沉淀二氧化硅消光剂的制备研究

涂料中的消光剂是一类能够改变涂膜表面光学性能的助剂。这类助剂能够在涂膜表面产生预期微粗糙度,使涂膜的光泽显著降低,给人一种古朴典雅的感觉。近几年来,我国的涂料工业方兴未艾,涂料总产量也跃居世界的前列。在这期间高光泽的亮光涂料以其色泽鲜艳、明亮等优点深受消费者的喜爱,并在相当长的时间内一统着涂料市场[1]。但是,随着人们生活水平的不断提高,一方面消费者感觉到了高光泽的亮光涂料成膜后反光比较严重,对人的眼睛有害;另一方面消费者的审美观念越来越倾向于休闲、时尚和个性化。这些因素就导致了人们对具有柔和外观的低光泽涂…     

新型DPA类似物的合成及其对结核杆菌H37 Rv的抑菌性能

以D-阿拉伯构型的双环\[3.1.0\]己基胺和脂质醛为原料,通过还原胺化合成了6个新的癸异戊烯磷酰基-β-D-阿拉伯呋喃糖（DPA）类似物,其结构经¹H NMR、 ¹³C NMR和HR-MS(ESI)表征。利用MTT法检测了化合物对结核杆菌H37Rv的抑菌性能。结果显示化合物在1 mg·mL^-1时没有明显抑菌活性。     

Magnetotransport Properties of a Nodal Line Semimetal TiSi

We report the magnetoresistance(MR), de Haas-van Alphen(dHvA) effect and Hall effect measurements on a single crystal of TiSi, which is predicted to be a nodal line semimetal. With application of a magnetic field, a metal-to-insulator-like transition in ρ(T) and a nonsaturating MR are observed at low temperatures. The dHvA oscillations reveal a small Fermi-surface pocket with a nontrivial Berry phase. The analysis of the nonlinear Hall resistivity shows that TiSi is a multiband system with low carrier densities and high mobilities. All these results unambiguously prove the existence of Dirac fermions in TiSi.     

超高灵敏度太赫兹超导探测技术发展

太赫兹波段占有宇宙微波背景(CMB)辐射以后宇宙空间近一半的光子能量,该波段在天文学研究中具有不可替代的作用,因此太赫兹天文学的研究,具有极其重要的科学意义。本文系统介绍了基于超高灵敏度太赫兹超导探测技术的太赫兹相干探测器发展状况,包括超导隧道结混频器(SIS)和超导热电子混频器(HEB),以及以超导动态电感探测器(MKIDs)和超导相变边缘探测器(TES)为代表的非相干探测器的研究。在此基础上,展望了该领域未来发展趋势,对我国太赫兹天文探测技术的发展具有一定的参考意义。     

石墨炉原子吸收光谱法测定山药中的铅

收集6种不同来源的山药样品,使用浓硝酸-浓高氯酸(4∶1,V/V)混合溶液进行消解,用石墨炉原子吸收光谱法测定山药中Pb含量.山药样品中Pb含量不高于0.854mg·kg-1.方法学考察加标回收率为95.00％,其RSD为3.14％.6种山药样品中铅含量均符合国家《药用植物及制剂进出口绿色行业标准》的限量指标(Pb≤5mg·kg-1).测定方法快速、灵敏,数据准确可靠.     

例说初中数学教学中『问题串』设计的『四化』

问题串是指在一定的学习范围或主题内,围绕一定目标、按照一定逻辑结构精心设计的一组问题使用问题串进行教学实质上是引导学生带着问题(任务)进行积极的自主学习,由表及里,由浅入深地自我建构知识的过程那么,在课堂教学中如何创设有效问题串,提高课堂效率?本人结合教学实践,从以下四个方面谈一些感想.     

Effects of Different Zernike Terms on Optical Quality and Vision of Human Eyes

The visual quality of human eyes is much restricted by high-order aberrations as well as low-order aberrations （defocus and astigmatism）, but each term of high-order aberrations contributes differently. The visual acuity and contrast of the image on the retina can be gained by inducing aberrations to each term of high orders. Based on an adaptive optics system, the visual acuity of four subjects is tested by inducing aberrations to each Zernike term after correcting all the aberrations of the subjects. Zernike terms near the center of the Zernike tree affect visual quality more than those near the edge both theoretically and experimentally, and 0.1μm aberration of these terms can clearly degrade the optical quality and vision. The results suggest that correcting the terms near the center of Zernike tree can improve the visual quality effectively in practice.     

Image registration based on matrix perturbation analysis using spectral graph

We present a novel perspective on characterizing the spectral correspondence between nodes of the weighted graph with application to image registration. It is based on matrix perturbation analysis on the spectral graph. The contribution may be divided into three parts. Firstly, the perturbation matrix is obtained by perturbing the matrix of graph model. Secondly, an orthogonal matrix is obtained based on an optimal parameter, which can better capture correspondence features. Thirdly, the optimal matching matrix is proposed by adjusting signs of orthogonal matrix for image registration. Experiments on both synthetic images and real-world images demonstrate the effectiveness and accuracy of the proposed method.     

CdSe薄膜的制备及性能表征

室温下,以CdSO4H1SeO3和Na2SO4为原料,采用二电极体系,利用电化学法在ITO玻璃基底上沉积了CdSe薄膜.采用高分辨x射线衍射仪(HRXRD)、场发射扫描电镜(FESEM)、原子力显微镜(AFM)、紫外.可见.近红外(UV-VIS-NIR)分光光度计、荧光分光光度计(PL)对不同沉积电压下所制备的薄膜的晶体结构、形貌及光学性能进行分析表征.结果表明:所制备的薄膜为立方相CdSe,呈纳米颗粒状,部分粒子表现出不均匀团聚.紫外吸收光谱的吸收峰较体相CdSe有较大的蓝移,且导致禁带宽度发生改变,表现出量子尺寸效应.样品发射光谱表现出荧光现象,且单色性好.适当的沉积电压对CdSe薄膜的形貌和质量起关键作用,同时讨论了其反应机理.     

在线净化加速溶剂萃取–气相色谱–质谱法测定土壤中11种半挥发性有机物

采用加速溶剂萃取法对样品进行在线净化和萃取,气相色谱–质谱法测定土壤中11种半挥发性有机物.考察了净化条件、萃取剂、浓缩条件等因素对土壤中11种半挥发性有机物测定的影响,分析了在线净化和离线净化的差异以及在线净化的优势.以弗罗里硅土和石墨化碳黑为净化剂,石英砂为分散剂,土壤样品经快速溶剂萃取仪在线净化萃取,浓缩后采用气...