66 research outputs found
The Research on Liquidity of China’s Gold Futures Market
摘要 流动性是期货市场赖以生存及运行的基石,是衡量期货市场运行效率及成熟程度的重要指标。市场的流动性为交易者提供了转让及买卖期货的机会,倘若市场缺乏流动性,交易则无法完成,那么市场也就失去了其存在的必要,因此,一个具有较好流动性的市场,对于增强市场参与者的信心、保持市场的正常运转、促进市场规模持续稳定发展、促进资源有效配置,具有重要且深远的意义。中国黄金期货于2008年1月9日在上海期货交易所挂牌交易,但上市以来,期货市场应有的价格发现及套期保值功能并没有得到有效的发挥和体现,参与者对市场的流动性广为质疑。 中国黄金期货市场的流动性状况究竟如何?哪些因素制约了它的流动性?造成中国黄金期货市...Abstract Market liquidity is the existence and running foundation of the futures market,also is an important indicator to measure the efficiency and maturity of the futures market.Because market liquidity provide opportunities for the traders to transfer or trade the futures contracts,if lack it,the transaction will not be completed,then the market will be not necessary to exist,Therefore,a marke...学位:工商管理硕士院系专业:管理学院工商管理教育中心(MBA中心)_工商管理硕士(MBA)学号:1792010115081
Chemical constituents from root of Angelica decursiva
采用HP20大孔吸附树脂、ODS、硅胶柱色谱、Sephadex; LH-20柱色谱和半制备HPLC等色谱分离手段对紫花前胡的化学成分进行研究。结合理化性质及MS,NMR等谱学数据鉴定化合物的结构,从紫花前胡80; %乙醇提取物中分离并鉴定了12个化合物,分别是(9R,10R)-9-acetoxy-8,8-dimethyl-9,10-dihydro-2H,8; H-benzo[1,2-b: 3,4-b']dipyran-2-one-10-yl; ester(1)、补骨脂呋喃香豆精(2)、顺式-3',4'-二千里光酰基-3',4'-二氢邪蒿内酯(3)、(3'R,4'R)-3'-angelo; yloxy-4'-senecioyloxy-3',4'-dihydroseselicalipteryxin(4 )、(+; )-8,9-dihydro-8-(2-hydro-xypropan-2-yl)-2-oxo-2H-furo[2,3h]chromen-9-yl-; 3-methylbut-2-enoate(5)、libanoridin(6)、丝立尼亭(7)、花椒素(8)、crocatone(9)、peuja; ponisinol B(10)、peujaponisinol A(11)、ostenol(12)。其中,化合物1 ~; 5为首次从当归属植物中分离得到,化合物7 ~ 12为首次从紫花前胡中分离得到。The compounds were isolated and purified by HP20 macroporous adsorption; resin,ODS,silica gel,and Sephadex LH-20 column chromatography,as well as; semi-preparative HPLC chromatography from the 80% ethanol extract of the; root of Angelica decursiva, and their structures were identified based; on their physiochemical properties and spectroscopic data. Twelve; compounds were structures were identified as; (9R,10R)-9-acetoxy-8,8-dimethyl-9,10-dihydro-2H,8H-benzo[1,2-b:; 3,4-b']dipyran-2-one-10-yl ester (1),bakuchicin; (2),(3',S,4'S)-disenecioyloxy-3',4'-dihydroseselin; (3),(3'R,4'R)-3'-angeloyloxy-4'-senecioyloxy-3',4'-dihydroseselincalipte; ryxin (4),(+; )-8,9-dihydro-8-(2-hydroxypropan-2-yl)-2-oxo-2H-furo[2,3h]chromen-9-yl-3; -methylbut-2-enoate (5),libanoridin (6),selinidin (7),suberosin; (8),crocatone (9),peujaponisinol B (10),peujaponisinol A (11),and; ostenol (12),respectively. Compounds 1-5 were isolated from the plants; of Angelica genus for the first time. Compounds 7-12 were isolated from; A. decursiva for the first time
