集成运放的最小相位误差组合应用技术

针对减小集成运放相位误差的传统方法,指出传统方法的局限性.引入单片集成匹配双运放、三运放组合的思想,形成有源反馈补偿的最小相移方法,分别从电路设计、数学推导、实际参数比较及计算,详细讨论集成运放的最小相位误差组合应用技术,在指定相位误差下,可有效扩展频带.这对相位误差有着严格要求的电路与系统有着重要意义.     

Teacher and child talk in active learning and whole‐class contexts: some implications for children from economically less advantaged home backgrounds

This paper reports the experiences of 150 children and six primary teachers when active learning pedagogies were introduced into the first year of primary schools. Although active learning increased the amount of talk between children, those from socio‐economically advantaged homes talked more than those from less advantaged homes. Also, individual children experienced very little time engaged in high‐quality talk with the teacher, despite the teachers spending over one‐third of their time responding to children's needs and interests. Contextual differences, such as the different staffing ratios in schools and pre‐schools, may affect how well the benefits of active learning transfer from pre‐school contexts into primary schools. Policy‐makers and teachers should pay particular attention to the implications of this for the education of children from economically less advantaged home backgrounds.     

自闭症儿童问题行为矫正个案研究

心身机能活性运动疗法是20世纪后新兴起的一种康复疗法,最初用于肢体障碍和心理障碍两大类人群。心身机能活性运动疗法对自闭症各个方面的影响目前还处于探讨阶段。本研究运用心身机能运动疗法对一名自闭症儿童进行为期三个月的训练,比较三方面问题行为的前后变化,证明了该方法对改善自闭症儿童问题行为和提高其社会交往能力是有效的,本文还对干预过程进行了反思。     

动态电路的解法分析

本文利用解微分方程和拉普拉斯变换,对动态电路的解决方法进行分析,从而得到结论,对动态电路来讲,拉普拉斯变换是最完善的解决方法。     

2，4-二硝基苯苄醚合成的改进

采用2,4-二硝基苯酚与苄基氯为主要反应原料,在碘化钾存在下,用相转移催化剂在水相中催化合成了2,4-二硝基苯苄醚。研究了反应中催化剂、活化剂及碱的用量、反应温度以及时间等因素对产品产率的影响。最终优化了反应条件,最佳条件为：催化剂：活化剂：碳酸钾（摩尔比）=0．14：0．15：0.3;2,4-二硝基苯酚：苄基氯（摩尔比）=1．5：3．0;在70～75℃反应3．5h产品收率达到90．65％。     

股东提案制度绩效实证分析——以沪深两市上市公司为例

沪深两市上市公司股东积极利用股东提案制度参与公司治理的实践,证实股东提案制度的正当性和理论基础的现实性,为中小股东提供利益保护机制的制度目的初步实现,但尚需修正制度实践中可能影响制度价值的异化现象。     

国际公民教育的视界:主动公民身份再造

发轫于古希腊城邦时期的主动公民身份思想,随着近现代亲密性社会的兴起而日渐式微。现代社会普遍存在的民主的赤字、社会资本的销蚀和共享价值的迷失都是主动公民身份消解的后果。为了有效地应对主动公民身份消解带来的危机,西方公民教育界开展了政治性描述、理论性界定和经验性分析三种研究路径。在实践中,以全校策略框架为代表的主动公民身份再造运动更是风起云涌。然而,由于主动公民身份的再造是一个动态性的系统工程,因此其再造之路任重而道远。     

论模拟听证会在公共政策实践教学中的运用

模拟听证会是真实听证会的预演或再现,是学生通过角色扮演从而模拟政策制定过程的新模式,也是公共政策课程实践教学的重要内容。本文基于笔者的教学实践经验,结合多次使用的模拟听证会案例,分析了模拟听证会的主要模式和活动过程中存在的主要问题,提出了完善模拟听证会实践教学活动的三点建议。     

Taking active learning into the primary school: a matter of new practices?

This paper examines the extension of active learning pedagogical practices familiar in preschool settings to the first class of primary school. Policy and practice guidance in the UK is advocating the benefits of experiential learning as a way of engaging young children as they move into primary school but for teachers this means a move to new practices which can be in tension with other expectations. In this paper, the rationale for active learning is considered along with an account of the classroom activities of teachers and children in five primary schools that were implementing the policy shift to active learning. The children in these classes spent varying amounts of time in whole class activities led by the teacher or in small groups directed to engage with specific activities. They had opportunities to engage and respond verbally, through manipulating objects and with physical actions but the emphasis was on planned, teacher-directed learning activities. The characteristics of active learning as introduced in these innovative classes are compared with the expectations of practice guidance and theorising about early learning.     

一种C波段宽带二维扫描固态有源相控阵天线设计与实现

基于机载合成孔径雷达系统的具体应用,给出一种C波段宽带二维扫描固态有源相控阵天线的设计与实现方案. 该天线辐射阵面采用双层矩形微带贴片,由宽带偶极子激励. 通过增加金属隔墙和金属接地螺钉的加载来降低天线单元间互耦,实现了宽带二维相控扫描. 测试结果表明,辐射单元阵中驻波带宽(VSWR<1.6) 达到800 MHz(相对带宽约15%).