949 resultados para 2,4,6,8-tetraoxaadamantanes


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Experimental electron diffraction patterns and high resolution images were used to determine the space group and unit cell dimensions of 2,3,6,7,10,11-hexakispentyloxytriphenylene. Subsequently the molecular conformation was calculated by energy minimized package in Cerius2. Using this method, we got the HPT crystal structure: space group: P6/mmm; lattice type: hexogonal; the lattice parameters are a = b = 20.3 angstrom, c = 3.52 angstrom, = = 90 degrees, = 120 degrees. The core of HPT is not perpendicular to the column. The angle between a axis and HPT core plane is 9 degrees which cannot be seen in b-c projection. The simulated ED patterns and HREM images are good agreement with the experimental ED patterns and HREM images.

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A new series of mixed conducting oxides, Sr10-n/2BinFe20Om (n = 4, 6, 8, 10), were synthesized by a solid state reaction method, and they have high oxygen permeability. The oxygen permeation rate at 1150 K is 0.41 ml(STD)/ cm(2).min for n = 6 and 0.90 ml(STD)/cm(2).min for n = 10, which is two times higher than that for Sr1-xBixFeO3 (x = 0.5). For the Sr1-xBixFeO3 (x = 0.1, 0.3, 0.5) series, the oxygen flux increases with increasing Bi content. (C) 1998 Elsevier Science Ltd.

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利用TG,DTA,XRD和XPS方法研究了La0.2Ca0.8MnO3催化剂的结构和形成机理.样品用La,Ca,Mn混合硝酸盐制备.随着焙烧温度的升高发生了一系列的固相反应,发现氨氧化催化剂催化活性与生成的CaMnO3含量成正比.在900℃制备的含有CaMnO3,La0.575Ca0.425MNO3,Mn2O3和La2O3的混合物是氨氧化最佳催化剂,活性相是CaMnO3,并具有大量的氧空穴.

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用新型恒界面池法首次研究了二(2,4,4-三甲基戊基)膦酸在盐酸介质中萃取Er(Ⅲ)的动力学,测定了流体线性流速、有机相浓度、水相浓度和酸度、温度及界面面积等因素对萃取速率的影响,提出其速率方程,求出萃取反应的活化能,并对萃取反应机理进行了探讨.

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本文研究了外水相pH值、流动载体浓度、表面活性剂浓度、内相解析酸浓度、水乳比、油内比等因素对二(2,4,4-三甲基戊基)单硫代膦酸(Cyanex302)-上胺205-正庚烷乳状液 膜迁移Sc(Ⅲ)的影响。在一定条件下,Sc(Ⅲ)可以快速而完全地迁移,有可能实现Sc(Ⅲ)与Fe(Ⅲ)、Lu(Ⅲ)的分离。

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在甲烷为反应气的化学电离质谱条件下,质子化的2-羟基-4-邻苯二甲酰亚胺基丁 酸的单分子质谱碎裂产生了m/z 148的碎片离子,表明其碎裂过程发生了氢迁移反应。AM1 分子轨道的理论计算结果为可能的质子化位置提供了理论依据;建立在氘代同位素标记和碰撞诱导解离实验的基础上,我们提出此离子的形成可能同时存在单氢迁移和双氢迁移,一些质谱图中的特征碎片离子为可能的 McLafferty重排和离子/中性(碎片)复合物中间体反应碎裂机理提供了有价值的相关信息。

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本文研究了二(2,4,4-三甲基戊基)磷酸(Cyanex 272)的煤油溶液在不同介质(HCI,HNO_3)中对三价混合稀土的萃取分离性能.观测了平衡水相酸度对萃取平衡的影响,由酸度曲线求出相邻元素的平均分离系数,并考察了酸度对反萃取平衡的影响.比较了HCI和HNO_3介质中,Cyanex 272对混合稀土(Ⅲ)的萃取性能.

