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131.
《Mendeleev Communications》2020,30(5):615-617
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132.
133.
Ha H. Nguyen James H. McAliley David A. Bruce 《Journal of polymer science. Part A, Polymer chemistry》2012,50(10):2019-2028
Two novel water‐soluble meta‐poly(phenylene ethynylene) (mPPE) copolymers were synthesized and characterized, each contained ester and amine functional groups attached to exohelix positions on the phenylene rings and one contained methoxy endohelix functional groups. Secondary structure formation was investigated for these materials in aqueous solutions using ultraviolet and fluorescence spectroscopy. Additionally, the folding behaviors are reported for the mPPEs and their protected amine precursors in other protic and aprotic solvents. Results indicate that both mPPEs are able to form stable helical structures in water, while only the nonmethoxylated polymer exhibited a helical structure in acetonitrile and several alcohols. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
134.
《Analytical letters》2012,45(17):3280-3289
Abstract Herein, acetylene black (AB) was easily dispersed into water in the presence of dihexadecyl hydrogen phosphate (DHP), resulting in a stable and homogeneous AB‐DHP suspension. Then, an AB‐DHP composite film coated glassy carbon electrode (GCE) was constructed after evaporation of water. The electrochemical behavior of bisphenol A was investigated using cyclic voltammetry (CV), linear sweep voltammetry (LSV), and differential pulse voltammetry (DPV). Compared with the unmodified GCE, the AB‐DHP film‐modified GCE not only significantly enhances the oxidation peak current of bisphenol A but also lowers the oxidation overpotential, suggesting that AB‐DHP film‐modified GCE has great potential in sensitive determination of bisphenol A. Based on this, a sensitive and simple electrochemical method was developed after optimization of the experimental parameters such as supporting electrolyte, the amount of AB‐DHP, scan rate, and accumulation time. The linearity is over the range form 2.0×10?8 to 5.0×10?6 mol l?1, and the detection limit is 6.0×10?9 mol l?1. Finally, this method was successfully employed to determine bisphenol A in waste water samples. 相似文献
135.
The first total synthesis of the natural product (+)-oploxyne B is achieved. The synthesis has led to the confirmation of absolute stereochemistry of the natural product. The natural product displayed cytotoxic activity with IC50 values varying from 16 to 53 μM in four cancer cell lines tested. 相似文献
136.
Satoshi Ogawa Mieko Kikuchi Yasushi Kawai Ryu Sato 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):433-434
Abstract Novel stable benzodithiolium salts have been synthesized and characterized by X-ray crystallographic analysis, which have been readily converted to the first isolable dithiolyl radicals by one-electron reduction. 相似文献
137.
利用超声波制备了SnCl2-ZnCl2/C无汞乙炔氢氯化催化剂,同时加入稀土化合物以稳定催化剂的性能。通过黄金分割法与抛物线法确定了活性组分SnCl2与ZnCl2的最优质量比为2∶1。优选制备工艺,发现在反应温度140℃,乙炔空速300 h-1,V(HCl)/V(C2H2)=1.10时,由0.67 g SnCl2、0.33 g ZnCl2、0.05 g Tb4O7以及4 g焙烧过的活性炭组成的催化剂,其乙炔平均转化率最高,为67.70%。实验表明,载体的处理方式是影响催化剂性能的重要因素。 相似文献
138.
139.
Five novel tetrafluorinated biphenyl acetylene molecules containing two chiral centres in the side chain were synthesized. The mesomorphic behaviour of these compounds was characterized by differiential scanning calorimetry (DSC) and optical polarizing microscopy. All these compounds exhibit cholesteric and blue phases. 相似文献
140.
Tsutomu Takeichi Akiko Kobayashi Yuzi Takayama 《Journal of polymer science. Part A, Polymer chemistry》1992,30(12):2645-2652
Aromatic oligoamides of DP = 5 and 11 that have all meta-phenylene linkages were prepared by controlling the ratio of isophthaloyl chloride and diamines [m-phenylenediamine and bis(3-aminophenyl)acetylene], and then end-capped with aniline or 2-aminobiphenylene. Aromatic oligoamides having para-phenylene linkages were also prepared similarly using terephthaloyl chloride as a monomer. The oligoamides that have all m-phenylene linkages were soluble in organic solvents such as N-methyl-2-pyrrolidone and N,N-dimethylacetamide, though the oligoamides having p-phenylene linkages were much less soluble. The oligoamides having acetylene units in the backbone showed exotherm due to crosslinking. The onset of the exotherm appeared at 310-340°C for the oligoamides having all m-phenylene linkages, and 330-370°C for the oligoamides having p-phenylene linkages. They were melt-processed at 350 or 380°C for 1 h, giving tough and insoluble films from oligoamides having all m-phenylene linkages and brittle films from oligoamides having p-phenylene linkages. The films showed excellent thermal properties. For example, viscoelastic analyses showed little decrease of mechanical property up to 370°C, and Tg was not observed below the temperature. Thermogravimetric analyses also showed that thermal stability of the melt-processed films were excellent. © 1992 John Wiley & Sons, Inc. 相似文献