共查询到20条相似文献，搜索用时 859 毫秒
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十二烷基硫酸钠是阴离子硫酸酯类表面活性剂的典型代表,具有广泛的用途。十二烷基硫酸钠的合成制备是常见的化工专业实验,但存在合成时间长、产率低、产品稳定性差的缺点。该文对氨基磺酸法合成十二烷基硫酸钠专业实验进行了研究,在保证产率的基础上有效缩短了实验时间,并结合产品的提纯、分析和表征提高实验的综合性。 相似文献
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采用非水溶剂的合成方法制备了四碘化锡，考察了影响制备反应的因素．以四氯化碳为溶剂，反应温度为85—90℃，反应时间105min，Sn的转化率可达到99．7％．产品提纯后，经差示扫描量热计分析，其熔点为145．75℃．测定了Snh在几种溶剂中的溶解度，并制作了Snh在丙酮溶剂中的溶解度曲线． 相似文献
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制备甲醛捕捉剂乙烯脲,并研究其在不同条件下清除甲醛的效率.实验中以乙二胺和尿素在回流条件下反应制备了乙烯脲,采用高温蒸发冷凝结晶的方法对制得的固体产物提纯.对提纯后的产物进行熔点测试,乙烯脲的理论熔点133℃,测得产物的熔程132—133℃,与理论值相仿;对产物进行红外光谱分析,谱图表明产物确系为乙烯脲.实验对该产物进行了模拟除醛效率测试,测试发现,常温下质量百分浓度为8%的乙烯脲在4h内对甲醛吸收率为86.5%,效果明显. 相似文献
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采用煅烧溶解再结晶方法净化提纯二苯甲酰甲烷工业生产过程中产生的大量副产物氯化钠,充分氧化副产物表面的有机物,使其转变为水和二氧化碳,工艺流程简单,操作方便。实验研究表明在560℃-580℃温度范围内煅烧20min左右,煅烧后的样品溶液在60℃条件下水浴加热1h,溶液稳定脱色率大于98%;过滤后的澄清液经浓缩结晶,过滤干燥,制取提纯工业盐氯化钠固体,其质量可达到国家工业盐一级品标准;过滤后的母液可循环使用溶解下一批原料,无废水产生。该研究成果不仅解决了副产物氯化钠的固体废弃物污染,而且还回收大量有用资源。 相似文献
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L-抗坏血酸-2-磷酸酯镁是-种稳定的维生素C衍生物，是维生素C转化的较好途径．通过改进合成反应的催化剂减少副产物使提纯工作简化．最佳提纯工艺条件为溶液pH值6．2，搅拌脱色最佳时间1．5h，最佳搅拌温度40℃． 相似文献
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油脚中混合脂肪酸的提取及其综合利用 总被引：1，自引：0，他引：1
将菜籽油脚经皂化、酸化、水洗后制得粗脂肪酸,再经离心分离进一步提纯得到纯度较高的脂肪酸.主要考察了影响脂肪酸得率的各项因素,确定了菜籽油脚提取混合脂肪酸的最佳工艺条件:反应温度100℃,反应时间6h,加碱量9%.最佳条件下,混合脂肪酸的得率可达45%.利用酸催化法将提纯后的混合脂肪酸合成脂肪酸甲酯.通过实验找出了影响脂肪酸转化率的各种因素,确定了最佳工艺条件:反应温度65℃,反应时问6h,n(醇):n(酸)=5:1,催化剂用量2%.在此条件下脂肪酸转化率可达97%. 相似文献
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研究物理化学实验异丙醇-环己烷废液的回收提纯方法,先以水为萃取剂,对异丙醇-环己烷混合物进行萃取分离,得到粗环己烷和异丙醇水溶液,经精馏提纯得到纯环己烷和含有少量环己烷的异丙醇,环己烷精制后纯度达99．3％～99．67％,收率69．5％,萃取后的异丙醇水溶液经精馏脱水后可以制成无水异丙醇,纯度达98．42％,一次性收率在67．02％． 相似文献
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孙捷 《中学生数理化(高中版)》2012,(7):71-71
分离和提纯物质就是要去除杂质，在解答物质的分离和提纯试题时，选择试剂和实验措施应注意：（1）不能引入新杂质，（2）提纯后的物质成分不变，（3）实验过程和操作方法简单易行． 相似文献
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采用自蔓延高温还原合成法，以化学纯B2O3，TiO2和金属镁粉为原料，制备了TiB2陶瓷粉料，研究B2O3-TiO2-Mg合成系统在加热过程中的物理化学变化规律及TiB2陶瓷粉料的化学清洗提纯过程。结果表明：B2O3-TiO2-Mg体系在加热过程中合成反应分两步完成，首先是Mg从B2O3和HiO2中还原出单体元素Ti和B，然后是单体元素Ti和B发生合成反应生成TiB2；粉料的化学清洗提纯最佳条件是用2．0mol／L盐酸过量40％，加热至60℃左右清洗1．5h，可得到几乎纯净的TiB2陶瓷粉料。 相似文献
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邱崇丙 《唐山师范学院学报》2014,(1):21-23
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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Rachel Zupek 《海外英语》2007,(11):40-41
我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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YANGShiguo 《重庆大学学报(英文版)》2004,3(1):86-88
The problem on the geometrc inequalities involving an n-dimensional simplex and its inscribed simplex is studied. Aninequality is established, which reveals that the difference between the squared circumradius of the n-dimensional simplex andthe squared distance between its circumcenter and barycenter times the squared circumradius of its inscribed simplex is not lessthan the 2(n-1)th power of n times its squared inradius, and is equal to when the simplex is regular and its inscribed siplex is atangent point one. Deduction from this inequality reaches a generalization of n-dimensional Euler inequality indicating that thecircumradius of the simplex is not less than the n-fold inradius. Another inequality is derived to present the relationship betweenthe circumradius of the n-dimensional simplex and the circumradius and inradius of its pedal simplex. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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GUO Bao-feng Xiao Da-wei 《重庆大学学报(英文版)》2005,4(3):129-133
Using virtual reality for interactive design gives a designer an intuitive vision of a design and allows the designer to achieve a viable, optimal solution in a timely manner. The article discusses the process of making the Virtual Reality System of the Humble Administrator＇s Garden. Translating building data to the Virtual Reality Modeling Language （VRML） is by far unsatisfactory. This creates a challenge for computer designers to do optimization to meet requirements. Five different approaches to optimize models have been presented in this paper. The other methods are to optimize VRML and to reduce the file size. This is done by keeping polygon counts to a minimum and by applying such techniques as object culling and level-ofdetail switching. 相似文献