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141.
A. V. Garbar M. R. Leonov L. N. Zakharov Yu. T. Struchkov 《Russian Chemical Bulletin》1996,45(2):451-454
A new neutral -arene complex of trivalent uranium, (6-C6H5Me)U(AlCl4)3 (1), was obtained by the reductive Freidel-Crafts reaction. The crystal structure of 1 was determined by single crystal X-ray diffraction analysis. The U atom in 1 is bound to the C6H5Me group by the 6 mechanism and is linked to the three AICl4 groups through two g-CI bridges. The coordination of the U atom is a distorted pentagonal bipyramid in which the center of the arene ring is in one apical position, and the bridging Cl atoms occupy the other vertices.Translated from Izvestiva Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 469–472, February, 1996. 相似文献
142.
钌—钛金属氧化物涂层电极的电子能谱分析 总被引:1,自引:0,他引:1
用X-光电子能谱分析了Ru-Ti金属氧化物电极的组成、结构和元素价态。结果表明,电极表面不同于体内,讨论了表面和体内Ti的价态区别对Ru-Ti阳极活性和寿命的影响,指出掺杂Ir和Pd后会提高电极活性。 相似文献
143.
Ling YI Ping LI Zhi Ming BI 《中国化学快报》2006,17(12):1579-1581
Angelica sinensis (Oliv.) Diels (Umbelliferae), known as Danggui in Chinese, one of the most important traditional Chinese medicines, is used for tonifying blood and treating female irregular menstruation and amenorrhoea. It is also used for treatment of … 相似文献
144.
A. Hamou C Devallencourt F. Burel J. M. Saiter M. Belbachir 《Journal of Thermal Analysis and Calorimetry》1998,52(3):697-703
The thermal stability of p-cresol novolac resin was studied by means of DSC, X-ray diffraction, thermogravimetry and SEC investigations.
After 30 thermal cycles in which the same sample was heated, cooled and heated again, without attainment of the temperature
of degradation at any time in the experiment, important structural modifications are observed. At the end of the experiments,
the resin, which is initially highly crystalline, exhibits all the characteristics of a semi-crystalline material.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
145.
类立方烷型金属原子簇化合物M_4E_4(M为过渡金属,E为硫属元素)的研究长期以来受到重视,其主要原因有二:(1)一些类立方烷型金属原子簇(如Fe_4S_4及Fe-Mo-S原子簇)在生物体系(如固氮酶、铁氧还蛋白)中有重要意义;(2)由于可以方便地对M或E作系列性的改变,因而M_4E_4成为研究原子簇化合物的电子结构及检测各种有关的理论假设的重要模型化合物。 相似文献
146.
Magnetic Interactions in Ternary Cobalt Chalcogenides containing Isolated Tetrahedral Cobalt Anionic Groups. The Spin Structures of Na6CoS4 and Na6CoSe4 The sodium cobalt chalcogenides Na6CoS4 and Na6CoSe4 are characterized by isolated [CoX4]-units. Despite the large distances of more than 6 Å between the cobalt ions magnetic inter-actions at low temperatures lead to threedimensionally ordered spin structures, that were determined from neutron diffraction experiments. The magnetic structure can be described in the Shubnicov group P2abc21 with a unit cell that is four times as large as the crystallographic cell. The magnetic moments of both compounds correspond to the value expected for three unpaired electrons per Co2+ ion. 相似文献
147.
Wolfgang Schattke 《Progress in Surface Science》1997,54(3-4):211-227
Photoemission in the vacuum ultraviolet photon regime has proved to be an effective tool for the investigation of valence band surface electronic structure. The interpretation cannot be exclusively confined to the valence bands but has to consider cross sections with realistic final states consistently designed within the one-step model. Therefore especially in the surface sensitive photoemission, several effects hide the final goal of deducing the energetic and wavefunction structure together with microscopic potential parameters through a convincing agreement of calculated with measured spectra. The final states band structure is much less well understood than the valence band structure under consideration. The optical potential, which controls the surface sensitivity through the underlying damping mechanisms, widely relies on empirical assumptions. Furthermore, the photon field is not only strongly influenced but in the vicinity of the plasma frequency also deteriorated by the electronic response. In view of high resolution spectroscopy the accuracy of the data interpretation is affected, and in fact, band-mapping methods are no longer valid. Examples of recent calculations to account for these effects are reviewed. 相似文献
148.
Gololobov Yu. G. Galkina M. A. Dovgan O. V. Krasnova I. Yu. Petrovskii P. V. Antipin M. Yu. Voronzov I. I. Lyssenko K. A. Schmutzler R. 《Russian Chemical Bulletin》2001,50(2):279-286
The reactions of the zwitterion derived from triisopropylphosphine and ethyl 2-cyanoacrylate with mercuric chloride and aryl isothiocyanates containing Cl atoms in the ortho positions of the benzene ring follow an unusual pathway because this zwitterion represents latent triisopropylphosphine due to the reversibility of the reaction of triisopropylphosphine with ethyl 2-cyanoacrylate. The molecular structures of the adducts of triisopropylphosphine with 2,6-dichloro- and 2,4,6-trichlorophenyl isothiocyanates were confirmed by X-ray diffraction study. Protonation of the adduct of triisopropylphosphine with 2,6-dichlorophenyl isothiocyanate occurred at the nitrogen atom, whereas methylation with methyl trifluoromethanesulfonate afforded an S-methylation product. The results of X-ray diffraction study of the resulting compounds are presented. 相似文献
149.
Teresa Borowiak Maciej Kubicki Grzegorz Dutkiewicz Marek Pietraszkiewicz Oksana Pietraszkiewicz 《Journal of inclusion phenomena and macrocyclic chemistry》2005,51(3-4):181-189
Two newly identified supramolecular structures arise from self-assembly of the macrocyclic 1,5,9,18,22,26- hexaaza[11.11]-p-cyclophane salts with o-nitrophenol (C28H50N6)4+·4(C6H4NO2O)− (1) and with HCl (C28H52N6)6+·6Cl-·4H2O (2). In both cases two-dimensional supramolecular sheets are formed. 相似文献
150.
Effect of molecular orientation distribution and crystallinity on the measurement of the crystal lattice modulus of nylon 6 by x-ray diffraction 总被引:1,自引:0,他引:1
The crystal lattice modulus of nylon 6 (-type) was measured by x-ray diffraction using nylon 6 films drawn up to five times. The measured crystal lattice modulus was 173–175 GPa for all specimens whose crystallinity and the Young's modulus were beyond 46% and 3.75 GPa, respectively. These results indicate that a state of homogenous stress can be achieved. In contrast, the values were scattered for the speciments whose crystallinity and Young's modulus are less than the above values. To study the origin, a numerical calculation of the crystal lattice modulus, as measured by x-ray diffraction, was carried out by considering effects on the orientation factors of molecular chains and crystallinity. In this calculation, a previously introduced model was employed, in which oriented crystalline layers are surrounded by oriented amorphous phases so that the strains of the two phases at the boundary are identical. The theoretical results calculated by the introduced model indicated that the crystal lattice modulus by x-ray diffraction is almost equal to the intrinsic crystal modulus if the morphology of the test specimen can be represented as a series model. In contrast, if a parallel model is more appropriate, the difference between the measured modulus and the intrinsic value can be pronounced. Such morphological dependence was found to be less pronounced with increasing high degree of molecular orientation and crystallinity. 相似文献