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101.
ZnCl2/Si-MCM-41催化剂的制备、表征及催化性能研究 总被引:2,自引:1,他引:2
通过浸渍法制备了新型的环境友好催化剂ZnCl2/Si-MCM-41。考察了它在苯与苄氯的苄基化反应上的活性,探索了制备ZnCl2/Si-MCM-41负载试剂的最佳制备条件。研究表明:ZnCl2/Si-MCM-41的最佳制备条件是负载量为4mmol/g,活化温度为150℃,活化时间为5h。通过XRD、TG、FT-IR对催化剂进行表征,发现ZnCl2在较低负载量时,ZnCl2充分分散在载体孔道内,对催化剂载体的结构没有明显的影响,而且此负载试剂上苯的苄基化反应的活性中心不是晶体ZnCl2,而是存在于载体表面的非晶态ZnCl2物种。 相似文献
102.
对各种边界条件下初始缺陷压杆的稳定性进行了系统的研究,讨论了不同边界条件和初始挠度对压杆稳定性的影响,得出了求解弹性边界约束系数、端点转角、端点弯矩和压杆挠度的公式,为进一步的理论分析打下了基础。 相似文献
103.
支持计算机协同操作的虚拟实验室的研究开发 总被引:7,自引:0,他引:7
该文对虚拟实验室、计算机支持的协同工作(CSCW)进行一些简述。提出了研究开发基于网络协同工作的虚拟实验室的一种新视野和新思路。开发实现了一个具有协同工作能力的虚拟实验室系统。首先该系统是一个虚拟实验室系统,具有虚拟实验室的基本功能,如虚拟元器件、可视化输入、可视化输出、可视化模型等;其次它是一个网络环境下的协同工作系统,具有不同实验者之间协作完成同一实验的功能。 相似文献
104.
多媒体会议系统研究 总被引:5,自引:1,他引:5
徐时新 《小型微型计算机系统》1997,18(3):14-22
多媒体会议系统是一种典型实用的计算机支持的协同工作(CSCW)应用,最近几年发展很快,受到了广泛的重视。我们从多媒体技术和计算机网络技术两方面出发对多媒体会议系统进行系统研究,在此基础上,提出多媒体会议系统的总体设计,特别是针对多媒体会议系统的关键问题和支持多媒体网络协议存在的问题,提出了多媒体通信服务模型,以试衅弥补当前网络协议对服务质量(QOS)的不足,同时也给出了新服务模型下的参考实现框架。 相似文献
105.
Addis Michael E.; Hatgis Christina; Krasnow Aaron D.; Jacob Karen; Bourne Leslie; Mansfield Abigail 《Canadian Metallurgical Quarterly》2004,72(4):625
Eighty clients enrolled in a managed care health plan who identified panic disorder as their primary presenting problem were randomly assigned to treatment by a therapist recently trained in a manual-based empirically supported psychotherapy (M. G. Craske, E. Meadows, & D. H. Barlow, 1994) or a therapist conducting treatment as usual (TAU). Participants in both conditions showed significant change from pre- to posttreatment on a number of measures. Those receiving panic control therapy (PCT) showed greater levels of change than those receiving TAU. Among treatment completers, an average of 42.9% of those in PCT and 18.8% in TAU achieved clinically significant change across measures. The results are discussed with reference to the dissemination of PCT and other evidence-based psychotherapies to clinical practice settings. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
106.
Evidence-based practice and empirically supported treatment movements are potent forces that affect the practice of psychology today and have the potential to mandate the types of treatments psychologists conduct. The histories of these movements reveal that certain aspects of therapy valued by psychologists have been ignored. It is shown that the evidence-based movements (a) overemphasize treatments and treatment differences and (b) ignore aspects of psychotherapy that have been shown to be related to outcome, such as variation among psychologists, the relationship, and other common factors. It is important that psychologists understand the development of these movements so that they can be critical consumers of research and can effectively influence the future course of events. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
107.
Preparation of polypropylene‐based nanocomposites using nanosized MCM‐41 as support and in situ polymerization 下载免费PDF全文
Darío M González Raúl Quijada Mehrdad Yazdani‐Pedram Joao Paulo Lourenço M Rosario Ribeiro 《Polymer International》2016,65(3):320-326
MCM‐41 nanoparticles were used for preparing nanocomposites through the in situ polymerization of propylene. The performance of the catalytic system and the final properties of the materials obtained are highly dependent on the methodology used for impregnation of the catalyst onto the support particles, and therefore an optimization study for the impregnation methodology of the catalyst (Me2Si(Ind)2ZrCl2) was carried out. Two different methodologies were used; the results in terms of catalytic activity and polymer molecular masses indicated that the most promising one involved the pre‐activation of the catalyst with the cocatalyst, methylaluminoxane, followed by impregnation onto the MCM‐41 nanoparticles. Thus, an optimized route for the preparation of polypropylene nanocomposites achieving significant improvements in catalyst activity was developed. The nanocomposite materials were characterized by GPC, TGA and DSC. The dispersion state and the size of the nanoparticles incorporated in the polypropylene matrix were investigated by transmission electron microcopy. Additionally, this methodology allows simultaneous control of the desired amount of support and the concentration of catalyst to be used in the in situ polymerization. © 2015 Society of Chemical Industry 相似文献
108.
Recent advances in the production of γ‐valerolactone from biomass‐derived feedstocks via heterogeneous catalytic transfer hydrogenation 下载免费PDF全文
Amin Osatiashtiani Adam F Lee Karen Wilson 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2017,92(6):1125-1135
γ‐valerolactone (GVL) is an important intermediate chemical with a wide range of applications as fuel, fuel additive and as a green solvent which has received a great deal of attentions from both academia and industry. This review aims to summarise the advances in conversion of renewable feedstocks into GVL through heterogeneous catalytic transfer hydrogenation (CTH) with a strong emphasis on discussing preparation, characterisation and performance of the catalysts in order to provide a better understanding of various catalytic systems and also to compare them in terms of catalytic performance. © 2017 Society of Chemical Industry 相似文献
109.
110.
《International Journal of Hydrogen Energy》2021,46(67):33523-33540
The metal-supported solid oxide fuel cell (MS-SOFC) is of current research interest in the clean energy field due to its high performance, quick start-up, thermal cycle stability, and lower raw material cost compared to the conventional cermet-based SOFC. To efficiently operate a MS-SOFC using complex hydrocarbon and logistic fuels, it is required to introduce an internal reforming catalyst within the anode metal scaffold. This review article discusses some examples of the performance of MS-SOFCs under hydrocarbon and logistic fuels with and without an additional reforming catalyst. We also discuss the performance improvement of conventional cermet-based SOFCs by adding reforming catalysts via the infiltration method. This information can be directly applied to future MS-SOFC applications. Furthermore, this review article proposes possible novel methods such as direct precursor infiltration, catalyst-anode premixing, and atomic layer deposition methods to introduce the reforming catalyst into a MS-SOFC for improving its initial electrochemical performance and long-term stability under hydrocarbon and logistics fuel. 相似文献