检索结果-南通市图书馆

Anomeric configuration-dependence of the Lattrell-Dax epimerization from D-glucose to synthetically useful D-allose derivatives

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Natural Medicines 2020年第10期18卷 723-728页

作者： NING Yun-Zhan QIN Chun-Jun sun wen-bin FU Jun-Jie HU Jing YIN Jian Key Laboratory of Carbohydrate Chemistry and Biotechnology Ministry of EducationSchool of BiotechnologyJiangnan UniversityWuxi 214122China Wuxi School of Medicine Jiangnan UniversityWuxi 214122China

D-Allose and its derivatives play important roles in the field of health care and food nutrition. Pure and well-defined Dallose derivatives can facilitate the elucidation of their structure-activity relationship as an essential step for drug design. The LattrellDax epimerization, refers to the triflate inversion using nitrite reagent, is known as valuable method for the synthesis of rare D-allose derivatives. Here, the influence of protecting group patterns on the transformation efficiency of D-glucose derivatives into synthetically useful D-alloses and D-allosamines via the Lattrell-Dax epimerization was studied. For C3 epimerization of D-glucose derivatives bearing O2-acyl group, an anomeric configuration-dependent acyl migration from O2 to O3 was found. In addition, a neighbouring group participation effect-mediated SN1 nucleophilic substitution of the D-glucosamine bearing C2 trichloroacetamido(TCA) group in the Lattrell-Dax epimerization was dependent upon anomeric configuration. Thus, the effect of anomeric configuration on the LattrellDax epimerization of D-glucose suggests that β-D-glucosides with low steric hindrance at C2 should be better substrates for the synthesis of D-allose derivatives. Significantly, the efficient synthesis of the orthogonally protected D-allose 13 and D-allosamine 18 will serve well for further assembly of complex glycans.

关键词： D-allose D-allosamine Epimerization Anomeric configuration Acyl migration

在线全文

学校读者我要写书评

暂无评论

加筋土挡土墙CAD设计

辽宁工程技术大学学报（自然科学版） 2006年第5期25卷 711-713页

作者：孙文彬蒋洋淮阴工学院土木工程系江苏淮安223001

为快捷地设计加筋挡土墙和设计分析的可视化,介绍了加筋土挡土墙的设计基本理论和计算机辅助设计软件(Computer-aided design,CAD)的设计思想、软件结构和软件功能。该软件以Windows为开发平台,利用Visual Basic 6.0开发成界面友好的交... 详细信息

为快捷地设计加筋挡土墙和设计分析的可视化,介绍了加筋土挡土墙的设计基本理论和计算机辅助设计软件(Computer-aided design,CAD)的设计思想、软件结构和软件功能。该软件以Windows为开发平台,利用Visual Basic 6.0开发成界面友好的交互系统,实现了加筋土挡土墙计算机辅助设计(CAD)软件由传统的参数计算转变为具有人性化界面的可视化。实践应用证明,面向对象的可视化加筋土挡土墙计算机辅助设计软件将有助于工程人员迅速、准确地进行档土墙设计,并提出优化的设计方案。

关键词： VB 加筋土挡上墙计算机辅助设计

Numerical simulation on radiation and energy of blast-induced seismic waves in deep rock masses

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2022年第2期29卷 645-662页

作者： YANG Jian-hua WU Ze-nan sun wen-bin YAO Chi WANG Qiu-hui School of Civil Engineering and Architecture Nanchang UniversityNanchang 330031China Power China Jiangxi Electric Power Engineering Co. Ltd.Nanchang 330096China

With regard to blasting in deep rock masses,it is commonly thought that an increase in the in-situ stress will change the blast-induced rock crack propagation and ultimately affect rock ***,little attention has been given to the change in seismic wave radiation when the fractured zone changes with the in-situ *** this study,the influences of in-situ stress on blast-induced rock fracture and seismic wave radiation are numerically investigated by a coupled SPH-FEM simulation *** results show that the change in blast-induced rock fracture with in-situ stress has a considerable effect on the seismic wave energy and *** the in-situ stress level increases,the size of the fractured zone is significantly reduced,and more explosion energy is transformed into seismic energy.A reduction in the size of the fractured zone(seismic wave source zone)results in a higher frequency content of the seismic *** a nonhydrostatic in-situ stress field,blast-induced cracks are most suppressed in the direction of the minimum in-situ stress,and thus the seismic waves generated in this direction have the highest energy *** addition to P-waves,Swaves are also generated when a circular explosive is detonated in a nonhydrostatic in-situ stress *** S-waves result from the asymmetrical release of rock strain energy due to the anisotropic blast-induced fracture pattern.

