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排序方式: 共有893条查询结果,搜索用时 15 毫秒
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795.
van der Vlugt JI Rauchfuss TB Whaley CM Wilson SR 《Journal of the American Chemical Society》2005,127(46):16012-16013
Reduction of diferrous dithiolato complexes with hydride donor reagents affords the first example of the previously elusive terminal diferrous hydride, [Fe2(edt)(mu-CO)(H)(CO)(PMe3)4]PF6 (edt = S2C2H4). Crystallographic characterization shows that this model contains an asymmetrical semi-bridging CO trans to a terminal hydrido, as indicated in the Hred state in the D. desulfuricans enzyme. The model reacts with protons to yield H2 and rearranges via an intramolecular process to the isomeric mu-hydrido isomer, which is unreactive toward protons. 相似文献
796.
热致液晶高分子微纤的形貌特征和一个模量分析的方法 总被引:2,自引:0,他引:2
热致液晶高分子微纤的形貌特征和一个模量分析的方法益小苏,沈烈(浙江大学高分子科学与工程学系,杭州,310027)关键词热致液晶高分子,原位复合,弹性模量,注塑由于主链型热致液晶高分子(LCP)的高模量、高强度、易取向、低粘度等特性,当将这种高分子以较... 相似文献
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798.
Summary The fluorescence reaction using the catalytic effect of horse radish peroxidase on the oxidation of tyrosine by hydrogen peroxide has been investigated. The reaction product fluoresces at 412 nm (excitation at 316 nm). Microamounts of hydrogen peroxide and tyrosine can be determined with good accuracy and reproducibility. The proposed method has been used to determine glucose and tyrosine in human serum. The results are satisfactory. The characteristics of tyrosine have been compared with those of homovanillic acid in the enzyme-catalysed reaction system.
Peroxidase-katalysierte Fluorescenzreaktion mit Tyrosin als Substrat相似文献
799.
Orita A Nakano T An DL Tanikawa K Wakamatsu K Otera J 《Journal of the American Chemical Society》2004,126(33):10389-10396
Pyridine-containing arylene ethynylene strands were connected to the 2- and 2'-positions of (R)- and (S)-1,1'-binaphthyl templates. The arylene ethynylene moieties underwent intramolecular coordination with Ag(I) or Cu(I) ion to afford enantiopure double helicates. The double-helical structure was elucidated on the basis of circular dichroic (CD) spectra. The importance of intramolecular complexation of the double strands for the helicate formation was confirmed by comparison with a ligand bearing a single strand. Connection of the strands through an ether linkage enabled a sorting out of the Cotton effect induced by double-helical arylene ethynylene moieties. The CD exciton chirality method unambiguously proved that the termini of the strands approach each other upon complexation and that the sense of the induced helicity is the same as predicted by molecular modeling. 相似文献
800.
Ruben vanDuren LeandraL.J.M. Cornelissen JarlIvar vanderVlugt JeroenP.J. Huijbers AllisonM. Mills AnthonyL. Spek Christian Müller Dieter Vogt 《Helvetica chimica acta》2006,89(8):1547-1558
The chiral diphosphonite ligand (11bR,11′bR)‐4,4′‐(9,9‐dimethyl‐9H‐xanthene‐4,5‐diyl)bis[dinaphtho[2,1‐d:1′,2′‐f][1,3,2]dioxaphosphepin] ((R,R)‐XantBino; (R)‐ 1 ), based on a rigid xanthene backbone, was applied in the Pt/Sn‐catalyzed hydroformylation of styrene ( 4a ), 4‐methylstyrene ( 4b ), vinyl acetate ( 4c ), and allyl acetate ( 4d ), by using a Pt/Sn ratio of 1 : 1. High ee of up to 80% were observed, along with good regioselectivities towards the desired branched aldehydes. For styrene, an interesting inversion in the stereoselection process was observed at elevated temperatures, and a mechanism is proposed considering the temperature dependence of the regioselectivity. The complex [PtCl2{(S,S)‐XantBino}] ((S)‐ 2 ) was characterized by X‐ray crystal‐structure analysis, revealing an unusual out‐of‐plane ligand coordination of the metal fragment. The complex [PtCl(SnCl3){(R,R)‐XantBino}] ((R)‐ 3 ) was characterized by means of 31P‐NMR spectroscopy. 相似文献