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151.
Jetti RK Thallapally PK Nangia A Lam CK Mak TC 《Chemical communications (Cambridge, England)》2002,(9):952-953
The title molecule forms a honeycomb network of molecular and nitro-trimer synthons with guest species included in the hexagonal voids. 相似文献
152.
153.
154.
Let P be a lattice polytope in R
n
, and let P \cap Z
n
= {v
1
,\ldots,v
N
} . If the N + N\choose 2 points 2v
1
,\ldots, 2v
N
;v
1
+v
2
,\ldots, v
N-1
+ v
N
are distinct, we say that P is a ``distinct pair-sum' or ``dps' polytope. We show that if P is a dps polytope in R
n
, then N≤ 2
n
, and, for every n , we construct dps polytopes in R
n
which contain 2
n
lattice points. We also discuss the relation between dps polytopes and the study of sums of squares of real polynomials.
Received November 10, 2000, and in revised form June 28, 2001. Online publication November 2, 2001. 相似文献
155.
156.
157.
Wing Tsang 《国际化学动力学杂志》1978,10(1):41-66
Tertiary-amyl amine has been decomposed in single-pulse shock-tube experiments. Rate expressions for several of the important primary steps are This leads to D(CH3? H) – D(NH2? H) = ?10.5 kJ and D[(CH3)3C? H] – D[(CH3)2NH2C? H] = + 6 kJ. The present and earlier comparative rate single-pulse shock-tube data when combined with high-pressure hydrazine decomposition results-(after correcting for fall off effects through RRKM calculations) gives where kr(…) is the recombination rate involving the appropriate radicals. This suggests that in this context amino radical behavior is analogous to that of alkyl radicals. If this agreement is exact, then Rate expressions for the primary step in the decomposition of a variety of primary amines have been computed. In the case of benzyl amine where data exist the agreement is satisfactory. The following differences in bond energies have been estimated: 相似文献
158.
Wing Tsang 《国际化学动力学杂志》1978,10(6):599-617
Cyclopentane has been decomposed in comparative-rate single-pulse shock-tube experiments. The pyrolytic mechanism involves isomerization to 1-pentene and also a minor pathway leading to cyclopropane and ethylene. This is followed by the decomposition of 1-pentene and cyclopropane. The rate expressions over the temperature range of 1000°–1200° K are Details of the cyclopentane decomposition processes are considered, and it appears that if the trimethylene radical is an intermediate, then ΔHf(trimethylene) ≤ 280 kJ/mol at 300°K. 相似文献
159.
A formalism is proposed for treating the problem of ionization of adsorbed species on solid surfaces. The ionizing agents are taken to be impact atoms and laser radiation with frequency low compared to the inverse of characteristic collision times. The physical constraints of short collision times and low laser frequency then allow one to treat the adatom-surface-plus-field system under the quasi-static approximation (QSA) and the impact-atom-adatom-surface collision dynamics under the impulse approximation (IMA). The latter leads to a time-dependent ionization cross-section which is factorizable into the square of an electron-atom scattering matrix element and a spectral function describing the energy-momentum distribution of electrons in the adatom-surface-plus-field system. The formalism focuses on the spectral function which is shown to be derivable from a single-particle Green's function exactly calculable for the present problem. 相似文献
160.