检索结果-南通市图书馆

Theoretical analysis of the sound absorption characteristics of periodically stiffened micro-perforated plates

Acta Mechanica Sinica 2014年第5期30卷 714-726页

作者： Hai-An Zhou Xiao-Ming Wang yu-lin mei School of Mechanical Engineering Shandong University of Technology School of Mechanical Engineering Dalian University of Technology School of Automotive Engineering Dalian University of Technology

The vibro-acoustic responses and sound absorption characteristics of two kinds of periodically stiffened micro-perforated plates are analyzed theoretically. The connected periodical structures of the stiffened plates can be ribs or block-like structures. Based on fundamental acoustic formulas of the micro-perforated plate of Maa and Takahashi, semi-analytical models of the vibrating stiffened plates are developed in this paper. Approaches like the space harmonic method, Fourier transforms and finite element method （FEM） are adopted to investigate both kinds of the stiffened plates. In the present work, the vibro-acoustic responses of micro-perforated stiffened plates in the wavenumber space are expressed as functions of plate displacement amplitudes. After approximate numerical solutions of the amplitudes, the vibration equations and sound absorption coefficients of the two kinds of stiffened plates in the physical space are then derived by employing the Fourier inverse transform. In numerical examples, the effects of some physical parameters, such as the perforation ratio, incident angles and periodical distances etc., on the sound absorption performance are examined. The proposed approaches are also validated by comparing the present results with solutions of Takahashi and previous studies of stiffened plates. Numerical results indicate that the flexural vibration of the plate has a signif- icant effect on the sound absorption coefficient in the water but has little influence in the air.

关键词： Absorption- Stiffened- Micro-perforated Spaceharmonic - Finite element method

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

CCR7/p-ERK1/2/VEGF signaling promotes retinal neovascularization in a mouse model of oxygen-induced retinopathy

引用

International Journal of Ophthalmology(English edition) 2017年第6期10卷 862-869页

作者： lin-Hui yuan Xiao-Long Chen yu Di mei-lin Liu Department of Ophthalmology Shengjing Affiliated Hospital of China Medical University Shenyang 110000 Liaoning Province China

AIM： To investigate the role of CCR7/p-ERKI/2/VEGF signaling in the mouse model of oxygen-induced retinopathy （OIR）. METHODS： Neonatal C57BL/6J mice were evenly randomized into four groups： normoxia, OIR, OIR control （treated with scramble siRNA）, and OIR treated （treated with CCR7 siRNA）. Normoxia group was not specially handled. Postnatal day 7 （P7） mice in the OIR group were exposed to 75%±5% oxygen for 5d （P7-P12） and then maintained under normoxic conditions for 5d （P12-P17）. Mice in the OIR control and OIR treated groups were given injections of scramble or CCR7 siRNA plasmid on P12 before returning to normoxic conditions for 5d （P12-P17）. Retina samples were collected from all mice on P17, stained with adenosine diphosphatase （ADPase）, and retinal neovascularization （RNV） was assessed. Retinas were also stained with hematoxylin and eosin （H＆E） for RNV quantitation. The distribution and expression of CCR7, p-ERKI/2 and vas- cular endothelial growth factor （VEGF） were assessed via immunohistochemistry, Western blot, and quantitative real-time polymerase chain reaction （qRT-PCR）. RESULTS： High oxygen promoted retinal neovascularization （P〈0.05） and increased the number of endothelial nuclei in new vessels extending from the retina to the vitreous body; CCR7 promoted this process （P〈0.05）. CCR7 and VEGF mRNA were expressed at higher levels in the OIR and OIR control groups than in the normoxia and OIR treated groups. CCR7, p-ERK1/2, and VEGF protein were expressed in the retinas of mice in the OIR and OIR control groups. Intravitreal injection of CCR7 siRNA significantly reduced CCR7, p-ERKI/2, and VEGF expression in the OIR mouse model （all P〈0.05）. CCR7 significantly enhancedthe neovascularization and non-perfusion areas in the OIR group （P〈0,05）, CCR7 siRNA significantly reduced levels of p-ERK1/2 and VEGF as compared to OIR controls （P〈0.05）. CONCLUSION： These results suggest that CCR7/p-ERK I/2NEGF signaling plays an important role in OIR, CCR7 may be a p