表面等离激元“热点”的可控激发及近场增强光谱学
金属纳米结构中特定表面等离激元模式的光学激发及其相互作用是发展高分辨、高灵敏、高精度界面光谱学的物理基础.本文综述了我们研究组近期在表面等离激元共振的光学激发、分类识别、近场增强及在界面光谱学中的应用等方面的进展,主要内容包括:1)利用时域有限差分法,分析了金属粒子-基底体系中SPR\"热点\"产生的物理机制及影响因素,讨论了电模式和磁模式下界面\"热点\"的可控激发及\"热点\"转移的影响因素; 2)利用粒子-金膜体系,实现了可见光频率的表面等离激元磁共振,并利用其形成的\"热点\"进行了表面增强拉曼光谱实验,获得了比常规电模式更高的拉曼增强; 3)通过界面SPR\"热点\"增强二次谐波的实验和理论研究,提出并实现了空间分辨率达到1 nm的等离激元增强二次谐波纳米尺; 4)讨论了针尖增强拉曼光谱及针尖增强荧光体系中的空间分辨率、定向发射等关键共性问题的解决方案.相关研究成果可为界面SPR\"热点\"的可控激发及进一步发展表面增强拉曼、针尖增强拉曼、表面等离激元增强二次谐波等各类高灵敏度,高空间分辨率的界面光谱学方法提供新的思路.国家自然科学基金(批准号:21673192,91850119,11474239);;\n国家重点研发计划(批准号:2016YFA0200601,2017YFA0204902)资助的课题~
Constraint of a ruthenium-carbon triple bond to a five-membered ring
含过渡金属碳三键(M≡C)的金属卡拜化合物是许多有机反应的催化剂或关键中间体。对其合成及性质的研究是金属有机化学的热点之一。由于卡拜碳的sp杂化方式,大部分金属卡拜化合物均为链状结构(卡拜碳键角理想值为180 °),环内金属卡拜化合物因存在很大的环张力而难于合成。夏海平教授课题组发展了由链状多炔(称之为碳龙)构筑碳龙配合物的高效方法(Nature Communications, 2017, 8, 1912),实现了锇杂戊搭炔/烯及其衍生物的一锅法合成。现在,他们把该方法进一步拓展到了第二过渡系金属钌,通过碳龙与市售的RuCl2(PPh3)3反应一锅合成了钌杂戊搭炔I。本研究是碳龙化学的进一步延伸和发展,首次把碳龙化学的金属中心由锇拓展到了其它金属,展示了碳龙化学广阔的发展空间。该研究工作在夏海平教授指导下完成,能源材料化学协同创新中心(iChEM)博士后卓庆德和张弘副教授为共同第一作者。iChEM博士后周小茜、博士生陈志昕、林剑锋、卓凯玥、硕士康慧君、林鑫磊参与了部分实验工作。博士生华煜晖负责理论计算。【Abstract】The incorporation of a metal-carbon triple bond into a ring system is challenging because of the linear nature of triple bonds. To date, the synthesis of these complexes has been limited to those containing third-row transition metal centers, namely, osmium and rhenium. We report the synthesis and full characterization of the first cyclic metal carbyne complex with a second-row transition metal center, ruthenapentalyne. It shows a bond angle of 130.2(3)° around the sp-hybridized carbyne carbon, which represents the recorded smallest angle of second-row transition metal carbyne complexes, as it deviates nearly 50° from the original angle (180°). Density functional theory calculations suggest that the inherent aromatic nature of these metallacycles with bent Ru≡C–C moieties enhances their stability. Reactivity studies showed striking observations, such as ambiphilic reactivity, a metal-carbon triple bond shift, and a [2 + 2] cycloaddition reaction with alkyne and cascade cyclization reactions with ambident nucleophiles.This research was supported by the National Key R&D Program of China (2017YFA0204902) and the National Natural Science Foundation of China (nos. 21490573,21332002, and 21561162001).
