静压下ZnS：Te中Te等电子陷阱的发光

研究了4块ZnS：Te薄膜样品(Te组分从0．5％到3．1％)的光致发光谱在常压下的温度特性．对于Te组分较小的2块样品观察到2个发光峰，分别来自Te1和Te2等电子陷阱；而对Te组分较大的2块样品则只观察到1个来自Te2等电子陷阱的发光．我们还研究了这些发光峰在低温1．5K下的流体静压压力行为．观察到与Te1有关的发光峰压力系数比ZnS带边的要大很多，而与Te2有关的发光峰压力系数则比带边小．根据Koster-Slater模型，价带态密度半宽随压力的增加是Te1中心有较大压力系数的主要原因，而Te1和Te2中心的不同压力行为则是由于压力对两者缺陷势增强的不同效果引起的．     

Hierarchical structures in a turbulent pipe flow

A hierarchical structure (HS) analysis (β-test and γ-test) is applied to a fully developed turbulent pipe flow. Velocity signals are measured at two cross sections in the pipe and at a series of radial locations from the pipe wall. Particular attention is paid to the variation of turbulent statistics at wall units 10<y⁺<3000. It is shown that at all locations the velocity fluctuations satisfy the She–Leveque hierarchical symmetry (Phys. Rev. Lett. 72 (1994) 336). The measured HS parameters, β and γ, are interpreted in terms of the variation of fluid structures. Intense anisotropic fluid structures generated near the wall appear to be more singular than the most intermittent structures in isotropic turbulence and appear to be more outstanding compared to the background fluctuations; this yields a more intermittent velocity signal with smaller γ and β. As turbulence migrates into the logarithmic region, small-scale motions are generated by an energy cascade and large-scale organized structures emerge which are also less singular than the most intermittent structures of isotropic turbulence. At the center, turbulence is nearly isotropic, and β and γ are close to the 1994 She–Leveque predictions. A transition is observed from the logarithmic region to the center in which γ drops and the large-scale organized structures break down. We speculate that it is due to the growing eddy viscosity effects of widely spread turbulent fluctuations in a similar way as in the breakdown of the Taylor vortices in a turbulent Couette–Taylor flow at high Reynolds numbers.     

基于嵌入式以太网的异步电机矢量控制系统体系结构设计

为了实现异步电机现场控制与上层管理的无缝集成，提出在通用变频器一异步电动机调速系统的基础上，采用基于ARM7TDMI核的微控制器和以太网控制芯片，实现异步电机的网络化控制。详细介绍了该系统的体系结构设计方案。     

背景光光伏效应对屏蔽-光伏空间孤子的影响

在光伏晶体两端外加一恒定的直流偏压，背景光的光伏效应对形成屏蔽-光伏孤子的空间电荷场没有影响，但对晶体中的电流有影响.如果外电源的电动势是恒定的，则背景光的光伏效应与外电路的电阻协同起作用，可以通过晶体两端的电压降影响晶体中的空间电荷场，进而影响空间孤子的宽度.在一定的条件下甚至可以实现亮、暗孤子的转换. 关键词： 屏蔽-光伏 空间孤子 孤子宽度 亮暗孤子转换     

A New Pathway to Synthesize Cyclomercurated Ferrocenylimines Containing Heterocyclic Ring

The cyclomercurated ferrocenylimines containing heterocyclic ring were prepared by the condensation of cyclomercuration of acylferrocene with the appropriate heterocyclic amine.This procedure provides an efficient method for the synthesis of cyclomerucurated ferrocenylimines containing heterocyclic ring which are difficultly synthesized by the conventional method.The reaction mechanism is proposed.     

Two New Diterpene Acetylxylosides from Aster veitchianus

Two new acetylxylosides,ent-manool-13-O-β-D-2′-acetylxylopyranoside(1)and entmanool-13-O-β-D-2′,4′-diacetylxylopyranoside(2)were isolated from Aster veitchianus.Their structures were elucidated by spectroscopic methods.     

变换中含有孤立稳定点的第二积分换元定理

在不定积分第二积分换元定理的条件中,要求变换x=φ(t)不含有稳定点,即:φ′(t)≠0.当变换x=φ(t)中含有孤立稳定点时,给出了变换中含有孤立稳定点的第二积分换元定理.拓宽了第二积分换元定理的应用范围.     

KNSBN晶体猫式互抽动相位共轭光特性

在KNSBN：Ce晶体中，利用二波耦合作用，在单一光束无法获得相位共轭光的条件下，实现了“猫”式互抽运相位共轭光输出，获得较高的共轭光发射率，实验结果表明，晶体的二波耦合作用可以使晶体的自抽运相位共轭光的阈值光强降低。入射光的入射角范围增大，响应时间缩短。     

Surface rumpling of cubic CaTiO3 from density functional theory

In this paper, the structure of cubic CaTiO3 （001） surfaces with CaO and TiO2 terminations has been studied from density functional calculations. It has been found that the Ca atom has the largest relaxation for both kinds of terminations, and the rumpling of the CaO-terminated surface is much larger than that of TiO2-terminated surface. Also we have found that the metal atom relaxes much more prominently than the O atom does in each layer. The CaO-terminated surface is slightly more energetically favourahle than the TiO2-terminated surface from the analysis of the calculated surface energy.     

掺杂对碳纳米管拉曼光谱及场发射性能的影响

采用高温热解法在860℃分别制备出了镓、氮以及硼和氮掺杂的碳纳米管,提纯后利用丝网印刷工艺分别将它们制备成薄膜,并测试了它们的拉曼光谱与场发射性能。测试结果表明,掺杂纳米管的缺陷密集度比纯碳纳米管明显增大,而它们的场致电子发射性能则与掺杂元素的性质密切相关。镓和氮掺杂的纳米管均具有非常优异的场发射性能,而硼和氮共掺杂的纳米管的场发射性能很差。掺杂引起碳纳米管费米能级附近能态密度的变化及功函数的降低是其具有优异场致电子发射性能的主要原因。