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排序方式: 共有79条查询结果,搜索用时 15 毫秒
1.
R. S. Saxena Reshma D. Parikh K. C. Gupta 《Monatshefte für Chemie / Chemical Monthly》1984,115(2):141-146
Potentiometric and conductometric studies on the zinc, cadmium, lead—methylene bis thio acetic acid system in aqueous media reveal the formation of 1:1 and 1:2 (M:L) complexes in thepH range 3.4–5.1. Their stability constants have been determined at 20°, 30° and 40 °C by applyingCalvin andMelchior's extension ofBjerrum's method. The overall changes in thermodynamic function H, G and S accompanying complexation have been evaluated at 30 °C.
Elektrochemische Untersuchungen über Zusammensetzung, Stabilität und Thermodynamik von Zn(II)-, Cd(II)- und Pb(II)-Komplexen mit Methylen-bisthioessigsäure
Zusammenfassung Potentiometrische und konduktometrische Untersuchungen an Zink-, Cadmium- und Blei-Methylen-bis-thioessigsäure-Systemen in wäßrigem Medium zeigten die Bildung von 1:1 und 1:2 (M:L)-Komplexen impH-Bereich 3,4–5,1. Die Stabilitätskonstanten wurden bei 20°, 30° und 40 °C mittels derCalvin-Melchior-Methode (erweiterteBjerrum-Methode) bestimmt. Die thermodynamischen Parameter H, G und S der Komplexierung wurden für 30 °C ermittelt.相似文献
2.
A simple and inexpensive method for immobilizing alpha-amylase from Bacillus circulans GRS 313 on coconut fiber was developed. The immobilization conditions for highest efficiency were optimized with respect to immobilization pH of 5.5, 30 degrees C, contact time of 4 h, and enzyme to support a ratio of 1:1 containing 0.12 mg/mL of protein. The catalytic properties of the immobilized enzyme were compared with that of the free enzyme. The activity of amylase adsorbed on coconut fiber was 38.7 U/g of fiber at its optimum pH of 5.7 and 48 degrees C, compared with the maximum activity of 40.2 U/mL of free enzyme at the optimum pH of 4.9 and 48 degrees C. The reutilization capacity of the immobilized enzyme was up to three cycles. 相似文献
3.
The resolutions of determinantal ideals exhibit a remarkable stability property: for fixed rank but growing dimension, the terms of the resolution stabilize (in an appropriate sense). One may wonder if other sequences of ideals or modules over coordinate rings of matrices exhibit similar behavior. We show that this is indeed the case. In fact, our main theorem is more fundamental in nature: It states that certain large algebraic structures (which are examples of twisted commutative algebras) are noetherian. These are important new examples of large noetherian algebraic structures, and ones that are in some ways quite different from previous examples. 相似文献
4.
5.
A.K. Nagpal 《Nuclear Physics B》1974,72(2):359-364
The casual propagation of Hurley wave equations for a massive particle with an arbitrary spin s, interacting minimally with an external electromagnetic field, is found to be due to the nature of the β-matrices satisfying Harish Chandra's condition analogous to the spin-one case. 相似文献
6.
Alonso AM Horcajada R Groombridge HJ Mandalia R Motevalli M Utley JH Wyatt PB 《Chemical communications (Cambridge, England)》2004,(4):412-413
Electrochemical reduction of enantiomerically pure amino- and alkoxy-phenazine derivatives forms strongly basic radical anions which give asymmetric induction in the conversion of 3,4-epoxytetrahydrothiophene-1,1-dioxide into the allylic ester with facile regeneration of the phenazine. 相似文献
7.
Abhishek Verma Swati Nagpal Praveen K. Pandey P. K. Bhatnagar P. C. Mathur 《Journal of nanoparticle research》2007,9(6):1125-1131
Quantum Dots of CdS
x
Se1−x
embedded in borosilicate glass matrix have been grown using Double-Step annealing method. Optical characterization of the
quantum dots has been done through the combinative analysis of optical absorption and photoluminescence spectroscopy at room
temperature. Decreasing trend of photoluminescence intensity with aging has been observed and is attributed to trap elimination.
The changes in particle size, size distribution, number of quantum dots, volume fraction, trap related phenomenon and Gibbs
free energy of quantum dots, has been explained on the basis of the diffusion-controlled growth process, which continues with
passage of time. For a typical case, it was found that after 24 months of aging, the average radii increased from 3.05 to
3.12 nm with the increase in number of quantum dots by 190% and the size-dispersion decreased from 10.8% to 9.9%. For this
sample, the initial size range of the quantum dots was 2.85 to 3.18 nm. After that no significant change was found in these
parameters for the next 12 months. This shows that the system attains almost a stable nature after 24 months of aging. It
was also observed that the size-dispersion in quantum dots reduces with the increase in annealing duration, but at the cost
of quantum confinement effect. Therefore, a trade off optimization has to be done between the size-dispersion and the quantum
confinement. 相似文献
8.
The physical state of benzoic acid (BA) and its interaction with ethyl cellulose (EC) were examined in ethyl cellulose—benzoic acid matrices by Differential Scanning Calorimetry (DSC). The glass transition temperature (Tg) of EC of various matrices having BA in solid solution form (upto 27.7%) was reduced. The BA in matrices containing more than 38.9% drug exhibited distinct melting endotherms due to crystalline form. The peak temperatures of these endotherms were lowered and they broadened as the concentration was lowered. The solubility of BA increased at its melting point as compared to ambient temperature. The melting enthalpy of BA, when plotted as a function of its concentration yielded a straight line with intercept of 330 mg g–1 of matrix. This is the solubility of BA in EC at its melting temperature. Fourier Transform Infra Red Spectroscopy (FTIR) investigations confirmed that hydrogen bonding occurred between EC and BA through hydroxyl groups.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
9.
Reshma Khemchandani Nishil Gupta Arpit Chaudhary Suresh Chandra 《Optimization Letters》2013,7(3):575-592
In this paper, we develop optimal trading strategies for a risk averse investor by minimizing the expected cost and the risk of execution. Here we consider a law of motion for price which uses a convex combination of temporary and permanent market impact. In the special case of unconstrained problem for a risk neutral investor, we obtain a closed form solution for optimal trading strategies by using dynamic programming. For a general problem, we use a quadratic programming approach to get approximate dynamic optimal trading strategies. Further, numerical examples of optimal execution strategies are provided for illustration purposes. 相似文献
10.
Facile and efficient synthesis of sulfoxide esters using menthols as chiral auxiliary is described. Phenylthio/benzylthio/naphthylthioacetic esters act as an efficient substrate for chiral sulfoxides via oxidation in one step. The structural and stereochemical aspects of target product were established on the basis of various spectroscopic studies, namely FT-IR, NMR (1H NMR and 13C NMR) and elemental analysis. This method is simple, fast, convenient and very efficient. 相似文献