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Search Results: 1 - 10 of 63216 matches for " 薛冬峰 "
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电负性概念的新拓展
李克艳,
科学通报 , 2008,
Abstract: 电负性概念1932年由Pauling提出,它与分子中原子的极化率、软硬度、电荷分布等性质之间存在着密切的内在联系,是人们判断物质性质的重要理论依据.随着新材料的发展以及各学科之间的相互交叉与渗透,电负性如今已成为在化学、物理和材料科学等领域均具有广泛应用的基本原子参数.它的发展经历了原子电负性、离子电负性和键电负性三个阶段,其中离子电负性是考虑了原子所处具体环境的价态元素电负性,用于更精确地描述离子和化合物的各种物理化学性质;键电负性是连接原子电负性和材料性质之间的桥梁,它能帮助人们更方便、直接地建立材料的宏观性质和微观结构之间的定量关系.离子电负性和键电负性的提出是对电负性概念的重要拓展,它们在丰富和发展电负性理论的同时,在新材料设计方面发挥了重要作用.该文就电负性概念的研究进展及其在材料研究中的应用作了详细介绍.
从原子到晶体的材料硬度研究
李克艳,
科学通报 , 2008,
Abstract: 基于单位体积的抓电子能量,将硬度概念由原子硬度、离子硬度拓展到了键硬度,在这三个微观层次上研究了材料硬度的本质.研究发现,材料的硬度与其组成原子或离子的硬度没有直接关系,而与其组成化学键的硬度直接相关,本质上取决于其单位体积组成化学键的抓电子能量,并由此建立了鉴别宏观材料硬度的微观模型.该工作有助于人们在原子水平上认识材料硬度的本质,对于探索新型超硬材料具有重要的理论指导意义和实际应用价值.
氧化镁晶须制备及影响因素考查
,邹龙江,闫小星
大连理工大学学报 , 2007,
Abstract: 为了促进氧化镁晶须的规模化生产与工业应用,采用前驱物煅烧法制备了氧化镁晶须.以氯化镁为原料、碳酸钠为沉淀剂制备了结晶良好的水合碳酸镁晶须;控制碳酸镁的热分解条件保持晶须形状不被破坏,在煅烧情况下将其转变为氧化镁晶须.采用X射线衍射仪和扫描电子显微镜对产物的组成、形态和结构进行了表征.结果表明,所得氧化镁晶须直径2~5μm,长度约为60μm.另外,对影响晶须形成的一些主要因素进行了初步探讨,同时简要介绍了利用碱式氯化镁、碱式硫酸镁获得氧化镁晶须的方法,探索性地拓展了氧化镁晶须的工业生产.
超级电容器电极材料的结构设计
,吕派,李克艳
河南大学学报(自然科学版) , 2012,
Abstract: 超级电容器由于具有功率密度大和循环寿命长的优势受到了广泛的关注.电极材料是超级电容器的核心部分,是发展高性能超级电容器的关键要素.电极材料的组成、晶体结构、微纳结构形态等对其电化学性能具有重大影响.赝电容电极材料的性能与晶体内部的孔道结构密切相关,具有大孔道的电极材料其比容量明显高于只含有小孔道的电极材料.合理调控电极材料微纳结构形态如设计多孔结构、中空结构有利于增大电极的电化学活性表面,进而获得更多的电荷存储量,是提高储能性能的有效途径之一.将赝电容电极材料与导电基体复合生长可以提高材料整体的电导率,进
Sn掺杂MoO3的制备、表征及气敏性能
高海燕,王竞一,赵永男,陈昆,
- , 2017,
Abstract: 摘要 以仲钼酸铵和四氯化锡为原料,采用水热法制备了不同Sn掺杂比例的MoO3;利用X射线衍射(XRD),扫描电子显微镜(SEM)和Brunauer-Emmett Teller(BET)测试等手段对材料进行了物相、形貌结构和孔径表征;测试了其对乙醇、二氯甲烷、甲醇、甲醛、甲酸、四氯化碳、氨气和丙酮等气体的传感性能.结果表明,Sn掺杂未改变MoO3的结构;290℃为气体传感测试的最佳测试温度;掺杂后的MoO3对乙醇气体的灵敏度和响应时间均优于纯相MoO3,Sn掺杂摩尔比为5%时效果最好,500 mg/m3测试条件下对乙醇的灵敏度为19.64,响应时间为1.1 s
胶体离子超级电容器
Colloidal Ionic Supercapacitors

陈昆,
CHEN Kun-feng
, XUE Dong-feng

- , 2015, DOI: 10.13208/j.electrochem.150842
Abstract: 摘要 超级电容器具有功率密度大、循环寿命长等优点,但同时面临着能量密度低等缺点. 胶体离子超级电容器是最近开发的一种新型赝电容器,同时具有高功率密度和高能量密度的特点. 胶体离子超级电容器能够充分利用多价态金属阳离子的多电子氧化还原反应,完全释放储存的潜在电能,从而提高超级电容器的能量密度. 由于胶体离子的存在,缩短了电子、离子的扩散长度,加快了氧化还原反应动力学,从而保持高的功率密度. 本文主要介绍胶体离子超级电容器的发展过程、最新研究进展以及需要进一步开展的研究工作,作者希望从一个新的角度去研究发展下一代高性能电化学储能设备,实现新的突破.
