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11.
In 1951, Diliberto and Straus [5] proposed a levelling algorithm for the uniform approximation of a bivariate function, defined on a rectangle with sides parallel to the coordinate axes, by sums of univariate functions. In the current paper, we consider the problem of approximation of a continuous function defined on a compact Hausdorff space by a sum of two closed algebras containing constants. Under reasonable assumptions, we show the convergence of the Diliberto–Straus algorithm. For the approximation by sums of univariate functions, it follows that Diliberto–Straus’s original result holds for a large class of compact convex sets. 相似文献
12.
Yasuo Kuga Guifu Zhang Ji-Hae Yea Akira Ishimaru 《Waves in Random and Complex Media》1998,8(3):269-281
The analytical solution for the angular correlation function of scattered waves from randomly distributed infinitely long cylinders is obtained using the second-order approximation with a modified attenuation coefficient. The approach is based on the coherent summation of the scattered waves which preserves the interference effects such as backscattering enhancement. The modification of the transport attenuation coefficient includes the contribution due to the incoherent wave. By comparing with the exact numerical simulations, we found that the correction factor is given by (1-μ¯) which also appears in the diffusion equation. The present approach gives good agreement with numerical and experimental results. 相似文献
13.
R. Ködding W. Lamprecht H. P. Wolff J. Karl und KH. R. Koczorek 《Fresenius' Journal of Analytical Chemistry》1961,181(1):574-580
Ohne ZusammenfassungAuszug aus der Dissertation Reinhard Ködding, Technische Hochschule München 1961. 相似文献
14.
15.
报道了电子引起的钛、锰原子的K壳层电离截面实验值。实验中,采用了薄靶厚衬底技术,并将衬底中反射的电子对测量值的影响进行了修正。实验结果与其他文献报道的测量结果相吻合。最后,还将实验结果与Casnati等人的经验公式进行了比较。 相似文献
16.
Gui Rong Wang Yong Li Li Wei Dong Zhang Xian Wen Yang Wen Cong Liu Ji Ye Zhi Jun Zhu Hong Chen 《中国化学快报》2012,23(11):1251-1253
One new and 16 known compounds were isolated from Abies sibirica.Their structures were assigned mainly on the basis of NMR and MS spectroscopic data.In bioassay for anti-proliferative activity against four human tumor cells,compound 7 exhibited selective anti-proliferative activity against COLO-205 tumor cell with an IC50 value of 0.9μg/mL. 相似文献
17.
Shahnila SHAH Huma SHAKH Najma MEMON Muhammad Iqbal BHANGER Tahira QURESH Humaira KHAN Adil DENZL 《Turkish Journal of Chemistry》2020,44(4):901
Human body is greatly exposed to aluminum due to its high abundance in the environment. This nonessential metal is a threat to the patients of chronic renal disorders, as it is easily retained in their plasma and quickly accumulates in different tissues. Thus, there is great need to remove it from the aqueous environment. In this study, Al3+ imprinted semiinterpenetrating polymer network (semi-IPN)-based cryogel composite was prepared and applied for the purification of environmental and drinking water samples from aluminum. Poly (2-hydroxyethyl methacrylate) (pHEMA) discs were produced via cryogenic treatment and imprinted semi-IPN was introduced to the 3-(trimethoxysilyl) propyl acrylatemodified macroporous cryogel discs. The adsorption properties and selectivity of the aluminum (III) imprinted semi-IPN cryogel composite were studied in detail. The imprinted semi-IPN cryogel composite showed good selectivity towards aluminum (III) ions with the imprinting factor (IF) of 76.4 in the presence of competing copper (II), nickle (II), and iron (III) ions. The maximum adsorption capacity of 271 μmol g-1 was obtained for aluminum (III) at pH 7.0 within 10 min using imprinted semi-IPN cryogel composite. The good selectivity and reusability of aluminum (III)-imprinted semi-IPN cryogel composite makes this material an eligible candidate for the purification of drinking water from aluminum (III) leaving important minerals remained in the water. 相似文献
18.
An ion chromatography(IC) system coupled with on-line column-switching technique was used to determine anions ofμg/g levels in organic chemicals of analytical reagent grade.A novel polystyrene-divinylbenzene-carbon nanotube(PS-DVB-CNT) stationary phase was utilized for matrix elimination.A calibration study was conducted by preparing and analyzing eight concentrations(between 10 and 5000μg/L) of eight standards in deionized water.The linearity was between 0.9978 and 1.And the detection limits ranged from 1.54μg/L to 10.02μg/L.A spiking study was performed on two representative organic chemicals.The recoveries were between 84.3%and 119.6%. 相似文献
19.
Yea‐Yang Su Chun‐Che Shih Lung‐Ching Chen Chun‐Ming Shih Shing‐Jong Lin 《Surface and interface analysis : SIA》2010,42(2):59-65
Wallstent has been successfully used to open up clogged peripheral arteries. Co? Cr alloy is the preferred metal for the construction of wallstent. Unfortunately, major complications such as in‐stent intimal hyperplasia,stent obstruction, and stent stricture are often reported, and these complications could be related to the metallic properties of the wallstent. In this study, the electrochemical properties of Co? Cr wires from wallstent were investigated using cyclic polarization, open‐circuit potential, potentiostatic condition, and electrochemical impedance spectroscopy. Scanning electron microscopy and X‐ray mapping were also employed to investigate the surface morphology and elemental distribution after electrochemical measurement. Results of this study showed the heterogeneous electrochemical properties of Co? Cr alloy wires that could result in severe galvanic corrosion of wallstent after implantation. Severe corrosion process could cause fracture of wallstent, resulting in localized inflammation, allergy, and thicker neointima. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
20.
Synthesis and biological evaluation of various tricyclic and tetracyclic indoles are described. A number of these compounds possess in vitro activity against human nasopharyngeal carcinoma (HONE‐1) and gastric adenocarcinoma (NUGC‐3) cell lines. 相似文献