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191.
LiZHANG NaLI FengLinZHAO KeAnLI 《中国化学快报》2004,15(6):671-674
The interaction between heparin and neutral red was investigated by molecular spectroscopic methods. The change of all spectra suggested that positively charged neutral red had interacted with negatively charged heparin. The study of influence factors indicated that electrostatic force and hydrophobic bond might be involved in the interaction. The total binding number per disaccharide unit and intrinsic binding constant were obtained using Scatchard model. 相似文献
192.
金属的催化活性不仅取决于该金属的价态分布,电子结构,而且强烈地依赖于金属的分散性。载Ni沸石体系,由于金属离子的难还原性和还原金属粒子的流动性,在制备过程中不可避免会引起粒子的迁移,聚集,并形成大晶粒,甚至导致金属的双分散系。迄今为止,关于金属粒子的聚集或大晶粒的形成尚无一致看法。 相似文献
193.
CHEN Xiao ZHANG Yong-Xin DU Da-Ming HUA Wen-Ting 《有机化学》2003,23(Z1):25-26
The enantioselective reduction of prochiral ketones with borane in the presence of a chiral ligand leading to enantiomerically pure secondary alcohols has received considerable attention in recent years. [1] Enantiomerically pure secondary alcohols are important intermediates for the synthesis of various other organic compounds such as halides, esters, ethers, ketones and amines. To the best of our knowledge, the use of pyridine prolinol derivatives in the reduction of ketones has not been reported so far. Thus, it should be of interest to investigate the catalytic a bility of such ligands. We have an ongoing project in the synthesis and application of chiral pyridine derivatives in chiral molecular recognition[2] and we want to evaluate the effect resulting from the introduction of a pyridinyl moiety onto the catalysts. We expect that the cooperation of pyridine unit and chiral prolinol unit in new ligands may result in unique properties for catalytic reaction. 相似文献
194.
Effects of sugar inhibition on cellulases and β-glucosidase during enzymatic hydrolysis of softwood substrates 总被引:1,自引:0,他引:1
Zhizhuang Xiao Xiao Zhang David J. Gregg John N. Saddler 《Applied biochemistry and biotechnology》2004,115(1-3):1115-1126
A quantitative approach was taken to determine the inhibition effects of glucose and other sugar monomers during cellulase
and β-Glucosidase hydrolysis of two types of cellulosic material: Avicel and acetic acid-pretreated softwood. The increased
glucose content in the hydrolysate resulted in a dramatic increase in the degrees of inhibition on both β-Glucosidase and
cellulase activities. Supplementation of mannose, xylose, and galactose during cellobiose hydrolysis did not show any inhibitory
effects on β-Glucosidase activity. However, these sugars were shown to have significant inhibitory effects on cellulase activity
during cellulose hydrolysis. Our study suggests that high-substrate consistency hydrolysis with supplementation of hemicellulose
is likely to be a practical solution to minimizing end-product inhibition effects while producing hydrolysate with high glucose
concentration. 相似文献
195.
简便快速的硫化氢测定法 总被引:1,自引:0,他引:1
本文提出了有一种简易快速测定剂来测定水样中的硫化氢的方法。该法的检出限为0.1mg/L,对1.01mg/L的H2S样品7次测定的相对标准偏差<4.1%,1h能测定12个样品。用本测定了几种水样中的H2S含量,回收率为84%-105%。应用它可上标准法的4h左右缩短到5min;使分析成本降低9/10;不需配制一系列分析试剂和仪器,只需一支小型塑料管和几片药片,便于渔业水质和环境水质的野外现场监测。 相似文献
196.
