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Apatite-type lanthanum silicate with special conduction mechanism via interstitial oxygen has attracted considerable interest in recent years. In this work, pure powder of La9.33-2x/3MxSi6O26 (M=Mg, Ca, Sr) is prepared by the sol-gel method with sintering at 1000°C. The powder is characterized by X-ray diffraction (XRD) and scan-ning electron micrograph (SEM). The apatite can be obtained at relatively low temperature as compared to the con-ventional solid-state reaction method. The measurements of conductivity of a series of doped samples La9.33-2x/3MxSi6O26 (M=Ca, Mg, Sr) indicate that the type of dopant and the amount have a significant effect on the conductivity. The greatest decrease in conductivity is observed for Mg doping, following the Ca and the Sr doped apatites. The effect is ultimately attributed to the amount of oxygen interstitials, which is affected by the crystal lat-tice distortion arising from cation vacancies. 相似文献
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茶树花香气成分研究及其香精的制备 总被引:1,自引:0,他引:1
用石油醚浸提获得茶树花精油,利用气质分析测定了其香气成分,用β-环糊精将茶树花精油制成茶树花香精,并对茶树花浸膏、精油和香精进行了感官评价.研究结果表明:浸膏和精油得率分别是1.66%和10.4%,精油中的香气成分包括棕榈酸、丁二酸、咖啡因、邻苯二甲酸二异丁酯等25种成分,β-环糊精包埋获得的茶树花香精更易于接受,且可以达到缓释和保护作用. 相似文献
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高效液相色谱串联四极杆质谱法同时测定豆芽中7 种药物残留 总被引:4,自引:0,他引:4
为加强对豆芽类产品的监管,研究豆芽中7 种药物(6-苄基腺嘌呤、4-氯苯氧乙酸、2,4-D、赤霉素、多菌灵、腐霉利和恩诺沙星)同时检测的方法。该方法使用乙腈对豆芽中7 种药物进行同时提取,使用高效液相串联四极杆质谱仪对上述7 种药物进行检测。7 种药物在0.01~10 μg/mL(多菌灵和恩诺沙星在0.01~1 μg/mL)内线性良好(R2≥0.987)。两种豆芽中7 种药物的3 个添加量(分别为0.002、0.2、0.5 mg/kg)回收实验结果表明:7 种药物的回收率为60.31%~108.51%,相对标准偏差为1.03%~13.10%,方法检出限为0.010 5~0.125 μg/kg。 相似文献
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X光能谱仪在低束流条件下能对Z≥11的所有元素作快速无标样微区定量分析,而且适合于比较粗糙的表面分析,故其应用日益扩大。但能谱分析的准确度较波谱低,故能谱工作者应掌握日常所操作仪器其分析误差最小的测试条件,从而提高分析结果的准确性。本方法是在EXAC—2000/DX系统上试验的,原则上可在各类能谱仪上应用。按本方法所定出的测试条件对一般样品作无标样定量分析,其相对误差通常可在70%以下。 相似文献
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