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81.
82.
N. Kent Dalley Jerald S. Bradshaw Xiaolan Kou Reed M. Izatt Krzysztof E. Krakowiak 《Journal of heterocyclic chemistry》1995,32(4):1201-1204
The solid state structure of the Na[2.2.2]C1 · 3H2O complex has the sodium ion displaced towards one of the cryptand nitrogens and the chloride and water molecules associated by hydrogen bonds to form a pseudo cube with two chloride ions at opposite corners of the cube and water oxygens at the other six corners. 相似文献
83.
B. Cameron Reed 《Central European Journal of Physics》2005,3(1):1-7
The ground-state energy of neutral helium is estimated variationally with a trial wavefunction of the form ϕ≈e
−γ(rA/a
o)ne−γ(rB/a
o)n. This model represents a modification of traditional textbook examinations of this problem via inclusion of the power “n”
as a second nonlinear variational parameter in addition to the usual effective nuclear charge γ and leads to an upper-limit
on the ground state energy of −2.86107 E
h
(E
h
=1 hartree) in comparison with the traditional (n=1) result of −2.84766 E
h
. This result represents a reduction of the percentage overestimate from the true ground-state energy (−2.90373 E
h
) of from 1.93 to 1.47. In comparison with the maximum accuracy obtainable from an uncorrelated trial wavefunction, −2.86168
E
h
, the present trial wavefunction reduces the percentage overestimate from 0.49 (n=1) to 0.021. The optimum values of (n, γ)
are determined to be ≈(0.897, 1.825). 相似文献
84.
William P. Reed 《Fresenius' Journal of Analytical Chemistry》1995,352(1-2):250-254
The global recognition that quality is an economic issue is requiring analytical chemists to look at the chemical measurement process in a way that has not been done before. Much work has been done in certifying reference materials, writing measurement protocols, creating measurement networks, developing analytical measurement techniques and other efforts to make good measurements. This article explores the meaning of quality in chemical measurements and discusses quality in terms of credibility, reliability, traceability and comparability. The importance of understanding the contribution of comparability and traceability to quality in chemical measurements and chemical metrology is emphasized. 相似文献
85.
We compare Aut(Q), the classical automorphism group of a countable dense linear order, with Aut
c
(Q), the group of all computable automorphisms of such an order. They have a number of similarities, including the facts that every element of each group is a commutator and each group has exactly three nontrivial normal subgroups. However, the standard proofs of these facts in Aut(Q) do not work for Aut
c
(Q). Also, Aut(Q) has three fundamental properties which fail in Aut
c
(Q): it is divisible, every element is a commutator of itself with some other element, and two elements are conjugate if and only if they have isomorphic orbital structures. 相似文献
86.
Reed M. Izatt Don W. McBride James J. Christensen Jerald S. Bradshaw Glen A. Clark 《Journal of membrane science》1985,22(1):31-46
Carrier-mediated cation fluxes were determined using a H2OCHC13H2O liquid merebrane system for TlNO3 and for binary mixtures of either TlNO3 or KNO3 with alkali metal ions, alkaline earth metal ions, and Pb2+ (in the case of TlNO3). Both macrocyclic polyether and cryptand ligands were used as carriers. In Tl+Mn+ mixtures, selective transport of Tl+ was found over all cations studied, except in the cases of Ag+ by 2.2 and of Pb2+ by 18C6, DC18C6, ClDKP18C6, and 2.2. Generally, K+ was transported selectively from K+Mn+ mixtures, except in the cases of K+Tl+ mixtures in which Tl+ was transported selectively in all cases. A model relating cation flux to log K(CH3OH) for Mn+—macrocycle interaction and to ion-partitioning between the organic and aqueous phases was successful in rationalizing selective cation transport in most of the systems studied. 相似文献
87.
Recent Gaussian-effective-potential results for “autonomous”λΦ 4 theory, an apparently nontrivial, positive-λ, 3+1 dimensional theory, are extended to include a Yukawa coupling to fermions. The formerly massless bosons of the symmetric phase acquire a mass. 相似文献
88.
89.
By extending Kato's theory of two Hilbert space scattering, we are able to formulate both optical and accoustical scattering from inhomogeneous media as strictly elliptic problems. We use this formulation to present simple proofs of the existence and completeness of scattering states. 相似文献
90.