关键词： chemokine receptor type 7 vascularendothelial growth factor extracellular signal-regulated kinase retinal neovascularization retinopathy ofpremamrity

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Metallacycle Expansion and Annulation:Access to Tetrazolo-Fused Osmacycles by Reaction of Cyclic Osmium Carbyne with Sodium Azide

引用

Chinese Journal of Chemistry 2021年第12期39卷 3435-3442页

作者： Hongjian Wang yu-mei lin Siyuan Chen Yonghong Ruan Haiping Xia State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China Shenzhen Grubbs Institute Department of ChemistrySouthern University of Science and TechnologyShenzhenGuangdong 518055China

The reaction of a cyclic osmacarbyne complex with sodium azide led to the formation of a ring expansion-annulation product,a unique tetrazole annulated polycyclic *** reaction proceeds by insertion of a nitrogen atom into the metal carbon triple bond and the second azide participating in the[2+3]*** successful isolation and characterization of metalla-azirine complex and metallapyridinium derivative strongly validated the mechanism for the formation of the title *** work demonstrates a new strategy to enrich the varieties of aza-metallacyclic species.

关键词： Metallacycles Osmiurncarbyne Ring expansion Annulation Aza-heterocycle

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Recent Advances in Asymmetric Transformations of Unactivated Alkanes and Cycloalkanes through Direct C—H Functionalization

引用

Chinese Journal of Chemistry 2022年第23期40卷 2825-2837,I0002页

作者： Shiyan Cheng Qianyu Li Xiuliang Cheng yu-mei lin Lei Gong Key Laboratoryof Chemical Biology of Fujian Province Collegeof Chemistry and Chemical EngineeringXiamen UniversityXiamen Fujian 361005China Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(IKKEM) XiamenFujian 361005China

The direct conversion of unactivated alkanes and cycloalkanes into structurally diverse molecules through aliphatic C—H functionalization is a useful process, which has attracted intense interest from academia and industry. Methods to control chemo- and site-selectivity, combined with asymmetric catalysis, provide appealing access to high value-added enantiomer-enriched compounds but are far less developed. This review focuses on recent progress in (i) asymmetric reactions of alkanes or cycloalkanes with prochiral substrates which generate a stereocenter adjacent to the cleaved C(sp3)–H bond, and (ii) C(sp3)–H enantiodiscriminatory reactions creating a new stereogenic center on the carbon of a cleaved C(sp3)–H bond. Elegant strategies are discussed, including (a) metal carbene-induced C—H insertions by chiral rhodium catalysts, (b) metal-oxo-mediated C—H oxidation by biomimetic manganese catalysts, (c) enzyme catalysis by cytochromes P450 variants, and (d) dual catalysis by a photocatalyst and a chiral Lewis acid (CLA) or a chiral phosphoric acid (CPA). These catalytic systems can not only precisely recognize primary, secondary and tertiary C—H bonds at specific positions in alkanes and cycloalkanes, but also support a high level of stereoselectivity in the reactions. It is expected that the advances will stimulate further progress in asymmetric catalysis, synthetic methodology, pharmaceutical development and industrial processes.

关键词： Asymmetric catalysis C-H functionalization Alkane Site-selectivity Enantioselectivity

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Transparent conductive SnO_(2)thin films via resonant Ta doping

引用

Science China Materials 2023年第1期66卷 264-271页

作者： Vedaste Uwihoreye Zhenni Yang Jia-Ye Zhang yu-mei lin Xuan Liang Lu Yang Kelvin H.L.Zhang College of Chemistry and Chemical Engineering Xiamen UniversityXiamen 361005China

