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In this paper, we define a class of extended quantum enveloping algebras U q (f(K, J)) and some new Hopf algebras, which are certain extensions of quantum enveloping algebras by a Hopf algebra H. This construction generalizes some well-known extensions of quantum enveloping algebras by a Hopf algebra and provides a large of new noncommutative and noncocommutative Hopf algebras. 相似文献
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66.
Kajsa Stridsberg Ann‐Christine Albertsson 《Journal of polymer science. Part A, Polymer chemistry》2000,38(10):1774-1784
Novel elastomeric A‐B‐A triblock copolymers were successfully synthesized in a new two‐step process: controlled ring‐opening polymerization of the cyclic ether–ester 1,5‐dioxepan‐2‐one as the amorphous middle block (B‐block) followed by addition and polymerization of the two semicrystalline L ‐lactide blocks (A‐block). A 1,1,6,6‐tetra‐n‐butyl‐1,6‐distanna‐2,5,7,10‐tetraoxacyclodecane initiator system was utilized and the reaction was performed in chloroform at 60 °C. A good control of the synthesis was obtained, resulting in well defined triblock copolymers. The molecular weight and chemical composition were easily adjusted by the monomer‐to‐initiator ratio. The triblock copolymers formed exhibited semicrystallinity up to a content of 1,5‐dioxepan‐2‐one as high as 89% as determined by differential scanning calorimetry. WAXS investigation of the triblock copolymers showed a crystal structure similar to that of the pure poly(L ‐lactide). © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1774–1784, 2000 相似文献
67.
William H. Watson Guanmin Wu Michael G. Richmond 《Journal of chemical crystallography》2004,34(9):621-625
The reaction of p-toluidine with 2,3-dichloromaleic anhydride in the presence of added 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) does not give the known compound 2-chloro-3-p-toluidino-N-p-tolylmaleimide (1), but rather 2-p-toluidino-N-p-tolylmaleimide (2) in low yields. Repeating this same reaction with Et3N, pyridine, tmeda, and 4-Me2Npyridine in place of DBU furnishes the expected product 2-chloro-3-p-toluidino-N-p-tolylmaleimide, without the presence of 2-p-toluidino-N-p-tolylmaleimide. The participation of DBU in the chlorine for hydrogen exchange reaction in compound 1 has been demonstrated from the independent thermolysis reaction of 1 with DBU in toluene, where 2 was obtained as the sole isolable product. Compound 2 was isolated and fully characterized in solution, and the molecular structure was established by X-ray diffraction analysis. 2-p-Toluidino-N-p-tolylmaleimide crystallizes in the monoclinic space C2/c, a = 33.630(5), b = 12.508(2), c = 7.381(1), = 90.668(3), V = 3104.3(8)3, Z = 8, and D
calc = 1.251 Mg/m3; R = 0.0357, R
w = 0.0896 for 2011 reflections with I > 2(I). 相似文献
68.
Effects of Salt on the Orientational Order in Decylammonium Chloride/Ammonium Chloride/Water Systems
The effect of NH4Cl on the temperature dependence of deuterium oxide splitting (water order) and proton line width (surfactant order) in decylammonium chloride (DACl), D2O systems is reported. The molar ratio of DACl to D2O was held constant at .085 and the molar ratio of NH4Cl to D2O was varied from .012 to .029. We find for the above concentration ranges that in the nematic range the relative temperature dependence of the D2O splitting is little affected by changes on salt concentration. The slopes of the proton line widths as a function of temperature decrease with increasing salt concentration. The results are compared with earlier data on salt effects on order obtained with the disodium cromoglycate system. 相似文献
69.
Abstract Electronic states in junctions of nanotubes with different circumferences are studied in an effective-mass approximation. The junction is characterized by boundary conditions which mix wave functions associated with K and K′ points. At ε=0, they decay linearly with the distance from the thicker nanotube, showing that the conductance decays with the junction length in proportion to its third power. 相似文献
70.
Simon G. Bott Kaiyuan Yang Michael G. Richmond 《Journal of chemical crystallography》2003,33(7):585-588
The structure of (5S)-3,4-dichloro-5-menthoxy-2(5H)-furanone is reported. The title compound crystallizes in the monoclinic space group P21: a = 6.650(2) Å, b = 8.038(3) Å, c = 14.858(8) Å, = 97.01(3), V = 788.3(6) Å3, Z = 2, R = 0.0718, R
w = 0.0795 for 735 observed reflections with I > 3 (I), and the absolute configuration at C-5 of the furanone ring is shown to be (S). 相似文献