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Theoretical Studies on the Hydrogen Bond Transfer and Proton Transfer between Anamorphoses of the Dihydrated Glycine Complex 被引量:3
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作者 WANG Ke-Cheng MENG Xiang-Jun SHI Jin LI Bing-Huan 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2007年第5期580-586,共7页
The conversion between anamorphoses of the dihydrated glycine complex was studied by means of B3LYP/6-31++G^**. It was found that proton transfer was accompanied by hydrogen bond transfer in the process of convers... The conversion between anamorphoses of the dihydrated glycine complex was studied by means of B3LYP/6-31++G^**. It was found that proton transfer was accompanied by hydrogen bond transfer in the process of conversion between different kinds of anamorphoses. With proton transfer, the electrostatic action was notably increased and the hydrogen-bonding action was evidently strengthened when the dihydrated neutral glycine complex converts into dihydrated zwitterionic glycine complex. The activation energy required for hydrogen bond transfer between dihydrated neutral glycine complexes is very low (6.32 kJ·mol^-1); however, the hydrogen bond transfer between dihydrated zwitterionic glycine complexes is rather difficult with the required activation energy of 13.52 kJ·mol^-1 due to the relatively strong electrostatic action. The activation energy required by proton transfer is at least 27.33 kJ·mol^-1, higher than that needed for hydrogen bond transfer. The activation energy for either hydrogen bond transfer or proton transfer is in the bond-energy scope of medium-strong hydrogen bond, so the four kinds of anamorphoses of the dihydrated glycine complex could convert mutually. 展开更多
关键词 intermolecular interaction B3LYP glycine hydrogen bond transfer proton transfer
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Density Functional Studies of the Reaction of Ytterbium Monocation with Fluoromethane:C-F Bond Activation and Electron-Transfer Reactivity
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作者 Dong Ju ZHANG Cheng Bu LIU 《Chinese Chemical Letters》 SCIE CAS CSCD 2002年第4期359-362,共4页
The potential energy surface and reaction mechanism corresponding to the reaction of ytterbium monocation with fluoromethane, which represents a prototype of the activation of C-F bond in fluorohydrocarbons by bare la... The potential energy surface and reaction mechanism corresponding to the reaction of ytterbium monocation with fluoromethane, which represents a prototype of the activation of C-F bond in fluorohydrocarbons by bare lanthanide cations, have been investigated for the first time by using density functional theory. A direct fluorine abstraction mechanism was revealed, and the related thermochemistry data were determined. The electron-transfer reactivity of the reaction was analyzed using the two-state model, and a strongly avoided crossing behavior on the transition state region was shown. The present results support the reaction mechanism inferred from early experimental data and the related thermochemistry data can provide a guide for further experimental researches. 展开更多
