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排序方式: 共有293条查询结果,搜索用时 31 毫秒
71.
M.A. Mastro S. Maximenko M. Gowda B.S. Simpkins P.E. Pehrsson J.P. Long A.J. Makinen J.A. Freitas Jr. J.K. Hite C.R. Eddy Jr. J. Kim 《Journal of Crystal Growth》2009,311(10):2982-2986
Photo- and cathodo-luminescence measurements of a variable-diameter ensemble of GaN nanowires revealed a diameter-dependent, spectral emission distribution between 350 nm and 850 nm. Spectral analysis indicated that wires with a diameter less than 400 nm were dominated by a yellow luminescence with a weaker near UV/violet emission also present. Examination of this ensemble showed that there was a general trend in the ratio of near-UV-to-yellow emission intensities with increasing nanowire diameter. Additionally, a broad green emission appears in the nanowires with a diameter above approximately 200 nm. A calculation based on the nanoheteroepitaxy model indicates that this diameter represents a transitional thickness where strain is relieved by defect formation mechanisms with a characteristic green emission. 相似文献
72.
Six new dioxobridged complexes of molybdenum (IV) and tungsten (IV) with N-alkylphenothiazines having the general formula
M2O4(L)2(H2O)2 [where M = molybdenum or tungsten and L = N-alkylphenothiazines] have been synthesised. The complexes have been characterised
on the basis of analytical, molar conductance, magnetic susceptibility, spectral data, TGA and DTA. The low magnetic moments
for the complexes are due to spin-spin interaction or metal-metal bonding. The interactions of these complexes with some biologically
important amino acids have been studied. 相似文献
73.
Y. T. Krishne Gowda P. A. Aswatha Narayana K. N. Seetharamu 《Heat and Mass Transfer》1996,31(5):347-352
Two dimensional unsteady Navier-Stokes and the energy equations are solved using finite element method for the case of flow past five row deep in-line bundle of circular cylinders with pitch to diameter ratios (PDR) of 1.5 and 2.0. Numerical solutions of governing equations have been obtained using Euler's explicit algorithm. Analysis have been made for Reynolds number of 100 and Prandtl number of 0.71. The effect of Richardson number (Ri=Gr/Re 2) on the flow and heat transfer have been investigated forRi=?1.0, ?0.5, 0.0, +0.5 and +1.0. Streamlines, isovorticity lines, pressure and temperature contours, local and average Nusselt numbers, pressure and shear stress distribution around the cylinders are presented. Results obtained for forced convection (Ri=0.0) agree well with the available experimental and numerical results. There is considerable effect of buoyancy over tube bundles both in buoyancy aiding and opposing flows. 相似文献
74.
M. Vishwas Sudhir Kumar Sharma K. Narasimha Rao S. Mohan K.V. Arjuna Gowda R.P.S. Chakradhar 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(3):1073-1077
Titanium dioxide thin films have been synthesized by sol–gel spin coating technique on glass and silicon substrates with and without surfactant polyethylene glycol (PEG). XRD and SEM results confirm the presence of nano-crystalline (anatase) phase at an annealing temperature of 300 °C. The influence of surfactant and annealing temperature on optical properties of TiO2 thin films has been studied. Optical constants and film thickness were estimated by Swanepoel's (envelope) method and by ellipsometric measurements in the visible spectral range. The optical transmittance and reflectance were found to decrease with an increase in PEG percentage. Refractive index of the films decreased and film thickness increased with the increase in percentage of surfactant. The refractive index of the un-doped TiO2 films was estimated at different annealing temperatures and it has increased with the increasing annealing temperature. The optical band gap of pure TiO2 films was estimated by Tauc's method at different annealing temperature. 相似文献
75.
