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   5010215篇
  免费   396738篇
  国内免费   16022篇
耳鼻咽喉   71614篇
儿科学   158499篇
妇产科学   133783篇
基础医学   747420篇
口腔科学   143351篇
临床医学   455813篇
内科学   912781篇
皮肤病学   116896篇
神经病学   422124篇
特种医学   199402篇
外国民族医学   1270篇
外科学   754588篇
综合类   147610篇
现状与发展   23篇
一般理论   2884篇
预防医学   422824篇
眼科学   119913篇
药学   357820篇
  24篇
中国医学   12831篇
肿瘤学   241505篇
  2021年   56412篇
  2019年   59029篇
  2018年   75160篇
  2017年   57499篇
  2016年   64171篇
  2015年   76822篇
  2014年   111733篇
  2013年   177228篇
  2012年   137684篇
  2011年   144435篇
  2010年   129136篇
  2009年   130172篇
  2008年   131448篇
  2007年   140458篇
  2006年   148759篇
  2005年   143355篇
  2004年   144367篇
  2003年   134256篇
  2002年   124743篇
  2001年   190680篇
  2000年   188752篇
  1999年   170742篇
  1998年   75984篇
  1997年   71118篇
  1996年   68998篇
  1995年   64793篇
  1994年   58876篇
  1993年   54626篇
  1992年   129662篇
  1991年   124666篇
  1990年   119728篇
  1989年   116402篇
  1988年   108251篇
  1987年   106617篇
  1986年   101400篇
  1985年   98983篇
  1984年   80828篇
  1983年   71368篇
  1982年   53424篇
  1981年   49330篇
  1980年   46403篇
  1979年   73398篇
  1978年   56994篇
  1977年   49703篇
  1976年   46460篇
  1975年   46662篇
  1974年   54030篇
  1973年   51898篇
  1972年   48609篇
  1971年   44982篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Carbon monoxide (CO), a byproduct of heme catalysis, was shown to have potent cytoprotective and anti-inflammatory effects. In vivo recipient CO inhalation at low concentrations prevented ischemia/reperfusion (I/R) injury associated with small intestinal transplantation (SITx). This study examined whether ex vivo delivery of CO in University of Wisconsin (UW) solution could ameliorate intestinal I/R injury. Orthotopic syngenic SITx was performed in Lewis rats after 6 h cold preservation in control UW or UW that was bubbled with CO gas (0.1-5%) (CO-UW). Recipient survival with intestinal grafts preserved in 5%, but not 0.1%, CO-UW improved to 86.7% (13/15) from 53% (9/17) with control UW. At 3 h after SITx, grafts stored in 5% CO-UW showed improved intestinal barrier function, less mucosal denudation and reduced inflammatory mediator upregulation compared to those in control UW. Preservation in CO-UW associated with reduced vascular resistance (end preservation), increased graft cyclic guanosine monophosphate levels (1 h), and improved graft blood flow (1 h). Protective effects of CO-UW were reversed by ODQ, an inhibitor of soluble guanylyl cyclase. In vitro culture experiment also showed better preservation of vascular endothelial cells with CO-UW. The study suggests that ex vivo CO delivery into UW solution would be a simple and innovative therapeutic strategy to prevent transplant-induced I/R injury.  相似文献   
942.
943.
944.
芦荟自古就被用作化妆品和药物添加剂,近来更受喜爱。虽应用广泛,但过敏反应罕有报道。作者用芦荟叶的油性提取物、来自整个植株的芦荟粉及浓缩的芦荟凝胶,对相继就诊的702例患者做斑贴试验。设计专门的问卷调查芦荟的使用、使用原因、使用部位、不良反应、患者职业、个人爱好及是否为遗传性过敏体质。患者均未对任一制剂发生任何反应。需对芦荟所含的两种成分加以鉴别:即芦荟叶皮含有的具有促进肠蠕动、潜在抗菌及抗癌特性的蒽醌类物质。  相似文献   
945.
946.
The absence of the temporary incisors could be to a genetic illness or to some multiple premature extractions. These extractions are the aftermaths of the carious lesions or some traumatisms underwent by the temporary incisors. Beyond measure the loss of the space, the premature loss some temporary incisors very often assign the relational development of the child and disturb its psychological development and the aesthetic function. Across some cases clinics, the authors show that the replacement of the temporary incisors is the therapeutic ideal solution. Indeed, the child prosthesis, replacing the temporary absent incisors, solves the psychological, aesthetic and relational problems of the child.  相似文献   
947.
The onset of the sporadic Creutzfeldt-Jakob disease is usually characterized by dementia or neurological symptoms. We are reporting the case of a 31 year-old man with a sporadic Creutzfeldt-Jakob disease characterized by a schizophrenia-like onset. The schizophrenic symptoms developed for sixteen months before the neurological symptoms appeared. The psychiatric onset of the present case was linked with the early age of onset and the long duration of the disease and could have been influenced by polymorphism of the codon 129 of the prion protein gene (PRNP) and a type of pathological prion protein (PrPres).  相似文献   
948.
Bifid mandibular canal.   总被引:1,自引:0,他引:1  
PURPOSE: To determine the incidence and characteristics of bifid mandibular canals. METHODS: A retrospective study was performed using panoramic radiographs of 2012 patients subjected to dental treatment in the Dental Clinic of the Valencia University Dental School (Valencia, Spain) between 1996 and 1999. The goal was to investigate the presence of double mandibular canals. RESULTS: The extraoral panoramic radiographs revealed a total of 7 images suggestive of bifid canals. Mandibular computed tomography revealed the existence of this anatomic variant in 2 of 3 patients. An analysis was performed on the incidence of this type of image in extraoral panoramic radiography, its possible interpretations, and the clinical implications of bifid mandibular canals. CONCLUSIONS: In this study, 0.35% of canals were bifid. All cases were in women.  相似文献   
949.
950.
目的探讨超短波对坐骨神经损伤后大鼠脊髓中GAP-43和CGRP表达的影响。方法60只成年雌性SD大鼠制成右侧坐骨神经钳夹损伤模型,随机分为超短波治疗组和非治疗对照组。免疫荧光方法观察术后1周、2周、4周、8周和12周不同时间点两组大鼠脊髓中GAP-43和CGRP表达的动态变化规律。结果大鼠坐骨神经损伤后脊髓内GAP-43和CGRPmRNA表达增强。术后1、2、4和8周超短波治疗组的变化与对照组比较差异有统计学意义(P〈0.05),且GAP-43的表达在时间上早于对照组。结论超短波在早期能够明显增加GAP-43和CGRP的表达量,提示早期应用超短波治疗能够促进周围神经的  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