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991.
LI Li LU XiaoYu CAO ChongDe & DAI FuPing Department of Applied Physics Northwestern Polytechnical University Xi’an China 《科学通报(英文版)》2010,55(16):1674-1678
Solidification of Fe-7.5%Mo-16.5%Si ternary quasiperitectic alloy is investigated by using differential scanning calorimetry (DSC) and drop tube containerless processing techniques.The primary phase is identified as R (Fe5Mo3Si2) and the quasiperitectic phases are τ1 (Fe5MoSi4) and Fe3Si.With the decrease of droplet diameter, the cooling rate and undercooling of the droplets in-crease rapidly.The experiment result indicates that the solidification microstructure is composed of remnant primary phase, qua-sip... 相似文献
992.
<正> This paper discusses the null boundary controllability of two PDE's,modeling a compositesolid with different physical properties in each layer.Interface conditions are imposed. 相似文献
993.
Compared with traditional structure-based approaches for the identification of species-specific ligands, the ab initio approach, based on large-scale protein sequences from different species, has been used to locate specific sites that may be important to the molecular selectivity of species. Statistically significant differences in the distribution of residues in different species and differences in the physicochemical properties of residue-specific sites may largely account for species selectivity. The nicotinic acetylcholine receptor (nAChR), an important neuro-receptor with significantly different ligand selectivity in different species, was used to test our method. Because of the lack of nAChR structural information, the mechanism of ligand discrimination is unclear which hinders attempts at novel molecular design. In this study, the specific site residues 186 and 189 in the principal subunits and residues 34, 55, 56, 57, 106 and 112 in complementary subunits of nAChR were identified by applying our method with stringent statistical cutoffs. These sites were predicted to contribute to ligand selectivity and this result coincides well with the known experimental data. 相似文献
994.
本文根据有关资料,比较和分析了美国、日本、韩国、泰国及印度等国同我国在农业生产率方向的相关差异. 相似文献
995.
发现了航片水平、地形平坦的理想状态下,关于立体象对象基线的一个恒等式:b=r1|cosa|+r2|cosβ|,式中b为立体象对的象基线,r1、r2为航片上任意一个同名象点在立体象对左右邻片上的辐射距,α,β为该同名象点左右邻片上的辐射距与立体象对象基线的夹角。 相似文献
996.
本文通过对风险厌恶模型解的性态分析 ,揭示了风险厌恶度的经济意义 ,并由此给出了确定最佳证券组合一种新方法———几何法 ,该方法较传统的无差异曲线法简单直观 ,便于操作 相似文献
997.
998.
Different from traditional tax audit, supervision with self-audit is a combination of audit by the taxpayer himself and audit by the tax authority. This paper mainly studies a taxpayer's optimal policy of tax evasion under supervision with self-audit and its related properties, in order to deduce some effective suggestions and theoretical bases to restrain tax evasion. Assuming that only a certain proportion of evaded tax can be discovered when the audit is executed, the authors first formulate a static model with self-audit. This model is divided into two stages. At the first stage, taxpayers declare their taxes, then the tax authority chooses audit objects, based on a known probability, and announces the result; if the taxpayer is chosen, he will enter the second stage, during which he has a chance to pay the evaded tax and the corresponding late fees and then is audited by the tax authority. The authors show the existence and uniqueness of the optimal amount of tax evasion at the first stage and the optimal proportion to self-expose at the second stage. The authors also discuss the related properties of the interior solution, and do elasticity analyses on some parameters. Besides, the authors extend the static model into the corresponding two-period model, and study the existence and uniqueness of the solution of the extended model. Finally, under the assumption that tax evasion can only be discovered with a certain probability when the audit is executed, the authors formulate another static model with self-audit and investigate its properties. 相似文献
999.
Ka频段鳍线平衡混频器的设计 总被引:1,自引:0,他引:1
鳍线是一种用于毫米波集成电路的新型准平面传输线,本文介绍了三种鳍线平衡混频器的设计与性能,混频器均使用价格便宜的梁式引线二极管和国产介质基片。第一种鳍线魔T混频器在窄带内性能较好,包括中放在内的DSB噪声系数最小值为4.9dB。第二种鳍线混频器在多个频率点有较好性能,包括中放在内的DSB噪声系数最小值为5.3dB。第三种鳍线混频器在给定频带内具有宽带特性,包括中放在内的DSB噪声系数最小值为5.6dB。 相似文献
1000.
薛银川 《宁夏大学学报(自然科学版)》1997,18(2):146-150
构造了三角形区域上一种新的二元Stancu型算子,讨论其在C空间的逼近性质和迭代的极限。 相似文献