共查询到20条相似文献,搜索用时 62 毫秒
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基于实证,设计了“氧化还原反应”高三复习课,以“污水处理”为主题,通过创设真实情境,激发生成问题,开展有效活动,引导学生在知识应用中加深对知识的理解,促进知识重构和认识转变,力求实现从虚拟走向真实,从学科走向学生,从经验走向科学,从教学走向教育。 相似文献
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上好“农村实用化学”课把教学、科研和服务结合起来孙绍仁(丹东师范专科学校化工系118003)为了适应农村经济发展和教育改革的需要,国家教委要求三年制的高等师范专科院校实行“主辅修”制,即用二年时间按二年制教学大纲学完主修课,剩下一年学习辅修课。化学专... 相似文献
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"起始课"和"结束课"一直没有受到应有的重视,尤其以"结束课"更为突出。通过对"起始课"和"结束课"内容特征的分析,重新审视"起始课"和"结束课"的教学目标和要求,为有效实施"起始课"和"结束课"的教学提供依据和参考。 相似文献
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简单分析了国内外微课发展概况,并从构建不同类型的微课和构建微课的实践与评价体系两方面入手,详细阐述了音频型微课、动画型微课及操作型微课的特点、在化工课程教学中的实施、评价方式及如何制作精彩的微课视频,为微课在高职化工课程教学作了大胆的探索。 相似文献
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在同课异构的教学实践中,分别通过新授课、概念课和复习课的教学设计和实施,阐述如何遵循认识发展来突破学生的认知障碍,通过教学设计、教学实施、教学评价和教学反思诠释“为什么教”“教什么”“怎么教”“教得怎么样”和“教学发展”的问题,凸显教学的本质。 相似文献
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Jacob Katriel 《International journal of quantum chemistry》1997,63(5):961-979
Progress in the formulation of a procedure for the combinatorial evaluation of the product of a single-cycle and an arbitrary class sum in the symmetric group algebra is presented. The procedure consists of a “global conjecture” concerning the representation of the product [(p)]n·[*]n in terms of a set of operators referred to as reduced class sums, and of an (incomplete) set of rules for the evaluation of the (n-independent!) coefficients of these operators. Two new types of index elimination rules are suggested, and some properties of the formalism are explored. These include useful sum rules as well as a certain “detailed balance” property that sheds some light on a combinatorial aspect of the global conjecture. The present results account for several new types of reduced class coefficients and suggest some feasible further developments. Some outstanding open problems are pointed out. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 961–979, 1997 相似文献
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五四新文学以来的青年形象解读有两种话语体系:青年话语和阶级话语。青年话语的前提是青年与老人之间的代际关系,强调青年的活力、勇敢与创新;阶级话语强调的是各个阶级共同体在经济和权力结构之中的不同位置。事实上,代际的生物关系时常通过社会关系起作用,阶级构成了社会关系的主要解释。五四新文学以来青年形象在阶级话语之中通常被定位为“小资产阶级”。20世纪50年代之后,青年话语与阶级话语的转换形成各种特殊的文学批评事件。80年代之后,青年话语与阶级话语各种比例的汇合构成复杂的、富有弹性的分析模式。消费社会的出现造就了中产阶级的青年形象。中产阶级与青年话语如何结合是未来的理论课题。 相似文献
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以上海市“空中课程”中高中化学X教师的线上课堂教学为例,采用SEC一致性分析模式,从核心素养的“证据推理与模型认知”这一视角,对其课堂提问与课程标准的一致性进行了分析。研究表明:(1)从总体上看,X教师的课堂提问与课程标准中的素养之间具有较好的一致性;(2)X教师的课堂提问在证据推理素养层面上与课程标准一致性程度欠佳,而在模型认知层面上与课程标准具有较好的一致性;X教师的课堂中根据具象证据或模型进行推理论证的问题多于课程标准中的素养要求,根据抽象证据进行推理论证的问题较少;(3)从素养水平维度分析,X教师课堂中低素养水平的问题占较大比例,高素养水平的问题少于课程标准要求;(4)上述偏差的产生主要受线上教学的影响,另外还受到考试要求、教师个人对课程标准的理解等因素的影响。 相似文献
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Ewig CS Berry R Dinur U Hill JR Hwang MJ Li H Liang C Maple J Peng Z Stockfisch TP Thacher TS Yan L Ni X Hagler AT 《Journal of computational chemistry》2001,22(15):1782-1800
A class II valence force field covering a broad range of organic molecules has been derived employing ab initio quantum mechanical "observables." The procedure includes selecting representative molecules and molecular structures, and systematically sampling their energy surfaces as described by energies and energy first and second derivatives with respect to molecular deformations. In this article the procedure for fitting the force field parameters to these energies and energy derivatives is briefly reviewed. The application of the methodology to the derivation of a class II quantum mechanical force field (QMFF) for 32 organic functional groups is then described. A training set of 400 molecules spanning the 32 functional groups was used to parameterize the force field. The molecular families comprising the functional groups and, within each family, the torsional angles used to sample different conformers, are described. The number of stationary points (equilibria and transition