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A novel complex Pd(C4H2O4)(C4H8N2)0.5 has been synthesized by solvent thermal synthesis and used as a heterogeneous catalyst for direct synthesis of diphenyl carbonate (DPC) by oxidative carbonylation of phenol. In the reaction system of Pd(C4H2O4)(C4H8N2)0.5/Cu(OAc)2/ tetrabutylammonium bromide/ hydroquinone/ 4A molecular sieves, the effect of reaction temperature, time and CO pressure on catalytic activity were investigated, and the results revealed that the catalyst could catalyze oxidative carbonylation of phenol effectively. Under suitable reaction conditions of T=90℃, t=4 h, p(O2)=0.3 MPa, p(CO)=3.9 MPa and CH2Cl2 as solvent, the turnover number (TON) of diphenyl carbonate can reach about 13.50 (mol-DPC/mol-Pd), which is higher than the TON for oure PdCl2 under the same reaction conditions. 相似文献
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为研究穿越溶洞不良地质因素的高速公路隧道衬砌结构应力稳定性,利用Abaqus数值平台开展了溶洞分布方位、溶洞净距因素的影响下衬砌结构断面上大、小主应力变化的分析。衬砌断面上大、小主应力均呈“双U”形特征,而溶洞方位角90°、270°下衬砌断面大主应力水平最高,而小主应力以此两方案下最低;溶洞分布在此两方位上,对隧道衬砌结构应力稳定性影响最大。溶洞净距每增大3 m,衬砌断面上平均大、小主应力分别可减小27.9%及增大45.8%;净距愈小,谷值大、小主应力段持续面分别为更小与更大趋势;净距参数对衬砌结构影响集中在量值水平与谷值分布。隧道穿越的溶洞净距过小,应考虑技术处理降低其敏感影响。总结的经验可为桥隧工程中研究溶洞等不良地质特征影响提供参考。 相似文献
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苹果汁褐变控制技术研究进展 总被引:5,自引:1,他引:4
苹果加工是全球水果加工业的重点,其中苹果汁是苹果加工业最重要、产量最大的产品。苹果汁的色泽是其重要的质量指标,是消费者判断其质量的重要依据。苹果汁的颜色质量主要决定于其在生产过程中的褐变情况。根据其褐变机理,苹果汁的褐变主要包括酶促褐变与非酶褐变。由于苹果原料富含酚类化合物和活性较高的多酚氧化酶,酶促褐变是其主要的褐变方式。因此,控制苹果汁的褐变,尤其是酶促褐变,对保障其质量和消费者接受性具有重要意义。该文在查阅大量文献的基础上,对苹果汁褐变机理(酶促褐变与非酶褐变)、褐变控制技术(物理控制技术、褐变抑制剂的添加及其他控制技术)进行了全面综述。同时对该领域存在的问题及今后的发展方向进行了阐述。 相似文献
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A novel complex Pd(C4H2O4)(C4H8N2)0.5 has been synthesized by solvent thermal synthesis and used as a heterogeneous catalyst for direct synthesis of diphenyl carbonate (DPC) by oxidative carbonylation of phenol. In the reaction system of Pd(C4H2O4)(C4H8N2)0.5/Cu(OAc)2/ tetrabutylammonium bromide/ hydroquinone/ 4A molecular sieves, the effect of reaction temperature, time and CO pressure on catalytic activity were investigated, and the results revealed that the catalyst could catalyze oxidative carbonylation of phenol effectively. Under suitable reaction conditions of T=90℃, t=4h, p(O2)=0.3 MPa, p(CO)=3.9 MPa and CH2Cl2 as solvent, the turnover number (TON) of diphenyl carbonate can reach about 13.50 (mol-DPC/mol-Pd), which is higher than the TON for pure PdCl2 under the same reaction conditions. 相似文献
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黄豆营养丰富,黄豆酱味道丰富、鲜美,为了迎合大众对减盐健康食品的需求,使用黄豆进行制曲、发酵得到减盐黄豆酱,并监测发酵过程中理化指标的变化规律。通过相关性分析,感官评分与氨基酸态氮含量呈现显著正相关(P<0.05),说明氨基酸态氮含量可作为判断发酵终点的指标,通过感官评分与氨基酸态氮含量的判定, 45 d达到发酵终点,发酵成熟的黄豆酱水分含量为56.3%,盐分含量为5.2%,总酸含量为1.28%,氨基酸态氮含量为0.62%,感官评分为28分(满分30分)。以减盐黄豆酱为基底,与减盐发酵辣椒酱混合后发酵可得到减盐黄豆瓣酱,可在一定程度上拓宽麻辣调味品开发与加工过程的原料丰富程度。 相似文献
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