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   2908篇
  免费   35篇
  国内免费   28篇
教育   2037篇
科学研究   271篇
体育   371篇
综合类   228篇
文化理论   1篇
信息传播   63篇
  2023年   4篇
  2022年   30篇
  2021年   25篇
  2020年   58篇
  2019年   38篇
  2018年   30篇
  2017年   33篇
  2016年   37篇
  2015年   73篇
  2014年   200篇
  2013年   217篇
  2012年   232篇
  2011年   251篇
  2010年   187篇
  2009年   147篇
  2008年   193篇
  2007年   206篇
  2006年   215篇
  2005年   187篇
  2004年   165篇
  2003年   147篇
  2002年   102篇
  2001年   89篇
  2000年   46篇
  1999年   22篇
  1998年   12篇
  1997年   7篇
  1996年   3篇
  1995年   1篇
  1994年   6篇
  1993年   3篇
  1992年   1篇
  1991年   1篇
  1979年   1篇
  1978年   2篇
排序方式: 共有2971条查询结果,搜索用时 15 毫秒
1.
社会快速发展、生活日趋便捷背景下,医学生面临着生理和心理上的问题,且医学生由于专业特殊性,认知能力中记忆力的重要性被凸显出来。本文运用查阅文献资料、专家访谈、问卷调查、逻辑分析等研究方法,探究从运动处方角度出发的实验--"高强度间歇运动对医学生不同时长记忆力的影响"具有多方面重要性。同时建议医学院校应当跟据研究结果和实际情况,制定科学、合理的运动训练计划,为医学生生理和心理健康提供保障。  相似文献   
2.
任务卸载是雾计算的主要技术之一,即计算能力不足的节点将任务卸载给具有富余资源的节点帮助计算。以优化任务平均卸载时延和提升卸载服务成功率为目标,利用多臂老虎机理论为动态雾计算网络提出一种基于在线学习的任务卸载算法,可实时做出最优卸载决策。将该算法扩展到非稳定网络状态,使之可以动态追踪网络中节点的资源与环境变化,实时调整卸载决策。详细分析所提出算法的性能、复杂度和存储占用情况。仿真结果表明,这两种算法可达到的长期平均任务卸载时延均十分接近理想算法下的最优时延,卸载服务成功率也得到显著提升。此外,所提算法在非稳定的网络状态下能够追踪到计算资源与环境的变化。  相似文献   
3.
Recent theories suggest that negative effects of fatigue on performance are determined by perception of effort and motivation rather than being directly caused by reaching physiological limits. In the current experiment, the influence of motivation on fatigue-induced decrements in soccer performance was experimentally investigated. Sixty amateur soccer players performed a validated soccer-passing test before and after a fatigue protocol. Results showed that players’ motivation and performance decreased after the fatigue protocol for players in the control group. In contrast, players in the motivation group (i.e., with motivation experimentally induced after the fatigue protocol) were able to uphold their motivation and increase their performance. These results indicate that motivation plays a crucial role in performance under fatigue, as fatigue-induced decrements in soccer passing performance can be counteracted by high levels of motivation. Future research may explore the limits of this counteracting effect and extend findings to other relevant performance aspects.  相似文献   
4.
为充分发掘分布在不同位置上的雾节点的计算资源,任务卸载被寄予众望。在雾计算场景下,以尽可能减少任务卸载的长期成本为目标,试图寻找一个高效的在线任务卸载方法。为此,这一问题被建模成一个随机规划问题,该问题中系统参数所对应的随机变量的期望会在未知时刻突变,系统参数相关信息只能在任务完成后的反馈中获得。基于非稳态多臂老虎机模型,提出一个高效的算法来解决这一具有挑战性的随机优化问题,给出理论分析证明该算法的渐进最优性。数值实验证明了该算法的优越性。  相似文献   
5.
吴继红 《软科学》2006,20(5):63-66
根据组织支持认知(Perce ived O rgan izational Support)和领导—成员交换(LeaderM ember Exchange)的研究,员工既与组织也与主管建立了社会交换关系。在借鉴国内外的相关理论的基础上,通过100对主管和员工的问卷调查验证了企业员工的组织支持认知对他们的任务绩效、组织公民行为和组织承诺有正向的影响;而企业员工的领导—成员交换认知对他们的组织公民行为有正向的影响。  相似文献   
6.
