACNS). Based on MRI features, clinical presentation, paraclinical investigations and laboratory tests, including cerebrospinal fluid (CSF) analysis, various differentials were considered. In two patients with MRI findings of cortical, subcortical and deep white matter lesions, lack of mass effect, focal areas of bleed and heterogeneous parenchymal, leptomeningeal or pial enhancement and a normal magnetic resonance angiography, a differential diagnosis of primary angiitis of the CNS was also considered. In all patients, an open brain biopsy was advised to establish a definitive diagnosis of PACNS. Here, we briefly discuss the MRI features, correlation with clinical presentation and paraclinical parameters for the diagnosis of this entity. We also briefly review the literature.  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