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241.
建立了高效液相色谱-串联质谱同时定量和确证猪肉中3-甲基喹喔啉-2-羧酸(MQCA)残留量的检测方法。试样用0.3 mol/L盐酸溶液水解提取,加入乙腈和乙酸乙酯萃取,再用0.1 mol/L氢氧化钠溶液反萃取,阴离子交换固相萃取柱净化,经Agilent Eclipse Plus C18柱(50 mm×3.0 mm,1.8 μm)分离,采用液相色谱-串联质谱仪检测,基质匹配添加标准曲线定量。MQCA在1.0~50 μg/L范围内线性相关系数大于0.99,在0.5、1.0、5.0 μg/kg加标水平下其回收率为90.5%~119.6%,相对标准偏差为3.14%~4.22%。方法可用于猪肉中MQCA残留量的快速定量和确证检测。 相似文献
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含受电子生色基团烯类单体 对乙烯氧基甲基苯甲腈的合成及其荧光“结构自猝灭”效应杜福胜李福绵(北京大学化学学院北京100871)关键词对乙烯氧基甲基苯甲腈,吸收光谱,荧光光谱,“结构自猝灭”效应我们曾经报道过一系列含有给电子荧光生色基团的丙烯酰类及马... 相似文献
243.
多环芳烃暴露的生物标志物——尿中羟基多环芳烃 总被引:9,自引:0,他引:9
多环芳烃(PAHs) 是典型的持久性有机污染物,在职业高PAHs 暴露环境下,容易诱发肺癌、皮肤癌等癌症。对PAHs 的暴露评价可为流行病学研究和污染物风险评价等提供有效的数据。由于暴露途径的复杂化,采用尿样中PAHs 的代谢产物———羟基多环芳烃作为标志物来综合评价人体对PAHs 的内暴露情况已经成为研究的热点。本文系统介绍了多环芳烃的吸收、代谢、尿中PAHs 代谢产物的主要存在形式、主要的生物标志物以及它们的主要影响因素。 相似文献
244.
Proton-decoupled, ~(13)C FT-NMR (operating at 50.3 MHz) is used to determine spin-latticerelaxation time (T_1), nuclear Overhauser enhancement (NOE), linewidth and chemical shift of 1,2-polybutadiene as a function of temperature in CDCl_3 solution and the temperature dependence ofmolecular motion of 1,2-polybutadiene has been investigated with these NMR relaxation parameters.It is found that jumps of NOE and linewidth vs. temperature appear between-1℃and -30℃. Theminimum of nT_1 vs. temperature for all carbons occur at about -45℃. 相似文献
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Magnetite (Fe3O4) nanoparticles were synthesized by chemical precipitation. To reduce the aggregation of Fe3O4 nanoparticles, an effective surface modification method was proposed by grafting polystyrene onto the Fe3O4 particles. The results of Fourier transform infrared spectra and elemental analysis showed that the polymer chains have been successfully grafted from the surface of the Fe3O4 nanoparticles and that the percentage of grafting can reach 73%. Transmission electron microscope showed that grafted polymer chains on nanoparticles could prevent the aggregation of Fe3O4 nanoparticles markedly in toluene and improve their compatibility with organic phase. Another finding was the grafting reaction did not alter the crystalline structure of the Fe3O4 nanoparticles according to the X-ray diffraction patterns, and the saturation magnetization of PS-Fe3O4 nanoparticles was found to be lower than bulk magnetite. 相似文献
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Yanxia Li Yuming Yang Fusheng Yu Lisong Dong 《Journal of Polymer Science.Polymer Physics》2006,44(1):9-21
The surface and interface morphologies of polystyrene (PS)/poly(methyl methacrylate) (PMMA) thin‐film blends and bilayers were investigated by means of atomic force microscopy (AFM) and X‐ray photoelectron spectroscopy. Spin‐coating a drop of a PS solution directly onto a PMMA bottom layer from a common solvent for both polymers yielded lateral domains that exhibited a well‐defined topographical structure. Two common solvents were used in this study. The structure of the films changed progressively as the concentration of the PS solution was varied. The formation of the blend morphology could be explained by the difference in the solubility of the two polymers in the solvent and the dewetting of PS‐rich domains from the PMMA‐rich phase. Films of the PS/PMMA blend and bilayer were annealed at temperatures above their glass‐transition temperatures for up to 70 h. All samples investigated with AFM were covered with PS droplets of various size distributions. Moreover, we investigated the evolution of the annealed PS/PMMA thin‐film blend and bilayer and gave a proper explanation for the formation of a relatively complicated interface inside a larger PS droplet. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 9–21, 2006 相似文献
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Shao Huijuan Wei Yongfen Li Fusheng 《Journal of Radioanalytical and Nuclear Chemistry》2019,319(1):315-326
The fixation capability of cesium on five recycling materials was compared through two sets of sorption experiments using the materials mixed with and without soil. The estimated Freundlich constant K and the distribution of sorbed cesium on the materials revealed a general order of the fixation capability as carbonized sludge > coconut shell biochar > incinerated sewage sludge ash > rice husk biochar > slag. Parametric strong positive correlations were found existent between the fixation capability of cesium and the property-related indexes of the materials such as cation exchange capacity, organic matter content and the potassium concentration.
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