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   681篇
  免费   49篇
  国内免费   15篇
财政金融   44篇
工业经济   44篇
计划管理   252篇
经济学   92篇
综合类   85篇
运输经济   9篇
旅游经济   9篇
贸易经济   104篇
农业经济   55篇
经济概况   51篇
  2024年   2篇
  2023年   7篇
  2022年   7篇
  2021年   17篇
  2020年   26篇
  2019年   19篇
  2018年   24篇
  2017年   24篇
  2016年   9篇
  2015年   30篇
  2014年   54篇
  2013年   67篇
  2012年   58篇
  2011年   49篇
  2010年   41篇
  2009年   43篇
  2008年   32篇
  2007年   50篇
  2006年   49篇
  2005年   25篇
  2004年   23篇
  2003年   18篇
  2002年   14篇
  2001年   12篇
  2000年   8篇
  1999年   6篇
  1998年   5篇
  1997年   3篇
  1996年   1篇
  1995年   5篇
  1994年   6篇
  1991年   3篇
  1990年   1篇
  1989年   4篇
  1987年   1篇
  1984年   1篇
  1982年   1篇
排序方式: 共有745条查询结果,搜索用时 46 毫秒
1.
The American Psychological Association Task Force recommended that researchers always report and interpret effect sizes for quantitative data. However, no such recommendation was made for qualitative data. Thus, the first objective of the present paper is to provide a rationale for reporting and interpreting effect sizes in qualitative research. Arguments are presented that effect sizes enhance the process of verstehen/hermeneutics advocated by interpretive researchers. The second objective of this paper is to provide a typology of effect sizes in qualitative research. Examples are given illustrating various applications of effect sizes. For instance, when conducting typological analyses, qualitative analysts only identify emergent themes; yet, these themes can be quantitized to ascertain the hierarchical structure of emergent themes. The final objective is to illustrate how inferential statistics can be utilized in qualitative data analyses. This can be accomplished by treating words arising from individuals, or observations emerging from a particular setting, as sample units of data that represent the total number of words/observations existing from that sample member/context. Heuristic examples are provided to demonstrate how inferential statistics can be used to provide more complex levels of verstehen than is presently undertaken in qualitative research.  相似文献   
2.
各向异性厚板固有频率的精确解   总被引:3,自引:0,他引:3  
该文抛弃薄板理论的位移和应力假设,利用矩阵分析和三维弹性动力学理论,导出四边简支各向异性厚板的固有频率方程。该方法可推广应用于各向异性层合板动力分析。  相似文献   
3.
The economic impact of adopting herd health programs for mastitis and reproduction by small-scale dairy producers of Central Thailand was assessed using a policy analysis matrix (PAM). Following a reduction in the incidence of bovine disease on adopter farms, an increase in private net profits is observed. More importantly the social costs of supporting dairy farmers is reduced; the PAM effective protection coefficient was reduced by 35% for mastitis program adopters and by 44% for reproductive program adopters, indicating improved social efficiency of dairy policy. Other indicators of efficiency and policy implications are discussed.  相似文献   
4.
For an arbitrary subset A of the finite state space 5 of a Markov chain the so–called embedded matrix P A is introduced. By use of these matrices formulas expressing all kinds of probabilities can be written down almost automatically, and calculated very easily on a computer. Also derivations can be given very systematically.  相似文献   
5.
Progressive stress accelerated life tests under finite mixture models   总被引:1,自引:0,他引:1  
In this paper, progressive stress accelerated life tests are considered when the lifetime of a product under use condition follows a finite mixture of distributions. The experiment is performed when each of the components in the mixture follows a general class of distributions which includes, among others, the Weibull, compound Weibull, power function, Gompertz and compound Gompertz distributions. It is assumed that the scale parameter of each component satisfies the inverse power low, the progressive stress is directly proportional to time and the cumulative exposure model for the effect of changing stress holds. Based on type-I censoring, the maximum likelihood estimates (MLEs) of the parameters under consideration are obtained. A special attention is paid to a mixture of two Rayleigh components. Simulation results are carried out to study the precision of the MLEs and to obtain confidence intervals for the parameters involved.  相似文献   
6.
基于风险矩阵的物流外包风险评估   总被引:4,自引:0,他引:4  
分析了物流外包中存在的风险,将风险矩阵引入到物流外包的风险评估中,为物流外包提供了一种结构性风险评估方法。并以某生产企业配送外包为例对风险矩阵的应用进行了说明。  相似文献   
7.
In this paper, we consider the problem of estimating a selected set of contrasts between v treatments using a block design consisting of b blocks of size k. Traditionally, the construction of A-optimal block designs for such situations has been carried out assuming a fixed effects model. In this paper, we show that A-optimal designs constructed under a fixed effects model are robust in the sense that these designs have maximal minimal efficiency when considered among all available designs and under all possible mixed effects models. AMS 1991 subject classifications: Primary 62K05; Secondary 62K10  相似文献   
8.
Comprehensive transportation evaluation objects using multi-objective decision method is a process of choosing the best one from a few objects through calculating, analyzing, and comparing the index system. The result may be different because of the difference of the index weight and index value. Therefore, sensitivity analysis should be one of the necessary parts of the decision-making. It is desired to give the index with higher sensitivity and its varying scope to control the index strictly during the execution process. This paper derives transfer index weight, which changes the rank evaluation order of the projects. Meanwhile, a simple, effective and practical method based on sensitivity district and sensitivity matrix is proposed for the sensitivity analysis of decision-making. As an example, the index sensitivity in decision-making of some provinces comprehensive transportation objects, and their influence on the final decision are discussed.  相似文献   
9.
王梯 《物流科技》2006,29(12):128-130
ITS研究中,动态OD矩阵估计是交通动态分配的关键因素。针对OD矩阵难以获得的问题,回顾动态OD矩阵估计理论的发展历程,明确该领域研究中的三个关键问题:状态变量的选择、系统方程的确定、OD量与路段流量的关系(分配矩阵)。在此基础上介绍一种基于历史OD矩阵数据的估计方法,卡尔曼滤波算法,为动态OD矩阵估计理论的进一步的研究奠定基础。  相似文献   
10.
Jainz  M. 《Metrika》2003,58(3):273-277
We show that the projections on four factors of an arbitrary orthogonal array of strength 2 allow the estimation of main effects and two-factor interactions when all other effects are assumed to be zero, if those projections satisfy the bounds given by Weils theorem. The only exceptions are the Hadamard matrices of orders 16 and 24. A consequence is again the estimability of main effects and two-factor interactions for the projections on four factors of the first Payley construction for arbitrary run size.  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