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Fast high-resolution nuclear magnetic resonance spectroscopy through indirect zero-quantum coherence detection in inhomogeneous fields 下载免费PDF全文
In many cases, high-resolution nuclear magnetic resonance (NMR) spectra are virtually impossible to obtain by con- ventional nuclear magnetic resonance methods because of inhomogeneity of magnetic field and inherent heterogeneity of sample. Although conventional intramolecular zero-quantum coherence (ZQC) can be used to obtain high-resolution spectrum in inhomogeneous field, the acquisition takes rather long time. In this paper, a spatially encoded intramolecular ZQC technique is proposed to fast acquire high-resolution NMR spectrum in inhomogeneous field. For the first time, the gradient-driven decoding technique is employed to selectively acquire intramolecular ZQC signals. Theoretical analyses and experimental observations demonstrate that high-resolution NMR spectral information can be retrieved within several scans even when the field inhomogeneity is severe enough to erase most spectral information. This work provides a new way to enhance the acquisition efficiency of high-resolution intramolecular ZQC spectroscopy in inhomogeneous fields. 相似文献
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This paper describes the fabrication and characteristics of the lateral Ti/4H-SiC Schottky barrier diodes (SBDs). SBDs are fabricated by nitrogen ion implantation into p-type 4H-SiC epitaxial layer. The implant depth profile is simulated using the Monte Carlo simulator TRIM. Measurements of the reverse I-V characteristics demonstrate a low reverse current, that is good enough for many SiC-based devices such as SiC metal-semiconductor field-effect transistors, and SiC static induction transistors. The parameters of the diodes are extracted from the forward I-V characteristics. The barrier height φ_b of Ti/4H-SiC is 0.95 eV. 相似文献
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红外波片相位延迟的测试方法及精度分析 总被引:8,自引:1,他引:7
通过全面分析光强随波片方位角的变化从中优化出可适用于红外波段的确定波片延迟的方法。此方法只需读取输出光强的最大值和最小值,通过简单运算得到所测波片的相位延迟。以此为理论基础,建立了一套红外波片检测系统,此系统使用元件的数量较少,操作简单,重复性好,易于得到较高的测试精度。此外,从系统光源、光学元件到接收器件等组成部分分析了整个系统中各种误差源对测试精度的影响。结果表明,该系统的检测精度与波片延迟有关,并给出其关系曲线,由该曲线可知,当所测波片的延迟大于40ο时,该系统的仪器相对误差在1%之内,对于常用1/4和1/2波片,仪器相对误差分别为0.2%和0.01%。该检测系统的测试精度在可见和近红外波段基本保持不变。 相似文献
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中国化学物相分析研究的新成就(上) 总被引:1,自引:0,他引:1
分两部分介绍了我国化学物相分析近十余年来研究的新成就。第一部分首先概述其前沿领域研究进展,继而对物料物质组成的相态与元素(Ag、Al、As、Au、B、Ba、Br、C、Ca、 Mg、Cd、Ce、Cl、Co、Ni、Cr、Cu、Pb和Zn等)价态分析的研究现状,分别予以简要评述。引用文献99篇。 相似文献
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建立了超高效液相色谱-四极杆/静电轨道阱高分辨质谱法检测动物源性产品中氟吡草酮及其代谢物残留量的方法。样品经甲酸-乙腈溶液提取,分散固相萃取净化,以甲醇-0.2%甲酸水溶液为流动相进行梯度洗脱分离,采用高分辨质谱平行反应监测扫描模式,以正离子模式进行定性定量分析,基质匹配外标法定量。结果表明,氟吡草酮在0.002~0.2μg/L范围、其代谢物SYN503780和代谢物CSCD686480在0.1~10μg/L范围线性关系良好,相关系数均大于0.995。空白样品在低、中、高3个加标水平下的平均回收率为84.5%~107.9%,相对标准偏差(RSD,n=6)为3.5%~8.6%;方法定量限为0.01~0.5μg/kg。该方法可应用于动物源性产品中氟吡草酮及其代谢物的快速检测。 相似文献