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采用甲醇钠/甲醇酯转化-苯基硼酸( PBA )衍生化-气相色谱质谱( GC-MS )联用技术方法,测定食用植物油中脂肪酸3-氯-1,2-丙二醇酯(简称3-MCPD酯)。结果表明,食用植物油棕榈酸油、芝麻油和菜籽油脂3-MCPD酯含量比较高,其含量由高到低分别为51250μg/kg ,10400μg/kg和9990μg/kg。食用菜籽油在保持温度220℃、常压条件不变的情况下,经其他不同脱除工艺处理30 min,油脂中所含的3-MCPD酯无明显变化,这表明油脂的精炼脱臭工序中脱臭温度可能是产生3-MCPD酯的主要原因。 相似文献
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Sliding friction and wear experiments using Cu-La2O3-graphite composites against Cu-5 wt.%Ag alloy ring were conducted at a constant sliding speed of 10 m/s, a current density of 10 A/cm2 and a load of 2.5 N/cm2. These composites with different La2O3 and graphite contents were fabricated by hot-pressing. Physical and mechanical properties of the composites were examined. Morphologies of the worn surface of composites were observed using optical microscopy. X-ray photoelectron spectroscopy spectra were used to study compositions of the lubricating film. The results showed that with the increasing addition of La2O3, hardness, flexural strength and electrical resistivity increased, but the relative density dropped. The friction coefficient increased with the increasing addition of La2O3. Composite containing 3 vol.% of La2O3 and 37 vol.% of graphite showed the best wear resistance. The main wear mechanisms of composites were abrasive wear, oxidative wear and adhesive wear. 相似文献
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针对切削颤振降低恒功率约束自适应加工过程效率的问题,研究了融合颤振控制的恒功率约束自适应加工方法。通过切削试验分析了颤振对机床主轴功率的影响,给出了控制恒功率约束自适应加工过程中颤振的必要性。基于模糊理论开发了模糊控制器,通过调整主轴进给实现了切削过程的恒功率约束。基于变转速抑制切削颤振理论调整机床主轴转速,实现了颤振抑制。以加工效率为目标制定了机床主轴进给和转速的调整原则,实现了融合颤振控制的恒功率约束自适应加工。通过切削实验验证了研究结果的有效性。 相似文献
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采用甲醇钠/甲醇酯转化—苯基硼酸(PBA)衍生化—气相色谱质谱(GC—MS)联用技术方法,测定食用植物油中脂肪酸3-氯-1,2-丙二醇酯(简称3-MCPD酯)。结果表明,食用植物油棕榈酸油、芝麻油和菜籽油脂3-MCPD酯含量比较高,其含量由高到低分别为51 250μg/kg,10 400μg/kg和9 990μg/kg。食用菜籽油在保持温度220℃、常压条件不变的情况下,经其他不同脱除工艺处理30 min,油脂中所含的3-MCPD酯无明显变化,这表明油脂的精炼脱臭工序中脱臭温度可能是产生3-MCPD酯的主要原因。 相似文献
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