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271.
We use the reference interaction site model (RISM) integral equation theory to study the percolation behavior of fluids composed of long molecules. We examine the roles of hard core size and of length-to-width ratio on the percolation threshold. The critical density c is a nonmonotonic function of these parameters exhibiting competition of different effects. Comparisons with Monte Carlo calculations of others are reasonably good. For critical exponents, the theory yields =2=2 for molecules of any noninfinite lengthL. WhenL is very large, the theory yields cL
–2. These predictions compare favorably with observations of the conductivity for random assemblies of conductive fibers. The threshold region where asymptotic scaling holds requires the correlation length (/
c
)
–v
to be much larger thanL. Evidently, the range of densities in this region diminishes asL increases, requiring that density deviations from c be no larger thanL
–2. Otherwise, crossover behavior will be observed. 相似文献
272.
273.
Inside Back Cover: Total Synthesis and Conformational Study of Callyaerin A: Anti‐Tubercular Cyclic Peptide Bearing a Rare Rigidifying (Z)‐2,3‐ Diaminoacrylamide Moiety (Angew. Chem. Int. Ed. 14/2018)
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278.
A. O. Bazarko C. G. Arroyo K. T. Bachmann T. Bolton C. Foudas B. J. King W. C. Lefmann W. C. Leung S. R. Mishra E. Oltman P. Z. Quintas S. A. Rabinowitz F. J. Sciulli W. G. Seligman M. H. Shaevitz F. S. Merritt M. J. Oreglia B. A. Schumm R. H. Bernstein F. Borcherding H. E. Fisk M. J. Lamm W. Marsh K. W. B. Merritt H. M. Schellman D. D. Yovanovitch A. Bodek H. S. Budd P. de Barbaro W. K. Sakumoto T. Kinnel P. H. Sandler W. H. Smith 《Zeitschrift fur Physik C Particles and Fields》1995,65(2):189-198
We present the first next-to-leading-order QCD analysis of neutrino charm production, using a sample of 6090
– and
-induced opposite-sign dimuon events observed in the CCFR detector at the Fermilab Tevatron. We find that the nucleon strange quark content is suppressed with respect to the non-strange sea quarks by a factor =0.477
–0.053
+0.063
, where the error includes statistical, systematic and QCD scale uncertainties. In contrast to previous leading order analyses, we find that the strange seax-dependence is similar to that of the non-strange sea, and that the measured charm quark mass,m
c
=1.70±0.19 GeV/c2, is larger and consistent with that determined in other processes. Further analysis finds that the difference inx-distributions betweenxs(x) and
is small. A measurement of the Cabibbo-Kobayashi-Maskawa matrix element |V
cd
|=0.232
–0.020
+0.018
is also presented. 相似文献
279.
Partial Difference Sets with Paley Parameters 总被引:2,自引:0,他引:2
Partial difference sets with parameters (,k,,µ) = (,( 1)/2, ( 5)/4,( 1)/4) are called Paleypartial difference sets. By using finite local rings, we constructa family of Paley PDSs for abelian p-groups with any given exponent.Furthermore, we prove some non-existence results on Paley PDSs.Using these results, we prove that Paley PDSs exist in a rank2 abelian group if and only if the group is isomorphic to Zpr x Zp r where p is an odd prime. 相似文献
280.
The anion [Au2(CS3)2]2- has an unusually short Au-Au distance (2.80 A) for a binuclear Au(I) complex. We report detailed Raman studies of the nBu4N+ salt of this complex, including FT-Raman of the solid and UV/vis resonance Raman of dimethyl sulfoxide solutions. All five totally symmetric vibrations of the anion have been located and assigned. A band at delta nu = 125 cm-1 is assigned to nu (Au2). The visible-region electronic absorption bands (384 (epsilon 30,680) and 472 nm (epsilon 610 M-1 cm-1)) are attributable to CS3(2-) localized transitions, as confirmed by the dominance of nu sym(C-Sexo) (delta nu = 951 cm-1) in RR spectra measured in this region. An absorption band at 314 nm (22,250 M-1 cm-1) is assigned as the metal-metal 1(d sigma*-->p sigma) transition, largely because nu sym(C-Sexo) is not strongly enhanced in RR involving this band. Observation of the expected strong resonance enhancement of nu (Au2) was precluded as a result of masking by intense solvent Rayleigh scattering in the UV. 相似文献