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在本文中,提出了极性基团电子相关能贡献的定义,并在MP2-OPT2/6-311++G(d)水平上计算了CH3(CH2) mOH( m=0-4)体系中HO-、CH3-和-CH2-基团电子相关能贡献值。计算结果表明,在CH3(CH2) mOH( m=0-4)体系中端基HO-、CH3-基团电子相关能贡献值 Ecorr(HO-)和 Ecorr(cH3-)的数值随着 m的增加而逐渐减小。同一体系中a -CH2-基团电子相关能贡献值大于其它-CH2-基团电子相关能贡献值,在CH3(CH2) mOH( m=1-4)体系中,距离端基HO-基团越远的-CH2-基团其电子相关能贡献值越小;通过计算结果可以推断,在CH3(CH2) mOH体系中随着 m的逐渐增加,相对远离端基HO-的-CH2-基团的电子相关能贡献值表现出收敛趋向并将趋于不变,此-CH2-基团可看作一个标准的亚甲基而且其 Ecorr(-cH2-)的数值在CH3(CH2) mOH体系中具有传递性。在MP2-OPT2/6-311++G(d)水平上对CH3(CH2) mOH( m=2-4)体系的计算结果和应用Gaussian 98程序在MP2/6-311++G(d)//HF/6-311++G(d)水平上对CH3(CH2) mOH( m=2-7)体系的计算结果均表明,体系总电子相关能与( m-1)呈 中 m是体系中亚甲乙烯基的数值。 相似文献
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本文报导了用多种不同的钛催化体系对卤代烃进行还原反应的结果。观察到二氯二茂钛、某些二氯二(取代茂基)钛和二茂钛甲基烯丙基配合物在异丙基溴化镁的存在下对卤代烃的还原是高效均相催化剂。在某些情怳下,有机溴化物和碘化物可以在非常温和的条件下被定量地还原。我们比较了不同类型的卤代芳烃、卤代烷烃和二卤代烃的还原,对催化剂用量和反应温度的影响也进行了研究。文中讨论了反应机理,认为以Cp2TiH为催化反应的活性种,先是RX对Cp2TiH氧化加成,再发生RH的还原消除,然后在格氏试剂的存在下Cp2TiH再生,从而构成催化循环。 相似文献
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深入理解辐照条件下氢同位素与CO2反应的微观机制,可为聚变堆氘氚燃料循环工艺的优化设计提供数据支撑。基于此,采用第一性原理计算研究了等离子体放电条件下H2和CO2的微观反应机制,研究了不同温度和氢同位素效应对反应过程的影响。通过内禀反应坐标(IRC)算法结合反应过渡态获得4条初始反应路径,并对比研究了生成产物CH4及CH3OH的2条路径在热力学上的容易程度,以及不同氢同位素对各个反应的影响。研究发现,氚的自发衰变或等离子体中的高能电子都会诱导氢同位素与CO2发生反应,形成CO、H2O、CH4及CH3OH等产物;在高能电子诱导CO2的离解后,由4条初始反应路径组成的复杂反应可以自持发生,且该复杂反应中存在2种倾向;升高反应温度对CO2转化为有机物(CH4和CH3OH)具有一定的促进作用。 相似文献
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一些具有NASICON型网格结构的固体电解质具有高的电导率和好的稳定性,NASICON的意思是Na Super Ionic Conductor[1]。当NaZr2(PO4)3中P5 被Si4 部分取代时便可以得到具有NASICON结构的Na1 xZr2SixP3-xO12体系,其具有高的钠离子电导率。然而有相同结构的Li1 xZr2SixP3-xO12体系的离子电导率却很低,这是因为Li 半径太小,而NASICON三维网格结构的离子通道太大,两者不匹配而使电导率下降[2]。但当LiZr2(PO4)3中Zr4 被离子半径小些的Ti4 取代,所得LiTi2(PO4)3的通道就与Li 半径相匹配,适合于锂离子的迁移,从而使其电导率… 相似文献
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phase diagrams of KCl-KBO2-K2CO3, K2MoO4-KBO2-K2CO3, and K2WO4-KBO2-K2CO3 ternary systems were studied by a calculation-experimental method and differential thermal analysis (DTA). The coordinates
of ternary eutectics were determined to be E
1: 622°C, 8.5 mol % KBO2, 56.5 mol % KCl, and 35 mol % K2CO3; E
2: 710°C, 23 mol % KBO2, 43 mol % K2CO3, and 34 mol % K2MoO4; E
3: 710°C, 23 mol % KBO2, 43 mol % K2CO3, and 34 mol % K2WO4. The specific heats of melting of the eutectics were determined. 相似文献
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S. F. Kudryashov O. S. Kudryashova L. P. Filippova 《Russian Journal of Inorganic Chemistry》2010,55(4):594-601
Solubility in the Na2Cr2O7-(NH4)2Cr2O7-K2Cr2O7-H2O four-component water-salt system at 25, 50, and 75°C was studied for the first time. Phase field boundaries for individual
salts and potassium and ammonium dichromate solid solutions, monovariant lines, and invariant points were determined. Experimental
data were used to optimize the looped isohydric process of potassium dichromate preparation involving additional salts. 相似文献
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Richard R. Schrock 《Journal of organometallic chemistry》1976,121(3):373-379
MMe5(dmpe) (M = Nb or Ta, dmpe = Me2PCH2CH2PMe2) reacts with H2 (500 atm) and dmpe in THF at 60°C to give MH5(dmpe)2? NbH5(dmpe)2 readily reacts with two mol of CO or ethylene (L) to give NbHL2(dmpe)2. The exchange of the hydride ligand with the ethylene protons in NbH(C2H4)2(dmpe)2 is not rapid on the 1H NMR time scale (60 MHz) at 95°C. 相似文献
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W. Li M. Wang Z. H. Li X. F. Shang H. Wang Y. W. Wang Y. B. Xu 《Russian Journal of Electrochemistry》2007,43(11):1279-1283
The lithium-ion-conducting inorganic solid electrolytes in the oxide systems Li2O-SiO2-P2O5 and Li2O-TiO2-SiO2-P2O5 were prepared by the solid-state reaction, and the electrolyte pellet made by cold-pressing method had diameter of 13 mm
and was about 1 mm thick. Phase identification and surface morphology of the products were carried out by X-ray diffraction
and scanning electron microscopy. Ionic conductivity of the pellets was investigated through ac impedance. The results show
that the adding of other cations can improve the ionic conductivity of the solid electrolyte, and the sintering temperature
and duration can influence the ionic conductivity. The maximum ionic conductivity in the samples is 9.9 × 10−4 S/cm in the Li2O-TiO2-SiO2-P2O5 system.
