全文获取类型
收费全文 | 2795篇 |
免费 | 29篇 |
国内免费 | 71篇 |
专业分类
教育 | 2255篇 |
科学研究 | 346篇 |
各国文化 | 1篇 |
体育 | 39篇 |
综合类 | 150篇 |
文化理论 | 1篇 |
信息传播 | 103篇 |
出版年
2023年 | 3篇 |
2022年 | 17篇 |
2021年 | 28篇 |
2020年 | 45篇 |
2019年 | 47篇 |
2018年 | 22篇 |
2017年 | 31篇 |
2016年 | 25篇 |
2015年 | 60篇 |
2014年 | 162篇 |
2013年 | 152篇 |
2012年 | 169篇 |
2011年 | 222篇 |
2010年 | 157篇 |
2009年 | 172篇 |
2008年 | 202篇 |
2007年 | 216篇 |
2006年 | 205篇 |
2005年 | 161篇 |
2004年 | 155篇 |
2003年 | 135篇 |
2002年 | 110篇 |
2001年 | 88篇 |
2000年 | 64篇 |
1999年 | 50篇 |
1998年 | 39篇 |
1997年 | 38篇 |
1996年 | 28篇 |
1995年 | 14篇 |
1994年 | 18篇 |
1993年 | 8篇 |
1992年 | 20篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1981年 | 1篇 |
排序方式: 共有2895条查询结果,搜索用时 31 毫秒
31.
任秋道 《绵阳师范学院学报》2007,26(11):14-17
图G的特征值是图的一个重要不变量。在量子化学和理论化学中有大量的应用。当图G的顶点数较大时,其邻接矩阵的阶数较大,计算特征值较困难。分块降阶是通常的方法。本文针对一些特殊图的邻接矩阵进行分块降阶求特征值。如果在V(G)上有一个一一映射φ,使得φ(vi)=vn-i 1,i=1,2,…,n,那么G的点v1仅与G的点v1重合的图G G的特征值中有G-V1的特征值。 相似文献
32.
INTRODUCTION A common method for extracting depth in-formation from intensity images is based on theprinciples of stereovision. In this method, a pair ofimages is obtained using two cameras displacedfrom each other by a known distance. After deter-mining the stereo correspondence, the distance ofvarious points is computed using triangulation(Jeon et al., 2001). Stereo correspondence is theproblem of finding corresponding points in two ormore images of the same scene, usually assumin… 相似文献
34.
35.
给出了有单位元的C*-代数上可逆矩阵的特征,讨论了C*-代数上部分矩阵的可逆补问题,得到C*-代数上部分矩阵(a? cb)有可逆补的条件. 相似文献
36.
This paper explores the Estonian novice teachers’ learning and knowledge building (LKB) practices in the extended professional community during the induction programme using well-known knowledge conversion model. The assumption in this study is that a teachers’ participation in the extended professional community facilitates their professional development. The survey was conducted with 101 novices after their induction programme. The patterns of novices’ LKB practices in the professional learning community during the induction programme were explored. The analysis showed to what extent extended professional community may be formed during the induction year. LKB practice patterns among the novices were identified. We discovered that many novices felt that there was insufficient support from other teachers and from university experts. It appears that it is challenging to develop a coherent induction programme as the extended professional community of educators, where different partners collaborate and share professional knowledge is challenging. 相似文献
37.
经济哲学与宏观经济调控方略在经济发展中的重要性显而易见.回顾经济学流派的各种经济政策展示了调控的显著性,在当今国际经济一体化过程中,宏观经济政策的贫乏越加显现出来.创新是首要任务.以宏观经济指标理论,政策性和阶段性的宏观调控策略.宏观经济良性循环三大任务为综合目标的七元素调控宏观经济的数学模型是三率调控宏观经济的进一步深入和细致,我们分析了税收,存款利率,贷款利率,汇率,货币发行量,国债发行量,财政预算七元素与30个宏观经济指标变量间的经验关系,并由此建立粗略的阶段性的效益矩阵作为决策的基础.利用宏观经济指标对经济的贡献率确定加权系数,并建立线性的目标函数并求出离散组合优化值,为中国宏观经济的发展献一点调控策略。供政府部门的决策者参考. 相似文献
38.
39.
基于分子结构矩阵的醇类化合物色谱保留指数的预测 总被引:1,自引:1,他引:0
根据分子结构创建了分子结构矩阵,将分子结构矩阵的行数、列数以及其向量的一范数的算术平方根为分子的结构信息指数,并将多元统计学中的因子分析方法引入QSPR/QSAR研究中,以优化的变量因子为自变量,预测了25种醇类化合物的色谱保留指数,结果令人满意. 相似文献
40.
Kevin H. Ashford-Rowe Marnie Holt 《美中教育评论》2011,(3):317-322
The "emerging educational institutional decision-making matrix" is developed to allow educational institutions to adopt a rigorous and consistent methodology of determining which of the myriad of emerging educational technologies will be the most compelling for the institution, particularly ensuring that it is the educational or pedagogical but not the technological imperative that drives the technology integration agenda. The matrix is designed to be used after some initial research into an emerging technology. Once a technology is put through the matrix, a member of options are available: (1) shelving the technology; (2) putting the technology on hold and maintaining a watching brief until the technology matures in the market; and (3) researching the product further by conducting a trial or placing in testing sandpit. After further research, the technology can be tested as a pilot to determine how well or otherwise, the technology works within the institution. If an emerging technology has more than one product associated with it, a second and third step in the matrix has been developed, and the second step assigns a rating to each of the categories within the matrix. With many products containing similar features, a third step has been developed to compare products on a feature level. 相似文献