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131.
连续一级反应的热动力学研究 总被引:1,自引:0,他引:1
本文把时间比法引入热动力学研究,建立了连续一级反应的热动力学研究法,并用来研究了一个连续反应体系的热动力学,验证了该方法的正确性. 相似文献
132.
Lizeng PengHuawei Liu Tao ZhangFengzhi Zhang Tiansheng MeiYi Li Yulin Li 《Tetrahedron letters》2003,44(27):5107-5108
A stereoselective synthesis of brassinolide, which involves construction of the side chain by a highly stereoselective aldol reaction between 20S-6β-methoxy-3α,5-cyclo-5α-pregnane-20-carboxaldehyde 2 and ketone 3 or 4 catalyzed by l-proline, is described. 相似文献
133.
脂肪族酰胺二元醇的合成与表征 总被引:3,自引:1,他引:3
以DL-乳酸、ε己内酯及乙二胺和己二胺为原料合成了四种结构的脂肪族酰胺二元醇,并用IR,^1HNMR,DSC对酰胺二元醇的结构进行了表征。 相似文献
134.
A novel poly(vinyl alcohol) grafting 4-vinylpyridine self-gelatinizable copolymer was adapted to immobilize glucose oxidase. The reduction of hydrogen peroxide (H2O2) was detected at a Prussian Blue (PB) modified graphite electrode. A stable and sensitive glucose amperometric biosensor is described. The copolymer is a good biocompatible polymer in which the glucose oxidase retains high activity. Moreover, the copolymer can adhere firmly to the inorganic PB membrane. The sensor showed an apparent Michaelis-Menten constant of 18 +/- 0.2 mM and a maximum current density of 1.14 microA cm-2 mM-1. The linear range is from 5 microM to 4.5 mM glucose and the detection limit is 0.5 microM glucose. The catalytic efficiency of PB for the reduction of H2O2 is higher than that for the oxidation of H2O2. Glucose concentrations in serum samples from healthy persons and diabetic patients were determined using the sensor. The results compared well with those provided by the hospital using a spectroscopy method. 相似文献
135.
Lin Jia Hui Yang Jun Deng Junmei Chen Yuan Zhou Pan Ding Leigang Li Na Han Yanguang Li 《中国化学》2019,37(5):497-500
Electrocatalytic carbon dioxide reduction holds great promise for reducing the atmospheric CO2 level and alleviating the energy crisis. High‐performance electrocatalysts are often required in order to lower the high overpotential and expedite the sluggish reaction kinetics of CO2 electroreduction. Copper is a promising candidate metal. However, it usually suffers from the issues of poor stability and low product selectivity. In this work, bimetallic Cu‐Bi is obtained by reducing the microspherical copper bismuthate (CuBi2O4) for selectively catalyzing the CO2 reduction to formate (HCOO–). The bimetallic Cu‐Bi electrocatalyst exhibits high activity and selectivity with the Faradic efficiency over 90% in a wide potential window. A maximum Faradaic efficiency of ~95% is obtained at –0.93 V versus reversible hydrogen electrode. Furthermore, the catalyst shows high stability over 6 h with Faradaic efficiency of ~95%. This study provides an important clue in designing new functional materials for CO2 electroreduction with high activity and selectivity. 相似文献
136.
Xu J Jiao P Deng D Zhang Q Tsang CW Chan AS 《Rapid communications in mass spectrometry : RCM》2002,16(12):1174-1179
The mass spectrometric fragmentation behaviour of five pairs of (R,R)- and (S,S)-4,5-bis(benzoxazol-2-yl)-2,2-dimethyl-1,3-dioxolane derivatives, one pair of (R,R)- and (S,S)-4,5-bis(benzothiazol-2-yl)-2,2-dimethyl-1,3-dioxolanes, and three pairs of (R,R)- and (S,S)-N,N'-bis(2-hydroxyaryl)-2,2-dimethyl-1,3-dioxolane-4,5-dicarbamides, all important compounds for asymmetric catalysis (P. Jiao et al., Tetrahedron Asymmetry 2001; 12: 3081), has been studied with the aid of mass-analyzed ion kinetic energy spectrometry and accurate mass measurements under electron impact ionization conditions. The spectral observations have been rationalized in terms of fragment ion structures and fragmentation mechanisms that will provide an aid to spectral interpretation for new compounds of this type. 相似文献
137.
