Results 261 to 270 of about 21,548 (308)

Acid deuterium exchange in benzazoles

Chemistry of Heterocyclic Compounds, 1986
The kinetics of acid deuterium exchange in benzazoles carrying electron-donor substituents in the 5-, 6-, or 7-positions have been studied. Mass spectrometric studies have shown that exchange in 5-methoxy-1, 2-dimethylbenzimidazole takes place exclusively at one position in the benzene ring, in 5-chloro-, 7-chloro-,5-methoxy-2-methylbenzothiazole and 6-
I. F. Tupitsyn, N. N. Zatsepina, A. I. Belyashova, A. A. Kane   +3 more
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Weak acid ion exchange membranes

Die Angewandte Makromolekulare Chemie, 1989
AbstractWeak acid ion exchange membranes were prepared by pressing methyl acrylate/methyl methacrylate and methyl acrylate/butyl methacrylate copolymers into the film form. Before shaping, the copolymers were hydrolysed in an alkaline solution (heterogeneous system).
Aleksandra Gasperowicz, Gryzelda Poźniak, Witold Trochimczuk   +2 more
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Ion-exchange chromatographic analysis of peroxynitric acid

Journal of Chromatography A, 2016
Ion-exchange chromatographic analysis of peroxynitric acid (O2NOOH) was performed by combining an acidic eluate with an UV-vis detector and immersing the separation column in an ice-water bath. The decomposition behavior of peroxynitric acid in the solution was also studied using this system.
Yoichi Nakashima, Satoshi Ikawa, Atsushi Tani, Katsuhisa Kitano   +3 more
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Exchange reactions and phosphoglyceric acid in photosynthesis

Archives of Biochemistry and Biophysics, 1952
Abstract Experiments have been described in which total fixation of carbon dioxide in short periods of photosynthesis has been studied simultaneously with the fixation in the carboxyl of phosphoglyceric acid. These kinetic studies have shown that the labeling of phosphoglyceric acid represents a step in the photosynthetic process and is not due to an
E W, FAGER, J L, ROSENBERG
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Exchange diffusion in acid-filled gastric pouches

Journal of Surgical Research, 1969
Abstract The reduction of acidity in acid-filled innervated and denervated canine, gastric pouches increased with increasing concentrations of HCl within the lumen. This increasing acidity reduction occurred without an increase in volume, which could be attributed to a non-parietal alkaline secretion entering the lumen.
G K, Wlodek, L, Greenberg, R, Lajzerowicz   +2 more
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Deuterium exchange in arsenobetaine and dimethylarsinoylacetic acid

Journal of Inorganic Biochemistry, 2005
Arsenobetaine occurs naturally in almost all marine animals and it is assumed to be the unreactive end-product of a detoxification pathway. To investigate the properties of arsenobetaine and its likely immediate biogenic precursor, dimethylarsinoylacetic acid, we studied the exchanges of the C-2 methylene protons of these compounds in D2O solution and ...
John S, Edmonds, Makoto, Nomachi, Masatoshi, Morita   +2 more
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Cation-exchange in thiourea-hydrochloric acid solutions

Talanta, 1983
Ion-exchange distribution coefficients are reported for several transition and post-transition elements in solutions of hydrochloric acid (0.1-3.0M) and thiourea on AG50W resins. Some typical elution curves illustrate use of the systems with special reference to the separation of small amounts of gold, palladium, platinum, rhodium and iridium from ...
C H, -Siegfried, W, Weinert, F W, Strelow, R G, Böhmer   +3 more
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Ion-Exchange Equilibria of Amino Acids on a Strong Acid Resin

Industrial & Engineering Chemistry Research, 1996
The exchange equilibria of several amino acids, with particular emphasis on those displaying two basic groups, on a strong-acid cation exchange resin (Amberlite IR120) are investigated. The behavior of the experimental data is described through a mathematical model which takes into account the dissociation equilibria of amino acids in aqueous solution,
S. Melis, J. Markos, G. Cao, MORBIDELLI, MASSIMO   +3 more
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Acid exchange resins deactivation in the esterification of free fatty acids

Chemical Engineering Journal, 2010
In this work the deactivation of an ionic exchange resin, used as catalyst for promoting the esterification of fatty acids for producing biodiesel, has been studied. At this purpose, a dynamic mathematical model, suitable to describe the performances of a continuous tubular reactor containing the catalysts mixed with stainless steel springs as inert ...
TESSER, RICCARDO, SANTACESARIA, ELIO, DI SERIO, MARTINO, L. Casale, M. Ledda, L. Sannino   +5 more
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THE ISOTOPIC EXCHANGE OF FLUOROBORIC ACID WITH HYDROFLUORIC ACID

The Journal of Physical Chemistry, 1960
The isotopic exchange rate of fluorine between fluoroboric and hydrofluoric acids was investigated. The rate of exchange R = 4.5 x 10/sup -4/ e/ sup -24//sup .70//sup 0// /sup RT/ STABF/sup -//sub 4/!STAH/sup +/! liters mole/ sup -1/ sec/sup -1/. The exchange was found to proceed via HBF/sub 4/ = HF + BF/ sub 3/.
M. Anbar, S. Guttmann
openaire   +1 more source