研究工作得到国家自然科学基金项目(21490573、21332002 和21561162001)和国家重点研发计划(2017YFA0204902)的资助
Successive modification of polydentate complexes gives access to planar carbon-and nitrogen-based ligands
以碳和氮为键合原子的多齿螯合物是配合物家族中非常重要的一类。具有更高齿数的平面构型NC螯合物实例相对较少,代表性的例子为四齿金属碳卟啉类化合物,这类螯合物以其独特的结构和丰富的物理化学性质引起广泛关注。然而平面五齿、六齿的NC螯合物由于几何构型“拥挤”导致合成难度高,该工作从含三元环内金属卡宾结构的CCCC型碳龙配合物出发,利用经典有机反应(炔烃对金属卡宾的插入反应),成功地实现了CCCCN/NCCCN型平面五齿螯合物的合成。这一研究为高配位型螯合物的合成提供了新思路并为平面五齿螯合物家族添加新成员。特别是,这些高配位型螯合物在可见光和近红外区域均有较好的吸收,表现出良好的光声成像、光热转换及声动力学性能。
该研究工作在张弘教授指导下完成,第一作者为iChEM博士后周小茜。该工作充分体现了多学科协同研究优势:相关化合物的合成、表征及理论计算工作由周小茜博士完成;声动力学性能研究由厦门大学公共卫生学院庞鑫博士及刘刚教授完成;光声成像研究由厦门大学公共卫生学院聂立铭教授完成。iChEM fellow卓庆德博士、博士生卓凯玥、陈志昕参与了部分实验工作。夏海平教授、香港科技大学林振阳教授和南京大学朱从青教授对研究工作给予了大力支持。【Abstract】Polydentate complexes containing combinations of nitrogen and carbon (N and C) ligating atoms are among the most fundamental and ubiquitous molecules in coordination chemistry, yet the formation of such complexes with planar high-coordinate N/C sites remains challenging. Herein, we demonstrate an efficient route to access related complexes with tetradentate CCCN and pentadentate CCCCN and NCCCN cores by successive modification of the coordinating atoms in complexes with a CCCC core. Combined experimental and computational studies reveal that the rich reactivity of metal-carbon bonds and the inherent aromaticity of the metallacyclic skeletons play key roles in these transformations. This strategy addresses the paucity of synthetic approaches to mixed N/C planar pentadentate chelating species and provides valuable insights into the synthesis of carbon-based high-coordinate complexes. Furthermore, the resulting complexes are the examples of organometallic species with combined photoacoustic, photothermal, and sonodynamic properties, which makes them promising for application in related areas.This research was supported by the National Natural Science Foundation of China (Nos. 21572185, 21561162001, and 81571744), the Research Grants Council of Hong Kong (N_HKUST603/15), the Excellent Youth Foundation of Fujian Scientific Committee (2018J06024), and the Fundamental Research Funds for the Central Universities (20720170065).该工作得到国家自然科学基金委、香港研究资助局、福建省自然科学基金、厦门大学校长基金的资助
Combustion Synthesis and Electrochemical Properties of the Small Hydrofullerene C50H10
通讯作者地址: Xie, SY (通讯作者),Xiamen Univ, Coll Chem & Chem Engn, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China
地址:
