全文获取类型
收费全文 | 5094篇 |
免费 | 85篇 |
国内免费 | 127篇 |
专业分类
教育 | 4319篇 |
科学研究 | 557篇 |
各国文化 | 10篇 |
体育 | 87篇 |
综合类 | 264篇 |
信息传播 | 69篇 |
出版年
2024年 | 1篇 |
2023年 | 15篇 |
2022年 | 34篇 |
2021年 | 53篇 |
2020年 | 69篇 |
2019年 | 79篇 |
2018年 | 75篇 |
2017年 | 70篇 |
2016年 | 70篇 |
2015年 | 89篇 |
2014年 | 238篇 |
2013年 | 328篇 |
2012年 | 332篇 |
2011年 | 361篇 |
2010年 | 273篇 |
2009年 | 300篇 |
2008年 | 280篇 |
2007年 | 397篇 |
2006年 | 332篇 |
2005年 | 281篇 |
2004年 | 241篇 |
2003年 | 280篇 |
2002年 | 207篇 |
2001年 | 209篇 |
2000年 | 146篇 |
1999年 | 119篇 |
1998年 | 68篇 |
1997年 | 89篇 |
1996年 | 75篇 |
1995年 | 40篇 |
1994年 | 43篇 |
1993年 | 22篇 |
1992年 | 27篇 |
1991年 | 15篇 |
1990年 | 18篇 |
1989年 | 14篇 |
1988年 | 12篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1977年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有5306条查询结果,搜索用时 15 毫秒
21.
Abstract Within education, some teachers’ interpretation of professionalism emphasizes conformity to the perceived norms of collective associations. Unprofessional behaviour, often equated with ‘unethical’ behaviour, is seen by many to be that which threatens solidarity and loyalty to colleagues. Informal norms typified by casual collegial relations as well as more formal attachments to organized unions or teachers’ federations exert a significant influence on individuals’ behaviour within the group. Professional ethics, in this sense, become concerned primarily with how one relates to colleagues rather than how one fulfils moral responsibilities to students. Qualitative findings from interviews with elementary and secondary school teachers suggest that, as a result of an ethic of collegial loyalty, some teachers experience personal moral and ethical dilemmas that they find difficult to resolve. Some respondents acknowledged that this can enable serious situations to be ignored or ‘covered up’. This paper examines some of the tensions and dilemmas experienced by teachers and raises questions about the ethical adequacy of defining professionalism in terms of inter‐colleague behaviour. 相似文献
22.
统计过程控制是过程监控与故障诊断的方法。在多变量统计过程控制中,传统的方法主要包括主元分析和偏最小二乘,这些方法存在着诸多缺陷。设计时可以应用非线性主元分析、非线性偏最小二乘、动态主元分析、自适应主元分析、多尺度主元分析等方法进行改进。研究中要重视带噪声的监控模型、过程模型信息与经验知识相结合等问题,同时可以把一些新的降维技术用于统计过程控制中。 相似文献
23.
宿娟 《四川教育学院学报》2013,(11):116-118
函数极值的存在性及判别方法是微分的重要应用之一.文章就三元函数给出了判别极值的存在的一个必要条件和充分条件. 相似文献
24.
Central to equation solving is the maintenance of equivalence on both sides of the equation. However, when the process involves an interaction of multiple elements, solving an equation can impose a high cognitive load. The balance method requires operations on both sides of the equation, whereas the inverse method involves operations on one side only. In an experiment, middle school students (N?=?71) were randomly assigned to the balance and inverse methods to complete a pre-test, an acquisition phase and a post-test. Pre-test and post-test comparisons found that the inverse group outperformed the balance group for those equations that involved high element interactivity. Instructional efficiency measures further confirmed that the balance method imposed higher cognitive load. The inverse method was capable of reducing cognitive load due to the interacting elements. 相似文献
25.
本文采用基于KdV方程的守恒量建立起来的孤波参数的演化方程组,重新研究了粘弹性阻尼对非线性弹性杆内纵向应变孤波运动的影响,得到了孤波参数的演化规律。结果表明,粘弹性阻尼使孤波逐渐变矮、增宽、速度减慢,最后导致孤波的消失。 相似文献
26.
27.
连分数的展开式具有结构上的自相似性,部分商满足一定条件的连分数构成的集合是分形集,通过构造迭代映射的方法估算其Hausdorff维数. 相似文献
28.
Expectancy-value researchers have theorized about the extent to which subjective task value components are more trait-like or more state-like. Using a bifactor representation of subjective task value data, the current study aimed to examine the degree of trait-state variation in general subjective task value, specific attainment value, specific intrinsic value, and specific utility value. The relations of both between and within components of the subjective task value constructs with academic self-efficacy beliefs were also examined. Results indicate that, in an undergraduate life science learning context (n = 169), the general subjective task value factor was the most trait-like of the subjective task value constructs. With respect to specific value beliefs, attainment value was composed of nearly equal amounts of trait and state variation, intrinsic value was composed of the largest amount of trait variation, and utility value exhibited the most state-like variation. Additionally, findings suggest that trait-like and state-like general subjective task value, trait-like specific intrinsic value, and state-like attainment value were positively associated with self-efficacy. Finally, we propose a model of trait- state dynamics in subjective task value. 相似文献
29.
胡宇峰 《衡阳师范学院学报》2014,(3):11-13
研究一类广义Liénard方程周期解的不存在性,给出了其周期解不存在的两个充分条件,用极限集理论与Poincaré切性曲线法证明了所得结果。 相似文献
30.
基于新鲜度和配送成本的易腐食品配送路径 总被引:1,自引:0,他引:1
为解决企业在制定易腐食品配送计划时难以权衡配送总成本与交付产品的新鲜度的问题,建立以配送总成本最低和交付产品平均新鲜度最大为目标,带时间窗的易腐食品配送路径规划模型。采用自适应差分进化(differential evolution,DE)算法求解模型,通过数值算例验证模型和算法的有效性。与基本DE算法和基本蚁群算法的求解结果进行对比,自适应DE算法的求解结果更优,收敛速度更快。求得的帕累托解集表明配送总成本与交付产品平均新鲜度相悖,增加少量的配送成本可以使交付产品的平均新鲜度得到大幅提升。对易腐食品保质期、时间窗宽度和车辆装载量进行灵敏度分析,为企业在不同配送情景下在配送总成本与交付产品的平均新鲜度之间的权衡提供参考。 相似文献