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941.
Recently, the liquid-phase synthesis of small organic compounds has been a preferable strategy due to its combination with the advantage of solution-phase and solid-phase methods1. Among the various soluble polymers, polyethylene glycol (PEG) is the most useful as support. It has been reported that PEG bound substrates could also play the role of phase-transfer catalyst (PTC) in some reactions2. Herein we reported that palladium-catalyzed coupling reactions could be taken place smoothly… 相似文献
942.
利用电场作用通过交流和直流等离子体在低温、常压和低功率下催化反应将甲烷直接转化为碳二烃(乙烷、乙烯、乙炔)。考察了在对称电场作用下催化剂的催化性能。实验结果表明,在交流电场作用下,碳二烃选择性差别不大;甲烷转化率的大小顺序为: MnO_2/Al2O3>Ni/Al2O3>MoO_3/Al2O3>Al2O3>Ni/Al2O3>MoO_3/Al2O3>Ni/NaY>Pd/ZSM-5>Ni/H4Mg2Si3O4>Ni/ZSM-5>Co/ZSM-5>无催化剂:在直流电场作用下,碳二烃选择性差别也不大(除Ni/NaY外),甲烷转化率的大小顺序为: Ni/A12O3>Ni/H4Mg2Si3O4>Ni/ZSM-5>Co/ZSM-5>MnO2/A12O3>MoO3/A12O3>Ni/NaY>无催化剂>Pd/ZSM-5。 相似文献
943.
研究了明胶水凝胶在绝缘硅油中的电场响应行为。结果表明,在硅油中,明胶水凝胶在外加高压直流电场作用下可发生运动,其运动由转动和平动两部分组成。存在一个运动所需的最小阈值电场,只有外加电场在此阈值以上时,才可观察到水凝胶明显的运动。水凝胶的运动速度随外加电场的增大而增大,其运动可通过外加电场的大小来调控。由硅油很稳定且在电场中会电解,因此避免了传统电场驱动水凝胶在水介质中响应时不可避免的电解缺点,为建立一种新的电响应凝毅然驱动方式提供了可能。 相似文献
944.
A procedure for pH-metric determination of the limiting adsorption of OH groups (A
OH) by FeIII, ZrIV, CrIII, and InIII oxyhydroxide hydrogels from 0.1 and 1.0 M solutions of NaCl is described. Data on the molecular area occupied by a single OH group on the hydrogel surface (S
OH) and the S
spec values, which were calculated from A
OH and S
OH, are presented. The S
spec value does not depend on the pH of hydrogel precipitation; the true S
spec value can be determined only from sorption of the OH groups at the actual point of zero charge of the hydrogel. The A
OH values for hydrogels were found to change only slightly during aging of hydrogels in electrolyte solutions. 相似文献
945.
多电极电容传感器的参数优化设计 总被引:4,自引:0,他引:4
将电容层析成像中多电极电容传感器的参数设计作为一个以均匀敏感度为目标 ,并受电容测量技术及制造工艺水平限制的有约束条件的最优化问题处理 .提出了用正交设计法对传感器进行计算机辅助设计 ,可以方便、快速地找到一组最优参数 ,能够较好地克服以前的设计方法所需计算量大的缺点 .实验结果表明 ,该设计方法具有较强的实用性 . 相似文献
946.
Study on Reduction of Energy Consumption in Pulsed Corona Discharge Process for NOx Removal 总被引:4,自引:0,他引:4
Chung Jae-Woo Cho Moo-Hyun Son Byung-Hak Mok Young-Sun Namkung Won 《Plasma Chemistry and Plasma Processing》2000,20(4):495-509
We investigated the reduction of electrical energy consumption in thepulsed corona discharge process for the removal of nitrogenoxides. Hydrocarbon chemical additives used in the laboratory-scaleexperiment are responsible for the enhancement of the NO conversionthrough the chain reactions of free radicals, such as, R, RCO, RO,and others. Electrical energy consumption per converted NO moleculehas a minimum value of 17 eV when pentanol is injected. When ethyleneand propylene are injected, 30 and 22 eV of electrical energy consumptionare required for the conversion of a NO molecule, respectively. The ratioof the pulse-forming capacitance (Ce) to the reactor capacitance (CR)plays an important role in the energy transfer efficiency to thereactor. The maximum energy transfer efficiency of approximately 72%could be obtained by the pulse-forming capacitance, which is 3.4 timeslarger than the reactor capacitance; the maximum NO conversionefficiency was also observed with the same condition. 相似文献
947.
Maria Ochsenkühn-Petropoulou Rachel Argyropoulou Klaus-Michael Ochsenkühn 《Mikrochimica acta》2000,135(3-4):139-146
The efficiency of the production of the high temperature superconducting powders Bi2Sr2CaCu2O8+x (BSCCO 2212) using the solid state reaction in one or two step processes under different thermal treatment was compared by
means of different modern analytical techniques. Through the same techniques the optimization of the production of the production
of Bi-2212 powder produced by the two step process, was achieved. X-ray diffraction analysis (XRD) and Raman spectroscopy
were used to characterize the products for their stoichiometry and phase-purity. The grain size of the powders was observed
by scanning electron microscopy (SEM), while their superconducting properties were tested by electrical DC-resistivity and
magnetic susceptibility measurements using a superconducting quantum interference device (SQUID). It resulted that the two
step process gives a high quality BSCCO 2212 superconducting powder with T
c = 85 K, in a shorter time and with a greater recovery rate than the one step process.
Received May 3, 1999. Revision April 27, 2000. 相似文献
948.
Determination of oxytetracycline and some impurities in plasma by non-aqueous capillary electrophoresis using solid-phase extraction 总被引:1,自引:0,他引:1
Summary The potential of a non-aqueous, capillary electrophoresis (NACE) system for separating oxytetracycline from three of its impurities—tetracycline,
4-epioxytetracycline and 4-epitetracycline—using UV detection has been studied. The running buffer was: 25 mM sodium acetate,
1 mM EDTA, methanesulfonic acid, pH 4, dissolved in MeOH-ACN (50∶50,v/v). The method was also used to determine these compounds in pig plasma. A solid-phase extraction (SPE) procedure as a clean-up
step has also developed. For this we tested Sep Pak C18, LiChrolut EN and OASIS cartridges. OASIS cartridges were best. Recoveries were 90–100% for all compounds except EOTC which
had a recovery of 74%. 相似文献
949.
We propose lattice Boltzmann method for the spiral waves. Using Chapman-Enskog expansion and multiscales technique, we obtain equilibrium distribution functions of the model. As an example, we simulate the Selkov reactions with scratching mark, i. e. using a scratching mark pacemaker, obtained one classical spiral waves. 相似文献
950.
Based on the modification of the radial pulsation equation
of an individual bubble, an effective medium method (EMM) is presented for
studying propagation of linear and nonlinear longitudinal acoustic waves
in viscoelastic medium permeated with air bubbles. A classical theory
developed previously by Gaunaurd (Gaunaurd GC and \"{U}berall H, {\em J.
Acoust. Soc. Am}., 1978; 63: 1699--1711) is employed to verify the EMM under linear approximation
by comparing the dynamic (i.e. frequency-dependent) effective parameters,
and an excellent agreement is obtained. The propagation of longitudinal
waves is hereby studied in detail. The results illustrate that the nonlinear
pulsation of bubbles serves as the source of second harmonic wave and the
sound energy has the tendency to be transferred to second harmonic wave.
Therefore the sound attenuation and acoustic nonlinearity of the
viscoelastic matrix are remarkably enhanced due to the system's resonance
induced by the existence of bubbles. 相似文献