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991.
Xiang-Yu Wang Xiao-Jun Bi Zhen Cao Piero Vallania Han-Rong Wu Da-Hai Yan Qiang Yuan 《中国物理C(英文版)》2022,(3):63-84
Extra-galactic gamma-ray sources,such as gamma-ray bursts,active galactic nuclei,starburst galaxies,are interesting and important targets for LHAASO observation... 相似文献
992.
993.
2‐Formylchromones and 3‐formylchromones as the first materials singly reacted with 2‐amino‐5‐mercapto‐1,3,4‐thiadiazole to give the corresponding Schiff bases, which on cyclocondensation with mercapto‐acetic acid in 1,4‐dioxane yielded target compounds named 4‐oxo‐thiazolidines. The structures of all the synthetic compounds were confirmed by elemental analysis and IR, 1H NMR, LC‐MS (ESI) spectral data. 相似文献
994.
P.A. Hu Y.Q. Liu L. Fu L.C. Cao D.B. Zhu 《Applied Physics A: Materials Science & Processing》2005,80(7):1413-1417
Inorganic fullerene-like (IF) nanotubes constructed from layered metal chalcogenides are of particular significance because of their excellent physical properties and potential application in wide fields. But very few previous studies were focused on the IF nanotubes of layered III-VI semiconductor. Therefore we investigate the preparation, structure and photoluminescence (PL) properties of GaS nanotube (an important III-VI semiconductor IF nanotube). A simple method is introduced to prepare GaS multi-walled nanotubes for the first time by annealing the natural lamellar precursor in Ar. The reaction temperature is crucial for the formation of nanotube. A suitable temperature range is 500–850 °C. Bulk quantities of GaS nanotubes with diameters of 30–150 nm and lengths up to ten micrometers were produced. Some of these nanotubes show corrugated and interlinked structure and form many segments, demonstrating a bamboo-like structure. As compared to bulk materials, the obvious distinction of the products in PL spectra at liquid nitrogen temperature of 77 K was due to the structure variety. PACS 61.46.+w; 81.07.De; 81.16.Be 相似文献
995.
Feilong Cao 《Journal of Approximation Theory》2005,132(2):241-257
We characterize the directional derivatives of multidimensional Bernstein operators by a new measure of smoothness. This task is carried out by means of establishing the relation between the asymptotic behavior of the derivatives and the smoothness of the functions they approximate. The obtained results generalize the corresponding ones for univariate Bernstein operators. 相似文献
996.
When the activation function possesses multilevel property, the Hopfield neural network has some novel dynamical behaviors, and it is worthwhile to study. First, some properties about the activation function are obtained, on this foundation, some theoretical analysis about the quasi-equilibrium points has been made. From local and global view, some theorems about the boundedness are presented. Finally, two theorems about the first derivative of trajectory with respect to time are found, the first theorem indicates that the trajectory cannot keep increasing or decreasing for time t > t0, the second theorem is about the complete stability of the trajectory. 相似文献
997.
运用电光采样技术揭示了反应离子刻蚀(RIE)ZnTe晶体表面THz辐射的光学整流产生机制, 观察到0.25 ps的THz场分布.通过比较刻蚀前后以及不同刻蚀条件下ZnTe样品在不同激发功 率下的THz辐射强度,发现由于反应离子刻蚀破坏了ZnTe样品表面的有序性,晶体的电光系 数随射频功率的增加而减小.借助于计算不同刻蚀条件下ZnTe晶体的频率响应函数,分析了 随射频功率增加ZnTe晶体响应频谱展宽的现象.
关键词:
THz辐射
反应离子刻蚀
ZnTe 相似文献
998.
分子拓扑学方法估算多环芳香烃类化合物的电离能 总被引:2,自引:0,他引:2
在构建多环芳烃类化合物分子的邻接矩阵主对角元时,结合烷基极化效应指数考虑分子图顶点的性质,以分子碎片C、CH、CH2、CH3等的相对能量作主元,用分子拓扑学方法构建了多环芳香烃类化合物新的邻接矩阵.研究结果发现,新的邻接矩阵特征根与多环芳香烃类化合物的电离能有良好的相关性Ipi=4.756+2.870OMOi,R=0.9853,s=0.1765,n=446.用这种新方法估算多环芳香烃类化合物的电离能,所用参数少且为分子结构性参数,稳定可靠,计算简便,结果较满意. 相似文献
999.
数值积分求解均匀带电圆环平面上的电场分布 总被引:5,自引:0,他引:5
本文用数值积分的方法计算椭圆积分,求出在均匀带电圆环平面上的场强与电势. 相似文献
1000.
Effect of Cu doping on the magnetic and electrical properties of n=2 Ruddlesden-Popper manganates 下载免费PDF全文
A series of polycrystalline Cu-doped n=2 Ruddlesden-Popper manganates La1.2Sr1.8CuzMn(2-x)O7 (x=0, 0.04, 0.13) were synthesized by the solid state reaction method. The effect of Cu doping on the magnetic and transport properties has been studied. It is found that Cu substitution for Mn greatly affects the magnetic and electrical properties of the parent phase La1.2Sr1.8Mn2O7. With the increase of Cu content, the system undergoes a transition from longrange ferromagnetic order to the spin glass state and further to an antiferromagnetic order. A little of Cu dopant can lead to the samples showing semiconductor or insulator behaviour in the whole observed temperature range while the parent phase has a metal-insulator transition. These samples show colossal magnetoresistance at low temperatures and the value of it decreases with increasing Cu content. 相似文献