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211.
Mustafa Bulut Birsen Yilmaz Mehtap Yapici M. Vezir Kahraman 《Journal of inclusion phenomena and macrocyclic chemistry》1996,26(1-3):39-46
The presented ethylenedioxy compounds5a,5d,6a and6c are examples of novel cyclic ethers, while macrocyclic polyethers represent new crown ether analogues. New coumestan-crowns5a-f, derivatives of 6,7-dihydroxy-3,4-dihydro-2H-dibenzofuran-1-one and 6,7-dihydroxy-3,3-dimethyl-3,4-dihydro-2H-dibenzofuran-1-one6a-e were synthesized from the correspondingo-dihydroxy compounds3a-b,4a-b and ditosylates or dichlorides of di- or triethylene glycol in the presence of K2CO3, in DMF/H2O (15/1) solutions at 65–75 °C for 35 hours. The structure of the macrocyclic ethers obtained were confirmed by1H-NMR,13C-NMR, IR spectra and elemental analyses.Presented at the Sixth International Seminar on Inclusion Compounds, Istanbul, Turkey, 27–31 August, 1995. 相似文献
212.
In this study, a novel preconcentration/separation technique based on the slurry analysis of chromium loaded on mercaptoundecanoic acid modified TiO2 core-Au shell nanoparticles prior to its determination by electrothermal atomic absorption spectrometry was described. For this purpose, at first, TiO2 nanoparticles were coated with gold shell and then modified with mercaptoundecanoic acid (MUA). Cr (III) was collected on the prepared sorbent by conventional batch technique. After separation of liquid phase, slurry of the sorbent was prepared and directly introduced into graphite furnace of atomic absorption spectrometry. By this way, all drawbacks due to elution procedure were eliminated. Optimum conditions for quantitative sorption and preparation of the slurry were investigated. The chromium in certificated sea-water and spiked drinking water was recovered in the range of 95% confidence level. The proposed technique was fast and simple as well as the risks of contamination and loss during elution were low. The limit of detection (3σ, N = 10) was 0.34 μg L− 1. 相似文献
213.
?smail G?k O. Zeki Okuyucu Ferda? Kahraman H. Hilmi Hacisaliho?lu 《Advances in Applied Clifford Algebras》2011,21(4):707-719
In this paper we give a new definition of harmonic curvature functions in terms of B
2 and we define a new kind of slant helix which we call quaternionic B
2–slant helix in 4–dimensional Euclidean space E
4 by using the new harmonic curvature functions. Also we define a vector field D which we call Darboux quaternion of the real quaternionic B
2–slant helix in 4–dimensional Euclidean space E
4 and we give a new characterization such as:
"a: I ì \mathbb R ? E4{``\alpha : I \subset {\mathbb R} \rightarrow E^4} is a quaternionic B
2–slant helix ${\Leftrightarrow H^\prime_2 -KH_{1} = 0"}${\Leftrightarrow H^\prime_2 -KH_{1} = 0"} where H
2, H
1 are harmonic curvature functions and K is the principal curvature function of the curve α. 相似文献
214.
215.
H.M. Çakmak H.A. Çetinkara S. Kahraman F. Bayansal M. Tepe H.S. Güder M.A. Çipiloğlu 《Superlattices and Microstructures》2012
In order to investigate the effect of thermal oxidation temperature on tin dioxide (SnO2), tin dioxide films were obtained on quartz substrates by vacuum evaporation of tin metal. The films were characterized by X-ray diffraction (XRD) analyses, scanning electron microscopy (SEM), temperature dependent electrical resistivity measurement and optical absorption spectroscopy. The SEM images showed that the films are dense, continuous and are composed of nanoparticles and particle sizes are increased after thermal oxidation. From the X-ray measurement results, the films indicated two strong reflection peaks of tetragonal structure in the orientations of (1 0 1) and (2 0 0) at 2θ = 33.89° and 37.95°, respectively. Intensity of the peaks increased with increasing thermal oxidation temperature. We found resistivity values of about 10−4 Ω-cm. Optical absorption spectra of the films in the UV–Vis spectral range revealed that optical band gap (Eg) value of the films increases with increasing thermal oxidation temperature. 相似文献
216.
We construct an effective potential for the complex Langevin equation on a lattice. We show that the minimum of this effective potential gives the space–time and Langevin time average of the complex Langevin field. The loop expansion of the effective potential is matched with the derivative expansion of the associated Schwinger–Dyson equation to predict the stationary distribution to which the complex Langevin equation converges. 相似文献