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研究了二(2,4,4-三甲基戊基)膦酸(BTMPPA,HA)的正辛烷溶液从盐酸介质中萃取钍(Ⅳ)的机理。在未控制离子强度下,萃取平衡反应为:,在控制离子强度为1.0mol/L时,萃取反应为用饱和法确定的萃合物组成为ThCIA_3.计算了萃取反应的平衡常数及热力学函数。研究了饱和萃合物的IR和NMR谱。

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本文报道9种新的含磷杂环化合物的电子轰击质谱(EIMS),并应用B/E、B2/E联动扫描及精确质量测量技术,探讨了该类化合物的质谱断裂机理,发现骨架重排及开环反应是该类化合物主要的质谱特征,而R2基因对重排过程有很大影响。

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LnCl3 (Ln = Nd, Er) reacts with K2C8H8 to yield the complex (C8H8)LnCl.2THF, which reacts with K(2,4-C7H11) (2,4-C7H11 = 2,4-dimethylpentadienyl) to form (C8H8)Ln(2,4-C7H11).THF. The compound (C8H8)Nd(2,4-C7H11).THF(1) crystallizes from the mixed solvent

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The extraction equilibrium data of sulphuric acid and scandium(III) with bis(2,4,4-trimethylpentyl)phosphinic acid (H[BTMPP]) from sulphuric acid solutions have been obtained. There are two extraction mechanisms of scandium(III) with H[BTMPP] at different

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由于在农药方面的广泛应用,新的有机磷化合物不断被合成。质谱是研究其结构的重要手段之一。总结不同类型有机磷化合物的质谱裂解规律将有助于识别未知的有机磷化合物。本文所研究的5—α—[磷酸基]苄基—2—甲基—4—羟基咪唑衍生物是合成的新型除草剂,质谱未见报道。本工作在低分辨EI谱的基础上,根据高分辨精确质量测量和B/E、B_2/E联动扫描亚稳离子测定数据,研究了该类化合物的质谱断裂机理。着重讨论了该类化合物的共同质谱特征,如:P—C,P—N键的断裂;产物离子的开环反应;产物离子的H重排反应和失去CO的反应等。为该类化合物的结构研究提供依据。

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A method for the specific determination of cobalt based on reversed-phase liquid chromatography with amperometric detection via on-column complex formation has been developed. A water-soluble chelating agent, 1-(2-pyridylazo)-2-naphthol-6-sulphonic acid (PAN-6S), is added to the mobile phase and aqueous cobalt solutions are injected directly into the column to form in situ the cobalt-PAN-6S chelate, which is then separated from other metal PAN-6S chelates and subjected to reductive amperometric detection at a moderate potential of -0.3 V. Because the procedure eliminates the interference of oxygen and depresses the electrochemical reduction of the mobile phase-containing ligand PAN-6S, by virtue of the quasi:reversible electrode process of the cobalt-PAN-6S complex, a low detection limit of 0.06 ng can be readily obtained. Interference effects were examined for sixteen common metal species, and at a 5- to 8000-fold excess by mass no obvious interference was observed. The feasibility of the method as an approach to the specific analysis of cobalt in a hair sample has been demonstrated.

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2-乙基己基膦酸单2-乙基己基酯(HEH/EHP)是目前稀土湿法冶金工业中应用最广泛的萃取剂。但存在重稀土离子反萃取酸度高,某些中、重稀土离子对的分离系数小、选择性不高等缺点。所以研究优于HEH/EHP的新萃取体系已引起人们极大的关注。近年来发现,二(2,4,4-三甲基戊基)膦酸(HBTMPP,HL)有可能是萃取稀土元素的有效萃取剂。由于其分子中不含酯氧原子,使得它的pK。值比HEH/EHP高。因此,用HBTMPP萃取稀土及其它高价

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本文采用PGS-2型2米平面光栅光谱仪和ICP光源联用,样品溶液以乙醇预去溶方式引入ICP,直接同时测定了高纯氧化铒中6个痕量稀土杂质。当样品溶液中Er_2O_3的浓度为5mg/ml时,测定下限为镨和钐为0.0010%,镝、钬、和铥为0.0020%,钇为0.00080%。分析结果令人满意,其相对标准偏差为4.4~6.8%。