关键词： blasting in-situ stress seismic wave rock fracture SPH-FEM

Stability analysis of underground surrounding rock mass based on block theory

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2020年第10期27卷 3040-3052页

作者： LIN Jian-yun ZUO Yu-jun WANG Jian ZHENG Lu-jing CHEN bin sun wen-ji-bin LIU Hao Mining College Guizhou UniversityGuiyang 550025China School of Resource and Environmental Engineering Guizhou UniversityGuiyang 550025China School of Resources and Safety Engineering Central South UniversityChangsha 410083China Priority Research Centre for Geotechnical Science and Engineering The University of NewcastleCallaghanNSW2308Australia

Evaluation of the performance of existing support in underground tunnels is of great importance for production and *** on field investigation,the shape and number of joints and fractures were investigated in the mining ***,the stability of each structural blocks is analyzed by 3D wedge stability analysis software(Unwedge).Moreover,a new analysis method based on critical block theory is applied to analyze the stability of excavated laneways in continuous and discontinuous rock and monitor the stress changes in a fractured tunnel rock *** test results indicate that the 3D wedge stability analysis software for underground excavation can evaluate deep tunnel ***,there is no direct relation between the size of the block and the instability of the *** support method,on large and thick key blocks,needs to be *** a broken tunnel section,U-shaped steel support can effectively promote the stress state of the surrounding *** monitoring the surrounding rock,it is proven that the vibrating string anchor stress monitoring system is an efficient and real-time method for tunnel stability evaluation.

关键词： block theory Unwedge analysis software stress monitoring system support evaluation

在线全文

学校读者我要写书评

暂无评论

基于变换基阵的三维SDCT表示方法

通信学报 2012年第4期33卷 163-168页

作者：孙文邦唐海燕孙文斌程红空军航空大学特种专业系吉林长春130022 空军航空大学航空理论系吉林长春130022 安徽工业大学数理学院安徽马鞍山243002

对三维SDCT(sub-matrices discrete cosine transform)表示方法进行了研究。首先,定义了4种新的三维矩阵运算方法;其次,在构建了变换基阵的基础上,详细描述了三维SDCT的运算原理;最后,对三维SDCT算法特性进行了分析。通过理论分析表明,... 详细信息

对三维SDCT(sub-matrices discrete cosine transform)表示方法进行了研究。首先,定义了4种新的三维矩阵运算方法;其次,在构建了变换基阵的基础上,详细描述了三维SDCT的运算原理;最后,对三维SDCT算法特性进行了分析。通过理论分析表明,三维SDCT运算方法使三维DCT的表达简洁,理解容易,计算便捷。

关键词： SDCT 变换基阵运算特性表示方法

过氧化氢氧化乙基紫催化光度法测定痕量铬(Ⅵ)

在线全文

学校读者我要写书评

暂无评论

冶金分析 2006年第6期26卷 62-64页

作者：孙文斌吴芳辉安徽工业大学数理学院安徽马鞍山243002 安徽工业大学数理学院

研究了在硫酸介质中,利用铬(Ⅵ)催化过氧化氢氧化乙基紫的褪色反应,建立了催化光度法测定痕量铬的新方法。方法线性范围为0.05-0.60 mg/L,检出限为1.02×10-4mg/L,对2μg铬(Ⅵ)标准溶液平行测定10次,相对标准偏差为1.11%。在氟化钠及硫... 详细信息

研究了在硫酸介质中,利用铬(Ⅵ)催化过氧化氢氧化乙基紫的褪色反应,建立了催化光度法测定痕量铬的新方法。方法线性范围为0.05-0.60 mg/L,检出限为1.02×10-4mg/L,对2μg铬(Ⅵ)标准溶液平行测定10次,相对标准偏差为1.11%。在氟化钠及硫脲存在下,多数常见离子不干扰测定,方法可直接用于废水及钢样中铬(Ⅵ)的测定。

