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331.
导数分光光度—阻尼因子矩阵法同时测定三元混合组分 总被引:1,自引:0,他引:1
本文提出导数分光光度阻尼因子矩阵法同时测定带有辅料或其它呈一次或二次曲线干扰吸收的多元混合组分的基本原理和实验方法。以同时测定止喘咳糖浆中盐酸苯海拉明,盐酸麻黄碱,咳必清为例,研究了方法的可靠性和测量的适宜条件。结果满意。 相似文献
332.
Several N‐arylpiperazine phosphoramide analogues of chrysin are synthesized through a facile phosphorylated reaction for the first time. Their structures are elucidated by NMR, ESI MS, IR and Element analysis. The results showed that the phosphorylation action occurred regioselectively only at the hydroxyl group of 7 position of chrysin. 相似文献
333.
The regularity of functions from reproducing kernel Hilbert spaces (RKHSs) is studied in the setting of learning theory. We provide a reproducing property for partial derivatives up to order s when the Mercer kernel is C2s. For such a kernel on a general domain we show that the RKHS can be embedded into the function space Cs. These observations yield a representer theorem for regularized learning algorithms involving data for function values and gradients. Examples of Hermite learning and semi-supervised learning penalized by gradients on data are considered. 相似文献
334.
335.
Alicia Cordero José L. Hueso Eulalia Martínez Juan R. Torregrosa 《Journal of Computational and Applied Mathematics》2012
In the present paper, by approximating the derivatives in the well known fourth-order Ostrowski’s method and in a sixth-order improved Ostrowski’s method by central-difference quotients, we obtain new modifications of these methods free from derivatives. We prove the important fact that the methods obtained preserve their convergence orders 4 and 6, respectively, without calculating any derivatives. Finally, numerical tests confirm the theoretical results and allow us to compare these variants with the corresponding methods that make use of derivatives and with the classical Newton’s method. 相似文献
336.
New solid compounds of Al(III), Ga(III) and In(III) with chrysin were obtained. Their composition and some physicochemical properties were studied by thermogravimetric analysis, UV-vis, infrared and solid state 13C NMR spectroscopies. Upon heating the hydrated compounds M(C15H9O4)3·nH2O decomposed to the oxides. The structure of the compounds was elucidated on the basis of obtained results. 相似文献
337.
Antioxidants are gaining tremendous interest as chemopreventive as well as chemotherapeutic agents. Ellagic acid (EA) is a plant derived compound with very poor solubility in water and very low octanol/water partition coefficient and coenzyme Q10 (CoQ10) is a highly lipophilic compound, which is synthesized in the body and can be derived from food supplements as well. The new insights in the combination therapy are promising a better future in many challenging diseases. Synergism is among the key advantages of combination therapy apart from decreased intensity of unwanted effects of a compound, increased patient compliance and reduction in cost of therapy. EA and CoQ10 supplementation in combination will be beneficial in strengthening the weakened antioxidant defense system in many diseases related to oxidative stress. Here we report first derivative UV spectroscopic and HPLC methods for the simultaneous analysis of these two agents in pharmaceutical preparations. Results obtained indicate that the derivative spectroscopy is as efficient as HPLC method in quantitative analysis. Retention of ellagic acid can be increased using PEG bonded column which is poorly retained on C18 column. PEG column can be used for rapid simultaneous analysis of EA and CoQ10, which are having diverse physicochemical properties. 相似文献
338.
Yuzhao Wang 《偏微分方程通讯》2013,38(10):1694-1722
339.
运用荧光光谱法研究了共存物亚硝酸钠、葡萄糖或维生素C对白杨素(CHR)与牛血清白蛋白(BSA)相互作用的影响.结果表明:无共存物时,白杨素对BSA的荧光猝灭过程为静态猝灭,结合常数K值为10~3~10~4数量级,结合位点数n近似等于1,分子间相互作用力以疏水作用力为主;亚硝酸钠、葡萄糖、维生素C分别参与下,白杨素对BSA的荧光猝灭类型由静态猝灭转变为动态猝灭,葡萄糖的参与使白杨素与BSA之间作用力类型由疏水作用力转为氢键与范德华力,亚硝酸钠或维生素C的分别存在不影响白杨素与BSA的作用力类型;三种外加试剂的单独参与均使得白杨素与BSA的结合常数明显增大,结合位点数略有增加,但仍维持在1左右.初步探讨了共存物影响白杨素与BSA结合的可能方式. 相似文献
340.
Djurdje Cvijovi? 《Applied mathematics and computation》2009,215(8):3002-3006
In a recent paper, Adamchik [1] expressed in a closed-form symbolic derivatives of four functions belonging to the class of functions whose derivatives are polynomials in terms of the same functions. In this sequel, simple closed-form higher derivative formulae which involve the Carlitz-Scoville higher order tangent and secant numbers are derived for eight trigonometric and hyperbolic functions. 相似文献