1. Xiamen Univ, Coll Chem & Chem Engn, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China
2. Xiamen Univ, Coll Chem & Chem Engn, Dept Chem, Xiamen 361005, Peoples R China
3. Xiamen Univ, Sch Life Sci, Xiamen 361005, Peoples R China
电子邮件地址: [email protected]; [email protected] hydrofullerene C50H10 is synthesized by low-pressure benzeneoxygen diffusion combustion. The structure of C50H10 is identified through NMR, mass spectrometry, and IR and Raman spectroscopy as a D5h symmetric closed-cage molecule with five pairs of fused pentagons stabilized by ten hydrogen atoms. UV/Vis and fluorescence spectrometric analyses disclose its optical properties as comparable with those of its chloride cousin (C50Cl10). Cyclic and square-wave voltammograms reveal that the first reduction potential of C50H10 is more negative than that of C50Cl10 as well as C60, with implications for the utilization of C50H10 as a promising electron acceptor for photovoltaic applications.973 projects 2011CB935901
NSFC 21031004
21021061
2077310
Design of Physical Simulation System for Satellite Flexible Rotating Panels Based on Flotation
挠性附件运动时产生的弹性振动是影响空间飞行器指向精度和控制性能的主要原因.因此,在地面对控制系统抑制振动的性能进行验证具有重要意义.由于太阳帆板低频且长度较大,在地面构建大范围运动的空间微重力环境,耗资及难度极大。本文提出一种基于等效主轴惯量与挠性频率的卫星挠性旋转帆板挠性模拟器,基于气浮法设计了低摩擦与微重力环境的物理仿真系统,并建立了模拟器的动力学模型,等效模拟了卫星挠性旋转帆板的振动特性,降低了卫星挠性旋转帆板地面微重力运动环境模拟的难度,实现了对其控制算法抑制振动性能的有效及高经济性测试.仿真结果表明,模拟器可以通过简单操作实现参数的平滑改变以模拟不同参数及结构的卫星挠性旋转帆板,且具..
Design of Physical Simulation System for Satellite Flexible Rotating Panels Based on Flotation
挠性附件运动时产生的弹性振动是影响空间飞行器指向精度和控制性能的主要原因.因此,在地面对控制系统抑制振动的性能进行验证具有重要意义.由于太阳帆板低频且长度较大,在地面构建大范围运动的空间微重力环境,耗资及难度极大。本文提出一种基于等效主轴惯量与挠性频率的卫星挠性旋转帆板挠性模拟器,基于气浮法设计了低摩擦与微重力环境的物理仿真系统,并建立了模拟器的动力学模型,等效模拟了卫星挠性旋转帆板的振动特性,降低了卫星挠性旋转帆板地面微重力运动环境模拟的难度,实现了对其控制算法抑制振动性能的有效及高经济性测试.仿真结果表明,模拟器可以通过简单操作实现参数的平滑改变以模拟不同参数及结构的卫星挠性旋转帆板,且具..
Structure Optimization of Captive Trajectory System Based on Multi-Objective Genetic Algorithm
针对国内已有的CTS系统堵塞度大、俯仰偏航角度小(精度低)的问题,设计了一种新型的CTS机构。首先对CTS系统的整体结构设计和运动原理进行了介绍。然后对俯仰机构的设计方案进行选择,在此基础上完成了转动框架的外形设计。最后基于多目标遗传算法理论和参数化建模技术,对转动框架进行了优化设计,优化后转动框架质量减小、堵塞度减小。结果表明,多目标遗传算法能通过计算在可行域内快速求出转动框架优化设计的最优解集,优化效率高、效果好,对CTS机构的进一步研发具有理论价值和工程意义,此种方法也为以后类似的结构设计和优化提供了参考
介质阻挡放电功率相关因素分析
采用Q-VlISSAJOuS图形法对介质阻挡放电功率进行测量,研究放电电压V、放电环境气压、放电电源频率f及占空比、电极间隙等因素对介质阻挡放电功率的影响。实验结果表明在其它条件不变的情况下,放电功率随着放电环境的真空度增大而减小,随着电极间隙的增大而减小,随着占空比的增大而增大;放电功率和电源频率之间的关系与放电电极的固有谐振频率有关,电源频率越接近放电电极的谐振频率,放电功率越大。研究结果表明,选择合适的参数,可以提高介质阻挡的放电功率,为进一步提高介质阻挡放电的等离子体密度提供实验支持。福建省自然科学基金项目(A1010014
- …
