Studies on Cu-HMS and Solid Base Catalysts for Epoxidation of Olefins in Liquid Phase

环氧化合物是重要的有机合成中间体。以烯烃为原料，经催化环氧化合成相应的环氧化物，是催化化学研究领域的一个重要课题。由于受氧化剂和催化剂价格，以及回收利用和环境污染等因素的制约，目前的烯烃环氧化制备环氧化合物技术仍不能令人满意。因此，发展新型高效的催化剂和催化体系，并且深入理解催化作用机理，受到了广泛关注。本论文选择应用广泛的氧化剂叔丁基过氧化氢和双氧水，主要研究了Cu掺杂介孔分子筛HMS（Cu-HMS）和固体碱烯烃环氧化的催化反应性能，表征了催化剂结构，阐述了结构和性能之间的关联，并提出了可能的反应机理。 研究结果表明，模板法制备的Cu-HMS催化剂在叔丁基过氧化氢存在下可有效地催化苯乙烯环...Epoxidation of olefins is an important class of reaction in view of its industrial applications. However, epoxidation of olefins is usually conducted under expensive oxidant associated with lower efficiency and large amounts of wastes. Therefore, the development of novel and efficient catalysts and catalytic systems are highly demanded from the viewpoints of academic and industrial interests. This...学位：理学博士院系专业：化学化工学院化学系_物理化学(含化学物理)学号：2052006015325

Epoxidation of Styrene Catalyzed by Lanthanum-doped Hydroxyapatite with Hydrogen Peroxide

采用超声辅助的液相沉淀法制备不同lA掺杂量的羟基磷灰石催化剂,采用Xrd,bET,fT-Ir,SEM,EdS和CO2-TPd等手段表征催化剂的结构和表面性质,并考察其在双氧水氧化剂存在下催化苯乙烯环氧化反应的性能.结果表明,随着lA的引入,羟基磷灰石晶格中部分CA2+被lA3+取代,发生一定程度的晶格畸变,并使表面某些碱性位强度和数量有所增加,当lA/(CA+lA)原子比为0.02时,lA掺杂型羟基磷灰石的表面强碱性位数量达到最大,表现出最佳的苯乙烯双氧水环氧化的催化活性,苯乙烯转化率和环氧苯乙烷选择性分别为76.2%和83.5%.lA掺杂型羟基磷灰石可多次循环使用,具有较稳定的结构和催化性能.A series of lanthanum-doped hydroxyapatite(La-HAP) catalysts were prepared.The physicochemical properties of La-HAP were characterized by X-ray diffraction,Fourier transform inferred spectroscopy,scanning transmission electron microscopy-energy dispersive spectroscopy and CO2 temperature-programmed desorption.The catalytic activity of La-HAP for the epoxidation of styrene was investigated with H2O2 as an oxidant.The results indicated that with the introduction of La dopant,some Ca2+ in hydroxyapatite lattice were replaced by La3+,resulting in a lattice distortion and an increase in strength and quantity of surface base.The La-HAP catalyst with a La/(Ca+La) atomic ratio of 0.02 exhibited a maximum number of strong basic sites and provided the highest catalytic activity with 76.2% styrene conversion and 83.5% selectivity to epoxide.Such La-HAP catalyst could be reused several times with considerable stabilities in structure and performance.国家自然科学基金项目(20923004

中小企业信用担保的商业化运作 = The commercial operation of credit trust for small and middium enterprise

This dissertation aims to study the various theories of credit trust and apply the theories to the credit trust in industry China.​Master of Science (Managerial Economics

奉化野鸭形成的人文生态原因浅析[J]

野鸭是水鸟的一种,全世界有很多品种.本文通过查阅资料、实地考察、寻访民间,对奉化地区野鸭形成的人文生态原因进行分析,旨在为奉化野鸭提供理论依据

绿洲农业高效用水技术集成与示范

简要技术说明： 该成果围绕棉花、葡萄、小麦3大作物,从干旱绿洲区作物高效用水和提高作物水分生产效率的目标出发,研究形成了棉花高效用水技术模式3套、葡萄高效用水技术模式1套、小麦优化灌溉节水及配套栽培技术模式1套、干旱绿洲区农业高效用水管理技术模式1套,开发了15项农业节水关键技术和1套“农业灌溉决策支持系统”,筛选出节水配套抗旱小麦品种2个、抗旱棉花品种1个,制定了农业高效用水技术规程7项,研发了专利产品1项、软件著作权登记1项,人才培养12名、发表论文45篇。通过对高效灌溉技术、农艺高效用水技术、高效用水管理技术等3方面的关键技术的集成与创新,研究形成了干旱绿洲区特色作物(棉花、葡萄、..

Expertadvice on the diagnosis and intervention of Chinese developmental dyslexia

发展性阅读障碍是一种以儿童阅读能力显著落后于年龄和智力应有水平为主的障碍，属于具有遗传基础的神经发育性障碍。目前国内对发展性阅读障碍的评估、诊断与干预多出现在科研场合，临床诊疗和教育性质的应用明显不足。专家意见采用专家书面反馈意见和视频会议讨论的形式，以发展性阅读障碍的病因学基础为指导，对发展性阅读障碍的临床表现、诊断流程及干预原则等形成统一意见，旨在为相关专业领域医师和康复专业人员提供参考和帮助，亦为开展对发展性阅读障碍的教育性干预活动提供参考。</p

Measurement of integrated luminosity of data collected at 3.773 GeV by BESIII from 2021 to 2024

We present a measurement of the integrated luminosity e+e- of collision data collected by the BESIII detector at the BEPCII collider at a center-of-mass energy of Ecm = 3.773 GeV. The integrated luminosities of the datasets taken from December 2021 to June 2022, from November 2022 to June 2023, and from October 2023 to February 2024 were determined to be 4.995±0.019 fb-1, 8.157±0.031 fb-1, and 4.191±0.016 fb-1, respectively, by analyzing large angle Bhabha scattering events. The uncertainties are dominated by systematic effects, and the statistical uncertainties are negligible. Our results provide essential input for future analyses and precision measurements

Determination of the number of ψ(3686) events taken at BESIII

The number of ψ(3686) events collected by the BESIII detector during the 2021 run period is determined to be (2259.3±11.1)×106 by counting inclusive ψ(3686) hadronic events. The uncertainty is systematic and the statistical uncertainty is negligible. Meanwhile, the numbers of ψ(3686) events collected during the 2009 and 2012 run periods are updated to be (107.7±0.6)×106 and (345.4±2.6)×106, respectively. Both numbers are consistent with the previous measurements within one standard deviation. The total number of ψ(3686) events in the three data samples is (2712.4±14.3)×10^