共查询到19条相似文献,搜索用时 125 毫秒
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为评价放射性同位素测量的精度 ,对美国BeckmanLS 65 0 0ScintillationSystem的单标DPM(SLDPM)和AUTODPM两种猝灭校正方法进行了比较。结果显示 ,SLDPM的猝灭校正范围宽(校正范围由校正曲线决定 ) ,猝灭校正精度高 ,并且可以用于测试双标或三标的样品。使用AU TODPM猝灭校正方法进行测试 ,对于低能β射线3H ,在 90 相似文献
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相较于传统无机半导体材料,有机共轭聚合物半导体具有响应光谱高度可调、质量轻、可大面积制备、与柔性基板兼容等优点,其作为光活性层在下一代可穿戴光电探测器的应用中显示出巨大的应用潜力.共轭聚合物具有多样化的结构设计,不同的分子结构对其光物理化学性能可进行灵活调控,进而展现出各具特色的光电特性.同时,通过结构优化亦可赋予共轭... 相似文献
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美国科学家最近开发出一个微型纳米探测器,能够探测活细胞中的致癌毒素或追踪癌症药物的效用。这是一个追踪身体内特定化学药物的全新工具。该研究成果发表在2008年12月14日的《自然.纳米技术》杂志上。研究人员把碳纳米管植入DNA分子内制成传感器,以便置入活细胞内。该传感器可以探测多种特定的损害DNA的物质,比如某些毒素分子、自由基以及一些癌症化疗药物分子。它能定位这些分子在细胞内的准确位置,尤其对于过氧化氢这种氧化剂,其探测精度可以达到单个分子。美国麻省理工学院研究小组开发的传感器将成型的碳纳米管与DNA包裹在一起,使其能与细胞内损伤DNA的“代理”相结合。该传感器能发出可在近红外线光谱附近被探测到的荧光,因为人体组织在这个光谱内不会发光,纳米管因此显得很突出。当传感器同细胞内的DNA相互作用时,光信号发生变化,这些变化能够帮助研究人员识别特定的分子。因为该传感器被涂在DNA内,它们能够被安全地注射进活细胞内。最终,细胞吞噬掉涂层表面的蛋白质,探测器就能“脱颖而出”。这种细胞“探测器”可用于癌症患者的化疗监测,确保化疗药物有效发挥作用。研究人员解释说,有很多化疗药物都会对细胞内的DNA产生极强的破坏力,引发严重副... 相似文献
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制备了石墨炔修饰的金属-半导体-金属结构的ZnO紫外探测器,研究了不同旋涂次数的石墨炔修饰对探测器性能的影响。实验结果表明,石墨炔修饰的探测器比未修饰器件的光电流提高4倍,暗电流降低2个数量级,同时探测器的响应度和探测率也明显提高,其中旋涂2次的石墨炔修饰的器件特性为最优。在10 V偏压下,旋涂2次的石墨炔修饰的探测器响应度高达1759 A·W−1,探测率高达4.23× 1015 Jones,这是迄今为止报导过的溶胶-凝胶法制备的ZnO紫外探测器的最高值。经过对探测器各项性能的测试分析可知,石墨炔修饰的ZnO探测器性能的提高归因于石墨炔良好的空穴传输特性。暗环境下ZnO与石墨炔界面处形成p-n结,使探测器的暗电流大幅降低;光照条件下光生空穴在石墨炔中聚集,减少了电子空穴对的复合,有效提高了器件的光电流。由于石墨炔修饰减少了ZnO表面的氧分子吸附和解吸附过程,器件的响应速度也明显加快。 相似文献
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近红外及短波红外光探测器在热成像、夜视、农业视察、生物识别传感和遥感等相关领域具有重要的应用。然而目前大多数商用的红外光探测器需要额外的制冷设备辅助,并且器件不可弯折,很大程度上限制了它的应用。为了解决这些问题,近年来涌现了越来越多有关有机半导体的研究。有机半导体不仅具有可精细调控的带隙、高的吸光系数和机械柔性等优点,并且能够通过“卷对卷”工艺实现大面积制备并与柔性基底兼容。基于有机半导体的红外光探测器无需额外的制冷设备且具有无机红外光探测器所不具备的诸多特点,因而很有希望用于发展下一代红外光探测技术。本综述首先介绍了有机近红外及短波红外光探测光电晶体管、光电二极管器的基本原理,其次介绍了近年来兴起的有机半导体复合材料及其新颖的器件结构,接着总结了有机红外光探测器在电子眼、人工突触、以及可穿戴实时健康监测等应用的最新进展。最后,讨论了这一领域存在的挑战并对其未来发展进行了展望,以期促进该领域的进一步发展。 相似文献
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为了探讨热力学数据的精度对正庚烷燃烧模拟结果的影响,本文分别在B3LYP/6-31G(d,p)水平和G3水平上计算了正庚烷燃烧反应机理中物种的热力学数据,分别用这些数据模拟了正庚烷在不同条件下的绝热火焰温度和点火延时。同时对正庚烷燃烧反应的点火延时做了敏感度分析,探讨了对点火影响较大的物种。模拟结果表明:核心机理(C0-C4)的物种的热力学数据精度对正庚烷燃烧的模拟结果具有较大影响,而C4以上物种的热力学数据精度对结果影响不大。 相似文献
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合金纳米团簇作为一类新兴的多功能纳米材料已被广泛用于催化、光学传感以及生物医学成像等研究领域,而纳米团簇的可控合成和结构特征是调节纳米团簇性质并对其进一步利用的基础。尽管当前有关金属纳米团簇可控合成和结构特征的研究主要集中在单金属纳米团簇中,但有关合金纳米团簇原子精度的可控合成也取得了显著的进展。本文综述了配体保护的合金金属纳米团簇原子精度可控合成策略,包括一步合成法、金属交换、配体交换、化学刻蚀、簇间反应、原位两相配体交换以及最新的表面模体交换反应,并对相关合成策略的优缺点进行了详细的讨论和阐述。 相似文献
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Accurate weighing depends on both physical factors and the weighing technique. There are two categories of physical factors:
the location and support of the balance, and physical phenomena. Important such phenomena include processes of heat transfer
by convection and radiation in rarefriction gases, Archimedes buoyancy, electrostatic, magnetostatic and gravitational effects,
etc. Surveys of disturbances which affect the accuracy of weighing in vacuum or in controlled environments have been published
elsewhere. This paper describes a high-vacuum apparatus connected to a Cahn RG ultramicrobalance. The system was adapted for
investigations of long-time kinetic runs of oxygen loss in oxide superconductors in dynamic vacuum, and of other gas - solid
interactions. Typical calibration curves for 'not fully compensated system' are presented in controlled environments at cryogenic
temperatures.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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《Analytical letters》2012,45(12):2711-2727
