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101.
Maurizio Zandomeneghi Marino Cavazza Luigi Moi Francesco Pietra 《Tetrahedron letters》1980,21(2):213-214
Kr-ion laser irradiation of carvone () at 350.7 and 356.4 nm gave carvonecamphor () in a much higher yield (88%) than in conventional photochemistry, while () was a primary photo-by-product. 相似文献
102.
Dynamic photoelastic and moiré techniques were used to study the incident, reflected and refracted waves in a layered model. The model, consisting of two birefringent layers with an impedance ratio of approximately 2∶1, was subjected to point-source explosive loading in the low-impedance medium. The isochromatic and moiré-fringe patterns were photographed with a Cranz-Schardin multiplespark camera operating at a rate of 200,000 frames per second. Propagation and attenuation characteristics of waves in both layers were studied. The formation of head-waves at the interface was clearly evident. Stress determinations were made in some instances using photoelastic and moiré data. 相似文献
103.
Ermilas Alcalde Javier De Mendoza Jos Elguero Juan Marino Garcia-Marquina Consuelo Almera 《Journal of heterocyclic chemistry》1974,11(3):423-429
The three compounds C8 H10N4 which arise from reaction of hydrazine and β-aminocrotonitrile have been identified: the formation of anazine, a 3(5)-amino 5(3)-methyl pyrazole derivative and a 7-amino pyrazolo [1,5-a] pyrimidine has been demonstrated. The relationships among these compounds and with the methyl-aminopyrazole have been studied. 相似文献
104.
Antonio Cicone Nicola Guglielmi Stefano Serra-Capizzano Marino Zennaro 《Linear algebra and its applications》2010,432(2-3):796-816
This paper deals with the joint spectral radius of a finite set of matrices. We say that a set of matrices has the finiteness property if the maximal rate of growth, in the multiplicative semigroup it generates, is given by the powers of a finite product.Here we address the problem of establishing the finiteness property of pairs of sign-matrices. Such problem is related to the conjecture that pairs of sign-matrices fulfil the finiteness property for any dimension. This would imply, by a recent result by Blondel and Jungers, that finite sets of rational matrices fulfil the finiteness property, which would be very important in terms of the computation of the joint spectral radius. The technique used in this paper could suggest an extension of the analysis to sign-matrices, which still remains an open problem.As a main tool of our proof we make use of a procedure to find a so-called real extremal polytope norm for the set. In particular, we present an algorithm which, under some suitable assumptions, is able to check if a certain product in the multiplicative semigroup is spectrum maximizing.For pairs of sign-matrices we develop the computations exactly and hence are able to prove analytically the finiteness property. On the other hand, the algorithm can be used in a floating point arithmetic and provide a general tool for approximating the joint spectral radius of a set of matrices. 相似文献
105.
In [G. Lunardon, Semifields and linear sets of PG(1,qt), Quad. Mat., Dept. Math., Seconda Univ. Napoli, Caserta (in press)], G. Lunardon has exhibited a construction method yielding a theoretical family of semifields of order q2n,n>1 and n odd, with left nucleus Fqn, middle and right nuclei both Fq2 and center Fq. When n=3 this method gives an alternative construction of a family of semifields described in [N.L. Johnson, G. Marino, O. Polverino, R. Trombetti, On a generalization of cyclic semifields, J. Algebraic Combin. 26 (2009), 1-34], which generalizes the family of cyclic semifields obtained by Jha and Johnson in [V. Jha, N.L. Johnson, Translation planes of large dimension admitting non-solvable groups, J. Geom. 45 (1992), 87-104]. For n>3, no example of a semifield belonging to this family is known.In this paper we first prove that, when n>3, any semifield belonging to the family introduced in the second work cited above is not isotopic to any semifield of the family constructed in the former. Then we construct, with the aid of a computer, a semifield of order 210 belonging to the family introduced by Lunardon, which turns out to be non-isotopic to any other known semifield. 相似文献
106.
107.
In this Letter, we present the first systematic report of shear-induced banding in microconfined biphasic liquid-liquid systems, i.e., formation of alternating regions of high and low volume fraction of dispersed-phase droplets in a parallel plate flow cell. Such a flow-driven, gap-dependent phenomenon is only observed at low values of the viscosity ratio between the dispersed and the continuous phase, and in a given range of the applied shear rate. Based on rheological measurements, band formation is found to be associated with a viscosity decrease as compared to the homogeneous, structureless case, thus showing that system microstructure is somehow evolving towards reduced viscous dissipation under shear flow. 相似文献
108.
We have observed a violation of the Cauchy-Schwarz inequality in the macroscopic regime by more than 8 standard deviations. The violation has been obtained while filtering out only the low-frequency noise of the quantum-correlated beams that results from the technical noise of the laser used to generate them. We use bright intensity-difference squeezed beams produced by four-wave mixing as the source of the correlated fields. We also demonstrate that squeezing does not necessarily imply a violation of the Cauchy-Schwarz inequality. 相似文献
109.
Giuliano Bandoli Alessandro Dolmella Stefano Gatto Marino Nicolini 《Journal of chemical crystallography》1994,24(5):301-310
The solid-state structures of four 1,2,3,4-tetrahydroacridines [tacrine hydrochloride monohydrate (1), 7-methoxytacrine hydrochloride monohydrate (2), velnacrine hydrogenmaleate (3) and suronacrine hydrogenmaleate (4)] were determined from single-crystal X-ray diffraction analysis. (1): monoclinic,P21/n, a=8.778(1),b=8.521(1),c=17.603(2)Å, =101.34(1)°. (2): monoclinic,C2/c, a=12.326(7),b=18.050(9),c=13.822(8)Å, =113.70(4)°. (3): triclinic,
,a=7.349(2),b=9.417(3),c=12.557(4)Å, =109.62(2), =98.12(2), =101.18(2)°. (4): monoclinic,P21/n, a=8.513(6),b=18.74(1),c=13.401(6)Å, =91.21(5)°. FinalR factors for compounds(1)–(4) are 0.047, 0.057, 0.057, 0.11, respectively. The overall arrangement of the common aminotetrahydroacridine skeleton looks similar in all derivatives. However, whereas enantiomerization of the unsubstituted cyclohexenyl rings occurs in (1) and (2), onlyquasi-axially hydroxyl substituted diastereomers are found for (3) and (4). This is presumably due to the different propensities for hydrogen bonding of axially vs. equatorially disposed hydroxyl groups with the hydrogenmaleate anions. Empirical and semiempirical calculations were performed to examine the conformational behavior of the four compounds, bothin vacuo and in solution. 相似文献
110.