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1.
镧系元素的煤地化效应——以渭北中熟煤为例 总被引:1,自引:0,他引:1
用数理统计的方法研究了渭北中熟煤中REE在残留烃-无机矿物的赋存规律,发现REE在煤中热解残留烃和矿物质之间有明显的分配规律. 其中LREE和HREE又各自呈现出不同的分布和赋存特征. 但无论是LREE还是HREE,这种赋存分布规律都决定于其离子半径及内部的电子构型变化规律. 因而出现LREE随着原子序数增大,其在有机的残留烃中赋存规律性增强,而HREE随着原子序数的增大,其在无机矿物中赋存规律性增强的现象. 这就是本研究所发现的"镧系元素的煤地化效应". 相似文献
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浙北富硒土壤地球化学特征与生物学效应 总被引:2,自引:0,他引:2
通过对杭嘉湖平原富硒区研究,发现区内富硒土壤主要分布在环湖平原区,土壤具有特殊的地球化学性质,表现为土壤酸性,土壤硒全量0.3~0.5 mg/kg,有机质含量高、重金属含量低,土壤质地较黏重,土壤硒与有机质关系密切,而与土壤pH相关性不明显等特点。在土壤有机质丰富和氧化条件下,农产品中硒含量较高,重金属低于限量标准,具有较好的开发远景。 相似文献
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提出拓扑化学行为概念,把对化合物性质最具影响力的因素归纳为拓扑生长力和拓扑阻滞力。根据该原理,利用价电子轨道能量对价电子距离矩阵进行修正。研究表明OET(轨道能量拓扑指数)对镧系元素和锕系元素的物理化学性质具有良好的应用,尤其是对尚未借助QSPR(定量结构性质关系)手段进行研究的光谱性质。LOO CV(留一法交叉检验)的结果验证了模型的良好稳定性和预测能力,采用的检验参数有:PRESS/SSY,SEPCV,RCV,SPRESS 和PSE,其中PRESS/SSY比值介于0.000 6和0.114 8之间。与文献进行比较,本文方法所得结果与之接近或更好。研究显示正是基于拓扑化学行为才有本文方法良好和较广的应用。 相似文献
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对比了渭北晚古生代5号煤样品酸处理前后微量元素含量的变化。结果表明,按其量化表征的煤中微量元素酸脱除率划分,44个微量元素可分为五类,它们在元素周期表中有着明显的分布规律:Ⅰ型,为煤中典型的易酸脱除微量元素,主要占据于元素周期表中第Ⅰ、Ⅱ主族元素位置,按电子构型,属s区;Ⅱ型,为煤中较易酸脱除微量元素;Ⅲ型,为煤中较难酸脱除微量元素,主要占据在第Ⅲ、Ⅴ、Ⅵ、Ⅷ副族元素位置上,按电子构型,属d区和f区左半部;Ⅳ型,是难酸脱除的微量元素,主要占据在第Ⅳ、Ⅴ主族元素位置,(稀土元素部分在第Ⅲ副族)按电子构型,属p区和f区中部;Ⅴ型,为典型的最难酸脱除微量元素,主要占据在第Ⅱ、Ⅲ、Ⅳ副族位置,按电子构型,属d区的前半部、ds区和f区的右半部。煤中微量元素的酸脱除难易的大小,在元素周期表的横向、纵向和对角线方向,亦有一定的变化规律。 相似文献
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在生理及更高pH下以α-氨基酸或EDTA作为配体,抑制Ln(Ⅲ)水解得到了一类镧系元素-羟基自组装多核配合物。该类多核配合物以具有类立方烷结构的[Ln4(μ~3-OH)~4]^8^+为基本结构单元,可以单体{[Ln~4(μ~3-OH)~4]^8^+},共顶点的“环状四聚体”{[Ln~1~2(μ~3-OH)~1~6]^2^0^+}或“环状五聚体”{[Ln~1~5(μ~3-OH)~2~0]^2^5^+}的形式稳定存在。本文报道了该类配合物的合成、结构及性质,探讨了卤素离子对“环状四聚体”及“环状五聚体”形成的模板效应,并初步证明了类立方烷结构单体,“环状四聚体”及“环状五聚体”乃是生理及更高pH下镧系元素的稳定存在形式。同时还证明了直接水解镧系元素硝酸盐或高氯酸盐能得到一类以正八面体结构的[Ln~6(μ~6-O)(μ~3-OH)~8]^8^+]为骨架的多核配合物。磁性测定表明,室温下各配合物的类立方烷结构中的镧系离子间无明显磁交换。 相似文献
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在促进基础学科与应用学科交叉融合以加快“高等学校双一流”建设的时代背景下,以“神奇的甲基化效应”为例阐述医用化学与药物化学课程内容的融合,从化学结构的角度综合分析了甲基的引入对药物代谢动力学性质、分子构象或脂溶性的改变,从而减轻药物的毒性、增强药物活性、改善成药性等。将综合性、应用性强的药物化学与理论性强的医用化学进行融合,使学生既掌握化学的经典原理,又能从新药设计的实际情况出发,构建对学生职业成长有意义的知识体系,以期克服传统教学模式下理论知识与实际应用脱节的缺点,促进教学质量的提高。 相似文献
