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91.
Harald Greger Ernst Haslinger Otmar Hofer 《Monatshefte für Chemie / Chemical Monthly》1982,113(3):375-379
A new sesquiterpene isofraxidin ether (isofraxidin=7-hydroxy-6,8-dimethoxy-coumarin) was isolated from the roots ofArtemisia alba and characterized by means of1H-nmr,13C-nmr, ms, uv, and ir. Albartin is an exomethylene isomer of 3-acetyloxy-drimartol isofraxidin ether with -OAc axial and -CH2OAr equatorial. The chemosystematic significance of this class of compounds within the genusArtemisia is briefly discussed.
Albartin — ein neuer Sesquiterpen-Cumarin-Ether ausArtemisia alba (Kurze Mitteilung)
Zusammenfassung Aus den Wurzeln vonArtemisia alba wurde ein neuer Sesquiterpen-Isofraxidin Ether (Isofraxidin = 7-Hydroxy-6,8-dimethoxy-cumarin) isoliert und mittels1H-NMR,13C-NMR, MS, UV und IR charakterisiert. Albartin ist ein exo-Methylen-Isomer von 3-Acetyloxy-drimartol-isofraxidin-ether mit-OAc axial und -CH2OAr equatorial. Die chemosystematische Bedeutung dieser Verbindungsklasse innerhalb der GattungArtemisia wird kurz diskutiert.相似文献
92.
Assuming that an inaccessible cardinal exists, we construct a ZFC-model where every
1
4
-set is measurable but there exists a
1
4
-set without the property of Baire. By a result of Shelah, an inaccessible cardinal is necessary for this result.The author is partially supported by the Basic Research Foundation of the Israel Academy of Sciences and by the Swiss National Funds. 相似文献
93.
The size dependence of micro-toughness in ductile fracture 总被引:1,自引:0,他引:1
Kartik Srinivasan Yonggang Huang Otmar Kolednik Thomas Siegmund 《Journal of the mechanics and physics of solids》2008,56(8):2707-2726
Micro-toughness in ductile fracture is defined as the plastic work dissipated per unit fracture surface area in the material separation processes of void growth and coalescence. A micromechanics model for the estimation of the size dependence of micro-toughness in ductile fracture is presented. Size effects are incorporated in the model using the conventional mechanism-based strain gradient plasticity (CMSG) theory. A finite element model of an axisymmetric representative unit cell with an initial spherical void is used to validate model predictions. Two characteristic length scales emerge from the model. The initial void radius sets the scale for the initial spherical void growth. For the subsequent void coalescence, the scale is set by the width of the intervoid ligament. Energy dissipation in ductile fracture is found to be dominated by the mechanisms of coalescence, and the micro-toughness in ductile fracture is found to be size dependent for dimple sizes approximately one order of magnitude larger than the material length scale. 相似文献
94.
Otmar Spinas 《Israel Journal of Mathematics》2007,162(1):57-73
We show that for every Borel function f:[2ω]
n
→ 2ω there exists a closed countably splitting family A such that f ↾ [A]
n
omits a perfect set of values in 2
ω
.
Work partially supported by DFG grant SP 683. 相似文献
95.
Roman Popielarz Otmar Vogt 《Journal of polymer science. Part A, Polymer chemistry》2008,46(11):3519-3532
Effect of coinitiator structure on relative initiation efficiency of two‐component Eosin/coinitiator systems has been evaluated quantitatively in polymerization of poly(ethylene glycol) diacrylate as an example monomer. The initiation efficiency has been measured by the Fluorescence Probe Technique (FPT), using Eosin both as a photoinitiator component and as a fluorescent probe. A LED/fiber optic‐based measurement system has been developed and applied in this study. It has been found that from among 17 compounds tested, the following coinitiators form most efficient photoinitiating systems in combination with Eosin, when exposed to visible light: coinitiator, relative efficiency = triethanolamine, 1.0; 2,6‐diisopropyl‐N,N‐dimethylaniline, 0.70; 2‐benzyl‐2‐(dimethylamino)‐4′‐morpholinobutyrophenone (Irgacure 369), 0.91; carbon tetrabromide, 2.1; [4‐[(2‐hydroxytetradecyl)oxy]phenyl]phenyliodonium hexafluoroantimonate (SarCat 1012), 28. These relative efficiencies refer to the following component concentrations: [Eosin] = 8.6 × 10?4 M, (0.05% by weight); [coinitiator] = 4.3 × 10?2 M. The factors affecting the initiation efficiency of the systems studied are discussed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3519–3532, 2008 相似文献
96.
Christoph Seger Thomas Pacher Harald Greger Ekarin Saifah Otmar Hofer 《Monatshefte für Chemie / Chemical Monthly》2002,133(1):97-100
Summary. The bisamide aglairubine was isolated from different Aglaia species. The original structure was revised on the basis of FDMS and 2D-NMR data. Since all isolates were obtained from species
belonging to the section Amoora of the genus Aglaia, aglairubine might serve as a taxonomic marker.
Received July 3, 2001. Accepted July 12, 2001 相似文献
97.
98.
Summary.
In this paper we prove that the Landweber iteration is a stable
method for solving nonlinear ill-posed problems. For perturbed data with
noise level we propose a stopping rule that yields the
convergence rate
)
under appropriate conditions. We
illustrate these conditions for a few examples.
Received
February 15, 1993 / Revised version received August 2, 1994 相似文献
99.
100.
Konstantinos Kalimeris Otmar Scherzer 《Mathematical Methods in the Applied Sciences》2013,36(16):2254-2264
In this paper, we derive time reversal imaging functionals for two strongly causal acoustic attenuation models, which have been proposed recently. The time reversal techniques are based on recently proposed ideas of Ammari et al. for the thermo‐viscous wave equation. Here and there, an asymptotic analysis provides reconstruction functionals from first order corrections for the attenuating effect. In addition, we present a novel approach for higher order corrections. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献