共查询到20条相似文献,搜索用时 156 毫秒
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包装工程专业属于多学科交叉学科,涉及材料科学与工程、食品科学与工程、机械工程、艺术等多门学科。《高分子材料基础》属于包装工程专业的基础理论课之一。本文通过分析高分子材料相关知识与《包装材料学》、《包装技术》、《包装印刷》等主干课程的关系,明确了《高分子材料基础》课程在包装工程专业中的地位与作用;根据包装工程专业的知识结构、要求及当前课程设置,选择教材并梳理了课程的教学重点;针对包装工程专业学生化学基础薄弱的特点,提出几点教学方法。 相似文献
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Four titanocene complexes were prepared in aqueous or two-phase medium by the reaction of benzoylacetone titanocene with substituted salicylic acid, respectively. Based on the UV-Vis spectra, we studied the accelerating effect of the benzoylacetone on the reaction rate quantificationally. The results demonstrated that the presence of it not only stabilizes the “Cp2Ti” species and accordingly makes pH value of the aqueous solution of substituted salicylic acid increased but also prompts the reaction due to the presence of its conjugation structure and oleophyllic group. Furthermore, the presence of benzoylacetone is in favor of the simplification of the products. 相似文献
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将固体进样装置与电感耦合等离子体发射光谱仪(ICP-SSEA)联用,采用固体进样,直接测定铸铝合金中的铜、铁、镁、锰、镍、钛、硅、锌等元素含量。研究表明,该法与火花光谱法比较,具有很宽的的动态范围,测量精度和普通化学分析方法相当,同时又有火花光谱分析的速度。能满足工厂冶炼控制的要求。 相似文献
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石墨相氮化碳(g-C3N4)是一种新型的无金属材料,因其具有众多特殊的理化性质,在多相催化、光催化、燃料电池和气体储存等领域显示出了潜在的应用前景。与直接热聚合法制得的块状g-C3N4相比,介孔g-C3N4拥有高比表面和丰富的介孔孔道,能暴露更多的表面活性位,继而提升其在催化反应等应用方面的性能。热聚合法是合成g-C3N4的最为便利的方法。其中,热聚合法合成介孔g-C3N4的工艺分为硬模板法、软模板法和无模板法。本文对近十年来国内外这三种合成工艺的研究进展进行了综述。特别是针对硬模板法,从前驱体合成机理、产品理化性质等多角度评述了硬模板法合成介孔g-C3N4的关键问题。此外,针对新型的软模板法和无模板法进行了介绍,并与硬模板法进行了细致的对比和讨论。最后,对介孔g-C3N4合成工艺的未来发展趋势进行了展望。 相似文献
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B. V. L’vov 《Journal of Thermal Analysis and Calorimetry》2008,92(2):639-642
The apparent increase of the reaction enthalpy ΔH with temperature due to the self-cooling and condensation effects is responsible for the fundamental restrictions of the
second-law and Arrhenius plot methods related to determination of this parameter. Theoretical analysis and a comparison with
the experimental data indicate that the systematic underestimation of ΔH magnitudes determined by the second-law method equals 10–25% for the reactants decomposed to gaseous products and 15–50%
for reactants decomposed to solids. Therefore, the use of these methods in decomposition kinetics is hardly acceptable. The
replacement of the Arrhenius plot and second-law methods to the much more precise and accurate third-law method is desirable
or even obligatory. 相似文献
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Pyrimidine derivatives have been found to possess a broad spectrum of biological activities. Among various pyrimidine derivatives, bis-pyrimidine seems to be the rarely studied. A variety of methods have been reported for the preparation of this class of compound. However, in spite of their potential utility, some of the reported methods suffer from drawbacks such as long reaction times, cumbersome product-isolation procedures, and environmental concerns. Organic reactions in aqueous media have attracted increasing interest recently because of environmental issues and the understanding of biochemical processes. Ultrasound has increasingly been used in organic synthesis for greater yields, shorter reaction times or milder conditions. 相似文献
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问题、项目引领式教学法可分为问题引领式与项目引领式教学两个部分。问题引领式教学法可用于课程的基础部分教学;项目引领教学法主要用于学生已掌握一定的基础知识之后,教师有针对性地提出一些目前亟待解决的小的项目让学生提出思路及解决办法。通过两种方法的互相补充,可显著提高学生对有机化学这门课程的学习兴趣,也能使有机化学的理论知识与实践能力更紧密地联系在一起,从而提高该课程的教学效果,同时也激发学生创新的潜能。 相似文献
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对测定食品中微量元素硒的前处理方法(干法、湿法、微波消解法等)和检测方法(原子光谱法、分子光谱法、色谱法、电化学法等)的现状(主要在1990~2010年间发表的文献)及相关的原理和方法的特点之处作了综述(引用文献20篇)。 相似文献