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81.
Polymer-supported reagents for organic synthesis are enjoying a renewed popularity with the emergence of combinatorial chemistry in recent years1. 4-(Arylseleno)morpholines formed in situ are useful -seleno-introducing reagents for saturated aldehydes2. -Sele- noaldehydes, as a frequently used intermediates, can be converted into -haloaldehydes by halogenating reaction3. However, organic selenium reagents always have a foul smell and are quite toxic, which is often problematic in organic sy…  相似文献   
82.
新型双核配合物的形成、与DNA的作用机制及荧光性质研究   总被引:5,自引:0,他引:5  
利用紫外、荧光和粘度等方法研究了含不同配体的钌(II)配合物[Ru(phen)2CImP]2+(CImP=3,4-二羟基-咪唑并[4,5-i][1,10]邻菲咯啉)和[Ru(phen)2TPPZ]2+(TPPZ=四吡啶[3,2-a:2',3'-c:3',2'-h:2'',3''-j]吩嗪)与DNA的作用机制, 并研究了配合物与Zn2+配合后荧光性质变化. 结果表明[Ru(phen)2TPPZ]2+与DNA以插入模式作用, 而[Ru(phen)2CImP]2+与DNA则以沟面结合模式作用. 向配合物溶液中滴加Zn2+后, 配合物[Ru(phen)2TPPZ]2+和[Ru(phen)2CImP]2+均可以与Zn2+形成双核配合物[Ru(phen)2(TPPZ)Zn]4+和[Ru(phen)2(CImP)Zn]4+, 配合物的荧光减弱. 与DNA作用后, 配合物仍可以与Zn2+配位形成双核配合物, 但[Ru(phen)2(TPPZ)Zn]4+保持插入模式与DNA作用, 配合物的荧光减弱. 而[Ru(phen)2(CImP)Zn]4+与DNA则由沟面结合改为插入结合, 配合物的荧光增强.  相似文献   
83.
The photochemistry of the vitamin D family and their precursors has been the subject of extensive studies for many years1-4. Most of the studies focus on the photoisomer- ization of 7-dehydrocholesterol and that of tachysterol to previtamin D3, which is of commercial importance in the synthesis of vitamin D34, 5. Recently the cis/trans isomerization of vitamin D analogs (Scheme 1) draws attention because of its importance in the synthesis of hydroxylated vitamin D metabolites6. However, o…  相似文献   
84.
The similar electrochemical oxidation behaviors of hydroxypivalaldehyde in ionic liquids (ILs) medium, C4MIMPF6, C4MIMBF4 and CsMIMPF6, are investigated using classic electrochemical methods, respectively. Only the product, hydroxypivalic acid is detected by high performance liquid chromatography (HPLC). It can be conferred that the electrochemical oxidation of hydroxypivalaldehyde consists of two successive one-electron irreversible reactions at glass carbon (GC) electrode and the possible reaction mechanism in the ILs is proposed firstly. The diffusion coefficients of hydroxypivalaldehyde are obtained according to the electrochemical characteristics of hydroxypivalaldehyde in C4MIMPF6, C4MIMBF4 and CsMIMPF6.  相似文献   
85.
A new amperometric biosensor for hydrogen peroxide was developed based on adsorption of horseradish peroxidase at the glassy carbon electrode modified with zinc oxide nanoflowers produced by electrodeposition onto multi-walled carbon nanotubes (MWNTs) film. The morphology of the MWNTs/nano-ZnO electrode has been investigated by scanning electron microscopy (SEM), and the electrochemical performance of the electrode has also been studied by amperometric method. The resulting electrode offered an excellent detection for hydrogen peroxide at -0.11 V with a linear response range of 9.9×10^-7 to 2.9×10^-3 mol/L with a correlation coefficient of 0.991, and response time 〈5 s. The biosensor displays rapid response and expanded linear response range, and excellent stability.  相似文献   
86.
~~Formation of α,α'-Bis(substituted benzylidene)cycloalkanones from Masked Aldehydes Promoted by Samarium(III) Triiodide~~  相似文献   
87.
Great attention is currently paid to the synthesis of polynuclear transition metal complexes as well as their photochemical, photophysical, and electrochemical properties. The design of multicomponent systems capable of performing useful light- and/or redox-induced function is of special interest1. The oxo-centered carboxylate-bridge trinuclear ruthenium clusters have been investigated extensively during recent decades because they have remarkable electron-transfer properties, intense visibl…  相似文献   
88.
IBONACCISEQUENCEANDCANTOR′STERNARYSETTONGJINGCHENGSAMONS,J.ManuscriptreceivedSeptember12,1994.RevisedDecember15,1996.Depar...  相似文献   
89.
在C60单晶(111)解理面上制备出厚度约30 nm的K3C60单晶膜.利用同步辐射光源,在低温下(约150K)测量了样品法向发射的角分辨光电子谱.观察到K3C60导带和价带明显的色散.导带的光电子谱峰可清晰分辨出4个子峰,这些子峰的最大色散超过0.5eV,并且色散曲线与K3C60的一维无序晶体结构模型下的能带理论基本吻合,只是子带间隔差异较大.  相似文献   
90.
New type of spherical pore Al alloy foam with low porosity and high strength   总被引:15,自引:0,他引:15  
The Ultra Light Metal Structure with variouskinds of pores (open, close) realizes the lightness andmultifunction of structural material. The functionsinclude lightness (ρ < 1), high specific strength, highenergy absorption, sound insulation, heat insulationand electromagnetism shield. It is one of the hotspotsin material research nowadays[1— . The requirements 6]of high speed movement and high technology make Alalloy foam, which has higher specific st…  相似文献   
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