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   14764篇
  免费   1975篇
  国内免费   622篇
耳鼻咽喉   85篇
儿科学   120篇
妇产科学   188篇
基础医学   1914篇
口腔科学   529篇
临床医学   1690篇
内科学   1804篇
皮肤病学   125篇
神经病学   1784篇
特种医学   573篇
外国民族医学   13篇
外科学   1058篇
综合类   2504篇
现状与发展   5篇
预防医学   1591篇
眼科学   157篇
药学   1153篇
  28篇
中国医学   1369篇
肿瘤学   671篇
  2024年   169篇
  2023年   623篇
  2022年   1125篇
  2021年   1536篇
  2020年   1270篇
  2019年   824篇
  2018年   619篇
  2017年   560篇
  2016年   558篇
  2015年   630篇
  2014年   947篇
  2013年   1041篇
  2012年   836篇
  2011年   882篇
  2010年   746篇
  2009年   638篇
  2008年   693篇
  2007年   625篇
  2006年   568篇
  2005年   466篇
  2004年   337篇
  2003年   304篇
  2002年   208篇
  2001年   142篇
  2000年   142篇
  1999年   126篇
  1998年   138篇
  1997年   126篇
  1996年   84篇
  1995年   91篇
  1994年   73篇
  1993年   47篇
  1992年   33篇
  1991年   27篇
  1990年   26篇
  1989年   19篇
  1988年   12篇
  1987年   2篇
  1986年   16篇
  1985年   11篇
  1984年   4篇
  1983年   5篇
  1982年   9篇
  1981年   5篇
  1980年   7篇
  1979年   2篇
  1978年   4篇
  1977年   3篇
  1976年   1篇
  1973年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
随着网络信息技术的发展,数字化、网络化信息资源的开发与利用迅速普及,高校图书馆的功能也发生显著的变化:以印刷文献为中心向以数字信息为中心转变;由单一化服务向多样化服务转变;由人工服务向智能化控制转变;由传统的图书存贮、借阅中心将发展成为现代化信息的交流中转站或导航站。本文分析和阐述了网络环境下高校图书馆功能的嬗变特点和规律,提出了具有实践意义的应对策略。  相似文献   
62.
网络和现实社会交互环境对网民的健康效应及卫生策略   总被引:1,自引:1,他引:0  
网络社会对人类社会活动和生活方式带来了极大的影响,对人群健康的作用也存在双重效应。网络成瘾、网络孤独以及生理损伤成为网络社会的主要健康问题,但提高网民社会化程度、提供虚拟支持、增加健康信息供给的途径也给网民带来了诸多的健康效益。目前,要积极制定网络社会卫生策略,以促进网络社会化、虚拟支持和网络健康赋权对网民健康的贡献。  相似文献   
63.
目的:建立下颌第一磨牙三维有限元模型。方法:通过螺旋CT扫描的方法,利用Mimics、Geomagic Studio 7等图像处理软件,HyperMesh网格自动划分软件,通过特定的MSC.MARC有限元软件建立下颌第一磨牙三维有限元模型。结果:准确的建立了牙本质、牙釉质、髓腔、牙槽骨、牙周膜等组织形态的三维有限元模型。结论:本实验建模方法可行性强,方便快捷,具有良好的生物力学与几何力学相似性。为临床口腔医师提供了一种简捷而精确的有限元建模方法。  相似文献   
64.
以苏州七子山垃圾填埋场为背景,采用理论分析的方法,探讨山谷型垃圾填埋场合理的渗滤液收集系统的形式和定量计算方法。  相似文献   
65.
In this paper we propose a method for construction of feed-forward neural classifiers based on regularization and adaptive architectures. Using a penalized maximum likelihood scheme, we derive a modified form of the entropic error measure and an algebraic estimate of the test error. In conjunction with optimal brain damage pruning, a test error estimate is used to select the network architecture. The scheme is evaluated on four classification problems.  相似文献   
66.
