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排序方式: 共有1411条查询结果,搜索用时 31 毫秒
881.
金纳米簇是一种制备工艺简单、具有分子级尺寸和量子效应的新型发光材料,近年来在化学发光检测中得到了广泛应用,特别是较多应用于体外生物检测.本文综述了金纳米簇化学发光(含电化学发光)体系在体外生物检测中的应用进展.首先,阐释了金纳米簇的合成方法、结构、性质及其化学发光基本原理;其次,总结了国内外近年来基于该体系的体外生物检...  相似文献   
882.
Kangqiao Cheng 《中国物理 B》2022,31(6):67104-067104
Quantum critical phenomena in the quasi-one-dimensional limit remain an open issue. We report the uniaxial stress effect on the quasi-one-dimensional Kondo lattice CeCo$_2$Ga$_8$ by electric transport and AC heat capacity measurements. CeCo$_2$Ga$_8$ is speculated to sit in close vicinity but on the quantum-disordered side of a quantum critical point. Upon compressing the ${c}$ axis, parallel to the Ce-Ce chain, the onset of coherent Kondo effect is enhanced. In contrast, the electronic specific heat diverges more rapidly at low temperature when the intra-chain distance is elongated by compressions along ${a}$ or ${b}$ axis. These results suggest that a tensile intra-chain strain ($\varepsilon_c >0$) pushes CeCo$_2$Ga$_8$ closer to the quantum critical point, while a compressive intra-chain strain ($\varepsilon_c<0$) likely causes departure. Our work provides a rare paradigm of manipulation near a quantum critical point in a quasi-1D Kondo lattice by uniaxial stress, and paves the way for further investigations on the unique feature of quantum criticality in the quasi-1D limit.  相似文献   
883.
Qiu-Hao Zhu 《中国物理 B》2022,31(10):108102-108102
Highly anisotropic thermal conductive materials are of significance in thermal management applications. However, accurate determination of ultrathin composite thermal properties is a daunting task due to the tiny thermal conductance, severely hindering the further exploration of novel efficient thermal management materials, especially for size-confined environments. In this work, by utilizing a hybrid measuring method, we demonstrate an accurate determination of thermal properties for montmorillonite/reduced graphene oxide (MMT/rGO) composite film with a thickness range from 0.2 μ m to 2 μ m. The in-plane thermal conductivity measurement is realized by one-dimensional (1D) steady-state heat conduction approach while the cross-plane one is achieved via a modified 3ω method. As-measured thermal conductivity results are cross-checked with different methods and known materials, revealing the high measurement accuracy. A high anisotropic ratio of 60.5, independent of composite thickness, is observed in our measurements, further ensuring the negligible measurement error. Notably, our work develops an effective approach to the determination of ultrathin composite thermal conductivity, which may promote the development of ultrathin composites for potential thermal-related applications.  相似文献   
884.
以核糖异头羧酸制备为起始,以可见光/金属镍双重催化脱羧偶联反应为核心,与氰基水解反应相结合,开发了一条新的模块化合成路线,实现了一系列苄基保护烟酰胺碳核苷类似物的高效合成,其结构经1H NMR, 13C NMR和HR-MS( ESI)表征。   相似文献   
885.
陈晨  赵圣印  程少华 《合成化学》2013,21(3):342-344
以氰乙酸乙酯和原乙酸三甲酯为原料,经缩合反应制得2-氰基-3-甲氧基丁烯-2-羧酸乙酯(1);1与二甲基甲酰胺缩二甲醇缩合得2-氰基-5-(二甲氨基)-3-甲氧基-2,4-戊二烯酸乙酯(2);2在80%醋酸中环合得4-甲氧基-2-吡啶酮-3-甲酸乙酯(3);3在HBr中脱甲基和脱羧合成了4-羟基-2-吡啶酮,总收率31%,其结构经1H NMR,IR和MS确证。  相似文献   
886.
Three low-lying electronic states (X1∑, a3∑+, and A1II) of NO+ ion are studied using the complete active space self-consistent-field (CASSCF) method followed by highly accurate valence internally contracted multi-reference configuration interaction (MRCI) approach in combination of the correlation-consistent sextuple basis set augmented with diffuse functions, aug-cc-pV6Z. The potential energy curves (PECs) of the NO+(X1∑+, a3∑+, A1II) are calculated. Based on the PECs, the spectroscopic parameters Re, De, We, WeXe, ae, Be, and D0 are reproduced, which are in excellent agreement with the available measurements. By numerically solving the radial SchrSdinger equation of nuclear motion using the Numerov method, the first 20 vibrational levels, inertial rotation and centrifugal distortion constants of NO+(X1∑+, a3∑+, A1II) ion are derived when the rotational quantum number J is equal to zero (J = 0) for the first time, which accord well with the available measurements. Finally, the analytical potential energy functions of these states are fitted, which are used to accurately derive the first 20 classical turning points when J = 0. These results are compared in detail with those of previous investigations reported in the literature.  相似文献   
887.
A single-mode polymer optical fiber (POF) with highly photosensitive core doped with benzil dimethyl ketal (BDK) is fabricated and used for writing Bragg grating through the two-beam interference method. The Bragg wavelength of the grating is about 1570 nm, while the full-width at half-maximum (FWHM) of the reflection peak is 0.3 nm. The temperature response of POF Bragg grating is theoretically analyzed and experimentally measured in contrast to silica optical fiber Bragg grating (FBG). The result shows that the temperature character of POF Bragg grating is negative, which is opposite to the silica optical FBG. The absolute value of the temperature response of POF Bragg grating is one order of magnitude higher than that of the silica optical FBG, making POF Bragg grating appear to be very attractive for constructing temperature sensors with high resolution.  相似文献   
888.
DATB和TATB的特殊稳定性分析   总被引:1,自引:0,他引:1  
利用HONDO程序包,采用从头算法,计算了TNA、DATB和TATB的分子结构和分子内各原子上的净电荷.根据分子结构和各原子上的净电荷,深入分析了DATB和TATB的特殊稳定性.  相似文献   
889.
采用配体取代法 ,即在惰性气氛下以C60 取代Pt(CO) 2 (Pph3 ) 2 中的CO及Pph3 ,合成了C60 Pt(CO)(Pph3 )富勒烯金属配合物 ,利用元素分析、红外光谱、紫外可见光谱、光电子能谱等手段对产物进行鉴定和表征 ,结果表明 ,C60 以σ-π配位方式与Pt形成了稳定的 η2 型C60 配合物 .由于该分子存在超共轭作用 ,分子内电子流动性大 ,因而该配合物可能具有良好的光电转化性能及催化性能 .氧化还原性能研究表明 ,C60 在与金属有机基团Pt(CO) (Pph3 )形成配合物后 ,其还原电位向负方向发生了移动  相似文献   
890.
The melting curve of NaCI is studied up to 200 kbar by means of the shell-model molecular dynamics method, usiug massive shell core interaction potentials. The model for the interatomic interaction is shown to produce reasonable results at a wide range of pressures in bulk transitions. The pressure dependence of the melting curve of NaCl was calculated and the result was modified on the assumption of overheating due to the small system size and small time scale simulation. The final result is in good agreement with the corrected experimental values, accounting for melting mechanisms such as surface heating or superheating. Therefore, it is believed that bulk transition simulation at constant pressure indeed provides a useful tool for studying the melting transition.  相似文献   
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