نتایج جستجو برای: catalytic effect
تعداد نتایج: 1710805 فیلتر نتایج به سال:
The effect of physiological concentrations of caffeine (purified from Persian tea) on adenosine deaminase (ADA) activity at physiological and pathological concentrations of adenosine (as substrate) in 50 mM Tris-HCl buffer (pH 7.3) at 37°C was investigated, using UV-VIS spectroscopy. ADA exhibited a bi-phasic activity behavior and both phases showed positive cooperativities indicating adenosine...
alkali and alkaline earth metals hydrogen sulfate catalyzed the one-pot three component condensation reactions of aldehydes, 1,3-dicarbonyl compounds and urea or thiourea under solvent-free conditions leading to 3,4-dihydropyrimidin-2(1h)-ones in high yields at 80 °c. our results showed that biginelli reaction not only is ph dependent, but the cation of catalyst plays an important role.
This review presents the synergistic effect in the catalytic system of ionic liquids (ILs) for the synthesis of cyclic carbonate from carbon dioxide and epoxide. The emphasis of this review is on three aspects: the catalytic system of metal-based ionic liquids, the catalytic system of hydrogen bond-promoted ionic liquids and supported ionic liquids. Metal and ionic liquids show a synergistic ef...
The effect of physiological concentrations of caffeine (purified from Persian tea) on adenosine deaminase (ADA) activity at physiological and pathological concentrations of adenosine (as substrate) in 50 mM Tris-HCl buffer (pH 7.3) at 37°C was investigated, using UV-VIS spectroscopy. ADA exhibited a bi-phasic activity behavior and both phases showed positive cooperativities indicating adenosine...
h-zsm-5 nano-zeolites were synthesized by hydrothermal method using tetrapropylammonium hydroxide (tpaoh) as a template in the presence of various tpabr concentrations. the effect of different tpabr/tpaoh molar ratios was studied on the catalytic performance of dehydration of methanol to dimethyl ether (dme) in a fixed bed reactor under the same operating conditions (t=300°c, p=1 atm, and whsv=...
A kinetic-spectrophotometric procedure is reported for determination of trace amounts of Ag(I). This method is based on catalytic effect of silver ion on the oxidation of congo red by potassium peroxodisulphate at pH=3.4 and 30 oC in the presence of 1,10-phenanthroline as an activator. The reaction was followed spectrophotometrically by measuring the rate of change in absorbance ...
a kinetic-spectrophotometric procedure is reported for determination of trace amounts of ag(i). this method is based on catalytic effect of silver ion on the oxidation of congo red by potassium peroxodisulphate at ph=3.4 and 30 oc in the presence of 1,10-phenanthroline as an activator. the reaction was followed spectrophotometrically by measuring the rate of change in absorbance of congo red at...
Backgrounds and Objectives: Volatile organic compounds (VOCs) are one of the common groups of contaminants encountered in the industrial activities, emitted through air stream into the atmosphere. To prevent the human and environmental health from the adverse effects of VOCs, air streams containing VOCs need to be treated before discharging to environment. This study was aimed at investigating ...
In a plasma source development of a hydrogen pair-ion plasma consisting of only hydrogen atomic ions, H and H−, efficient production of the atomic ions is required. Hydrogen positive ions produced in a PIG discharge are supplied to a catalyst. The ions are converted to the atomic ions on the catalyst surface, and an ionic plasma with very low electron density is generated.
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