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991.
992.
Hiroshi Watanabe 《Journal of statistical physics》1989,54(1-2):171-190
A block spin approach to the Euclidean
4 field theory in three dimensions is proposed by using the three-dimensional version of Gawedzki and Kupiainen's block spin transformation method. The lattice
3
4
model recovers the rotation invariance in the continuum limit, when the coupling constant is small. 相似文献
993.
Summary We applied Wiener's theory to calculate form birefringence dispersion of an oriented block copolymer from dispersion formulas of refractive indices of bulk polymers corresponding to the blocks forming the microdomains. The nearly perfect concordance of the measured birefringence dispersion with the calculated one seems to indicate an almost complete lack of molecular orientation inside microdomains. The importance of birefringence dispersion involves modification of interference spectrum in white light. This phenomenon may induce errors when ultilizing a Berek compensator for birefringence measurements.With 16 figures 相似文献
994.
Atsushi Takemura Akio Murai Hidetoshi Kawai Takanori Suzuki 《Tetrahedron letters》2004,45(41):7567-7571
A synthetic method for a branched ether system was developed. The method was based on Lewis-acid-promoted γ-position selective reduction of a γ-alkoxy β,γ-unsaturated α-silyloxy nitrile, prepared through a process including intermolecular hetero-Michael reaction of a 2-butynoate ester derivative with an alcohol. The method was efficiently applied to the synthesis of fused medium-ring ethers involving the EF-ring segment (2) of ciguatoxin (1). 相似文献
995.
Poly (oligoether methacrylate-co-acrylonitrile) s, P (MEOn- AN), with oligoether pendants of different lengths were synthesized and the ion conduction property of their Li-salt complexes was studied as the function of polymer structure. At proper copolymer composition, lithium concentration and pendant length, the ion conductivity reaches 7.0×10~(-5)S/cm at ambient temperature, together with improved mechanical strength. The ion transport in the polymer media is assisted by segmental relaxation, which is confirmed both by the consistency between ion conductivity and T_g and by the study of TSC. 相似文献
996.
Novel poly(vinyl-methylether)-b-poly(vinyloxy-4-butyric acid) diblock copolymers were made for the purpose of colloidal stabilization
of particles in liquids. The synthesis via cationic polymerization with HI/I2 initiation and the characterization of such novel diblock copolymers is described. A set of polymers was prepared including
block copolymers with different block length ratios and the two separate homopolymers having the chemical composition of one
of the blocks. Colloidal stabilization of α-Fe2O3 particles in water could be realized with all polymers except with the (vinylmethylether) homopolymer. One of the block copolymers
was used for evaluation of the stabilizing abilities in organic solvents. Stable α-Fe2O3 dispersions could be prepared in solvents with very different polarities, ranging from methanol to toluene. In addition,
it is shown that particles stabilized with these block copolymers can be easily transferred from water to an organic liquid.
Received: 15 May 1997 Accepted: 13 October 1997 相似文献
997.
Here we reported a novel and efficient method for the synthesis of the critical intermediates of branched fluorinated surfactants with CF3CF2CF2C (CF3)2- group using HFPD as starting material. The reaction conditions were mild and easy to handle, which was promisingly applied to the industrial production. 相似文献
998.
Toru TachiharaTakeshi Kitahara 《Tetrahedron》2003,59(10):1773-1780
Enantioselective total synthesis of (+)-epiepoformin 1, (+)-epiepoxydon 2 and (+)-bromoxone 3 using a chiral building block, ethyl (1R,2S)-5,5-ethylenedioxy-2-hydroxycyclo- hexanecarboxylate 6, is described. Since the synthesis afforded intermediates 18, 2 and 25, it accomplished a formal synthesis of (−)-theobroxide 19, (−)-phyllostine 22, (+)-herveynone 27 and (−)-asperpentyn 28. The usefulness of 6 for the synthesis of natural epoxycyclohexene derivatives was demonstrated. 相似文献
999.
Yasuhiko Haneda Hiroyuki Terada Michie Yoshida Akira Ueda Susumu Nagai 《Journal of polymer science. Part A, Polymer chemistry》1994,32(14):2641-2652
Various aliphatic polyesters such as poly (ethyleneadipate), poly (tetramethylene adipate), poly (caprolactone), and poly (carbonate) were condensed with 4,4'-azobis-4-cyanopentanoyl chloride to prepare macro-azo-initiators. Their thermal properties, observed by differential scanning calorimetry, showed similar decomposition behavior to each other. Block copolymers containing each of these polyesters as a block segment combined with polystyrene or poly (methylmethacrylate) have been derived by the polymerization of monomers initiated with these macro-azo-initiators. © 1994 John Wiley & Sons, Inc. 相似文献
1000.