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991.
Real-time detection of electron tunnelling in a quantum dot 总被引:3,自引:0,他引:3
Nanostructures in which strong (Coulomb) interactions exist between electrons are predicted to exhibit temporal electronic correlations. Although there is ample experimental evidence that such correlations exist, electron dynamics in engineered nanostructures have been observed directly only on long timescales. The faster dynamics associated with electrical currents or charge fluctuations are usually inferred from direct (or quasi-direct) current measurements. Recently, interest in electron dynamics has risen, in part owing to the realization that additional information about electronic interactions can be found in the shot noise or higher statistical moments of a direct current. Furthermore, interest in quantum computation has stimulated investigation of quantum bit (qubit) readout techniques, which for many condensed-matter systems ultimately reduces to single-shot measurements of individual electronic charges. Here we report real-time observation of individual electron tunnelling events in a quantum dot using an integrated radio-frequency single-electron transistor. We use electron counting to measure directly the quantum dot's tunnelling rate and the occupational probabilities of its charge state. Our results provide evidence in favour of long (10 micros or more) inelastic scattering times in nearly isolated dots. 相似文献
992.
罗源湾及九龙江口美肩鳃鳚仔、稚鱼的新记录 总被引:1,自引:0,他引:1
研究了罗源湾和九龙江口美肩锶鲥仔、稚鱼的形态特征,时空分布及其与环境的关系,美肩锶鲥不仅分布在黄海和渤海,南海和东海也有分布。仔稚鱼的主要特征:眼大、吻短、稍突出、头高、体中等延长,左右侧肩,头顶包一骨质冠,头冠左右两侧及左右眼眶上有骨嵴,前锶盖骨隅角具一强棘,以上构造都着生小刺,前鳃盖骨后缘有4枚小棘突,腹囊大,背面具黑色素点,肌节37~45(8-12 28-32),背鳍一个,延长,胸鳍大,腹鳍喉位,背、臀鳍的两支鳍骨之间有尖三角形骨片。 相似文献
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996.
相关数字经济的研究大多聚焦于理论性、经验性、范例式,较少涉及数字经济影响因素的定量研究。本研究结合《国民经济行业分类》和《所有经济活动的国际标准行业分类》中关于数字经济部门类别的界定,提出数字经济的定义,分析数字经济发展路径与驱动机制,提炼出可能的影响因素,从OECD、世界银行、瑞士洛桑管理学院的数据库中筛选出96条数据,对比前进法、后退法、逐步回归法的回归结果得到基础模型,最终得到的回归方程包含7个均具有显著作用的变量,实证分析了数字经济的影响因素,以期为各地选择数字经济发展模式、路径提供借鉴。 相似文献
997.
Review of the fabrication and application of porous materials from silicon-rich industrial solid waste 下载免费PDF全文
Chao Miao Lixing Liang Fan Zhang Shumei Chen Kaixuan Shang Jinlong Jiang Yi Zhang Jing Ouyang 《矿物冶金与材料学报》2022,29(3):424-438
Porous materials have promise as sound insulation, heat barrier, vibration attenuation, and catalysts. Most industrial solid wastes, such as tailings, coal gangue, and fly ash are rich in silicon. Additionally, a high silicon content waste is a potential raw material for the syn- thesis of silicon-based, multi-porous materials such as zeolites, mesoporous silica, glass-ceramics, and geopolymer foams. Representative sil- icon-rich industrial solid wastes (SRISWs) are the focus of this mini review of the processing and application of porous silicon materials with respect to the physical and chemical properties of the SRISW. The transformation methods of preparing porous materials from SRISWs are summarized, and their research status in micro-, meso-, and macro-scale porous materials are described. Possible problems in the application of SRISWs and in the preparation of functional porous materials are analyzed, and their development prospects are discussed. This review should provide a typical reference for the recycling and use of industrial solid wastes to develop sustainable “green materials.” 相似文献
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Copper matrix composites reinforced by in situ-formed hybrid titanium boride whiskers (TiBw) and titanium diboride particles (TiB2p) were fabricated by powder metallurgy. Microstructural observations showed competitive precipitation behavior between TiBw and TiB2p, where the relative contents of the two reinforcements varied with sintering temperature. Based on thermodynamic and kinetic assessments, the precipitation mechanisms of the hybrid reinforcements were discussed, and the formation of both TiBw and TiB2p from the local melting zone was thermodynamically favored. The precipitation kinetics were mainly controlled by a solid-state diffusion of B atoms. By forming a compact compound layer, in situ reactions were divided into two stages, where Zener growth and Dybkov growth prevailed, respectively. Accordingly, the competitive precipitation behavior was attributed to the transition of the growth model during the reaction process. 相似文献
1000.