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1.
The oxidizing power of hexacyanoferrate(III) in alkaline conditions is wellknown. Unfortunately many if its oxidation reactions are too slow at room temperatures for direct titrimetric procedures. A method has been developed for the determination of millimolar amounts of selenium(IV), arsenic(III), antimony(III), chromium(III), and thallium(I) using thermometric titrimetry at approximately 330 K. The reproducibility and accuracy of the method are approximately 1%. 相似文献
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[reaction: see text] By using a sequence of regiocontrolled halogenation and palladium-catalyzed coupling reactions, the synthesis of variously substituted oxazoles from ethyl 2-chlorooxazole-4-carboxylate (2) was accomplished. The methodology was applied to the synthesis of a series of 2,4-disubstituted, 2,5-disubstituted, and 2,4,5-trisubstituted oxazoles. 相似文献
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L. S. Bark C. Bowmer L. Kershaw W. A. Moreno J. D. Openshaw 《Journal of Thermal Analysis and Calorimetry》1994,42(2-3):595-606
The advantages of using diodes as thermal sensors in solution thermochemistry are discussed and a simple, low-cost circuit for the use of diodes as temperature sensors is reported. In preliminary studies, the titration of TRIS and hydrochloric acid is used to compare the precision of thermistors and diodes in thermometric titrimetry. Several systems are assayed at various temperatures by enthalpimetric methods to illustrate the advantages of diodes as sensors for monitoring thermal methods capable of being used in quality control system. 相似文献
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G. N. Malcolm C. E. Baird G. R. Bruce K. G. Cheyne R. W. Kershaw M. C. Pratt 《Journal of Polymer Science.Polymer Physics》1969,7(9):1495-1511
Measurements are reported of the vapor pressures and the heats and volumes of mixing of solutions of poly(ethylene glycol dimethyl ether) in chloroform and in carbon tetrachloride. The measurements have been used to calculate the thermodynamic mixing functions for mixing with zero volume change. These values have been compared with the predictions of the lattice theory of mixtures at three different levels of approximation, viz., the generalized “first approximation” theory of Barker, the “zeroth approximation” theory, and the Flory theory. In the hydrogen-bonding chloroform solutions the Barker theory is more successful than the other forms of the lattice theory. The results have also been used, in conjunction with those for solutions of poly(propylene glycol dimethyl ether) in the same two solvents, to test the ability of the Barker theory to correlate the properties of related systems. Good correlation is found between the two carbon tetrachloride solutions but not between the chloroform solutions. It is probable that the side-chain methyl groups in the propylene oxide repeating unit cause the hydrogen-bonding interaction to be weaker in this polymer than it is in the polymer with the ethylene oxide repeating unit. 相似文献
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Measurements of synchrotron radiation emitted by 30-MeV runaway electrons in the TEXTOR-94 tokamak show that the runaway population decays after switching on neutral beam injection (NBI). The decay starts only with a significant delay, which decreases with increasing NBI heating power. This delay provides direct evidence of the energy dependence of runaway confinement, which is expected if magnetic modes govern the loss of runaways. Application of the theory by Mynick and Strachan [Phys. Fluids 24, 695 (1981)] yields estimates for the "mode width" (delta) of magnetic perturbations: delta<0.5 cm in Ohmic discharges, increasing to delta = 4.4 cm for 0. 6 MW NBI. 相似文献
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