共查询到20条相似文献,搜索用时 125 毫秒
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低维ZnO纳米材料* 总被引:1,自引:0,他引:1
本文主要综述了近年来ZnO纳米材料制备领域的一些新方法,简单比较了各种方法之间的优缺点;讨论了制备不同形貌的ZnO纳米材料的影响因素,其中重点讨论了表面活性剂的作用;介绍了ZnO纳米材料的性质及其可能的应用领域;并对ZnO纳米材料的发展前景进行了展望。 相似文献
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基础化学实验室的建设与管理 总被引:2,自引:0,他引:2
化学实验室是全面完成化学教学任务的重要基地。 我院2002年建立了设备比较先进的化学实验室,给学生创造了良好的实验条件,并进行了科学化的管理,规定了各种规章制度和有关职责,较好地完成了化学教学任务。在实践中。采取:固定优秀代课教师兼管,勤工助学学生帮忙的管理办法,既减轻教师的劳动强度,又培养了学生的技能,且协调了各种关系,有利于化学教学质量的提高。 相似文献
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以往的研究理论和矿场实验已经证明,蒸汽泡沫驱是一种有效防止汽窜、提高稠油采收率的方式。本文分析了蒸汽泡沫驱目前所存在的问题,提出了解决办法;回顾了耐温耐盐发泡剂的研究历程,给出了发泡剂的一些合成方法,总结了前人制备高温耐盐发泡剂、复配泡沫体系的研究成果,指出了现有发泡剂的不足;探讨了泡沫产生、流动和稳定机理,从微观方面进一步探寻稳定泡沫的原理;初步介绍了纳米颗粒提高泡沫稳定性的原因,结合泡沫产生和流动的微观机理,分析了纳米颗粒提高蒸汽泡沫驱油效率的实质。最后,展望了蒸汽泡沫驱未来的发展方向。 相似文献
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通过日常观察和问卷调查,发现浙江省高中生普遍存在对化学的误解,从高中化学课程及考纲的内容探讨了其成因,同时列举了若干与教学相关的事实,并给出了对考纲的建议;列举了多个有机试题命题不严谨和一线教师课堂讲述不严谨的案例,反思了其原因和后果,随后给出了相关建议。 相似文献
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通过对比不同的前处理措施,建立准确、快速测定胶囊中铬(Cr)的方法。分别采用微波消解和电热恒温自动消解法进行前处理,石墨炉原子吸收法进行测定。试验表明:该方法在0~40.0μg/L范围内呈线性相关,相关系数为0.997 7,检出限为0.017 mg/kg,样品的加标回收率在90%~110%之间。对标准物质圆白菜中铬的测定在所要求的准确度范围之内。同时作了原子吸收光谱仪和电感耦合等离子体(ICP)发射光谱仪两种仪器的对照试验,方法的稳定性良好。采用微波消解或电热恒温消解作为胶囊的前处理,通过原子吸收法或ICP法均能准确测定胶囊中的铬。 相似文献
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Tyler Cassidy Philippe Gaudreau Hassan Safouhi 《Journal of mathematical chemistry》2018,56(2):477-492
In this work, we propose a method combining the Sinc collocation method with the double exponential transformation for computing the eigenvalues of the anharmonic Coulombic potential. We introduce a scaling factor that improves the convergence speed and the stability of the method. Further, we apply this method to Coulombic potentials leading to a highly efficient and accurate computation of the eigenvalues. 相似文献
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Yanting Tian Zhe Lü Mingliang Liu Xingbao Zhu Bo Wei Yaohui Zhang Xiqiang Huang Wenhui Su 《Journal of Solid State Electrochemistry》2013,17(1):269-275
The effect of gas supply method on the performance of a single-chamber solid oxide fuel cell micro-stack and single cells was studied, and a novel gas supply method with separated gas vents in the gas tube was proposed. The traditional gas supply method was also investigated for comparison. Results showed that the single cells could obtain a uniform open-circuit voltage and power output by using the separated gas supply method. For the traditional gas supply method, the cell at the outlet position yielded inferior performance compared to that of the inlet cell. The gas flow rate showed a significant effect on the performance of the cells. Finally, the stack operated with the separated gas supply method produced a higher power output than that operated with the traditional gas supply method. 相似文献
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蔗糖酯的合成研究进展 总被引:2,自引:0,他引:2
综述了蔗糖酯的合成方法及工艺的研究进展,并对其反应机理进行了阐述.蔗糖酯的合成方法主要有四种:溶剂法、微乳化法、无溶剂法以及酶催化法.溶剂法采用DMF或DMSO为溶剂,但是这两种溶剂均有毒,限制了蔗糖酯在食品等行业的应用.微乳化法采用丙二醇或水代替溶剂法所使用的有毒溶剂,并加入乳化剂,使反应体系近似为均相体系.无溶剂法则是通过在反应体系中加入乳化剂或表面活性剂等使熔融相成均一相,反应平稳.但是一般无溶剂法反应温度较高,反应不易进行,产率低,且产品质量得不到保证.酶催化合成法是一种新的生物合成方法,采用生物酶代替传统的催化剂合成蔗糖酯,该法催化活性高、反应条件温和、选择性强、产物易分离等优点.文中还对蔗糖酯粗品的纯化工艺进行了介绍. 相似文献
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Aliaksei A. Strechan Gennady J. Kabo Yauheni U. Paulechka 《Fluid Phase Equilibria》2006,250(1-2):125-130
