检索结果-南通市图书馆

Science China Chemistry 2024年第3期67卷 953-962页

作者： Yuan-Qing Gu Hong-Xin Long Dan-Dan Zhang Mei-feng ruan Guo-Kai Liu School of Pharmacy Shenzhen University Medical SchoolShenzhen UniversityShenzhen 518055China

Development of practical and versatile electrophilic difluoromethylating reagent is still a grand challenge so far due to its inherent instability or low ***,we report the design and synthesis of difluoromethyl phenoxathiinium tetrafluoroborate(PT-CF_(2)H^(+)BF_(4)^(-)) as a novel difluoromethylating reagent,which proves to be a bench-stable,general,powerful and versatile reagent with divergent·CF_(2)H,CF_(2)H^(+),and:CF_(2) *** use of this reagent,we demonstrated a vast array of difluoromethyl radical transfer reactions via diverse pathways involving photocatalyst-free visible-light induction,visible-light photoredox catalysis and visible-light mediation single electron transfer of EDA ***,the green and highly effective CF_(2)H^(+) and:CF_(2) transfer reactions were also readily accomplished.

关键词： difluoromethyl phenoxathiinium salt versatile difluoromethylating reagent difluoromethyl radical difluoromthyl cation difluorocarbene

Recent advances in producing hollow carbon spheres for use in sodium−sulfur and potassium−sulfur batteries

在线全文

学校读者我要写书评

暂无评论

新型炭材料（中英文） 2024年第5期39卷 824-843页

作者： QI Zi-xin LUO Sai-nan ruan Jia-feng YUAN Tao PANG Yue-peng YANG Jun-he ZHENG Shi-you School of Materials and Chemistry University of Shanghai for Science and TechnologyShanghai 200093China Department of Materials Science Fudan UniversityShanghai 200433China

Sodium-sulfur(Na-S)and potassium-sulfur(K-S)batteries for use at room temperature have received widespread attention because of the abundance and low cost of their raw materials and their high energy ***,their development is restricted by the shuttling of polysulfides,large volume expansion and poor *** overcome these obstacles,an effective approach is to use carbon-based materials with abundant space for the sulfur that has sulfiphilic sites to immobilize it,and a high electrical *** carbon spheres(HCSs)with a controllable structure and composition are promising for this *** consider recent progress in optimizing the electrochemical performance of Na-/K-S batteries by using these ***,the advantages of HCSs,their synthesis methods,and strategies for preparing HCSs/sulfur composite materials are ***,the use of HCSs in Na-/K-S batteries,along with mechanisms underlying the resulting performance improvement,are ***,prospects for the further development of HCSs for metal−S batteries are presented.

关键词： Hollow carbon sphere Sodium-sulfur batteries Shuttle effect Potassium-sulfur batteries Electrochemical performance

在线全文

学校读者我要写书评

暂无评论

大型钢框架建筑塔吊布置与安全管理研究

工程技术研究 2024年第7期9卷 119-121页

作者：阮峰中交四航局江门航通船业有限公司广东江门529145

塔吊是建筑工程垂直、水平运输的主要工具之一,大型公共建筑工程通常需要配置多台塔吊,以满足施工需求,塔吊的合理布置成为此类工程项目管理的重难点。文章结合某大型钢框架公共建筑施工中群塔吊的布置与管理,总结了一套适用该类项目的... 详细信息

塔吊是建筑工程垂直、水平运输的主要工具之一,大型公共建筑工程通常需要配置多台塔吊,以满足施工需求,塔吊的合理布置成为此类工程项目管理的重难点。文章结合某大型钢框架公共建筑施工中群塔吊的布置与管理,总结了一套适用该类项目的群塔吊布置方法,对类似工程有一定的借鉴作用。

关键词：大型钢框架建筑公共建筑施工群塔布置安全管理

桂北龙胜硅质岩的地球化学、Si-O同位素特征及沉积环境研究

在线全文

学校读者我要写书评

暂无评论

矿物岩石地球化学通报 2024年第5期43卷 946-959页

作者：陈忻沙鑫阮青锋于海燕桂林理工大学地球科学学院广西隐伏金属矿产勘查重点实验室

本文通过对桂北龙胜地区出露的硅质岩进行系统的地球化学及Si-O同位素分析以探讨其成因、物质来源及其沉积环境意义。结果表明，龙胜硅质岩的SiO2含量为92.09%～99.27%,Si/Al值为412.93～3841,Al2O3/（Al2O3+Fe2O3）值为0.03～0.58,Al/... 详细信息