八配位钇(Ⅲ)-反式-1,2-环己二胺四乙酸配合物NH4[Y(trans-CYDTA)(H2O)2]·4.5H2O的合成及分子结构 总被引:10,自引:0,他引:10
In this paper, the molecular and crystal structures of the NH4[Y(trans CYDTA)(H2O)2]·4.5 H2O(trans-CYDTA=trans 1,2-cyclohexanediaminetetraacetic acid) are reported. The crystal data are as follows: Triclinic system, P1space group,a=0.8599(6)nm,b=1.0021(7)nm,c=1.4370(9)nm,α =88.095(13)°,β =75.559(1)°,γ =88.344(12)°,V=1.1981(14)nm3,Z=2, M=708.68,Dc=1.570g· cm-3, μ =2.506mm-1 and F(000)=590. The final R1 and wR2 are 0.0571 and 0.1350 for 4205 [I >2.0σ (I)] unique reflections and 0.1007 and 0.1615 for all 4981 reflections, respectively. In the title complex, the anion [Y(trans-CYDTA)(H2O)2]- has an eight coordination structure with distorted square antiprism. The trans CYDTA which acts as a hexadentate ligand with four Oatoms and two Natoms and two H2O molecules directly coordinate to central metal Y(Ⅲ) ion. It can be known that the Y(Ⅲ) ion can form an eight coordinate compound with aminopolycarboxylic acid ligands in addition nine coordination structure. 相似文献
197.
Zhengping Hao Lidun An Junling Zhou Hongli Wang 《Reaction Kinetics and Catalysis Letters》1996,59(2):295-300
Supported gold catalyst for eliminating hydrogen from CO2 feed gas in the production of urea is found to be superior to other industrial catalysts (e.g. Pt/Al2O3 and PdPt/Al2O3) in catalytic activity and resistance to sulfur poisoning. 相似文献
198.
DongJunWANG QunLUO DanDanJIA XiaoDongLI XinQiouWANG YongHuang ZhenZHEN XinHouLIU 《中国化学快报》2003,14(12):1306-1308
The hydrolysis of tetraethoxysilane (TEOS) occurred on the surface of poly(methyl methacrylate) (PMMA) microshperes immediately after these microshperes were prepared in TEOS. Micron-sized hollow SiO2 spheres were obtained by calcination of the coated PMMA microshperes. It was found that the final hollow spheres were constituted by small SiO2 particles. 相似文献
199.
毛细管电泳法快速分离和检测肠毒性大肠杆菌 总被引:4,自引:0,他引:4
建立了快速分离和检测引起仔猪腹泻的肠毒性大肠杆菌K88、K99和 987P细菌细胞的毛细管区带电泳方法 ,并进行了腹泻仔猪粪便中肠毒性大肠杆菌的应用检测分析。结果表明 ,在电泳缓冲液为 0 0 5mol/LNa2 CO3 NaHCO3(pH 9 9)、分离电压为 1 4 1kV、检测波长为 2 1 0nm的电泳条件下 ,E coliK88、K99和 987P的细胞分别具有单一、稳定的特征谱峰 ,其保留时间的相对标准偏差RSD≤ 0 9% ;在确定的实验条件下 ,实现了腹泻仔猪粪便中肠毒性大肠杆菌的快速检测分析 ,发现将出生 5d~ 6d的腹泻仔猪粪便引入培养基中增殖后主要检出K88。 相似文献
200.
采用共沉淀水热法制备了镍铝铈三元复合层状氢氧化物.详细探讨了合成体系pH值、Ce/Al比及陈化条件对合成产物物相的影响;通过XRD,ICP,TG-DTA手段研究了合成物物相、组成及热行为.考察了以合成物为前驱体经焙烧后转化为镍铝铈复合金属氧化物在催化消除NO反应中的应用.实验结果表明,合成镍铝铈三元复合层状氢氧化物的适宜条件是:M2 /M3 =2,Ce/Al=0.07~0.75,pH=5.5~6.9,水热处理条件为110℃,5 h;在pH=5.5~6.9条件下,合成原料配比不同,产物物相相同,但组成不同;合成物热稳定性较差,在T=100~400℃之间,层间吸附水及层间平衡阴离子NO3-脱去,转化为复合氧化物,将此氧化物应用于NO消除反应中,表现出高的低温活性,400℃进行反应,NO转化率达95%,N2选择性几乎100%. 相似文献