Transparent conductive oxide(TCO)thin films are highly desired as electrodes for modern flat-panel displays and solar *** indium-free TCO materials are highly needed,because of the scarcity and the high price of *** on the mechanism of resonant doping,Ta has been identified as an effective dopant for SnO_(2)to achieve highly conductive and transparent *** this work,we fabricated a series of Ta-doped SnO_(2)thin films(Sn_(1-x)Ta_(x)O_(2),x=0.001,0.01,0.02,0.03)with high conductivity and high optical transparency via a low-cost sol-gel spin coating *** Sn_(0.98)Ta_(0.02)O_(2)film achieves the highest electrical conductivity of 855 S cm-1with a carrier concentration of2.3×10^(20)cm^(-3)and high mobility of 23 cm^(2)V^(-1)s^(-1).The films exhibit a very high optical transparency of 89.5%in the visible light ***-resolution X-ray photoemission spectroscopy and optical spectroscopy were combined to gain insights into the electronic structure of the Sn_(1-x)Ta_(x)O_(2)*** optical bandgaps of the films are increased from 3.96 eV for the undoped SnO_(2)to 4.24 eV for the Sn_(0.98)Ta_(0.02)O_(2)film due to the occupation of the bottom of conduction band by free electrons,i.e.,the Burstein-Moss ***,a bandgap shrinkage is also directly observed due to the bandgap renormalization arising from many-body *** double guarantee of transparency and conductivity in Sn_(1-x)Ta_(x)O_(2)films and the low-cost growth method provide a new platform for optoelectronic and solar cell applications.

关键词： transparent conductive oxide sol-gel spin coating Ta-doped SnO_(2) electronic structure

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Direct Z-scheme WO_(3-x) nanowire-bridged TiO_(2) nanorod arrays for highly efficient photoelectrochemical overall water splitting

引用

Journal of Energy Chemistry 2021年第8期30卷 721-729,I0015页

作者： Sheng lin He Ren Zhi Wu Lan Sun Xia-Guang Zhang yu-mei lin Kelvin H.L.Zhang Chang-Jian lin Zhong-Qun Tian Jian-Feng Li State Key Laboratory of Physical Chemistry of Solid Surfaces Department of ChemistryCollege of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China Shenzhen Research Institute of Xiamen University Shenzhen 518000China Key Laboratory of Green Chemical Media and Reactions Ministry of EducationCollaborative Innovation Center of Henan Province for Green Manufacturing of Fine ChemicalsSchool of Chemistry and Chemical EngineeringHenan Normal UniversityXinxiang 453007China

All-solid-state Z-scheme photocatalysts for overall water splitting to evolve H_(2) is a promising strategy for efficient conversion of solar ***,most of these strategies require redox ***,a direct Z-scheme photoelectrocatalytic electrode based on a WO_(3-x)nanowire-bridged TiO_(2)nanorod array heterojunction is constructed for overall water splitting,producing H_(2).The as-prepared WO_(3-x)/TiO_(2)nanorod array heterojunction shows photoelectrochemical(PEC)overall water splitting activity evolving both H_(2) and O_(2)under UV-vis light *** optimum PEC activity was achieved over a 1.67-WO_(3-x)/TiO_(2)photoelectrode yielding maximum H_(2) and O_(2)evolution rates roughly 11 times higher than that of pure TiO_(2)nanorods without any sacrificial agent or redox *** role of oxygen vacancy in WO_(3-x)in affecting the H_(2) production rate was also comprehensively *** superior PEC activity of the WO_(3-x)/TiO_(2)electrode for overall water splitting can be ascribed to an efficient Z-scheme charge transfer pathway between the WO_(3-x)nanowires and TiO_(2)nanorods,the presence of oxygen vacancies in WO_(3-x),and a bias potential applied on the photoelectrode,resulting in effective spatial charge *** study provides a novel strategy for developing highly efficient PECs for overall water splitting.