states) for these molecules is given for each functional group. This set contains 1324 stationary structures, with 718 minimum energy structures and 606 transition states. The quality of the fit to the quantum data is gauged based on the deviations between the ab initio and force field energies and energy derivatives. The accuracy with which the QMFF reproduces the ab initio molecular bond lengths, bond angles, torsional angles, vibrational frequencies, and conformational energies is then given for each functional group. Consistently good accuracy is found for these computed properties for the various types of molecules. This demonstrates that the methodology is broadly applicable for the derivation of force field parameters across widely differing types of molecular structures. Copyright 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1782-1800, 2001 相似文献
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基于偏最小二乘回归的类模型方法用于中药牛黄的真伪鉴别 总被引:1,自引:1,他引:0
针对独立软模式类簇法(SIMCA)在确定主成分数和决策区间时遇到的困难,提出了一种基于PLSR的类模型方法——PLS类模型方法(PLSCM)。通过把类描述问题转化为常见的PLSR问题,采用成熟的蒙特卡罗交互验证法确定模型的隐变量数和决策区间。采用本方法对不同牛黄样品的近红外光谱数据(波长范围4000~9000 cm-1)进行分析,可成功鉴别牛黄的真伪。本方法的可操作性和鉴别准确率均优于经典的SIMCA方法。对于原始光谱数据,PLSCM的训练和预测准确率均为100%,对于经SNV处理的数据,训练和预测准确率分别为99%和100%。 相似文献
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Hua Kuang XiaoLin Hou Hong Miao Gong Zhang JianZhong Shen 《International journal of environmental analytical chemistry》2013,93(6):423-437
Two series of haptens including 3-phenoxybenzoic acid (PBA) and 3-(2-chloro-3, 3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclo-propanecarboxylic acid (CF3MPA) were used to prepare immunogens through attachment of 4-C or 6-C handles. Class selective antibodies were produced by immunising rabbits. Ab502 showed the highest reactivity towards tau-fluvalinate (IC50 1.3 ng mL?1), λ-cyhalothrin (IC50 2.3 ng mL?1), cyfluthrin (IC50 2.2 ng mL?1) and fenpropathrin (IC50 18.5 ng mL?1) among the antibodies in a competitive ELISA. The effects of methanol, pH and salt concentration were optimised for maximum efficiency of the ELISA (Enzyme-Linked ImmunoSorbent Assay). Ab502 (1:80000)/2-OVA-1(0.2 µg mL?1) was chosen for ELISA optimisation. Finally, 0.05 M phosphate buffered saline (PBS) at pH 6.5 containing 30% methanol (v/v) was used to dilute the standards. Target analytes in honey samples were extracted with ethyl acetate by sonication. The samples were spiked with three different concentrations of each compound (tau-fluvalinate, 0.5 ng g?1, 3 ng g?1, 12 ng g?1; λ-cyhalothrin and cyfluthrin 1 ng g?1, 5 ng g?1, 65 ng g?1). The recoveries were 36–59% at the lowest spiking concentration and 61–81% at the higher concentration. This assay might be useful to screen pyrethroid residues in honey or other matrix. 相似文献
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In this paper,an axial dispersion mathematical model is developed to simulate a three-phase slurry bubble column reactor for direct synthesis of dimethyl ether(DME) from syngas.This large-scale reactor is modeled using mass and energy balances,catalyst sedimentation andsingle-bubble as well as two-bubbles class flow hydrodynamics.A comparison between the two hydrodynamic models through pilot plantexperimental data from the literature shows that heterogeneous two-bubbles flow model is in better agreement with the experimental data thanhomogeneous single-bubble gas flow model.Also,by investigating the heterogeneous gas flow and axial dispersion model for small bubblesas well as the large bubbles and slurry(i.e.including paraffins and the catalyst) phase,the temperature profile along the reactor is obtained.Acomparison between isothermal and non-isothermal reactors reveals no obvious performance difference between them.The optimum values ofreactor diameter and height were obtained at 7 m and 50 m,respectively.The effects of operating variables on the axial catalyst distribution,DME productivity and CO conversion are also investigated in this research. 相似文献