Abstract The described alkali flame ionization detector (AFID) differs from other designs by introducing the alkali salt into the detector in the form of an aerosol. The preheated, desolvated alkali aerosol salt is introduced into a dual hydrogen gas flame assembly. This detector shows no evidence of fatigue due to the constant delivery of salt into the detector, compared to the fixed alkali supply found in other versions, which can be depleted by vaporization and become easily contaminated. This AFID design also allows for operation as an FID by implementing a simple pneumatic procedure. This paper deals with the performance and optimization of the detector using a dual alkali salt aerosol flame design for organonitrogen and organophosphorus compounds. Detection limits were 23.5 pgN/sec for alachlor, 185 pgN/sec for dinoseb, and 4.83 pgP/sec to 10.1 pgP/sec for various pesticides studied. Selectivity ratios are tunable to 6.6 × 106 gP/gC, 4.0 × 104 gN/gC and 2.3 × 103 gP/gN by establishing the appropriate detector gas flow rates. 相似文献
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The assessment of electronic balances for accuracy of mass measurements in the analytical laboratory
The accuracy of mass measurements when using electronic balances is considered within the frame of analytical assays in terms
of the uncertainty budget according to the internal quality control routine, the calibration process, the balance specifications,
and the weighing scenarios. Buoyancy corrections for both conventional and true mass are fully discussed. The procedure is
illustrated with a worked example. 相似文献
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Frank Scholze Burkhard Beckhoff Michael Kolbe Michael Krumrey Matthias Müller Gerhard Ulm 《Mikrochimica acta》2006,155(1-2):275-278
Energy-dispersive X-ray spectrometry offers the opportunity for a fast and reliable determination of the composition of a
specimen. For fundamental parameter based quantification, detailed knowledge of the X-ray generation cross sections and of
the detection system’s efficiency is required. The detection efficiency is determined comparing the measured and calculated
spectrum of undispersed synchrotron radiation (SR) from the electron storage ring BESSY II in the spectral range from 0.1 keV
to 100 keV. Alternatively, monochromatized SR in the spectral range from 0.1 keV to 60 keV is used to determine the detection
efficiency with a typical relative uncertainty of 1% to 2% by direct comparison with a reference detector. Employing well-calibrated
detectors and monochromatized SR of well-known radiant power and high spectral purity, fluorescence yields have been investigated
and resonant Raman scattering was studied as an example of a basic effect creating spectral background. 相似文献
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研制了一种适合普通厚度盖片的分析芯片的差示式非接触电导检测器。在芯片上制作分离通道和参比通道,并在独立的电极板上对应于两通道末端位置设置两对电极,分析芯片置于电极板上。信号发生器产生的高频信号分成两路,分别加至分离通道和参比通道对应的激发电极,两通道对应的接收电极的微弱信号经差示放大和整流。当组分经过分离通道电极间区域时,电导率与参比通道出现差异,获得检测信号。实验考察了激发频率、激发电压、电极间距等对检测性能的影响。在优化检测条件下,即检测频率100 kHz、检测电压10 V(Vp-p)、电极间距0.9 mm时,对K+的检出限达12μmol·L-1,相对标准偏差为1.1%,并成功用于Na+、K+离子的分离检测。该检测器适用于容易制作的普通厚度盖片的分析芯片的检测,且芯片与电极板相互独立,使用方便。 相似文献
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Peter J. Statham 《Mikrochimica acta》2006,155(1-2):289-294
Despite advances in electronic design, pile-up artefacts are still common in EDX spectra and can lead to false element identifications,
inaccurate correction for peak overlap and losses of counts that give poor quantitative results. With the capability to do
spectrum imaging there is increasing temptation to work at count rates far beyond the correction capability of pile-up inspection
electronics. Fundamental limitations due to noise are explained and a new correction procedure is described that implements
a comprehensive channel-by-channel correction for pile-up. Practical examples are given that demonstrate the range of application
of the new algorithm and show that, with correction, count rates at least 4 times higher can be used with no sacrifice in
performance. 相似文献