GLOBAL ATTRACTIVITY IN A PERIODIC DELAY SINGLE SPECIES MODEL

In this paper, we establish the existence of a positive periodic solution for a periodic delay single species population growth model, and obtain sufficient conditions for the periodic solution to be globally attractive.     

NO在氧化铝负载的Pd催化剂上吸附的TPD-MS研究

消除汽车尾气中的氮氧化物(NOx)对保护大气环境有着重要意义.为了除去NOx,已经进行了许多卓有成效的研究,例如NOx在分子筛上的直接分解和催化还原,在贵金属三效催化剂上的还原等.     

三正辛胺与丙酸的萃取机理

三辛胺;离子对萃合物;三正辛胺与丙酸的萃取机理     

正丁烷选择氧化过程中VPO体系的表面物种

用漫反射傅立叶变换红外光谱法,研究了VPO催化剂上正丁烷选择氧化制顺酐的表面物种及催化反应过程。催化剂暴露在1．5％n-C4 21％02＋N2的流动混合气中,流量为50mL/min,温度100－400℃,在催化剂表面上未观察到吸附的正丁烷,但发现了吸附的顺酐和COx。同时,检测到吸附的马来酸和高活性的烯烃物种。     

The Stability Constants of Complexes of BDBPH- Metals and Species Distributions

The study on the design and synthesis of model compounds for metalloproteins has been a subject of extensive investigation1. During the last decade, a number of synthetic structural models for some kinds of metalloproteins with several types of ligands have been reported in literature2,3,4. We have recently reported a new 24-membered hexaazadiphenol macrocyclic ligand, 3,6,9,17,20,23-hexaaza-29,30-dihydroxy-13,27-dimethyl-tricyclo [23,3,1,111,15] triaconta-1 (28),11,13,15 (30),25,26-hexaene,…     

共聚焦激光扫描显微术研究天花粉蛋白对小鼠胚胎细胞的作用机制

天花粉蛋白是从中草药Ku楼根中根中取的一种核糖体失活蛋白,具有致流产、抗肿瘤和抗HIV功能。本文应用共聚焦激光扫描显微术结合特异性荧光探针2',7'-二氯荧光黄双乙酸酯和Fluo-3AM,观察了天花粉蛋白作用于小鼠胚胎细胞过程中活性氧自由基和细胞内钙离子浓度的变化。实验结果表明,天花粉蛋白能诱导小鼠胚胎细胞钙浓度升高和产生活性氧自由基,并且天花粉蛋白能有效抑制小鼠胚胎细胞的分裂,为天花粉蛋白的致流产提出了新的机制。     

Method for the calculation of the species balance in the reaction zone

A class of processes for which the problem of species balance can be solved without using any assumptions concerning the mechanism of the chemical event of the reaction was found in the problem of species balance in the reaction zone. The mathematical statement of the problem in this case was discussed; it was shown that the solution is mainly determined by the system geometry. The method for reducing the problem to determination of the probability of species entering the chemical event zone is substantiated; this can be done by the Green function method.     

Characterization of transient species in laser photolysis of aromatic amino acids using acetone as photosensitizer

The photochemical processes of aromatic amino acids were investigated in aqueous solution using acetone as photosensitizer by KrF (248 nm) laser flash photolysis. Laser-induced transient species were characterized according to kinetic analysis and quenching experiments. The intermediates recorded were assigned to the excited triplet state of tryptophan, the radicals of tryptophan and tyrosine. The excited triplet state of tryptophan produced via a triplet-triplet excitation transfer and the radicals arising from electron transfer reaction has been identified. Neither electron transfer nor energy transfer between triplet acetone and phenylalanine can occur in photolysis of phenylalanine aqueous solution which contains acetone. Furthermore, triplet acetone-induced radical transformation: Trp/N-Tyr→Trp-Tyr/O was observed directly in photolysis of dipeptide (Trp-Tyr) aqueous solution containing acetone, and the transformation resulting from intramolecular electron transfer was suggested.     

1-丁烯齐聚反应(Ⅸ)——羧酸镍/乙基氯化铝催化体系反应机理的讨论

用乙酸镍、2-乙基己酸镍、二乙基氯化铝、倍半乙基氯化铝等组成Ziegler-Natta催化剂催化丁烯齐聚.测定了二聚物组成,讨论了活性物种的形成过程,推导了反应机理.     

Methane Oxidative Coupling over Fluoride-Promoted Cerium Oxide Catalysts

Since the pioneer work of Keller and Bhasin on the oxidative coupling of methane, many catalyst systems, mostly based on the oxides or complex oxides of alkali metals, alkali earth metals and rare earth metals, have been developed. In some studies, halides, especially chlorides and bromides, have been added to these oxides in order to improve the catalvtic activitv and selectivity. howevek of