Padmarajaiah Nagaraja Naef Ghllab S. Al-Tayar Anantharaman Shivakumar Ashwine K. Shrestha Avinash K. Gowda 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(5):1411-1416
A very simple, sensitive, fairly selective and rapid spectrophotometric method for the determination of trace amounts of nitrite has been described. This method is based on the diazotized intramolecular coupling of electrophilic diazonium cation with the phenolic group of 4-amino-5-hydroxynaphthalene-2,7-disulphonic acid monosodium salt (AHNDMS) in a phosphate buffer solution of pH 7.5. The cyclic product has a purple color with maximum absorbance at 560 nm and is stable for 6 h. Optimum reaction conditions and other important analytical parameters for the maximum color development were established. Beer's law was found to obey for nitrite in the concentration range of 0.1–1.6 μg ml?1 with molar absorptivity of 2.6 × 104 l mol?1 cm?1 and Sandell's sensitivity of 0.0075 μg ml?1. The effect of interfering ions on the determination is described. The recommended method was applied for the determination of nitrite in different water, soil and human saliva samples. The performance of the recommended method was evaluated in terms of Student's t-test and variance ratio F-test, which indicated the significance of proposed method over the reference method. 相似文献
76.
The behavior of 10 arylhalosulfonamides as oxidimetric analytical reagents toward thiosemicarbazide (TSC) alone or in its metal complexes has been critically examined and general procedures for its estimation have been developed. The proposed analytical techniques are simple and reproducible. These procedures are also useful for computing the number of TSC ligands present in the complexes. The oxidation involves twelve-electron change per TSC molecule with all the oxidants. The complexes have been prepared and characterized by elemental analyses and IR spectra. 相似文献
77.
Naphthidine, dimethylnaphthidine, dimethylnaphthidinedisulphonic acid, o-dianisidine, Quinoline Yellow, diphenylbenzidine and Amaranth are proposed as indicators in titrations of arsenic(III), iron(II), antimony(III), hydroquinone, hydrazinium sulphate, phenylhydrazine hydrochloride, semicarbazide hydrochloride and ascorbic acid with dichloramine-B. They give a very sharp colour change at the equivalence point. Arsenic(III) and iron(II) are suggested for standardization of dichloramine-B solutions. A potentiometric method for the determination of arsenic(III) and semicarbazide hydrochloride is described. 相似文献
78.
Polynuclear complexes of RHII and RHIII with fiveN-alkylphenothiazines as principal ligands have been prepared. The complexes were characterized by their elemental analyses,
molar conductivities, and spectral data. The molecular formulae of the new complexes are as follows: [Rh3(PTZ)2(OH2)2Cl8]Cl, where PTZ=chlorpromazine or promethazine; [Rh3(EP)2(OH2)2Cl8][Rh(OH2)2Cl4], where EP=ethopropazine; [Rh4(TF)2(OH2)5Cl9]Cl·H2O, where TF=trifluoperazine; and [Rh2(TC)3(OH2)Cl6]. H2O, where TC=2-chlorophenothiazine. A tentative structure for each of the complexes is proposed.
TMC 2627 相似文献
79.
Summary Five complexes of rhenium(VII) oxide with N-alkylphenothiazines have been synthesized and characterized on the basis of elemental analyses, molar conductances, and u.v.-vis., i.r. and n.m.r. spectral data. The molecular formulas of the new ionic complexes are: [ReO3(PTZ)2(H2O)][ReO4], PTZ = chlorpromazine, promethazine or ethopropazine; [ReO3(TF)(H2O)][ReO4], TF = trifluoperazine; and [ReO3(TR)3][ReO4(H2O)2]·H2O, TR = thioridazine. Tentative structures have been proposed. 相似文献
80.
Complexes of platinum(IV), ruthenium(III), rhodium(III), iridium(III), gold(III), dioxouranium(II), zinc(II), cadmium(II),
mercury(II) and manganese(II) with isonicotinic acid hydrazide were prepared and characterized on the basis of analytical,
conductometric, magnetic susceptibility and spectral data. Platinum(IV) ruthenium(III), rhodium(III), iridium(III), dioxouranium(II)
and manganese(II) form six-coordinate complexes while gold(III), zinc(II), cadmium(II) and mercury(II) form four coordinate
complexes. 相似文献