低维半导体异质结中的量子相干红外发射机理理论研究

给出了一种在非粒子反转条件下量子阱和量子点激光器的红外发射机理.此种红外发射是基于在同一作用区产生并作为红外场相干源的两种带间跃迁激光场的共振非线性混合.这种频率下转换机理并不依赖于在半导体激活媒质中的长时相干假定条件,在室温和泵注入电流条件下仍然有效.频率下转换的固有效率可以达到相当于每个可见光子产生一个红外光子的量子极限值.根据红外发射的可参变特性,这种非粒子反转的方法尤其适用于长波红外工作范围.     

Three-dimensional size and orientation of the precipitates in AZ91 magnesium alloys measured by TEM techniques

Knowledge of the microscopic structure, including three-dimensional (3-D) size and orientation of the precipitates, is essential to fully understand the mechanical properties of the magnesium alloys and designing the alloys with better performance. Analytical TEM with high spatial resolution offers the simultaneous measurements of 3-D size, structure, orientation, composition of the precipitates from one typical sample along an established crystallographic axis. Besides popular Burgers orientation relationship (OR), other ORs such as Pitsch--Schrader OR, Crawley OR, Potter OR and a new OR with the form of [0001]_α 1.0° from [311]_γ and (11\bar 20)_α 2.0° from (03\bar 3)_γ between the magnesium matrix and the precipitate γ -Mg₁₇Al₁₂ are identified by TEM imaging and diffraction techniques. As a case study, the thicknesses of the individual precipitates with Burgers OR are further measured to be 100--200~nm through both electron energy-loss spectroscopy and x-ray energy dispersive spectroscopy combining differential x-ray absorption and extrapolation, which are in agreement with the overall 3-D size statistic distribution results obtained through analysing various samples along various directions. Furthermore, the fabricated wedge-shape structure provides a platform on which to study the dependence of the interfacial strain on the variation of the thickness.     

吸附式叶栅代替串联叶栅气动可行性探索

本文首先以ONERA串列叶栅为研究对象,利用数值模拟的方法对串列叶栅特性及其内部流动进行了分析,在此基础上,设计了与串列叶栅具有同等性能的单列吸附式叶栅,并在设计工况和非设计工况下对改型后的单列吸附式叶栅特性及其内部流场进行了详细分析.结果表明:在相同来流马赫数、出口条件和扩散因子的情况下,单列吸附式叶栅的性能优于串列叶栅,在高负荷压气机设计中用吸附式单列叶栅代替串列叶栅的做法是可行的.     

Measurements of aerosol distribution by an elastic-backscatter lidar in summer 2008 in Beijing

Elastic lidar observations of profiles of the aerosol extinction, backscattering coefficients, and the lidar ratio have been performed in Beijing. The elastic lidar transmitts wavelengths of 532 and 355 nm. The measurement altitude can reach up to 6 km. The similarity of the extinction and baekscattering profiles suggests a close relation between the mean transmission and reflection properties. The lidar ratio on July 22, 2008 varied from 10 to 30 sr with the mean value of 20 sr. The profiles of the aerosol properties indicate the cirrus at 6 km altitude and a well-mixed boundary layer from July 22 to 24, 2008. The detected boundary layer also agrees well with the high and stable ozone concentration obtained from the differential optical absorption spectroscopy （DOAS） system.     

氨基酸与四氰代苯醌二甲叉的荷移反应的研究

本文用分光光度法研究了 6种氨基酸与四氰代苯醌二甲叉 (简称TCNQ)之间的荷移反应。测定了配合物的不稳定常数 ,讨论了配合物的组成。考察了形成配合物的影响因素 ,确立了最佳反应条件 ,并测定了味精中谷氨酸钠的含量 ,结果令人满意     

COIL中稀释气体对单态氧产率影响的实验研究

 利用自发Raman散射光谱对射流式氧发生器的单态氧产率进行了测试，研究了稀释气体对于发生器产率的影响，并分析了造成影响的原因     

蒙成药如达多糖的研究

从蒙成药如达中提取水溶性多糖,硫酸-苯酚法测定其含量。平均回收率为99.8%,RSD为0.94%。GC测定了水溶性多糖的组成为葡萄糖、半乳糖和甘露糖。其摩尔比为:6.33:3.25:1.59。     

用GSP进行"波动"教学案例

学生的学习需求是指学生要达到的目标水平与他现在实际水平之间的差距．本课的教学目标是：了解波的形成条件及过程、波的种类、振动和波的关系；理解波的传播规律和波的图象．学生的实际是只学过振动和振动的图象，会使用《几何画板》软件．此差距很明显．这就要求教师根据建构主义学习理论，通过创设情景、搭脚手架来降低知识的梯度，真正把教学目标转化为学生自己的学习需求．     

3,7-二硝基亚氨基-2,4-二氮杂双环[3,3,0]辛烷的放热分解反应动力学

在程序升温条件下 ,用DSC研究了标题化合物的放热分解反应动力学 .用线性最小二乘法、迭代法以及二分法与最小二乘法相结合的方法 ,以积分方程、微分方程和放热速率方程拟合DSC数据 .在逻辑选择建立了微分和积分机理函数的最可几一般表达式后 ,用放热速率方程得到相应的表观活化能 (Ea)、指前因子 (A)和反应级数 (n)的值 .结果表明 :该反应的微分形式的经验动力学模式函数、Ea 和A值分别为 (1-α) 0 .44、2 30 .4kJ/mol和 10 18.16s-1.借助加热速率和所得动力学参数值 ,提出了标题化合物放热分解反应的动力学方程 .该化合物的热爆炸临界温度为 30 2 .6℃ .上述动力学参数对分析、评价标题化合物的稳定性和热变化规律十分有用 .     

土壤重金属铬元素的激光诱导击穿光谱定量分析研究

利用Nd ∶YAG脉冲激光器(波长:1064 nm)作为光源,在实验室自然大气环境下诱导产生土壤激光等离子体,通过等离子体原子发射光谱法定量分析了国家标准土壤样品中元素Cr的含量.实验上研究了在最佳实验条件下土壤中Cr的LIBS分析谱线,测定了Cr元素的定标曲线.实验结果表明,Cr元素浓度在(60—400)×10^-6范围内,元素含量与光谱线强度之间有较好的线性关系;元素Cr浓度分析测量的相对标准偏差(RSD)为7.89%,定量分析结果与标准值的相对偏差为5.3%,Cr元素的检测限为1 关键词： 土壤污染 定量分析 激光诱导击穿光谱 定标曲线