本文通过对桂北龙胜地区出露的硅质岩进行系统的地球化学及Si-O同位素分析以探讨其成因、物质来源及其沉积环境意义。结果表明，龙胜硅质岩的SiO2含量为92.09%～99.27%,Si/Al值为412.93～3841,Al2O3/（Al2O3+Fe2O3）值为0.03～0.58,Al/（Al+Fe+Mn）值为0.04～0.66;MnO/TiO2值为0.43～26.64；∑REE为0.20～2.37,LREE/HREE值为1.76～11.18,U/Th值为1.31～18.52。龙胜硅质岩的球粒陨石标准化配分模式呈右倾型，显示Eu负异常，且Ce具有较强正异常，北美页岩和澳大利亚后太古宙页岩标准化配分模式呈平坦型，具有较强的Eu正异常和较弱的Ce负异常特征；Th、U、Pb、Nb、Ta、Hf、Rb等不相容元素严重亏损，表明龙胜硅质岩是热水沉积成因；龙胜硅质岩δ30Si的值为–0.36‰～0.78‰，δ18O值为17.42‰～18.24‰，说明其为大陆边缘-半深海环境下沉积而成的热水成因硅质岩。综合分析认为，龙胜硅质岩沉积于765～760 Ma的新元古代，同时期大规模的岩浆活动以及裂谷盆地的形成与演化，指示龙胜硅质岩在热水沉积作用下形成，且沉积于大陆边缘海-半深海盆地之间。

关键词：硅质岩地球化学 Si-O同位素沉积环境龙胜地区

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

环泊酚应用于颅内动脉瘤栓塞术的效果

中国新药与临床杂志 2024年第8期43卷 607-611页

作者：梅凤美曾琼陆军阮义峰吴姗姗南京医科大学附属脑科医院麻醉科江苏南京210029

目的观察环泊酚在颅内动脉瘤栓塞术中的麻醉效果。方法选择择期行颅内动脉瘤栓塞术的患者120例,ASA分级Ⅰ~Ⅱ级,随机分为对照组和试验组,每组60例。麻醉诱导时采用咪达唑仑0.04 mg·kg^(-1)、舒芬太尼0.25μg·kg^(-1)、环泊酚0.4 mg·k... 详细信息

目的观察环泊酚在颅内动脉瘤栓塞术中的麻醉效果。方法选择择期行颅内动脉瘤栓塞术的患者120例,ASA分级Ⅰ~Ⅱ级,随机分为对照组和试验组,每组60例。麻醉诱导时采用咪达唑仑0.04 mg·kg^(-1)、舒芬太尼0.25μg·kg^(-1)、环泊酚0.4 mg·kg^(-1)(试验组)或丙泊酚2.0 mg·kg^(-1)(对照组)及罗库溴铵0.6 mg·kg^(-1)。麻醉维持2组均持续泵注瑞芬太尼1μg·kg^(-1)·h^(-1)、顺阿曲库铵0.1 mg·kg^(-1)·h^(-1),试验组加用环泊酚0.8 mg·kg^(-1)·h^(-1),对照组加用丙泊酚5 mg·kg^(-1)·h^(-1)。术中调整泵注速度使脑电双频指数(BIS)维持在40~60,观察生命体征和BIS的变化,记录麻醉诱导时间﹑苏醒时间﹑拔管后Ramsay镇静评分等,观察不良反应发生情况。结果2组麻醉前、麻醉诱导后、气管插管后、手术结束时、气管导管拔除后各观察时点收缩压(SBP)﹑舒张压(DBP)和心率(HR)比较,均无显著差异(P>0.05),试验组手术结束时的BIS显著低于对照组(P<0.05)。麻醉诱导期间对照组SBP﹑DBP和HR的波动值显著大于试验组(P<0.05)。试验组苏醒时间长于对照组,镇静药物总用量少于对照组,均有显著差异(P<0.05)。试验组麻醉诱导后低血压﹑插管后高血压以及注射痛的发生率显著低于对照组(P<0.05)。结论环泊酚应用于颅内动脉瘤栓塞术具有良好的镇静效果,患者术中血流动力学波动更趋平稳,术后不良反应发生率低。

