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101.
102.
In 1949 Dirac published a paper in which he proposed various ways to combine special relativity with the Hamiltonian formulation of dynamics; these were referred toas forms and three differentforms, theinstant, thepoint, and thefront forms, were discussed. Dirac considered thefront form to be mathematically the most interesting. Despite this, thefront form appears to have been the least explored. This paper presents the results of a study of quantum mechanics in thefront form. 相似文献
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The thermal reaction of HNCO with NO2 has been studied in the temperature range of 623 to 773 K by FTIR spectrometry. Major products measured are CO2 and NO with a small amount of N2O. Kinetic modeling of the time resolved concentration profiles of the reactants and products, aided by the thermochemical data of various likely reactive intermediates computed by means of the BAC-MP4 method, allows us to conclude that the reaction is initiated exclusively by a new bimolecular process: with a rate constant, k1 = 2.5 × 1012e?13,100/T cm3/mols. The well-known bimolecular reaction is the only strong competitive process in this important reactive system throughout the temperature range studied. Kinetic modeling of NO formation and NO2 decay rates gave rise to values of k10 which were in close agreement with literature data. © 1993 John Wiley & Sons, Inc. 相似文献
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107.
S. D. Pollington M. S. Ioffe M. Westergaard J. K. S. Wan 《Research on Chemical Intermediates》1995,21(1):59-68
A high-power microsecond pulsed microwave system operating in the X-band region was used for the catalytic conversion of methane. Microwave microsecond pulses at repetition rates of 50 and 80 Hz were used to initiate chemical reactions. The Microwave-Induced Acoustic technique was employed in combination with gas chromatography for on-line detection of chemical products. Methane was converted to C2 and C3 hydrocarbons. The selectivity of ethane in hydrocarbon products can be >90 %. The contribution of hydrogen evolution and carbon deposition has been shown to be important. A comparison between previous experiments performed with millisecond pulse durations is given. 相似文献
108.
Visible light induced photocatalytic reaction of rhodamine B dye via 12-tungstosilicic acid in water
Using 12-tungstosilicic acid (SiW124-) as the catalyst, rhodamine B (RhB) dye in an aerated aqueous solution can undergo an effective photocatalytic stepwise N-deethylation process under visible light irradiation, and dioxygen is reduced to hydrogen peroxide by the reducedSiW12 4-. This provides the potential for moving polyoxometalate-based photocatalytic processes from the near-UV into the visible region of the spectrum. 相似文献
109.
Cai H Chen T Wang X Schultz AJ Koetzle TF Xue Z 《Chemical communications (Cambridge, England)》2002,(3):230-231
Reactions of Ta(NMe2)5 with D2SiR'Ph (R' = Me, Ph) were found to give a dideuteride eta 2-imine complex (Me2N)3Ta(mu-D)2(mu-N-eta 2-N,C-CH2NMe)Ta(NMe2)3(1-d2) through C-H activation of an amide ligand via beta-H abstraction, and the structure of 1 was confirmed by single crystal neutron and X-ray diffraction. 相似文献
110.
Cecilia Wan Ying Chung 《Tetrahedron》2005,61(3):709-715
An insoluble polystyrene-supported triflating reagent has been prepared by suspension co-polymerization of N-(4-vinylphenyl)trifluoromethanesulphonimide, styrene and the JandaJel® cross-linker. This reagent, in the presence of triethylamine, allows for the efficient synthesis of aryl triflates from a wide range of phenols in a process that permits the desired product to be isolated from the reaction mixture in essentially pure form via several filtration and concentration operations. Adding to the utility of this reagent is its ability to be easily recovered, regenerated and reused. Both soluble and insoluble bifunctional polymers containing trialkylamine moieties in addition to triflimide groups were also prepared and examined as triflating reagents. Unfortunately these reagents afforded only modest yields of the desired products in representative reactions. 相似文献