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排序方式: 共有379条查询结果,搜索用时 31 毫秒
41.
John Monaghan Mehmet Fatih Ozmantar 《International Journal of Computers for Mathematical Learning》2006,11(3):351-360
We comment on the paper The co-emergence of machine techniques, paper-and-pencil techniques, and theoretical reflection: A
study of CAS use in secondary school algebra by Carolyn Kieran and Paul Drijvers. We look at aspects of Kieran and Drijvers'
analysis with regard to ‚task-technique-theory’ in the light of a model of abstraction in context and suggest that this re-viewing
brings mutual analytic benefits. 相似文献
42.
Esin ?spir Mükerrem Kurto?lu Fatih Purta? Selahattin Serin 《Transition Metal Chemistry》2005,30(8):1042-1047
Two new Schiff base ligands containing −SiOCH3 or −SiOCH2CH3 groups, 4-{[(3-trimethoxysilanepropyl)imino]methyl}benzene-1,3-diol (1) Hmsb and 4-{[(3-triethoxysilanepropyl)imino]methyl}benzene-1,3-diol
(5) Hesb, have been synthesized by the reaction of 2,4-dihydroxybenzaldehyde with 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane.
Six new transition metal [CuII, NiII and CoII complexes of these Schiff Base ligands were prepared. The complexes are formed by coordination of N, O atoms of the ligands. Their structures were confirmed by elemental analyses, 1H nmr, i.r. and u.v.–vis. spectral data. The analytical data shows that the metal-to-ligand ratio in the Schiff Base complexes
contains silane in 1:2. In addition, the antimicrobial activity of (1) Hmsb and (5) Hesb Schiff ligands, and their [M(msb)2] and [M(esb)2] type coordination compounds, were investigated 相似文献
43.
Fatih Özkaynak 《Physics letters. A》2010,374(36):3733-3738
It is important to design cryptographically strong S-Boxes in order to design secure systems. In this study, a strong, chaos-based S-Box design is proposed. Continuous-time Lorenz system is chosen as the chaotic system. Proposed methodology is analyzed and tested for the following criteria: Bijective property, nonlinearity, strict avalanche criterion, output bits independence criterion and equiprobable input/output XOR distribution. The results of the analysis show that the proposed cryptosystem is a highly reliable system suitable for secure communication. 相似文献
44.
Dilek Cam Kemal Keseroglu Mehmet Kahraman Fikrettin Sahin Mustafa Culha 《Journal of Raman spectroscopy : JRS》2010,41(5):484-489
Surface‐enhanced Raman scattering (SERS) is a technique capable of identifying each component in a mixture because of its intrinsically narrow spectral bands. In a clinical setting, the identification of bacteria from its initial culture by collecting the colonies on the culture plate significantly decreases the analysis time and the cost. The identification of bacteria from their mixtures is attempted using SERS. A simple mixing procedure of bacterial samples and concentrated colloidal suspension is proven to be mostly satisfactory for the generation of the reproducible SERS spectra that can be used for bacterial identification. The mixture of three different but related bacterial species Shigella sonnei, Proteus vulgaris, and Erwinia amylovara and three Escherichia coli strains (BFK13, BHK7, DH5 α) are used as model systems to test the feasibility of the approach. The results indicate that it is possible to identify the composition of a bacterial mixture. This approach can easily be utilized for the bacteria originating from the same source with similar growth profiles. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
45.
A self-adaptive global best harmony search algorithm for continuous optimization problems 总被引:3,自引:0,他引:3
This paper presents a self-adaptive global best harmony search (SGHS) algorithm for solving continuous optimization problems. In the proposed SGHS algorithm, a new improvisation scheme is developed so that the good information captured in the current global best solution can be well utilized to generate new harmonies. The harmony memory consideration rate (HMCR) and pitch adjustment rate (PAR) are dynamically adapted by the learning mechanisms proposed. The distance bandwidth (BW) is dynamically adjusted to favor exploration in the early stages and exploitation during the final stages of the search process. Extensive computational simulations and comparisons are carried out by employing a set of 16 benchmark problems from literature. The computational results show that the proposed SGHS algorithm is more effective in finding better solutions than the state-of-the-art harmony search (HS) variants. 相似文献
46.
