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951.
In this paper, the long-run dynamics of a resonant converter is studied. The modelling of the resonant converter can be done using various approximations and the long-run dynamics of the two dimensional cases were earlier analysed. In this paper, we discuss results that can be extended to the three dimensional case. It seems that limit cycles describe the long-run dynamics in important situations in the three dimensional case, too. Our objective is to relate the limit cycles found previously in the two-dimensional case to those found now in the three dimensional approximation. 相似文献
952.
953.
Recently Koulamas and Kyparisis [Koulamas, C., Kyparisis, G.J., in press. Single-machine scheduling with past-sequence-dependent setup times. European Journal of Operational Research] introduced past-sequence-dependent setup times to scheduling problems. This means that the setup time of a job is proportionate to the sum of processing times of the jobs already scheduled. Koulamas and Kyparisis [Koulamas, C., Kyparisis, G.J., in press. Single-machine scheduling with past-sequence-dependent setup times. European Journal of Operational Research] were able to show for a number of single-machine scheduling problems with completion time goals that they remain polynomially solvable. In this paper we extend the analysis to problems with due dates. We demonstrated that some problems remain polynomially solvable. However, for some other problems well-known polynomially solution approaches do not guarantee optimality any longer. Consequently we concentrated on finding polynomially solvable special cases. 相似文献
954.
Jan Nisar Mukhtiar Ali Iftikhar Ahmad Awan Amir Badshah Sadullah Mir Rafaqat Ali Khan 《Reaction Kinetics and Catalysis Letters》2009,98(2):375-381
The gas-phase thermal decomposition of cis-2-methylcyclopropane carboxylic acid was investigated in the temperature range
692–753 K and pressure between 10 and 70 Torr. Arrhenius parameters were determined for homogeneous, unimolecular formation
of the isomeric products and for the overall loss-rate of the reactant. The determined values are in accordance with the Arrhenius
parameters that were reported previously for the thermal unimolecular reactions of cyclopropane and other substituted cyclopropanes.
The formation of isomeric products and the observed Arrhenius parameters are consistent with a biradical mechanism. The effect
of surface on the reaction was studied at 732 K using the packed reaction vessel. It was observed that the rate of production
of all isomeric products and the total loss of cis-2-methylcyclopropane carboxylic acid were not affected by increasing surface
to volume ratio. 相似文献
955.
estmír ejka Jan Pláteník Richard Buchal Vilém Guryca Jakub irc Martin Vejraka Jiina Crkovská Taras Ardan Jií Michálek Blanka Brnová Jitka ejková 《Photochemistry and photobiology》2009,85(3):794-800
The aim of the present paper was to examine the irradiation effect of two doses of UVA rays (365 nm) on the rabbit cornea and lens. Corneas of anesthetized adult albino rabbits were irradiated with UVA rays for 5 days (daily dose 1.01 J cm−2 in one group of rabbits and daily dose 2.02 J cm−2 in the second group of animals). The third day after the last irradiation, the rabbits were killed, and their eyes were employed for spectrophotometrical, biochemical and immunohistochemical investigations. Normal eyes served as controls. Absorption spectra of the whole corneal centers were recorded over the UV–VIS (visible) spectral range. Levels of antioxidant and prooxidant enzymes, nitric oxide synthases and nitric oxide (indirectly measured as nitrate concentration) were investigated in the cornea. Malondialdehyde, a byproduct of lipid peroxidation, was examined in the cornea and lens. The results show that the staining for endothelial nitric oxide synthase was more pronounced in corneas irradiated with the higher UVA dose. Otherwise, UVA rays at either dose did not significantly change corneal light absorption properties and did not cause statistically significant metabolic changes in the cornea or lens. In conclusion, UVA rays at the employed doses did not evoke harmful effects in the cornea or lens. 相似文献
956.
957.
958.
During the last years both Erd?s space and complete Erd?s space were topologically characterized by Dijkstra and van Mill. Applications include results about Erd?s type spaces in ?p-spaces as well as results about Polishable ideals on ω. We present an unifying theorem in terms of sets with a reflexive relation that among other things contains these apparently dissimilar results as special cases. 相似文献
959.
Sergey Sergeyev Sara Stas Adrienne Remacle Christophe M.L. Vande Velde Bohumil Dolenský Martin Havlík Vladimír Král Jan Čejka 《Tetrahedron: Asymmetry》2009,20(16):1918-1923
The separation of enantiomers of several ‘bis- and tris-Tröger’s bases’ by HPLC on commercially available chiral stationary phase Whelk O1 is described for the first time. The observed structure–enantioselectivity relationships are in agreement with the previously established molecular recognition model. For all ‘bis- and tris-Tröger’s bases’ studied, satisfactory to excellent enantioselectivities were observed. 相似文献
960.
Summary The composition of the eluent system in some instances determines the resolution and elution order of solutes in the reversed-phase chromatographic separation on cyclodextrin stationary phases. Both the identity and the concentration of the organic modifier can play a large role. The effect is particularly pronounced with naphthalene and its methyl derivatives with alcohol eluents.
Elutionsfolge bei der Flüssig-Chromatographie auf Cyclodextrinphasen. Abhängigkeit vom Gehalt an organischem Modifier im Eluenten相似文献