Supercapacitors have high power density and long cycle life compared with battery systems, but they still suffer from low energy density at the same time. In order to increase the energy density of supercapacitors, we have developed a new type of pseudocapacitor, called colloidal ion supercapacitor, which can directly use commercial metal salts as electrode materials and form electroactive matter by in-situ electrochemical reactions without the need of additional materials synthesis processes. Colloidal ion supercapacitor can fully utilize the redox reaction of metal cations with multiple oxidation states, which can completely release the stored electrical energy of multiple-valence cations, leading to high energy density. Due to the presence of colloidal cation ions in the colloidal ion supercapacitor, the diffusion length of electrons and ions can be shortened, leading to high redox reaction kinetics and high power density. Both high energy density and high power density can exist in one supercapacitor devices, called colloidal ionic supercapacitor. This review outlines the concept, basis and the development of colloidal ion supercapacitors, the latest research progresses and the facing future challenges. We hope that colloidal ion supercapacitor can advance the development of the next generation of high-performance electrochemical energy storage devices
锂离子电池硅负极材料衰退机理的研究进展
马增胜,周益春,刘军,,杨庆生,潘勇
力学进展 , 2013, DOI: 10.6052/1000-0992-13-066
Abstract: 硅负极材料由于具有非常高的理论比容量,使之成为锂离子电池极具前景的负极替代材料,然而,硅负极材料在充放电过程中会发生非常大的体积变形,这会引起活性材料的破坏失效,严重影响其电化学循环性能,成为制约其在锂离子电池领域广泛应用的最大瓶颈,本文介绍了硅负极材料的不同结构形态及其在充放电过程中电化学性能的退化机理,并综述了充放电过程中的力学性能演化、相关理论分析、数值模拟计算等方面的最新国际研究进展,展望了硅负极材料力学失效方面的研究重点,
深黄被孢霉利用不同碳源产油脂比较
邢大辉?,潘安龙?,桦?,方鸣玉?,谷冉
生物工程学报 , 2010,
Abstract: 本研究主要探讨深黄被孢霉m2菌株对生物质全糖的利用,考察其碳源同化能力、不同碳源下产脂情况以及对玉米皮渣的利用能力。研究结果表明,m2菌株能够利用葡萄糖、木糖、阿拉伯糖和甘露糖进行生长和油脂积累。m2菌株以6%糖浓度的玉米皮渣水解液为底物发酵培养,油脂微生物生物量达18.2g/l,干菌体油脂含量45.7%,单位体积发酵液油脂产量为8.3g/l。
鄂尔多斯盆地北部侏罗系直罗组沉积特征与演化*
Sedimentary characteristics and evolution of the Jurassic Zhiluo Formation in northern Ordos Basin

,赵俊,闫占,杨瑶,赵旭东,赵中平
- , 2017, DOI: 10.7605/gdlxb.2017.06.077
Abstract: 鄂尔多斯盆地东北部发现的多个砂岩型铀矿床均赋存于侏罗系直罗组下段砂岩中。前人对已知铀矿床分布区直罗组的沉积学研究程度相对较高,但对盆地北部直罗组大区域沉积体系展布与演变、物源供给特征等的研究仍较为薄弱。文中在大量钻井资料分析、野外剖面实测等基础上,将盆地北部砂岩型铀矿含矿层段直罗组下段细分为2个亚段。在直罗组中识别出河流和三角洲相沉积,认为直罗组下段下亚段主要发育砾质、砂质辫状河沉积,东北部地区发育辫状河三角洲沉积;直罗组下段上亚段主要发育砂质辫状河和曲流河沉积;直罗组上段则以曲流河沉积为主。结合前人研究工作,认为源岩物质组成、有利沉积相带和气候条件对鄂尔多斯盆地北部砂岩型铀矿的成矿均具有重要控制作用。对盆地北部直罗组沉积特征及其演化的整体认识,可为该区砂岩型铀矿床的进一步勘查提供重要的沉积学依据。
