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排序方式: 共有193条查询结果,搜索用时 4 毫秒
51.
Comely AC Gibson SE Hales NJ Johnstone C Stevenazzi A 《Organic & biomolecular chemistry》2003,1(11):1959-1968
Carbonylcobalt(0) species have been used as linkers between alkynes and a polymer support for the first time. The alkynes may be loaded indirectly onto a phosphine functionalised polymer via their hexacarbonyldicobalt(0) complex, or directly onto a cobalt coated polymer. The alkynes have been released either as alkynes, thus providing a traceless method of immobilising alkynes, or by reaction with an alkene to generate a cyclopentenone via the Pauson-Khand reaction. The cobalt coated polymers produced during this study were shown to catalyse the Pauson-Khand reaction. 相似文献
52.
Hydrogen isotope studies have shown that heterogeneous catalytic transfer hydrogenolysis of C-O bonds in tetrazolyl ethers of phenols (1) in the liquid phase proceeds via direct transfer of hydrogen from an active hydrogen donor centre to the ether on the catalyst surface and not through transfer of hydrogen atoms from the catalyst surface. 相似文献
53.
A new approach to functionalized spiropiperidines through tandem RCM and nitrogen-directed reactions
Edwards AS Wybrow RA Johnstone C Adams H Harrity JP 《Chemical communications (Cambridge, England)》2002,(14):1542-1543
The synthesis of a functionalized spiropiperidine via a tandem ring closing metathesis strategy is described, furthermore, the regio- and stereoselective functionalization of this compound has been achieved through a novel nitrogen-directed epoxidation reaction. 相似文献
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OK Yoon WG Hwang JC Choe MS Kim 《Rapid communications in mass spectrometry : RCM》1999,13(14):1515-1521
A technique to investigate photodissociation kinetics on a nanosecond time scale has been devised for molecular ions generated by multiphoton ionization (MPI) using mass-analyzed ion kinetic energy spectrometry. The branching ratio or rate constant has been determined for the photodissociation of the n-butylbenzene, bromobenzene, iodobenzene, and aniline molecular ions generated by MPI at 266 nm. The ion internal energies have been estimated by comparing the measured kinetic data with the previous energy dependence data. The analysis has shown that only those molecular ions generated by two-photon ionization contribute to the photodissociation signals. Around half of the available energy has been found to remain as molecular ion internal energy in the two-photon ionization process. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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B.M. Barnett W. Gyles R.R. Johnson K.L. Erdman J. Johnstone J.J. Kraushaar S. Lepp T.G. Masterson E. Rost D.R. Gill A.W. Thomas J. Alster I. Navon R.H. Landau 《Physics letters. [Part B]》1980,97(1):45-49
A new method using low energy π+ elastic scattering is employed to determine the proton matter distribution of a nucleus relative to an adjacent nucleus differing by one proton. The difference in the rms charge radii of 12C and 11B was determined to be 0.072 ± 0.021 fm with π+ beam energies of 38.6 and 47.7 MeV. 相似文献
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I.W. Johnstone D.J. Lockwood M.W.C. Dharma-wardana 《Solid State Communications》1980,36(12):1033-1037
Light scattering from magnons in CsCoBr3 has been measured for temperatures well below the upper antiferromagnetic 3D ordering temperature of TlN = 28 K. These experiments reveal multiple magnon features of energies in the range 90 to 170 cm-1 similar to those found in CsCoCl3 but previously unobserved for the bromide. Prominent features in the spectrum and their temperature dependence are described in terms of a recent theory by Shiba. Other, weaker features are explained by a simple extension of the theory to include fluctuations. A new band is observed at 178 cm-1, whose intensity drops sharply prior to the lower 3D ordering transition at T∥N = 10 K. This band is assigned to magnon-phonon combination scattering. 相似文献