求解多元函数极值的一种新方法     

李文宇 《鸡西大学学报》2006,6(2):91-92

本文给出了三元函数极值的充分条件和必要条件,并把它推广到了多元函数,给出了求多元函数极值的一个新方法。  相似文献   

关于Pro/E环境变量设置的探讨     

刘立新  任海东 《张家口职业技术学院学报》2011,24(2):60-63

在运用Pro/E设计软件将三维模型转换为工程图时,正确设置系统环境变量和工程图环境变量,可以快速绘制出符合我国国家标准的工程图。运用举例方法探讨Pro/E中由三维模型转化工程图时有关变量的具体设置,并使设置的变量在启动Pro/E的同时生效,从而提高绘制工程图的效率。  相似文献   

例谈数学期望在生活中的应用     

刘小红 《南昌教育学院学报》2011,26(5):60+66-60,66

数学期望是随机变量的重要数字特征之一,文章解析了数学期望在日常生活中的应用,如求职决策问题,投资问题,彩票问题等,从而不断激发学生学习数学的积极性和主动性,让学生在兴趣中学习探索,并应用于生活,让数学改变生活。  相似文献   

Theoretical and methodological implications of associations between executive function and mathematics in early childhood     

《Contemporary educational psychology》2019

Despite agreement about the importance of executive function (EF) for children’s early math achievement, its treatment in correlational studies reflects a lack of agreement about the theoretical connection between the two. It remains unclear whether the association between EF and math operates through a latent EF construct or specific EF components. Specifying the correct measurement model has important theoretical implications for the predicted effects of EF interventions on children’s math achievement. In the current study, we tested whether associations between EF and math operate via a latent EF factor, or via specific EF components using data from a large, nationally representative sample. We then replicated these same analyses with a meta-analytic database drawn from ten studies that collected measures of children’s EF and math achievement. Our results lend support to explanations that a single EF factor accounts for most of the EF component-specific associations with math achievement. We discuss theoretical and methodological implications of these findings for future work.  相似文献   

学生个体差异:研究方法与基本结构     

曾继耘 《课程.教材.教法》2006,26(3)

对课堂教学中学生个体差异的研究主要有两种方法:一是类型化研究,二是差异变量分析。其中差异变量分析是全面动态把握学生个体差异的较好方法。从影响学生学习的主体因素角度来分析,课堂教学中学生的个体差异主要包括基础性差异、动力性差异、操作性差异和方向性差异等四个方面,它们共同构成了课堂教学中学生个体差异变量的分析框架,为我们全面检视课堂教学中学生个体差异的真实状况提供了有效的检视工具。  相似文献   

Effectiveness during ball screens in elite basketball games     

Miguel-Ángel Gómez  Otavio Battaglia  Alberto Lorenzo  Jorge Lorenzo  Sergio Jiménez  Jaime Sampaio 《Journal of sports sciences》2015,33(17):1844-1852

Ball screens are one of the most frequently used tactical behaviour in elite basketball games. The aim of the present study was to identify their predictors of success related to time, space, players, and tasks performed. The sample was composed of 818 ball screens corresponding to 20 close games (mean differences in score of 3.1 ± 0.8 points) randomly selected from the playoff games of the Spanish Basketball League (2008–2011). Classification tree analysis (CHAID) was used to analyse which variable or combination of variables, better predicts effectiveness during ball screens. The main results allowed identifying interactions with dribbler actions after the screen and the orientation of the screen on the ball. The results showed no interaction with game quarter and quarter minute temporal-related variables in both analyses. The present findings allow improving coaches’ strategic plans that involve selecting the most appropriate offensive approach when performing ball screens.  相似文献   

管理实证研究中的统计控制误用分析及改进     

张涵  康飞 《科学学与科学技术管理》2014,(10)

在管理实证研究中,统计控制误用的情况尚未得到足够重视。解释了控制变量的概念和统计控制的应用原理,并分别分析了控制变量与理论构念或测量指标相关的情况下,统计控制对分析结果的影响。通过分析表明,当控制变量与理论构念相关时,常用的统计控制方式——分层回归分析所检验的并不是自变量对因变量的总解释度,而是在考虑控制变量的情况下增加解释度;而当控制变量与测量指标相关时,分层回归分析并不适用。针对以上问题,提出了相应的统计应对策略。  相似文献   

高职生英语努力程度与动机类型变量的相关分析——以扬州职业大学师范学院为例     

潘浪  ;杨先平 《扬州教育学院学报》2014,(4):86-89

以扬州职业大学师范学院158名高职生为研究对象,分析了高职生英语学习动机类型的强度差异以及对努力程度的影响。结果表明：高职生工具性动机过于突出,而文化性动机受到明显弱化;成绩和学习情境动机变量与努力程度之间无明显相关关系,对高职生英语投入无正向促进作用;动机类型变量的强度高低与英语学习努力程度之间总是呈正比。其中出国和内在兴趣动机的作用强度最大,达到中度相关。  相似文献   

基于元分析的用户在线健康信息搜寻行为影响因素研究          下载免费PDF全文

刘嫣  张海涛  张鑫蕊  张春龙 《情报科学》2022,39(2):169-176

【目的/意义】针对现有用户在线健康信息搜寻行为的实证研究中存在的结果不一致现象,对该领域相关 研究进行梳理验证,旨在明确影响用户在线健康信息搜寻行为的真正因素以及关键调节变量,揭示用户在线健康 信息搜寻行为产生的直接原因,为完善用户在线健康信息搜寻行为理论体系及相关领域的后续研究提供借鉴。【方 法/过程】选取 25篇符合标准的中外文献进行元分析,探究影响因素及其影响程度,从国内外研究情境、用户的社 会属性与健康状况三个维度探讨影响因素与在线健康信息搜寻行为间的调节效应。【结果/结论】结果表明,10个因 素对用户在线健康信息搜寻行为有显著正向影响,其中信息质量的影响强度最高,感知风险、信任、自我效能及感 知有用性对在线健康信息搜寻行为的影响强度较弱,同时验证了国内外研究情境、用户的社会属性与健康状况对 在线健康信息搜寻行为具有调节作用。【创新/局限】本文采用元分析方法,通过对前人研究结果的再分析,得到更 加精准的研究结论,是对在线健康信息搜寻领域现有研究的有力补充。但对元分析方法的应用还较为单一,未涉 及各影响因素间的关系,有待后续进一步研究。  相似文献   

Does class-size reduction close the achievement gap? Evidence from TIMSS 2011     

Wei Li  Spyros Konstantopoulos 《School Effectiveness & School Improvement》2017,28(2):292-313

Policies about reducing class size have been implemented in the US and Europe in the past decades. Only a few studies have discussed the effects of class size at different levels of student achievement, and their findings have been mixed. We employ quantile regression analysis, coupled with instrumental variables, to examine the causal effects of class size on 4th-grade mathematics achievement at various quantiles. We use data from 14 European countries from the 2011 sample of the Trends in International Mathematics and Science Study (TIMSS). Overall, there are no systematic patterns of class-size effects across quantiles. Class-size effects are generally non-significant and uniform at different achievement levels, which suggests that in most European countries class-size reduction does not have an impact on student achievement and does not close the achievement gap. However, combined estimates across countries indicate that high achievers may benefit more from class-size reduction.  相似文献