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191.
192.
Dominique Simon Olivier Lafont Claude Combet Farnoux Marcel Miocque 《Journal of heterocyclic chemistry》1985,22(6):1551-1557
Reactivity of 2-susbituted chalcones against diaza binucleophiles (hydrazines, thiourea, guanidine) has been studied. Various heterocycles (pyrazoles, pyrazolines, pyrimidines) or substituted hydrazines were obtained. A general interpretation is given according to the substituent of the enone system, R, the nature of binucleophile and the medium. 相似文献
193.
194.
Dominique Faure Doris Lexa Jean-Michel Savéant 《Journal of Electroanalytical Chemistry》1982,140(2):269-284
The cyclic voltammetric study of vitamin B12r in DMSO shows the importance of the base-on/base-off reaction in the electrochemical reduction mechanism. Depending upon the flux of electrons flowing through the system. part of the base-on complex is reduced through prior opening of the nucleotide side-chain which gives rise to the more easily reduced DMSO-Co(II) complex. The quantitative analysis of the variations of the peak heights with the sweep rate allows the thermodynamic and kinetic characterization of the base-on/base-off reactions to be determined. DMSO thus appears as a stronger ligand toward Co(II) than water, leading to an increased participation of the base-off complex in the reduction process. The greater stability of the DMSO complex is also related to the observation that electron transfer is significantly slower than in the case of the water complex. The importance of the ligand exchange reactions in the reduction of B12r is confirmed by the effect of pyridine additions. Three complexes then participate in the reduction process, their reduction potentials lying in the order DMSO >Py >Bzm. The reduction mechanism involving the interconversion of the three complexes is described as a function of the electrode potential, the flux of electrons and the pyridine concentration. An estimation of the equilibrium and rate constants of the three ligand exchange reactions is made, based on the variations of the cyclic voltammograms with the sweep rate and the pyridine concentration. 相似文献
195.
196.
197.
Jacques Gilbert Dominique Rousselle Charles Gansser Claude Viel 《Journal of heterocyclic chemistry》1979,16(1):7-11
A new snythesis of 6H-pyrido[4,3-b]carbazoles is described starting from substituted cyclohexanones involving the combination of Borsche's carbazole preparation and Cranwell and Saxton's ellipticine synthesis where the starting materials are easily available. The dehydrogenation step is accomplished at an early stage. In some cases (11-desmethyl ellipticines derivatives), 7H-pyrido[3,4-c]carbazoles were also obtained. 相似文献
198.
Dominique Perrin 《Mathematische Zeitschrift》1977,153(3):283-287
Sans résumé 相似文献
199.
Lise Crevier-Buchman Ollivier Laccourreye Jean-François Papon Dominique Nurit Daniel Brasnu 《Journal of voice》1997,11(2):232-237
We analyzed frequency and duration parameters of voice and speech in two men with adductor spasmodic dysphonia (SD). One was treated with botulinum toxin injection; the other received acupuncture therapy. Im provement after acupuncture therapy in terms of standard deviation of fundamental frequency, acoustic perturbation measurements, durational measurements of voice and speech, and spectrographic analysis was comparable to the results achieved with botulinum toxin injection. Voice and speech parameters were stable I year after acupuncture therapy. 相似文献
200.
J.Pierre Moeglin Bemard Gautier René Joecklé Dominique Bolmont 《Optics and Lasers in Engineering》1997,28(5):317-330
A measurement of the electrical parameters degradation of Si photodiodes irradiated by laser visible light has been performed. The laser is a Q-switched Nd:YAG, frequency doubled, operated in single pulse mode of 4 ns duration. The applied fluence levels range up to 90 J/cm2. Two kinds of irradiation process were applied: either a part of the detector active area was irradiated in single pulse mode, or a scanning of the whole detector active area was performed with successive identical pulses. It has been shown that the fluence necessary to induce significant changes (local decrease of 35%) in responsivity is several times the surface melting threshold fluence (0.5 J/cm2). Conversely, the dark current is the most sensitive parameter, increasing by about four times for high irradiation. The in-depth dopant distribution is altered by high fluence irradiation in a way that cannot be explained by simple thermal modelling. 相似文献