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谭维奇 《南京广播电视大学学报》1998,(1)
根据题设条件把所求解的问题转化为对一函数性质的讨论,从而使所求解的问题得到答案,称为构造函数解题。通过构造函数,利用函数的单调性解题,在解方程和证明不等式中的应用最为广泛,解题思路简捷明快。下面举例说明。 一、解方程 相似文献
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周学勤 《濮阳职业技术学院学报》2008,21(3)
微分中值定理和泰勒公式是微分学的基本公式,是构成微分学基础理论的重要内容。微分中值定理是利用函数导数所具有的性质去研究函数本身在区间上的性质的一个非常有利的工具,它包括Rolle中值定理、Lagrange中值定理、Cauchy中值定理。泰勒中值公式在证明和求解等方面有着广泛的应用。本文通过举例说明二者在解题中的广泛应用。 相似文献
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关于定积分第一中值定理的证法，目前的数学分析教材和参考书都是利用四区间连续函数的性质──—最值性定理和介值性定理，以及定积分的单调性和线性性来进行证明的。本文将力图采用一种新的方法对定积分第一中值定理加以证明，即借助积分上限函数，利用微分学中值定理来证明。1第一积分中值定理1若函数f（C）在闭区间已、hi连续，则在O、匆上至少存在一点C，使证明：已知函数人x）在闭区间［a·幻的连续，根据积分上限函数的性质定理，积分上限函数在k，匆上可异，且严（X）一八）。显然，函数F（x）ZIf（）dt在（a，b）上满足拉格明日… 相似文献
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新闻标题在新闻信息的传播过程中起着重要作用。预设在新闻标题的编辑中有着广泛地应用。语料分析表明,预设机制的策略性使用在新闻标题中至少可以发挥五种语用功能:预设具有过程关联的功能;预设具有过程选择的功能;预设具有语境动态过程的功能;预设具有在语言成分和语境间动态互顺的功能;预设具有元语用意识功能。从语用角度考察新闻标题中的预设现象,不仅可以补充语用预设研究的理论解释力,而且可以增加新闻标题的编辑效果以及对新闻内容的预测力。这些功能通过不同类型的预设机制来实现。 相似文献
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Emma Blakey Danielle Matthews Lucy Cragg Jessica Buck David Cameron Ben Higgins Lisa Pepper Ellen Ridley Emma Sullivan Daniel J. Carroll 《Child development》2020,91(5):1594-1614
The socioeconomic attainment gap in mathematics starts early and increases over time. This study aimed to examine why this gap exists. Four-year-olds from diverse backgrounds were randomly allocated to a brief intervention designed to improve executive functions (N = 87) or to an active control group (N = 88). The study was preregistered and followed CONSORT guidelines. Executive functions and mathematical skills were measured at baseline, 1 week, 3 months, 6 months, and 1 year posttraining. Executive functions mediated the relation between socioeconomic status and mathematical skills. Children improved over training, but this did not transfer to untrained executive functions or mathematics. Executive functions may explain socioeconomic attainment gaps, but cognitive training directly targeting executive functions is not an effective way to narrow this gap. 相似文献
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严敏芬 《徐州师范大学学报(哲学社会科学版)》2000,26(2):56-59
从英语小句形式与功能间的相互关系出发,对英语小句言语功能变异出现范围、方式以及特点进行探讨,可以得出以下结论1．小句言语功能变异是由小句元言语功能丧失．导致语句形式与功能不对应而产生;2．小句言语功能变异还应包括言语功能类型的重舍和毗邻语对中言语功能脱链两种形式;3．小句言语功能变异还有层次性与网络性等突出特点。 相似文献
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The aim of this study was to identify the specific contribution of executive functions to pre-academic skills (emergent literacy, phonological awareness and orthographic knowledge, and emergent mathematic knowledge) over and above cognitive and linguistic underpinning abilities such as naming, short-term memory and vocabulary. The study was designed to examine the following questions: (1) Are executive functions related to pre-academics skills in general or are they related to specific pre-academic skills? (2) Does the magnitude of the relationship between executive functions and pre-academics skills change with the progress in pre-school age? 54 children between the ages of 5 and 6 years old from 4 different kindergartens participated in the project. A wide range of pre-academic skills, cognitive, linguistic and executive functions tasks were administered. The results demonstrated that executive functions contributed significantly to both emergent literacy and emergent mathematic knowledge. In addition, the current study also suggests that the role of executive functions increases with the growth of child’s pre-academic development. Finally, the strongest contribution of executive functions was found to orthographic knowledge. 相似文献
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The present study examined the patterns of perceived management functions of deans and department chairpersons in three schools: social sciences, physical sciences and medical school. In all schools, deans were perceived as paying utmost attention to outside activities, and least attention to inside activities. The study explored the relationships between personal career data and scales of perceived managerial functions on one hand, and between job satisfaction and management functions on the other hand. Articles were found to be negatively correlated with perceptions of managerial functions in all schools. Seniority, rank, and tenure were positively associated with inside activities of the dean and the chairperson in the social sciences. Managerial functions were positively related especially to satisfaction with governance. The implications of the results were discussed and elaborated. 相似文献
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In this paper, the Tφ-convex functions were introduced as a generalizations of convex functions. Then the characteristics of the Tφ-convex functions were discussed. Furthermore, some new inequalities for the Tφ-convex functions were derived. 相似文献
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岳阳方言的形容词重叠形式丰富,构成复杂,颇具方言特点。文章主要探讨岳阳方言形容词重叠式的构形特征和句法功能,并对该重叠式的基式“AB”和“BA”式形容词进行重点探究。认为“A”和“B”结合时,“AB”和“BA”基式的构型、意义及句法功能都有差异,通过重叠构成的形容词重叠式,其构形及句法功能也各有特点。 相似文献