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   4852篇
  免费   430篇
  国内免费   34篇
耳鼻咽喉   27篇
儿科学   67篇
妇产科学   65篇
基础医学   1141篇
口腔科学   42篇
临床医学   450篇
内科学   304篇
皮肤病学   28篇
神经病学   485篇
特种医学   106篇
外科学   233篇
综合类   733篇
预防医学   987篇
眼科学   156篇
药学   328篇
  11篇
中国医学   79篇
肿瘤学   74篇
  2024年   10篇
  2023年   69篇
  2022年   198篇
  2021年   258篇
  2020年   232篇
  2019年   151篇
  2018年   177篇
  2017年   177篇
  2016年   215篇
  2015年   221篇
  2014年   390篇
  2013年   557篇
  2012年   283篇
  2011年   342篇
  2010年   259篇
  2009年   261篇
  2008年   286篇
  2007年   243篇
  2006年   223篇
  2005年   156篇
  2004年   116篇
  2003年   124篇
  2002年   86篇
  2001年   60篇
  2000年   55篇
  1999年   42篇
  1998年   28篇
  1997年   21篇
  1996年   17篇
  1995年   7篇
  1994年   2篇
  1993年   6篇
  1992年   8篇
  1991年   3篇
  1990年   3篇
  1989年   8篇
  1988年   1篇
  1987年   4篇
  1986年   3篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1982年   3篇
  1980年   1篇
  1978年   3篇
  1977年   1篇
  1974年   1篇
  1973年   2篇
排序方式: 共有5316条查询结果,搜索用时 7 毫秒
1.
2.
3.
Retinal fundus photographs are employed as standard diagnostic tools in ophthalmology. Serial photographs of the flow of fluorescein and indocyanine green (ICG) dye are used to determine the areas of the retinal lesions. For objective measurements of features, the registration of the images is a necessity. In this paper, we employ optimization techniques for registration with the help of 2-parameter translational motion model of retinal angiograms, based on non-linear pre-processing (Wiener filtering and morphological gradient) and computation of the similarity criteria for the alignment of the two gradient images for any given rigid transformation. The optimization methods are effectively employed to minimize the similarity criterion.

The presence of noise, the variations in the background and the temporal variation of the fluorescence level pose serious problems in obtaining a robust registration of the retinal images. Moreover, local search strategies are not robust in the case of ICG angiograms, even if one uses a multiresolution approach.

The present work makes a systematic comparison of different optimization techniques, namely the minimization method derived from the optical flow formulation, the Nelder-Mead local search and the HCIAC ant colony metaheuristic, each optimizing a similarity criterion for the gradient images. The impact of the resolution and median filtering of gradient image is studied and the robustness of the approaches is tested through experimental studies, performed on macular fluorescein and ICG angiographies.

Our proposed optimization techniques have shown interesting results especially for high resolution difficult registration problems. Moreover, this approach seems promising for affine (6-parameter motion model) or elastical registrations.  相似文献   

4.
大学生网络成瘾量表的初步编制   总被引:1,自引:0,他引:1  
目的编制可供评估网络成瘾倾向的自评量表。方法采用自编《大学生网络成瘾量表》为研究工具对197名在校大学生为被试进行测试。结果①初步编制的《大学生网络成瘾量表》共46条目,包括2个分量表:网络成瘾倾向和网络成瘾类型分量表,其中网络成瘾倾向分量表分为成瘾症状成分(即成瘾症状、消极影响2个维度)和认知、情感体验成分(即内心体验、自我认知2个维度);网络成瘾类型分为网络关系成瘾、网络娱乐成瘾、信息搜集成瘾和网络性成瘾4个维度;②本量表具有较好的信度:成瘾倾向分量表及各维度的同质性信度为0·80~0·95,网络成瘾类型分量表为0·78,符合测量学标准;网络成瘾倾向分量表及各维度的重测信度除消极影响为0·67外,其他为0·75~0·88,网络成瘾类型分量表为0·74,也都基本达到心理测量学标准;③本量表成瘾倾向分量表的成瘾标志和消极影响维度与陈淑惠《中文网络成瘾量表》各个因子以及总分的相关(0·78~0·83)均显示有统计学意义,说明其具有良好的结构效度。结论该量表评价内容范围较宽、提供信息量较大,题目量适中,并且其信、效度较好,为后续研究打下了良好基础。  相似文献   
5.
Research has shown that increasing numbers of teenagers are going online to find health information, but it is unclear whether there are disparities in the prevalence of online health seeking among young Internet users associated with social and economic conditions. Existing literature on Internet uses by adults indicates that low income, less educated, and minority individuals are less likely to be online health seekers. Based on the analysis of data from the Pew Internet and American Life Project for the US, this study finds that teens of low education parents are either as likely as or even more likely than teens of high education parents to seek online health information. Multiple regression analysis shows that the higher engagement in health seeking by teens of low education parents is related to a lower prevalence of parental Internet use, suggesting that some of these teens may be seeking online health information on behalf of their low education parents. Implications of these findings are discussed in relation to the issues of the digital divide and digital empowerment.  相似文献   
6.
OBJECTIVE: To evaluate the user experience and acceptability of an electronic patient monitoring system. SETTING AND PARTICIPANTS: 822 Military and civilian personnel at a health clinic at a major US military headquarters used an Internet and telephone-based electronic monitoring system to report vaccination-site responses and symptoms after receiving the smallpox vaccination. Focus groups of vaccinees were conducted to help develop a survey about the experience that was distributed to 379 vaccinees (96% completion rate). RESULTS: Users of the electronic monitoring system reported that it was fast and easy to use and reported they would use a system like this again and recommend an electronic monitoring system to a friend or relative. Most users (84%) were comfortable with a physician tracking their vaccine reaction using their electronic reports, but only half (51%) were comfortable with eliminating the post-vaccination follow-up visit with their health-care provider based on their electronic reports. CONCLUSIONS: This electronic monitoring system was well received by vaccinees and allowed health-care providers to track the status of vaccinees. However, vaccinees were not comfortable replacing a physician visit with electronic monitoring, at least for the smallpox vaccination. A monitoring system like this may be useful in public health settings, such as mass vaccination or prophylaxis during a bioterrorism event, a pandemic influenza outbreak, or another public health emergency.  相似文献   
7.
本系统通过以Internet网为平台,将传统的医院/患者(咨询者)的遗传随访模式转为医院/Internet网/患者(咨询者)的新医疗模式,该系统会大大提高遗传随访的及时性和便利性;同时,会有利于遗传登记的开展,也有利于随访资料的保存。  相似文献   
8.
互联网与中医学教育   总被引:1,自引:0,他引:1  
随着网络技术的飞速发展,互联网对中医学教育产生深远的影响。传统的中医学教育模式正面临着网络技术带来的冲击,文章提出了中医学教育应逐渐把以课堂教授为主的方式转向以网络互动式自学方式的观点。  相似文献   
9.
非期刊文献的网上检索   总被引:1,自引:0,他引:1  
介绍Internet上有关专利、标准、会议录、学位论文、科技报告等非期刊文献信息资源。  相似文献   
10.
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