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排序方式: 共有313条查询结果,搜索用时 31 毫秒
81.
Birthe V. Nielsen Thomas G. Nevell Eugen Barbu Gareth D. Rees John Tsibouklis 《Journal of Thermal Analysis and Calorimetry》2010,102(1):121-126
A thermogravimetric (TG) method is described for evaluating the substantivity of multi-functional polymeric materials that
may be used as protective coatings for teeth. Applied to poly(butyl methacrylate) and poly(octadecyl methacrylate) film structures
deposited onto model tooth surfaces from aqueous latex formulations, the method shows that while the latter polymer exhibits
little substantivity, the former may be a suitable candidate material for dental-care applications. 相似文献
82.
In this paper we prove the internal feedback stabilization of steady-state solutions of semilinear parabolic equations and introduce a controller synthesis methodology based on finite element approximations of the original PDEs. Numerical tests are given for some one- and two-dimensional nonlinear parabolic equations. 相似文献
83.
Moggio L De Napoli L Di Blasio B Di Fabio G D'Onofrio J Montesarchio D Messere A 《Organic letters》2006,8(10):2015-2018
[structure: see text] A new and versatile on-line automated solid-phase approach to obtain cyclic PNA (I and III) and cyclic PNA-DNA chimeras (II) in highly pure form has been developed. Starting from a Tentagel matrix functionalized with a 3-chloro-4-hydroxyphenylacetic linker, the synthesis of representative, new cyclic molecules by standard peptide and phosphoramidite-based chemistry has been achieved. 相似文献
84.
Giovanna Loredana La Torre Marcello SaittaAngela Giorgia Potortì Giuseppa Di BellaGiacomo Dugo 《Journal of chromatography. A》2010,1217(32):5215-5224
In the present study we report on the optimization and validation of a sensitive high performance liquid chromatography atmospheric pressure chemical ionization mass spectrometry (HPLC–APCI–MS) method for the determination of 8 bioactive amines (histamine, tyramine, tryptamine, 2-phenylethylamine, cadaverine, putrescine, spermidine and spermine) in donkey milk samples. The method involves donkey milk pre-treatment to remove proteins and pre-column dansylation of the amines. HPLC in reversed phase mode has been used for bioactive amines separation and the operating condition of the APCI–MS system proved to be powerful and very efficient for peak assignment. The separation was accomplished in a short time with an excellent resolution for all the amine peaks. Quantification was carried out by monitoring the characteristic [M+H]+ ion of each amine derivative. The method sensitivity, linearity and repeatability were assayed with satisfactory results. The detection limits of the analysed amines ranged from 0.5 μg L−1 to 15 μg L−1; the highest LOD was for spermine. Also remarkably good recovery values were obtained; at the lowest spiking level (1 μg L−1) the percent mean recoveries ranged from 77.7 to 109.7. Furthermore, as the investigations relate to a complex matrix as donkey milk, suitable studies on matrix effect were performed. Finally, the developed and validated method was applied to analyse 13 donkey milk samples. Among the identified bioactive amines, putrescine, spermine and spermidine proved to be the main amines in donkey milk. Their concentration levels in the present study were lower than the values determined in mature human, cow and sow milk. 相似文献
85.
86.
Approximations to mild solutions of stochastic semilinear equations with non-Lipschitz coefficients 总被引:3,自引:0,他引:3
In the present paper, using a Picard Type method of approximation, we investigate the global existence of mild solutions for a class of Ito Type stochastic differential equations whose coefficients satisfy conditions more general than the Lipschitz and linear growth ones. 相似文献
87.
Elisabetta Princi Silvia Vicini Enrico Pedemonte Noemi Proietti Donatella Capitani Anna Laura Segre Loredana D'Orazio Gennaro Gentile Carmen Polcaro Ezio Martuscelli 《Macromolecular Symposia》2004,218(1):343-352
Conversion of dihydroxyl groups to dialdehyde by periodate oxidation is a useful method widely used in derivatization of cellulose to activate the polymer to further reactions as grafting polymerization. To investigate the cellulose behavior at different level of oxidation and to better understand the influence of the crystallinity on the effects induced by oxidative reactions on different cellulose materials, linen and cotton textiles have been oxidized with periodate solutions in different conditions. Oxidized cellulose samples have been characterized by several techniques: solid-state 13C NMR, Wide Angle X-Ray diffraction, and SEM. Moreover the mechanical properties of the untreated and oxidized yarns have been evaluated by means of tensile tests, the oxidation degree has been measured by means of the hydroxylamine hydrochloride method. 相似文献
88.
89.
Loredana Coluccio Alfredo EisinbergGiuseppe Fedele 《Journal of Computational and Applied Mathematics》2008
The aim of this paper is to transform a polynomial expressed as a weighted sum of discrete orthogonal polynomials on Gauss–Lobatto nodes into Bernstein form and vice versa. Explicit formulas and recursion expressions are derived. Moreover, an efficient algorithm for the transformation from Gauss–Lobatto to Bernstein is proposed. Finally, in order to show the robustness of the proposed algorithm, experimental results are reported. 相似文献
90.
We prove the existence of a solution for the obstacle problem associated with the Kolmogorov operator corresponding to the stopping-time problem for stochastic Navier–Stokes equations in 2-D. 相似文献