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排序方式: 共有533条查询结果,搜索用时 15 毫秒
1.
H. Sato A. Bensalah N. Solovieva A. Beitlerova A. Vedda M. Martini M. Nikl T. Fukuda 《Radiation measurements》2004,38(4-6):463-466
Two-inch sized KMgF3,BaLiF3 and LiCaAlF6 (LiCAF) single crystals were grown by the Czochralski method under a CF4 atmosphere. X-ray irradiation was used to carry out a comparative study of induced optical absorption phenomena and colour centre creation in the ultra-violet and visible spectral regions. The integral of the induced absorption spectra is significantly lower in LiCAF with respect to the other studied materials. It is found that the amplitude of the F-absorption band is suppressed more than a factor of 3 by Mg-doping. For Mg-doped crystals, the optimum doping concentration is about 0.2 mol% of Mg2+. 相似文献
2.
Horst Martini 《Discrete and Computational Geometry》1991,6(1):83-91
In a paper by the author and B. Weissbach it was proved that the projection body and the difference set of ad-simplex (d≥2) are polars. Obviously, ford=2 a convex domain has this property if and only if its difference set is bounded by a so-called Radon curve. A natural question
emerges about further classes of convex bodies inR
d
(d≥3) inducing the mentioned polarity. The aim of this paper is to show that a convexd-polytope (d≥3) is a simplex if and only if its projection body and its difference set are polars. 相似文献
3.
We investigate multiphoton states generated by high-gain optical parametric amplification of a single injected photon—polarization encoded as a qubit. The experimental configuration exploits the optimal phase-covariant cloning. The output state of the apparatus is found to exhibit the quantum superposition property of mesoscopic multiphoton assemblies involving about 300 photons. This work represents an experimental advance toward the test of several fundamental quantum processes in mesoscopic or macroscopic frameworks. 相似文献
4.
Measurable supports,reducible spaces and the structure of the optimal σ-field in unbiased estimation
Immanuel M. Bomze 《Monatshefte für Mathematik》1986,101(1):27-38
This paper generalizes a result bySapozhnikov relating the structure of the optimal -field in unbiased estimation to the reducibility of certain linear subspaces of estimators. For this purpose, the concept of a measurable support of (uncountably infinite) sets consisting of random variables is introduced, which could be of general interest. It turns out, that for a wide class of measure spaces, measurable supports of any subsets of measurable functions exist. 相似文献
5.
Sandra Ristori Grard Gebel Giacomo Martini 《Colloids and surfaces. A, Physicochemical and engineering aspects》1993,80(2-3):113-120
The aggregation properties of ammonium perfluorooctanoate (NH4-PFO) in concentrated aqueous phases have been investigated by magnetic resonance techniques and have been compared with the aggregation properties in dilute solutions. Magnetic resonance methods indicated that NH4-PFO—water systems with surfactant concentrations below 45% (w/w) behaved as isotropic purely micellar solutions in the temperature range 285–340 K. For higher concentrations the system exhibited a rather complex structure, having both isotropic and anisotropic components. The nematic nature of the anisotropic fraction was demonstrated by 19F NMR studies. The 19F NMR and EPR of nitroxides (TempTMA+, 5- and 16-DXSA) inserted as paramagnetic probes into the concentrated NH4-PFO—water systems allowed us to establish that the lamellar phase could be mechanically oriented between quartz slides. The EPR investigation also gave details concerning the dynamics of both the oriented and non-oriented structures. 相似文献
6.
In this paper we consider a new class of convex bodies which was introduced in [11]. This is the class of belt bodies, and it is a natural generalization of the class of zonoids (see the surveys [18, 28, 24]). While the class of zonoids is not dense in the family of all centrally symmetric, convex bodies, the class of belt bodies is dense in the set of all convex bodies. Nevertheless, we shall extend solutions of combinatorial problems for zonoids (cf. [2, 12]) to the class of belt bodies. Therefore, we first introduce the set of belt bodies by using zonoids as starting point. (To make the paper self-contained, a few parts of the approach from [11] are given repeatedly.) Second, complete solutions of three well-known (and generally unsolved) problems from the combinatorial geometry of convex bodies are given for the class of belt bodies. The first of these, connected with the names of I. Gohberg and H. Hadwiger, is the problem of covering a convex body with smaller homothetic copies, or the equivalent illumination problem. The second is the Szökefalvi-Nagy problem, which asks for the determination of the convex bodies whose families of translates have a given Helly dimension. The third problem concerns special fixing systems, a notion which is due to L. Fejes Tóth. These solutions consist of improved and more general approaches to recently solved problems (as in the case of the Helly-dimensional classification of belt bodies) or new results (as those concerning minimal fixing systems, providing also an answer to a problem of B. Grünbaum which is not only restricted to belt bodies). 相似文献
7.
Armstrong TA Bettoni D Bharadwaj V Biino C Borreani G Broemmelsiek D Buzzo A Calabrese R Ceccucci A Cester R Church M Dalpiaz P Dalpiaz PF Dimitroyannis D Fabbri M Fast J Gianoli A Ginsburg CM Gollwitzer K Govi G Hahn A Hasan M Hsueh S Lewis R Luppi E Macrí M Majewska AM Mandelkern M Marchetto F Marinelli M Marques J Marsh W Martini M Masuzawa M Menichetti E Migliori A Mussa R Palestini S Pallavicini M Passaggio S Pastrone N Patrignani C Peoples J Petrucci F Pia MG Pordes S Rapidis P Ray R 《Physical review D: Particles and fields》1996,54(11):7067-7070
8.
L. Bardi C. Martini F. Opsi E. Bertolone S. Belviso G. Masoero M. Marzona F. Ajmone Marsan 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):439-444
In situ bioremediation of polycyclic aromatic hydrocarbons (PAH) polluted soils can be improved by the augmentation of degrading
microbial populations and by the increase of hydrocarbon bioavailability. β-cyclodextrin (β-CD) significantly accelerate the
induction of hydrocarbon biodegradation, but it is not still clear its effectiveness during final, slower stages of degradation.
Moreover, it is yet not known if the PAH uptake from plants is influenced by the presence of CD. A field study was carried
out by creating two plots (A and B). Diesel fuel was spread on the surface, and on plot B a commercial microbial consortium
and β-CD were spread. Soybean was seeded in both plots. Soil samples were withdrawn every 10 cm layers from 0 to 60 cm depth,
before fuel spreading, immediately after seeding and after soya harvesting. Chemical and microbial analyses were carried out
throughout the process to characterize the soil and to determine residual PAHs. Soybean seeds were analyzed for PAH content.
It was observed that β-CD induced a significant increase of PAH degradation rate. The microbial inoculum did not improve the
degradation; biodegradation activity was strong in superficial layers, and some PAH leaching was observed, that was reduced
by CD. The analysis of PAH in soyabeans revealed that an uptake of hydrocarbons occurred, and that it was more significant
in plot B. This suggests that the β-CD-enhanced bioremediation process can further be improved by phytoremediation, that could
also allow to simultaneously reach an additional profit from a non-food yield for biofuel production. 相似文献
9.
We present a multipass femtosecond amplifier pumped by a Nd-YAG laser where the gain medium is given by a variable length dye cell. This system allows amplification factors up to 5 · 106 and output pulse energies of 150 J, while restricting the contribution of amplified spontaneous emission to 0.5% of the total output energy, without using any saturable absorber stage. A detailed study of the output pulsewidth as a function of the duration of the input chirped pulse is also presented. 相似文献
10.