关键词 C-F bond activation electron transfer ytterbium monocation fluoromethane DFT
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DFT Calculations for Electron Transfer Bond-breakingReaction of CH_3-X
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作者 Yu Mei XING Zheng Yu ZHOU Ben Ni DU 《Chinese Chemical Letters》 SCIE CAS CSCD 2001年第4期347-350,共4页
DFT/6-311 + g** level calculations are performed tp study the electron transfer bond-breaking reaction of CH3-X. The calculated values are in good agreement with the experimental results or the empirical model. Throug... DFT/6-311 + g** level calculations are performed tp study the electron transfer bond-breaking reaction of CH3-X. The calculated values are in good agreement with the experimental results or the empirical model. Through analyzing the change of the energy and the charge densilty along hte reaction path, the bond-breaking in ET reaction for CH3X is investigated. 展开更多
关键词 electron transfer bond-breaking reaction density functional theory (DFT) CH_(3)X
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Spectroscopic Characterization, Molecular Modeling and DFT/TD-DFT/PCM Calculations of Novel Hydrogen-Bonded Charge Transfer Complex between Chloranilic Acid and 2-Amino-4,6-Dimethylpyridine
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作者 Khairia M. Al-Ahmary Fatimah A. Alshehri +1 位作者 Faten M. Atlam Mohamed K. Awad 《Open Journal of Physical Chemistry》 2020年第1期1-32,共32页
A charge transfer hydrogen bonded complex between the electron donor (proton acceptor) 2-amino-4,6-dimethylpyridine with the electron acceptor (proton donor) chloranilic acid has been synthesized and studied experimen... A charge transfer hydrogen bonded complex between the electron donor (proton acceptor) 2-amino-4,6-dimethylpyridine with the electron acceptor (proton donor) chloranilic acid has been synthesized and studied experimentally and theoretically. The stability constant recorded high values indicating the high stability of the formed complex. In chloroform, ethanol, methanol and acetonitrile were found the stoichiometric ratio 1:1. The solid complex was prepared and characterized by different spectroscopy techniques. FTIR, 1H and 13C NMR studies supported the presence of proton and charge transfers in the formed complex. Complemented with experimental results, molecular modelling using the density functional theory (DFT) calculations was carried out in the gas, chloroform and methanol phases where the existence of charge and hydrogen transfers. Finally, a good consistency between experimental and theoretical calculations was found confirming that the applied basis set is the suitable one for the system under investigation. 展开更多
关键词 2-Amino-4 6-Dimethylpyridine Charge transfer DFT Hydrogen bond Molecular Modelling COMPUTATIONS and Spectroscopy
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减税冲击、土地调控与城投债定价