The sandstones in the Lower Member of the Jurassic Zhiluo Formation in northeastern Ordos Basin has been recognized as major reservoirs of uranium in northeastern Ordos Basin. Although previous studies on the sedimentology of the uranium-bearing sandstones in the basin have been usually focused on regional distribution of the uranium-bearing sandstones in northern Ordos Basin received very few attention. Based on large quantities of well data and outcrop measurements in this study, the Lower Member of Zhiluo Formation is divided into two sub-members (J2z1-1, J2z1-2) in northern Ordos Basin. The main types of sedimentary facies identified in the Zhiluo Formation include fluvial facies and deltaic facies. During the deposition of the lower sub-member, the main depositional facies developed include gravelly to sandy braided fluvial deposits and deltaic deposits in the northeastern part of the study area. The main depositional facies gradually changed to sandy braided and meandering fluvial deposits during the deposition of the upper sub-member. Meandering fluvial systems were widely developed during deposition of the upper member, especially toward the top of the member. This study found that the development of uranium ore is mainly controlled by factors such as material composition of the source rock, distribution and evolution of favorable depositional systems, and climate condition. The analysis of facies and the development of the depositional model of the Zhiluo Formation could potentially have important applications for the exploration of uranium deposits in northern Ordos Basin
沙柳纤维素纳米化及其结构测定
Nanostructures of Salix mongolica Cellulose and Structure Determination
 [PDF]

振华, 尚琪
Botanical Research (BR) , 2016, DOI: 10.12677/BR.2016.53012
Abstract: 本文以沙柳枝条为原料,应用硫酸水解法制备了沙柳纳米纤维素,借助现代仪器分析手段分析了沙柳纳米纤维素的结构和性能。研究结果表明,经硫酸水解处理后,沙柳纤维素不再成纤维簇而是分散成许多纤维单丝,其分子链被打断,分解温度较处理前降低,化学成分基本保持不变,纳米纤维素晶体的结晶度较原纤维有一定程度的提高。
The preparation process of nanocellulose was introduced in this paper using Salix branches by a method of sulfuric acid hydrolysis. And then the structure and characteristics of nanocellulose were detected with a series of modern analytic methods using advanced apparatus. The experimental results show that Salix mongolica cellulose was no longer fiber clusters but dispersed into many monofilaments after sulfuric acid hydrolysis. Its molecular chains were interrupted, the de-composition temperature was lower than before treatment, chemical composition remained bas-ically and the crystallinity increased.
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