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为了获得氢氟醚HFE7100、HFE7500的热物理性质参数,补充现有数据不足,为其作为电子元器件的冷却介质、工业清洗剂等工程应用提供技术支持,利用瞬态热线法测量了常压下HFE7100和HFE7500的热导率,并用表面光散射法测量了HFE7100和HFE7500的液相黏度和表面张力。HFE7100和HFE7500的热导率和液相黏度均关联成温度的多项式函数,HFE7100热导率和黏度的实验值和关联式的平均绝对偏差分别为0.37%和1.19%,HFE7500热导率和黏度的实验值和关联式的平均绝对偏差分别0.08%和1.10%。利用改进的van der Waals关联表面张力和温度的关系,HFE7100和HFE7500的表面张力的实验值和关联式的平均绝对偏差分别为0.03 mN·m-1和0.02 mN·m-1。获得的HFE7100和HFE7500的热导率、黏度和表面张力实验数据及方程,可为其工程应用提出数据支持。 相似文献
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论述了二甲醚作为二次能源替代民用燃料和车用燃料的可行性和重大意义,阐述了我国能源短缺的危害和开发二次能源的必要性和紧迫性,简述了二甲醚的性质和制备,分析了二甲醚作为二次新能源开发的资源优势和对环境的重大意义及开发前景。 相似文献
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碳酸钙和淀粉对聚乙烯薄膜降解性能影响研究 总被引:1,自引:0,他引:1
目的:研究淀粉和CaCO3对塑料薄膜的降解影响。方法:将CaCO3填充膜和淀粉填充膜经自然曝露、紫外线照射和土埋处理,测试拉伸强度、断裂伸长率和分子量的变化。结果:自然曝露30d,CaCO3填充膜和淀粉填充薄膜的平均拉伸强度分别下降80.8%和54.4%,平均断裂伸长率分别下降99.4%和98.3%,分子量分别下降25.3%和13.8%;紫外光照120h,CaCO3填充薄膜和淀粉填充薄膜的平均拉伸强度分别下降14.7%和45.9%,断裂伸长率分别下降97.3%和97.0%,分子量分别下降66.7%和48.3%;土埋203d,CaCO3填充薄膜和淀粉填充薄膜的失重率分别为2.2%和15.0%。结论:CaCO3和淀粉均能加速聚乙烯塑料薄膜的降解,其中CaCO3的光降解性能方面优于淀粉,而淀粉的生物降解性能优于CaCO3。 相似文献
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大学有机化学教学改革创新 总被引:3,自引:0,他引:3
针对大学有机化学的特点和新世纪大学生培养要求,在坚持不懈的认真钻研、尝试和总结下,在和学生们教学相长的过程中,提出了大学有机化学教学改革创新的思路和方法,主要分为教学内容的整合和拓展、新型教学方法的引入和强化、学生综合能力的培养和训练以及科学发展观意识的形成和实践进行了详细的阐述。 相似文献
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粒度对煤粒燃烧和热解影响的理论分析 总被引:10,自引:2,他引:8
在化学热力学和动力学理论中引入表面项,并由此来分析和讨论粒度对煤颗粒燃烧和热解反应的影响规律.研究结果表明,煤颗粒的粒度对其燃烧和热解反应的热力学性质和动力学参数有明显的影响,粒度越小,影响越大;减小煤颗粒的粒径,化学反应的吉布斯函数差减小,煤颗粒燃烧和热解的趋势增大,使着火温度和热解温度降低,自燃容易发生;并且减小煤颗粒的粒径,其摩尔表面能增大,导致其燃烧和热解的表观活化能降低和速率常数增大,使煤颗粒的燃烧和热解速率加快,使转化率、燃尽度和热解度增加. 相似文献
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疟疾、登革热、黄热病、鼠疫、锥虫病和黑热病等媒介传播的疾病是引发全球人类和动物的发病和死亡的主要疾病。这些疾病对世界危害巨大,并对受害国家的社会经济发展产生深远的影响。因媒介传播疾病对经济和公众健康的重要性和潜在的流行性,其给人类、动物和植物健康带来了显著的威胁。蚊子是引起人类和动物疾病的病原体的最重要 相似文献
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由于许多饮用水的不安全性和易受污染导致饮用水供应仍旧是人类疾病和死亡的主要原因。需要作更大的努力解决饮用水供应影响是关键问题。需要努力评估和设定新的和更好的优先权用于饮用水的研究和实际应用。更多的利害关系则被包括在确认关键问题和设定安全饮用水优先权的过程中。 相似文献
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Carbon nanofibers (CNFs) are grown on metal catalysts and electrochemical treatment is used to remove the metal catalyst residuals from the as-grown CNFs. For comparison, the CNFs are also purified by a chemical method and a thermal method. The oxygen reduction reaction (ORR) properties of CNFs purified by these three methods are examined by cyclic voltammetry. CNFs treated by the electrochemical method have a more positive ORR onset reduction potential and peak potential compared with those treated by chemical and thermal methods, and this is because the microstructures of CNFs are less changed by electrochemical method. However, they have a lower electrochemical capacity and ORR peak current than those treated by the chemical method. Cyclic voltammetric measurements at different scan rates confirm that the oxygen reductions on CNFs treated by electrochemical and chemical methods are controlled by diffusion, while on CNFs treated by thermal method is partially influenced by diffusion. 相似文献
