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1.
Milovan M. Stoiljković Igor A. Pašti Miloš D. Momčilović Jelena J. Savović Mirjana S. Pavlović 《Spectrochimica Acta Part B: Atomic Spectroscopy》2010
Enhancement of emission line intensities by induced oscillations of direct current (DC) arc plasma with continuous aerosol sample supply was investigated using multivariate statistics. Principal component analysis (PCA) was employed to evaluate enhancements of 34 atomic spectral lines belonging to 33 elements and 35 ionic spectral lines belonging to 23 elements. Correlation and classification of the elements were done not only by a single property such as the first ionization energy, but also by considering other relevant parameters. Special attention was paid to the influence of the oxide bond strength in an attempt to clarify/predict the enhancement effect. Energies of vaporization, atomization, and excitation were also considered in the analysis. In the case of atomic lines, the best correlation between the enhancements and first ionization energies was obtained as a negative correlation, with weak consistency in grouping of elements in score plots. Conversely, in the case of ionic lines, the best correlation of the enhancements with the sum of the first ionization energies and oxide bond energies was obtained as a positive correlation, with four distinctive groups of elements. The role of the gas-phase atom-oxide bond energy in the entire enhancement effect is underlined. 相似文献
2.
The construction of the sum of a direct (semilattice ordered) system of algebras introduced by J. Plonka – later known as the Plonka sum – is one of the most important methods of composition in universal algebra, having a number of applications in different algebraic theories, such as semigroup theory, semiring theory, etc. In this paper we present a more general way for constructing algebras with involution, that is, algebraic systems equipped with a unary involutorial operation which is at the same time an antiautomorphism of the underlying algebra. It is the sum – involutorial Plonka sum, as we call it – of an involution semilattice ordered system of algebras. We investigate its basic properties, as well as the problem of its subdirect decomposition. 相似文献
3.
Dragan Dimitrovski Dragana Radosavljevi? Miloje Rajovi? Rade Stoiljkovi? 《Acta Mathematica Hungarica》2011,132(1-2):15-26
It is shown that Sturm theorems, formulated in the 1830??s ([1], [2], [3] and [4]) and valid for second order linear homogeneous differential equation L(y)??y??+a(x)y??+b(x)y=0, could as well be formulated for the class of nonhomogeneous linear differential equations L(y)=f(x). Criteria for the existence of oscillatory solutions of nonhomogeneous equations, as well as more exact locations of the zeros are given. 相似文献
4.
Dragan Vujovic Jelena Popovic Djordjevic Milovan Velickovic Vele Tesevic 《Natural product research》2016,30(8):987-990
This work aimed to evaluate the total contents of polyphenolics (the Ribereau-Gayon–Maurié procedure), anthocyanins (using pH differential method) and tannins (the Nègre procedure) as well as the content of phenolic acids (using UPLC/MS chromatography), respectively of the wines obtained from three new Merlot clone candidates in the perennial clonal selection. The aforementioned chemical parameters were determined in the samples covering the period 2009–2012. In comparison both with the standard Merlot wine (mother vine) and the wines obtained from other two clone candidates, the Merlot wine of the clone candidate No. 022 was found to have the highest total content of all three examined components 1.89 ± 0.05 g/L (polyphenolics), 185.59 ± 5.00 mg/L (anthocyanins) and 1.11 ± 0.03 g/L (tannins), as well as six phenolic acids including gallic acid (25.49 ± 0.27 mg/L). These findings are in good agreement with the observed trend for the viticultural parameters indicating the clone candidate No. 022 as more promising than mother. 相似文献
5.
