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691.
692.
From dispersity studies and adsorption isotherms on alumina supported Ir, Ir–Pt and Ir–Pd catalysts, the ratios of O/M=1 and CO/M=1 are obtained. Electron microscopiec results agree with chemisorption data.
Ir, Ir–Pt Ir–Pd, , O/M=1 CO/M=1. - .相似文献
693.
694.
In the Br?nsted superacid CF(3)SO(3)H (triflic acid), amides are able to form reactive, dicationic electrophiles. It is shown that these dicationic intermediates participate in two distinctly different types of electrophilic reactions. The protonated amide increases the reactivity of an adjacent electrophilic group, and the protonated amide group itself shows enhanced reactivity arising from an adjacent cationic charge. In the latter case, several types of amides are even capable of reacting with benzene by Friedel-Crafts acylation. [reaction--see text] 相似文献
695.
Dimitrios?C.?KyritsisEmail author Vito?S.?Santoro Alessandro?Gomez 《Experiments in fluids》2004,37(5):769-772
The temperature dependent corrections of the formaldehyde laser induced fluorescence raw signal are discussed for the 355 nm excitation, which is widely available as the third harmonic of Nd-YAG lasers. The temperature dependence of the HCHO partition function is calculated explicitly and the effect of quenching corrections is discussed in view of the absence of experimental data on collision cross-sections. Particular reference is made to the case of HCHO layers in hydrocarbon diffusion flames. It is shown that the thickness of such layers is not affected drastically by the calculated corrections, which has implications for the estimate of the scalar dissipation rate in diffusion flames. 相似文献
696.
Zheng X Aniol K Armstrong DS Averett TD Bertozzi W Binet S Burtin E Busato E Butuceanu C Calarco J Camsonne A Cates GD Chai Z Chen JP Choi S Chudakov E Cusanno F Leo RD Deur A Dieterich S Dutta D Finn JM Frullani S Gao H Gao J Garibaldi F Gilad S Gilman R Gomez J Hansen JO Higinbotham DW Hinton W Horn T De Jager CW Jiang X Kaufman L Kelly J Korsch W Kramer K LeRose J Lhuillier D Liyanage N Margaziotis DJ Marie F Markowitz P McCormick K Meziani ZE Michaels R Moffit B Nanda S Neyret D Phillips SK 《Physical review letters》2004,92(1):012004
We have measured the neutron spin asymmetry A(n)(1) with high precision at three kinematics in the deep inelastic region at x=0.33, 0.47, and 0.60, and Q(2)=2.7, 3.5, and 4.8 (GeV/c)(2), respectively. Our results unambiguously show, for the first time, that A(n)(1) crosses zero around x=0.47 and becomes significantly positive at x=0.60. Combined with the world proton data, polarized quark distributions were extracted. Our results, in general, agree with relativistic constituent quark models and with perturbative quantum chromodynamics (PQCD) analyses based on the earlier data. However they deviate from PQCD predictions based on hadron helicity conservation. 相似文献
697.
Stoeva Z Gomez R Gordon AG Allan M Gregory DH Hix GB Titman JJ 《Journal of the American Chemical Society》2004,126(13):4066-4067
The structure, Li+ diffusion dynamics, and magnetic properties of the layered nitridonickelate(II), LiNiN, have been investigated by powder X-ray diffraction, 7Li solid-state NMR, and SQUID magnetometry and compared and contrasted with those of the Li+ fast ion conductor, Li3N. The replacement of Li+ by Ni2+ with concomitant generation of Li+ vacancies has profound effects on ionic diffusion and electronic properties. The nitridonickelate, akin to its binary parent, displays rapid Li+ ion diffusion but, by contrast, the diffusion process is confined only to the Li-N planes. Further, replacement of Li by Ni leads to a transition from semiconducting to metallic behavior, likely mediated through the creation of infinite, 1D Ni-N chains of increased covalency. 相似文献
698.
A graphical method for measuring derivative amplitudes in binary mixtures with overlapping spectra is described. The method is based on the interference-free character of the isodifferential points in the derivative calibration graphs. Cobalt and nickel mixtures are analyzed in the range 0.01–2.5 μg ml?1 by the formation of coloured chelates with benzyl-2-pyridylketone 2-pyridylhydrazone, with relative standard deviations ?1.5%. 相似文献
699.
[reaction: see text] The alpha-arylation of the zinc enolate of N-protected 2-piperidinones with aryl bromides in the presence of a palladium catalyst is described as a general method. 相似文献
700.
Strauch S Dieterich S Aniol KA Annand JR Baker OK Bertozzi W Boswell M Brash EJ Chai Z Chen JP Christy ME Chudakov E Cochran A De Leo R Ent R Epstein MB Finn JM Fissum KG Forest TA Frullani S Garibaldi F Gasparian A Gayou O Gilad S Gilman R Glashausser C Gomez J Gorbenko V Gueye PL Hansen JO Higinbotham DW Hu B Hyde-Wright CE Ireland DG Jackson C de Jager CW Jiang X Jones C Jones MK Kellie JD Kelly JJ Keppel CE Kumbartzki G Kuss M LeRose JJ Livingston K Liyanage N Malov S Margaziotis DJ 《Physical review letters》2003,91(5):052301
We have measured the proton recoil polarization in the 4He(e-->,e(')p-->)4H reaction at Q(2)=0.5, 1.0, 1.6, and 2.6 (GeV/c)(2). The measured ratio of polarization transfer coefficients differs from a fully relativistic calculation, favoring the inclusion of a medium modification of the proton form factors predicted by a quark-meson coupling model. In addition, the measured induced polarizations agree reasonably well with the fully relativistic calculation indicating that the treatment of final-state interactions is under control. 相似文献