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991.
Abstract: Spectroscopy has been demonstrated to be an important method of analysis and detection. A spectral database system (SDBS) can not only satisfy the traditional requirements for spectral management but also provides several new functions, including spectra sharing on the website and web-based and real-time analysis and detection. Chemists and spectroscopists could analyze and detect pure materials and some mixtures rapidly with the help of standard SDBS, and now they are trying to improve these systems to fulfill rapid analysis for complex mixtures, even those as complex as agro-products. Overall, SDBS make it possible to analyze and detect unknown samples rapidly and nondestructively. This article focuses on significant progress in research on infrared (IR), near-infrared (NIR), and Raman SDBSs. Additionally, the drawbacks and obstacles of SDBSs are summarized and trends are discussed. 相似文献
992.
Guoxi Xie Xiang Feng Anthony G. Christodoulou Dehe Weng Xin Liu Bensheng Qiu 《Magnetic resonance imaging》2013
The partial separability (PS) of spatiotemporal signals has been exploited to accelerate dynamic cardiac MRI by sampling two datasets (training and imaging datasets) without breath-holding or ECG triggering. According to the theory of partially separable functions, the wider the range of spatial frequency components covered by the training dataset, the more accurate the temporal constraint imposed by the PS model. Therefore, it is necessary to develop a new sampling scheme for the PS model in order to cover a wider range of spatial frequency components. In this paper, we propose the use of radial sampling trajectories for collecting the training dataset and Cartesian sampling trajectories for collecting the imaging dataset. In vivo high resolution cardiac MRI experiments demonstrate that the proposed data sampling scheme can significantly improve the image quality. The image quality using the PS model with the proposed sampling scheme is comparable to that of a commercial method using retrospective cardiac gating and breath-holding. The success of this study demonstrates great potential for high-quality, high resolution dynamic cardiac MRI without ECG gating or breath-holding through use of the PS model and the novel data sampling scheme. 相似文献
993.
Ming‐Zheng Wang Feng‐Xia Liang Biao Nie Long‐Hui Zeng Ling‐Xia Zheng Peng Lv Yong‐Qiang Yu Chao Xie Yang Yang Li Lin‐Bao Luo 《Particle & Particle Systems Characterization》2013,30(7):630-636
Schottky junctions made from a titanium dioxide nanotube (TiO2NT) array in contact with a monolayer graphene (MLG) film are fabricated and utilized for UV light detection. The TiO2NT array is synthesized by the anodization and the MLG through a simple chemical vapor deposition process. Photoconductive analysis shows that the fabricated Schottky junction photodetector (PD) is sensitive to UV light illumination with good stability and reproducibility. The corresponding responsivity (R), photoconductive gain (G), and detectivity (D*) are calculated to be 15 A W?1, 51, and 1.5 × 1012 cm Hz1/2 W?1, respectively. It is observed that the fabricated PD exhibits spectral sensitivity and a simple power‐law dependence on light intensity. Moreover, the height of the Schottky junction diode is derived to be 0.59 V by using a low temperature I–V measurement. Finally, the working mechanism of the TiO2NT array/MLG film Schottky junction PD is elucidated. 相似文献
994.
Li1.1Mn2???2x Co x Ni x O4 (x?=?0, 0.075) spinel powders were successfully synthesized using a liquid stirred tank reactor method. The electrochemical performances of the undoped and doped spinels at 4.3 and 5 V were investigated by X-ray diffraction, field-emission scanning electron microscopy, and electrochemical impedance spectroscopy. The capacity of Li1.1Mn2???2x Co x Ni x O4 could be divided into two parts, with 4.3 V as the dividing line in the 3–5 V charge–discharge range. Low capacity and good cyclic performance were obtained when cycled in the 3–4.3 V range for the multi-doped Li1.1Mn2???2x Co x Ni x O4 spinel. In comparison with multi-doped spinel at 4.3 V, the results of the cyclic performance worsened at 5 V because the structure underwent further shrinkage, the charge transfer resistance rose and the electrolyte decomposed. 相似文献
995.
