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251.
The analysis of spin-lattice relaxation (SLR) of very dilute impurity nuclei in ferromagnetic hosts, as encountered in NMR
of oriented nuclei (NMRON), usually neglects the spin-spin interaction, assuming a no-spin-temperature model. However, the
regime of impurity systems for which this assumption is valid has not been established. the relaxation following single passage
in60CoFe<110> and55CoFe<100> has been measured, and is compared with calculations made with and without a spin-temperature constraint. 相似文献
252.
253.
I. Ahmad S.M. Austin B.B. Back R.R. Betts F.P. Calaprice K.C. Chan A. Chishti P. Chowdhury C. Conner R.W. Dunford J.D. Fox S.J. Freedman M. Freer S.B. Gazes A.L. Hallin T. Happ D. Henderson N.I. Kaloskamis E. Kashy W. Kutschera J. Last C.J. Lister M. Liu M.R. Maier D.J. Mercer D. Mikolas P.A.A. Perera M.D. Rhein E. Roa J.P. Schiffer T.A. Trainor P. Wilt J.S. Winfield M. Wolanski F.L.H. Wolfs A.H. Wuosmaa A. Young J.E. Yurkon 《Zeitschrift für Physik A Hadrons and Nuclei》1997,358(2):235-236
254.
255.
The rate constant for abstraction of hydrogen from isobutane by methyl radicals has been re-examined making use of new measurements at temperatures above 660 K. Most of the data over the temperature range 300–855 K can be accommodated by the following values for the rate constants for abstraction from primary and tertiary hydrogen atoms: This activation energy for abstraction of the tertiary hydrogen atom in isobutane is essentially the same as expressed in a previous evaluation, which considered data only below 500 K, but the magnitude of the rate constant is about 0.25 log units greater. 相似文献
256.
257.
Replacement of the 2-keto group of readily available di(endo-3-camphoryl) diselenide with oxime or O-benzoyloxime substituents, followed by conversion into the corresponding selenenyl triflates, produced highly effective chiral selenium electrophiles for the asymmetric oxyselenenylation of alkenes in the presence of methanol. 相似文献
258.
259.
Conformationally restricted naphthalene peri-diselenides function as glutathione peroxidase mimetics with superior catalytic activity to that displayed by typical acyclic diaryl diselenides. Their activity was increased by electron-donating methoxy substituents, while a further 100-fold increase was observed with the corresponding ditelluride. 相似文献
260.
Determination of f(s)/f(d) for 7 TeV pp collisions and measurement of the B0→D-K+ branching fraction
Aaij R Adeva B Adinolfi M Adrover C Affolder A Ajaltouni Z Albrecht J Alessio F Alexander M Alkhazov G Alvarez Cartelle P Alves AA Amato S Amhis Y Amoraal J Anderson J Appleby RB Gutierrez OA Arrabito L Artamonov A Artuso M Aslanides E Auriemma G Bachmann S Back JJ Bailey DS Balagura V Baldini W Barlow RJ Barschel C Barsuk S Barter W Bates A Bauer C Bauer T Bay A Bediaga I Belous K Belyaev I Ben-Haim E Benayoun M Bencivenni G Benson S Benton J Bernet R Bettler MO van Beuzekom M Bien A Bifani S 《Physical review letters》2011,107(21):211801
The relative abundance of the three decay modes B(0)→D(-)K(+), B(0)→D(-)π(+), and B(s)(0)→D(s)(-)π(+) produced in 7 TeV pp collisions at the LHC is determined from data corresponding to an integrated luminosity of 35 pb(-1). The branching fraction of B(0)→D(-)K(+) is found to be B(B(0)→D(-)K(+)) = (2.01 ± 0.18(stat) ± 0.14(syst)) × 10(-4). The ratio of fragmentation fractions f(s)/f(d) is determined through the relative abundance of B(s)(0)→D(s)(-)π(+) to B(0)→D(-)K(+) and B(0)→D(-)π(+), leading to f(s)/f(d) = 0.253 ± 0.017 ± 0.017 ± 0.020, where the uncertainties are statistical, systematic, and theoretical, respectively. 相似文献