Correlation relations based on Stefan's rule, which defined dependence between the enthalpy of vaporization, the surface tension, the molar volume and the molar mass of a substance, were obtained. For development of the correlation equations two computational procedures were used: a method of the least squares and a method of artificial neural networks. The method of artificial neural networks was shown to give somewhat better results than the linear least-squares procedure. The average deviation of the calculated values from the experimental ones did not exceed 6% for training set of substances and 10% for control set (the method of the least squares). For the method of artificial neural networks it is 3% and 8%, respectively. 相似文献
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Ruben Ruiz-Femenia Jose A. Caballero 《Journal of Thermal Analysis and Calorimetry》2012,107(2):585-596
The non-parametric kinetic method (NPK) is a method for the processing of thermoanalytical data, which does not make any assumption
about the functionality of the reaction rate with the degree of conversion or with the temperature. This method has not been
widely used due to its mathematical sophistication and difficulty of automation. The original NPK method uses only the first
(maximum) singular value whereas additional information could be drawn from the remaining singular values. A hypothetical
application of the NPK, which uses all the significant singular values (modified version of the NPK), is the separation of
two or more steps of a complex decomposition reaction. Using simulated data, we have demonstrated that the modified version
of the NPK is not useful to discriminate among the decomposition steps of a consecutive complex decomposition reaction scheme.
Nevertheless, the analysis of the relative strength of the singular values is useful to assess the degree of separability
of the temperature and conversion functions, which are the outcome of the NPK. Taking into account the relative magnitude
of the first singular value with regard to the remaining singular values, we have proposed an automated two-scan version of
the NPK method which guarantees two separable functions. As the separability of both temperature and conversion functions
is the imperative assumption of the single-step kinetics approximation, the two-scan NPK method can be used as a testing method
for those methods based on this approximation, the model-free and model-fitting methods. 相似文献
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利用气相色谱(GC)技术,采用酸水解提取脂质,比较了6种甲酯化法(乙酰氯-甲醇法、H2SO4-甲醇法、HCl-甲醇法、KOH-甲醇法、KOH-甲醇+H2SO4-甲醇法和KOH-甲醇+HCl-甲醇法)对脂肪酸测定的影响,优选牦牛骨中脂肪酸测定的最佳方法。37种脂肪酸标准样品在0.28~250.00 mg/L范围内线性关系良好,相关系数均大于0.99(除C4:0外)。碱酯化法和酸碱结合法几乎无法测出牦牛骨中的脂肪酸,其测得的总脂肪酸含量小于0.20 g/100 g。乙酰氯-甲醇法测得的总脂肪酸含量(13.61 g/100 g)显著高于H2SO4-甲醇法(总脂肪酸含量为11.68 g/100 g)和HCl-甲醇法(总脂肪酸含量为3.18 g/100 g)测得的结果。乙酰氯-甲醇法和H2SO4-甲醇法的日内和日间精密度分别为0.27%~8.60%和0.34%~2.64%,两种方法中脂肪酸的回收率为83.06%~105.54%。结果表明,酸水解-乙酰氯-甲醇法是牦牛骨中脂肪酸测定的最佳方法。C18:1n9c、C16:0、C18:0和共轭亚油酸(CLA)是牦牛骨的主要脂肪酸,其总和达脂肪酸总量的85%以上,饱和脂肪酸与不饱和脂肪酸含量比值约为1:2。牦牛骨中脂肪酸的研究为骨资源脂质的有效利用提供了重要依据。 相似文献
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提出反应类等键方法并用于高温燃烧机理中一类重要反应——烷基自由基β位裂解反应的反应势垒和速率常数的精确校正计算. 通过10种不同从头算水平对类反应中5个代表反应的反应势垒的计算发现, 用反应类等键反应方法和直接从头算方法获得的5 个代表反应的反应势垒最大绝对偏差的平均值分别为5.32 和16.16 kJ·mol-1, 表明反应类等键反应方法计算的反应势垒对不同水平从头算方法的依赖性小, 可在较低从头算水平计算得到精确的反应势垒, 解决大分子体系反应势垒的精确计算问题. 此外应用反应类等键反应方法在BHandHLYP/cc-pVDZ 从头算水平计算了3 个代表反应的速率常数, 并与文献报道的实验值进行了比较, 其在500-2000 K温度区间内计算速率常数与实验速率常数中较大值与较小值的比值kmax/kmin的平均值为1.67, 最大值也仅有2.49. 表明应用反应类等键反应方法在较低从头算水平即可对同类反应的速率常数进行精确计算.最后在BHandHLYP/cc-pVDZ从头算水平用反应类等键反应方法计算了13个烷基自由基β位裂解反应的速率常数. 相似文献