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镧系元素配位化学新领域: 生理及更高pH下镧 系元素-羟基自组装多核配合物 研究 总被引:6,自引:0,他引:6
在生理及更高pH下以α-氨基酸或EDTA作为配体,抑制Ln(Ⅲ)水解得到了一类镧系元素-羟基自组装多核配合物。该类多核配合物以具有类立方烷结构的[Ln4(μ~3-OH)~4]^8^+为基本结构单元,可以单体{[Ln~4(μ~3-OH)~4]^8^+},共顶点的“环状四聚体”{[Ln~1~2(μ~3-OH)~1~6]^2^0^+}或“环状五聚体”{[Ln~1~5(μ~3-OH)~2~0]^2^5^+}的形式稳定存在。本文报道了该类配合物的合成、结构及性质,探讨了卤素离子对“环状四聚体”及“环状五聚体”形成的模板效应,并初步证明了类立方烷结构单体,“环状四聚体”及“环状五聚体”乃是生理及更高pH下镧系元素的稳定存在形式。同时还证明了直接水解镧系元素硝酸盐或高氯酸盐能得到一类以正八面体结构的[Ln~6(μ~6-O)(μ~3-OH)~8]^8^+]为骨架的多核配合物。磁性测定表明,室温下各配合物的类立方烷结构中的镧系离子间无明显磁交换。 相似文献
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天津沿海潮间带沉积物中稀土元素的地球化学特征 总被引:5,自引:1,他引:5
研究了天津沿海潮间带沉积物中稀土元素(REE)的地球化学特性以及污染条件下稀土元素的环境行为特征,通过稀土分布模式特征探讨了潮间带沉积物的物质来源.结果表明(1)潮间带沉积物中14种稀土含量总和的均值为164.5mg@kg-1,但各岸段又有不同.大致以海河口为界,北部明显高于南部,均值分别为182和150mg@kg-1,均明显高于海洋沉积物稀土含量;(2)海岸带沉积物稀土形态分布特征是自北向南残渣态比例逐渐下降,铁锰氧化物态和有机结合态比例逐渐增高,与黄河、长江等大河相比,残渣态和碳酸盐态比例都显著偏低;(3)稀土元素分布模式均为轻稀土富集、铕中度亏损型,与沿海排污河及内陆大河沉积物稀土分布模式相似,而与海洋大陆架沉积物稀土分布模式有显著差别. 相似文献
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煤可溶烃中一种特殊的稀土元素地球化学现象
——以渭北中熟煤为例 总被引:1,自引:0,他引:1
用数理统计方法研究了渭北中熟煤中稀土元素(REE)在可溶烃和无机矿物中的赋存规律。结果表明,REE在可溶烃和矿物质之间有明显的互补关系,其中,轻稀土(LREE)和重稀土(HREE)又各呈现出不同的分布和赋存特征。但无论是LREE还是HREE,这种赋存分布规律都决定于其离子半径及内部的电子构型变化规律。LREE随着原子序数增大,其在有机的可溶烃和无机矿物中赋存规律性减弱,而HREE随着原子序数的增大,其在可溶烃和无机矿物中赋存规律性增强。这种“互补”和同步消长的关系在可溶烃各族组分之间也存在,并对煤成烃有一定的潜在作用。这是作者以前发现的“稀土元素煤地化效应”的另一种表现形式。 相似文献
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Anthranilates of Tb-Lu prepared in the reaction of the rare earth hydroxides withortho-aminobenzoic acid (anthranilic acid) have the general formulaLn(C6H4NH2COO)3·2H2O whereLn=Tb, Dy, Ho, Er, Tm, Yb, Lu. The water molecules in the hydrated compounds are in the outer coordination sphere. On heating in air at 493K dehydration occurs and the anhydrous anthranilatesLn(C6H4NH2COO)3 are formed. On the basis of the IR spectra it was found that the metal in dihydrated anthranilates was simultaneously coordinated through amino and carboxyl groups whereas in anhydrous anthranilates only through the bidentate carboxyl group. From X-ray analysis it was stated that the anthranilatesLn(C6H4NH2COO)3·2H2O are isostructural, whereas the anhydrous compoundsLn(C6H4NH2COO)3 are isostructural in the two groups Tb-Er and Tm-Lu.
