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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Phytochemistry 21 (1982), S. 1385-1387 
    ISSN: 0031-9422
    Keywords: 3α-hydroxy-lup-20(29)-ene-23,28-dioic acid. ; Araliaceae ; Schefflera octophylla ; triterpenes
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Phytochemistry 23 (1984), S. 2889-2891 
    ISSN: 0031-9422
    Keywords: 3α, 11α-dihydroxylup-20(29)-en-28-oic acid and 3α, ; Acanthopanax trifoliatus ; Araliaceae ; lupenes ; triterpenes
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Phytochemistry 23 (1984), S. 1695-1697 
    ISSN: 0031-9422
    Keywords: 3α,11α-dihydroxylup-20(29)-ene-23,28-dioic acid. ; Araliaceae ; Schefflera octophylla ; triterpenes
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0031-9422
    Keywords: 3α-hydroxy-lup-20(29)-ene-23,28-dioic acid. ; Araliaceae ; Schefflera octophylla ; oleanolic acid ; triterpene fatty acid esters
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Numerische Mathematik 53 (1988), S. 653-661 
    ISSN: 0945-3245
    Keywords: AMS(MOS): 65H10 ; 15A48 ; CR: G1.5
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary As shown in preceding papers of the authors, the verification of anR-convergence order τ for sequences coupled by a system (1.1) of basic inequalities can be reduced to the positive solvability of system (3.3) of linear inequalities. Further, the bestR-order $$\bar \tau$$ implied by (1.1) is equal to the minimal spectral radius of certain matrices composed from the exponents occuring in (1.1). Now, these results are proven in a unified and essentially simpler way. Moreover, they are somewhat extended in order to facilitate applications to concrete methods.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Computing 53 (1994), S. 137-154 
    ISSN: 1436-5057
    Keywords: 65D05 ; 65D07 ; 41A15 ; Shape preserving interpolation of scattered data ; range restrictions ; Powell-Sabin splines ; minimum norm modification ; thin plate functional
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Behandelt wird die Interpolation unregelmäßig verteilter Daten durch quadratische Powell-Sabin-Splines, wobei stückweise konstante obere und untere Schranken für die Funktionswerte der Interpolierenden vorgegeben sind. Die hergeleiteten hinreichenden Bedingungen für die Einhaltung der zweiseitigen Schranken ergeben ein lösbares lineares Ungleichungssytem für die Gradienten als Parameter, welches bezüglich der Datenpunkte separiert ist. Die Auswahl von visuell gefälligen Interpolierenden erfolgt durch die Minimierung geeigneter Funktionale.
    Notes: Abstract The construction of range restricted bivariateC 1 interpolants to scattered data is considered. In particular, we deal with quadratic spline interpolation on a Powell-Sabin refinement of a triangulation of the data sites subject to piecewise constant lower and upper bounds on the values of the interpolant. The derived sufficient conditions for the fulfillment of the range restrictions result in a solvable system of linear inequalities for the gradients as parameters, which is separated with respect to the data sites. Since there exists an infinite number of spline interpolants meeting the constraints, the selection of a visually pleasant solution is based on the minimum norm modification of a suitable initial interpolant or on the minimization of the thin plate functional. While the first proposal reduces to the solution of independent local quadratic programs, the second proposal results in a global quadratic optimization problem.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Computing 44 (1990), S. 365-368 
    ISSN: 1436-5057
    Keywords: 65D07 ; 41A15 ; Positive spline interpolation ; sufficient and necessary existence condition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Es wird eine hinreichend und notwendige Bedingung für die Positivität von rational-kubischen Splines angegeben, welche sich leicht überprüfen läßt. Sie ist bei Interpolationsdaten mit positiven Ordinaten durch hinreichend große Rationalitätsparameter stets erfüllbar.
    Notes: Abstract By means of a finite set of inequalities a sufficient and necessary condition for the positivity of rational cubic splines is given which holds true whenever the rationality parameters are sufficiently large.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Computing 36 (1986), S. 335-342 
    ISSN: 1436-5057
    Keywords: 65D07 ; 41A15 ; 90C20 ; Convexity conditions ; weakly coupled system of inequalities ; numerical algorithms ; quadratic programming ; unconstrained dual program with tridiagonal Hessian
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Während die Aufgabe der konvexen Interpolation im Falle kubischer Splines im allgemeineen nicht lösbar ist, kann jetzt gezeigt werden, daß sie bei Verwendung von Exponentialsplines Lösungen besitzt sofern die vorkommenden Parameter hinreichend roß sind, und es werden konkrete hinreichende und notwendige Lösbarkeitsbedingungen hergeleitet. Da eindeutige Lösbarkeit in der Regel nicht vorliegt, wird eine Auswahlfunktion eingeführt und das entstehende quadratische Optimierungsproblem nach Dualisierung numerisch behandelt.
    Notes: Abstract Sufficient and necessary conditions are derived under which interpolating splines are convex if the data set is in convex position. In order to select one of the interpolants, by means of a well-known objective function a quadratic optimization problem is stated which can be solved effectively by passing to a dual program.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Computing 47 (1991), S. 87-96 
    ISSN: 1436-5057
    Keywords: 65D07 ; 41A15 ; 41A63 ; S-convex spline interpolation ; existence conditions ; search procedure for constructingS-convex splines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung In dieser Arbiet wird eine notwendige und hinreichende Bedingung für dieS-Konvexität von rational-biquadratischen Spline interpolierenden auf Rechteckgittern hergeleitet. Da Kriterium kann in Form von linearen Gleichungen und konvexen Ungleichungen formuliert werden, und es wird gezeigt, daß diese im Fall von hinreichend großen Rationalitätsparametern erfüllbar sind, sofer sind die zu interpolierende Datenmenge inS-konvexer Lage befindet.
    Notes: Abstract The purpose of this paper is to give a necessary and sufficient condition for theS-convexity of rational biquadraticC 1-spline interpolants on rectangular grids. The criterion is described in form of linear equalities and convex inequalities, and forS-convex data sets the criterion can be satisfied whenever the rationality parameters are sufficiently large.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Computing 38 (1987), S. 261-267 
    ISSN: 1436-5057
    Keywords: 65D07 ; 41A15 ; Existence conditions ; construction os positive splines ; minimization of the curvature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Unter positiver Interpolation wird die Aufgabenstellung verstanden, zur einer nichtnegativen Datenmenge nichtnegative Interpolierende zu konstruieren. Im Fallen rational-quadratischer Splines wird eine notwendige und hinreichende Bedingung für die Durchführbarkeit positiver Interpolation hergeleitet, und es wird gezeigt, daß diese sich bei passender Wahl der vorkommenden Parameter stets erfüllen läßt.
    Notes: Abstract A necessary and sufficient criterion is presented under which the property of positivity carry over from the data set to rational quadratic spline interpolants. The criterion can always be satisfied if the occuring parameters are properly chosen.
    Type of Medium: Electronic Resource
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