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621.
Co-Pd bimetallic catalysts immobilized with four kinds of resins with different specific areas were prepared by means of the solvated metal atom impregnation (SMAI) method. The results of the XRD and the magnetic measurement showed that as the specific area of the resin increased, the particle sizes of Co and Pd on the catalysts with the same metal content decreased, so the catalytic activity of the catalysts for the hydrogenation of diacetone alcohol as well as the reduction of oxygen on the fuel cell electrode increased. Below 140 , the conversion of diacetone alcohol increased as the reaction temperature increased, and above 140 , the conversion decreased because of the rupture of the resin.  相似文献   
622.
IntroductionInclusioncompoundshavebeennotedinrecentyearsandresorcinol typecalix [4 ]arenehasbeenstudiedfortheirinclusionabilitiesbyScheiderandBugleretal[1— 3] .Thepolyolmoietiesincalix[4 ]re sorcinareneformrigidhydrogen bondingnetworks[4 ] ,andcalix [4 ]resorcinare…  相似文献   
623.
IntroductionSince Wilson and co- workers successfullysynthesized three- dimensional microporousaluminophosphates (Al PO4 - n ) [1] in the 1 980 s,much attention has been focused on the explorationof1 - D chain,2 - D layer and3 - D open- frameworkmetal phosphates from aqueous or non- aqueoussystems.The number of metals incorporated intothe frameworks of these materials is continuouslyincreasing and the metals include Be[2 ] ,Ga[3] ,In[4 ] ,Sn[5] ,Sb[6 ] ,and the transition metals Zn[7] ,Ni…  相似文献   
624.
IntroductionThe recent development of free radical biologyand medicine has provided a great deal of clinicaland experimental evidence indicating that the freeradical induced peroxidation of membrane lipids isassociated with a variety of chronic healthproblems,such as cancer,atherosclerosis andageing[1,2 ] . Both natural and synthetic antioxidantshave been used to trap peroxyl radicals and/orinitiating radicals to protect the membrane lipidsagainst free radical chain reactions,and hence mayhave…  相似文献   
625.
IntroductionBioinformatics is coming with Human GenomeProject(HGP) . With the explosions of sequence,structural and other information available ,bioinformatics is playing an increasingly large rolein the study of fundamental biomedical problems.At present and in the near future,it is the mainchallenge for bioinformatists to make gene dicoveryand annotation of human genome sequences whenthe vast amount of data is produced by the highthroughput genome sequencing in a large scale andautomated m…  相似文献   
626.
IntroductionAmrinon,asyntheticbipyridinederivative,nonglycosideandnoncatecholaminecar-diotonicstimulant,iscurrentlyusedinthetreatmentoftheheartfailureandforcardiovascu-larsupportinpediatricpatients.Itpossessespotentcardiacandbloodvesselspreadingef-fe…  相似文献   
627.
吴德印  任译  刘玉明  田安民  H.SUN 《化学学报》1998,56(10):948-955
用从头算和密度泛函数理论研究了1,3-二氟丙烷的构象和电子结构。在计算的各种理论水平下,GG构象是最稳定构象,AG构象次之。利用分子力场的非键作用定量化旁式效应,由MM2力场的非键参数计算的结果较为合理。对于GG和AG构象,在HF/6-31G^*和HF/6-31+G^*^*水平预测的构象分布与实验值接近。  相似文献   
628.
梁国明  任译 《化学学报》2005,63(23):2163-2168
采用超分子-连续介质(PCM)模型,在密度泛函B3LYP/6-311++G**水平上对水溶液中亚硝基甲烷异构化反应的机理进行了理论研究.结果表明,在水溶液中亚硝基甲烷可以通过两条反应途径(Ⅰ和Ⅱ)经质子迁移得到更稳定的重排产物--反式甲醛肟,但优势反应途径与在气相反应不同.在水溶液中亚硝基甲烷异构化反应最有可能的途径Ⅰ是通过氢迁移先生成顺式甲醛肟,然后绕N-O键旋转生成更稳定的反式甲醛肟.并且由于水分子的催化作用使得反应活化能从气相中240.6和196.2 kJ/mol分别降低至水溶液中的61.7和92.1 kJ/mol.  相似文献   
629.
The authors consider the simplest quantum mechanics model of solids,the tight binding model,and prove that in the continuum limit,the energy of tight binding model converges to that of the continuum elasticity model obtained using Cauchy-Born rule.The technique in this paper is based mainly on spectral perturbation theory for large matrices.  相似文献   
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