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合成了三类稀土硼氢化合物Ln(BH4)3(THF)3[Ln=Er(1),Yb(2)]、[(Me3Si)2NC(NCy)2]Ln(BH4)2(THF)2[Cy=C6H11,Ln=Er(3),Yb(4)]和(ArO)Ln(BH4)2(THF)2[Ar=C6H2-2,4,6-t-Bu3,Ln=Er(5),Yb(6)],首次研究了它们催化环氧环己烷(CHO)开环聚合的性能.其活性顺序为5~6>1~3>2>4,说明吸电性配体以及Lewis酸性较大的稀土元素对金属硼氢化物催化聚合活性是有利的.温度越高,催化剂催化活性越好.聚合物分子量在1万左右,分子量分布在2.2左右. 相似文献
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气升式外循环淤浆反应器的气含率和传质的研究 总被引:4,自引:1,他引:4
在气升式外循环环流反应器中,对空气-水两相系统的气含率■_(go)和气-液氧体积传质系数进行了研究,获得关联式:■_(go)=1.384(u_G/(u_G+u'_L)~(0.34)u_G~(0.71)k_Lα=0.0463(u_G/(u_G+u'_L)~(0.24)u_G~(0.52)对空气-水-α-氧化铝三相淤浆系统,采用丝网过滤将催化剂留于反应器上升管中。此时,上升管中气含率■_(go)和传质系 k_La可用下面公式来计算:■=1.384/(1+0.504■_s~(0.13))(u_G/(u_G+u'_L))~(0.34)u_G~(0.71) (■_s=0.001~0.05)■ 相似文献
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概述了甲阶酚醛树脂的合成方法,并提出了以绝热温升和温升时间来考评可发性酚醛树脂化学反应特性的观点。与传统热反应考评参数相比较,结果认为化学反应参数和热反应参数不可相互替代,两者结合能较全面反映可发性酚醛树脂的性能。 相似文献
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宝钢分公司厚板厂5m轧机是国内第一条特宽幅厚板生产线,油膜轴承是厚板轧机的主要设备之一,正确认识和掌握其特点是提高厚板生产的关键环节.分析了5m轧机油膜轴承的结构特点,简述了厚板轧机油膜轴承的润滑系统及油膜轴承的自位机构,并结合轧机调试时出现的问题对自位机构进行分析和改进.同时结合现场工作经验对开工初期支承辊辊颈和油膜轴承锥套接触部分出现大量斑点的现象进行了分析,并改进装配工艺,最后消除了斑点的产生. 相似文献
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Complexes of lanthanide trisborohydrides, formally Ln(BH4)3(THF)n (Ln=La, Ce, Sm, Yb), were synthesized and their catalytic activity for polymerization of ε-caprolactone was studied. All the complexes can catalyze this polymerization. It was found that the catalytic activities decreased in the order of La>Ce>Sm>Yb. The crystal structure of cerium trisborohydride was determined for the first time by single crystal X-ray diffraction analysis. It is an ionic pair complex of [Ce(BH4)2(THF)5][Ce(BH4)4(THF)2]. The cationic part involves two η3-BH4 ligands, while the anionic part involves two η3-BH4 groups and two η2-BH4 groups. 相似文献
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Rareearthshavebeenextensivelyusedinindus try ,agricultureandmodernbiologicalmedicine ,andmoreandmoreREelementsareenteringintothebio logicalcircle .Manystudieshaveindicatedthattheyhavesignificanteffectsonallsystemsofhumanandanimalorganisms[1~5] .Previousarticlesreportedthatrareearthsmayaffectthedigestivefunctionandmaypromotedevelopmentofanimals .Thegastricacidandpepsinsecretionsareelevatedatadministrationoflow erdosesofrareearth ,whereasmarkedlydecreasesatadministrationofhigherdosesinratsandr… 相似文献