群的根性的一个问题

假设（R）是群的根性,N是群G的正规子群,记N^-/N＝RR（G/N）.主要利用群的根性的性质来解决哪种根性具有特征性质N1N2^-＝N1^-N2^-这个问题.     

测定水中硫酸根方法的概述

介绍了测定水中硫酸根的方法和几种常用方法在水质分析中的应用。     

海图上岛屿自动选取的一种模型

岛屿的自动选取是实现岛屿自动综合的前提，在分析岛屿选取特点的基础上，给出了岛屿自动选取模型。该模型采用了系统聚类和Vironoi图两项关键技术，在整体选取的基础上实施局部控制，使得岛屿选取更加趋向客观实际。     

Atmospheric chemistry of alkanes

The reactions of the alkanes under atmospheric conditions and in the presence of oxides of nitrogen are reviewed and evaluated. Particular emphasis is placed upon their subsequent reactions after the initial OH radical reaction under conditions where the alkyl peroxy radicals produced react predominantly with NO, rather than with HO₂ and/or RO₂ radicals. Methods are discussed for estimating the overall OH radical rate constants, the number of molecules of NO consumed per alkane molecule reacted, and the products formed and their yields.     

The photo-oxidations of propyl acetates in synthetic air-HONO-NO x mixtures: Product formation studies and proposed kinetic mechanisms

The formation of products following the hydroxyl radical initiated photo-oxidations of n-and isopropyl acetates has been studied. Mixtures of synthetic air containing a few ppm of nitrous acid, nitric oxide, nitrogen dioxide and one of the propyl acetates were irradiated with sunlamps in a Teflon bag smog chamber. The decay of reactants and the formation of products was monitored by chemiluminescent analysis or by gas chromatography. The major primary products from the photo-oxidation of n-propyl acetate are acetaldehyde and propionaldehyde while from isopropyl acetate they are acetone and methyl nitrate. It was not possible to analyse for formaldehyde, an expected primary product in these systems. The nature and distribution of products indicate that a significant fraction of primary products arise from decomposition reactions of the alkoxy-type radicals generated following the initial attack of hydroxyl radicals on the esters. The derived reaction stoichiometries (molecules of NO oxidised per molecule of ester reacted) are also consistent with the proposed mechanisms.     

高温下甲基丙烯酸正丁酯ATRP的合环失活

以2-溴代异丁酸乙酯[2-(E iB)-B r]为引发剂,CuB r/2,2’-bpy为催化体系,进行了甲基丙烯酸正丁酯(n-BMA)在异丙醇(IPA)/水中的原子转移自由基聚合,在16.5~100℃范围内研究了温度对聚合反应活性特征的影响。动力学结果表明,低温时反应有良好可控性,温度升至85℃以上时,聚合反应呈现出一系列非活性特征,聚合进行到一定程度后转化率不再增加,所有的链都成为死链。红外光谱的结果证明,较高温度时处于休眠态的增长链发生了合环反应,导致了增长链的永久失活。     

Development and deployment of an instrument for measurement of atmospheric peroxy radical by chemical amplification

An instrument for measurement of peroxy radical by chemical amplification (PERCA) has been devel- oped at Peking University (PKU) and deployed in several field campaigns. PKU PERCA measures per- oxy radical via amplification of NO2 by peroxy radical in the presence of NO and CO through a chain reaction. The amount of amplified NO2 is detected by a NO2-luminal chemiluminescence detector. The chain length (CL) of 75±20 (1σ ) was determined routinely during field campaigns using a HO2 source from photolysis of...     

半透产O_2￣(·-)体系的建立

原有的产Ｏ·－２体系不适宜用作生物大分子的损伤研究。本实验以半透膜将产Ｏ·－２液相与待作用的样品液相分隔,使产Ｏ·－２液相中的组分选择性地透过至样品液相,对样品进行作用。这种半透产Ｏ·－２体系非常适于蛋白质、核酸等生物大分子损伤后的结构变化分析研究。本文给出了该体系用于生物大分子损伤以及结构变化研究的实验常数     

A Three-Dimensional Simulation of HO x Concentrations Over East Asia During TRACE-P

The Models-3 Community Multi-scale Air Quality modeling system (CMAQ) coupled with the Regional Atmospheric Modeling System (RAMS) is used to simulate three-dimensional concentration distributions of hydroxyl (OH) and hydroperoxyl (HO₂) radicals over the western Pacific Ocean during the NASA Transport and Chemical Evolution over the Pacific (TRACE-P) field campaign. Modeled values of OH and HO₂ and their closely related chemical species and photolysis rates are compared with observational data collected onboard the DC-8 aircraft. Comparison shows that the model reasonably reproduced these observed values over a broad range of conditions with an overall tendency to overestimate the measured OH and HO₂ by a factor of 1.56 and 1.24, respectively. A case study of OH, HO₂ and their closely related chemical species and photolysis rates along the DC-8 flights 11 and 12 conducted on 17–18 March 2001 shows that the model reproduces the temporal and spatial variations reasonable well, and produces more reliable OH and HO₂ concentrations in the polluted environment than in the clean marine boundary layer.