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采用大位阻的有机锂试剂或格氏试剂与卤代烯烃偶联合成了7种大位阻取代烯烃. 以Oxone(KHSO5)作为氧化剂, 分别在D-果糖衍生酮和(2S,5R)-2-异丙基-5-甲基环己酮为催化剂的催化下, 将合成的7种大位阻取代烯烃转变成了7个大位阻的手性环氧化合物. 其中以D-果糖衍生酮的对映选择性最好, 当双键碳上含有3个取代基时, 对映选择性最高, e.e.值为96.8%~99.5%. (2S, 5R)-2-异丙基-5-甲基环己酮的对映选择性较差, 无论是一取代的烯烃还是三取代的烯烃, 其e.e.值均介于25.6%~34.1%之间. 相似文献
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IntroductionTheresistivityρ(T)ofsuperconductorsisdescribedasfollows[1]:κ(T<Tc)ρ(T)=ρ∥=AT(T>Tc,(abplane)ρ⊥=BT(T>Tc,(caxis)(1)HereA<B.Expression(1)accuratelysummariesuptheresistivitythroughmeasuringtheanisotropyconductivityofasinglecrystalofYBa2Cu3O(7-… 相似文献
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IntroductionHighspinmoleculeshaveattractedmuchinterest,becausetheycanbeservedasthebuildingblockformagneticmaterials[1-2].ItissuggestedbyFukutome[3]andDoughertyetal.[4]thatthehighspinmoleculescanbedividedintotwocomponents:thespin-containing(SC)fragmen… 相似文献
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Novel conjugated polymers with aza-15-crown-5 as pendant groups, P1 were synthesized by the Sonogashira coupling reaction. The polymer P1 was found to show fluorescence en-hancement response towards Ba2+. The gradual recovery and turning-point of emission intensity of polymers appeared in the addition of Ba2+, which provided good evidence for the fluorescence amplification mechanism of conjugated polymers. 相似文献
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本文依据实验结果拟定了轴对称杯杆型复合挤压出现杆部表面裂纹时的金属流动速度场,以此为基础,并藉助于上限原理和最小能量原理,获得了此类复合挤压时杆部表面裂纹形成的必要条件。同时,研究了此类复合挤压杆部变形开裂区与正挤,反挤部分变形程度(εf,εb)组合、坯料相对余厚(T/R_0)、摩擦因数m值以及模具工作带相对长度(l_f/R_0,l_b/R_0)的关系.从而可以估测低塑性材料在进行此类复合挤压时杆部是否形成表面裂纹.LY12和LC4材料的试验结果与本文的分析结果具有很好的一致性. 相似文献
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SU Zhong min ** CHEN Li hua WU Li xin XU Hong bin ZHU Dong xia WANG Rong shun . The Chemistry Department Functional Material Institute Northeast Normal University Changchun P. R. China . Institute of T 《高等学校化学研究》2002,18(3)
IntroductionSince C. W. Tang firstly reported theelectroluminescence of 8- hydroxyquinolinealuminium[1] ,much attention has been paid to themetal complexes as electro- luminescent materials.Based on a series of experimental data,it has beenknown that the electroluminescence of metalcomplexes with heterocyclic ligands containing Nand O elements mainly results from the tripletstatetransition.For some transitional metal complexes,there exist the transitions from metal to ligand( MLCT) at thei… 相似文献