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41.
The research and development of catalyst preparation and catalytic technology for fuel alcohol synthesis from syngas have been conducted. The laboratory research work includes the investigation on the effects of preparation method, the composition and K2O content on the catalyst performance. The influences of reaction temperature, pressure, GHSV and feed composition on higher alcohols synthesis have also been investigated. On the basis of laboratory results, the catalysts have been further tesied in micro-pilot reactor under the industrial condition to investigate the effects of commercial preparation of catalyst, the reactor scaling up and (he use of industrial coal based syngas on the fuel alcohol ( mixture of methanol and higher alcohols ) synthesis. The catalyst stability has been tested by a 1000 h continuous operation. These provide the fundamental for further commercial plant design.  相似文献   
42.
脉冲时滞抛物型方程解的振动性   总被引:31,自引:0,他引:31  
燕居让 《数学学报》2004,47(3):579-586
本文研究了两类边界条件下有振动系数的脉冲时滞抛物型方程解的振动性,得到了若干解振动的判别准则。其结果即使用于有固定符号系数的方程,也显著地改进了已有的结果。  相似文献   
43.
Introduction The transferrins are a family of iron-binding proteins which are the requirement of a synergistic anion for the interaction of these proteins with metals.1,2 Although these proteins consist of a single chain of about 700 amino acid resides, they fold into two distinct, homolo-gous lobes connected by a short polypeptide.2-4 Each lobe contains one high-affinity iron-binding site, which is designated as the C-terminal or the N-terminal site, respectively. The ligands for each iron-b…  相似文献   
44.
Binding studies of DNA with Co(Ⅲ) coordination compound   总被引:1,自引:0,他引:1  
The binding of Co(bpy)2dppz3+ to calf thymus DNA was investigated by using absorption and emission spectroscopy,DNA melting techniques,cyclic voltammetry,viscosity and electro-phoresis measurements,where bpy is 2,2'-bipyridyl,dppz is dipyrido[3,2-o:2',3'-c] phenazine.The binding compound shows absorption hypochromicity,fluorescence enhancement,and increasing of DNA melting temperature and the specific viscosity.CV measurement shows the shifts in oxidation-reduction potential and change in peak current with addition of DNA.The compound is also shown to be more efficient photosensitisers for strand breaks in plasmid DNA.  相似文献   
45.
The conformal geometry of regular hypersurfaces in the conformal space is studied.We classify all the conformal isoparametric hypersurfaces with two distinct conformal principal curvatures in the conformal space up to conformal equivalence.  相似文献   
46.
Impregnation, mechanical mixing and hydrothermal treatment methods were used to introduce molybdenum species into the HZSM-5 zeolite. The structure and surface acidity of the catalysts were studied by means of XRD, FT-IR, NH3-TPD, TPR and XPS. The effects of Mo content and reaction time on stream on the aromatization of propane were investigated. It was found that the performance of the Mo/HZSM-5 catalyst prepared by the hydrothermal treatment method was much better than that of the other two catalysts. For example, under the reaction conditions of 823 K and 600 h-1, propane conversion and aromatics selectivity over the catalyst prepared by hydrothermal pretreatment could reach 89.17% and 78.56%, respectively. XRD and XPS results showed that the Mo species in the catalysts prepared by hydrothermal treatment were highly dispersed on the surface of the HZSM-5, and larger amounts of them could penetrate into the HZSM-5 channel, as compared with the other two kinds of catalysts. These factors may be responsi  相似文献   
47.
Using glycerol, glycol and water as solvent, cetyltrimethylammonium bromide (CTAB) as template, tetraethyl orthosilicate (TEOS) as silica source, ethylenediamine (EDA) as base source, mesoporous molecular sieve MCM-41 has been synthesized at room temperature, characterized by X-ray power diffraction and N2 adsorption. Compared with the samples synthesized by glycol and water, the samples synthesized by glycerol have larger pore diameter and high surface areas. Thus glycerol is an efficient solvent for preparing larger pore mesoporous MCM-41.  相似文献   
48.
任蕤  杨频 《中国化学》1999,17(6):625-636
Hydrolysis of DNA is an important enzymatic reaction , but it is exceedingly difficult to mimic in the laboratory because of the stability of hydrolysis of DNA. In this paper, the cleavage activity of complexes formed between Cu(Ⅱ) and four different amino acid or amino acid methyl ester on DNA is studied by gel elec-trophoresis. It is found that DNA could be cleaved by Cu(Ⅱ)-L-His and Cu(Ⅱ)-L-His methyl ester complexes and the efficiency of cleavage is largely dependent on the metal ion-to-ligand ratio. Further experiments show that the cleavage of DNA mediated by Cu(Ⅱ)-L-His complexes occurs via a hydrolytic mechanism and the active chemical species that affects DNA cleavage is proposed to be MI2H and ML2H22 .  相似文献   
49.
采用离子交换法制得的rZSM-5催化剂在催化1-己烯氢甲酰化反应中,副反应己烯加氢生成正己烷较多。用三苯基膦和甲醛在CO/H2反应气中对催化剂进行改性,产物醛的选择性显著提高。CO、H2吸附研究结果表明,改性使催化剂对H2的不可逆吸附及Vco/VH2比降低,而使其对CO的吸附变得完全可逆。反应动力研究表明,总压对改性后催化的活必, 明显影响,但产物醛的正/异比按总压升高而降低。CO分压升高有利于醛的生成和正/异比的提高。提高反应温度和选择性,正/异比降低。通过非线性回归分析,建立速率方程如下:r=kC^0.9 C6 P^0.99H2P^-1.5CO活化能E=43.1kJ/mol.  相似文献   
50.
在非线性动力系统的研究中, Melnikov函数被广泛地用来作为微扰哈密顿系统是否发生次谐或超次谐分岔乃至混沌的判 据. 但是在大多数情况下,经典的Melnikov方法往往只给出存在次谐周期解的结论. 产生 该结果的原因被归之为在经典的Melnikov方法中只采取了一阶近似,因而高阶Melnikov方 法被发展用来判断超次谐周期解的存在性. 本文对一类非自治微分动力系统进行了研究,证 明了在这样一类系统中如果存在周期解则只可能是次谐周期解,超次谐周期解不可能存在, 并进一步证明了在一类平面问题中所定义的旋转(R)型超次谐周期解同样不可能存在.作为 该结论的一个应用,文中考察了几个典型的算例,结果表明现有的二阶Melnikov方法判断 平面扰动系统是否存在超次谐周期解的结论是不恰当的,并提供了一个简单的几何上的解释.  相似文献   
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