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作者 罗美娟 黄子建 张牧扬 《西部论坛》 CSSCI 北大核心 2024年第5期65-79,共15页
减税冲击会加大地方财政压力,而地方政府隐性担保能力的下降会导致城投债发行利差上升;然而,城投债是地方经济建设的重要融资手段,地方政府有动机采取增信措施来抵消减税冲击的影响,甚至促使城投债利差下降。基于2017—2019年的三次增... 减税冲击会加大地方财政压力,而地方政府隐性担保能力的下降会导致城投债发行利差上升;然而,城投债是地方经济建设的重要融资手段,地方政府有动机采取增信措施来抵消减税冲击的影响,甚至促使城投债利差下降。基于2017—2019年的三次增值税税率下调实践,通过产业结构、减税点数和政策时间构造地级市层面的减税冲击变量,分析发现:减税冲击会扩大地方政府的财政收支缺口,但地方政府会采取土地调控措施来为城投公司提供增信,导致城投债的发行利差不升反降;具体而言,面对减税冲击,地方政府并没有调整土地出让结构、提高工业用地和住宅用地出让价格,而是通过向城投公司注入土地资产、提高商服用地出让价格的路径来提升城投公司的融资能力、抵押价值和信用水平,这也反映出地方政府“以地谋发展”的运作方式已由土地财政转向土地金融。因此,应深化土地要素市场化配置改革,打破地方政府在土地征收和出让环节的双垄断格局;划清地方投融资平台和地方政府之间的界限,促进地方财政的可持续发展,改变地方政府过度依赖土地调控的局面。 展开更多
关键词 增值税 城投债 信用利差 政府隐性担保 土地出让 土地资产 土地金融
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基于胶膜转印的气动微阀及微流控芯片
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作者 徐校杰 田浩为 +2 位作者 邱晔 吴梦希 刘军山 《微纳电子技术》 CAS 2024年第10期100-107,共8页
微阀是微流控芯片的重要部件,然而现有的微阀存在加工复杂、不利于批量生产等缺点,限制了微流控芯片的应用范围。研发了基于胶膜转印的胶粘键合方法,采用聚甲基丙烯酸甲酯(PMMA)微流道和聚二甲硅氧烷(PDMS)柔性薄膜制备了带有气动微阀... 微阀是微流控芯片的重要部件,然而现有的微阀存在加工复杂、不利于批量生产等缺点,限制了微流控芯片的应用范围。研发了基于胶膜转印的胶粘键合方法,采用聚甲基丙烯酸甲酯(PMMA)微流道和聚二甲硅氧烷(PDMS)柔性薄膜制备了带有气动微阀的微流控芯片。通过调节转印参数,在PDMS薄膜上可控地制备了厚度约为1μm胶膜,随后利用微米级的胶膜实现了PDMS薄膜与PMMA微流道层的胶粘键合,既避免了微流道的堵塞,又保证了微流道结构的精确性。设计并制备了由上层气体流道、中间柔性薄膜和下层液体流道构成的气动微阀,由上层气体流道内输入气压驱动PDMS薄膜向下层的液体流道变形以实现流体控制功能。构建了静力学模型分析微阀的关闭特性,根据薄膜变形的仿真结果优化微阀结构,确保微阀的有效截止。经测试,微阀具有优异的开关特性,关闭的响应时间为550ms,开启的响应时间为200ms。表征了不同气体和液体压强下的体积流量变化规律,验证了气动微阀可以实现对流体体积流量的精准调控。通过研发胶膜转印工艺实现了PMMA和PDMS的高效无损键合,开发了适合大规模制造的气动微阀,为微流控芯片进一步的实际应用开辟了新的途径。 展开更多
关键词 气动微阀 微流控芯片 聚甲基丙烯酸甲酯(PMMA) 胶粘键合 转印
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土地出让金划转税务部门征收对城投债的影响效应分析
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作者 吴多文 张雪莹 王倩 《证券市场导报》 CSSCI 北大核心 2024年第8期58-68,共11页
本文以土地出让金划转税务部门征收这一政策为切入点,考察其对城投债发行规模和信用风险的影响。实证结果显示,土地出让金划转税务部门征收政策实施后,城投债发行规模显著降低,但信用利差显著提升。在此基础上,本文探讨了土地出让金划... 本文以土地出让金划转税务部门征收这一政策为切入点,考察其对城投债发行规模和信用风险的影响。实证结果显示,土地出让金划转税务部门征收政策实施后,城投债发行规模显著降低,但信用利差显著提升。在此基础上,本文探讨了土地出让金划转税务部门征收对城投债信用风险的异质性影响、经济机制和风险化解渠道,结果显示:与东部地区相比,中部地区和西部地区的城投债信用利差显著提升,与所属较高行政级别地区的城投债相比,所属较低行政级别地区的城投债的信用利差显著提升;较高的土地依赖度、地方债务压力和企业偿债压力会加剧政策实施后城投债的信用风险;发行“借新还旧”城投债有助于缓解政策实施对城投债信用利差的正向效应。本文的研究为全面认识土地出让金征收改革的政策作用提供了事实依据,对防范化解城投债务风险提供了分析路径和参考。 展开更多
关键词 土地出让金 城投债 发行规模 信用利差
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晶圆键合设备对准和传送机构研究综述
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作者 吴尚贤 王成君 +1 位作者 王广来 杨道国 《电子与封装》 2024年第3期1-9,共9页
随着微机电系统和3D集成封装的快速发展,多功能高性能器件、小体积低功耗器件、耐高温耐高压器件以及小型化高集成度器件是目前封装领域研究的重点。晶圆键合设备对于这些高性能、多功能、小型化、耐高温、耐高压、低功耗的集成封装器... 随着微机电系统和3D集成封装的快速发展,多功能高性能器件、小体积低功耗器件、耐高温耐高压器件以及小型化高集成度器件是目前封装领域研究的重点。晶圆键合设备对于这些高性能、多功能、小型化、耐高温、耐高压、低功耗的集成封装器件的量产起着至关重要的作用,因此对晶圆键合设备及其对准机构和传送机构的研究也十分重要。介绍了常用的晶圆键合设备与晶圆键合工艺、对准机构和传送机构的工作原理以及主要的晶圆键合设备厂商现状,同时对晶圆键合设备对准和传送机构的发展趋势进行展望,其未来将朝着高精度、高对准速度、高吸附度和高可靠性的方向发展。 展开更多
关键词 晶圆键合 键合工艺 对准机构 传送机构
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面向深空探测任务的长寿命碳纳米管阴极研究
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作者 陈泽宣 肖东阳 +1 位作者 杜欢欢 宋培义 《深空探测学报(中英文)》 CSCD 北大核心 2024年第2期124-131,共8页
