共查询到20条相似文献,搜索用时 982 毫秒
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提出了“互联网+”背景下,“无机及分析化学”课程教学“一核心、二目标、三探索、四构建”的教学策略。实施结果表明,基于学生发展的课程核心知识,以“具有解决复杂制药工程、化工工程、材料工程的化学基础知识”“为学习后续课程打下坚实基础”2个具体教学目标为导向,通过开展综合实践活动、案例教学、课程思政等3种教学改革探索,构建线上线下有机衔接的立方书、立体化线上教学资源、线上线下混合型教学模式及过程和结果相融合的SPOC教学模式下的课程评价体系4种教学举措,能有效提高课程教学质量。 相似文献
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为解决无机与分析化学课程教学过程中面临的诸多现实问题,实现德育引领、能力培养、知识传授的教育教学目标,以学生的学习需求、学习能力、学习成效为中心,在线上与线下混合式教学的基础上,基于微课和翻转课堂,构建了“线上、线下、理论、实践、思政”有机融合的“五位一体”混合式教学新模式,对该教学模式的研究涵盖教学目标、教学内容、教学活动及学习效果评估等4个方面。经过2个学期的教学实践,结果表明,该教学模式提高了学生的学习主动性,收到了良好的学习效果。 相似文献
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为建设适应新时代要求,突出高阶性、创新性、挑战度的一流本科课程,实现价值引领、能力培养和知识传授的教育教学目标,结合功能材料专业的特点和民族高等院校学生的学情,构建了物理化学基础课程的“四模块、三阶段、两时空、双平台”的混合式教学新模式,重塑了“价值引领模块、基础理论模块、多学科融合模块和虚拟仿真实验模块”的“四模块”内容体系。通过“四模块”嵌入下的混合式教学实践研究,结合学生的课前、课中、课后等学习成绩,多维度评价学习效果,并藉由调查问卷来分析学生对混合式教学的评价,最终研究结果表明学生的个性化自主学习能力有了显著提高、学生运用物理化学理论解决复杂问题的综合能力得到了提升,学生经过刻苦学习获得了素质提高的成就感。 相似文献
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Charles H. Langley Diwakar M. Pawar Eric A. Noe 《Journal of Molecular Structure》2005,732(1-3):99-111
The optimized geometries, relative free energies and related thermodynamic properties, harmonic frequencies, and dipole moments have been calculated at the HF and MP2 levels for ethynyl formate (1a), ethynyl acetate (1b), cyano formate, HCO2CN (1c), cyano acetate (1d), S-ethynyl thioformate (2a), S-ethynyl thioacetate (2b), S-cyano thioformate (2c), S-cyano thioacetate (2d), N-ethynylformamide (3a), N-ethynylacetamide (3b), N-cyanoformamide (3c), and N-cyanoacetamide (3d) with the gaussian 98 program. For ethynyl formate, the calculation for 25 °C at the MP2/6-311++G(df,pd) level predicts that the Z isomer is more stable by 1.23 kcal/mol. For S-ethynyl thioformate, calculations at the MP2/6-311++G(2d,2p) level predict that the E isomer is favored by 0.71 kcal/mol at 25 °C. The E isomers of N-ethynylformamide and N-ethynylacetamide were found at all levels to be more stable than the Z isomers at 25 °C. For cyano formate and cyano acetate, calculations at the MP2/6-311++G(df,pd) level predict that the Z isomers are more stable at 25 °C by 1.50 and 2.72 kcal/mol, respectively. At this level and temperature, the Z isomers of 2c, 2d, 3c, and 3d are predicted to have free energies of 0.46, −0.07, 1.22, and 2.28 kcal/mol, respectively, relative to the E conformations. Z to E free-energy barriers at 25 °C of 8.63, 10.64, 17.63, 7.39, and 14.03 kcal/mol were calculated for 1a, 2a, 3a, 1c, and 3c at the HF/6-311G(d,p) level, and at the HF/6-311+G(d,p) level, the free-energy barrier for 2c was 7.08 kcal/mol. 相似文献
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黎志明 《广东微量元素科学》2010,17(7):49-70
从心脑血管疾病的流行率、心脑血管疾病的元素病因、心脑血管疾病的元素诊断和心脑血管疾病的元素治疗等4个方面讨论了元素医学防治心脑血管疾病的临床意义。 相似文献
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Iwona A. Rutkowska Anna Wadas Ewelina Szaniawska Anna Chmielnicka Agnieszka Zlotorowicz Pawel J. Kulesza 《Current Opinion in Electrochemistry》2020
Copper- and copper oxide–based materials are, in principle, promising components (supports, reactive sites, and visible light–absorbing semiconductors) of electrocatalysts and photocathodes for reduction of carbon dioxide. Electrochemical and photoelectrochemical approaches are generally suitable for the low-temperature CO2-conversion to carbon-based simple organic fuels or utility chemicals.Different concepts of utilization, including nanostructuring, doping, admixing, preconditioning, modification, or functionalization of various copper- and copper oxide–based systems for catalytic electroreduction and photoelectrochemical reduction of CO2 are elucidated, as well as important strategies to enhance the systems' overall activity and stability are discussed. 相似文献
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The high-resolution (1)H, (13)C, (1)H-(1)H COSY and (1)H-(13)C COSY NMR spectra have been recorded in CDCl(3) for arylacetonitriles 1-12 and analyzed. The arylacetonitriles 3-7 exist in two isomeric forms E (methyl group is anti to cyano group) and Z (the methyl group is syn to cyano group) in solution. Normal chair conformation with equatorial orientations of phenyl rings at C-2 and C-6 for monocyclic nitriles 1 and 2, epimeric chair structure EC (axial configuration of methyl group at C-3) for both the E and Z isomers of arylacetonitrile derivatives (3-7) and a distorted boat form, B(3), for the N-acylacetonitrile derivatives (8-10) have been proposed based on NMR data. The bicyclic nitriles 11 and 12 exist in twin chair conformations in solution. DFT calculations and chemical shifts also support these conformations. Geometry optimizations for 1-12 were carried out according to density functional theory using B3LYP/6-31G(d,p) basis set and for 1 and 8 the theoretical geometrical parameters have been compared with those of single crystal measurements. 相似文献
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M. G. Voronkov O. M. Trofimova Yu. I. Bolgova L. V. Klyba L. I. Larina A. I. Albanov V. A. Pestunovich N. F. Chernov K. B. Petrushenko 《Chemistry of Heterocyclic Compounds》2003,39(12):1639-1644
We have synthesized 1- and 2-(trimethylsilylmethyl)- and 1- and 2-(trimethoxysilylmethyl)benzotriazoles by reaction of 1,2,3-benzotriazolylsodium with trimethyl- or trimethoxy(chloromethyl)silane. We obtained 1- and 2-(silatranylmethyl)benzotriazoles by transesterification of the latter with triethanolamine. 相似文献
