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排序方式: 共有1205条查询结果,搜索用时 15 毫秒
121.
122.
Mihály Viktor Pilipecz Tamás Róbert Varga Pál Scheiber Zoltán Mucsi Amélie Fàvre-Mourgues Sándor Boros László Balázs Gábor Tóth Péter Nemes 《Tetrahedron》2012,68(27-28):5547-5553
Using different reducing methods unsaturated indolizidine and quinolizidine lactams substituted with a nitro group were transformed into various alkaloid-like derivatives. Hydrogen transfer and palladium catalyzed hydrogenation gave compounds of ketolactam or lactam type meanwhile the nitro group was eliminated. On the other hand, in presence of Raney-nickel catalyst the nitro compounds were reduced to diastereomeric amino derivatives whose stereochemistry was elucidated by NMR spectroscopy. Using sodium bis-dimethoxy-ethoxy-aluminum-hydride (Red-Al) as reducing agent an unexpected tricyclic azetidine was isolated and characterized. 相似文献
123.
A new numerical algorithm for computation of phase response curves of stable limit cycle oscillators is proposed. The idea
of the algorithm originates from a direct method that is based on computation of the oscillator response to short finite pulses
delivered at different phases of oscillations. Here we adapt the direct method to the case of infinitesimal perturbations
and compare our algorithm with the standard algorithm based on the backward integration of the adjoint equations. In contrast
to the standard algorithm, our algorithm does not require any backward integration and it is easier to program since a necessity
of numerical interpolation for the Jacobian matrix is avoided. In addition, we demonstrate by examples that our algorithm
is faster than the standard algorithm and this advantage is especially notable for weakly stable limit cycle oscillators. 相似文献
124.
125.
126.
Several transition metal-mediated oxidations using hypervalent iodine species are reported. A convenient procedure for preparation of iodylarenes via RuCl3-catalyzed oxidation of iodoarenes has been developed. This procedure allows the generation of highly reactive monomeric iodine(V) species, which are excellent oxidants toward alcohols and hydrocarbons in situ. A broad range of substrates can be oxidized to carbonyl compounds by a tandem catalytic system based on the Ru(III)-catalyzed reoxidation of ArIO to ArIO2 using Oxone® as oxidant. It was shown that electrophilic iodine(III) species, originating from oligomeric iodosylbenzene sulfate (PhIO)3SO3, are efficient oxygenating agents in catalytic oxidation of aromatic hydrocarbons in the presence of metalloporphyrin complexes. 相似文献
127.
128.
Sabir Jacquir Stéphane Binczak Jean-Marie Bilbault Viktor Kazantsev Vladimir Nekorkin 《Nonlinear dynamics》2006,44(1-4):29-36
An electrical circuit is proposed to realize an unidirectional coupling between two cells, mimicking chemical synaptic coupling.
Each cell represents the FitzHugh–Nagumo (FHN) model of neuron with a modified exitability (MFHN). We present experimental
results on frequency doublings and on the chaotic dynamics depending on the coupling strength in a master–slave configuration.
In all experiments, we stress the influence of the coupling strength on the control of the slave neuron. 相似文献
129.
We describe affine functions on spaces with an upper curvature bound. 相似文献
130.
Viktor L. Ginzburg 《Mathematische Zeitschrift》1992,210(1):625-640
The Research was partially supported by NSF Grant DMS 8505550 相似文献