针对深空探测对长寿命碳纳米管场发射阴极的应用需求,从CNTs场发射阴极失效的机制分析出发,提出了长寿命CNTs场发射阴极的性能优化方案。采用图形化设计的CNTs发射簇结构可有效降低CNTs发射体表面的场强屏蔽效应,提升阴极的有效发射面积... 针对深空探测对长寿命碳纳米管场发射阴极的应用需求,从CNTs场发射阴极失效的机制分析出发,提出了长寿命CNTs场发射阴极的性能优化方案。采用图形化设计的CNTs发射簇结构可有效降低CNTs发射体表面的场强屏蔽效应,提升阴极的有效发射面积,避免电流集中于部分CNTs从而引起热量累积。提出一种转移键合工艺,将CNTs发射体与衬底的接触由分子力维持转变为金属层熔融键合,提高阴极的机械稳定性并降低了电/热阻抗。在高真空环境下对样机进行性能测试,优化后的CNTs场发射阴极样机实现了0~1 mA的电流范围、<2μA的电流分辨率与1μA/Hz^(1/2)@0.01~1 Hz的噪声水平,并通过了>550 h的连续发射试验,证明了阴极优化后的长周期稳定性。 展开更多
关键词 碳纳米管 场发射阴极 阵列化设计 边缘效应 转移键合工艺
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金纳米探针用于危化品过氧化氢的检测研究
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作者 顾小钰 邹宇鑫 +2 位作者 杨莉 赵楠楠 柴志华 《华北科技学院学报》 2024年第2期49-53,共5页
本文构建一种新型FRET纳米探针,用于H_(2)O_(2)的检测。首先通过紫外可见分光光度计、透射电镜及纳米粒度仪证实多糖功能化金纳米粒子的成功构建。接着利用荧光光谱仪证实荧光剂3-(丹磺酰氨)甲氧基苯硼酸成功组装到金纳米粒子的表面,形... 本文构建一种新型FRET纳米探针,用于H_(2)O_(2)的检测。首先通过紫外可见分光光度计、透射电镜及纳米粒度仪证实多糖功能化金纳米粒子的成功构建。接着利用荧光光谱仪证实荧光剂3-(丹磺酰氨)甲氧基苯硼酸成功组装到金纳米粒子的表面,形成简单可靠的FRET纳米探针。最后,利用荧光光谱仪证实,该纳米探针对H_(2)O_(2)的有效检测。 展开更多
关键词 金纳米粒子 葡聚糖 动态共价键 荧光共振能量转移 荧光淬灭
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The substituent effect on the excited state intramolecular proton transfer of 3-hydroxychromone
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作者 Yuzhi Song Songsong Liu +3 位作者 Jiajun Lu Hui Zhang Changzhe Zhang Jun Du 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第9期150-156,共7页
The excited state intramolecular proton transfer of four derivatives(FM, BFM, BFBC, CCM) of 3-hydroxychromone is investigated.The geometries of different substituents are optimized to study the substituent effects on ... The excited state intramolecular proton transfer of four derivatives(FM, BFM, BFBC, CCM) of 3-hydroxychromone is investigated.The geometries of different substituents are optimized to study the substituent effects on proton transfer.The mechanism of hydrogen bond enhancement is qualitatively elucidated by comparing the infrared spectra, the reduced density gradient, and the frontier molecular orbitals.The calculated electronic spectra are consistent with the experimental results.To quantify the proton transfer, the potential energy curves(PECs) of the four derivatives in S0 and S1 states are scanned.It is concluded that the ability of proton transfer follows the order: FM > BFM > BFBC > CCM. 展开更多
关键词 EXCITED state INTRAMOLECULAR PROTON transfer(ESIPT) hydrogen bond reduced density gradient(RDG) SUBSTITUENTS
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Catalytic transfer hydrogenolysis as an efficient route in cleavage of lignin and model compounds 被引量:6
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作者 Jiaguang Zhang 《Green Energy & Environment》 SCIE 2018年第4期328-334,共7页
