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991.
992.
用XPS研究我国一些煤中有机硫的存在形态 总被引:4,自引:2,他引:4
本文用电子能谱(xps)方法研究了我国九个不同牌号煤中有机硫的存在形态,并得到这些煤中各种不同形态硫的结合能数据。根据Lindberg等人所做模型化合物结果,给出了这些煤中硫元素结构能的化学归属。各种煤中硫的存在形态是不同的,有硫醇、硫醚、双硫醚、硫杂环、硫桥和取代基上的硫等。这一研究结果为今后研究煤的分子结构及脱硫方法提供了重要的科学依据。 相似文献
993.
994.
The lattice model of associated solutions was used to calculate the concentration dependences of the chemical shifts of13C magnetic nuclei in the acrylamide molecule in water—DMSO solvent. Each pair of bonds between the acrylamide group containing
a magnetic nucleus and the neighboring solvent molecule was assumed to additively contribute to the change in the chemical
shift of the nucleus in question. The new approach affords the same accuracy in describing the experimental data at any ratios
of the solution components. It was shown that the chemical shifts and the excess heat of mixing of the water—DMSO binary solution
can be simultaneously described using the same set of energy parameters of the model. The model makes it possible to employ
experimental data on chemical shifts for studying intermolecular interactions in solutions.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1983–1987, October, 1998. 相似文献
995.
基于SVR和k-近邻群的组合预测在QSAR中的应用 总被引:1,自引:0,他引:1
为提高定量构效关系(QSAR)研究的预测精度,发展了一种新的基于支持向量机回归(SVR)非线性筛选分子结构描述符、基于k-近邻群的非线性组合预测方法.首先以均方误差(MSE)最小为原则,以留一法通过多轮末尾淘汰实施分子结构描述符的非线性SVR汰选并给出最优核函数和相应保留描述符;其次基于待测样本与训练样本保留描述符向量的欧氏距离,以不同k-近邻群子模型双重留一法预测值反映样本集的异质性;然后基于MSE最小,以留一法通过多轮末尾淘汰实施近邻群子模型的非线性SVR汰选并给出最优核函数和相应保留子模型;最后基于保留子模型以双重留一法实施组合预测.以取代苯胺和苯酚类化合物对大型溞的QSAR实例验证表明:新方法在所有参比模型中预测精度最高,且能更精细地反映描述符与化合物毒性间的非线性关系,具结构风险最小、非线性、适于小样本,能有效克服过拟合、维数灾和局极小,非线性筛选描述符和子模型,非线性组合预测,自动选择最优核函数及其相应参数,泛化推广能力优异、预测精度高等诸多优点,在QSAR研究中有广泛应用前景. 相似文献
996.
V. V. Dotsenko S. G. Krivokolysko A. N. Chernega V. P. Litvinov 《Russian Chemical Bulletin》2007,56(7):1431-1436
A new stereoselective method for the synthesis of trans-isomers of 2-amino-4-aryl-5-benzoyl-4,5-dihydrothiophene-3-carbonitriles was proposed. The method involves base-catalyzed
reactions of phenacyl thiocyanate with 3-(het)aryl-2-cyanoprop-2-enethioamides. (4R,5S/4S,5R)-2-Amino-5-benzoyl-4-(2-chlorophenyl)-4,5-ihydrothiophene-3-carbonitrile was structurally characterized by X-ray diffraction
analysis.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1379–1383, July, 2007. 相似文献
997.
Electrochemical and electrocatalytic properties of thin films Au(111-25 nm), which are quasi-single-crystal electrodes 25
nm thick made of gold with the (111) preferential orientation, and same electrodes modified with a monolayer (ML) of palladium
are studied in 0.1 M solutions of HClO4 and H2SO4 employing voltammetric techniques and surface enhanced infrared reflection absorption spectroscopy (ATR-SEIRAS). Spectroscopic
experiments demonstrate strong adsorption of electrolyte species (H2O, OHads, anions) on the Pd surface. The weak and reversible adsorption of CO on Au(111-25 nm) does not change the interfacial-water
structure. Adsorption of CO on the Pd-modified film results in an irreversibly adsorbed CO adlayer stabilized by co-adsorbed
isolated water species. Various electrooxidation mechanisms are discussed. Electrochemical and spectroscopic investigations
on the adsorption and electrooxidation of HCOOH on bare and 1 ML Pd-Au(111-25 nm) electrodes reveal that electrooxidation
proceeds in both cases via a direct or dehydrogenation pathway. This mechanism involves the formation of formate as intermediate,
which is detected by in situ ATR-SEIRAS. The reactivity on Pd-modified surfaces is higher than on bare gold. The specifically
adsorbed anions (sulfate/bisulfate) and the oxide formation on the substrate surface lower the reactivity for CO and HCOOH
on both surfaces.
Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 11, pp. 1312–1329.
Based on the report delivered at the 8th International Frumkin Symposium “Kinetics of the Electrode Processes,” October 18–22,
2005, Moscow.
The text was submitted by the authors in English. 相似文献
998.
Thin films of bis(dimethylglyoximato)palladium(II) complex of polycrystalline structure were prepared by sublimation in a vacuum at 140 °C, on glass and p-Si substrates. The films were characterised by spectral optical absorption, energy dispersion X-ray fluorescence (EDXRF), and X-ray diffraction (XRD) methods. After characterisation, metal-insulator (complex)-semiconductor MIS devices were fabricated to measure the frequency dependence of ac-conductivity in a range of 5-100 kHz. Data of ac-measurements follow the correlated barrier-hopping CBH model, from which one of the fundamental absorption peaks, the minimum hopping distance, and other parameters of the CBH model were determined, connecting and relating the optical, structural, and electrical measurements. The dielectric properties of the complex were studied through Debye model, from which the relaxation time for the dipoles (2.45 × 10−6 s) and the molecular dipole moment (3.63 × 10−30 C m ) were determined. 相似文献
999.
Ce0.6Zr0.35Y0.05O2和Pr0.6Zr0.35Y0.05O2催化剂表面上CO氧化和18O-16O交换反应的研究 总被引:5,自引:0,他引:5
测定了在Ce0.6Zr0.4O2,Ce0.6Zr0.35Y0.05O2,Pr0.6Zr0.4O2和Pr0.6Zr0.35Y0.05O2 (分别表示为CZ,CYZ,PZ和PYZ)样品表面上的CO氧化反应和18O-16O 同位素交换反应.结果表明: 在CZ和PZ系列固熔中掺杂Y3 离子可以改善晶格氧的迁移速度;PZ和PZY的晶格氧比CZ 和CZY 的晶格氧具有更高的氧化反应活性.其原因是将Y3 掺杂到Ce0.6Zr0.4O2 或Pr0.6Zr0.4O2晶格中,增加了样品的氧空位浓度,从而提高了晶格氧的迁移性质,而PrOx比CeO2具有更低温度的氧化还原性质,因此PZ和PZY的晶格氧比CZ 和CZY 的晶格氧具有更高的氧化反应活性. 相似文献
1000.
Merlin C. E. Bandeira Franci D. Prochnow Lúcia K. Noda Norberto S. Gonçalves Isolda Costa Hercílio G. de Melo Joe A. Crayston César V. Franco 《Journal of Solid State Electrochemistry》2004,8(4):244-251
The electropolymerization of trans-[RuCl2(vpy)4] (vpy=4-vinylpyridine) monomer on Nd-Fe-B magnets was studied by electrochemical impedance spectroscopy (EIS). Impedance diagrams obtained during the polymerization process were used to monitor film formation. The EIS results gave insight into the electrochemical phenomena occurring at the magnet surface as the polymerization process progressed. The film structure and morphology were also studied by X-ray photoelectron spectroscopy, scanning electron microscopy and Raman spectroscopy. The Raman spectroscopy results showed that the polymerization takes place at the vinyl groups of the monomer and also that the redox polymer structure is very similar to that of the monomer. The ratio of the intensity of the XPS peaks for fluorine (from the electrolyte PF6
–) and ruthenium present in the film showed that the polymer on Nd-Fe-B contained an equal proportion of Ru2+ and Ru3+, indicating that part of the film is positively charged, i.e. {[RuCl2(vpy)4]+}
n
. 相似文献