排序方式: 共有32条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
Lucie Loukotková Eva Tesařová Zuzana Bosáková Pavel Repko Daniel W. Armstrong 《Journal of separation science》2010,33(9):1244-1254
Retention and enantioseparation behavior of ten 2,2′‐disubstituted or 2,3,2′‐trisubstituted 1,1′‐binaphthyls and 8,3′‐disubstituted 1,2′‐binaphthyls, which are used as catalysts in asymmetric synthesis, was investigated on eight chiral stationary phases (CSPs) based on β‐CD, polysaccharides (tris(3,5‐dimethylphenylcarbamate) cellulose or amylose CSPs) and new synthetic polymers (trans‐1,2‐diamino‐cyclohexane, trans‐1,2‐diphenylethylenediamine and trans‐9,10‐dihydro‐9,10‐ethanoanthracene‐(11S,12S)‐11,12‐dicarboxylic acid CSPs). Normal‐, reversed‐phase and polar‐organic separation modes were employed. The effect of the mobile phase composition was examined. The enantiomeric separation of binaphthyl derivatives, which possess quite similar structures, was possible in different enantioselective environments. The substituents and their positions on the binaphthyl skeleton affect their properties and, as a consequence, the separation system suitable for their enantioseparation. In general, the presence of ionizable groups on the binaphthyl skeleton, substitution with non‐identical groups and a chiral axis in the 1,2′ position had the greatest impact on the enantiomeric discrimination. The 8,3′‐disubstituted 1,2′‐binaphthyl derivatives were the most easily separated compounds in several separation systems. From all the chiral stationary phases tested, cellulose‐based columns were shown to be the most convenient for enantioseparation of the studied analytes. However, the polymeric CSPs with their complementary behavior provided good enantioselective environments for some derivatives that could be hardly separated in any other chromatographic system. 相似文献
7.
Results for the one-loop calculation of the decay width Γ(H→ggZ) in the standard model with Higgs boson masses in the range 115 GeV<m
H
<2m
W
are presented. We find that among all the helicity amplitudes contributing to the width only those for which the gluons have
the same polarization and the Z is longitudinally polarized contribute in any significant way. The calculation includes all contributions from the second
and third generations, and kinematic cuts to enhance the H→ggZ signal. Compared to the width of H→gg, we find Γ(H→ggZ)/Γ(H→gg)≲10−4. 相似文献
8.
The residual Z(2)(s)(k) and Z(2)(s)(k) symmetries induce a direct and unique phenomenological relation with θx (≡ θ13) expressed in terms of the other two mixing angles θs(≡ θ12) and θa(≡ θ23) and the Dirac CP phase δD. Z(2)(s)(k) predicts a θx probability distribution centered around 3°-6° with an uncertainty of 2°-4°, while those from Z(2)(s)(k) are approximately a factor of 2 larger. Either result fits the T2K, MINOS, and Double Chooz measurements. Alternately, a prediction for the Dirac CP phase δD results in a peak at ± 74° (± 106°) for Z(2)(s)(k) or ± 123° (± 57°) for Z(2)(s)(k) which is consistent with the latest global fit. We also give a distribution for the leptonic Jarlskog invariant Jν which can provide further tests from measurements at T2K and NOνA. 相似文献
9.
10.