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961.
P Nürnberg I Barth E Fuhrmann C Lenzner T Losanova C Peters H P?che G Thiel 《Electrophoresis》1991,12(2-3):186-192
Germline and somatic instability of the human genome was studied, using synthetic oligonucleotides specific for simple repeat motifs. The following probes were used: (GTG)5, (GACA)4, (GATA)4, (CT)8, (TTAGGG)3, (GT)8, (GAA)6 and (GGAT)4. Each of them is unique with respect to the target regions recognized in the genome. Thus compilation of the various fingerprint data provides a complex map of the genome (and its deviations). While the fingerprints of differentiated somatic tissues never showed any alterations, in tumor tissues (namely gliomas) many changes could be detected. Most of the latter reflect secondary karyological aberrations. In nearly one third of the gliomas, drastically amplified and apparently monomorphic DNA fragments were identified. This marker should make it possible to deal with causal pathogenetic mechanisms as well as novel diagnostic strategies. 相似文献
962.
Qingxue Huang 《Journal of Graph Theory》1991,15(1):1-6
Graham and Pollak [3] proved that n ?1 is the minimum number of edge-disjoint complete bipartite subgraphs into which the edges of Kn can be decomposed. Using a linear algebraic technique, Tverberg [2] gives a different proof of that result. We apply his technique to show that for “almost all n,” ? (n + m ?3)/(m ?1) ? is the minimum number of edge-disjoint complete m-partite subgraphs in a decomposition of Kn. 相似文献
963.
P. Y. Zhu 《Il Nuovo Cimento C》1991,14(3):263-283
Summary The effective-medium approximation is applied to investigate scattering from a half-space of randomly and densely distributed
discrete scatterers. Starting from vector wave equations, an approximation, called effective-medium Born approximation, a
particular way, treating Green's functions, and special coordinates, of which the origin is set at the field point, are used
to calculate the bistatic- and back-scatterings. An analytic solution of backscattering with closed form is obtained and it
shows a depolarization effect. The theoretical results are in good agreement with the experimental measurements in the cases
of snow, multi- and first-year sea-ice. The root product ratio of polarization to depolarization in backscattering is equal
to 8; this result constitutes a law about polarized scattering phenomena in the nature. 相似文献
964.
J. H. de Araújo J. B. M. da Cunha A. Vasquez L. Amaral J. T. Moro F. C. Montenegro S. M. Rezende M. D. Coutinho Filho 《Hyperfine Interactions》1991,67(1-4):507-511
57Fe Mössbauer effect measurements in the diluted Ising antiferromagnet Fe x Zn1?x F2 withx=0.25 andx=0.57 at temperatures between 4.2 and 55 K, are reported. DC suceptibility measurements show a spin-glass (SG) phase at low temperatures forx≤0.31. Our Mössbauer spectra show a phase transition to a SG state with antiferromagnetic order (AFSG) forx=0.25 and only antiferromagnetic order forx=0.57. 相似文献
965.
966.
967.
In this paper, we consider a real-life vehicle routeing problem that occurs in a major Swiss company producing pet food and flour. In contrast with usual hypothetical problems, a large variety of restrictions has to be considered. The main constraints are relative to the accessibility and the time windows at customers, the carrying capacities of vehicles, the total duration of routes and the drivers' breaks. To find good solutions to this problem, we propose two heuristic methods: a fast straightforward insertion procedure and a method based on tabu search techniques. Next, the produced solutions are compared with the routes actually covered by the company. Our outcomes indicate that the total distance travelled can be reduced significantly when such methods are used. 相似文献
968.
969.
A simpler model for concentrated vortices 总被引:7,自引:0,他引:7
970.
Using the appropriate harmonic oscillator states and reasonable approximations, we construct coherent wavepackets corresponding
to the solutions of the Klein-Gordon equation for the attractive potentialV(r)=−k/r, k>0, in two and three space dimensions. We deduce the corresponding classical limit in two dimension by requiring that the
expectation value 〈r〉 of the radial variable is large. In the case of three dimensions, besides the condition of large 〈r〉, we make the uncertainty Δr=[〈r
2〉 − 〈r〉2]1/2 a minimum with respect to certain parameter of the wavepacket. We then investigate the trajectory traversed by the wavepacket
in the classical limit. We find that the classical limit of this relativistic quantal problem gives, in the leading order,
the same expression for the rate of motion of the perihelion as that given by the solution of the corresponding special relativistic
classical dynamical problem. We also briefly discuss some of the subtle aspects of the classical limit of the relativistic
quantal system, in general. 相似文献