共查询到19条相似文献,搜索用时 93 毫秒
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引言 自从X射线被发现以后,X射线分析法在很多领域获得了应用。而今,在水泥工业生产和研究实验中,也已获得进一步的发展。利用x射线衍射(XRD)可以进行物质结构和物相分析,利用x射线荧光(XRF)可以进行元素分析。在水泥工业中,用于工艺和质量控制的X射线最新分析系统表现出的主要优点是:样品制备工作量极小、测量时间短、分析灵活方便、可重复再现性高,并能充分与现代化的工艺技术相结合。 在过去几十年中,X射线分析法经过几大发展阶段后,性能更加优良,应用更加广泛。在这之中,除了分析效率大大提高以外, 相似文献
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目前通用的各种X射线荧光分析方法是以比较式样和标样(一个或几个)的分析线的测量强度为基础,把测量标样所获得的数据拟合成一条光滑曲线,一般最好与最小二乘法曲线相吻合。如果基体效应严重,则可用简单的校准法(也就是分析线强度随浓度的变化)进行准确分析。如果基体效应严重,但分析成分的浓度范围很小,且标样与试样很相似,也采用上述方法。而这类自动化分析过程所采用的分析软件,大多有以下3个步骤。 相似文献
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闪烁体是X射线成像技术中的核心器件,它能将吸收的高能射线(X射线或其他高能带电粒子)转化为可见光,已被广泛应用于医疗诊断、辐射剂量测定和安全检查等领域。目前大多数的商用闪烁体为单晶或薄膜材料,不仅制备工艺复杂、生长周期长、成本高,并且辐照稳定性差,成像效果不佳。通过在透明玻璃基体内原位析出Zn S量子点,探索Zn S量子点微晶玻璃(GC)作为一种成本低、耐候性强的闪烁体在X射线间接成像领域的应用。实验结果表明,在X射线辐照下ZnS GC的发射峰位于518 nm,并利用X成像系统对鱼骨骼和芯片进行成像,由于ZnS量子点在玻璃基体中的均匀分布,结果显示图像轮廓清晰、物体内部结构分明,并且成像分辨率达到18.0 lp/mm。此外,在累积剂量高达288 J/kg的情况下,损坏的ZnS GC闪烁体可通过简单的热处理完全恢复成像性能。ZnS GC作为闪烁体在高分辨X射线成像领域表现出广泛的应用前景。 相似文献
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X射线荧光光谱法(XRF)是应用比较早且至今仍在广泛应用的一种元素分析技术。因其具有分析速度快、精度高、灵敏度高、重现性好、分析元素范围广等优点,广泛的应用于矿石样品的成分分析。本文对X射线荧光光谱法(XRF)进行了概述,并对其在几种常见矿石样品分析中的应用进行了综述。 相似文献
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Jincheng Xiong Huixia Zhang Linqian Qin Shuai Zhang Jiyue Cao Haiyang Jiang 《International journal of molecular sciences》2022,23(8)
The presence of food contaminants can cause foodborne illnesses, posing a severe threat to human health. Therefore, a rapid, sensitive, and convenient method for monitoring food contaminants is eagerly needed. The complex matrix interferences of food samples and poor performance of existing sensing probes bring significant challenges to improving detection performances. Nanocomposites with multifunctional features provide a solution to these problems. The combination of the superior characteristics of magnetic nanoparticles (MNPs) and quantum dots (QDs) to fabricate magnetic fluorescent quantum dots (MNPs@QDs) nanocomposites are regarded as an ideal multifunctional probe for food contaminants analysis. The high-efficiency pretreatment and rapid fluorescence detection are concurrently integrated into one sensing platform using MNPs@QDs nanocomposites. In this review, the contemporary synthetic strategies to fabricate MNPs@QDs, including hetero-crystalline growth, template embedding, layer-by-layer assembly, microemulsion technique, and one-pot method, are described in detail, and their advantages and limitations are discussed. The recent advances of MNPs@QDs nanocomposites in detecting metal ions, foodborne pathogens, toxins, pesticides, antibiotics, and illegal additives are comprehensively introduced from the perspectives of modes and detection performances. The review ends with current challenges and opportunities in practical applications and prospects in food contaminants analysis, aiming to promote the enthusiasm for multifunctional sensing platform research. 相似文献
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石墨烯量子点(GQDs)作为石墨烯家族的最新一员,除了继承石墨烯的优异性能,还因量子限制效应和边界效应而显现出一系列新的特性,引起了化学、物理、材料和生物等各领域科研工作者的广泛关注。GQDs的制备方法通常分自上而下和自下而上的方法。对其各种制备方法和应用分别进行了介绍,并结合各种应用对GQDs的要求给出了制备方法的建议。指出了GQDs研究中存在的问题及发展方向。 相似文献
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在氩气条件下和非配位溶剂十八烯(ODE)中,利用单质Se和CdO在油酸(OA)配体中,高温成核,低温增长合成量子点CdSe。利用紫外吸收光谱和荧光对量子点进行表征和分析,初步产物的荧光谱图呈现两个荧光发射峰,分别为短波处较窄的带边发射和长波处较宽的缺陷发射。利用一种修饰剂对量子点表面进行修饰,有效的消除缺陷发射,修饰后的量子点在荧光谱图中表现为仅有一个发射峰位,峰位处于410nm左右。在紫外灯照射下显示紫色。 相似文献
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Ronit Freeman Julia Girsh Bilha Willner Itamar Willner 《Israel journal of chemistry》2012,52(11-12):1125-1136
Due to an internal error, the following article was added after the original publication of the special issue on Nanochemistry (11-12/2012). Semiconductor quantum dots (QDs) exhibit unique photophysical properties, turning these nanomaterials into ideal components for the development of optical or optoelectronic sensors and biosensors. Various methods and mechanisms of using QDs for sensing have been implemented, including the probing of recognition events by the luminescence of the QDs, their application in fluorescence resonance energy transfer (FRET), electron transfer (ET), chemiluminescence resonance energy transfer (CRET), and photoelectrochemical generation of photocurrents. These different mechanisms are exemplified by discussing the QD-based sensing of low-molecular-weight substrates, chiroselective sensing of amino acids, probing of the catalytic activities of enzymes (casein kinase, tyrosinase, NAD+-dependent enzymes), and analysis of DNA and of aptamer-substrate complexes. Specifically, the amplified QD-based sensing of DNA using exonuclease III as target regeneration biocatalyst and the multiplexed detection of DNAs using differently sized QDs are discussed. Also, the implementation of the CRET process for the multiplexed analysis of DNA using differently sized QDs is addressed. Finally, the use of semiconductor QDs for the photoelectrochemical detection of DNA, aptamer-substrate complexes and enzyme activities are discussed. Specifically, the use of QDs for photoelectrochemical sensors, using the CRET process as internal excitation light source, is described. The future applications of the various QD-based sensors as analytical devices and as nanotools that probe intracellular processes are discussed. 相似文献