共查询到20条相似文献,搜索用时 156 毫秒
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论文对我国少数民族畲族学生进行了化学学习中非智力因素影响的调查与分析,从基本情况、化学学习动机、化学学习兴趣、化学学习习惯、化学学习意志等5个方面作了调查,对其特征和问题作了分析,提出了促进畲族学生化学学习发展的教学建议。 相似文献
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科学阅读是科学学习的重要组成部分,将科学阅读策略应用于化学学习中,有利于学生对化学概念和化学知识的理解,有利于学生将新知识、新概念整合到自己的认知结构中,从而达到有意义的学习。 相似文献
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元素符号是学习化学的重要工具,是化学启蒙教育阶段的基础内容。在教学过程中如果采用死记硬背的方法,不仅加重了学生学业负担,而且严重影响学生学习化学的兴趣。利用巧妙的教学方法,既可以让学生轻松学化学,又能够培养学生的化学情感,对做好化学启蒙教育工作具有重要价值。 相似文献
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结合具体教学实例,阐述了如何利用化学实验课堂中“异常状况”的发生,抓住教学契机,顺“势”而为。通过创设真实且富有价值的问题情境,进一步激发学生学习兴趣,通过师生互动,创造“灵活动态”的化学课堂。在具体教学策略实施分析的案例中,预设课堂可能的“异常状况”,通过“实验探究”,提高学生对复杂情境的认知能力;面对课堂偶发的“异常状况”,通过“多角度辨析”,增强学生对复杂体系的分析能力;基于课堂典型的“异常状况”,通过“进阶式实验探究”,提升学生对复杂问题的处置能力。对“异常状况”处理的过程中,注重化学知识结构化,认识思路结构化,关注学生的认知发展规律,注重情境、活动和问题解决的整体设计,突出学生学习方式的转变,促进学生化学学科核心素养的形成和发展。 相似文献
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教材中演示实验或探究实验是针对某一个实验原理引导学生学习化学知识与实验操作技能、验证化学原理、训练科学思维.理论指导实践的化学实验教学模式旨在引导学生用学习过的化学知识和化学实验技能对未知领域进行综合性探索,学习新知,培养创新能力. 相似文献
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初三化学是中学生学习化学的开端.??教师要引导学生爱好化学,学好化学,可以通过多种途径.现就对学生进行学习目的教育和辩证唯物主义观点教育,谈点看法. 一、明确教学目的,结合实际对学生进行学习目的教育. 为了使学生学习化学有个良好的开端,必须让他们明确学习化学的目的和重要性,这一点非常重要. 在化学的第一堂课——绪言上,就要使学生清楚地知道:世界是物质的,化学研究的对象就是物质.所以,化学研究的范围是非常广泛的,化学与各门科学、工农业生产、国防建设和 相似文献
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自主学习是一种学生主动参与的、建构性的学习过程.自主学习能力是由内在学习动机、认知策略与元认知监控3个要素构成的.依据自主学习能力的构成及化学学科的特点,我们通过自编问卷测查化学新课程教学中学生自主学习能力的现状.结果显示,目前中学化学教学中学生自主学习能力水平较高,但随着年级的升高,学生的化学自主学习能力水平却呈现出显著降低的趋势. 相似文献
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Subhasish Purkayastha Clair J. Cheer Raymond P. Panzica 《Journal of heterocyclic chemistry》1990,27(3):753-757
The involvement of the 5′-hydroxyl group on β-D-arabinofurano[1′,2′:4,5]oxazolo-s-triazin-4-one-6-thione ( 1b ), to form an intramolecular covalent adduct at C6, is postulated to explain the formation of almost equal amounts of 5-N-alkyl-β-D-arabinofurano[1′,2′:4,5]oxazolo-s-triazin-4-one-6-thione and 5-N-alkyl-β-D-arabinofurano[1′,2′:4,5]oxazolo-s-triazine-4,6-dione during alkylation of 1b . An X-ray crystallographic study was conducted on 5-N-methyl-β-D-arabinofurano[1′,2′:4,5]oxazolo-s-triazine-4,6-dione ( 2a ) and its solid state structure was established. This was compared to the energy minimized structure of the same compound that was generated by the molecular modeling program, MACROMODEL. Force field calculations (Allinger's MM2) on this structure and other intermediates lend support to the concept of formation of the intramolecular covalent adduct. 相似文献
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Stanley L. Manatt 《Magnetic resonance in chemistry : MRC》1977,9(4):224-228
It has been found that LAOCOON III can fail to converge for some strongly coupled AA′BB′ spin systems unless trial coupling constants and chemical shifts within a few tenths of a Hz of the real parameters are used to initiate the iteration. This problem seemed linked to those spin systems possessing two or more pairs of energy levels which are nearly degenerate. In the cases where LAOCOON III failed, the program NMRENIT always yielded the correct, converged, iterative solution even with completely arbitrary starting parameters. The latter program also appears to accomplish a given number of iterations with an AA′BB′ system roughly three times as fast as the former program. 相似文献
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Mei Wang Chantal Septier Hlne Brignot Christophe Martin Francis Canon Gilles Feron 《Molecules (Basel, Switzerland)》2022,27(5)
Astringency is an important sensory characteristic of food and beverages containing polyphenols. However, astringency perception in elderly people has not been previously documented. The aim of the present work was to evaluate sensitivity to astringency as a function of age, salivary flow and protein amount. Fifty-four panellists, including 30 elderly people (age = 75 ± 4.2 years) and 24 young people (age = 29.4 ± 3.8 years), participated in this study. Astringency sensitivity was evaluated by the 2-alternative forced choice (2-AFC) procedure using tannic acid solutions. Whole saliva was collected for 5 min before and after the sensory tests. The results showed that the astringency threshold was significantly higher in the elderly group than the young group. No correlation was observed between the salivary protein amount and threshold value. However, a negative correlation between salivary flow and threshold was observed in the young group only. These results showed a difference in oral astringency perception as a function of age. This difference can be linked to salivary properties that differ as a function of age. 相似文献
