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961.
Gordon W. Rewcastle Hamish S. Sutherland Claudette A. Weir Adrian G. Blackburn William A. Denny 《Tetrahedron letters》2005,46(50):8719-8721
A novel two-step synthesis of isonitrosoacetanilides [2-(hydroxyimino)-N-phenylacetamides] has been developed, involving the initial acylation of aniline derivatives with 2,2-diacetoxyacetyl chloride, followed by reaction with hydroxylamine hydrochloride. The method works equally well with a variety of different aniline derivatives, including those with poor aqueous solubility and those containing electron rich ortho-substituents, neither of which react well under traditional conditions. 相似文献
962.
A fluoroionophore sensor, N-[4-(1-pyrene)butyroyl]-L-tryptophan (PLT), has been reported. It can distinguish lead ion from other 12 metal ions via forming a pyrene dimer and it exhibits a very high sensitivity (0.15 microM) in aqueous solution (Chem. Commun., 2006, 2702). When the indole moiety in PLT was changed to benzene, in forming a new fluoroionophore of N-[4-(1-pyrene)butyroyl]-L-phenylalanine (PLP), it could not form a pyrene dimer in response to Pb(2+) in water. The present study describes the spectroscopic clarification of the intrinsic differences of the binding model between PLP and PLT in binding with Pb(2+). The model shows identical chelating bidentate coordination between COO(-) and Pb(2+) both in PLP-Pb and PLT-Pb; however, there is no indication of the interaction between the phenyl ring and the metal ion or the hydrogen bonding between amide groups in PLP-Pb. These differences in the binding model between PLP-Pb and PLT-Pb illustrate that the indole ring in PLT appears to play a crucial role in the high selectivity and sensitivity of PLT to lead(II) ion. 相似文献
963.
We introduce a random perturbed version of the classical fidelity and we show that it converges with the same rate of decay
of correlations, but not uniformly in the noise. This makes the classical fidelity unstable in the zero-noise limit. 相似文献
964.
Neutral Community Theory: How Stochasticity and Dispersal-Limitation Can Explain Species Coexistence
Neutral community theory explains biodiversity, i.e. the coexistence of several species, as the result of a stochastic balance
between immigration and extinction on a local level, and between speciation and extinction on a regional level. The most popular
model, presented by Hubbell in 2001, has seen many analytical developments in recent years, which can be used in model analysis,
model testing and model comparison. We review these developments here, and present alternative derivations and shine previously
unnoticed lights on them. 相似文献
965.
The hyperfine constants for muonium in elemental and binary inorganic solids suggest formation of three different families
of defect centre, with distinct electronic structures. The overall range of values, spanning nearly five orders of magnitude,
and their correlation with host properties such as band gap and electron affinity, reveal a deep-to-shallow instability which
has profound implications for the electrical properties of hydrogen impurity in electronic materials, both semiconducting
and dielectric. 相似文献
966.
V. V. Lozhkarev S. G. Garanin R. R. Gerke V. N. Ginzburg E. V. Katin A. V. Kirsanov G. A. Luchinin A. N. Mal’shakov M. A. Mart’yanov O. V. Palashov A. K. Poteomkin N. N. Rukavishnikov A. M. Sergeev S. A. Sukharev G. I. Freidman E. A. Khazanov A. V. Charukhchev A. A. Shaikin I. V. Yakovlev 《JETP Letters》2005,82(4):178-180
In experiments on the parametrical amplification of femtosecond pulses in wide-aperture DKDP crystals, a power of more than 100 TW has been reached, which is much higher than the record level achieved in such lasers. The energy efficiency obtained for the parametric amplifier is equal to 27%. The energy of a 72-fs pulse is equal to 10 J. 相似文献
967.
The change in the intensity of light scattering in a colloidal solution of magnetite particles in kerosene under the simultaneous action of coaxial and mutually perpendicular electric and magnetic fields has been studied. It has been found that, at certain strengths of mutually perpendicular fields, the change in the scattering intensity is maximal. The effect observed has been interpreted on the basis of the Rayleigh-Debye-Gans anisotropic approximation within the model of orientation of aggregates of magnetite particles under the joint action of the fields. 相似文献
968.
R. Centore P. Riccio S. Fusco A. Carella A. Quatela S. Schutzmann F. Stella F. De Matteis 《Journal of polymer science. Part A, Polymer chemistry》2007,45(13):2719-2725
We have prepared new polyesters containing quadratic, nonlinear optical (NLO) active chromophores covalently incorporated into the main chain. In these polymers, the sequence of the chromophore units along the main chain is rigorously head to tail. All the polyesters are processable, both in the melt and in solution. For one polyester, a full second‐order NLO characterization has been performed. An out‐of‐resonance d33 coefficient of 21 pm/V at 1368 nm has been measured. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2719–2725, 2007 相似文献
969.
This paper deals with the small-angle neutron scattering (SANS) investigation on solution-quenched PH13-8 Mo stainless steel.
From the nature of the variation of the functionality of the profiles for varying specimen thickness and also from the transmission
electron microscopy (TEM), it has been established that the small-angle scattering signal predominantly originates from the
block-like metallic carbide precipitates in the specimen. The contribution due to double Bragg reflection is not significant
in the present case. The single scattering profile has been extracted from the experimental profiles corresponding to different
values of specimen thickness. In order to avoid complexity and non-uniqueness of the multi-parameter minimization for randomly
oriented polydisperse block-like precipitate model, the data have been analyzed assuming randomly oriented polydisperse cylindrical
particle model with a locked aspect ratio. 相似文献
970.
The norm kernel of the A=12 system composed of two 6He clusters, and the L=0 basis functions (in the SU(3) and angular momentum-coupled schemes) are analytically obtained in the Fock-Bargmann space. The norm kernel has a diagonal form in the former basis, but the asymptotic conditions are naturally defined in the latter one. The system is a good illustration for the method of projection of the norm kernel to the basis functions in the presence of SU(3) degeneracy that was proposed by the authors. The coupled-channel problem is considered in the algebraic version of the resonating-group method, with the multiple decay thresholds being properly accounted for. The structure of the ground state of 12Be obtained in the approximation of zero-range nuclear force is compared with the shell-model predictions. In the continuum part of the spectrum, the S-matrix is constructed, the asymptotic normalization coefficients are deduced and their energy dependence is analyzed. 相似文献