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基于认识方式有关理论及高中生化学平衡认识模型,分析高中生在化学平衡从必修到选修的认识发展情况,进行促进学生认识发展的教学设计,实施课堂教学,并对比传统以知识获得为主的课堂教学,通过学生实际认识测查数据说明促进学生认识发展型教学优于传统教学。建议教师充分挖掘化学平衡常数的认识功能与价值,围绕化学平衡常数开展课堂教学,建立和发展学生对化学平衡的认识。 相似文献
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以高中生有机物性质认识能力的构成为指导,基于对不同版本教材为学生认识有机物性质所搭建的先行组织者的内容与功能的分析,基于对北京市丰台区学生情况的分析,阐述了为促进学生有机物性质认识能力发展,建构认识域及认识角度和思路的策略及方法。 相似文献
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基于无机元素化合物知识结构特点、中学化学课程的教学要求以及学生认识和解决元素化合物有关问题的思维机制,提出元素化合物认识模型,运用认识对象、化学问题、能力任务、认识角度和认识方式类型等重要的认识变量,揭示了中学生针对无机元素化合物性质这一认识域的认识系统构成。研究还基于模型进行了《化学1》中金属元素及其化合物单元复习教学实践,结果表明基于模型进行复习教学的整体设计和实施有利于学生能力的发展。在此基础上进一步提出了基于元素化合物认识模型进行复习教学的有效策略。 相似文献
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对已有的认识方式4要素的关系进行了修正,在分析了学生已有的物质结构基础知识和已有认识方式的基础上,阐述了“微观结构与物质的多样性”对学生认识方式可能产生的影响。分析了如何通过单元教学设计来实现这种影响,促进学生认识方式的发展,并给出了教学设计案例。 相似文献
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有机化学是药学专业非常重要又较难学习的一门专业基础课,认识有机化合物的结构是学好这门课程的基础,单纯平面教学无法深入地将分子的实际空间结构充分展示。通过在有机化学教学中引入球棍模型及ChemBioOffice软件,可以帮助学生迅速地理解、掌握有机化合物的立体结构,为后续的教学内容打下良好的基础。 相似文献
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Several models have been proposed to describe the carbon number product distribution and mechanism in Fischer-Tropsch synthesis (FTS). However, these models have not fully explained the product distribution and mechanism owing to the wide range and complexity of hydrocarbons in FTS. This study was conducted based on the Yao and Anderson-Schulz-Flory (ASF) carbon number product distribution models for light (C1–C6) hydrocarbon products of a Fe/Al2O3 catalyst. The product distribution based on the molar ratio of olefin to paraffin (O/P) and the neighboring olefins was also studied in order to better understand the mechanism in FTS and C2 olefin deviation during FTS.Two sets of experiments (A and B) with different reaction conditions were conducted in microtubular fixed-bed reactors on the Fe/Al2O3 catalyst for 2249 h and 360 h, respectively. We found that the α values from the Yao and ASF carbon number product distribution models are relatively similar. The α values from the Yao carbon number product distribution plots are relatively constant, irrespective of the reaction conditions.Interestingly, it was also found that the secondary reactions of the C2 olefin by re-adsorption to produce paraffins and long-chain olefins are dependent on the CO conversion and the reaction temperature during the FTS. Also, the product distribution of the neighboring olefins during the reduction condition gave a similar trend to what was observed for other reaction conditions. This result confirmed what was observed in the Yao and ASF carbon number product distribution of the olefins. 相似文献
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Rejean Landry Alexander Penlidis Thomas A. Duever 《Journal of polymer science. Part A, Polymer chemistry》2000,38(13):2319-2332
We investigate the effect of the presence of reactive impurities during copolymerization on mathematical model discrimination and determine if impurities adversely affect the model discrimination process, depending on the criteria and response(s) used. Nonlinear mechanistic process models are employed in a multiresponse statistical discrimination scenario. The investigation also considers, via several case studies, the extremely interesting question of whether impurity effects could lead to incorrect choices about the copolymerization mechanism itself (terminal versus penultimate model). The answers to the above questions are that reactive impurities do affect the model discrimination process and, what is more, they may mislead researchers as to the choice of the copolymerization mechanism. The latter unexpected result is further illustrated with experimental data from the literature. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2319–2332, 2000 相似文献
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Bharati Bhattacharyya Chitrani Medhi B. R. De S. P. Bhattacharyya 《Journal of Chemical Sciences》1989,101(3):235-242
An MCSCF model including the effects of solvent polarization is developed. The model is applied within the limitations of
