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排序方式: 共有193条查询结果,搜索用时 0 毫秒
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Highly regioselective annulation reactions of unsymmetrically substituted alkynes by primary 2-bromo or 2-chloroanilines are achieved with an efficient one-pot protocol, which relies on a regioselective TiCl4-catalyzed intermolecular hydroamination and a subsequent palladium-catalyzed intramolecular aza-Heck reaction. The use of unsymmetrically substituted alkynes in this strategy enables the synthesis of diversely functionalized indoles, with a regioselectivity that is complementary to the one obtained when employing Larock's annulation reaction. 相似文献
23.
We prove that the Chern character of quantum algebras is invariant under a class of deformations of the Dirac operator. We also extend the definition of the Chern character to include certain unbounded operators. 相似文献
24.
Stephanie Kaspar Diana Weier Winfriede Weschke Hans-Peter Mock Andrea Matros 《Analytical and bioanalytical chemistry》2010,398(7-8):2883-2893
Both the nucellar projection (NP) and endosperm transfer cells (ETC) of the developing barley grain (harvested 8 days after flowering) were isolated by laser capture micro-dissection combined with pressure catapulting. Protein extracts were analyzed by nanoUPLC separation combined with ESI-Q-TOF mass spectrometry. The majority of the ~160 proteins identified were involved in translation, protein synthesis, or protein destination. The NP proteome was enriched for stress defense molecules, while proteins involved in assimilate transport and the mobilization of nutrients were common to both the NP and the ETC. The combined qualitative and quantitative protein profiling allowed for the identification of several proteins showing tissue specificity in their expression, which underlines the distinct biological functions of these two tissues within the developing barley grain. 相似文献
25.
Kaspar Nipp 《BIT Numerical Mathematics》2002,42(2):408-439
The dynamics of a differential algebraic equation takes place on a lower dimensional manifold in phase space. Applying a numerical integration scheme, it is natural to ask if and how this geometric property is preserved by the discrete dynamical system. In the index-1 case answers to this question are obtained from the singularly perturbed case treated by Nipp and Stoffer, Numer. Math. 70 (1995), 245–257, for Runge-Kutta methods and in K. Nipp and D. Stoffer, Numer. Math. 74 (1996), 305–323, for linear multistep methods. As main result of this paper it is shown that also for Runge-Kutta methods and linear multistep methods applied to a index-2 problem of Hessenberg form there is a (attractive) invariant manifold for the discrete dynamical system and this manifold is close to the manifold of the differential algebraic equation. 相似文献
26.
O. Kaspar Personne Schneider W. Lenz und E. Kock 《Fresenius' Journal of Analytical Chemistry》1882,21(1):294-295
Ohne Zusammenfassung 相似文献
27.
J. Gwinner H. Läpple Ch. Schneeweiß H. G. Bartels E. Kaspar K. -H. Waldmann R. Horst R. Hebel H. Späth 《Mathematical Methods of Operations Research》1977,21(4):B159-B164
Ohne Zusammenfassung 相似文献
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