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81.
A sample of 1233 events is used to study the general characteristics of {}^{16}O-Em interactions at 4.5 A GeV/c. Multiplicity and angular distributions of slow particles and correlations among them are discussed. The present data are compared with the corresponding results from the interactions of other projectiles at the same energy and also the same projectile at different energies. The results indicate that black particle production is independent of the energy and mass of the projectile, but for grey particles it is dependent on the mass of projectile. 相似文献
82.
We extend the matrix version of Cochran's statistical theorem to outer inverses of a matrix. As applications, we investigate the Wishartness and independence of matrix quadratic forms for Kronecker product covariance structures. 相似文献
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86.
A Promising MoO_x-based Catalyst for n-Heptane Isomerization 总被引:1,自引:0,他引:1
Song Hai CHAI Xin Ping WANG* Ying Jun WANG Tian Xi CAI State Key Laboratory of Fine Chemicals Dalian University of Technology Dalian 《中国化学快报》2003,14(7)
The increasing demand for higher-octane gasoline and the regulations limiting the amount of aromatics in the fuel motivate the interest in catalytic isomerization of n-alkanes. In the last ten years, transition metal oxides or oxycarbides based on molybdenum or tungstate have attracted much attention due to their high activity and isomerization selectivity compared to the conventional bifunctional supported platinum catalyst and high resistance to sulphur and nitrogen catalyst poisons1-5. Ma… 相似文献
87.
We investigate the origin of ultraviolet (UV) emission from Mg0.12 Zn0.88 O alloy thin films with a wurtzite structure fabricated on c-plane Al2O3 substrates by plasma assisted molecular beam epitaxy. At room temperature, the absorption edge and UV emission band of the Mg0.12Zn0.88O film shift to high-energy side compared with ZnO films. Temperature dependence of the photoluminescence spectra shows that the UV emission is composed of free exciton and neutral donor bound exciton emissions. Two-step dissociation processes of the UV emission are observed with the increasing temperature. The thermal quenching mechanism is attributed to the dissociation of the free exciton from the neutral donor bound exciton in the low temperature region and the dissociation of free electron and hole from the free exciton in the high temperature region. 相似文献
88.
A new electroactive polynuclear inorganic compound of rare earth metal, gadolinium hexacyanoferrate (GdHCF), was prepared and characterized using the techniques of FTIR spectroscopy, thermogravimetric analysis (TG), UV-Vis spectrometry, X-ray photoelectron spectroscopy (XPS), ICP atomic emission spectroscopy, and EDX. The results of ICP atomic emission spectroscopy, EDX, and TGA indicated that the prepared GdHCF sample had a stoichiometry of NaGdFe(CN)6·12H2O (when GdHCF was prepared in NaCl solution). The FTIR spectrum of GdHCF showed that there were two types of water molecules in the structure of GdHCF: one was the interstitial water (5 H2O), which resulted from the association of water due to H-bonding, and the other was water coordinated with Gd (7 H2O). The results obtained using XPS showed that the oxidation state of Fe and Gd in the GdHCF sample was +2 and +3, respectively. GdHCF was immobilized on the surface of spectroscopically pure graphite (SG) electrode forming the GdHCF/SG electrode, and the solid-state electrochemistry of the resultant electrode was studied using cyclic voltammetry. The cyclic voltammetric results indicated that the GdHCF/SG electrode exhibited a pair of well-defined and stable redox peaks with the formal potential of E0′=(197±3) mV. The effects of the concentration of the supporting electrolyte on the electrochemical characteristics of GdHCF were studied, and the results showed that the value of E0′ increased linearly with the activity of the cationic ion of the supporting electrolyte (lgaNa+), with a slope of 54.1 mV, which may become a novel method for determining the activity of Na+ in solution. Further experimental results indicated that GdHCF had electrocatalytic activities toward the oxidation of dopamine (DA) and ascorbic acid (AA), and the electrocatalytic current increased linearly with the concentration of DA (or AA) in the range of 1.0–10.0 mmol·L?1 (for DA) or 0.5–20.0 mmol·L?1 (for AA). 相似文献
89.
Oriented 2-factorable graphs are reduced to bouquets by permutation voltage assignment in this paper. Introducing the concept ofk-class index of a permutation group, various oriented 2-factorable graphs are enumerated in this paper. 相似文献
90.