低成本ZSM-5型沸石分子筛的合成及其吸附性能

以廉价的工业废弃物粉煤灰作为初始原料,四丙基氢氧化铵（TPAOH）为模板剂,分别采用两种合成方案制备出微孔分子筛ZSM-5样品。该法相较传统水热法,原料价廉易得,制备工艺简单。通过XRD、SEM、TR等手段对样品进行表征,发现两种方案均合成出了较高质量的ZSM-5,但形貌分别为薄片型和长六方体型。最后考察了其对水中Cr（Ⅵ）离子的吸附性能,结果表明合成的ZSM-5型样品对Cr（Ⅵ）离子有较好的吸附性能。     

乙酰苯胺制备的绿色化研究

采用苯胺和冰醋酸(乙酸酐)为原料,通过分馏法、回流法、干燥法、回流-干燥法、微波辐射法合成了乙酰苯胺.从绿色化学理念出发,进行反应方法探究和比较,优选出合理、实用、可行的制备方法.回流-干燥法和微波法是较佳的合成方法,不仅操作简便,反应时间缩短,而且提高了反应产率,使实验操作更加绿色化,也可为探究性实验的设计提供借鉴.     

苏氨酸氮甲基化及量子化学计算研究

采用还原胺化法将苏氨酸成功转变成了其氮二甲基衍生物,通过1H-NMR和13C-NMR证实了其结构,采用量子化学方法在DFT-B3LYP/6-31G*水平上计算了该化合物的反应热、电荷分布和前线轨道能级。     

Study on the reactions of azo compounds with acyl halides mediated by Sm/TiCl4

INTRODUCTION Amides are important commercial and biologi-cal compounds. Because amides constitute the backbone of protein molecules, their chemistry is of extreme importance. The penicillin and cephalosporin antibiotics are among the best-known products of the pharmaceutical industry. For this reason, the devel-opment of new and simple methods for the synthesis of the peptide bond always constitute an important addition to the field of natural products synthesis. Several general methods …     

天然高分子甲壳素类纤维的研究进展

综述了甲壳素及其衍生物纤维的制备和性能.介绍了制备甲壳素纤维的黄化法、含卤溶剂法和酰胺-氯化锂法.总结了壳聚糖纤维制备的一般方法和性能.简要介绍了甲壳素/壳聚糖酯类和醚类衍生物的纤维.讨论了甲壳素类纤维的应用.     

氯化钯和氯化铜催化炔烃卤钯化环化反应的应用研究

卤钯化反应是有效地构建多种生理活性药物、有机功能小分子以及合成骨架的重要途径,在有机合成上有着非常广泛的应用。通过综合整理,对近几年来氯化钯和氯化铜催化炔烃环化反应合成含氧杂环化合物和含氮杂环化合物等两方面的最新研究进行综述。     

硫脲衍生物的研究进展

本文介绍了硫脲衍生物的合成方法,以及它在农业、医药、工业和分析化学等方面的应用,并对其在这几方面的发展前景进行了展望.通过对硫脲衍生物的合成方法及应用的综述,从而为生产和研究提供新的思路.     

Case Study Research: Establishing Entry Requirements Across Career Fields

This article describes and illustrates a new way of establishing entry criteria for air force career fields. It allows for direct comparisons across different career fields, is more objective, much less time‐ and labor‐intensive, and more flexible with regard to criterion setting than are previous methods. In addition, it is easier to update in light of career field changes than are previous approaches based on benchmarking task difficulties. It could also easily be extended beyond its original military application to civilian and other governmental applications by using a variety of predictor and criterion variables to build the models.     

高分子网络法制备In2O3超细粉的工艺研究

以硝酸铟为起始原料, 利用高分子网络法合成纯的单相In2O3纳米晶. 采用X射线粉末衍射(XRD)和透射电镜(TEM)等检测手段对所得粉体的组成、大小和微观形貌进行了表征和分析. 同时, 根据XRD衍射图谱结果进一步讨论了不同原料质量浓度、煅烧温度和煅烧时间对产物粒径的影响. 实验结果表明所得晶粒晶相单一, 粒度均匀并且可以选择适宜的条件制备所需粒径的纳米氧化物.     

Novel Method for Preparing a Carbon Nanotube-Supported Cobalt Catalyst for Fischer–Tropsch Synthesis:Hydrogen Dielectric-Barrier Discharge Plasma

Hydrogen dielectric-barrier discharge (H₂-DBD) plasma was successfully used to prepare carbon nanotubes (CNTs)-supported cobalt (Co) catalyst. The H₂-DBD plasma treatment simultaneously decomposed and reduced the cobalt precursor at a lower temperature and in a shorter time than the conventional method (calcination and hydrogen reduction). It is considered that the H₂-DBD plasma method can remarkably decrease the amount of energy input compared to traditional methods used to prepare the Co-based catalyst in Fischer–Tropsch synthesis (FTS). Results showed that the Co catalyst prepared by H₂-DBD plasma had an equivalent catalytic performance for FTS as that prepared using the conventional method in calcination and hydrogen reduction, thereby determining that H₂-DBD plasma was an effective alternative treatment for preparing the Co/CNTs catalyst for FTS. This technology will provide a new strategy for preparing catalysts in other catalysis processes.     

