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101.
102.
Hydrogen bonding and the electron-withdrawing or electron-donating characteristics of substituent groups that are neighboring to epoxide groups can affect the reactivity of the epoxide ring. The crystal structure ofcis-2,3-epoxycyclooctanol has been determined as a saturated eight-membered ring compound in which a hydroxyl group is attached to the C(1) atom that is adjacent to a 2,3-fused epoxy ring. The findings are that the longer epoxide C-O bond (and hence the one expected to be more readily broken) is the one farther from the hydroxyl group [1.462(1) å versus 1.447(1) å] and that the optimal hydrogen bonding is to an adjacent molecule radier than within the molecule. The shortest C-C bond is that of the epoxide group; the bond adjacent to it (on the side farther from the hydroxyl group) is the next shortest. 相似文献
103.
104.
Marym Lashanizadehgan Mehdi Rashidi Janet E. Hux Richard J. Puddephatt Samson S.M. Ling 《Journal of organometallic chemistry》1984,269(3):317-322
Reaction of excess MeLi and MeI with [PtCl2SMe2)2] gives the first binuclear tetramethylplatinum(IV) complex [Pt2Me8(μ-SMe2)2]. The characterization of this complex, and its reactions with donor ligands to give cis-[PtMe4L2] (L2 = Ph2PCH2PPh2, Ph2PCH2CH2PPh2, 2,2′-bipyridyl, 1,10-phenanthroline or L = PMe2Ph, PMePh2) are described. 相似文献
105.
C. Budtz-Jørgensen P. Guenther A. Smith J. Whalen W. R. McMurray M. J. Renan I. J. van Heerden 《Zeitschrift für Physik A Hadrons and Nuclei》1984,319(1):47-56
Neutron total, scattering and (n; n′,γ) cross sections of elemental yttrium (89Y) were measured in the few-MeV region. The neutron total-cross-section measurements were made with broad resolutions from ≈0.5 to 4.2MeV in steps of ?0.1 MeV. Neutron elastic- and inelastic-scattering cross sections were measured from ≈1.5 to 4.0 MeV, at incident-neutron energy intervals of ≈50keV and at ten or more scattering angles distributed between 20 and 160 degrees using neutron detection. Inelastic-scattering cross sections were also determined using the (n; n′,γ) reaction at incident energies from 1.6 to 3.8 MeV at intervals of 0.1 MeV. Gamma-rays and/or inelastically-scattered neutrons were observed corresponding to the excitation of levels at: 909.0±0.5, 1,507.4 ±0.3, 1,744.5±0.3, 2,222.6±0.5, 2,530±0.8, 2,566.4±1.0, 2,622.5±1.0, 2,871.9 ±1.5, 2,880.6±2.0, 3,067.0±2.0, 3,107.0±2.0, 3,140.0±2.0, 3,410.0±2.0, 3,450.0±2.0, 3,504.0 ±1.5, 3,514.0±2.0, 3,556.0±2.0, 3,619.0±3.0, 3,629.0±3.0 and 3,715.0±3.0 keV. The experimental results are discussed in terms of the spherical-optical-statistical, coupledchannels, and core-coupling models, and in the context of previously reported excitedlevel structure. 相似文献
106.
Matrices of bisimple regular semigroups 总被引:1,自引:0,他引:1
Janet E. Mills 《Semigroup Forum》1983,26(1):117-123
A semigroup S is a matrix of subsemigroups Siμ, i ε I, μ ε M if the Siμ form a partition of S and SiμSjν≤Siν for all i, j in I, μ, ν in M. If all the Siμ are bisimple regular semigroups, then S is a bisimple regular semigroup. Properties of S are considered when the Siμ are bisimple and regular; for example, if S is orthodox then each element of S has an inverse in every component Siμ. 相似文献
107.
Translational hull of an inverse semigroup 总被引:1,自引:0,他引:1
Janet E. Ault 《Semigroup Forum》1972,4(1):165-168
The theory of ideal extensions of semigroups is dependent upon adequate knowledge of the translational hull. We characterize
here certain basic structures in the translational hull, Ω(S), of an arbitrary inverse semigroup S: in particular, the semilattice
of idempotents of Ω(S) and the group of units of Ω(S). An isomorphic copy of each of these structures is given in terms of
the semilattice of idempotents of S. 相似文献
108.
109.
It is known that compliance scheme does not provide simple linear isotopic sum rules in λ?1 similar to the ones in λ in the force constant scheme. The advantage of not having such sum rules in the compliance scheme is discussed in relation to the uniqueness problem of the molecular force field.Incidentally, for the molecules H2O, D2O, and HDO, two quadratic relations in terms of the inverse frequency parameters λ?1 are obtained. These supplement the three obvious product rule relations. 相似文献
110.
Janet E. Jones 《Annals of Physics》1976,101(2):380-393
It is shown for the case of a conformally flat vacuum that the curvature of space-time may be viewed as the observable consequence of particle interactions involving a scalar field φ, rather than the independent agency of the gravitational field by itself. The quantum nature of gravity comes in as a consequence of the quantum properties of the φ-field (“vacuum fluctuation”), and a direct analogy is drawn between the renormalizations of charge and mass. Cosmological solutions are derived: These being just the conventional Friedmann solutions, or the de Sitter solution. It is pointed out that a totally empty universe must be Minkowskian. 相似文献