In this study, we have investigated the effect of the buffer layers on the electronic and optical properties of an exciton (X) and a biexciton (XX) in a type-II CdTe/CdSe quantum dot nanocrystal. In an experimental study, it has been reported that when a CdTe/CdSe quantum dot nanocrystal is coated by a ZnTe material as a buffer layer, the photoluminescence quantum yield is growing from 4 to 20%. We have confirmed theoretically this improvement and extended the calculations to an XX structure. In the calculations, two different semiconductor materials, CdS and ZnTe, have been considered for the buffer layer. We have theoretically shown that the buffer layer causes an increase in the radiative oscillator strength of both X and XX. When the ZnTe is used as the buffer layer, the oscillator strength becomes stronger when compared to CdSe buffer material because of higher conduction band offset between CdSe and ZnTe. 相似文献
47.
Uğur Parlatan Günay Başar Nima Bavili Harika Yumru Fatih Sag Sibel Bulgurcuoglu 《光谱学快报》2013,46(7):458-463
ABSTRACTEmbryo viability quantification is an important topic for in vitro fertilization researchers. This study suggests Raman spectroscopy as a candidate method to find an objective measure of embryo viability. Raman spectra of 31 spent embryo culture samples (16 nonpregnant, 15 pregnant) from 31 patients were analyzed with band component analysis. The band area ratio of 902 to 943 cm?1 was found to be the most discriminatory. These bands are related to glutamine, glycine, proline, aspartic acid, and valine. According to the pregnancy outcome the sensitivity and specificity of Raman analysis were found to be 93% and 77%, respectively. 相似文献
48.
Ion chromatography–inductively coupled plasma-mass spectrometry (IC–ICP-MS) was used for the identification and quantification of chromium species. Chromium(III) and chromium(VI) were separated and determined by IC–ICP-MS. The separation was achieved using an anion exchange column with 0.55?M HNO3 as mobile phase. It was a particular goal of this work to exclusively use nitric acid for elution in order to reduce interferences in the ICP-MS system. Analytical figures of merit were calculated under the optimum conditions by developing calibration plots in a concentration range of 0.50–250?µg/L for both species. The detection limits for Cr(III) and Cr(VI) were 0.09 and 0.03?µg/L, respectively. Spiked recovery tests were used to evaluate the applicability of the analytical method in environmental samples, and the recoveries ranged between 97 and 103% for both analytes. The accuracy of the method for total chromium content was validated through the analysis of a spring water-certified reference material (UME 1201), and the obtained results were in good agreement with the certified value. Lettuce seedlings were cultivated to evaluate the intake levels of these species. In addition, the bioaccessibility of Cr(III) and Cr(VI) from the lettuce seedlings in simulated gastric and intestinal fluids media was examined. 相似文献
49.
Selimefendigil Fatih Oztop Hakan F. Chamkha Ali J. 《Journal of Thermal Analysis and Calorimetry》2019,135(1):325-340
Journal of Thermal Analysis and Calorimetry - In this study, fluid flow and heat transfer in a vertical lid-driven CuO–water nanofluid filled square cavity with a flexible fin attached to its... 相似文献
50.
Control of four-wave mixing phase-matching condition using the Brillouin slow-light effect in fibers
All-optical control of the phase-matching condition in four-wave mixing (FWM) processes is demonstrated using the Brillouin slow-light effect in optical fibers. A counterpropagating stimulated Brillouin scattering (SBS) pump has been used to control the phase velocity of the FWM pump in a wavelength conversion scheme. Both experimental results and theoretical simulations show an SBS-controlled 20 dB difference on the wavelength conversion efficiency. 相似文献