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建立了调味制品(调味料、番茄酱、酱油、花椒)、饮料(碳酸饮料、乳饮料、果汁)、肉制品(香肠、肉罐头、肉汤)、水果制品(果冻、果酱)、水产品(干鱼肉、鱼罐头、鱼肉泥)、小吃类(油炸薯片、糖果、巧克力)等18种食品中黄樟素、异黄樟素、二氢黄樟素含量的分析方法。样品在氯化钠盐析作用下,经二氯甲烷-乙腈提取,无水硫酸钠-氟罗里硅土柱吸附极性物质和水分。复杂样品需再经PRi ME HLB固相萃取柱(SPE)净化,5%苯基-95%甲基聚硅氧烷毛细管气相色谱柱分离,选择离子质谱技术监测,内标法定量。在最佳实验条件下,3种黄樟素在25~5 000μg/kg范围内呈良好的线性关系,相关系数(r2)≥0.9981,方法检出限(LOD)和定量下限(LOQ)分别为20μg/kg和50μg/kg,3个加标水平的回收率为77.6%~100.9%,相对标准偏差(RSD)为3.7%~13.6%。多种实际样品的测定结果表明,该方法准确可靠,适用于食品中3种黄樟素及其衍生物的定量和定性分析。 相似文献
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Starting from the notion of thickness of Parks we define a notion of robustness for arbitrary subsets of Rk and we investigate its relationship with the notion of positive reach of Federer. We prove that if a set M is robust, then its boundary ∂M is of positive reach and conversely (under very mild restrictions) if ∂M is of positive reach, then M is robust. We then prove that a closed non-empty robust set in Rk (different from Rk) is a codimension zero submanifold of class C1 with boundary. As a partial converse we show that any compact codimension zero submanifold with boundary of class C2 is robust. Using the notion of robustness we prove a kind of stability theorem for codimension zero compact submanifolds with boundary: two such submanifolds, whose boundaries are close enough (in the sense of Hausdorff distance), are diffeomorphic. 相似文献
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本文采用XRF分析技术,用C语言设计运算软件,快速和精确地同时检测合金薄膜材料的质量厚度及组成含量,并呆计算合金膜的体积密度和线性厚度,检测结果的相对误差在3%左右。 相似文献
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We show that X-ray scattering techniques can be used for the assessment of individual layer thicknesses inside complicated semi-conductor heterostructures dedicated to the opto-electronic domain. To this end, we propose methods to overcome two main drawbacks coming from: (1) the complexity of the X-ray profiles and, hence the difficulty to use model-dependent tools such as fitting procedures and (2) large dynamics in intensity due to numerous high diffraction superlattice peaks from superlattices which limit the use of the model-independent Fourier-inversion method.We demonstrate first the reliability of the Fourier-inversion method applied to high-resolution X-ray diffraction profiles curve from quantum well infrared photodetectors heterostructures, complementary to the model-dependent fitting tools. Then, a wavelet-transform-based procedure has been successfully used on X-ray reflectometry profiles containing intense SL Bragg peaks. 相似文献
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Mehmet Çopuroğlu Shane O’Brien Gabriel M. Crean 《Journal of Sol-Gel Science and Technology》2006,40(1):75-82
A hybrid material system consisting of (3-glycidyloxypropyl)trimethoxysilane, dimethyldimethoxysilane and zirconium(IV) n-propoxide was prepared. The influence of processing parameters including Zr content, UV irradiation and sol ageing on the
properties of the resultant thin films was discussed. Refractive index, at 633 nm, and reflectance measurements were performed
and near-field waveguide images of the samples were taken. Optical propagation loss measurements, at 633 nm, were studied.
Film thickness and cross-sectional scanning electron microscopy images were obtained as a function of process conditions.
FT-IR spectroscopy was used to monitor chemical reaction pathways in the system during processing. It was demonstrated that
the crosslinking of epoxy groups in the structure, along with inorganic network formation as a result of sol-gel reactions,
was the primary reason for the changes in the optical and physical properties of the system. As Zr containing species and/or
UV irradiation may be employed to crosslink the epoxy groups in the structure, the optical and physical properties of the
system can be tuned by optimal combination of these two crosslinking methods, as well as sol ageing process. 相似文献