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排序方式: 共有517条查询结果,搜索用时 15 毫秒
41.
Anwar M Bailey JH Dickinson LC Edwards HJ Goswami R Moloney MG 《Organic & biomolecular chemistry》2003,1(13):2364-2376
Alkylation reactions using alpha-halolactams or lactam enolates derived from bicyclic lactam templates can proceed with high endo- or exo- diastereoselectivity respectively. In the latter case, stereochemical correction by means of enolate generation and hindered phenol quench is possible with moderate efficiency. This protocol has been applied to the synthesis of protected penmacric acid and its analogues. 相似文献
42.
Oxidative cyclization of 5α-cholestan-6-one thiosemicarbazone (1), its 3β-chloro (2) and 3β-acetoxy (3) analogues with active manganese dioxide at room temperature afforded selectively the corresponding (6R)-spiro-1’,2’,4’-triazoline-3’-thiones 4—6. This synthesis has the advantages of mild reaction conditions, easy handling, easily available reagent and high yields. The products have been characterized by analytical and spectral data. 相似文献
43.
Soluble in organic solvent polyaniline (PANI) was prepared using DBSA as a functional dopant. Miscibility was maximized for
PMMA with hydroquinone. Transmission electron micrographs showed lowest level of phase separation. Thermal studies by differential
scanning calorimetry show some peak shifts which indicate the miscibility of two polymers. The formations of new bonds are
also confirmed by Fourier transformation infrared spectroscopy. Electroconductivity increased with increase of content of
doped PAN1, showing percolation threshold at 3 wt %. 相似文献
44.
Anwar Usman Ibrahim Abdul Razak Suchada Chantrapromma Hoong-Kun Fun Jayanta Kumar Ray Sujit Das Adhikari Bishnu Pada Datta 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(12):1441-1442
In the title compound, C20H20FNO5S, the pyrrolidine ring adopts an envelope conformation. The fluorophenyl and thiophene rings are individually planar. The molecular and crystal structures are stabilized by intra- and intermolecular C—H⋯O interactions. 相似文献
45.
The densities (ρ), viscosities (η), refractive indices (nD), and speeds of sound (u), of binary mixtures of pyridine with 1-hexanol, 1-heptanol, 1-octanol and 1-decanol, including those of pure liquids, were measured over the entire composition range at 303.15 K and atmospheric pressure. From these experimental data, the values of excess molar volumes (VE), deviations in isentropic compressibilities (Δks), viscosities (Δh), molar refractions (ΔRm), apparent and partial molar volumes (Vf,2 and ), apparent and partial molar compressibilities (Kf,2 and ), of alkanols in pyridine and their corresponding deviations (ΔV and ΔK) were calculated. The variations of these parameters with composition of the mixtures suggest that the strength of interactions in these mixtures follow the order: 1-hexanol>1-heptanol>1-octanol>1-decanol. All the excess and deviation functions were fitted to Redlich-Kister polynomial equation to determine the fitting coefficients and the standard deviations. 相似文献
46.
The structure of the 2-thiazolylazosalicylic acid molecule, TAS, has been determined by means of quantum SCF-CI calculations. The ionization potential and the electron affinity of TAS molecule were calculated to have the values 9.057 and 2.56 eV respectively. The solvation energies in different solvents, and the bond orders of the TAS molecule were calculated for the neutral state, the oxidized form (the cation) and the reduced form (the anion). Mixed solvent studies were carried out with TAS and 2-benzothiazolylazosalicylic acid (BTAS), using polar solvents (EtOH and MeOH) to confirm the formation of a solvent-solute complex. The azo group in the TAS molecule nas a considerable contribution in the SCFLUMO; thus cathodic reduction has been focused on the azo group and was verified experimentally by cathodic reduction. 相似文献
47.
48.
S. Ahmad T. Rüffer H. Lang S. Nadeem S. A. Tirmizi M. Saleem A. Anwar 《Russian Journal of Coordination Chemistry》2010,36(7):520-524
The palladium(II) complex, [Pd(PPh3)2(Imt)2]Cl2 · 3.5H2O (I) (Imt = imidazolidine-2-thione), has been synthesized and characterized by IR, NMR, and X-ray crystallography. An upfield
shift in the >C=S resonance of Imt in the 13C NMR spectrum and a downfield shift in the N-H resonance in 1H NMR are consistent with the sulfur coordination of Imt to palladium(II). In the crystal structure of I, the central palladium atom is coordinated to two thione sulfur atoms of Imt and to two phosphorus atoms possessing a square-planar
environment with the average cis and trans bond angles of 89.60° and 167.31°, respectively. The title complex was screened for antimicrobial effects, and the results
showed that it exhibits moderate activities against gram-negative bacteria (E. coli, P. aeruginosa). The complexes also exhibited significant activities against yeast (C. albicans, S. serevisaiae). 相似文献
49.
María Sonsiré López Cadenas Anwar Hasmy Hebe Vessuri 《Journal of nanoparticle research》2011,13(8):3101-3106
Nanoscale research in Venezuela is briefly reviewed, with emphasis on research groups, research lines, and institutions involved.
A summary exploration is made of international collaboration through scientific co-authorship, as well of the efforts to build
nano capacities, available infrastructure, relationships to the productive sector and a weak presence in Venezuelan public
policies, although there is some expectation that the situation may soon begin to change. 相似文献
50.
Anwar Latif M. Khaleeq-ur-RahmanM.S. Rafique K.A. Bhatti 《Physica B: Condensed Matter》2011,406(9):1713-1716
The microstructural morphological changes in laser irradiated targets are investigated. Nd:YAG laser (1064 nm, ∼12 ns nominal, 1.1 MW) is used to irradiate 4 N pure (99.99%) fine polished and annealed silver samples in ambient air and under vacuum ∼10−6 Torr. The laser spot size and power density at tight focus are 12 μm and 3×1011 W/cm2, respectively. SEM micrographs and X-ray diffractograms of the exposed and unexposed targets reveal the surface texture and structural changes, respectively. Amongst the ablation mechanisms involved, exfoliation and hydrodynamic sputtering are found to be dominant. Surface modifications appear in the form of craters and ripples formation. Heat is conducted non-uniformly through narrow channels at the surface. Thermal stresses induced by the laser do not disturb inter planar distance of the target. On the other hand irradiation causes significant variations in grain size and diffracted X-rays intensities. 相似文献