INDO approximations to look into the dominant effects of solvent polarization on the electronic structure in the excited states
of a model system (e.g.nπ
* states of H2CO). Important features of macroscopic solvation-induced reorganization of electron density and some consequence thereof are
noted. 相似文献
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Russian Journal of Electrochemistry - A method for determination of parameters of a three-wire model and Lichtenecker model on the basis of experimental data of conductivity measurement for... 相似文献
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Abstract The log-log relationship between the bioconcentration tendency of organic chemicals in fish and the n?octanol/water partition coefficients breaks down for very hydrophobic compounds. The use of parabolic and bilinear models allows this problem to be overcome. The QSAR equation log BCF = 0.910 log P - 1.975 log (6.8 10?7 P + 1) - 0.786 (n = 154; r = 0.950; s = 0.347; F = 463.51) was found to be a good predictor of bioconcentration in fish. 相似文献
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The solubilities of genistin in pure solvents including tetrahydrofuran, acetone, ethyl acetate, acetonitrile, isopropanol, n-butyl alcohol, methanol, cyclohexane, n-hexane, chloroform and ethanol were determined by the high performance liquid chromatography (HPLC) analysis method at T = (283.2, 293.2, 303.2, 313.2 and 323.2) K. The fusion enthalpy of genistin was estimated by the group contribution method. The solubility data of genistin were correlated by the simplified thermodynamic model, the modified Apelblat model, λh model and NRTL (Non-Random Two-Liquid) model. The calculated values by all models were in good agreement with the experimental values and however, the NRTL model could give better correlation results than other three models. 相似文献
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高分子黏弹性的经典唯象模型 总被引:2,自引:0,他引:2
高分子流体的黏弹性质是高分子科学和工程中一个非常重要的研究领域.与简单黏性液体和弹性固体不同,外场作用下缠结高分子流体呈现出复杂的黏弹性行为,例如应力不仅仅与应变幅度或应变速率有关,还与整个形变历史相关.近半个世纪以来,人们建立了很多描述这些复杂黏弹性质的模型和理论,其中一类是基于连续性介质力学原理的唯象模型,例如:Maxwell模型、Voigt-Kelvin模型和在时空上所有参数为常量的连续性模型;另一类是瞬态网络模型,该模型把缠结点考虑成瞬态交联点,高分子链看成珠簧链;还有一类是微观分子理论,其中最著名的是"管子模型".本文首先介绍缠结高分子流体的线性黏弹性响应和Boltzmann叠加原理的基本概念,然后,重点综述描述高分子黏弹性质仍非常有实际应用价值的3个经典唯象模型,包括Maxwell模型、Voigt-Kelvin模型和瞬态网络模型,特别是这些理论的详细推导和存在的主要问题.关于高分子黏弹性的微观理论将在其它综述中单独介绍. 相似文献
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Simplistic modeling approach to heterogeneous dilute-acid hydrolysis of cellulose microcrystallites 总被引:9,自引:0,他引:9
Pär O. Pettersson Robert W. Torget Robert Eklund Qian Xiang Y. Y. Lee Guido Zacchi 《Applied biochemistry and biotechnology》2003,106(1-3):451-455
The classic kinetic model for cellulose hydrolysis is often referred to as pseudo-homogeneous, a term revealing the insight that the process is actually heterogeneous. During the past 10–15 yr, the shortcomings of this
model have been demonstrated in various studies and the interest in the heterogeneous aspects has increased. The present work
presents a simplistic model in which the intrinsic, heterogeneous hydrolysis and transport rates are coupled by the assumption
of a constant glucosidic surface concentration. The mechanisms affecting these two rates are largely unknown, but the model
serves as a guideline for further exploration of the process. 相似文献
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Maxim P. Evstigneev Anatoly S. Buchelnikov Viktor V. Kostjukov Irina S. Pashkova Vladyslav P. Evstigneev 《Supramolecular chemistry》2013,25(4):199-203
Numerous applications dealing with molecular aggregation at the interface of biology, physics and chemistry use either the dimer or the indefinite equilibrium constant models even though there is the well-known property of indistinguishability of the models with respect to fitting experimental data by various experimental techniques. The problem of indistinguishability is uncovered in the present work and the way in which the existing paradigm of how these models should be applied to analysis of molecular self-association is suggested. 相似文献