Cleavage of aromatic ether bonds through hydrogenolysis is one of the most promising routes for depolymerisation and transformation of lignin into value-added chemicals. Instead of using pressurized hydrogen gas as hy... Cleavage of aromatic ether bonds through hydrogenolysis is one of the most promising routes for depolymerisation and transformation of lignin into value-added chemicals. Instead of using pressurized hydrogen gas as hydrogen source, some reductive organic molecules, such as methanol, ethanol, isopropanol as well as formates and formic acid, can serve as hydrogen donor is the process called catalytic transfer hydrogenolysis. This is an emerging and promising research field but there are very few reports. In this paper, a comprehensive review of the works is presented on catalytic transfer hydrogenolysis of lignin and lignin model compounds aiming to breakdown the aromatic ethers including a-O-4, b-O-4 and 4-O-5 linkages, with focus on reaction mechanisms. The works are organised regarding to different hydrogen donors used, to gain an in-depth understanding of the special role of various hydrogen donors in this process. Perspectives on current challenges and opportunities of future research to develop catalytic transfer hydrogenolysis as a competitive and unique strategy for lignin valorisation are also provided. 展开更多
关键词 CATALYTIC transfer HYDROGENOLYSIS Heterogeneous catalysis LIGNIN Hydrogen donor Aromatic ether bondS
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Thermodynamic Study and Spectroscopic Analysis of a Charge-Transfer Complex between 3,5-Diamino-1,2,4-Triazole and 6-Methyl-1,3,5-Triazine-2,4-Diamine with Chloranilic Acid
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作者 Khairia M. Al-Ahmary Ashwaq T. Alharbi 《Open Journal of Physical Chemistry》 2020年第1期33-47,共15页
Studying of charge-transfer (CT) and proton transfer interactions is essential due to their important role in many biological field and industrial applications. The current work will add more information’s about the ... Studying of charge-transfer (CT) and proton transfer interactions is essential due to their important role in many biological field and industrial applications. The current work will add more information’s about the nature of interaction between 3,5-diamino-1,2,4-triazole (DAT) and 6-methyl-1,3,5-triazine-2,4-diamine (MTDA) with 3,6-dichloro-2,5-dihydroxy-p-benzoquinone (chloranilic acid CLA) which was studied spectrophotometrically in Ethanol (EtOH) and Methanol (MeOH) solvents at different temperatures. The molecular composition of the formed complexes was studied by applying continuous variation and spectrophotometric titration methods and found to be 1:1 charge transfer complex for both Complex (DAT:CLA) and (MTDA:CLA) which are produced. Minimum-Maximum absorbance’s method has been applied to calculate the formation constant KCT and molecular extinction coefficient (ε);they recorded high values confirming high stability of the produced complexes. Oscillator strength (f), transition dipole moment (μ), ionization potential (IP) and dissociation energy (W) of the formed CT-complexes were also determined and evaluated;they showed solvent dependency. It is concluded that the formation constant (KCT) of the complexes is found to depend on the nature of both electron acceptor and donors and on the polarity of solvents. 展开更多
