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用经验赝势方法计算了体ZnSe以及ZnSe/GaAs单异质结系统中ZnSe外延层г、X、L等特殊对称点导带底能量随压力的变化。结果表明,同Si、Ge、GaAs等半导体材料不同,ZnSe的X点导带底具有正的压力系数,但比г点的压力系数小,这是ZnSe材料以及ZnSe基异质结构材料发生直接禁带向间接禁带的转变时所需转变压力较大的根本原因。研究了ZnSe/GaAs异质结构中晶格失配造成的应变对外延层г、X、L对称点压力系数的影响,表明这种晶格失配造成的应变可以极大地减小ZnSe外延层材料由直接禁带向间接禁带的转变压力。 相似文献
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SynthesisandMagnetismof2┐Hydroxy┐1,3┐propylene┐bis(oxamato)┐bridgedCoⅡCuⅡCoⅡComplexesMIAOMing-ming,CHENGPeng,LIAODai-zhengJIA... 相似文献
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Shi‐jia Liu Ling Zhou Jun Zhang Chang‐yin Li Zi‐xiu Liu Wen‐zheng Ju 《Biomedical chromatography : BMC》2013,27(4):515-519
A highly sensitive liquid chromatography–tandem mass spectrometry method was developed and validated for the determination of limonin in beagle dog plasma using nimodipine as internal standard. The analyte and internal standard (IS) were extracted with ether followed by a rapid isocratic elution with 10 mm ammonium acetate buffer–methanol (26:74, v/v) on a C18 column (150 × 2.1 mm i.d.) and subsequent analysis by mass spectrometry in the multiple reaction monitoring mode. The precursor to product ion transitions of m/z 469.4 → 229.3 and m/z 417.2 → 122.0 were used to measure the analyte and the IS. The assay was linear over the concentration range of 0.625–100 ng/mL for limonin in dog plasma. The lower limit of quantification was 0.312 ng/mL and the extraction recovery was >90.4% for limonin. The inter‐ and intra‐day precision of the method at three concentrations was less than 9.9%. The method was successfully applied to pharmacokinetic study of limonin in dogs. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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银环蛇蛇蜕的化学成分研究Ⅱ . 脂肪酸和氨基酸组分 总被引:1,自引:0,他引:1
用色谱-质谱(GC-MS)联用技术分析了银环蛇蛇蜕的脂肪酸成分,鉴定出36种脂肪酸(饱和酸28种不饱和酸8种),在蛇蜕中发现16种饱和二元酸,并发现了自然界中少见的奇数碳脂肪酸14种及支链酸2种,用氨基酸自动分析仪测定了蛇蜕水提取液中的13种游离氨基酸,酸性水解液中17种氨基酸,在蛇蜕中发现存在牛 磺酸。 相似文献
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反应烧结碳化硅复合材料的磨损机理研究 总被引:1,自引:3,他引:1
采用销-盘摩擦磨损试验机考察了反应烧结碳化硅及含Ni碳化硅复合材料在不同温度下的干摩擦磨损性能。结果表明,Ni有利于改善反应烧结碳化硅复合材料的摩擦磨损性能。SEM磨损表面和亚表面分析表明,复合材料在常温下的磨损机理为削和犁沟;600℃下反应烧结碳化硅的磨损机理为表面裂纹形成及断裂;而含Ni碳化硅复合材料的磨损机理为亚表面裂纹扩展导致表面局部剥落。 相似文献