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   3606篇
  免费   73篇
  国内免费   94篇
教育   1454篇
科学研究   958篇
体育   58篇
综合类   118篇
文化理论   2篇
信息传播   1183篇
  2023年   21篇
  2022年   44篇
  2021年   73篇
  2020年   120篇
  2019年   152篇
  2018年   103篇
  2017年   116篇
  2016年   109篇
  2015年   165篇
  2014年   338篇
  2013年   367篇
  2012年   335篇
  2011年   321篇
  2010年   175篇
  2009年   167篇
  2008年   193篇
  2007年   200篇
  2006年   178篇
  2005年   153篇
  2004年   108篇
  2003年   84篇
  2002年   96篇
  2001年   67篇
  2000年   36篇
  1999年   13篇
  1998年   8篇
  1997年   4篇
  1996年   1篇
  1995年   4篇
  1994年   3篇
  1993年   3篇
  1992年   6篇
  1991年   5篇
  1989年   1篇
  1981年   1篇
  1957年   3篇
排序方式: 共有3773条查询结果,搜索用时 15 毫秒
81.
Queries submitted to search engines can be classified according to the user goals into three distinct categories: navigational, informational, and transactional. Such classification may be useful, for instance, as additional information for advertisement selection algorithms and for search engine ranking functions, among other possible applications. This paper presents a study about the impact of using several features extracted from the document collection and query logs on the task of automatically identifying the users’ goals behind their queries. We propose the use of new features not previously reported in literature and study their impact on the quality of the query classification task. Further, we study the impact of each feature on different web collections, showing that the choice of the best set of features may change according to the target collection.  相似文献   
82.
设计索引的目的是为了加快数据检索.文章就与索引相关的一些特征元素.提出了创建索引中数据目录项的3种不同方法.同时对B^ 索引进行了描述.分析了其在进行数据搜索的实现原理.简要个绍了在实现数据删除和插入时的优化思路.  相似文献   
83.
网络教育资源搜索策略研究   总被引:2,自引:0,他引:2  
将网络教育手段运用于课堂教学中,是教育科研的一个新课题。用好网上教育资源的关键是根据教学科研目的,学会灵活设计检索策略获取资源,将其有机地应用于教学和科研。  相似文献   
84.
随着移动通信技术的发展和智能手机的普及,利用手机延伸图书馆服务越来越受到人们的关注,手机图书馆便应运而生。当下,在高校手机图书馆大发展的浪潮中,针对存在的各种问题,需要加强手机图书馆普及力度,构建门户网站,同时发挥图书馆联盟的作用,保护好知识产权。  相似文献   
85.
现今电脑硬盘的容量越来越大,其中储存的文件也越来越多.开发能够实现文件快速查找功能的应用程序,必将具有广泛的应用前景.利用VB6.0提供的强大文件操作对象(File System Object),编制了几种切实可行的文件快速查找程序.  相似文献   
86.
针对非完整移动机器人的轨迹重复跟踪问题,提出了一种开环P型迭代学习控制算法。首先给出非完整移动机器人的运动学模型,并结合离散时域对轨迹跟踪问题进行描述,然后设计迭代学习控制器并在给定条件下证明了其收敛性;MATLAB仿真结果表明,随着迭代次数的增加,该算法能够有效改善动态不确定环境中系统的稳定性与收敛的快速性。  相似文献   
87.
运用三角形的Fermat问题的结论与两个条件不等式,利用导数,证明了涉及平面上任一点到三角形三顶点距离之和的一个最佳线性不等式,提出了一个相关的问题.  相似文献   
88.
This paper reports on two studies which investigated the relationship between children's texting behaviour, their knowledge of text abbreviations and their school attainment in written language skills. In Study One, 11–12‐year‐old children provided information on their texting behaviour. They were also asked to translate a standard English sentence into a text message and vice versa. The children's standardised verbal and non‐verbal reasoning scores were also obtained. Children who used their mobiles to send three or more text messages a day had significantly lower scores than children who sent none. However, the children who, when asked to write a text message, showed greater use of text abbreviations (‘textisms’) tended to have better performance on a measure of verbal reasoning ability, which is highly associated with Key Stage 2 (KS2) and 3 English scores. In Study Two, children's performance on writing measures was examined more specifically. Ten to eleven‐year‐old children were asked to complete another English to text message translation exercise. Spelling proficiency was also assessed, and KS2 Writing scores were obtained. Positive correlations between spelling ability and performance on the translation exercise were found, and group‐based comparisons based on the children's writing scores also showed that good writing attainment was associated with greater use of textisms, although the direction of this association is nor clear. Overall, these findings suggest that children's knowledge of textisms is not associated with poor written language outcomes for children in this age range.  相似文献   
89.
随着移动通信技术的迅速发展,高校开展手机图书馆服务已经成为一种趋势。通过问卷,调查了合肥市7所高校的读者和馆员对手机图书馆服务的需求现状。并对调查结果进行了分析讨论,探究合肥市高校开展手机图书馆服务的可行性,指出了存在的问题并给出相关建议。  相似文献   
90.
When searching for health information, results quality can be judged against available scientific evidence: Do search engines return advice consistent with evidence based medicine? We compared the performance of domain-specific health and depression search engines against a general-purpose engine (Google) on both relevance of results and quality of advice. Over 101 queries, to which the term ‘depression’ was added if not already present, Google returned more relevant results than those of the domain-specific engines. However, over the 50 treatment-related queries, Google returned 70 pages recommending for or against a well studied treatment, of which 19 strongly disagreed with the scientific evidence. A domain-specific index of 4 sites selected by domain experts was only wrong in 5 of 50 recommendations. Analysis suggests a tension between relevance and quality. Indexing more pages can give a greater number of relevant results, but selective inclusion can give better quality.  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