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991.
Frank M. Liang 《Discrete Mathematics》1979,28(3):325-326
We give a simple proof of the 3d distance conjecture. 相似文献
992.
993.
L.T. Yang J.K. Liang G.B. Song J. Luo F.S. Liu H.F. Yang G.H. Rao 《Applied Physics A: Materials Science & Processing》2005,80(4):865-870
The compound FeSr2NdCu2O7+ (Fe1212) was successfully synthesized by solid-state reaction. X-ray diffraction data indicate that the sample is of single phase. Rietveld whole-pattern-fitting method was used to refine the crystal structure of samples prepared under different annealing conditions using the tetragonal system with space group P4/mmm. Magnetization measurements indicate that magnetic susceptibility changes with temperature in a Curie-type manner. Resistance measurements indicate that these samples have a semiconductor-like behavior. PACS 61.10.Nz; 74.72.Jt 相似文献
994.
Y.?HaoEmail author J.-Q.?Liang Y.?Zhang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,36(1):33-39
The low-energy-level macroscopic wave functions of the Bose-Einstein
condensate (BEC) trapped in a symmetric double-well and a periodic potential
are obtained by solving the Gross-Pitaevskii equation numerically. The
ground state tunnel splitting is evaluated in terms of the even and odd wave
functions corresponding to the global ground and excited states
respectively. We show that the numerical result is in good agreement with
the analytic level splitting obtained by means of the periodic instanton
method. 相似文献
995.
The palladium-catalyzed aryl amination of 1-bromo-2-fluorobenzene with N,N-dimethylethylenediamine quantitatively produces N-(dimethylaminoethyl)-2-fluoroaniline, which subsequently reacts with KPPh2 in 1,4-dioxane to afford N-(dimethylaminoethyl)-2-diphenylphosphinoaniline (H[PNN]). The reactions of trialkylaluminium with H[PNN] in toluene generate the corresponding aluminium dialkyl complexes [PNN]AlR2 (R = Me, Et, i-Bu). The solution NMR spectroscopic and X-ray crystallographic studies are indicative of a trigonal bipyramidal geometry for these aluminium complexes in which the amino nitrogen atom is trans to the phosphorus donor of the [PNN]- ligand. This study presents rare examples of structurally characterized, five-coordinate aluminium hydrocarbyl complexes supported by phosphine-derived ligands. 相似文献
996.
Liu Z Xu D Liang J Shen J Zhang S Qian Y 《The journal of physical chemistry. B》2005,109(21):10699-10704
We demonstrate a facile solution-phase method for the synthesis of single-crystal, high aspect ratio, and ultrathin nanowires of hexagonal-phase Cu2S by thermal decomposition of CuS2CNEt2 in a mixed surfactant solvent of dodecanethiol and oleic acid at 160 degrees C. Cu2S nanowires can be controllably synthesized with a diameter as thin as 1.7 nm and length up to tens of micrometers; they are usually aligned in the form of bundles with a thickness of hundreds of nanometers. Based on the experimental results, the formation mechanism of the ultrathin nanowires has been properly proposed. Some key synthetic parameters, which have a significant effect on the sizes and shapes of the products, have also been investigated in detail. UV-vis spectroscopy measurement reveals that the resultant ultrathin nanowires show a strong quantum size effect. 相似文献
997.
Chattopadhyay J Sadana AK Liang F Beach JM Xiao Y Hauge RH Billups WE 《Organic letters》2005,7(19):4067-4069
[reaction: see text] Carbon nanotube salts prepared by treating single-wall carbon nanotubes (SWNTs) with lithium in liquid ammonia react readily with aryl iodides to give SWNTs functionalized by aryl groups. 相似文献
998.
For the purpose of investigating the tautomerism from glycinamide (G) to glycinamidic acid (G*) induced by proton transfer, we carried out a study of structural interconversion of the two tautomers and the relative stabilizing influences of water during the tautomerization process. Throughout the study, we used density functional theory (DFT) calculations at the B3LYP/6-311++G** level of theory, also considering the correction functions, that is, the effect of basis set superposition error (BSSE). Totally, 42 geometries, including fourteen important transition states, were optimized, and their geometric parameters have also been discussed in detail. Water molecules were gradually put in three different regions in the vicinity of G and its tautomer G*. The calculation results indicate that water in two of these regions can protect G from tautomerizing to G*, while in another region, water can assist in the tautomerism; this reveals that water molecules have stabilization and mutagenicity effects for G simultaneously. 相似文献
999.
Doughnut-shaped ZnO microparticles have been grown through a hydrothermal reaction in citrate solution at 120 degrees C. FESEM reveals that these microparticles consist of regular arranged nanoplates, and there is a concave on the surface of each microparticle. The existence of citrate is vital to the formation of the complex microparticles. Room temperature photoluminescence measurements show strong UV band emission. The yellow and green emissions related to the structure defects can be barely observed, indicating the high crystalline perfection of these microparticles. 相似文献
1000.
Sutherland M Li SY Hawthorn DG Hill RW Ronning F Tanatar MA Paglione J Zhang H Taillefer L DeBenedictis J Liang R Bonn DA Hardy WN 《Physical review letters》2005,94(14):147004
Low-temperature heat transport was used to investigate the ground state of high-purity single crystals of the lightly doped cuprate YBa2Cu3O6.33. Samples were measured with doping concentrations on either side of the superconducting phase boundary. We report the observation of delocalized fermionic excitations at zero energy in the nonsuperconducting state, which shows that the ground state of underdoped cuprates is a thermal metal. Its low-energy spectrum appears to be similar to that of the d-wave superconductor, i.e., nodal. The insulating ground state observed in underdoped La2-xSrxCuO4 is attributed to the competing spin-density-wave order. 相似文献