关键词：环泊酚丙泊酚颅内动脉瘤栓塞治疗性

桂西巴平石英矿床成因:来自流体包裹体、C-H-O同位素及稀土元素证据

在线全文

学校读者我要写书评

暂无评论

矿物岩石地球化学通报 2024年第2期43卷 326-342页

作者：何丽佳阮青锋邱志惠程诗渤周子涵桂林理工大学地球科学学院广西桂林541006 广西师范大学化学与药学学院广西桂林541004

为探讨碳酸盐岩区石英矿床的成因机理,对桂西巴平石英矿床中的水晶、脉石英、方解石和赋矿围岩(白云岩)进行了分析测试。流体包裹体岩相学及激光拉曼分析表明,水晶和脉石英中的流体包裹体主要为气液两相包裹体,可见富CO_(2)两相及三相... 详细信息

为探讨碳酸盐岩区石英矿床的成因机理,对桂西巴平石英矿床中的水晶、脉石英、方解石和赋矿围岩(白云岩)进行了分析测试。流体包裹体岩相学及激光拉曼分析表明,水晶和脉石英中的流体包裹体主要为气液两相包裹体,可见富CO_(2)两相及三相包裹体,包裹体的液相成分为H_(2)O和CO_(2),气相成分为H_(2)O、CO_(2)和少量N_(2)。流体包裹体的均一温度为160~312℃,盐度为0.41%~6.16%NaCl_(eqv),属CO_(2)-H_(2)O-NaCl体系的中-低温、低盐度、低密度热液流体。水晶和脉石英的稀土元素配分模式呈轻稀土富集右倾型,具有明显的Eu、Tb、Ho、Yb负异常,推测其母岩浆流体是亏损Eu的,成矿流体与深部的隐伏花岗岩体有关。方解石的稀土元素配分模式呈明显右倾型式,具有轻稀土富集和轻微的Eu正异常,指示其形成于氧化环境,白云岩的Ce负异常指示其形成于低温氧化环境。水晶及脉石英的δD_(SMOW)和δ^(18)OH_(2)O分别为-75.5‰~-54.1‰和5.72‰~7.06‰,指示成矿流体主要为岩浆热液;方解石及白云岩的δ^(13)CPDB分别为-3.92‰~-3.35‰和2.41‰~3.59‰,δ^(18)O_(SMOW)分别为18.84‰~19.13‰和23.25‰~27.45‰,表明方解石的CO_(2)主要来源于围岩的海相碳酸盐岩。成矿过程中深部岩浆热液沿深大断裂侵入,富Si流体沿断裂、裂隙运移过程中与碳酸盐岩围岩发生水岩相互作用,大量的CO_(2)进入到热液中。成矿环境的pH值、压力的降低及流体沸腾作用促使方解石和SiO_(2)开始沉淀,并随着温度和压力持续降低,H_(4)SiO_(4)溶解度不断降低,SiO_(2)大量沉淀,最后形成石英矿床。

关键词：流体包裹体 C-H-O同位素成矿流体石英矿床矿床成因

MECHANISM RESEARCH FOR 3D NON-AXISYMMETRIC THIN-WALL TUBE OFFSET SPINNING

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2006年第2期19卷 217-222页

作者： KUANG Weihua XIA Qinxiang ruan feng　 Faculty of Material and Energy Guangdong University of TechnologyGuangzhou 510006 China College of Mechanical Engineering South China University of TechnologyGuangzhou 510640 China

Difference of offset spinning with conventional symmetric spinning is analyzed. A 3D FEM model for offset tube neck-spinning is established and the spinning process is simulated by means of ANSYS software. Dynamic boundary and contact problems in simulation are solved. Transient stress distribution of contact area, transient strain distribution of nodes in typical section and strain distribution of the workpiece at last are attained, the place and the cause of crack are analyzed. Strain variation curves with time of offset spinning and conventional spinning are compared. It shows the mechanism difference between offset spinning and conventional spinning. In addition, simulation results show how strain distribution of typical section, thickness of some typical nodes, axial extension in left section and force of three rollers change with time. According to the study of the variation curve, material flow law along radial, tangential and axial direction is attained and the whole spinning process is studied. The simulation results discover that offset distance is the key to manufacture offset non-symmetric tube, and process parameters change with spinning angle. Experiment data really reflect different process parameters＇ influence on conventional symmetric and offset spinning force. Experiments accord well with simulation.

