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In this paper we consider certain matrix equations in the field of Mikusiński operators, and construct a method for obtaining an approximate solution which allows working with numerical constants instead of operators. The theory of diagonally dominant matrices is applied for the analysis, existence and character of the obtained solutions. We introduce a method for determining approximate solutions of a discrete analogue for operational differential equations and give conditions for their existence. The error of the approximation is estimated.  相似文献   
2.
The synthesis of 7,8-dihydroxy-2-(2-methoxycarbonylethyl)-4,9-dioxa-2-azabicyclo[4.2.1]nonane- 3-thione ( 16 ) and of its parents 9-oxa-4-thia-3-thione 17 , and 9-oxa-4-thia-3-one 18 is described. The conversion of 5′-deoxy-5′-iodo-2′,3′-O, O-isopropylidene-5,6-dihydrouridin ( 1 ) into the 2-O-methyl-5,6-dihydrouridine 5 , the 5′-O-acetyl-5,6-dihydrouridine 4 , and into the N-(5-O-acetyl-2,3-O, O-isopropylidene-β-D -ribofuranosyl)-N-(2-methoxycarbonyl thyl)-urea ( 6 ) invoked 2′,3′-O, O-isopropylidene-2,5′-anhydro-5,6-dihydrouridine ( 2 ) as the common intermediate.  相似文献   
3.
The nonhomogeneous time-fractional diffusion equation is analyzed in the frames of the Mikusiński calculus. The exact and the approximate solution of the considered problem are constructed and their character is analyzed.  相似文献   
4.
Djurdjica Taka i 《PAMM》2004,4(1):720-721
The approximate solution of a class of differential equations, in the field of Mikusiński operators is constructed by using the Taylor method. The obtained results are applied to a class of partial integro–differential equations. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
5.
In this paper, research on some problematic aspects high school students have in learning trigonometry is presented. It is based on making sense of mathematics through perception, operation and reason in the case of trigonometry. We analyzed students' understanding of trigonometric concepts in the frame of triangle and circle trigonometry contexts, as well as the transition between these two contexts. In the conclusion, we present some new problematic aspects we noticed.

The research was carried out with two groups of high school students, one of them at the beginning of their trigonometry learning (17 years old) and the other at the end of their high school education (19 years old). The students were given a questionnaire similar to that of Chin and Tall, and we analyzed the students' response. In our research, we noticed that students have difficulties with properties of periodicity and the fact that trigonometric functions are not one-to-one. In addition, there is poor understanding of radian measure and a lack of its connection to the unit circle.  相似文献   

6.
Polymerization of tetrafluoroethylene in monochlorodifluoromethane was carried out at low temperatures with -prays from a 60Co source. An activation energy of 4.3 kcal/mole was obtained for the in-source polymerization, and this is higher than that of bulk polymerization, 2.7 kcal/mole. It was found that a remarkable postpolymerization takes place even if the reaction system is in liquid state. A kinetic treatment for the postpolymerization is described.  相似文献   
7.
Djurdjica Takaci 《PAMM》2003,3(1):581-582
We consider a class of partial integro‐differential equations with appropriate conditions and its corresponding equation in the field of Mikusiński operators. As is usual in numerical analysis, we construct the corresponding difference equation, determine its solution, analyze its character and treat it as the approximate solution of the considered problem. We also estimate the error of approximation.  相似文献   
8.
The approximate solution of a class of nonlinear differential equations, in the field of Mikusiński operators is constructed by using the Euler method. The obtained results are applied to a class of partial integro–differential equations. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
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