关键词：催化光度法铬乙基紫过氧化氢

First observation results of Macao Science Satellite-1 on lightning-induced electron precipitation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Earth Sciences 2025年第1期68卷 1-10页

作者： Yongping WANG Yixin sun Qiugang ZONG Gaopeng LU Xudong GU Ze-Jun HU bin LI Key Laboratory for Polar Science Ministry of Natural Resources Polar Research Institute of China Institute of Space Physics and Applied Technology Peking University State Key Laboratory of Lunar and Planetary Science Macau University of Science and Technology School of Earth and Space Sciences University of Science and Technology of China School of Electronic Information Wuhan University

The Medium-energy Electron Spectrometers(MES) is a space-borne instrument onboard Macao Science Satellite-1(MSS-1) dedicated to monitoring the typical charged particle radiation characteristics in the satellite orbit and the process of their occurrence and development, including short bursts of lightning-induced electron precipitation(LEP).This paper presents the first results of the LEP measurements by the MSS-1.47 LEP events are identified with the routine operation for 3 months since satellite launch, all within the range of 1.5

关键词： Lightning-induced electron precipitation Inner radiation belts Energetic electrons Macao Science Satellite-1

基于QTM的全球离散格网变形分布及收敛分析

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

中国矿业大学学报 2005年第4期34卷 438-442页

作者：赵学胜孙文彬陈军中国矿业大学资源与安全工程学院北京100083 国家基础地理信息中心北京100044

介绍了球面四元三角网(QTM)的剖分原理;用纬线代替大圆弧线以改进QTM的传统细化方法,既减小了格网的变形量,又提高了格网数据与地理坐标的转换效率;根据实验数据,分析了在不同层次QTM格网中其面积和边长的变异性分布特征.结果表明:随着... 详细信息

介绍了球面四元三角网(QTM)的剖分原理;用纬线代替大圆弧线以改进QTM的传统细化方法,既减小了格网的变形量,又提高了格网数据与地理坐标的转换效率;根据实验数据,分析了在不同层次QTM格网中其面积和边长的变异性分布特征.结果表明:随着剖分层次的增加,1)格网面积的变形特征逐渐接近于正态分布;2)三角形最大/最小面积的比值和最大/最小边长的比值越来越大,但其增长速度越来越小,最终收敛到1.73和1.86.

关键词：地理信息系统四元三角网变形分布收敛特征全球离散格网

一种基于遗传算法的TSP问题多策略优化求解方法

在线全文

学校读者我要写书评

暂无评论

地理与地理信息科学 2016年第4期32卷 1-4页

作者：孙文彬王江中国矿业大学(北京)地球科学与测绘工程学院北京100083

针对遗传算法求解TSP问题解质量不高的缺陷,该文提出并设计了一种基于遗传算法的多策略优化求解方法。首先,应用最邻近法构建TSP的初始解;接着将路径长度作为适应度评价指标,构建基于遗传算法的TSP初始解优化方法,并根据试验结果确定适... 详细信息

针对遗传算法求解TSP问题解质量不高的缺陷,该文提出并设计了一种基于遗传算法的多策略优化求解方法。首先,应用最邻近法构建TSP的初始解;接着将路径长度作为适应度评价指标,构建基于遗传算法的TSP初始解优化方法,并根据试验结果确定适合的遗传算法参数;然后,针对遗传算法易陷入局部最优的缺陷,借助去交叉和小角操作进一步优化TSP解路径;在此基础上,将遗传算法进行并行化处理,通过增加遗传算法的多样性提高TSP解质量。最后,应用标准测试集(TSPLIB)进行试验,结果表明:该算法能有效提高TSP解的质量,经并行遗传算法、去交叉和小角优化后各测试数据集TSP解误差率平均下降了22.57%;解的误差率均在7.94%以内,质量明显优于最邻近法、插入法、2-Opt优化等传统方法;在节点数多的测试数据集中算法也获得了良好加速性能,8进程时算法加速比达2.51。

关键词： TSP问题遗传算法优化策略 2-Opt