走进添加剂世界

正确看待食品添加剂《中华人民共和国食品安全法》第九十九条对食品添加剂定义为:食品添加剂,指为改善食品品质和色、香、味以及为防腐、保鲜和加工     

解析一道与铁有关的实验题

题目 （2005年上海高考题）硫酸铁（PFS）是一种新型高效的无机高分子絮凝剂，广泛用于水的处理，现以铁的氧化物为原料来制取聚合硫酸铁，为控制水解时Fe^3＋的浓度，防止生成氢氧化铁沉淀，必须先将原料中的Fe^3＋还原为Fe^2＋，制取步骤如下：     

对羧基苯偶氮硫代若丹宁固相萃取光度法测定烟草及其添加剂中的汞

研究了对羧基苯偶氮硫代若丹宁 (CPATR)与汞的显色反应,在pH为3.5的醋酸-醋酸钠缓冲介质中,吐温-80存在下, CPATR与汞反应生成2:1稳定络合物,该络合物可被Waters Sep-Pak C18小柱固相萃取,用氮-氮二甲基甲酰胺(DMF)洗脱后用光度法测定,在洗脱液介质中,λmax＝535 nm,体系摩尔吸光系数达8.70×103 m2/mol. 汞的质量浓度在0.05～4.0 mg/L内符合比尔定律. 该方法可用于烟草及其添加剂中汞含量的测定,结果满意.     

《高分子纳米材料》课程教改研究与探索

《高分子纳米材料》是我校高分子材料专业开设的一门专业选修课。在分析了课程的目的、特点和教学存在问题的基础上,详细阐述了运用视频课程、颠倒课堂、电子产品辅助教学等多元化教学手段,实现本课程的教学改革。     

应用化学教学中环境化学教育的渗透

环境化学教育对于高校学生非常重要,在应用化学教学中可结合有关环境问题适时进行环境教育的渗透,既可以增强学生的环保意识,又可以巩固所学知识,进一步激发学习兴趣。     

木聚糖酶的稳定性研究

本文研究了木聚糖酶的稳定性及最适温度和最适pH值。结果发现，木聚糖酶具有较差的热稳定性和较好的pH值稳定性。其最适温度为50℃，最适pH值为4．2。     

浅谈高分子材料专业英语教学中学生学习兴趣的培养

《高分子材料专业英语》是高分子材料科学与工程专业的专业基础课,其目的是培养学生以英语为工具解决高分子材料专业学习中的实际问题的能力,为学生专业知识学习和今后的科学研究和工作奠定基础。在《高分子材料专业英语》教学中,有目的地培养学生的学习兴趣是促使学生学好专业英语的最好办法。本论文从教学内容、教学方法以及教学手段等方面入手,浅谈在《高分子材料专业英语》教学中如何培养学生的学习兴趣。     

高分子材料的催化合成

介绍了常见的与高分子合成化学反应有关的化学催化、物理催化和生物催化的类型、特点和应用。     

Effect of Mixed Solvents and Additives on the Habit Modification of 6-APA Crystals

6-aminopenicillanic acid (6-APA) crystals obtained under different physical and chemical conditions of the solutions may present different habits. The habits of diamond-shaped plates are desirable compared with other habits of 6-APA crystals. To obtain ideal 6-APA crystals, the effects of the mixed solvents and additives on 6-APA crystal habits were investigated. Ethanol or acetone was used as the organic solvent, and impurities existing in the ,6-APA purification process were used as the additives. 6-APA growth habits were changed when the concentrations of ethanol, acetone or phenyl acetic acid were increased to exceed their critical concentration. The observed results show that the dominant face on 6-APA crystals was identified to be , {020}, but the overall habit was controlled by the relative growth rates of the : 101 and {002} faces. Crystal growth rates and habits can be appreciably changed by specific adsorption of additives on crystal faces. In some cases solvent molecules can act in a similar way and may be regarded as bulk additives. The effects of additives and organic solvents on 6-APA crystal habits were the results of adsorption effect,which fitted the experimental results quite well.