关键词 3 5-Diamino-1 2 4-Triazole 6-Methyl-1 5-Triazine-2 4-Diamine Charge transfer Hydrogen bond Spectroscopy
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控股股东股权质押、控制权转移与信用利差
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作者 周少甫 叶宁 《经济与管理》 CSSCI 2023年第4期61-71,共11页
利用中国A股上市公司2010—2021年银行间债券市场发行的债务融资工具数据探讨控股股东股权质押与信用利差之间的关系。研究结论表明,控股股东股权质押会导致公司发行债务融资工具信用利差更高。进一步研究发现,这一关系只存在于东部沿... 利用中国A股上市公司2010—2021年银行间债券市场发行的债务融资工具数据探讨控股股东股权质押与信用利差之间的关系。研究结论表明,控股股东股权质押会导致公司发行债务融资工具信用利差更高。进一步研究发现,这一关系只存在于东部沿海地区、个股股价崩盘风险较高和管理层能力较强的上市公司。通过对公司信息环境质量组和低掏空组的验证,排除了信息假说和掏空假说,验证了控制权转移风险假说的唯一性。 展开更多
关键词 股权质押 债务融资工具 银行间债券市场 控制权转移风险
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Pattern recognition and data mining software based on artificial neural networks applied to proton transfer in aqueous environments 被引量:2
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作者 Amani Tahat Jordi Marti +1 位作者 Ali Khwaldeh Kaher Tahat 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第4期410-421,共12页
In computational physics proton transfer phenomena could be viewed as pattern classification problems based on a set of input features allowing classification of the proton motion into two categories: transfer 'occu... In computational physics proton transfer phenomena could be viewed as pattern classification problems based on a set of input features allowing classification of the proton motion into two categories: transfer 'occurred' and transfer 'not occurred'. The goal of this paper is to evaluate the use of artificial neural networks in the classification of proton transfer events, based on the feed-forward back propagation neural network, used as a classifier to distinguish between the two transfer cases. In this paper, we use a new developed data mining and pattern recognition tool for automating, controlling, and drawing charts of the output data of an Empirical Valence Bond existing code. The study analyzes the need for pattern recognition in aqueous proton transfer processes and how the learning approach in error back propagation (multilayer perceptron algorithms) could be satisfactorily employed in the present case. We present a tool for pattern recognition and validate the code including a real physical case study. The results of applying the artificial neural networks methodology to crowd patterns based upon selected physical properties (e.g., temperature, density) show the abilities of the network to learn proton transfer patterns corresponding to properties of the aqueous environments, which is in turn proved to be fully compatible with previous proton transfer studies. 展开更多
关键词 pattern recognition proton transfer chart pattern data mining artificial neural network empiricalvalence bond
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晶体管级异质集成技术及其典型应用
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作者 陈堂胜 戴家赟 +5 位作者 吴立枢 孔月婵 周书同 齐志央 钟世昌 凌志健 《固体电子学研究与进展》 CAS 北大核心 2023年第2期95-100,共6页