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C. K. Kim M. Aguilar-vega D. R. Paul 《Journal of Polymer Science.Polymer Physics》1992,30(10):1131-1142
Dynamic mechanical and gas transport properties for homogeneous homopolymer blends and random copolymers of bisphenol-A and tetramethyl bisphenol-A polycarbonates (PC-TMPC) were determined. The gas transport measurements were performed at 35°C for the gases He, H2, O2, Ar, N2, CH4, and CO2. The results show that the copolymers have lower permeability, apparent diffusion, and solubility coefficients than the blends. Permeability coefficients for blends follow a semilogarithmic ideal mixing rule while copolymers exhibit negative deviations from this. Specific volume measurements show that the free volume available for gas transport is slightly larger in copolymers than in blends of the same composition. These apparently contradictory results may relate to the differences in local mode chain motions observed for the copolymer and blend series. The γ relaxation processes in PC and TMPC seem to operate independently in the blends (no intermolecular coupling) while there is clear evidence for intramolecular coupling in the copolymers. © 1992 John Wiley & Sons, Inc. 相似文献
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Manfred Spiekermann Daniel Bougeard Hans -Joachim Oelichmann Bernhard Schrader 《Theoretical chemistry accounts》1980,54(4):301-313
The combination of normal coordinate analysis with intensity calculations gives quantitative information about molecular force fields and the assignments of vibrational frequencies. Calculations of vibrational intensities by means of a standard CNDO/2 version give rise to satisfactory results for the IR intensities. However, the calculated Raman intensities often differ strongly from the experimental data. Inclusion of 2p-polarization functions on hydrogen in the usually used valence basis set is quite successful to obtain improved molecular polarizabilities as well as Raman intensities. 相似文献
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V. D. Ignatiev 《Journal of Structural Chemistry》2005,46(4):744-751
A new system of atomic radii for the elements up to barium inclusive is constructed. Values of the radii are chosen so as the dependence between the dissociation energy of diatomic homonuclear molecules and a depth of atom overlapping is monotonous, and the scatter of data is minimal. The depth of overlapping is calculated as a difference between the sum of atomic radii and an experimental interatomic distance. Conclusions are made that: the radii of free atoms and ions are determined by the value of the electron density equal to 0.01 au; they considerably change in molecules and crystals only as a result of the charge transfer from cation to anion; covalent bonding is well described by the overlapping of free atoms (ions), confined by the surface of the given radius, and its energy depends upon the depth of overlapping of valence electron densities of atoms. A method of overlapping atoms is proposed for the approximate estimation of ionic sizes and charges in bound systems. 相似文献
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Ashraf A. Mohamed 《Monatshefte für Chemie / Chemical Monthly》2009,140(1):9-14
Abstract Two simple, sensitive, and selective spectrophotometric methods were developed for determining amodiaquine (AQ) and chloroquine
(CQ) based on their oxidation with potassium iodate and potassium bromate, respectively. The initial rates of oxidation of
AQ and CQ were monitored at 342 and 343 nm, the wavelengths of maximum absorptions of the two drugs. The various experimental
parameters affecting oxidation reactions were thoroughly studied and optimized. Beer’s law was obeyed for 0.2–4.0 and 0.5–5.0 μg cm−3, with correlation coefficients of 0.9999 and 0.9998 (n = 6) and a detection limit (based on the 3S
b
-criterion) of 0.04 and 0.06 μg cm−3 for AQ and CQ. The proposed methods were conveniently applied to determining AQ and CQ in pure and dosage forms.
Graphical abstract
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Di-, tetra-, and hexamethine merocyanines derived from malononitrile and heterocycles with moderate (dyes 1–6), strong (7–9), and weak (10 and 11) electron-releasing ability were synthesized. The electronic structures of merocyanines 10 and 11 are similar to the neutral polyene state, whereas those of 7–9 are similar to the ideal polymethine state. These tendencies become more pronounced with increasing length of the polymethine
chain. The merocyanines derived from heterocyclic residues with weak or moderate electron-releasing ability exhibit a positive
solvatochromism, whereas those with strong electron-releasing ability show a negative solvatochromism. An increase in the
polarity of the solvent makes the former compounds more similar to polymethines, whereas the latter become more similar to
polyenes bearing opposite charges on the end groups. The nature of the factors (nonspecific solvation, specific nucleophilic
and electrophilic solvation, and vibronic interactions) responsible for the observed characteristic features was analyzed.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2726–2735, December, 2005. 相似文献