Feng Deng Lizhi Xiao Huabing Liu Tianlin An Mengying Wang Zongfu Zhang Wei Xu Jiajie Cheng Qingming Xie Vladimir Anferov 《Applied magnetic resonance》2013,44(9):1053-1065
Nuclear magnetic resonance (NMR) under motion has drawn significant attention in recent years. Motion of the NMR probe has serious effects on NMR measurement. For example, NMR logging normally runs at downhole condition with tool motion at a speed of 30 ft/min. We propose here methods for motion corrections of NMR data based on the quantitative analysis of motion effects on polarization and echo acquisition. We also produced a multi-functional NMR scanning system to verify the theoretical analysis. Presented experiments demonstrate that the theoretical and experimental results match very well. 相似文献
996.
A sensitive hydroxylamine sensor is developed by electrodeposition of Pt nanoparticles on pre-synthesized polypyrrole nanoparticles modified glassy carbon electrode. The modified electrode presents distinctly electrocatalytic activity toward hydroxylamine oxidation. The kinetic parameters such as the overall numbers of electrons involved in hydroxylamine oxidation, the electron transfer coefficient, standard heterogeneous rate constant, and diffusion coefficient are evaluated. The current response increases linearly with increasing hydroxylamine concentrations and exhibits two wide linear ranges of 5.0?×?10?7–1.1?×?10?3 and 1.1?×?10?3–18.8?×?10?3 M with a detection limit of 0.08 μM (s/n?=?3). The proposed electrode presents excellent operational and storage ability for determining hydroxylamine. Moreover, the sensor shows good sensitivity, selectivity, and reproducibility properties. 相似文献
997.
利用高分辨率X射线衍射(HRXRD)对MOCVD系统中生长在c面Al2O3上的不 同厚度的GaN薄膜内马赛克结构进行了研究. 在对称面的三轴X射线衍射曲线中, 用两种方法计算得到晶粒的垂直关联长度和水平关联长度, 两者均随着薄膜厚度的增加而增加, 并且垂直关联长度近似膜厚从倒易空间图中得出的横向关联长度也有相同的趋势, 结合非对称面的衍射曲线用Williamson-Hall方法和外推法分 别拟合出晶粒的面外倾斜角和面内扭转角, 他们随着薄膜厚度的增加显著减少, 这一切都表明厚度的增加, 晶粒的单向有序排列越来越整齐, 外延片的质量越来越高.
关键词:
GaN薄膜马赛克结构
厚度
HRXRD 相似文献
998.
柔性有机场效应晶体管具有可折叠、质量轻、低成本等优点,在柔性显示、柔性传感器、柔性射频标签和柔性集成电路等方面显示了广阔的应用前景.本文在介绍柔性有机场效应 晶体管最新研究进展的基础上, 总结了柔性有机场效应晶体管的器件结构和柔性有机场效应晶体管所使用的衬底材料、 栅绝缘层材料、有源层材料及电极材料, 阐述了柔性有机场效应晶体管的制备工艺, 并讨论了不同的弯曲方式对柔性有机场效应晶体管性能的影响, 最后总结和展望了柔性有机场效应晶体管的应用领域.
关键词:
柔性
晶体管
有机/聚合物
溶液加工 相似文献
999.
本文研究了不同磁场环境下一维Heisenberg XXZ自旋链中两量子比特的热量子失协特性. 在四种不同的磁场环境下: 1) B1=B2=0 (无磁场); 2) B1≠0, B2=0 (磁场只作用于其中一个量子比特); 3) B1=B2 (均匀磁场); 4) B1=-B2 (非均匀磁场), 对分别作用在每个量子比特上的磁场B1和B2对其量子关联的影响作了详细的讨论, 且数值计算和比较了其量子失协和量子纠缠的异同. 结果显示: 在有限温度下, 量子失协相比于量子纠缠更普遍, 且非均匀磁场相比于均匀磁场对量子失协和量子纠缠更有用, 更有利于量子通讯和量子信息处理过程.
关键词:
量子关联
纠缠
量子失协 相似文献
1000.
基于密度泛函理论, 分别计算了α, γ铀的晶格常数、平衡态体积、体弹模量及其导数等, 与实验和其他第一性原理计算结果符合较好; 并根据焓-压强曲线得到了两相的相变压强~111GPa. 通过体心立方结构理想拉伸强度的计算, 分析其在极端加载条件下的结构行为. 另外, 计算了小应变情况下U-Nb (6.25at.%) 的能量-应变关系, 发现对应于剪切模量c’的应变会使得该结构的能量降低, 揭示了该结构的力学不稳定性.
关键词:
铀
相变
理想强度
结构稳定性 相似文献