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《Food research international (Ottawa, Ont.)》2002,35(7):627-633
A simple, rapid and accurate analytical method for direct quantification of phenolic antioxidants BHA, BHT and TBHQ in lipid-containing foods was established by GC-FID with a fused silica capillary column. With the present method, as little as 30–60 mg of the commercial samples including cooking oil, fish oil, butter, margarine, cheese, mayonnaise and salad dressing was required to be dissolved in 1 ml diethyl ether. After the addition of 8-quinolinol as an internal standard, 0.1 μl of the mixture was directly injected into the gas chromatograph with glass wool inserted in the glass liner of the injector port. Analysis of each sample required only 18 min. The recoveries of antioxidants from cooking oil were 92.5–108.4% with coefficients of variation below 7.4%. Among 27 samples, three cooking oil, two fish oil, one butter and one margarine samples were found to contain more than 200 ppm total antioxidants. 相似文献
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截割头是掘进机直接实现截割功能的关键部件,其设计在一定程度上直接决定了整机的性能。采用混凝土制作煤岩,对自制煤岩进行单轴压缩试验,确定其抗压强度和弹性模量。针对掘进机截割煤岩过程的复杂性,以部分断面掘进机截割头为研究对象,基于单轴压缩试验所确定的物理参数,利用动力学有限元软件LS-DYNA建立截割头截割煤岩过程仿真模型,探讨了截齿切削角和旋转角对截割载荷、载荷波动和截割比能耗的影响规律。由仿真结果可知,当截齿的切削角在48°~50°范围,旋转角在12°~16°范围时,截割头的截割能力较佳;将由试验确定的自制煤岩截割力矩时域曲线与仿真结果进行对比,验证了所建立的仿真模型的正确性。上述研究为部分断面掘进机截割头截割性能的改善提供了理论基础,同时为其他类型截割或切削问题的研究提供了理论借鉴。 相似文献
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对传统等通道转角挤压工艺(equal channel angular extrusion,ECAE)进行改进,提出一种新型剧烈塑性变形法(severe plastic deformation,SPD)——等通道球形转角膨胀挤压(equal channel angular expansion extrusion with... 相似文献