介孔Ce-MCM-41的合成及光催化降解活性研究

以十六烷基三甲基溴化铵（CTAB）为模板剂,采用水热合成法制备了稀土金属离子Ce掺杂的六方相有序介孔材料Ce-MCM-41,并用N2吸附、XRD、FT-IR、UV-Vis对样品结构进行了表征,将该材料用于模拟太阳光（500W氙灯）照射下甲基紫和亚甲基蓝两种染料的光催化降解研究,研究结果表明,该材料能显著降解上述两种染料,光催化降解效率高达82.4％和75.4％,具有很好的应用和开发前景.     

Role of vitamin B12 on methylmalonyl-CoA mutase activity

Vitamin B₁₂ is an organometallic compound with important metabolic derivatives that act as cofactors of certain enzymes, which have been grouped into three subfamilies depending on their cofactors. Among them, methylmalonyl-CoA mutase (MCM) has been extensively studied. This enzyme catalyzes the reversible isomerization of L-methylmalonyl-CoA to succinyl-CoA using adenosylcobalamin (AdoCbl) as a cofactor participating in the generation of radicals that allow isomerization of the substrate. The crystal structure of MCM determined in Propionibacterium freudenreichii var. shermanii has helped to elucidate the role of this cofactor AdoCbl in the reaction to specify the mechanism by which radicals are generated from the coenzyme and to clarify the interactions between the enzyme, coenzyme, and substrate. The existence of human methylmalonic acidemia (MMA) due to the presence of mutations in MCM shows the importance of its role in metabolism. The recent crystallization of the human MCM has shown that despite being similar to the bacterial protein, there are significant differences in the structural organization of the two proteins. Recent studies have identified the involvement of an accessory protein called MMAA, which interacts with MCM to prevent MCM’s inactivation or acts as a chaperone to promote regeneration of inactivated enzyme. The interdisciplinary studies using this protein as a model in different organisms have helped to elucidate the mechanism of action of this isomerase, the impact of mutations at a functional level and their repercussion in the development and progression of MMA in humans. It is still necessary to study the mechanisms involved in more detail using new methods.     

项目教学法在单片机教学及实训中的应用探讨

介绍了项目教学法在单片机教学及实训中的应用。在单片机教学及实训中采用项目教学法,有利于激发学生的学习兴趣,提高学生分析问题、解决问题的能力,有利于进一步提高学生的动手能力和综合能力,从而提高教学质量。     

MCM-41分子筛负载磷钨酸催化H2O2氧化环已酮/环已醇合成己二酸

在无溶剂、无相转移催化剂条件下,用磷钨酸做为催化剂。先用MCM-41分子筛作为催化剂载体,30%H2O2作氧源,在一定条件下可以将环已醇/环己酮混合物氧化成己二酸。讨论了30%H2O2的量、反应时间、反应温度、催化剂用量、草酸对己二酸产量的影响,以及催化剂回收重复利用。结果表明：用MCM-41分子筛负载80%的磷钨酸作催化剂反应7h,己二酸的最大产率高达89.17%。具有很好的应用价值。     

Is parental involvement lower at larger schools?

Parents who volunteer, or who lobby for improvements in school quality, are generally seen as providing a school-wide public good. If so, straightforward public-good theory predicts that free-riding will reduce average involvement at larger schools. This study uses longitudinal data to follow families over time, as their children move from middle schools to high schools, thus netting out unobservable differences among families. Increases in school size result in significant reductions in parental involvement, although the magnitude of the effect is small. If parents experience a doubling in school size, they are 2 percentage points less likely to increase their contacts with the school, and 5 percentage points less likely to increase their volunteering. A continuous-treatment propensity-score method tests whether the results are driven by selection into treatment. The parental contact results are robust to this test, while the volunteer results are not. Also, there is some evidence that parents see their involvement as a substitute, rather than a complement, for perceived school quality.     

“互联网+”视域下大学生就业指导及价值取向引导策略研究

在信息化时代中如何利用信息技术做好大学生就业指导工作是对高校就业工作者的重要挑战。当前,“互联网+”视域下,应从思想引领、顶层设计、跟踪服务等方面研究大学生就业价值取向引导和就业指导的有效策略,引导大学生树立正确的就业观,提升就业竞争力。     

从近两届世界大赛看男子竞技体操发展趋势

通过文献资料、录像观察与数理统计等方法,系统分析了当前世界男子竞技体操运动各单项的发展趋势。结果表明单项比赛的竞争更加激烈。指出在今后的训练中,应突破重点项目,发展难、新、美动作,加强运动员动作的规范性和完成动作的稳定性训练,＂以老带新＂、＂以赛代练＂,注重心态把握。     

大学生信息行为与影响因素探究——以大学生数学建模团队为例

[目的/意义] 基于实证调查分析,探究大学生数学建模团队信息行为特征、信息行为模型及其影响因素,为提高大学生数学建模团队信息素养和创新能力提供科学参考。[方法/过程] 以大学生数学建模团队为研究单元,通过对数学建模团队信息行为的参与式观察和深度访谈获取个案数据,主要采用话语分析法和归纳性内容分析法对数据进行挖掘分析。[结果/结论] 大学生数学建模团队以电子信息需求为主,信息查寻以专业数据库为主、搜索引擎为辅;主要通过全文或关键词检索方式来进行文献检索;通过结果分享模式实现团队合作信息查寻;偶遇信息利用对问题解决和数学模型质量起重要作用;大学生数学建模团队信息行为有其一般行为模型。     

第41届世界体操锦标赛男子体操比赛成绩分析

通过对第41届体操锦标赛男子体操比赛成绩的统计,分析了世界体操强国在新规则下的整体实力,了解目前各体操强国的现状,为中国体操队实现2012年伦敦奥运会夺取更多的金牌提供参考。     

MCM-41中孔分子筛的全微波法合成及其表征

中孔分子筛的合成已进入了一个全新的时期,合成方法日新月异。本文首次在不需任何助表面活性剂的条件下,用全微波的合成方法（即ＭＣＭ－４１的合成和模板剂的烧除均在微波辐射的条件下完成）合成了ＭＣＭ－４１中孔分子筛,并应用ＸＲＤ、ＩＲ、ＴＧ和ＳＥＭ等方法对样品进行了表征。结果显示,此法比以往常规水热合成法具有合成时间短,晶化时间１０－１５ｍｉｎ,焙烧模板剂１ｈ左右。所得产品晶粒分布均匀,晶形以球状为主,晶粒大小约１０μｍ等优点。全微波合成法工艺简单,操作方便,产品收得率高,它将为ＭＣＭ－４１中孔子筛的快速合成探索出新的途径