晶体管级异质集成是后摩尔时代半导体微波器件技术发展的重点方向。介绍了针对平面和纵向两类不同结构器件分别开发的介质键合和金属键合两套外延层转移晶体管级异质集成工艺,研制出基于介质键合工艺的金刚石衬底GaN HEMT微波功率器件... 晶体管级异质集成是后摩尔时代半导体微波器件技术发展的重点方向。介绍了针对平面和纵向两类不同结构器件分别开发的介质键合和金属键合两套外延层转移晶体管级异质集成工艺,研制出基于介质键合工艺的金刚石衬底GaN HEMT微波功率器件和基于金属键合工艺的SiC衬底GaAs PIN限幅器电路。测试结果表明,与常规的SiC衬底GaN HEMT器件相比,金刚石衬底GaN HEMT器件在高热耗工作下器件热阻减小超过50%,连续波工作输出功率和功率附加效率分别提高0.77 dB和5.6个百分点;与常规工艺的GaAs衬底限幅器相比,18~40 GHz SiC衬底GaAs PIN限幅器单片电路限幅电平基本一致,插入损耗改善约0.2 dB,耐功率能力提高3 dB以上。 展开更多
关键词 半导体微波晶体管 晶体管级异质集成 外延层转移 低温键合 微波功率器件 限幅器
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基于外延层转移的超薄垂直结构深紫外LED 被引量:3
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作者 严嘉彬 孙志航 +2 位作者 房力 王林宁 王永进 《发光学报》 EI CAS CSCD 北大核心 2023年第2期321-327,共7页
AlGaN基深紫外(Deep ultraviolet,DUV)发光二极管(Light-emitting diode,LED)可用于杀菌、水体净化、光疗、固化、传感和非视距通信等场合,在生物、环境、工业、医疗和军事等领域具有广阔的应用前景。针对现阶段DUV LED外量子效率较低... AlGaN基深紫外(Deep ultraviolet,DUV)发光二极管(Light-emitting diode,LED)可用于杀菌、水体净化、光疗、固化、传感和非视距通信等场合,在生物、环境、工业、医疗和军事等领域具有广阔的应用前景。针对现阶段DUV LED外量子效率较低的问题,本文提出了一种超薄垂直结构的DUV LED方案。该方案基于蓝宝石-硅晶圆键合和物理减薄工艺实现了高质量DUV LED外延层从蓝宝石衬底到高导热硅基板的转移,并采用转移后亚微米厚度的超薄外延层制备出垂直结构的AlGaN DUV LED。器件的出光面在减薄工艺后无需特殊的化学处理便可实现纳米级的粗化,配合超薄外延层结构具备显著的失谐微腔效应,有助于破坏高阶波导模式,从而增加TM波的出光并提升器件的出光效率。测试表明,转移后的外延层厚度约为710 nm,制备出的DUV LED发光光谱峰值波长约为271 nm。该垂直结构DUV LED制备方案为实现高效DUV光源提供了可行路径。 展开更多
关键词 深紫外发光二极管 外延层转移 晶圆键合 减薄工艺
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铒掺杂氮氧化硅薄膜中不同敏化中心对铒离子光致和电致发光的影响
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作者 范宇轩 杨德仁 李东升 《材料科学与工程学报》 CAS CSCD 北大核心 2023年第4期527-531,共5页
研究了磁控溅射法制备的经不同温度热处理的掺铒氮氧化硅薄膜的光致发光和电致发光特性。实验发现光致发光中,提高热处理温度会促使硅纳米团簇的形成,它们的存在对薄膜中Er^(3+)离子的发光起到了敏化作用。在电致发光中,硅纳米团簇无法... 研究了磁控溅射法制备的经不同温度热处理的掺铒氮氧化硅薄膜的光致发光和电致发光特性。实验发现光致发光中,提高热处理温度会促使硅纳米团簇的形成,它们的存在对薄膜中Er^(3+)离子的发光起到了敏化作用。在电致发光中,硅纳米团簇无法成为载流子的捕获中心,敏化剂变为硅悬挂键,注入的电子和空穴可以在硅悬挂键引入的相关陷阱能级处复合,复合后的能量传递给铒离子后使其产生发光。 展开更多
关键词 掺铒氮氧化硅 硅纳米团簇 硅悬挂键 能量传递
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水团簇中协同拉伸振动引起的协同质子转移
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作者 李睿 王志刚 +1 位作者 王秀敏 施宇蕾 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2023年第S01期71-72,共2页
关于质子转移过程的起源有很多观点。在这项工作中,研究了光谱和核振动。发现水团簇的协同质子转移与O—H拉伸振动表现出极大的关联性。我们对循环水和棱柱水系统中的层内和层间氢键转移运动有了更好的理解。对称拉伸振动是协同氢交换... 关于质子转移过程的起源有很多观点。在这项工作中,研究了光谱和核振动。发现水团簇的协同质子转移与O—H拉伸振动表现出极大的关联性。我们对循环水和棱柱水系统中的层内和层间氢键转移运动有了更好的理解。对称拉伸振动是协同氢交换最相关的振动,本文对其进行了讨论。通过分析能垒,还研究了协同氢交换过程的质子动力学。在过渡态中,O—H键断裂和质子连接到相邻的O原子同时发生,并且不消耗共价键能量。进一步分析表明,相邻键之间存在很强的相关性,氢键沿氢键链的转移活动受氢键协同方式的影响较大。我们认为,这篇论文可能会对质子转移过程的起源产生重要的见解,并应激励未来的光谱和生物动力学研究。 展开更多
关键词 质子转移 氢键 水团簇 协同振动
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地方“发展型”政府财政压力与补充性融资选择 被引量:1
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作者 刘朝阳 李傲洋 张璐 《财贸研究》 CSSCI 北大核心 2023年第10期50-61,84,共13页
基于2009—2017年中国285个地级市的土地出让金和城投债数据,采用双向固定效应模型,实证检验“发展型”政府在财政压力作用下的补充性融资选择问题。研究发现:为缓解财政压力,地方“发展型”政府在融资选择上更偏向于土地出让金融资模式... 基于2009—2017年中国285个地级市的土地出让金和城投债数据,采用双向固定效应模型,实证检验“发展型”政府在财政压力作用下的补充性融资选择问题。研究发现:为缓解财政压力,地方“发展型”政府在融资选择上更偏向于土地出让金融资模式;土地出让金对城投债具有显著的“抵押增强”效应,即存在“以地撑债”的自我加强机制;源于“预期担保”效应,土地出让金对城投债违约风险的影响呈现“U”形变化。为破解中国地方政府对土地出让金的过度依赖和隐性债务风险积累的内生性,应加快完成三个转变,即政府职能从“发展型”转向“服务型”、政府投资从看“量”转向重“效”、政府融资从“行政干预”转向“市场”。 展开更多
关键词 地方“发展型”政府 财政压力 补充性融资 土地出让金 城投债
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