Die Komplexe der schweren Selteneerdmetalle mit Orthoaminobenzoesäure
Zusammenfassung Zur Darstellung der Verbindungen des TypsLn(C6H4NH2COO)3·2H2O (mitLn=Tb bis Lu) wurde die berechnete Menge vonLn(OH)3 und C6H4NH2COOH-Lösung gemischt und bei 363K schnell zur Kristallisation gebracht. Die Produkte werden schnell abfiltriert, mit Wasser gewaschen und bis zur Gewichtskonstanz getrocknet. Die VerbindungenLn(C6H4NH2COO)3·2H2O sind isostrukturell mit der Dichte ungefähr 1.6g·cm–1 und geringer Löslichkeit in Wasser bei Raumtemperatur. Beim Erhitzen folgt zunächst Entwässerung bei 493 K, später Zersetzung zu Tb4O7 undLn 2O3. Die wasserfreien VerbindungenLn(C6H4NH2COO)3 sind isostrukturell in 2 Strukturtypen: Tb-Er and Tm-Lu. Die Infrarotspektren von wasserfreien Verbindungen und Doppelhydraten wurden registriert. Es wurde festgestellt, daß die Koordinierung der Seltenerdmetalle mit Liganden in den Dihydraten sowohl durch die Amino- als auch durch Carboxylgruppen erfolgt. In den wasserfreien Komplexen tritt die Koordinierung nur durch Carboxylgruppen auf.相似文献
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The [LnI2(THF)3]2(-C10H8) complexes were obtained by reactions of LnI3(THF)3 (Ln = Ce, Pr, Nd, or Gd) with lithium and excess naphthalene. The magnetic moments of these complexes correspond to the oxidation state +3 of the metal atoms. The YbII complex, [YbI(DME)2]2(-C10H8), was synthesized by the reaction of YbI2(DME)2 with an equimolar amount of naphthalenelithium.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2573–2574, October 1996. 相似文献
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Extraction of lanthanides from aqueous solution by using room-temperature ionic liquid and supercritical carbon dioxide in conjunction 总被引:2,自引:0,他引:2
Mekki S Wai CM Billard I Moutiers G Burt J Yoon B Wang JS Gaillard C Ouadi A Hesemann P 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(6):1760-1766
For the first time, the study of a three-step extraction system of water/ionic liquid/supercritical CO2 has been performed. Extraction of trivalent lanthanum and europium from an aqueous nitric acid solution to a supercritical CO2 phase via an imidazolium-based ionic liquid phase is demonstrated, and extraction efficiencies higher than 87 % were achieved. The quantitative extraction is obtained by using different fluorinated beta-diketones with and without the addition of tri(n-butyl)phosphate. The complexation phenomenon occurring in the room-temperature ionic-liquid (RTIL) phase was evidenced by using luminescence spectroscopy. 相似文献
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Ferenc Wieslawa Walków-Dziewulska Agnieszka 《Journal of Thermal Analysis and Calorimetry》2003,74(2):511-519
The physico-chemical properties and thermal stability in air of the light lanthanide 2,3- and 3,5-dimethoxybenzoates were
studied and compared in order to observe if there is influence of the position of -OCH3 substituents in benzene ring on their properties, mainly on their thermal stability. The complexes of both of two series
are crystalline, hydrated or anhydrous salts with colours typical of Ln3+ ions. The carboxylate group shows the different coordination modes. It may coordinate as a bidentate, chelating or tridentate
chelating-bridging ligand. The thermal stabilities of 2,3- and 3,5-dimethoxybenzoates of light lanthanides were studied in
the temperature range 293-1173 K. The solubilities of 2,3- and 3,5-dimethoxybenzoates of these elements in water at room temperature