Original Russian Text ? W. Li, M. Wang, Z.H. Li, X.F. Shang, H. Wang, Y.W. Wang, Y.B. Xu, 2007, published in Elektrokhimiya,
2007, Vol. 43, No. 11, pp. 1341–1345. 相似文献
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本文用高精度数字式振荡管密度计测定了288K至318K温度范围内Li2SO4 + Na2SO4 + H2O和 Li2SO4 + K2SO4 + H2O三元体系的密度。混合溶液的离子强度范围从0.1到4.5 mol.kg–1,混合溶液中Na2SO4和K2SO4的离子强度分数为0.2,0.4,0.6和0.8。用密度实验值拟合得到了不同温度下Pitzer离子相互作用模型混合参数θV和 ψV,模型的计算值与实验值的偏差在±0.002 g.cm–3以内。用Pitzer模型计算了不同离子强度下三元体系的混合体积。 相似文献
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Zh. A. Kochkarov M. V. Khubaeva I. A. Shogenov Z. L. Khakulov 《Russian Journal of Inorganic Chemistry》2011,56(6):946-953
The phase diagrams of the NaBO2-NaCl-Na2CO3, NaBO2-Na2CO3-Na2MoO4, NaBO2- Na2CO3-Na2WO4, and NaBO2-NaCl-Na2WO4 ternary systems were studied by a calculation-experimental method and differential thermal analysis. The coordinates of ternary
eutectics were determined: E
1: 612°C, 16 mol % NaBO2, 42 mol % NaCl, and 42 mol % Na2CO3; E
2: 568°C, 12 mol % NaBO2, 28 mol % Na2CO3, and 60 mol % Na2MoO4; E
3: 575°C, 12 mol % NaBO2, 32 mol % Na2CO3, and 56 mol % Na2WO4; E
4: 628°C, 8 mol % NaBO2, 20 mol % NaCl, and 72 mol % Na2WO4; and E
5: 655°C, 9 mol % NaBO2, 53 mol % NaCl, and 38 mol % Na2WO4. 相似文献
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采用传统固相反应工艺,按化学计量比合成BaO-Al_2O3-SiO_2(BAS)-x%(w/w) Li_2O-Na_2O-B_2O3-SiO_2(LNBS)(x=0,1,2,3,4)陶瓷。研究不同LNBS烧结助剂添加量对BAS系微波介质陶瓷的结构和介电性能的影响。通过Clausius-Mossotti公式计算讨论了BAS理论与实验介电常数(εr)的差异。研究结果表明:LNBS烧结助剂中Li+进入钡长石Al3+位或单四元环(S4R)间隙,并产生了O_2-空位或Ba2+空位,从而促进BAS六方相向单斜相的转变。添加适量的LNBS烧结助剂后,BAS陶瓷的烧结温度从1 400℃降低到1 325℃,同时BAS陶瓷样品密度、品质因数(Qf)值以及频率温度系数(τf)得到改善。当x=1,烧结温度为1 325℃时,可获得综合性能相对较好的BAS陶瓷,其介电性能:Qf=35 199 GHz,εr=6.37,τf=-1.613×10-5℃-1。 相似文献
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H.J. Breunig O. Moldovan U. Rosenthal R.A. Varga 《Journal of organometallic chemistry》2011,696(2):523-526
Reactions of [Cp2Ti(btmsa)] (btmsa = bis(trimethylsilyl)acetylene) with R4Sb2 (R = Me, Me3Si) give [Cp2TiSbMe2]2 (1) or [Cp2TiSb(SiMe3)2]2 (2) respectively. [Cp2TiCl]2·2Mes4Sb2 (3) is serendipitously formed from [Cp2Ti(btmsa)] and Mes2SbH containing NH4Cl traces. 相似文献
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The novel, 1D semiconductor (H2NC4H8NCH2CH2NH2)(HNCH2CH2NH2)3Zn2Ge2Se8 has been synthesized under solvothermal conditions using N-(2-aminoethyl)piperazine as solvent and templating agent at 200 °C. The material was characterized by single crystal and powder X-ray diffraction, IR and Raman spectroscopy and thermogravimetric analysis. The compound consists of 1D anionic [Zn2Ge2Se8]4− chains made of alternating edge-shared [ZnSe4] and [GeSe4] tetrahedra that charged balanced by one N-(2-aminoethyl)piperazinium and three piperazinium cations. The optical properties were investigated with solid state UV–Vis/near IR spectroscopy and the results show that the solid is a medium gap semiconductor with an absorption edge at 1.8 eV. 相似文献