初三学生化学三重表征转化的眼动实验研究

化学三重表征研究一直深受国内外学者的重视,目前,初级表征的研究已有一定的理论基础,但是,次级表征（即不同表征水平之间的转化）的研究仍是研究的弱点和难点。纸笔检测、口语报告研究方法都存在一定的局限。为了从信息加工过程研究三重表征间转化的基本特点,采用眼动分析法对12名初三学生进行3×3两因素混合实验。结果显示：（1）在初三上册期末,学优生基本可以进行三重表征之间的直接转化;（2）学中生符号表征较强且依赖于符号表征,表现出“双通道协同加工”现象,符号—宏观、微观转化水平较强,宏观—微观、符号和微观—符号、宏观转化水平较弱;（3）学困生普遍缺乏三重表征的思维和意识,三重表征间的转化水平较低,相比较而言,符号-宏观、微观表征转化稍强于宏观-微观、符号表征转化和微观-符号、宏观表征转化。     

朝鲜族高中生化学三重表征转换能力的调查研究

利用多维分析系统（MAS）,采用2段式问卷并结合课堂观察,以普通高中物质结构与性质模块为内容,调查了延边地区朝鲜族高中生化学三重表征转换能力及其影响因素。结果表明：朝鲜族高中生化学三重表征转换能力由高到低依次为宏观-微观相互转换能力 、宏观-符号相互转换能力、微观-符号相互转换能力。     

基于三重表征的大学有机化学教学策略

从宏观、微观和符号三种表征水平上认识和理解有机化学知识,并建立三者之间的内在联系,进而培养学生“宏观?微观?符号”三重表征思维方式,这对于有效地学习有机化学具有重要的促进作用。结合教学实践,探析了基于三重表征的大学有机化学教学策略。     

化学知识三重表征的话语意义探析*

基于科学哲学和语言学理论,强调化学学科中的三重表征的话语意义,旨在帮助学生将头脑中的三重表征思维用语言科学地表达出来并进行社会性交往。在明确三重表征与话语的关系的基础上,借助于相关教学片段,对三重表征的话语意义(语法学、语义学和语用学意义)进行探析,将宏观微观符号表征中各自的语言内部联系以及彼此间的话语表达关系解构出来,从而全面提升学生在建构、关联及转换表征过程中的交往效率。最后针对相关教学问题,提出了3条教学策略。     

学优生和学困生化学信息迁移题表征的差异研究

化学信息迁移题的表征层次主要有字面表征、模型表征、化学原理表征。本研究通过口语报告、访谈以及问卷调查的形式对高一学生解决化学信息迁移题的过程进行了调查,结果发现,学优生和学困生在解决化学信息迁移题的时候都要依次建立这3种表征层次,然而在建立的各个表征层次上又存在着差异,特别是学优生和学困生在信息提取能力、知识结构以及所采用的解题策略方面存在着显著的差异。     

高中生化学学习中“映象表征”、“符号表征”及其转换能力的调查分析

为了了解中学生化学学习中"映象表征"的能力以及"映象表征"向"符号表征"的转换能力,采用自编问卷对江苏8所四星级高中的高一学生进行了调查。结果表明,学生"映象表征"能力中的"宏观表征"能力强于"微观表征"能力;"映象表征"向"符号表征"转换能力较弱。提出了化学学习中提高学生表征能力的建议。     

转型时期高中生化学学习策略训练的实验研究

研究旨在探讨转型时期高中生化学学习策略训练的有效性。自编《转型时期高中生化学学习策略训练教程》,并运用此材料,对湖南省4所中学174名高一学生进行了一个学期的教学实验,研究表明:（1）在转型时期对高中生进行化学学习策略训练能够有效地提高他们的学习能力,且能提高他们的化学学习兴趣;（2）在转型时期对高中生进行化学学习策略训练的效果,学困生明显优于中等生和学优生,中等生明显优于学优生,但重点中学和普通中学之间没有显著差异。     

化学学习中"宏观-微观-符号"三重表征的研究

“宏观-微观-符号”三重表征是体现化学学科特征的思维方式,能增进学生对化学知识的理解。本研究在对三重表征思维方式进行分析的基础上,采用问卷调查的方法,对不同群体学生化学学习三重表征水平进行了探查和分析,为化学教学提供了一个新的视角。     

三重表征视域下的化学学习研究考查

梳理了三重表征研究范式下部分化学学习研究成果。基于三重表征,研究者细致考查学生在宏观表征、微观表征和符号表征等单维度化学学习中遇到的困难;结合信息加工模型,解释了化学学习机制,形成对化学学习的动态认识,指出以上研究中尚待完善之处,以期为化学学习的深入研究提供借鉴。     

提升三重表征融合能力的教学策略研究——以高中化学“电解质的电离”教学为例

结合高中化学"电解质的电离"中丰富的教学活动,以感知体验化、微观可视化、知识本源化、认识观念化和符号意义化为教学策略,丰富和深化宏观表征和微观表征,实现化学三重表征的高度融合。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.