GaAs电介质表面对剥离电子通量分布影响的数值研究

利用半经典开轨道理论,研究了GaAs电介质表面对氢负离子在磁场中的光剥离干涉图样的作用,推导并计算了本体系下的光剥离电子流通量,主要研究GaAs电介质表面到离子的距离不同对电子通量的影响。结果表明,电介质表面到离子的距离可以改变电子通量分布中的振荡结构,影响探测平面上形成的干涉图样的分布。因此,可以通过改变电介质表面到离子的距离来调控剥离电子的通量和干涉图样分布。     

北京谱仪

北京谱仪是北京正负电子对撞机上的一台大型通用性磁谱仪.它由多种探测器组成,用于测量正负电子湮没后的遍举末态反应,进行粲粒子物理和τ轻子物理研究.它有大的覆盖立体角;优良的荷电粒子分辨;动量分辨和好的低能光子探测效率.本文对谱仪的结构和性能作了详细的描述.     

SETUP AND APPLICATION OF SCANNING NEAR-FIELD OPTICAL MICROSCOPY

The research on the setup and application of scanning near-field optical microscopy (SNOM) performed in our laboratory is reviewed in this report. We have constructed a versatile low temperature scanning near-field optical microscope with the capability of near-field imaging and spectroscopy, operating at liquid nitrogen temperature. A special designed coaxial double lens was used to introduce the illumination beam through a 200μm fiber; the detected optical signal was transmitted via a fiber tip to an avalanche photon detector. The performance test shows the stability of the new design. The shear force image and optical image of a standard sample are shown. A system of SNOM working at room temperature and atmosphere was used to characterize semiconductors and bio-molecular samples. It revealed the unique features of semiconductor microdisks in the near-field that is significantly different from that of far-field. The effects of different geographic microstructures on the near-field light distribution of InGaP, GaN, and InGaN multi-quantum-well microdisk were observed.     

高中生数学逻辑推理素养的培养研究

逻辑推理素养不仅是高中生数学学习必备的素养,而且是适应现代社会生活的基本素养.已有研究表明目前高中生的逻辑推理素养整体处于中等偏下的水平,所以研究关于如何提高高中生的数学逻辑推理素养这一问题是十分必要的.本文在简单说明逻辑推理素养内涵的基础上,以某些教育心理学理论为指导提出了几点逻辑推理素养的培养建议,并提供了两个教学实例以供参考.     

原料组成对针状焦结构的影响

在330–390℃、8 MPa、加氢时间为1.5 h和剂油比为1:40的条件下对中低温煤焦油原料进行加氢处理,得到精制原料后再通过热聚合煅烧等过程制得针状焦.通过元素分析、红外光谱(FT-IR)、气相色谱-质谱联用仪(GC-MS)等检测方法分析了精制原料组成,并采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)和偏光...     

Crystal growth and spectral properties of(Yb0.15Lu0.85xY0.85-0.85x)3Al5O12 single crystals

Four single crystals(Yb_0.15Lu_0.85xY_0.85-0.85x)₃Al₅O₁₂(x = 0, 0.25, 0.5, 1) were grown by the Czochralski method. The correlation of the host atom Lu:Y ratios with the density and the luminescence properties were revealed. The density increases linearly with increasing of Lu³⁺ content, which will improve the gamma ray cut-off ability. The integrated intensity of the X-ray excited luminescence spectrum increases exponenti...     

硅包覆上转换纳米晶制备和表征及生物特异性标记研究

以NaYF₄为代表的上转换纳米晶作为细胞及组织标记的研究越来越热。但易团聚,水溶性、生物兼容性差,没有与生物偶联官能团等缺点限制了其应用,因而表面修饰显得尤为重要。作者通过水热和共沉淀相结合方法,制备了NaYF₄∶Yb3+, Er3+上转换纳米晶,并对其包覆二氧化硅壳层。SEM表征硅包覆前后分别为25和250 nm的单分散粒子,说明硅已成功地包覆于纳米晶表面。980 nm激光照射下,样品的PBS胶体溶液呈可视上转换绿光。上转换荧光光谱和寿命均表明二氧化硅壳层对其发光性质影响很小。圆二色谱说明蛋白分子通过戊二醛与纳米晶偶联前后的二级结构基本不变。基于硅片上的抗原抗体荧光免疫识别试验进一步验证了偶联蛋白分子的特异性,表明该上转换纳米晶适合于生物标记。     

INFLUENCE OF THE DIPOLE-DIPOLE INTERACTION BETWEEN ATOMS ON THE PHASE PROPERTIES OF LIGHT

The time evolution and the statistic characteristic of the light phase in the Tavis-Cummings (T-C) model of two identical two-level atoms coupled to a strong coherent light field are studied by means of the Pegg-Barnett phase theory. It is proved that the dipole-dipole interaction between atoms will lead to the frequency shift of light, the weakening of the degree of atom-field coupling and the restraint of light phase diffusion.     

碳-13核磁共振法研究小皮伞多糖结构

采用＾１３Ｃ核磁共振法测定和确定了小皮伞多糖中的大分子葡聚糖,葡甘聚糖等３种多糖的一级结构,这些结果与组成分析和甲基化分析结果是一致的,确定了毫克级直接用＾１３Ｃ核磁共振法分析和检测多糖结构的方法。     

N1-(四氢呋喃-2-基)-N3-烷基巯基烷基-5-氟尿嘧啶

N1-(四氢呋喃-2-基)-N3-烷基巯基烷基-5-氟尿嘧啶及其氧化产物…….