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乙酰乙酸乙酯-BR化学振荡反应的研究 总被引:2,自引:0,他引:2
本文首次报道了乙酰乙酸乙酯-IO-3-H2O2-Mn2+-H2SO4体系的化学振荡反应。研究了各种因素对振荡反应的影响,测定了最佳反应条件及振荡反应的浓度范围。研究了温度变化对振荡反应的影响,并计算了振荡反应的表观活化能,对振荡反应产物进行了分析,并测定了体系主要反应的计量关系,采用UV法对金属离子的作用和催化机理作了研究,探索了BR反应中I2的产生机理及消耗机理,对体系中有关反应物的作用作了说明。在FKN机理的基础上,对BR反应的自催化反应步骤和控制机理进行了初步的探索,并对有关实验现象作了说明。 相似文献
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新铜试剂-铜(Ⅱ)体系萃取原子吸收法间接测定微量碘的研究 总被引:6,自引:0,他引:6
本文研究了NCP-Gu(Ⅰ)·I-离子对的彤成和萃取条件,离子对的组成及其对测定灵敏度的影响。利用萃取分光光度法验证了离子对的组成,探讨了吸收峰的本质。测定了健康人血清和海带煮沸液中微量游离I-,获得了满意的结果。 相似文献
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纳米微晶纤维素(NCC)由于其大量、可再生、可生物降解以及优良的力学性能,成为纳米技术领域研究的热点。文章综述了NCC的制备方法,并对化学和机械法制备NCC纤维素作了重点介绍。同时对NCC的表面改性进行了综述。并对NCC在制备纳米复合材料领域的应用进行了总结,对其在增强复合材料中的应用作了较详细的介绍。最后对NCC未来的发展进行了展望。 相似文献
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对化学课堂教学发展性评价指标制定了操作性定义,并设计了具体观测点和测量表,拟对化学课堂教学做一个全面的、综合的发展性评价。并用该测量表对本校高二年级学生和教师做了调查,及时反馈给了教师,对本校教师的课堂教学提出了发展性的意见和建议。 相似文献
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《分析试验室》2020,(9)
基于单半导体激光器(LD)-单位敏探测器(PSD)激光对中仪,通过加装V型架和弹性带改变对中仪与传动轴的连接方式,构建了一套无需轴系转动即可完成大型机组多轴轴系对中测量的激光对中测量系统。解决了大型轴系对中测量时因盘车困难所导致的测量过程难以进行的问题。同时建立了对中仪测量数据优化计算数学模型,利用最小二乘法拟合空间直线可对调整量进行优化。该算法优化模型经三轴系样机对中测量验证,可以满足工程轴系同轴度检测要求,并且与对中仪直接获取的对中调整量相比,优化算法可将轴系调整量降低20%以上,有效改善了大型机组多轴系对中调整过程中调整量过大的问题。该测量系统及优化算法为大型机组轴系激光对中测量提供了新的解决办法,提高了对中效率,拓宽了激光对中仪的适用范围。 相似文献
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通过对负载了丁二肟的活性炭对镍的吸附和富集行为的研究,确立了活性炭负载丁二肟和其对镍的吸附洗脱条件。建立了负载丁二肟活性炭对镍富集、分离,再用原子吸收测定的分析方法。方法的富集倍率为40倍。对地表水的测定结果令人满意。 相似文献
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采用超声辅助液液萃取-气相色谱-质谱法,建立了烟用香精香料的指纹图谱。以二氯甲烷-乙醇(9+1)混合溶液为萃取溶剂,饱和氯化钠溶液为水相,超声萃取10min,对1187号烟用香精香料样品进样检测。共检出了25个组分,对其中的23个组分进行了定性。11个批次的样品色谱图显示了较高的相似性,并运用主成分分析法(PCA)区分了添加其它香精香料的掺兑样品。方法可以用于考察烟用香精香料的质量。 相似文献
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Food flavor compounds due to the complexity of food as a matrix, and usually their very low concentrations in a product, as well as their low odor thresholds, create a challenge in their extraction, separation and quantitation. Food flavor volatiles represent compounds of different polarity, volatility and chemical character, which determine method of extraction for their isolation from food. Microextraction techniques, mainly SPME and SBSE have been used for food flavor compounds analysis for two decades. Microextraction methods other than SPME and SBSE are seldom used despite their analytical potential. The review discusses the nature of food flavor compounds, and different approaches to food flavor analysis. It summarizes the use of microextraction methods in food flavor compounds analysis based on papers published in the last 5 years, and discusses the potential of microextraction methods in this field. 相似文献
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Huang LF Wu MJ Zhong KJ Sun XJ Liang YZ Dai YH Huang KL Guo FQ 《Analytica chimica acta》2007,588(2):216-223
In this paper, chromatographic fingerprint was firstly used for quality control of tobacco flavors. Based on gas chromatography-mass spectrometry (GC-MS) and combined chemometrics methods, a simple, reliable and reproducible method for developing chromatographic fingerprint of coffee flavor, one of tobacco flavors, was described. Six coffee flavor samples obtained from different locations were used to establish the fingerprint. The qualitative and quantitative analysis of coffee flavor sample from Shenzhen was completed with the help of subwindow factor analysis (SFA). Fifty-two components of 68 separated constituents in coffee flavor sample from Shenzhen, accounting for 88.42% of the total content, were identified and quantified. Then, spectral correlative chromatography (SCC) was used to extract the common peaks from other five studied coffee flavor samples. Thirty-eight components were found to exist in all six samples. Finally, the method validation of fingerprint analysis was performed based on the relative retention time and the relative peak area of common peaks, sample stability and similarity analysis. The similarities of six coffee flavor samples were more than 0.9104 and showed that samples from different locations were consistent to some extent. The developed chromatographic fingerprint was successfully used to differentiate coffee flavor from coco flavor and some little difference sample prepared with coffee flavor and coco flavor by both similarity comparison and principal component projection analysis. The developed method can be used for quality control of coffee flavor. 相似文献