In the reconciliation of rational-choice and social-influence approaches to media choice offered here, the choice process is decomposed into two subprocesses. In the first subprocess—that of rational choice—decisional ambiguity frustrates complete optimization. Optimization is partial, yielding a set of effectively interchangeable media alternatives over which the user is indecisive. In the second subprocess—that of social influence—imitation, deference, and other cues act on the set of interchangeables, yielding a single ultimate choice. If in the social-influence subprocess there are benefits to coordinating with others, group choice crystallizes around a single media alternative. If these benefits are absent, individual choice remains idiosyncratic, with each decision maker making random choices within the set of interchangeables. In organizational life, media choice transpires sequentially, with each choice conditioning a succeeding one. In its dynamic form, the present model explicitly incorporates such sequential environments: The twofold choice process transpires iteratively within individual decision sites (in the multiple purchasing decisions of a committee, for example) and sequentially across decision sites (from committee to individual, for example). The model generates considerable empirical implications. As decisional ambiguity grows, the rational-choice component of the choice process shrinks, implying upper-bound conditions for the explanatory power of rational-choice statistical models.  相似文献   
7.
Trusting Virtual Trust   总被引:2,自引:0,他引:2  
Can trust evolve on the Internet between virtual strangers? Recently, Pettit answered this question in the negative. Focusing on trust in the sense of ‘dynamic, interactive, and trusting’ reliance on other people, he distinguishes between two forms of trust: primary trust rests on the belief that the other is trustworthy, while the more subtle secondary kind of trust is premised on the belief that the other cherishes one’s esteem, and will, therefore, reply to an act of trust in kind (‘trust-responsiveness’). Based on this theory Pettit argues that trust between virtual strangers is impossible: they lack all evidence about one another, which prevents the imputation of trustworthiness and renders the reliance on trust-responsiveness ridiculous. I argue that this argument is flawed, both empirically and theoretically. In several virtual communities amazing acts of trust between pure virtuals have been observed. I propose that these can be explained as follows. On the one hand, social cues, reputation, reliance on third parties, and participation in (quasi-) institutions allow imputing trustworthiness to varying degrees. On the other, precisely trust-responsiveness is also relied upon, as a necessary supplement to primary trust. In virtual markets, esteem as a fair trader is coveted while it contributes to building up one’s reputation. In task groups, a hyperactive style of action may be adopted which amounts to assuming (not: inferring) trust. Trustors expect that their virtual co-workers will reply in kind while such an approach is to be considered the most appropriate in cyberspace. In non-task groups, finally, members often display intimacies while they are confident someone else ‘out there’ will return them. This is facilitated by the one-to-many, asynchronous mode of communication within mailing lists.  相似文献   
8.
代位执行,是基于民法中债权人代位权的原理而形成的一种执行法律制度.研究目前代位执行程序和实体上存在的诸如代位执行程序中第三人异议的处理问题,代位执行中到期债权的范围延伸问题等有助于代位执行权更好地行使.  相似文献   
9.
As technology becomes more accessible and acceptable in the preschool setting, teachers need effective strategies of incorporating it to address challenging behaviors. A nonconcurrent delayed multiple baseline design in combination with an alternating treatment design was utilized to investigate the effects of using iPad tablets to display video self‐modeling and activity photos for three preschoolers during circle time. During baseline, all three children demonstrated low levels of engagement and high levels of off‐task behavior compared to peers. The intervention phase consisted of alternating between showing the child the self‐video and photos prior to circle time. A child preference phase was conducted whereby each child self‐selected the video or photo prior to circle time. For all three children both videos and photos led to increased engagement and decreased off‐task behaviors. During the child preference phase, all three children selected the video most frequently. Social validity data demonstrated teacher and child preference for the video self‐modeling condition.  相似文献   
10.
An expansion theory of spherical cavities in strain-softening materials with different moduli of tension and com-pression was presented. For geomaterials,two controlling parameters were introduced to take into account the different moduli and strain-softening properties. By means of elastic theory with different moduli and stress-softening models,general solutions cal-culating Tresca and Mohr-Coulomb materials' stress and displacement fields of expansion of spherical cavity were derived. The effects caused by different elastic moduli in tensile and compression and strain-softening rates on stress and displacement fields and development of plastic zone of expansion of cavity were analyzed. The results show that the ultimate expansion pressure,stress and displacement fields and development of plastic zone vary with the different elastic moduli and strain-softening prop-erties. If classical elastic theory is adopted and strain-softening properties are neglected,rather large errors may be the result.  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