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   16789篇
  免费   2194篇
  国内免费   153篇
耳鼻咽喉   62篇
儿科学   70篇
妇产科学   20篇
基础医学   415篇
口腔科学   14475篇
临床医学   403篇
内科学   788篇
皮肤病学   169篇
神经病学   65篇
特种医学   173篇
外科学   396篇
综合类   999篇
预防医学   798篇
眼科学   8篇
药学   226篇
  6篇
中国医学   25篇
肿瘤学   38篇
  2023年   467篇
  2022年   404篇
  2021年   724篇
  2020年   760篇
  2019年   811篇
  2018年   705篇
  2017年   739篇
  2016年   724篇
  2015年   705篇
  2014年   1000篇
  2013年   1050篇
  2012年   802篇
  2011年   829篇
  2010年   636篇
  2009年   639篇
  2008年   628篇
  2007年   615篇
  2006年   561篇
  2005年   518篇
  2004年   470篇
  2003年   464篇
  2002年   381篇
  2001年   349篇
  2000年   293篇
  1999年   258篇
  1998年   251篇
  1997年   270篇
  1996年   259篇
  1995年   206篇
  1994年   169篇
  1993年   179篇
  1992年   216篇
  1991年   172篇
  1990年   166篇
  1989年   162篇
  1988年   170篇
  1987年   141篇
  1986年   140篇
  1985年   145篇
  1984年   106篇
  1983年   95篇
  1982年   88篇
  1981年   83篇
  1980年   97篇
  1979年   82篇
  1978年   68篇
  1977年   81篇
  1976年   71篇
  1975年   58篇
  1974年   66篇
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
71.
The treatment times for the fabrication of Extensive Amalgam Restorations (EAR) as recorded in a longitudinal clinical trial at the Dental School in Nijmegen were analyzed. 269 EAR's with different retention methods were made on molars by three operators. A mean total treatment time of 60 min was found. The factor operator had a significant influence on all treatment phases resulting in a 26% difference in total treatment time between operators. Also significant influences were found in some treatment phases for the factor retention, side location of the tooth and extension of the restoration. The results of this study with regard to treatment times must be considered from the perspective of the quality of the care provided.  相似文献   
72.
纤维连接蛋白对生物矿化影响的体外实验研究   总被引:1,自引:0,他引:1  
目的:探讨纤维连接蛋白(Fn)对生物矿化过程的影响,为其应用于临床作盖髓剂提供理论依据.方法:应用体外凝胶矿化系统结合微观形态学观察,研究有无羟基磷灰石(HAP)晶核时Fn对钙磷沉积的影响.结果:凝胶体系中随Fn浓度升高,吸光度值也升高(P<0.01),表明磷酸钙沉淀量的增多;加入HAP并不降低Fn的促沉积活性.结论:Fn可能通过促进钙磷沉积及其与HAP的相互作用参与矿化过程,此特性可能有利于Fn作为盖髓剂成份诱导牙本质桥形成.  相似文献   
73.
目的:研究VitapanClassical比色板各比色片中1/3部分的色度值的分布规律,以利于提高临床上的比色准确率。方法:在自然光线下用数码相机对VitapanClassical比色板进行摄影,将拍摄结果输入计算机,经Photoshop7.0软件处理后,记录各比色片中1/3部分的亮度和RGB值。结果:各比色片中1/3部分的亮度和R、G、B值是不同的。结论:数码摄影能够较真实地再现VitapanClassical比色片的颜色,可以作为临床比色方法和烤瓷材料颜色选择的补充。  相似文献   
74.
75.
作者通过内窥镜对新疆奎屯地区氟中毒患者35名,氟砷中毒患者32名,对照组25名的胃粘膜进行观察,旨在了解氟元素和砷元素对胃粘膜的影响,在3个组中慢性胃炎的炎症程度与炎症活动性有显著性差异。2个中毒组间无显著性差异。结果表明在高氟区和高氟砷区患者的胃粘膜层病理改变主要是任性氟中毒引起,单纯性砷中毒并无协同作用。  相似文献   
76.
