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211.
深空探测活动离不开深空测控网的支持,但是,现有航天测控系统不能满足深空探测工程的需求。VLBI测量技术测量精度高,定轨时间短,是一种很好的深空测量方法。文章讨论了VLBI的概念和差分VLBI的基本原理,VLBI的定位体制及角度测量的变换,详细分析了差分VLBI的测量精度,并展望了ΔVLBI在我国未来深空探测中的应用前景。 相似文献
212.
本文以安徽科技学院图书馆公共空间环境为研究对象,借助心理实验的SD法,从人的感知情况进行评价,并对收集到的实验数据进行归纳分析,得出更为全面的空间环境评价结果。从而为图书馆内部公共空间环境的舒适性提出相应改进措施,并在此研究方向上探索一种可行的技术手段和提供有利的参考价值。 相似文献
213.
文章主要利用了Banach空间中Krasnoselskii锥不动点定理理论,研究了一类中立型泛函微分方程ddt(x(t)-c(t)x(t-τ(t)))=-a(t)x(t)+g(t,x(t-τ(t)))+p(t)周期解的存在性,得出了周期解存在的充分条件。 相似文献
214.
“微分方程的通解”探析 总被引：1，自引：0，他引：1
吴全荣 《漯河职业技术学院学报》2009,8(2):130-132
剖析了“微分方程的通解”的定义,并商榷了一些教科书（教参）中解微分方程的方法,分析解微分方程时常出现的一些错误：失根;随意去掉绝对值的符号、随意将三角函数改写成反三角函数或把反三角函数改写成三角函数形式而改变函数定义域。 相似文献
215.
This study examined the effects of classroom indegree for ability (the degree to which peer nominations as academically capable show high consensus and focus on a relatively few number of children in a classroom) on first grade children's peer acceptance, teacher-rated classroom engagement, and self-perceived cognitive competence. Participants were 291 children located in 84 classrooms. Participating in sociometric interviews were 937 classmates. Consistent with social comparison theory, classroom indegree moderated the associations between children's achievement and classroom engagement and peer liking. Children with lower ability, relative to their classmates, were less accepted by peers and less engaged in classrooms in which students' perceptions of classmates' abilities converged on a relatively few number of students than in classrooms in which peers' perceptions were more dispersed. High indegree was associated with lower self-perceived cognitive competence regardless of ability level. 相似文献
216.
Bernardita Muñoz-Chereau 《School Effectiveness & School Improvement》2013,24(2):83-103
ABSTRACTDespite the systematic recognition of large gender gaps in favour of boys in mathematics performance in Chile, the role of schools in explaining this gap has been comparatively underresearched. This paper analyses a longitudinal dataset to explore within- and between-school variation of Chilean primary schools in promoting attainment and progress of girls and boys. In order to reflect the hierarchical nature of the educational data, multilevel modelling is used, with 163,044 students, nested within 3,355 schools, within 310 municipalities to fit raw, contextualised attainment, and value-added models. The weak evidence indicative of gender differential school effect in progress in Chilean primary schools was interpreted as non-substantive. However, differences in effectiveness played a significant role, as girls progressed more than boys in less effective schools, but the opposite was true in more effective schools. Finally, the study concludes that the Chilean gender gap needs to be addressed mainly beyond schools. 相似文献
217.
利用循环伏安法(CV)和模板(阳极氧化铝模板(AAO),制备出多孔粗糙金纳米管,壳聚糖将(AAO制备所得)其固定在玻碳电极上,然后将模板溶解,制得金纳米管修饰的传感器,并将其用于抗坏血酸(AA)和尿酸(UA)的直接电化学测定。利用电子扫描电镜(SEM)分析了金纳米管的微观形貌,通过微分差示脉冲伏安(DPV)和循环伏安法考察了抗坏血酸和尿酸在修饰电极上的电化学行为。结果表明,该传感器检测抗坏血酸和尿酸的线性范围分别为1.02×10-7～5.23×10-4mol·L-1和1.43×10-7～4.64×10-4mol·L-1,检测下限分别为1.12×10-8mol·L-1和2.24×10-8mol·L-1。该传感器具有稳定性好,制作简单,使用寿命长等特点,为实际样品中抗坏血酸和尿酸的测定提供了一种新的简便手段。 相似文献
218.
In this study, we examined whether high-school students experienced optimal educational and well-being outcomes when they perceived that they and their classmates received an equal, rather than unequal, and high amount of autonomy support from teachers. In a prospective study that aimed to predict academic grades and well-being outcomes, surface analyses of polynomial regression equations pointed that perceptions of equal autonomy support were the most optimal in terms of yielding highest levels of need satisfaction, autonomous forms of motivation and happiness with math courses. Additionally, in accordance with tenets of self-determination theory, we demonstrated that effects associated with perceptions of equal autonomy support were mediated by autonomous forms of motivation and psychological needs. Findings suggest that researchers and practitioners may be able to facilitate optimal educational and well-being outcomes by encouraging teachers to distribute autonomy support equally across students. 相似文献
219.
220.
杨玉敏 《鞍山师范学院学报》2010,12(6):5-9
微分中值定理是微积分学基本定理之一,是研究函数性态的有利工具.本文首先给出了微分中值定理及其推广形式,并对中值定理中点的位置、拉格朗日中值定理、柯西中值定理和积分中值定理的关系进行了探讨. 相似文献