检索结果-南通市图书馆

The influence of temperature on the PLC effect in Al-Mg alloy

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

Science China(Technological Sciences) 2011年第6期54卷 1389-1393页

作者： FU Shihua ZHANG qingChuan hu qi GONG Ming CAO PengTao LIU HaoWen CAS Key Laboratory of Mechanical Behavior and Design of Materials University of Science and Technology of China Hefei 230037 China

An experimental investigation of the influence of temperature on the Portevin-Le Chatelier(PLC) effect in Al-Mg alloy is *** a certain strain rate,the PLC effect is present in the temperature range of 223-328 *** serration amplitude increases monotonically with increasing temperature,whereas the behaviors of the serration period and the critical strain with temperature include a descending branch under corresponding low temperature range and an ascending branch under corresponding high temperature *** analysis in relation with dynamic strain aging(DSA) indicates that the temperature plays an important role in the PLC effect by dictating the solubility and the diffusibility of solute *** the concentration and the diffusibility of solute atoms contribute to increasing the serration *** the descending branch temperature range,the serration period mainly depends on the preparation phase and the dominant factor of critical strain is the velocity of ***,under the ascending branch temperature range,the serration period mainly depends on the pinning phase and the dominant factor of critical strain is the applied stress required for unpinning.

关键词： Portevin-Le Chatelier effect dynamic strain aging Al-Mg alloy

cDNA of an arylphorin-type storage protein from Pieris rapae with parasitism inducible expression by the endoparasitoid wasp Pteromalus puparum

在线全文

学校读者我要写书评

暂无评论

Insect Science 2009年第3期16卷 227-236页

作者： Jia-Ying Zhu Gong-Yin Ye qi Fang Cui hu Zunnu-Raen Akhtar State Key Laboratory of Rice Biology Institute of Insect Sciences College of Agriculture and Biotechnology Zhejiang University Hangzhou China

This report presents the cDNA cloning of a storage protein, PraAry, from Pieris rapae and investigates its expression regulated by parasitism of an endoparasitoid wasp Pteromalus puparum. The full-length eDNA of PraAry is 2 270 nucleotides and contains a 2 121 nucleotide open reading frame encoding 707 amino acids with calculated molecular weights of approximately 83 kDa. Analysis of the primary protein sequence revealed that it possesses a signal peptide of 16 amino acids at the N-terminus and contains two highly conserved storage protein signature motifs. According to both phylogenetic analysis and the criteria for amino acid composition, PraAry belongs to the subfamily of arylphorin-type storage protein （1.42% methionine and 18.82% aromatic amino acids）. Reverse transcription- polymerase chain reaction analysis indicated that the transcriptional level of PraAry mRNA in P. rapae pupae fat body is inducible in response to parasitism by P. puparum.

关键词： cloning gene expression parasitism Pieris rapae Pteromalus puparum storage protein

ZOOpt: a toolbox for derivative-free optimization

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

Science China(Information Sciences) 2022年第10期65卷 293-294页

作者： Yu-Ren LIU Yi-qi hu Hong qiAN Chao qiAN Yang YU National Key Laboratory for Novel Software Technology Nanjing University School of Computer Science and Technology East China Normal University

Recent advances in derivative-free optimization allow for efficient approximation of the global optimal solutions of sophisticated functions, such as those with many local optima,non-differentiable and non-continuous functions. This article describes the ZOOpt(zeroth order optimization) toolbox that provides efficient derivative-free solvers that are designed for easy use.

关键词：

Metal Particle Contamination in Gas-insulated Switchgears/Gas-insulated Transmission Lines

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

CSEE Journal of Power and Energy Systems 2021年第5期7卷 1011-1025页

作者： Jian Wang qi hu Yanan Chang Jingrui Wang Ruixue Liang Youping Tu Chuanyang Li qingmin Li State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources and the Beijing Key Laboratory of High Voltage and EMC North China Electric Power UniversityBeijing 102206China. Department of Electrical Engineering Tsinghua UniversityBeijing 100084China.

Metal particle contamination in a gas-insulated switchgear(GIS)or a gas-insulated transmission line(GIL)is an important factor leading to the decline of insulation *** the deterioration mechanism and suppression measures of metal particles on insulation is a key technical problem in enhancing the dielectric strength of GIS/GIL *** this paper,the charge and motion characteristics of metal particles are first *** gas gap breakdown caused by free metal particles and the surface flashover caused by metal particles near or adsorbed on the insulator are then analyzed according to different particle motion patterns and spatial *** in terms of operation managements,the existing methods of particle detection are *** addition,the main inhibition methods of metal particles are introduced from three aspects:particle trap,insulator surface treatment and electrode ***,the prospects in the future research on particle pollution in GIS/GIL are also pointed out.

关键词： Gas gap breakdown GIS/GIL metal particles particle detection particle suppression surface flashover

A New Disaccharide from the Fern Macrothelypteris digophlebia

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

Chinese Chemical Letters 2000年第12期11卷 1063-1064页

作者： Ming hua qiU Jin Ming GAO hu qi LIU Jian Xi FU Kunming Institute of Botany The Chinese Academy of SciencesKunming 650204 Northwest Sci.&Tech.University of Agriculture and Forestry YanglingShaanxi 712100

A new disaccharide, digobiose 1, was isolated from the rhizomes of Macrothelypteris digophlebia (Bak.) Ching var. elegans (koidz.). Its structure which is very similar with that of sucrose was identified as alpha -D-g... 详细信息

关键词： Macrothelypteris digophlebia Disaccharide digobiose.

