关于环Zn上的椭圆曲线

基于环 上椭圆曲线的射影化定义,深入研究了 上椭圆曲线点群中点的结构形式,讨论了点的加法的射影化定义和仿射化定义,指出在仿射化定义条件下文献[1]和[3]在定义点的加法时存在的一个认识上的错误,给出了仿射化定义条件下两种定义方法之间的区别与联系,最后针对仿射化定义条件下某些点的加法无意义的情形进行了讨论,并分析了导致这种情形的根本原因。     

WFGD工艺典型脱硫添加剂应用探讨

鉴于石灰石湿法烟气脱硫(WFGD)技术在脱硫市场的主导地位,对镁、DBA、蚁酸等3种典型脱硫添加剂的作用机理、工业应用等方面作了介绍。用理论和实践证明脱硫添加剂确实能够提高SO2的吸收率和石灰石等吸收剂的利用率,并且具有降低结垢和堵塞风险、节约安装及运行成本的功效。     

An in-depth investigation on the formation of nanoporous silica microspheres in diluted dodecylamine solutions

The morphology and textural characteristics of silica products formed via the hydrolysis and condensation of tetraethyl orthosilicate in increasing diluted dodecylamine solutions have been investigated. The results show that the pH values of the synthesis media increase with the initial additions of water. The formation of silica speeds up as the solution is diluted. As a result, microporous silica microspheres with increasing surface areas, pore volumes, pore and particle sizes are formed by a monomer addition mechanism. Further increases in the amount of water result in the decrease of the concentrations of OH^?. Consequently, the formed silica seeds become less active and the diffusion of silica species is accelerated. The monomer addition process thus becomes difficult. The self-nucleation of silica species leads to the formation of large quantities of primary silica nano particles. In order to minimise the internal energy of the reaction system, the nanoparticles aggregate to form micrometre-sized silica microspheres with a relatively loose structure. The synthesised microspheres can be used in the removal of organic pollutants in water. It is shown that the nanoporous silica microspheres formed by the aggregation mechanism have a faster dye adsorption rate and a higher adsorption capacity than those formed by the monomer addition mechanism.     

Green chemistry: microwave-assisted facile synthesis of 6-imino-1,3,4-thiadiazenes from reaction of thiocarbohydrazones with malononitrile dimer

The reactions of thiocarbohydrazones with malononitrile dimer under microwave irradiation are reported. These reactions give 6-imino-1,3,4-thiadiazines in good yields. The structures of products were elucidated by MS, IR and NMR spectra together with elemental analyses. The reaction mechanism was discussed.     

加成型有机硅反应过程的实时监测

用实时傅里叶变换红外光谱仪（FTIR）对乙烯基硅橡胶和含氢硅油的加成聚合过程进行了表征，得到了基团浓度消耗比反应时间变化的曲线，结果表明，在反应过程中，硅氢基与乙烯基的浓度减少呈非线性关系，这可能是硅氢基在反应过程中与空气中的物质进行了反应，从而在消耗量上较乙烯基多的缘故。     

Cultural differences in complex addition: Efficient Chinese versus adaptive Belgians and Canadians.

In the present study, the authors tested the effects of working-memory load on math problem solving in 3 different cultures: Flemish-speaking Belgians, English-speaking Canadians, and Chinese-speaking Chinese currently living in Canada. Participants solved complex addition problems (e.g., 58 + 76) in no-load and working-memory load conditions, in which either the central executive or the phonological loop was loaded. The authors used the choice/no-choice method to obtain unbiased measures of strategy selection and strategy efficiency. The Chinese participants were faster than the Belgians, who were faster and more accurate than the Canadians. The Chinese also required fewer working-memory resources than did the Belgians and Canadians. However, the Chinese chose less adaptively from the available strategies than did the Belgians and Canadians. These cultural differences in math problem solving are likely the result of different instructional approaches during elementary school (practice and training in Asian countries vs. exploration and flexibility in non-Asian countries), differences in the number language, and informal cultural norms and standards. The relevance of being adaptive is discussed as well as the implications of the results in regards to the strategy choice and discovery simulation model of strategy selection (J. Shrager & R. S. Siegler, 1998). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Competition Kinetics of Unbranched Chain Processes of Free-Radical Addition to Double Bonds of Molecules with the Formation of 1:1 Adducts

Abstract

Based on a kinetic model involving competing parallel reactions for free-radical addition to the double bond of a molecule with the formation of 1:1 adduct and participation of three radical types in the chain propagation, versions of the rate equation with 1 - 3 measurable parameters are derived. These versions make it possible to describe the nonmonotonic (with maximum) dependence of the formation rate of an addition product on concentration of the unsaturated compound. The unbranched chain process occurs in binary liquid systems comprising saturated and unsaturated components at comparable concentrations. Application of the competition kinetics of free-radical addition to oxidation of some hydrocarbons is discussed when the reaction that competes with chain propagation reactions involving the alkylperoxy radical RO₂ gives the cyclic alkylhydrotetraoxy radical [R(_?H)O₄H] as a less reactive radical inhibiting the chain process of formation of the main products of oxidation.     

Chemical Modification of Fiber-forming Polymers Based on Recombination Addition Reactions

Abstract

The essence of chemical modification processes of fiber-forming polymers based on recombination addition reactions involves preliminary sorption of low-molecular components by the fiber being in a high elasticity state with the subsequent transfer of interacting substances into a free radical state as a result of chemical or radiation initiation. Recombination of activated parts then leads to the fixation of a low-molecular component in a polymer matrix.

Various versions of these reactions based on modifications of fibrillar proteins (fibroin and keratin). polyamides. cellulose and its esters, polyvinyl alcohol with ionogenic (cationic and anionic) and non-ionogenic (disperse) dyes of different classes have been considered.     

Effects of preparation method on cyclic stability and CO2 absorption capacity of synthetic CaO-MgO absorbent for sorption-enhanced hydrogen production

A novel and economical method for preparing CaO-based high-temperature CO₂ absorbents for sorption-enhanced hydrogen production is introduced. CaO-MgO absorbents prepared by the co-precipitation method show excellent cyclic stability but poor absorption capacity (∼8-14 g CO₂/100 g absorbent). An additional hydration process provided spacious CO₂ pathways resulting in a significant increase of the absorption capacity (∼17.4-47.8 g CO₂/100 g absorbent) with excellent cyclic stability. As the MgO content increased, the absorption ratio of the absorbent and the degree of CaO conversion also increased. In addition, XRD analysis revealed that the hydration process followed by calcination at 900 °C led to the formation of a partial solid solution in the CaO-MgO absorbent containing 25 wt% MgO.     

The effect of reaction product on the rate of addition of acetic acid to epichlorohydrin in the presence of chromium(III) acetate

The kinetics of addition of acetic acid to epichlorohydrin carried out in the presence of both the reaction product and chromium(III) acetate catalyst have been studied. At an equimolar ratio of reagents the dilution of the reacting mixture with the reaction product has been found not to affect the reaction order. The presence of product in the starting mixture, as well as temperature increase, considerably reduces the selectivity of reaction. Side reactions of epichlorohydrin are activated. Activation energy, enthalpy and entropy of the reaction all decrease in the presence of reaction product. © 2001 Society of Chemical Industry