品味算法的"交汇性"(续)

(接20101-12(上)P33) 例12 (2010年苏州市调考题)程序框图如图13所示,已知曲线E的方程为ax2+by2=ab(a,b∈R),若该程序输出的结果为s,则 A.当s=1时,E是椭圆 B.当s=-1时,E是双曲线 C.当s=0时,E是抛物线 D.当s=0时,E是一个点解析 若a=0,b=1,则s=0.此时ax2+by2=ab变为y2=0,即y=0,表示直线,排除C、D两项;若a=-1,b=-1,则s=1.此时ax2+by2=ab变为x2+y2=-1,不表示任何曲线,排除A项.故选B.图14点评本题是程序框图与解析几何的交汇综合题,利用特值验证并结合筛选法容易得出正确结果,这正是命题者的初衷和"得意"之处.     

基于磁性免疫结合CdSe/ZnS纳米粒子化学发光放大的脱落酸检测方法

脱落酸作为一种重要的植物激素,在调节植物对环境应激性,控制种子发芽、植物生长、气孔开闭等方面起着关键作用.随着脱落酸信号传导研究的深入,亟需一种快速、灵敏的脱落酸分析检测方法.我们发展了一种简化的磁性免疫分析方法,结合CdSe/ZnS纳米粒子放大化学发光信号,实现了脱落酸的高灵敏检测.在最优条件下,本方法只需30min便可得到检测结果,脱落酸的检测范围为1pM到10nM.我们还考察了剂量效应对磁性微球准均相体系在实际应用中产生的影响.本方法对脱落酸具有高灵敏度和高选择性,有望发展成对植物激素普遍适用的分析方法.     

Adiabatic Deutsch-Jozsa Problem Solved by Modifying the Initial Hamiltonian

We present an alternate adiabatic evolution for the Deutsch-Jozsa problem. The biggest difference of our adiabatic evolution constructed here with those appearing before is that an alternate initial Hamiltonian is used for the adiabatic evolution, with which the evolution task can be finished in O（1） time complexity. Our construction mostly resembles the one discussed by Das et al. [Phys. Rev. A 65 （2002） 062310], except for the initial system Hamiltonian of the adiabatic algorithm.     

Photoacoustic Imaging of Animals with an Annular Transducer Array

A photoacoustic system with an annular transducer array is presented for rapid, high-resolution photoacoustic tomography of animals. An eight-channel data acquisition system is applied to capture the photoacoustic signals by using multiplexing and the total time of data acquisition and transferring is within 3 s. A limited-view filtered back projection algorithm is used to reconstruct the photoacoustic images. Experiments are performed on a mouse head and a rabbit head and clear photoacoustic images are obtained. The experimental results demonstrate that this imaging system holds the potential for imaging the human brain.     

KD-S型SiC纤维表面BN界面层Raman光谱研究

由于SiC纤维具有高强度、高模量、强抗化学腐蚀性等优越性能,因此广泛用于陶瓷基复合材料的增强当中。但在高温下制备复合材料,容易使纤维与基体之间形成牢固的附着力,导致复合材料力学性能差,因此需要界面层使纤维与基体间的结合足够弱。BN具有良好的耐热性、抗氧化性和微裂纹自愈合能力,可用于解决SiC纤维增强SiC基复合材料的界面问题。CVD法是常用的制备BN界面层的工艺方法。本文以BCl3-NH_3为原料,在较低温度下通过CVD工艺制备了BN界面层。     

基于单片机的开关电源并联供电系统的设计

针对并联供电中各电源模块参数的分散性,导致输出电流的不均衡,结果分担电流多的模块热应力大,降低了系统的可靠性等问题,提出了具有均流技术的开关并联供电系统的设计.     

红外光声光谱技术应用于复合膜的原位剖面分析

土壤颗粒在微观尺度上具有明显的异质性,表现为土壤有机质与矿物质的双层复合物结构。本研究以人工制备的复合膜样本为材料,采用红外光声光谱技术和独立成分分析对复合膜样本层进行原位剖面分析。复合膜样本由PE保鲜膜和办公胶带制备,红外光声光谱仪动静速率分别为0.16,0.32和0.64 cm/s。结果表明,通过改变光谱仪动静速率可以原位获取复合膜样本不同深度的组成信息,并估测出PE膜的厚度为5.4~7.6μm,与实际厚度(7±1)μm相接近;同时利用独立成分分析可以直接从复合膜样品的红外光声光谱中,同时分离出PE保鲜膜和胶带的光声光谱特征。红外光声光谱技术可对复合膜进行剖面分析,为进一步研究异质性土壤样本,特别是有机矿质复合体样本提供了新的分析手段。     

Continuous zircon-type tetragonal Y Bi0.95-xVO4： 0.05Dy^3＋ solid solution： synthesis,characterization, and optical properties

We synthesize continuous solid solutions with monophasic zircon-type structure of vanadates of formula YxBi0.95 VO4：0.05Dy^3＋ （x = 0-0.95） using a combined method of co-precipitation and hydrothermal synthesis. The X-ray diffractometer patterns confirm the formation of a solid solution of YBi0.95-xVO4：0.05Dy^3＋, and the results show that all the samples have monophasic zircon-type structure. The absorption spectra of the prepared phosphors show a blue-shift of the fundamental absorption band edge with increasing Y^3＋ content. An intense tunable characteristic emission of Dy^3＋ is observed with the increasing ratio of Y/Bi. Finally, the mechanism of luminescence of Dya＋ in the YBi0.95 VO4：0.05Dya＋ （x = 0-0.95） solid solution is analyzed and discussed.