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排序方式: 共有937条查询结果,搜索用时 15 毫秒
141.
研究了一类具有偏差变元的高阶中立型微分方程周期解问题.利用重合度理论,获得了其周期解的存在性和唯一性的充分条件. 相似文献
142.
Nowadays, almost all curricula in the social sciences contain at least one course in statistics, given the importance of this discipline as an analytical tool. This work identifies the latent factors relating to students' motivation and attitude towards statistics, tests their covariance structure for samples of both sexes, and identifies the possible differences between the sexes. Specifically, using a structural equations model the work confirms that the evaluative factors affect the affective factors and the interest variable affects the level of anxiety. The findings obtained using the partial least squares method allow the authors to confirm the proposed relations and validate the model. 相似文献
143.
144.
张立军 《深圳职业技术学院学报》2009,8(2):3-8
证券市场是宏观经济的“晴雨表”,股票市场与宏观经济的关系一直是研究的热点问题。本文通过分析我国证券市场的发展情况,以及股价指数与主要经济变量之间的关系,建立了宏观经济变量与证券市场波动的联立方程模型,并利用1992年1月到2007年12月的月度数据进行了实证分析。 相似文献
145.
在已有文献所给的解一元四次方程方法的基础上,给出了求解四阶常系数方程的详细步骤,同时,利用常数变易法和分部积分法,以及高等代数的相关知识,得到了在两种情况下四阶常系数非齐次线性微分方程特解的两个定理. 相似文献
146.
通过惩罚估计方程,对响应变量随机缺失下的线性回归模型,给出了一个变量选择方法,并结合局部二次逼近,得到了一个迭代算法,证明了此变量选择方法是相合的并且所得估计达到最优的参数收敛速度,最后通过数据模拟研究了此方法的有限样本性质. 相似文献
147.
鄢盛勇 《四川教育学院学报》2009,25(1):111-114
用函数论的方法研究了一类线性超定双曲型方程组的解,即多双曲复数的一类广义双曲正则函数,在一般柱形域上它的Riemann-Hilbert边值问题的提法,可解条件,解的表示,唯一性和存在性。 相似文献
148.
Andrew M Lane Chris Harwood Peter C Terry Costas I Karageorghis 《Journal of sports sciences》2013,31(9):803-812
The aim of the present study was to examine the factorial validity of the Test of Performance Strategies (TOPS; Thomas et al., ) among adolescent athletes using confirmatory factor analysis. The TOPS was designed to assess eight psychological strategies used in competition (i.e. activation, automaticity, emotional control, goal-setting, imagery, negative thinking, relaxation and self-talk,) and eight used in practice (the same strategies except negative thinking is replaced by attentional control). National-level athletes (n?=?584) completed the 64-item TOPS during training camps. Fit indices provided partial support for the overall measurement model for the competition items (robust comparative fit index?=?0.92, Tucker-Lewis index?=?0.88, root mean square error of approximation?=?0.05) but minimal support for the training items (robust comparative fit index?=?0.86, Tucker-Lewis index?=?0.81, root mean square error of approximation?=?0.06). For the competition items, the automaticity, goal-setting, relaxation and self-talk scales showed good fit, whereas the activation, emotional control, imagery and negative thinking scales did not. For the practice items, the attentional control, emotional control, goal-setting, imagery and self-talk scales showed good fit, whereas the activation, automaticity and relaxation scales did not. Overall, it appears that the factorial validity of the TOPS for use with adolescents is questionable at present and further development is required. 相似文献
149.
Amador García-Ramos Paola Barboza-González David Ulloa-Díaz Angela Rodriguez-Perea Darío Martinez-Garcia Francisco Guede-Rojas 《Journal of sports sciences》2013,31(19):2205-2212
ABSTRACTThis study examined the reliability and validity of three methods of estimating the one-repetition maximum (1RM) during the free-weight prone bench pull exercise. Twenty-six men (22 rowers and four weightlifters) performed an incremental loading test until reaching their 1RM, followed by a set of repetitions-to-failure. Eighteen participants were re-tested to conduct the reliability analysis. The 1RM was estimated through the lifts-to-failure equations proposed by Lombardi and O’Connor, general load-velocity (L-V) relationships proposed by Sánchez-Medina and Loturco and the individual L-V relationships modelled using four (multiple-point method) or only two loads (two-point method). The direct method provided the highest reliability (coefficient of variation [CV] = 2.45% and intraclass correlation coefficient [ICC] = 0.97), followed by the Lombardi’s equation (CV = 3.44% and ICC = 0.94), and no meaningful differences were observed between the remaining methods (CV range = 4.95–6.89% and ICC range = 0.81–0.91). The lifts-to-failure equations overestimated the 1RM (3.43–4.08%), the general L-V relationship proposed by Sánchez-Medina underestimated the 1RM (?3.77%), and no significant differences were observed for the remaining prediction methods (?0.40–0.86%). The individual L-V relationship could be recommended as the most accurate method for predicting the 1RM during the free-weight prone bench pull exercise. 相似文献
150.