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随着人们生活水平的不断提高,食品中痕量元素的含量越来越引起人们的关注.综述了近十年来催化动力学光度法在食品分析中对痕量元素进行测定的研究情况,并对催化动力学光度法在食品分析中的应用前景和研究方向进行了展望. 相似文献
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C. A. G. Haasnoot F. A. A. M. de Leeuw H. P. M. de Leeuw C. Altona 《Magnetic resonance in chemistry : MRC》1981,15(1):43-52
The relationship between vicinal NMR proton–proton coupling constants and the pseudorotational properties of the sugar ring in nucleosides and nucleotides is reinvestigated. Compared with our earlier study several important improvements are introduced: first, a new empirical generalization of the classical Karplus equation is utilized, which allows an accurate correction for the effects of electronegativity and orientation of substituents on 3J(HH); second, empirical correlations between the parameters governing the conformation of β-D -furanosides (taken from an analysis of 178 crystal structures) were used to define proton–proton torsion angles as a function of the pseudorotation parameters P and Φm; and, third an iterative least-squares computer program was devised to obtain the best fit of the conformational parameters to the experimental coupling constants. NMR data for the sugar ring in the following compounds were taken from the literature and analysed: 3′,5′-cyclic nucleotides, a base-stacked ribonucleotide, 2′-anhydroarabinonucleosides, α-D -2′,2-O-cyclouridine, 2′- and 3′-aminosubstituted ribonucleosides, 2′- and 3′-deoxyribonucleosides. The present results confirm that the conformational properties found in the solid state are, on the whole, preserved in solution. 相似文献
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G. V. Lisichkin 《Russian Journal of General Chemistry》2013,83(6):1257-1265
Experimental results indicating the existence of special abilities in chemistry were reported, with chemistry interpreted as the science about substances and their transformations in accordance with the classical definition. It was shown that the key component of abilities in chemistry is a learner’s particular attitude to a substance. The possibilities of diagnosing schoolchildren’s abilities in chemistry were discussed. Promising directions for further psychological and educational research concerning the abilities in chemistry were considered. 相似文献
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From analysis and refinement by the LAOCOON III program of the 220 MHz 1H spectrum of 2,2′-biquinoline, recorded as a saturated solution in carbon disulphide, most derived chemical shifts and coupling constants are close to corresponding values in quinoline. However, H-3 is at 1.5 ppm lower field in 2,2′-biquinoline than in quinoline and the ortho-coupling 3J(34) in the heterocyclic ring is 0.5 Hz larger in 2,2′-biquinoline than in quinoline; fairly free rotation about the 2,2′ bond is inferred. 相似文献
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开孔泡沫塑料率相关的拉伸力学性能及本构关系 总被引:6,自引:0,他引:6
以Lederman的工作为基础,通过假设基体材料服从Voigt体描述的粘弹性本构关系,导出了开孔泡沫塑料受拉伸的率相关本构关系;在此基础上研究了泡沫塑料力学性质同应变、应变率和结构参数的关系. 相似文献
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Vernon L. Bell Philip R. Young 《Journal of polymer science. Part A, Polymer chemistry》1986,24(10):2647-2655
A study was conducted of the effects of meta-para isomerism on the synthesis and properties of aromatic bismaleimides and polyaspartimides. Three isomers, 3,3′-, 3,4′-, and 4,4′-diaminodiphenylmethanes (methylenedianilines), were used to prepare three isomeric bismaleimides. The bismaleimides then were reacted with their respective isomeric diamines in m-cresol solution to give a series of isomeric polyaspartimides. The properties of each of the isomeric series were measured and compared. Strong flexible films were solvent cast from the two polyaspartimides derived from the 3,4′- and 4,4′-diamines and their respective bismaleimides. Tensile properties of the films from the 3,4′-diamine/3,4′-bismaleimide combination polyaspartimide were equivalent to those from the 4,4′-diamine-derived polymer. That finding, together with that polymer's lower softening temperature and the nonmutagenic nature of the 3,4′-diamine monomer, suggested a potential usefulness for 3,4′-diaminodiphenylmethane as a replacement for 4,4′-diaminodiphenylmethane in addition polyimides. 相似文献