用超高真空程序升温反应谱和瞬时应答方法研究了乙二醇在电解银表面的氧化,实验表明,室温下乙二醇吸附在电解银表面,并在343K分解给出一组产物群,预吸附氧与乙二醇反应时,在343K,433K和612K处给出三组产物群,它们分别对应于不同的表面反应,并给出了电解银催化乙二醇制乙二醛的活性结果。 相似文献
138.
A new separation matrix, consisting of polymer poly(N-isopropylacrylamide) (PNIPAM) and small molecule additive mannitol, was used for double-stranded (ds) DNA and plasmid DNA separation by capillary electrophoresis. The matrix had a low viscosity, which made it very easy to handle. The additive mannitol dramatically enhanced the sieving performance of PNIPAM in TBE buffer. The optimal mannitol concentration 6% in polymer solution, was determined with the consideration of both speed and resolution. A resolution of 0.95 was achieved on the separation of 271/281 bp in the phiX174/HaeIII digest by using 1.5% PNIPAM + 6% mannitol, while the supercoiled, linear and nicked conformers of lambda plasmid were separated in 1% PNIPAM + 6% mannitol, demonstrating the potential use of this new matrix for effective DNA separations. The dramatic impact of mannitol on sieving performance of PNIPAM solution was investigated. pH dependent self-coating ability of PNIPAM was revealed. The presence of mannitol in TBE buffer decreased the pH of the buffer, which led to more efficient self-coating ability of PNIPAM probable due to the formation of hydrogen bonds between PNIPAM molecules and silanol groups at the silica wall. 相似文献
139.
Preparation, characterization and properties studies of quinine-imprinted polymer in the aqueous phase 总被引:4,自引:0,他引:4
The uniform-sized spherical molecularly imprinted polymers were successfully prepared through molecular imprinting technology
by two-step seed swelling and mini-emulsion polymerization in the aqueous condition using quinine as template molecules and
methacrylic acid (MAA) as functional monomer. The polymers were characterized by IR spectra, thermal-weight analysis, scanning
electron microscope and laser particle size analysis. The properties of imprinted polymers were investigated in different
organic phases and aqueous media. In the organic media, results suggested that polar interactions (hydrogen bonding, ionic
interactions) between acidic monomer/polymer and template molecules are mainly responsible for the binding and recognition;
whereas in the aqueous medium, a considerable recognition effect was also obtained where the ionic (electrostatic) interaction
and hydrophobic interaction play an important role. The experiments of binding different substrates indicated that the MIPs
possessed an excellent rebinding ability and inherent selectivity to quinine.
__________
Translated from Zhongshan Dcocue Xuebao/Acta Scientianum Natralium University Sunyatseni, 2005, 44(3)(in Chinese) 相似文献
140.
Xu X Zhao J Jiang D Kong J Liu B Deng J 《Analytical and bioanalytical chemistry》2002,374(7-8):1261-1266
A novel hydrogen peroxide biosensor was developed based on the immobilization of horseradish peroxidase (HRP) in a TiO(2) sol-gel matrix on an electropolymerized phenazine methosulfate (PMS) modified electrode surface. Such membranes are of interest due to their high surface area, biological compatibility, and ease of fabrication. HRP entrapped in the TiO(2) matix was stable and retained its activity to a large extent. Cyclic voltammetry and amperometric measurements were employed to demonstrate the feasibility of electron transfer between immobilized HRP and the glassy carbon electrode via electropolymerized PMS. The influence of various experimental parameters such as operating potential, pH, temperature, and stability was investigated for optimum analytical performance. The biosensor provided a wide linear calibration range from 4.0x10(-6) M to 1.0x10(-3) M, with a detection limit of 8.0x10(-7) M at a signal-to-noise ratio of 3. The sensor retained 80% of its original activity after two months of operation. 相似文献