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The present work is dealing with the attachment of d-glucosaminic acid (D-GA) on glassy carbon electrode by two different methods. Firstly, the electrode was modified by chloromethylphenyl groups by reduction of 4-chloromethylphenyldiazonium cations followed by the nucleophilic substitution of the chlorine by the amine functionality of D-GA and secondly by the direct immobilization of the amine terminated molecule. The generality of the nucleophilic substitution reaction and the direct immobilization of an amine were also demonstrated with reactants bearing an electroactive ferrocene moiety; 4-nitrophenylferrocene (NFc) and 4-ferrocenylaniline (FcA). The surfaces modified with FcA and NFc were investigated by cyclic voltammetry, and the D-GA modified electrodes were characterized by X-ray photoelectron spectroscopy. A preliminary evaluation of the efficiency of these surface modifiers to prevent protein adsorption was realized by scanning electron microscopy. 相似文献
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以季铵盐型改性淀粉为介孔模板,采用蒸汽相法成功合成多级孔EU-1沸石。通过XRD,FT-IR,SEM,N_2吸附-脱附和NH_3-TPD等手段对合成样品的物化性质进行表征。研究表明:通过调节季铵盐型改性淀粉的量,样品的介孔孔容增加了0.081 cm~3/g,外表面积增加了23.35 cm~2/g。通过二甲苯异构化测试来考察样品的催化性能,发现:对二甲苯(PX)平衡浓度提高了0.88个百分点,乙苯的转化率提高了8.47个百分点,C_8烃收率提高了1.66个百分点。 相似文献
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David A. Wood 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1984,34(4):232-240
The microbial processes occurring during mushroom cultivation are amenable to analysis by a number of experimental approaches. The microbial flora of the composting stage can be examined by microbiological and microscopical methods. The quantity of microbial biomass accumulating in the substrate can be measured by biochemical or microscopical techniques. Biodegradation of the substrate during composting or colonisation by mushroom mycelium can be assessed by chemical methods, assay of degradative enzymes and by following the degradation rate of radiolabelled plant polymers. Analysis of these processes indicates that substrate preparation (composting) is amenable to further control by manipulation of substrate environment and ingredients. Improvement in substrate utilisation might be achieved by strain selection, and further analysis of substrate composition. 相似文献
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改性活性炭吸附重金属镉的技术与机理 总被引:1,自引:0,他引:1
镉污染对饮用水安全造成了严重的威胁。活性炭吸附是水处理中最重要的处理方法之一,但是对镉等重金属的吸附较弱,通过改性可以改变活性炭的表面特性,从而促进对重金属的吸附。该文对活性炭进行了混酸氧化改性,臭氧氧化改性和乙二胺氨基化的改性,零电荷点和表面官能团大大发生变化,混酸改性后的零电荷点最低。通过吸附动力学的研究发现混酸改性的活性炭(Ac-0)对镉的吸附效果最好,且更加符合二级动力学的吸附模型。对AC-0活性炭进行了不同pH下吸附热力学的研究,结果表明吸附等温线用Freundlich的热力学模型拟合比较好,并且pH越大越有利于镉的吸附,pH对Ac-O吸附镉效果的影响试验也表明,由于零电荷点的影响,在pH小于9的情况下,随着pH的升高静电吸引力越强。 相似文献