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41.
The reactions of a variety of activated vinyl compounds with cotton cellulose fabric containing quaternary ammonium hydroxide substituents were explored. Each reaction, catalyzed by the basic groups in the cellulose, was followed to or near the point of leveling off. The results are analyzed and discussed in terms of accessibility of the cellulosic compositions and in terms of the efficiency of the quaternary ammonium substituents as catalysts for the addition reactions. Estimates of relative forward rate constants (kf) and equilibrium constants (K) for the reactions were made. The values of kf for reactions of the vinyl compounds with the quaternary ammonium celluloses show a relative order which is similar to that for the reactions of the vinyl compounds with simple alcohols. Evidence is presented to indicate that, in some cases, the addition of vinyl compounds is accompanied by anionic-catalyzed graft polymerization. 相似文献
42.
Lent Robert W.; Hoffman Mary Ann; Hill Clara E.; Treistman Dana; Mount Mandy; Singley Daniel 《Canadian Metallurgical Quarterly》2006,53(4):453
Two versions of a counselor self-efficacy (CSE) measure were administered to 110 prepracticum counselors: a general version, assessing perceived capability to perform basic helping skills and manage the session process with clients generally; and a client-specific version, tapping capability to perform the same behaviors with a specific, current client. Client-specific CSE was found to (a) relate moderately to strongly with general CSE over the course of four counseling sessions, (b) increase significantly over sessions, and (c) account for unique variance in counselors' evaluations of the quality of their sessions. Although it was not a useful direct predictor of clients' session ratings, higher client-specific CSE was associated with greater congruence between counselors' and clients' perceptions of session quality. Implications for further research and training are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
43.
A learning environment to support mechanical reasoning and understanding of simple machines for middle school and high school students is presented, along with results of an evaluation of its effectiveness in student learning. Based on recommendations from literature on instructional frameworks and cognitive aspects of mechanical reasoning, SIMALE (the Simple Machines Learning Environment) was designed to support reflection, collaboration, and presentation of concepts from multiple perspectives. SIMALE was implemented with a diverse population of middle and high school students with three treatment variations: (1) environment with focus on Lego exercises to engage in hands‐on physical activities, (2) environment with focus on a Web‐based computer module, and (3) environment with both the computer module and Lego exercises. Analyses of results show significant increases in post‐test performance for all treatment variations within SIMALE. The results also revealed unexpected dramatic results in equalizing post‐test scores along ethnic and gender dimensions, in spite of large population differences in pre‐test scores. 相似文献
44.
45.
Over the last several years, engineering faculty and learning scientists from four universities worked in collaboration to develop educational materials to improve the quality of faculty teaching and student learning. Guided by the How People Learn (HPL) framework, engineering faculty worked in collaboration with learning scientists to develop learner‐centered, student‐focused instructional methods. In consultation with learning scientists, engineering faculty carried out educational inquiry in their classrooms aimed at investigating student learning and enhancing instruction. In this paper we discuss the extent to which faculty engaged in these collaborative endeavors and how their teaching approaches differed as a result of their level of engagement. Study findings reveal the role that collaborative reflection plays in shaping teaching approaches. Results from this study provide insights for researchers and other practitioners in engineering and higher education interested in implementing engineering faculty development programs to optimize the impact on teaching. 相似文献
46.
Ann Eggington 《Journal of Low Temperature Physics》1977,28(1-2):1-14
The influence of substrate potentials on the superfluid density in thin films of4He atT=0 is discussed. Estimates indicate that an observabl large reduction in s is to be expected. 相似文献
47.
目的 分析2017年广州市一起副溶血性弧菌食物中毒分离株的特征.方法 采用血清型鉴定,药敏实验,毒力基因(tdh、trh、tlh)、toxRS/new基因、orf8基因的聚合酶链式反应(PCR)检测,脉冲场凝胶电泳(PFGE)和多位点序列分型(MLST)进行分析.结果 14株副溶血性弧菌血清型鉴定为O8∶K21,药敏试... 相似文献
48.
对采用不同换热器配置的有机朗肯循环(ORC)系统进行了分析,理论分析结果表明:在柴油机烟气余热ORC系统所有部件之中,蒸发器的损失最大;通过增加预热器或回热器能进一步提高热源的利用率,但同时系统的损失和成本增加。为此对影响ORC系统性能的关键因素进行优化设计:使蒸发器过热度和冷凝器的过冷度取1~2℃;并尽可能提高膨胀机的膨胀比和内效率。试验结果表明:ORC试验系统理论热效率5.7%,实际热效率5.3%,引起偏差的主要原因是膨胀机实际容积效率低于理论值,实际机械消耗大于理论值,且系统混入的不凝气也对系统造成影响。新开发的低温烟气余热ORC系统的设计方法,实现了对烟气余热ORC系统的优化配置,为船舶柴油机烟气余热利用提供了一种切实可行的解决方案。 相似文献
49.
电池的使用寿命不够长是电子书、PDA 等之类的便携式显示应用的一个重大问题.电池的功耗一方面取决于其制作工艺,另一方面还与显示器的驱动有关.优化显示器的驱动可以降低其功耗.文章介绍了一种智能型驱动,通过对其每个图像的行列波的计算可知其功耗降低了 50%. 相似文献
50.