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541.
Jean-Bernard Regnouf De Vains Roger Lamartine Bernard Fenet Claude Bavoux Alain Thozet Monique Perrin 《Helvetica chimica acta》1995,78(6):1607-1619
The hetero-armed p(tert-butyl)calix[4]arene 1 was synthesized by a stepwise procedure. This ligand presented a very strong complexing behavior towards Cu1, giving the chiral complex 2 and parent species when reacted with CuII salts. High-resolution NMR techniques were employed for the characterization of 2 , demonstrating notably exchange processes between its two enantiomeric forms. The racemic nature of 2 was confirmed by X-ray crystal-structure analysis. 相似文献
542.
543.
Monique Laurent 《Discrete Mathematics》1996,150(1-3):257-279
Let X be a set of vectors in Rm. X is said to be a Hilbert base if every vector in Rm which can be written both as a linear combination of members of X with nonnegative coefficients and as a linear combination with integer coefficients can also be written as a linear combination with nonnegative integer coefficients. Denote by H the collection of the graphs whose family of cuts is a Hilbert base. It is known that K5 and graphs with no K5-minor belong to H and that K6 does not belong to H. We show that every proper subgraph of K6 belongs to H and that every graph from H does not have K6 as a minor. We also study how the class H behaves under several operations. 相似文献
544.
Emanuel C. Pollacco Claude Volant Yves Cassagnou Monique Conjeaud Roland Dayras Samuel Harar Robert Legrain Jean -Etienne Sauvestre 《Zeitschrift für Physik A Hadrons and Nuclei》1993,346(1):63-68
Recoil velocities of heavy residues produced in the bombardment of84Kr beams on a232Th target at energies about the Fermi velocity were determined using the method of correlations between fission fragments. The masses of both fragments were also measured. The data show events with high recoil velocity which are produced in incomplete fusion processes. Estimates of the energy transfer are given. Comparisons with incomplete fusion data obtained with other projectiles in the same incident velocity range show an increase of the energy transfer with the mass of the projectile. 相似文献
545.
A table is presented of various sequences of 3-valent convex polyhedra, a sequence being defined by p3p4???pi??? where pi is the number of faces with i edges. These sequences are given for polyhedra with 6, 7, 8, 9, 10 faces and the sequences where p3=0 are given for polyhedra having 11, 12, 13, 14 faces. The number of polyhedra is also given for each sequence. 相似文献
546.
The aim of this paper is to derive the Zakai equation associated with nonlinear filtering problems when the observation process is discontinuous and takes its values in a Riemannian symmetric space. The main tools are the stochastic development and the horizontal lift of manifold–valued càdlàg semimartingales 相似文献
547.
WIM Goettsch Johan Garssen Monique H. Hurks † Frank R. De Gruijl Henk Van Loveren 《Photochemistry and photobiology》1994,60(4):373-379
Abstract In this study lymphocytes from blood and/or spleen of different species (rat, mouse, human) were exposed to different doses of ultraviolet radiation (UVR). The functional activity of these lymphocytes was determined using assays for mitogen proliferation and the mixed lymphocyte response (MLR). These experiments demonstrated that in vitro exposure to UVR causes a dose-dependent decrease of the MLR activity of the irradiated lymphocytes. Viability of lymphocytes and mitogen proliferation responses were also decreased by UVR exposure but less severe in comparison to the MLR. Lymphocytes of rats seem to be more sensitive to UVR as compared to lymphocytes of mice and humans. 相似文献
548.
Monique Galin 《European Polymer Journal》1983,19(1):1-4
Study of the system poly(ethylene oxide) by gas-solid chromatography leads to two main conclusions: adsorption of the probe at the various interfaces is never negligible, in spite of the lack of any strong specific interaction between the alkane and the polyether. Reliable values of the degree of crystallinity may be however derived from measurements, taking into account these adsorption phenomena. The sharp increases of the specific retention volumes (Vg0) observed at well defined temperatures (about 42.3 and 51.4°C) are directly related to the well known chain unfolding ν4 → 3 and ν3 → 2 in the crystalline lamellae. 相似文献
549.
Jean-Christophe Schrotter Antonio Cardenas Monique Smaihi Nadine Hovnanian 《Journal of Sol-Gel Science and Technology》1995,4(3):195-204
Sol-gel synthesis of mixtures of tetraethoxysilane and a phosphorus alkoxide [P(OEt)3 or (OEt)2P-O-P(OEt)2 or PO(OEt)3] have been studied by 1H, 13C29Si and 31P liquid and solid state NMR, infrared and raman spectroscopies. This study shows different behaviors towards hydrolysis for these three different phosphates and phosphites. P(OEt)3 almost instantly reacts with water to form an intermediate species HPO(OEt)2, which slowly evolves first to HPO(OH)(OEt), then to HPO(OH)2 a few days later. For (OEt)2P-O-P(OEt)2, the P-O-P bond is broken when water is added, then the same intermediates are formed faster. PO(OEt)3 is hydrolyzed much slower than the other alkyl phosphates. After ten months, triethoxyphosphate is quantitatively present in the sol with little PO(OH)(OEt)2 species. All these hydrolyzed species are well characterized. Only the system which contains the tetraethoxysilane and the triethoxyphosphite P(OEt)3 forms a few P-O-P and P-O-Si bonds in the gel. Hydrolysis of tetraethoxysilane is much faster than that of phosphorus alkoxides and the conventional Q2, Q3 and Q4 condensed silicon species form the gel three dimensional network. 相似文献
550.
Pierre Thuéry Nelly Keller Monique Lange Julien -Daniel Vigner Martine Nierlich 《Journal of inclusion phenomena and macrocyclic chemistry》1994,20(4):373-379
p-tert-Butylcalix[6]arene forms a complex with 1.5 acetonitrile molecules, that are included in the macrocycle cavity. This complex crystallizes in the monoclinic system: space groupP21/m,a=14.043(4),b=16.916(11),c=14.199(11) Å,=98.27(6)°,V=3338(4) Å3,Z=2 (formula units). Refinement led to a final conventionalR value of 0.113 for 1654 reflections. Thepinched cone conformation of the calixarene is the same as that of the neutral and freeR-calix[6]arene already described. The two acetonitrile molecules interact with some phenyl ring -clouds, a methylene bridge and sometert-butyl groups of the calixarene.
Supplementary Data relating to this article (atomic coordinates for hydrogen atoms, anisotropic displacement parameters, selected geometrical parameters and observed and calculated structure factors) are deposited with the British Library as Supplementary Publication No. SUP 82188 (16 pages). 相似文献