Density and surface tension of binary mixtures of 1-ethyl-3-methylimdazolium nitrate with alcohols

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2012年第11期23卷 1295-1298页

作者： Feng Yun Zhao Li Ya Liang Jian Ying Wang Yong qi hu College of Chemical and Pharmaceutical Engineering Hebei University of Science and TechnologyShijiazhuang 050018China

New experimental data of densities and surface tensions are presented for the binary mixtures of the ionic liquid 1-ethyl-3- methyl imidazolium nitrate （[EMIM]NO3） with methanol and ethanol. Measurements were performed at 298.15 K and atmospheric pressure, covering the whole composition range. Excess molar volumes VE and the surface tension deviations 8y have been determined. For the excess molar volumes of binary mixture, there is a region of negative VE at low IL mole fraction, passing through a minimum and then VE increases and becomes positive, showing maximum at higher IL mole fraction. It is shown that the surface tension deviations ~y of [EMIM]NO3 ＋ methanol system are positive but those of [EMIM]NO3 ＋ ethanol system are negative over the entire mole fraction range.

关键词： Ionic liquid Density Surface tension Excess molar volume

A New Stilbene Tetramer from Caragana rosea

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2003年第10期14卷 1048-1050页

作者： Guo Xun YANG, Chang qi hu School of Pharmacy, Fudan University, Shanghai 200032 School of Pharmacy Fudan University

Cararosinol A, a new stilbene tetramer, was isolated from Caragana rosea. Its structure has been established on the basis of spectroscopic evidence.

关键词： Caragana rosea Leguminase stilbene tetramer.

A hierarchically structured tin-cobalt composite with an enhanced electronic effect for high-performance CO_(2) electroreduction in a wide potential range

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2023年第1期76卷 462-469,I0012页

作者： Xingxing Jiang Xuan Li Yan Kong Chen Deng Xiaojie Li qi hu Hengpan Yang Chuanxin He Institute of Microscale Optoelectronics College of Chemistry and Environmental EngineeringShenzhen UniversityShenzhen 518060GuangdongChina

Earth-abundant and nontoxic Sn-based materials have been regarded as promising catalysts for the electrochemical conversion of CO_(2)to C1 products,e.g.,CO and ***,it is still difficult for Snbased materials to obtain satisfactory performance at low-to-moderate ***,a simple and facile electrospinning technique is utilized to prepare a composite of a bimetallic Sn-Co oxide/carbon matrix with a hollow nanotube structure(Sn Co-HNT).Sn Co-HNT can maintain>90%faradaic efficiencies for C1 products within a wide potential range from-0.6 VRHE to-1.2 VRHE,and a highest 94.1%selectivity towards CO in an H-type ***,a 91.2%faradaic efficiency with a 241.3 m A cm^(-2)partial current density for C1 products could be achieved using a flow *** to theoretical calculations,the fusing of Sn/Co oxides on the carbon matrix accelerates electron transfer at the atomic level,causing electron deficiency of Sn centers and reversible variation between Co^(2+)and Co^(3+)*** synergistic effect of the Sn/Co composition improves the electron affinity of the catalyst surface,which is conducive to the adsorption and stabilization of key intermediates and eventually increases the catalytic activity in CO_(2)*** study could provide a new strategy for the construction of oxide-derived catalysts for CO_(2)electroreduction.

关键词： Hierarchic structure Tin-cobalt bimetallic oxide Electronic effect CO_(2)electroreduction Wide potential range

Elasto-plastic Analysis of Circular Tunnels in Jointed Rock Masses Satisfy the Hoek-Brown Failure Criterion

在线全文

学校读者我要写书评

暂无评论

Journal of China University of Mining and Technology 2007年第3期17卷 393-398页

作者： SUN Jin-shan LU Wen-bo Zhu qi-hu CHEN Ming State Key Laboratory of Water Resource and Hydropower Engineering Science Wuhan University Wuhan Hubei 430072 China

The relationship between the Hoek-Brown parameters and the mechanical response of circular tunnels is il-lustrated. Closed-form and approximate solutions are given for the extent of the plastic zone and the stress and dis-placement fields under axisymmetrical and asymmetric stress conditions. For the same rock masses and under axisym-metrical stress conditions,the radius of the plastic zone in terms of Hoek-Brown criterion is generally an approximation of the radius in terms of the Mohr-Coulomb criterion. The radius in terms of the Hoek-Brown criterion is larger under low stress conditions. For poor quality rock masses (GSI<25),measures (such as grouting,setting rock bolts,etc.) that improve the GSI of rock masses are effective in improving the stability of tunnels. It is not advisable to improve the sta-bility of the tunnels by providing a small support resistance p through shotcrete,except for very poor quality jointed rock masses. Without reference to the quality of the rock mass,the disturbance factor D should not less than 0.5. Meas-ures which disturb rock masses during tunnel construction should be taken carefully when the tunnel depth increases.

关键词： jointed rock masses circular tunnel general Hoek-Brown failure criterion elasto-plastic analysis con-struction measures