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941.
根据发光层中电子能量分布的不均匀性,在分层优化薄膜电致发光器件的发光层中插入SiO2层,即级联分层优化薄膜电致发光器件。结果表明:由于SiO2的加速作用,这种方法确实可以提高过热电子的能量。但发光强度及发光效率的提高还受发光层的结晶状态的影响。插入一层SiO2后,样品的绿光强度提高了60%,发光效率也有所增加。插入两层SiO2后,由于发光层结晶状态变差,绿光强度及发光效率都降低了。 相似文献
942.
Jean Schoentgen 《商业与工业应用随机模型》1988,4(2):127-135
The data we deal with are acoustic feature values computed from speech signals produced by normal control speakers and speakers suffering from a laryngeal pathology. The problem is (i) to compare the discriminatory performance of a given acoustic feature with other features of the same family; (ii) to compare the performance of corresponding features in studies carried out on corpora which were not identical and which did not contain the same number of speakers; (iii) to express quantitatively the share of laryngeal pathologies which could be detected reliably by acoustic means alone. We propose to accomplish tasks (i) to (iii) by separating pooled control and risk groups on the basis of the acoustic feature values alone and by evaluating the quality of approximation of the original groups so realized. In order to evaluate this quality we compute a merit factor satisfying the following properties: (1) to be independent of the number of speakers contained in the pooled control and risk groups; (2) to increase and decrease linearly with the detection and false alarm rates, respectively; (3) to take on values between 0 (no discrimination at all) and 1 (perfect discrimination). We also address the question of the confidence one may have in the merit factor values so achieved, i.e. we describe a method of computing the probability that a merit factor value might have been realized by chance alone. 相似文献
943.
Using a coculture system, we have studied the local action of Sertoli cells on Leydig cell function. The results show that (ⅰ) both LH and FSH have equal potency to stimulate testosterone biosynthesis by fetal and neonatal testicular cells in an age-dependent manner, the maximum stimulation is observed between D_3 and D_5. (ⅱ) An FSH-dependent factor(s) secreted by Sertoli cells increases the basal and/or LH-stimulated Leydig cell androgen production. (ⅲ) The Sertoli cell-stimulating factor(s) is not a steroid or other small molecule, but a heat-labile peptide. 相似文献
944.
Questions of asymptotic inference are discussed for a point process model in which the conditional intensity function increases monotonically between events and drops by determined (nonrandom) amounts after each event. Parameter estimates are shown to be consistent and, except under the null hypothesis of a Poisson process, normally distributed. Under the null hypothesis, however, the Hessian matrix is not asymptotically constant, and the limiting distribution of the likelihood ratio statistics is not χ2, but has a form related to that of the Cramer-von Mises ω2 statistic for the test of goodness of fit. 相似文献
945.
S Srinivasa Raghavan 《Pramana》1979,13(2):159-162
The suitability of a soft-core radial wave function in4He calculations is tested by computing the charge form factor of the alpha particle. The free parameter in the radial function
is fixed in a photo-disintegration calculation. The results show that the soft-core function is suitable and the ground state
of4He may be described reasonably well if a suitable potential model is used with it. 相似文献
946.
This work reports on the effects of structural inhomogeneities within the models of spherical atomic packings on the radial distribution function (RDF) and the structural factor (SF). Models of inhomogeneous packings were constructed by removing some atoms from homogeneous packing according to a predetermined template. Thus various additional voids, leading to specific structural correlations of atoms on a middle scale (several atomic sizes), are introduced in the model. A dense noncrystalline packing of 27,000 Lennard-Jones atoms serves as the initial system. Three various templates were used, and models containing different fractions of additional voids were constructed with each of these templates. It is demonstrated that RDF is only slightly sensitive to such inhomogeneities; in contrast, the SF has additional peaks at small q, these peaks being notable even after removal of a small fraction of atoms. Some models yield a single narrow prepeak, which is akin to that observed in diffraction experiment for some glasses. 相似文献
947.
Uniform estimate for maximum of randomly weighted sums with applications to insurance risk theory 总被引:1,自引:0,他引:1
WANG Dingcheng~ SU Chun~ & ZENG Yong~ . School of Management School of Applied Mathematics University of Electronic Science Technology of China Chengdu China . Department of Statistics Finance University of Science Technology of China Hefei China 《中国科学A辑(英文版)》2005,48(10):1379-1394
This paper obtains the uniform estimate for maximum of sums of independent and heavy-tailed random variables with nonnegative random weights,which can be arbi- trarily dependent of each other.Then the applications to ruin probabilities in a discrete time risk model with dependent stochastic returns are considered. 相似文献
948.
In this paper, we show that if type von Neumann factors have some decompositions introduced by Liming Ge and Sorin Popa, then these von Neumann factors are not isomorphic to free group factors . Thus we have proved the number defined by Ge and Popa bigger than 3 for all free group factors and we also extend some results of M. Stefan.
949.
S V Deshmukh 《Pramana》1978,11(6):755-760
The effect of Gaunt factor correction on temperature estimation over a range 100 to 1500 eV had been studied. Greene’s analytical
expression for the quantum mechanical Gaunt factor averaged over Maxwellian distribution is used. Transmission ratios are
calculated with and without Gaunt factor for various combinations of beryllium foils, taking into account x-ray emission due
to free-free transitions. A significant difference (≳ 15%) is observed between the temperatures estimated from classical and
quantum mechanical curves, above 600 eV. Selection of foil combinations useful for estimating higher temperatures is also
discussed. 相似文献
950.
The emission of radiation from relativistic positrons moving in the 〈110〉 axial channels of an f.c.c. (diamond) crystal has
been studied. An expression for the radiation intensity has been obtained for the general case of positron motion. This expression
has been simplified for the particular case of well-collimated incident beam. Enhancement of the radiation over (ordinary)
bremsstrahlung has been discussed. 相似文献