宁波市2008~2012年手足口病时空聚集性分析

以街道/镇/乡为基本空间单位, 采用时空扫描统计量对宁波市2008~2012年手足口病的时空聚集性特征进行分析. 结果显示: 2009~2012年宁波均出现了有统计学意义的一级时空聚集区, 聚集区的相对风险介于3.76~5.37, 即聚集区内是聚集区外手足口病发病风险的约3~5倍. 时空聚集性出现的主要区域为宁海和象山的绝大多数街道/镇/乡. 宁海和象山是宁波市手足口病的发病热点地区, 需要采取针对性措施进行重点防控.     

磁共振弥散成像与超声弹性成像在前列腺穿刺活检中的应用价值

本研究探讨磁共振弥散成像(DWI)与超声弹性成像(UE)在前列腺穿刺活检中的应用价值.112例疑似前列腺癌(PCa)患者中,经前列腺活检病理穿刺证实为阳性(PCa) 59例、阴性(前列腺良性增生)53例.经研究发现,前列腺穿刺活检穿刺阳性患者超声弹性评分高于阴性患者,表观扩散系数(ADC)值低于阴性患者,二者均为前列腺...     

Occurrence and elimination of in-plane misoriented crystals in AlN epilayers on sapphire via pre-treatment control

AlN epilayers are grown directly on sapphire(0001)substrates each of which has a low temperature AlN nucleation layer.The effects of pretreatments of sapphire substrates,including exposures to NH3/H2and to H2only ambients at different temperatures,before the growth of AlN epilayers is investigated.In-plane misoriented crystals occur in N-polar AlN epilayers each with pretreatment in a H2only ambient,and are characterized by six 60°-apart peaks with splits in each peak in(10ˉ12)phi scan and two sets of hexagonal diffraction patterns taken along the[0001]zone axis in electron diffraction.These misoriented crystals can be eliminated in AlN epilayers by the pretreatment of sapphire substrates in the NH3/H2ambient.AlN epilayers by the pretreatment of sapphire substrates in the NH3/H2ambient are Al-polar.Our results show the pretreatments and the nucleation layers are responsible for the polarities of the AlN epilayers.We ascribe these results to the different strain relaxation mechanisms induced by the lattice mismatch of AlN and sapphire.     

Generating monoenergetic proton beam by using circularly polarized laser

The interaction of ultrashort intense circularly polarized laser with ultra thin overdense foil is studied by particle-in-cell simulation and analytic model. It is found that with the balance between pondermotive force and electrostatic force, highly quasi-monoenergetic proton beam can be generated by Phase Stable     

无人机载小型多光谱成像仪的设计

多光谱成像仪足一种有效的对地观测工具,航空机载多光谱成像仪在遥感领域得到广泛的应用。介绍一种新的小型多光谱成像仪的设计,以小型化、轻量化研究为特点,使其与小型无人飞机精密结合,成为一种灵活机动的海洋监测工具,将在海洋污染、赤潮发现、原油泄漏等重大事件临测上发挥作用。     

Hopping Conductivity in a Single-Walled Carbon Nanotube Network

We investigate the resistance and magnetoresistance （MR） of an entangled single-walled carbon nanotube （SWNT） network. The temperature dependence of conductance is fitted by formula G（T） = Go exp[-（To/T）^1/2] with To = 15.8 K at a wide temperature range from 4 K to 300K. The MR defined by [R（T, H） - R（T, 0）]/ R（T, 0） as a function of temperature and magnetic field perpendicular to the tube axis is negative at low temperatures. The MR amplitude increases as the temperature decreases at relative high temperature, but becomes decrease when temperature below 4 K. The results are explained in terms of the coherent hopping of carriers in the presence of a Coulomb gap at low temperature.     

疲劳短裂纹萌生及发展的细观过程和理论

本文综述了疲劳短裂纹研究的进展和现状,包括关于短裂纹的属性,短裂纹萌生和发展的细观过程以及描述短裂纹行为的若干模型。      

GaAs／GaAlAs激光器列阵有源区电场分布研究

用连续波电光检测法测量了激光器列阵发光区电场分布，并对其注入电流扩展了模拟讨论。     

荧光俘获效应对Er3+/Yb3+共掺杂碲钨酸盐玻璃光谱性质的影响

制备了掺杂浓度相同而厚度不同的Er^3 ／Yb^3 共掺杂碲钨酸盐玻璃样品,测量了样品的吸收光谱和970nmLD激发下的Er^3 离子1．5um发射的荧光光谱和荧光寿命,计算了Er^3 离子的发射截面,研究了荧光俘获效应对Er^3 离子1．5um发射的光谱性能的影响。结果表明,样品中Er^3 离子存在很强的荧光俘获效应,且荧光俘获效应随样品厚度的增加而增强。荧光俘获效应使测得的荧光寿命比计算的自发辐射寿命要长,随样品厚度的增加,Er^3 离子1．5um发射的荧光寿命增加;其荧光有效线宽△λeff与次峰值强度和主峰值强度的比值,Ⅰa/Ⅰp也增加,且△λeff与Ⅰa／Ⅰp存在很好的线性关系。首次提出采用Er^3 1．5um波段荧光谱的次峰值强度和主峰值强度的比值,Ⅰa／Ⅰp与从McCumber理论计算得到的次峰值发射截面和主峰值发射截面的比值(σea／σep)的差值或比值来判断基质中Er^3 1．5um波段荧光俘获效应强弱的方法。     

导数-比导数紫外分光光度法同时测量水样中硝酸根和亚硝酸根的含量

在不需分离和掩蔽的条件下,在导数间隔因子为10nm,测量波长在200、210、220nm时,用导数-比导数法同时测定光谱重叠严重的水样中NO~-_2和NO_3~-含量,二者测定的标准回收率在95%—105%,6次测定的相对标准偏差小于3%,NO_2~-的浓度在0—13mg/L,NO~-_3的浓度在0—10mg/L符合线性关系。