本文应用 Mop-Videoplan 图象分析仪对氟中毒家猪胫骨进行了骨计量学的初步研究。四环素双标记后将家猪胫骨制备成骨磨片,在荧光及普通光学显微镜下测量了一系列骨计量学参数。结果表明,氟中毒导致家猪胫骨髓腔面皮质新骨体积明显增加,但其增加程度不与血氟呈正相关。新骨体积增加可能是造成临床 X 线氟骨症表现骨髓腔狭窄的原因。骨动力学研完表明,氟中毒造成四环素双标记明显减少,这可能与氟抑制骨组织的转换过程有关。  相似文献   
77.
Difficulties with tooth protectors in endotracheal intubation   总被引:1,自引:0,他引:1  
The suitability of three tooth protectors for routine use during endotracheal intubation was studied in 300 consecutive patients undergoing elective operations under general anaesthesia. The main disadvantages of the protectors were lack of space and the consequent difficulty of guiding the endotracheal tube into the larynx, and poor visibility, especially when the Camo protector was used. These difficulties could be avoided in most cases by cutting off the right angle of the Camo protector. The less experienced anaesthesiologists especially had difficulties with the protectors: 20% of patients in the Camo group were considered impossible to intubate unless the protector was removed. The silicone inlay of the Camo protector melts and becomes adhesive at body temperature, which makes its prolonged use hazardous. Two patients lost a maxillary incisor despite the proper use of a protector (Denex). Thus the use of a tooth protector alone does not guarantee avoidance of dental trauma. Better results could be obtained by improving the design of the protectors and by careful pre-anaesthetic dental examination.  相似文献   
78.
This paper explores some modern concepts of teaching and learning, including cognitive theory, the zone of proximal development, constructivism, andragogy and learning styles and describes how they have informed the development of an undergraduate orthodontic curriculum. The changes described include student-centred learning, guided self-learning, and the incorporation of problem-based learning concepts. The details of the problem-based learning programme are described together with results of student feedback on the change in teaching and learning style.  相似文献   
79.
继发性骨质疏松防治的研究   总被引:2,自引:1,他引:1  
目的总结继发性骨质疏松预防与治疗的经验及提出见解.方法用钙代谢平衡的方法研究了钙代谢的基本情况,比较了补钙与不补钙在若干种生理状态对骨密度的影响,总结继发性骨质疏松的病因及对其采取不同方法的治疗经验.结果中国人膳食含钙量属于正常范围低水平状态,与适宜摄入量(AI)比较是不足的,在一定的生理状态下应予补钙.缺钙是原发性骨质疏松与继发性骨质疏松的不利因素.氟中毒骨病、糖尿病、性腺功能减退、肿瘤、糖皮质激素过多和甲亢均有其各别的病理生理,导致继发性骨质疏松,防治方法各异.结论从胚胎至老年都应防治骨质疏松.不同情况采取方法各异,但有效.  相似文献   
80.
Abstract –  The aims of this study were to analyze the histomorphology of developing permanent teeth whose primary teeth had suffered traumatic intrusion, as well as to compare the influence of immediate extraction of the intruded tooth to passive re-eruption. Nine dogs from 45 to 50 days old were submitted to the intrusion of the maxillary central and lateral primary incisors using a force applicator adapted to the teeth incisal cuspids. The right side intruded teeth were kept in their sockets and the ones on the left side were extracted 30 min later. After a postoperatory periods of 30 and 60 days, four (group 1) and five (group 2) dogs, respectively, were killed by perfusion. The histological evaluations showed that, in group 1, alterations had occurred in the odontoblastic layer and deposition of the enamel matrix had taken place in some specimens while in group 2, a portion of non-mineralized matrix was observed. We concluded that the morphological changes were because of the immediate trauma of intrusion. No differences were found between the groups where the primary tooth was immediately extracted or left to passively re-erupt.  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