关键词： Offset Symmetric Neck-spinning Simulation Mechanism

从“认知内驱力”视角谈情境化试题的核心素养价值--以福建省中考物理学科试题为例

在线全文

学校读者我要写书评

暂无评论

物理教学探讨 2024年第6期42卷 51-56页

作者：阮志锋黄李炮福建省莆田擢英中学福建莆田351100 福建省仙游第一中学福建仙游351200

随着新版义务教育物理课程标准的实施,中考命题方式发生变化,强调依据标准命题,落实立德树人,促进学生核心素养发展。以福建省中考物理试题为例,从学生认知内驱力角度出发,分析合理的试题情境对核心素养形成的重要性。研究发现,情境化... 详细信息

随着新版义务教育物理课程标准的实施,中考命题方式发生变化,强调依据标准命题,落实立德树人,促进学生核心素养发展。以福建省中考物理试题为例,从学生认知内驱力角度出发,分析合理的试题情境对核心素养形成的重要性。研究发现,情境化试题有助于激发学生的兴趣和主动性,提升其综合能力和品德素养,促进学生核心素养的培养。因此,素养立意下的试题情境化在初中物理教育中具有重要意义,意在为教师提供有益的教学参考。

关键词：初中物理情境化试题认知内驱力核心素养

Finite Element Simulation on the Spin-forming of the 3D Non-axisymmetric Thin-Walled Tubes

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2006年第2期22卷 261-268页

作者： Qinxiang XIA Baixiang LIANG Saiiun ZHANG Xiuquan CHENG feng ruan Collegeof Mechanical Engineering South China University of Technology Guangzhou 510640 China Guangzhou Civil Aviation College Guangzhou 510403 China

The roller movement trace for the 3D non-axisymmetric thin-walled tubes is a complex space curve. Besides the roller rotation caused by contact with the blank, the roller rotates around the workpiece together with the main spindle, and also moves simultaneously along the direction of the revolution radius. The method to correctly establish the finite element （FE） models of the metal spinning is based on the MSC. MARC software was introduced. The calculation formulas considering both the revolution and rotation of the roller were obtained by the mathematical deduction. The saving calculation points m should be a multiple of 4 for one revolution of the roller around the workpiece to obtain the maximum forming force for the spinning of the 3D non-axisymmetric thin-walled tubes. The simulation results conform well to the experimental ones for several spinning methods; the maximum error is less than ±15%.

关键词： Non-axisymmetric parts Spin-forming Finite element analysis (FEA) Multi-path spinning

BO_(2)-F^(+)Centers in the Radiation-damaged YCOB Crystals

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2000年第12期17卷 896-898页

作者： ruan Yong-feng Hiroshi NAKAO Takatomo SASAKI Department of Physics Tianjin UniversityTianjin 300072 Department of Electrical Engineering Osaka UniversityOsaka 565-0871Japan

An intense paramagnetic EPR signal generated from x-ray-irradiated,powdered YCOB crystals was observed at the liquid nitrogen temperature for the first *** peaks,located at the positions where the effective g factor equals to 1.992,1.986,1.980,1.974 and 1.965,labeled as A,B,C,D and E respectively,were *** is believed that the peaks A,B,C and D generated from the BO_(2)-F^(+)center which is a single electron trapped in an oxygen vacancy which was originally occupied by an O^(2-)ion bonded to a(BO3)^(3-)anion *** peak E is thought of coming from Y2+ions that are formed by the Y^(3+) ions trapping *** mechanism for the formation of the radiation-induced defects in the YCOB crystals is suggested.

关键词： Crystal occupied trapping