~(211)At的色层分离和放射性扫描色谱测量

本文报道~(211)At的色层分离及其在FJ-2109型自动扫描色谱仪上的放射性测量方法。为了使测量达到最佳化,在二维“窗图”上选择道宽和扫描速度,有一个测量条件的狭窄区域给出好的放射性计数。这种实验设计和分析方法,既简便、快速且准确,适用于β或γ放射性核素的扫描色谱测量。 还研究了在1.2m回旋加速器上用27MeVα粒子束辐照Bi靶产生的~(211)At的吸附色层。在特制的石英蒸馏器中干法蒸馏,并经硅胶柱分离纯化使~(211)At得到最佳分离。~(211)At放射性薄层色谱和纸色层表明,二甲基甲酰胺的纸色层R_f大于用氯仿-乙醇以硅胶G,硅胶H或氧化铝为固定相的R_f。游离态的~(211)At或氧化Na~(211)At能制得~(211)At-屎嘧啶标记化合物,放射性产额依赖于~(211)At浓度,反应温度和时间。     

γ-Irradiation-induced changes at the electrical characteristics of Sn/p-Si Schottky contacts

We studied electrical parameters of Sn/p-Si Schottky barrier diodes (SBDs) by using in situ current-voltage (I-V) and capacitance-voltage (C-V) measurements under γ-irradiation at room temperature. The devices were held under zero bias during γ-irradiation with dose rate 0.25 kGy/h, and the total dose range was 0-45 kGy. Irradiation results indicated that these devices may have applications as radiation sensors in order to detect the low-energy γ radiation.     

甘蓝型油菜Bnl9070的表达与同源基因At2g19070的amiRNAi研究

基于原芯片杂交结果,油菜杂合双显性雄性核不育系差异表达基因Bnl9070与拟南芥At2g19070基因高度同源,在油菜可育株雄蕊中高量表达,不育株雄蕊中表达量极低。从雄性不育基因At2g19070入手,利用amiR—NAi（人工微RNA干扰）技术对其两个RNA区段分别设计靶标,转化拟南芥。在多个转基因拟南芥植株和后代中普遍观察到小孢子数量减少、成熟花粉萎缩失去活力、不结实或者少结实的不育表型。两个靶标的干扰使转基因拟南芥出现了类似的表型,基因表达抑制率都在90％以上,干扰效果好,暗示amiRNAi技术在靶标选择上具有一定的灵活性。At2g19070基因的干扰对Bnl9070的功能研究有借鉴作用。     

解读20世纪初的抽象艺术对建筑之影响

该文对20世纪初的抽象艺术观念和视觉语言进行了剖析,并以此为基础阐述现代主义建筑的"设计观念还原"和抽象艺术对建筑的影响所存在的两条路线。以期帮助学生从抽象艺术的角度展开对建筑的理解,对学生将艺术观念作为建筑创作源泉有所推动。     

冷却速度对铁素体-珠光体带状组织的影响机制

 通过建立模型,计算研究了冷却速度对铁素体-珠光体带状组织的影响机制,并通过试验验证了模型计算结果的正确性。结果表明：贫溶质区与富溶质区的Ar3温度差异是产生带状组织的前提条件,碳在贫溶质区产生珠光体之前的扩散距离是带状程度的决定因素。随着冷却速度的增大,贫溶质区与富溶质区的Ar3温度差增大,但碳扩散的距离减小,Ar3温度差对带状组织的影响也减小,带状程度减轻。     

基于At89S52单片机的智能客房控制系统

介绍了智能客房控制系统的结构、功能和特点。给出了以At89S52单片机为主控制器的客房控制器输入、输出硬件接口电路的设计,并对其特点做出阐述。结合控制系统的功能要求,对软件设计的程序流程及实现的基本过程进行了说明。     

Investigation of degradation mechanisms in PEM fuel cells caused by low-temperature cycles

Environmental influences, especially temperatures below the freezing point, can affect the performance and long-term stability of PEMFCs. Within the scope of this research, a completely new test procedure was developed to characterize PEMFC single cells with respect to their long-term stability at temperature cycles between 80 °C and ?10 °C. Using this procedure, the behavior of PEMFC single cells (active surface area of 43.6 cm²) with different cathode-ionomer-to-carbon (I/C) weight ratios (0.5/1.0/1.5) was evaluated. The generated in-situ measurement data clearly demonstrate that the performance of each PEMFC single cell changes individually as a function of the cathode I/C-ratio during the 120 stress cycles. While the MEA with an I/C ratio of 0.5 showed a power loss of ~1.49%, the MEAs with an I/C ratio of 1.0 and 1.5 showed a power loss of about ~7.75% and ~24.7%, respectively. The subsequent post-mortem ex-situ analyses clearly showed how the test procedure and the different I/C-ratios affected the changes in the catalyst layers (CL). The destructive mechanisms responsible for the changes can be divided into two categories: One part was driven by rapid enthalpy change leading to mechanical failure, and the other part, which led to the reduction of cathode CL thickness, was driven by rapid potential changes and potential shifts (overpotentials). This reduction in cathode CL thickness ultimately leads to an accumulation and excessive load of ionomer in the direction of GDL, resulting in a reduction in pore size, a shift in the core reaction area, and high O₂ transport resistance.     

Effect of ^211At treating pollen and stigma on generative cells and seed setting of rice

Low specific radioactivity (7.4kBq/ml) ^211At treating pollen and stigma can obviously affect morphological structures and physiological functions of pollen,stigma and ovule or embryo sac cells,and cause injury.Results showed that because of the radiation effects the seed setting rate of rice was decreased,and the development of some embryos were affected and others became abnormal.     

用全速电流测试方法检测PIC12F509微处理器

全速电流测试是一种新的电路测试方法。这里将一种指令级的全速电流测试方法应用到RISC指令集流水线结构的PIC12F509微处理器测试实验中。实验结果表明使用指令级的全速电流测试方法对PIC12F509微处理器进行测试是可行的。     

线性控制系统计算机仿真的编程探析

本文从系统的传递函数出发,介绍了一种基于幂级数计算的线性控制系统的计算机仿真的实用算法和编程技巧,并总结出这种算法的编程思路。