The morphology and distribution of dopaminergic interplexiform cells in adult rat and monkey retinas were analyzed to determine any correlation with the function of dopamine in the outer retinal layers. The retinas were processed as whole mounts for tyrosine hydroxylase immunohistochemistry. There was a network formed by the sclerally directed processes of interplexiform cells in the inner nuclear, outer plexiform, and outer nuclear layers running throughout the retina. Their density was higher in the superior retina than in the inferior retina of the rat and was especially high in the superior temporal quadrant. The external network in this quadrant was significantly less dense in the monkey than in the rat, as are the interplexiform cells. The somata of interplexiform and other dopaminergic cells were about the same size in both rats and monkeys. Computer-assisted reconstruction of external arborizations of individual cells showed that external processes lay very close to horizontal and photoreceptor cells and also to blood capillaries. Because they were long, thin, and highly varicose; branched at right angles; and often arose from an axon hillock, the external processes were identified as axons. Therefore, we define the dopaminergic interplexiform cells as multiaxonal neurons, with at least one outwardly directed axon that reaches the outer plexiform layer. The function of the network of external processes from the interplexiform dopaminergic cells is discussed in terms of modulating the release of dopamine to external layers.  相似文献   
67.
This paper studies global bifurcation structure of the chaotic neural networks applied to solve the traveling salesman problem (TSP). The bifurcation analysis clarifies the dynamical basis of the chaotic neuro-dynamics which itinerates a variety of network states associated with possible solutions of TSP and efficiently ‘searches’ for the optimum or near-optimum solutions. By following the detailed merging process of chaotic attractors via crises, we find that the crisis-induced intermittent switches among the ruins of the previous localized chaotic attractors underly the ‘chaotic search’ for TSP solutions. On the basis of the present study, efficiency of the ‘chaotic search’ to optimization problems is discussed and a guideline is provided for tuning the bifurcation parameter value which gives rise to efficient ‘chaotic search’.  相似文献   
68.
Summary The sensitivity of the cochlea is dependent upon maintenance of a delicate homeostatic environment. One mechanism which participates in providing this environment is the autoregulation of cochlear blood flow. This autoregulation is ensured through the interaction of sympathetic, peptidergic and hemodynamic mechanisms. The current study demonstrates an adaptation that also participates in cochlear blood flow autoregulation. Specifically, an anterior inferior cerebellar arterial network is described and the relative contributions of each of its vessels to total cochlear blood flow is measured using laser Doppler flowmetry. The results show that each collateral vessel contributes to the blood supply of the cochlea and that reperfusion is accompanied by hyperemia. These findings suggest an adaptation that provides stable blood flow through redundancy and compensatory potential. Additionally, these observations have implications for experimental models of ischemia.  相似文献   
69.
真皮下血管网皮瓣修复感染创面的研究   总被引:2,自引:0,他引:2  
目的:探讨真皮下血管网皮瓣的抗菌能力和临床修复感染创面的应用。方法:以家猪为实验动物,在臀部两侧分别形成传统的岛状皮瓣和真皮下血管网岛状皮瓣,用细菌计数、吖啶橙荧光染色测定白细胞吞噬指数和白细胞内杀菌率等方法,进行对比。结果:真皮下血管网岛状皮瓣的抗菌力明显降低。 1989年起临床应用 5例,创面彻底清创后用吻合血管的真皮下血管网游离皮瓣修复,全部成活。结论:该皮瓣抗菌力虽低于传统皮瓣,但仍可用于修复感染创面。  相似文献   
70.
Ductus arteriosus aneurysm is rare in adults and preoperative diagnosis has not been usually done. We report 2 cases of adult type ductus arteriosus aneurysm. In both cases, 3D computed tomographic scanning showed a saccular aneurysm originating from the distal aortic arch toward the left pulmonary artery, which had a notching in the orifice of the aortic side. They were successfully treated surgically though one was a ruptured aneurysm to the left pulmonary artery. In these cases, 3D-CT scan was of great value in the preoperative diagnosis of the ductus arteriosus aneurysm.  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