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61.
62.
The magnetic hyperfine splitting (h.f.s.) in the 1s state of 7Li has been measured with a precision of 1% using the bent-crystal spectrometer facility at the SIN muon channel. With an instrumental resolution of 2.5 eV FWHM the h.f.s. was completely resolved in the 2p-1s transition. The result is ΔE(M1) = 4684 ± 49meV. A comparison of this result with the electromagnetic value yields a new upper limit for the strength of a possible muon-nucleon interaction mediated by an axial-vector boson, which is much lower than those that can be derived from other present data.  相似文献   
63.
A versatile online computer-based system for Kalousek polarography features simultaneous recording of oxidation and reduction currents, averaging over successive scans, and processing of the polarographic data by curve-fitting. The accuracy for determinations of cadmium, potassium and lithium down to 10-5 M is ± 5% for pulse rates up to 25 Hz.  相似文献   
64.
Let f(k) be the least positive integer n such that the complete graph with n vertices has a decomposition into k factors of diameter two. It is well known that f(2) = 5, f(3) = 12 or 13, and 4k ?1 ? f(k) ? 7k for every integer k ? 4. In the present paper it is proved that 6k ? 52 ? f(k) ? 6k for every integer k ? 2. (For k ? 370 also a better lower estimate of f(k) is given.)  相似文献   
65.
66.
This tutorial review surveys the use of thioglycosides in the development of sequential glycosylation methodologies, with a focus on chemoselective, orthogonal and iterative glycosylation strategies reported since the beginning of this century. Both fundamental aspects of glycosidic bond formation and ingenious state-of-the-art methodologies are presented.  相似文献   
67.
68.
Reaction of dicyclopentadienyltin(II) with pentamethylantimony gives [Me4Sb]2+[(C5H5)4Sn]2?, the first example of an anionic organotin(II) species.  相似文献   
69.
On the Lebesgue constant for the Xu interpolation formula   总被引:3,自引:0,他引:3  
In the paper [Y. Xu, Lagrange interpolation on Chebyshev points of two variables, J. Approx. Theory 87 (1996) 220–238], the author introduced a set of Chebyshev-like points for polynomial interpolation (by a certain subspace of polynomials) in the square [-1,1]2, and derived a compact form of the corresponding Lagrange interpolation formula. In [L. Bos, M. Caliari, S. De Marchi, M. Vianello, A numerical study of the Xu polynomial interpolation formula in two variables, Computing 76(3–4) (2005) 311–324], we gave an efficient implementation of the Xu interpolation formula and we studied numerically its Lebesgue constant, giving evidence that it grows like , n being the degree. The aim of the present paper is to provide an analytic proof to show that the Lebesgue constant does have this order of growth.  相似文献   
70.
The morphology and phase composition of porous silicon with galvanically deposited Fe and Co particles were investigated by ultrasoft X-ray emission spectroscopy, X-ray absorption near-edge structure spectroscopy, and scanning electron microscopy. It is shown that iron uniformly covers the surface of porous silicon, whereas cobalt penetrates into pores in the form of nanoparticles. It is established that iron is present mainly in the Fe2O3 phase with an admixture of FeO and Fe3O4. Cobalt forms a mixture of phases of metallic Co and Co2O3.  相似文献   
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