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951.
Moiss M. Werlang Marco A. De Araújo Suzana P. Nunes I. Valria P. Yoshida 《Journal of Polymer Science.Polymer Physics》1997,35(16):2609-2616
Blends of organosilicon polymers with polystyrene, PS, and poly(2,6-dimethyl-1,4-phenylene oxide), PPE, were investigated by transmission electron microscopy and differencial scanning calorimetry. Blends with poly(tetramethylsilphenylenesiloxane), PTMPS, showed a morphology characterized by globular domains dispersed in the organic matrix. An apparent homogeneous system was observed when poly(dimethylsilphenylene), PDSP, was mixed with PPE. A crystalline phase was found in samples with a higher PDSP content. The morphology of PS/PDSP blends with low PDSP content showed a dendritic phase dispersed in the PS-rich matrix. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2609–2616, 1997 相似文献
952.
Yasuyuki Kita Kazuhiro Higuchi Yutaka Yoshida Kiyosei Iio Shinji Kitagaki Shuji Akai Hiromichi Fujioka 《Angewandte Chemie (International ed. in English)》1999,38(5):683-686
Seventeen years after the isolation of the promising antitumor antibiotic fredericamycin A, the first asymmetric total synthesis of this compound has been accomplished and thereby its absolute configuration established. The key feature is the regiocontrolled [4+2] cycloaddition of 3 to 2 , which was obtained by the stereospecific rearrangement of 1 . Cp = (−)‐camphanoyl. 相似文献
953.
954.
Masataka Nagaoka Naoto Yoshida Tokio Yamabe 《International journal of quantum chemistry》1996,60(1):287-295
The generalized Langevin equations are presented by considering such microscopic motions of molecules described by the microscopic Hamiltonian whose potential function is quadratic and internal degree of freedom is multidimensional. Considering the long time behavior of the reactive mode, the Grote-Hynes equation has been derived from the generalized Langevin equations. Furthermore, we have proved that solving the Grote-Hynes equation is equivalent to solving the eigenvalue problem for the whole system, and then the Grote-Hynes treatment coincides with the transition-state theory for the whole system. © 1996 John Wiley & Sons, Inc. 相似文献
955.
Tatsuhiro Yoshida Yoshiharu Abe Toshio Masuda Toshinobu Higashimura 《Journal of polymer science. Part A, Polymer chemistry》1996,34(11):2229-2236
(p-tert-Butyl-o,o-dimethylphenyl)acetylene (BDMPA) polymerized in high yields in the presence of W and Mo catalysts. Especially the W(CO)6–CCl4–hv catalyst quantitatively produced a polymer totally soluble in toluene and chloroform. The weight-average molecular weight of this polymer exceeded 2 × 106. Poly(BDMPA) was a dark brown solid, and had alternating double bonds along the main chain. The weight loss of the polymer in air occurred only above 300°C, indicating a fairly high thermal stability. A free-standing film could be fabricated by solution casting. The electrical conductivity of the polymer at 25°C was 1 × 10−13 S cm−1. The oxygen permeability coefficient and the separation factor of O2 vs. N2 of the polymer at 25°C were 67 barrers and 3.2, respectively. © 1996 John Wiley & Sons, Inc. 相似文献
956.
Tadatomi Nishikubo Atsushi Kameyama Youji Yamada Yuichi Yoshida 《Journal of polymer science. Part A, Polymer chemistry》1996,34(17):3531-3537
A convenient esterification reaction of poly(methacrylic acid) (PMAA) with certain alkyl halides was performed using 1,8-diazabicyclo-[5.4.0]-7-undecene (DBU) as a base in aqueous solution or in water. The esterification reaction of PMAA with propargyl bromide (PB) proceeded very smoothly and quantitatively at 30°C to give corresponding poly(propargyl methacrylate), although the rate of the reaction decreased with increasing water. The reaction of PMAA with benzyl bromide, o-nitrobenzyl bromide, and p-nitrobenzyl bromide gave corresponding poly(methacrylic ester) using DBU under suitable reaction conditions in water. The esterification reactions of PMAA with PB were carried out using certain organic bases such as triethylamine, 4(N,N-dimethylamino)pyridine and pyridine. Inorganic bases such as sodium carbonate, sodium hydroxide, potassium carbonate, and potassium hydroxide were also tried under the same conditions as with DBU. However, the degrees of estrification with all these bases was much lower than that with DBU. © 1996 John Wiley & Sons, Inc. 相似文献
957.
958.
T Hatano H Uebayashi H Ito S Shiota T Tsuchiya T Yoshida 《Chemical & pharmaceutical bulletin》1999,47(8):1121-1127
Thirteen phenolic glycosides including six new compounds were isolated from seeds of Cassia tora (Leguminosae). The structures of the new compounds, rubrofusarin triglucoside (7), nor-rubrofusarin gentiobioside (9), demethylflavasperone gentiobioside (10), torachrysone gentiobioside (11), torachrysone tetraglucoside (12) and torachrysone apioglucoside (13), were elucidated on the basis of spectroscopic and chemical evidence. The effects of the phenolic glycosides, their aglycones and several other compounds structurally related to them on Escherichia coli K12, Pseudomonas aeruginosa PAO1 and some strains of Staphylococcus aureus were then examined. Among them, torachrysone (15), toralactone (16), aloe-emodin (18), rhein (19) and emodin (20) showed noticeable antibacterial effects on four strains of methicillin-resistant Staphylococcus aureus with a minimum inhibitory concentration of 2-64 micrograms/ml. On the other hand, the phenolic compounds tested did not show strong antibacterial effects on E. coli and P. aeruginosa. 相似文献
959.
960.
Masao Tamada Masaharu Asano Reimar Spohr Johann Vetter Christine Trautmann Masaru Yoshida Ryouichi Katakai Hideki Omichi 《Macromolecular rapid communications》1995,16(1):47-51
The porous copolymer films of N-methacryloyl-L -alanine methyl ester and diethyleneglycol-bis-allylcarbonate (diallyl oxydiethylene dicarbonate) were hydrolyzed with 1 M NaOH solution for 40 min at 25°C. The pores of the films showed pH response in diameter. The pore diameter of 3,7 μm in the buffer solution of pH 3 was closed completely at pH 5. 相似文献