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991.
Helene Lavayssiere Jacques Satge Jacques Barrau Moussa Traore 《Journal of organometallic chemistry》1982,240(4):335-348
A new aspect of the reactivity of germanones and germathiones towards nitrilimines, nitriloxides and nitrones is investigated. The regioselectivity of the dipolar 1,3-cycloaddition reactions between germanones or germathiones and diphenylnitrilimine is discussed.
The structure of the adducts is determined from chemical or spectroscopic studies (13C NMR, IR).
Germa-oxa- or -thia-diazolines, germaoxathiazoles and germaoxathiazolidines are obtained and the thermal stability of these adducts reported. 相似文献
992.
Gel permeation chromatography of water-soluble polymers, with special attention to polyelectrolytes, has been studied. A three-detector system (refractometry, conductimetry, viscometry) is used to characterize the polymers. A single curve is obtained for the calibration of the set of columns taking into account the hydrodynamic volume of the solutes and using a 0.1 N salt solution as the eluent to screen electrostatic forces. The role of the low adsorption of dextran on silica gel is pointed out. The dependence of elution volume on polymer concentration is demonstrated and interpreted in terms of the screening length of the molecules. 相似文献
993.
994.
The temperature dependences of g-factor and linewidth of C11,3NiCl2,13 single crystals have been measured from 10 to 400 K. The data indicate that nickel ions in graphite behave at low temperatures like Ising ions, with a phase transition occurring at about 30 K. 相似文献
995.
Jean-Pierre Crouzeix Jacques A. Ferland Siegfried Schaible 《Mathematical Programming》1983,27(3):342-354
We consider a generalization of a linear fractional program where the maximum of finitely many linear ratios is to be minimized subject to linear constraints. For this Min-Max problem, a dual in the form of a Max-Min problem is introduced and duality relations are established. 相似文献
996.
The migratory aptitude of the ethoxycarbonyl group in the pinacol rearrangement was deduced from the structure of the products observed after treatment of 2-substituted 2,3-dihydroxy-3-phenylbutyrates with fluorosulfonic acid at 0° for 3 minutes. The migratory aptitude of ethoxycarbonyl is comparable to that of ethyl, greater than that of methyl or hydrogen, but smaller than that of phenyl. Cyclization and fragmentation reactions were also observed. 相似文献
997.
998.
The absolute configuration of tri-o-thymotide was obtained from the crystal structure of the solvate with (R)-2-butanol in association with optical measurements. 相似文献
999.
Jacques Gapaillard 《manuscripta mathematica》1974,12(4):351-386
In this paper, the classical theory, due to R. de POSSEL [11][12], of abstract derivation basis with VITALI properties, is systematically generalized with a functional formulation. That is to say that the derivation by means of suitable families of measurable sets is replaced by a derivation using measurable functions. A theorem which gives various caracterizations of that functional basis of weak VITALI type includes a theorem obtained by R. de POSSEL [13] about this kind of derivation. This result leads to the introduction of VITALI conditions of functional type in a derivation theorem of N. DUNFORD and J. T. SCHWARTZ [3]. 相似文献
1000.
Jacques Dagaut Pierre Dizabo Alain Pompon Joelle Fillaux 《Journal of mass spectrometry : JMS》1975,10(10):905-912
Three fragmentations (loss of phenyl, hydrogen and a RCO radical) of benzocyclobutene derivatives of differently substituted 1,4-benzodioxin were studied. In some cases these molecules, deuteriated in a specific position, revealed the existence of several isomers of the molecular ion. 相似文献