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171.
In this paper we deal with the ordered median problem: a family of location problems that allows us to deal with a large number
of real situations which does not fit into the standard models of location analysis. Moreover, this family includes as particular
instances many of the classical location models. Here, we analyze thep-facility version of this problem on networks and our goal is to study the structure of the set of candidate points to be
optimal solutions.
The research of the authors is partially financed by Spanish research grants BFM2001-2378, BFM2001-4028, BFM2004-0909 and
HA2003-0121. 相似文献
172.
This paper presents an elementary derivation for the nth moment of magnetic resonance linear response lineshape using sum rules for two time retarded Green's functions. The results can be particularized to the high-temperature regime where van Vleck's well-known relations are obtained. 相似文献
173.
174.
PHOTODYNAMIC EFFECTS INDUCED BY FUROCOUMARINS ON A MEMBRANE SYSTEM. COMPARISON WITH HEMATOPORPHYRIN 总被引:1,自引:0,他引:1
Abstract Isolated rat liver mitochondria have been used as a model to investigate the photodynamic action of psoralen (Ps) and 4,5',8-trimethylpsoralen (TMP) on cellular membrane systems in comparison with hematoporphyrin (Hp). Oxidation was detected by the consumption of free oxygen as measured polarographically in the respiratory chamber when irradiated with UV light (320-380 nm). In the presence of Ps, singlet oxygen was produced in the respiratory medium but neither the respiration nor the oxidative phosphorylation were affected. On the contrary the hydrophobic derivative TMP impaired the respiration with rapid uncoupling of oxidative phosphorylation as did Hp. The ineffectiveness of Ps as well as the effectiveness of TMP vs. Hp is explained on the basis of photophysical properties of the molecules and their partition coefficient. These results may indicate that, in the photochemiotherapy of skin diseases, furocoumarins can drive photodynamic reactions at various subcellular levels according to their hydrophobicity. 相似文献
175.
Oscar Moreno 《Discrete Mathematics》1982,41(1):53-56
The object of this paper is to present a simple proof for the existence of primitive elements of trace equal 1, in GF(2m). 相似文献
176.
Velocity and attenuation of sound wave propagation along the [100] direction in NH4Br were measured near its transition temperature Tc = 234.5 K at frequencies of 30–150 MHz. The experimental results for the high-frequency attenuation and the dispersive velocity shifts are found to be in good agreement with the model of a single critical relaxation time. 相似文献
177.
Correa A Tellitu I Domínguez E Moreno I Sanmartin R 《The Journal of organic chemistry》2005,70(6):2256-2264
[reaction: see text] The synthesis of a series of optically pure benzo-, naphtho-, and heterocycle-fused pyrrolo[2,1-c][1,4]-diazepin-5,11-dione derivatives starting from l-proline methyl ester is presented. The synthetic plan includes an aroylation step at the proline nitrogen followed by transformation of the ester residue into a N-methoxyamide group. The subsequent key cyclization step embraces the PIFA mediated formation of a N-acylnitrenium intermediate and its succeeding intramolecular trapping by the aromatic ring. The presented general approach solves the need of starting from not very accessible amino (or a related functionality) aromatic starting materials, and its effectiveness is demonstrated in the synthesis of the antitumor antibiotic DC-81. 相似文献
178.
Anionic groups (AGs) on different cellulosic fiber surfaces were investigated by methylene blue (MB) and polyelectrolyte (PE) sorption, X-ray photoelectron spectroscopy (XPS), and total attenuated reflectance infrared spectrometry (FTIR-ATR). The MB sorption isotherms fitted well the Langmuir equation that gave consistent estimations of sorption capacities. FTIR-ATR showed that MB molecules had extensive accessibility to the fiber wall pores. Estimation of surface AGs by PE sorption gave much higher values than a new method combining MB sorption and XPS measurements (MB-XPS). The surface AGs in different cellulosic fibers accounted for 1-3% of the total AG content as revealed by MB-XPS. It was suggested that PE molecules can penetrate the fiber wall and form loops or unattached segments at external fiber surfaces that disrupt the PE sorption stoichiometry. The competition of MB and PE for the anionic sites in papermaking was assessed and it was shown that MB ions have a much stronger affinity to AGs than PE molecules. 相似文献
179.
180.
C. Ceccarelli P. De Bernardis S. Masi F. Melchiorri G. Moreno L. Pietranera G. Dall'Oglio B. Melchiorri N. Mandolesi G. Morigi 《Il Nuovo Cimento C》1985,8(4):374-378
Summary We show how combined large-beam infra-red and radio observations toward the Virgo Cluster may be explained by assuming the
existence of a large tepid halo surrounding the giant galaxy M87. Such a halo would be able to close the cluster gravitationally.
If interpreted as being due to bremmstrahlung radiation by a tepid extended halo, it also explains the infra-red observations,
and it has important implications for the physics of M87.
Paper presented at the Congress ?Galactic and Extragalactic Dark Matter?, Roma, 28 to 30 June 1983. 相似文献