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我国股市是“边缘化”还是“显现化”
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作者 贺强 《珠江经济》 2003年第12期90-91,共2页
目前,在新闻媒体及学术界流行着一个时髦的术语,即边缘化。这一术语不胫而走,被广泛运用到在发展中存在问题的各个领域。
关键词 中国 股票市场 “边缘化” “显现化” 经济分析 市场监管
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Microstructure characteristics and liquation behavior of fiber laser welded joints of Mg-5Zn-1Mn-0.6Sn alloy sheets 被引量:1
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作者 Qing-yuan SHE Hong-ge YAN +4 位作者 Ji-hua CHEN Bin SU Zhao-hui YU Chao CHEN Wei-jun XIA 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2017年第4期812-819,共8页
Fine-grained Mg?5Zn?1Mn?0.6Sn alloy sheets of2mm in thickness were welded by fiber laser welding.The appearanceand microstructures of the welding joints and liquation behaviors in the partially melted zone(PMZ)were in... Fine-grained Mg?5Zn?1Mn?0.6Sn alloy sheets of2mm in thickness were welded by fiber laser welding.The appearanceand microstructures of the welding joints and liquation behaviors in the partially melted zone(PMZ)were investigated.The resultsshow that,with the lower welding power and higher welding speed,the width and depth of the joints decrease.Moreover,some poresare detected at a very high welding speed.There are two kinds of liquation phenomena in the PMZ.One is the liquation networkalong grain boundaries associated with the liquation of substrate and segregation-induced liquation,the other is the molten poolinvolved with the liquation of the residual second phases at the boundaries.However,the liquation of substrate and thesegregation-induced liquation are the main liquation mechanism in the PMZ. 展开更多
关键词 magnesium alloy sheet fiber laser welding MICROSTRUCTURE liquation phenomenon liquation mechanism
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Solvent and Temperature Effects on Spectral Properties of Two Poly(3-alkyl)thiophene Derivatives
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作者 GAOChao WUHong-cai +2 位作者 YIWen-hui ZHANGQing-xue DONGFa-xin 《Semiconductor Photonics and Technology》 CAS 2005年第1期40-45,51,共7页
Two alkyl substituted polythiophene derivatives: poly(3-hexylthiophene)(P3HT) and poly(3-decylthiophene)(P3DT), have synthesized by oxidation coupling polymerization of 3-alkylthiophene using iron(III) chloride as cat... Two alkyl substituted polythiophene derivatives: poly(3-hexylthiophene)(P3HT) and poly(3-decylthiophene)(P3DT), have synthesized by oxidation coupling polymerization of 3-alkylthiophene using iron(III) chloride as catalyst in chloroform. While both polymers in pure chloroform solution have maximum absorption at approximately same wavelength of 440nm, they behave differently with respect to changes observed on their UV-visible and photoluminescence spectra when the quality of the poor solvent is changed in good solvent (chloroform) / poor solvent (methanol) mixtures. With increasing volume fraction of methanol in mixtures, the absorption spectra of P3HT and P3DT red-shift, peaking at maximum wavelength of 495nm (P3HT) and 510nm(P3DT). Furthermore, the absorption spectra of the two polymers in chloroform blue-shift as the temperature rises. P3HT shows 4.73nm blue-shifts at 50℃ in contrast to the case at 20℃, while P3DT blue-shifts about 5.04nm. The photoluminescence spectra of the two polymers in mixed solution are also investigated, which show that the luminescence spectra shift to longer wavelength with an accompanying drop in the PL intensity as methanol is increased. The absorption and emission spectra of the two polymers in a poor solvent and a thin film are similar, which indicate that a similar longer conjugation length in the two cases. It could conclude that the polymers exist almost the same conformations and aggregations in both a poor solvent and a thin film. P3DT exhibits more sensitive spectra properties (big red-shifts in both absorption and luminescence spectra in poor solvents and large blue-shifts at high temperature) with contrast to P3HT, which imply that long side alkyl may improve the chromic properties of the polymer. 展开更多
关键词 SOLVATOCHROMISM THERMOCHROMISM Poly(3-alkyl)thiophenes Photoluminescence spectra
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