are in the orders of 10-3-10-2 mol dm-3 and 10-4 mol dm-3, respectively. The various positions of -OCH3 groups in benzene ring influences some physico-chemical properties of these compounds.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Yu. G. Galyametdinov G. I. Ivanova I. V. Ovchinnikov K. Binnemans D. V. Bruce 《Russian Chemical Bulletin》1999,48(2):385-387
Liquid-crystalline cationic complexes of lanthanides with azomethines containing the alkyl sulfate anion as the counterion
were synthesized. The temperatures of existence of the mesophase of the complexes with the alkyl sulfate anion were by 80–100°C
lower than those of similar complexes with the Cl− and NO3
− counterions.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 387–389, February, 1999. 相似文献
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Naixing Wang Zhikun Si Jinghe Yang Wei Jiang Weian Liang Zhendong Li Gaoying Du Guoqing Zhang 《Mikrochimica acta》1997,127(1-2):71-75
The absorption spectra of 4f electron transitions of the neodymium and erbium complexes with benzoyl-indan-1,3-dione and cetylpyridinium chloride have been studied by conventional and derivative spectrophotometry. The second-derivative spectrum has been used to eliminate the interference of the other lanthanides, and to increase the sensitivity by a further factor of 4–6. Beer's Law is obeyed for 6–29 g/ml Nd and 7–33 g/ml Er. The relative standard deviations evaluated from 10 independent determinations of 5.0 g/ml Nd and Er were 1.1% (Nd) and 1.6% (Er). The detection limits obtained from the sensitivity of the calibration graphs and 3s
b, (standard deviation of the blank,n = 11) were 0.63 g/ml Nd and 0.61 g/ml Er. The quantification limits (10s
b) were 2.1 g/ml Nd and 2.0 g/ml Er. A method for the direct determination of neodymium and erbium in rare earth mixtures with good accuracy and selectivity is proposed. 相似文献
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《Arabian Journal of Chemistry》2023,16(2):104510
To deeply understand the mechanism of inert gases in inhibiting coal spontaneous combustion, the effects of dry air, CO2, and N2 on coal spontaneous combustion were analyzed experimentally. To this end, bituminous coal prepared from Dongrong No. 2 Coal Mine was considered the research object. Based on the adsorption configuration of the oxygen-containing coal, the displacement behavior of O2 by CO2 /N2 was studied using the grand canonical Monte-Carlo (GCMC) and molecular dynamics (MD) methods. The obtained results show that the injection of CO2 and N2 reduces the ability of spontaneous combustion of coal. It is found that among the studied gases, CO2 has a stronger inhibition effect on coal spontaneous combustion, which increases the temperature of CO occurrence by 5℃, decreases the concentration of CO by 29.91%, and inhibits low-temperature oxidation of coal. From the microscopic point of view, CO2 /N2 gases can effectively displace O2 by diffusion and occupying adsorption sites. It is found that after the injection of CO2, the concentration of O2 molecules increases significantly in the vacuum layer. Compared with N2, injection of CO2 increases the diffusion activation of O2 by 5.89%. This indicates that the injection of an inert gas significantly reduces the oxygen absorption capacity of coal, thereby decreasing the coal-oxygen combination reaction and preventing the spontaneous combustion of coal. The performed analyses demonstrate that CO2 outperforms N2 in restraining the spontaneous combustion of coal. 相似文献