Fluorine-Mediated Benzothiadiazole Derivatives for Second-Order Nonlinear Optics

With increasing research interests in the field of light-matter interactions,various methods have been developed for regulating nonlinear optical (NLO) materials.However,the design and synthesis of organic molecular materials for second-order nonlinear optics remain a great challenge because of the strict requirement of the materials to possess a noncentrosymmetric structure.In this work,two benzothiadiazole (BTD) derivatives referred to as BTD-H and BTD-F were synthesized,and their NLO properties in the crystalline states were studied.It was found that introducing fluorine into the BTD backbone effectively tuned the crystal packing styles of BTD derivatives to a noncentrosymmetric system for effective second-order NLO responses.Such a strategy to induce the noncentrosymmetric structure by introducing the fluorine atoms and halogen interactions may provide guidance for future engineering of organic NLO molecular materials.     

新形势下职业院校体育教材建设研究

采用文献资料、专家访谈、逻辑分析等方法,对新的人才培养模式下职业院校体育教材建设进行了探讨。找出了存在的主要问题,提出了以岗前职业健康安全教育为切入点,更新教材内容;创新教材呈现形式;开发校本教材;更改体育课程名称等建议。     

嘧啶水杨酸类除草剂中间体2-氯-4,6-二甲氧基嘧啶的合成研究进展

综述了国内外近年来农药中间体2-氯-4,6-二甲氧基嘧啶的合成研究进展.介绍了以丙二睛、硝酸胍与丙二酸二乙酯为原料的合成工艺路线和研究水平.分析比较了各种合成方法的优缺点,展望了合成2-氯-4,6-二甲氧基嘧啶的工业化发展前景.     

绿色化合成环己烯实验的探索

以环己醇为原料,FeC l3.6H2O催化合成环己烯,探讨了催化剂的用量和反应时间对实验结果的影响。结果表明:此法环己烯收率可达86.1%,纯度为98.6%,催化剂价廉易得,实验过程简单、环保,是一条合成环己烯的典型绿色途径。     

Personalized recommendation of learning material using sequential pattern mining and attribute based collaborative filtering

Material recommender system is a significant part of e-learning systems for personalization and recommendation of appropriate materials to learners. However, in the existing recommendation algorithms, dynamic interests and multi-preference of learners and multidimensional-attribute of materials are not fully considered simultaneously. Moreover, these algorithms cannot effectively use the learner’s historical sequential patterns of material accessing in recommendation. For addressing these problems and improving the accuracy and quality of recommendation, a new material recommender system framework based on sequential pattern mining and multidimensional attribute-based collaborative filtering (CF) is proposed. In the sequential pattern based approach, modified Apriori and PrefixSpan algorithms are implemented to discover latent patterns in accessing of materials and use them for recommendation. Leaner Preference Tree (LPT) is introduced to take into account multidimensional-attribute of materials, and learners’ rating and model dynamic and multi-preference of learners in the multidimensional attribute-based CF approach. Finally, the recommendation results of two approaches are combined using cascade, weighted and mixed methods. The proposed method outperforms the previous algorithms on the classification accuracy measures and the learner’s real learning preference can be satisfied accurately according to the real-time up dated contextual information.     

“一锅法”合成N-叔丁氧羰基哌嗪脲

芳胺在-5℃的条件下先与三聚光气作用后,再与单保护的N-叔丁氧羰基哌嗪反应,＂一锅法＂高效简便地生成了N-叔丁氧羰基哌嗪脲。反应以乙腈作溶剂,三乙胺作碱,反应温度和投料顺序对反应产率有很大影响。     

L-肉碱的微生物酶合成法研究进展

L-肉碱具有许多重要的生理功能,被广泛应用于医药、食品及饲料添加剂中.综述以各种不同的物质为底料,通过各种微生物及其产生的酶的催化,在不同的工艺条件下合成L-肉碱的方法,同时也讨论了各种微生物及酶合成法的优缺点.     

苯并-15-冠-5缩氨基硫脲类化合物的合成方法研究

叙述了9个苯并-15-冠-5缩氨基硫脲类化合物在以乙醇为溶剂,浓盐酸为催化剂回流与微波辐射条件下的合成方法研究。结果表明其中只有2个化合物e和h适合于高温回流和微波辐射条件下进行反应,其它化合物出现了分解或变质现象。对于化合物e和h,在微波辐射条件下进行反应时,仅仅3分钟,反应几乎定量完成,是目前发现的最高效的合成方法。     

关于备课的几点思考——浅谈语文教师备课的现状及策略

在课改的大潮中,如何更有效地提高语文课堂的教学效率,是每一位语文教育者共同的话题。备课的水准直接影响教学的质量。而当前教师备课的现状是照抄照搬,一成不变;上网搜索,"拿来主义"成风;问题设置蜻蜓点水,浅尝辄止。对于备好课有几个策略,即备好自己,做到教学合一;备好学情,了解学生的内心世界;备好教材,制定教学策略;备教法,切中教学的契合点;备反思,促进教师专业成长。