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21.
22.
Lionel Moisan Eric Doris Bernard Rousseau Pierre Thury 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(11):o792-o794
The title compounds are indole alkaloids of the Iboga class. In both compounds, viz. catharanthinol methanol solvate, C20H24N2O·CH4O, (I), and dihydrocatharanthinol monohydrate, C20H26N2O·H2O, (II), a nitrogen‐containing seven‐membered ring is fused to the indole system and shares two sides with a tricyclic isoquinuclidine group. The main difference between (I) and (II) is the presence of a C=C bond in the isoquinuclidine ring in (I). The presence of amine and hydroxy groups in these molecules and of methanol [in (I)] or water [in (II)] solvent molecules results in intra‐ and/or intermolecular hydrogen bonding. 相似文献
23.
Lionel Moisan Thierry Le Borgne Pierre Thury Michel Ephritikhine 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(2):m98-m101
In bis[1,1′,2,2′,3,3′,4,4′‐octamethyl‐5‐(2‐pyridinio)‐5′‐(2‐pyridyl)ferrocene] di‐μ3‐chloro‐hexadeca‐μ2‐chloro‐hexachlorodi‐μ4‐oxo‐di‐μ3‐oxo‐bis[(η5,κN)‐1,2,3,4‐tetramethyl‐5‐(2‐pyridyl)cyclopentadienyl]octauranium(IV) dichloromethane tetrasolvate, [Fe(C14H17N)(C14H16N)]2[U8Cl24O4(C14H16N)2]·4CH2Cl2, (I), two protonated Fe(cp*py)2 units [cp*py is tetramethyl‐5‐(2‐pyridyl)cyclopentadiene] form an ion pair with the dianionic centrosymmetric cluster U8Cl24O4(cp*py)2. The latter is the highest nuclearity assemblage in the chemistry of uranium (non‐uranyl) compounds reported to date. 相似文献
24.
This paper reports the evolution of phase transitions and ferroelectric properties of the pyrochlore type compound Cd2Nb2O7 by substitution of Cd2+ by other divalent cations and of oxygen by sulfur. This study shows the existence of ferroelectric phases at room temperature when the oxygen ions in Cd2Nb2O7 are partially replaced by sulfur ions. The ferroelectric behavior of CdZnNb2O6S above room temperature is reported. 相似文献
25.
J.Y. Moisan 《European Polymer Journal》1980,16(10):979-987
Chemical efficiency and stabilizer migration are the most important factors to be considered in connection with the ageing of polyethylene. This paper gives diffusion coefficients and solubilities for various industrial additives in low density polyethylene. The results, together with activation energies for diffusion, allow study of the diffusion process. It seems that it is necessary to consider deformations of the diffusing molecules and the polymer molecules. Additives of low molecular weight diffuse as gases, those of high molecular weight behave like polymer chains in self-diffusion. 相似文献
26.
27.
We consider a model for phase separation of a multi-componentalloy with a concentration-dependent mobility matrix and logarithmicfree energy. In particular we prove that there exists a uniquesolution for sufficiently smooth initial data. Further, we provean error bound for a fully practical piecewise linear finiteelement approximation in one and two space dimensions. Finallynumerical experiments with three components in one space dimensionare presented. 相似文献
28.
Traoré AS Godbout MJ Serre D Younan R Dionne G Dufour M Morin J Moisan C 《Magnetic resonance imaging》2003,21(6):609-615
The present study was undertaken to measure the gain observed in the liver-to-tumor contrast of perioperative images when using mangafodipir trisodium, a liver-specific contrast agent, during percutaneous cryosurgery of the liver performed under the guidance of magnetic resonance images. Retrospective quantitative analyses of MR images were performed on eleven patients having a total of 30 liver tumors treated by MR-guided percutaneous cryosurgery. An initial group of four patients were treated with no contrast agent, and was compared with a second group of 7 patients who received an intravenous injection of 5 microM/kg of mangafodipir for their cryosurgery. The percutaneous cryosurgery was monitored under the near-real-time-imaging mode of a 0.5T open-configuration MRI system using a T(1)-weighted Gradient-recalled echo pulse sequence. A significant improvement in the liver-to-tumor contrast-to-noise ratio was observed with mangafodipir (p < 0.05, paired t test) in 0.5T preoperative images. Along with the stability of the mangafodipir contrast enhancement during the entire cryosurgical procedure, the resulting gain in contrast allowed for better visualizing the presence of residual untreated tumor margins at the periphery of the cryosurgery iceball directly from perioperative images acquired with patients under narcosis. Consequently, it not only became easier for the interventionalist to determine the need for an additional cryoprobe to increase the size of the iceball during the procedure, but also to decide on the appropriate end point of the cryosurgery. 相似文献
29.
Trischuk W de Troconiz JF Tseng J Turini N Ukegawa F Vaiciulis T Valls J Vejcik S Velev G Vidal R Vilar R Volobouev I Vucinic D Wagner RG Wagner RL Wahl J Wallace NB Walsh AM Wang C Wang CH Wang MJ Watanabe T Waters D Watts T Webb R Wenzel H 《Physical review letters》2000,85(10):2062-2067
We use 106 pb (-1) of data collected with the Collider Detector at Fermilab to search for narrow-width, vector particles decaying to a top and an antitop quark. Model independent upper limits on the cross section for narrow, vector resonances decaying to t&tmacr; are presented. At the 95% confidence level, we exclude the existence of a leptophobic Z' boson in a model of top-color-assisted technicolor with mass M(Z')<480 GeV/c(2) for natural width gamma = 0.012M(Z'), and M(Z')<780 GeV/c(2) for gamma = 0.04M(Z'). 相似文献
30.
Tipton P Tkaczyk S Tollefson K Tollestrup A Toyoda H Trischuk W de Troconiz JF Tseng J Turini N Ukegawa F Vaiciulis T Valls J Vejcik III Velev G Vidal R Vilar R Volobouev I Vucinic D Wagner RG Wagner RL Wahl J Wallace NB Walsh AM Wang C Wang CH Wang MJ 《Physical review letters》2000,85(10):2056-2061
We report the results of a search for second and third generation leptoquarks using 88 pb(-1) of data recorded by the Collider Detector at Fermilab. Color triplet technipions, which play the role of scalar leptoquarks, are investigated due to their potential production in decays of strongly coupled color octet technirhos. Events with a signature of two heavy flavor jets and missing energy may indicate the decay of a second (third) generation leptoquark to a charm (bottom) quark and a neutrino. As the data are found to be consistent with standard model expectations, mass limits are determined. 相似文献