V.?Dmitra?inovi? Toru?Sato Milovan??uvakov 《The European Physical Journal C - Particles and Fields》2009,62(2):383-397
We calculate the energies of three-quark states with definite permutation symmetry (i.e. of SU(6) multiplets) in the N=0, 1, 2 shells, confined by the Y-string three-quark potential. The exact Y-string potential consists of one term, the so-called
three-string term, and three angle-dependent two-string terms. Due to this technical complication we treat the problem at
three increasingly accurate levels of approximation: (1) the (approximate) three-string potential expanded to first order
in trigonometric functions of hyper-spherical angles; (2) the (approximate) three-string potential to all orders in the power
expansion in hyper-spherical harmonics, but without taking into account the transition(s) to two-string potentials; (3) the
exact minimal-length string potential to all orders in a power expansion in the hyper-spherical harmonics, and taking into
account the transition(s) to two-string potentials. We show the general trend of improvement of these approximations: the
exact non-perturbative corrections to the total energy are of the order of one per cent, as compared with approximation (2),
yet the exact energy differences between the [20,1+],[70,2+],[56,2+],[70,0+]-plets are shifted to 2:2:0.9, from the Bowler and Tynemouth separation rule 2:2:1, which is obeyed by approximation (2)
at the one per cent level. The precise value of the energy separation of the first radial excitation (“Roper”) [56′,0+]-plet from the [70,1−]-plet depends on the approximation, but does not become negative, i.e. the “Roper” remains heavier than the odd-parity [70,1−]-plet in all of our approximations. 相似文献
6.
7.
Silica Gel as a Promoter of Sequential Aza‐Michael/Michael Reactions of Amines and Propiolic Esters: Solvent‐ and Metal‐Free Synthesis of Polyfunctionalized Conjugated Dienes
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Dr. Jovana Aleksić Dr. Milovan Stojanović Prof. Dr. Marija Baranac‐Stojanović 《化学:亚洲杂志》2018,13(14):1811-1835
We present an efficient, simple, metal‐ and solvent‐free silica‐gel‐promoted synthesis of functionalized conjugated dienes by sequential aza‐Michael/Michael reactions by starting from commercially available primary amines and propiolic esters. The scope and usefulness of the method is demonstrated for 31 examples, including a range of propiolic esters, aliphatic amines, and differently substituted aromatic amines. For aliphatic amines, the products were obtained within 0.5 to 4 h in 52 to 85 % yield, compared with 3.5 to 22 h under classical solution‐phase synthesis, which proceeds with similar or lower yields. The method was found to be particularly useful for weakly nucleophilic aromatic amines, which provided products in 21 to 73 % yield over 2.5 to 9.5 h compared with yields of 0 to 49 % over 1 to 6 d under standard solution‐phase conditions, and for more hydrophobic esters that gave products in yields of 47 to 79 % over 1 to 3 h compared with 0 to 45 % over 4 to 114 h in solvent. 相似文献
8.
Karanikić Petra Milovančević Miloš 《Journal of Radioanalytical and Nuclear Chemistry》2021,330(3):1037-1043
Journal of Radioanalytical and Nuclear Chemistry - The study's major goal was to identify the most significant coccoliths based on foraminiferal species and fragment abundances, oxygen isotope... 相似文献
9.
S. Rai Marija Todorovi Ivanka Holclajtner-Antunovi Milovan Stoiljkovi 《Fresenius' Journal of Analytical Chemistry》1999,365(4):367-370
A spetroscopic method for the determination of metal traces (Mn, Cu, Fe) in wine has been developed based on argon stabilized
d.c. arc plasma at atmospheric pressure. The experimental conditions were optimized using lateral distributions of spectral
line intensities of the trace elements in aqueous and ethanol-aqueous solutions. The method was applied to the analysis of
6 wines from 3 Serbian wine-growing regions. Direct and standard addition methods were tested. The precision of the method
is characterized by a relative standard deviation of 0.50– 3.00%. The accuracy of the method was assessed by flame AAS.
Received: 8 October 1998 / Revised: 17 March 1999 / Accepted: 20 March 1999 相似文献
10.
Milovan D. Živanović Miomir K. Vukobratović 《Archive of Applied Mechanics (Ingenieur Archiv)》2006,75(2-3):125-137
Tracking inputs and trajectories of mechanical systems as control objects is analyzed with an emphasis on the objects having
the number of external inputs different from the number of their degrees of freedom (DOFs). The problems of the synthesis
of the realizable nominals and control laws were considered especially for the case where the number of DOFs of the control
object is larger than the number of its external inputs. The difference between control laws for nominals tracking and regulation
laws is demonstrated. 相似文献