关键词： TiO_(2) nanorod arrays WO_(3-x) nanowire Heterostructure Photoelectrochemical Hydrogen production

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Alternation of Metal-Bridged Metallacycle Skeletons:From Ruthena- pentalyne to Ruthenapentalene and Ruthenaindene Derivative

引用

Chinese Journal of Chemistry 2018年第12期36卷 1156-1160页

作者： Jinhua Li Huijun Kang Kaiyue Zhuo qingde Zhuo Hong Zhang yu-mei lin Haiping Xia Department of Chemistry College of Chemistry and Chemical EngineeringXiamen UniversityXiamenFujian 362005China

The reaction of ruthenapentalyne with one equivalent of isocyanide led to the formation of a rare ruthenapentalene complex by nucleophilic addition. When excess isocyanides were used, the metal‐bridged ruthenaindene derivatives can be isolated and were formed by one carbon of isocyanide insertion into the ruthenacycle. Complexes 3 represent the first metallaindene derivatives with a second‐row transition metal at the bridge‐head position. The transformations from ruthenapentalyne via ruthenapentalene to ruthenaindene derivatives are of interest and can be extended to the syntheses of other polycyclic ruthenacycles. These unique metallacycles exhibit considerable stability and broad spectral absorption spanning the visible spectrum, enabling their potential applications in photoelectric materials.

关键词： metallacycle ruthenium indene isocyanide ring‐expansion

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Transition metal-free photocatalytic reductive deuteration of ketone derivatives

引用

Green Synthesis and Catalysis 2023年第3期4卷 253-257页

作者： Jiaxin Cai Yanjun Li Ziqi Ye Wenqian Wang yu mei lin Lei Gong Key Laboratory of Chemical Biology of Fujian Province College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(IKKEM) Xiamen 361005China

Deuterium labelling techniques have shown widespread applications in organic synthesis,analytic chemistry,life science and material *** design of practical deuteration reactions which is environmentally friendly is highly desired for pharmaceutical development and industrial processes while remaining *** herein report a convenient,transition metal-free strategy for reductive deuteration of ketone derivatives toα-deuterated alcohols by employing a conjugated aryl amine-based organophotocatalyst,a dipropyl disulfide cocatalyst and an inorganic *** irradiation with visible light and under an air atmosphere,a variety of diaryl ketones,heteroaryl ketones,cyclic ketones,α-ketoesters,benzil derivatives,aliphatic ketones and drug-like molecules were converted into correspondingα-deuterated aryl alcohols in good to excellent yields and with high deuterium incorporation(up to 99%D-incorporation).Only low toxic side-products,such as sodium salts and carbon dioxide,were ***,the synthetic utility of this method is highlighted by the preparation of several D-labeled drug-like molecules,including orphenadrine,carbinoxamine and modafinil.

关键词： Deuteration Photoredox Organocatalysis Visible light α-Deuterated alcohols

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nickel-Catalyzed Regiodivergent Asymmetric Cycloadditions of α,β-Unsaturated Carbonyl Compounds

引用

CCS Chemistry 2022年第9期4卷 3122-3133页

作者： Shi Cao Ziqi Ye yuehua Chen yu-mei lin Jiahua Fang yuejiao Wang Boxuan Yang Lei Gong Key Laboratory of Chemical Biology of Fujian Province iChEMCollege of Chemistry and Chemical EngineeringXiamen UniversityXiamenFujian 361005

Regiodivergent asymmetric cycloadditions from the same set of starting materials offer interesting opportunities for rapid construction of optically active cyclic molecules with structural ***,this remains a challenging task due to the difficulty of simultaneously controlling the regio-,diastereo-,and enantioselectivity in the ring formation *** address this long-standing problem.

关键词： cycloaddition regiodivergent asymmetric photocatalysis visible light nickel

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

福建省农村新村建设模式和发展思路

引用

福建师范大学学报（哲学社会科学版） 2006年第6期 42-47页

作者：林玉妹上海对外贸易学院社科部上海201600

本文在对福建省部分地区实地调研的基础上,分析了20世纪90年代后期以来福建省农村新村建设取得的成效和存在的问题,认为进一步推进农村新村建设,必须把握好农村新村建设的基本条件,通过典型示范,分层次推进。

关键词：新村建设农村经济建设模式

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：