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231.
Hook (Berberidaceae) has yielded the lactams (±)-nuevamine (7) and (±)-lennoxamine (8). Nuevamine is the first known isoindoloisoquinoline alkaloid, while lennoxamine is an isoindolobenzazepine structurally related to (±)-chilenine (3). 相似文献
232.
Marcel Azzaro Serge Geribaldi Bruno Videau Maurice Chastrette 《Magnetic resonance in chemistry : MRC》1984,22(1):11-15
The 13C NMR spectra of eleven 3-N,N-dialkylamino-5,5-dimethylcyclohex-2-en-1-ones have been determined. The chemical shifts of the three sp2 carbons and of the two methylene carbons on the cyclohexenone moiety have been subjected to factor analysis. Two factors are necessary and sufficient to account for more than 93% of the total variance. The more important axis (79%) corresponds to a factor closely related to the inductive and steric effects of the alkyl nitrogen substituents. The second parameter is more difficult to interpret and could correspond to the ‘ipso effects’ of amino groups. 相似文献
233.
George A. Olah Maurice Stephenson Joe G. Shih V. V. Krishnamurthy G. K. Surya Prakash 《Journal of fluorine chemistry》1988,40(2-3)
One bond 13C-19F coupling constant is used as a criterion to measure the extent of fluorine non-bonded electron pair back-donation to a carbenium center in a series of α-fluorodiarylcarbenium ions
. The electron demand at the cationic center was probed by systematically changing the nature of substituents on the phenyl rings, applying the tool of increasing electron demand to the study. 相似文献
234.
We consider how the Kelvin–Helmholtz instability is affected by an external hyperbolic strain flow. The basic flow being unsteady, the inviscid evolution of perturbations is studied within the framework of a non-normal analysis in which the maximum amplification is computed for any given time. A positive or negative stretching is shown to enhance or reduce, respectively, the instability even for weak stretching rates. To cite this article: T. Gomez, M. Rossi, C. R. Mecanique 331 (2003). 相似文献
235.
We express the condition for a phase space Gaussian to be the Wigner distribution of a mixed quantum state in terms of the
symplectic capacity of the associated Wigner ellipsoid. Our results are motivated by Hardy’s formulation of the uncertainty
principle for a function and its Fourier transform. As a consequence we are able to state a more general form of Hardy’s theorem.
The authors were supported under the EU-project MEXT-CT-2004-51715. 相似文献
236.
Jeroen Suijs Peter Borm Herbert Hamers Marieke Quant Maurice Koster 《Annals of Operations Research》2005,137(1):117-140
This paper focuses on sharing the costs and revenues of maintaining a public network communication structure. Revenues are
assumed to be bilateral and communication links are publicly available but costly. It is assumed that agents are located at
the vertices of an undirected graph in which the edges represent all possible communication links. We take the approach from
cooperative game theory and focus on the corresponding network game in coalitional form which relates any coalition of agents
to its highest possible net benefit, i.e., the net benefit corresponding to an optimal operative network. Although finding
an optimal network in general is a difficult problem, it is shown that corresponding network games are (totally) balanced.
In the proof of this result a specific relaxation, duality and techniques of linear production games with committee control
play a role. Sufficient conditions for convexity of network games are derived. Possible extensions of the model and its results
are discussed.
The research of Jeroen Suijs has been made possible by a fellowship of the Royal Netherlands Academy of Arts and Sciences. 相似文献
237.
C. Kippenberger F. Fischer C. Reinhardt J. Coquillion J. F. Willard G. Neumann H. Drehschmidt Klas Sondén Wilhelm Thörner W. Mac Farlone P. Caldwell R. Namias Binder W. E. Adeney W. Younger Vivian B. Lewes T. Lonatscheffsky-Petruniaka Maurice Meslans M. Arndt G. Pfeiffer Sigmund Neumann A. Lwoff F. Cowes S. B. Redwood S. Waters Murdy J. A. Wanklyn W. J. Cooper L. L. de Koninck und G. Linossier 《Fresenius' Journal of Analytical Chemistry》1896,35(1):184-200
Ohne Zusammenfassung 相似文献
238.
Ohne Zusammenfassung 相似文献
239.
240.
A simple means is described for the rapid equilibration of oxygen in fluorescence quenching reactions. This involves bubbling the gas through experimental solutions. With this procedure, data for Stern-Volmer plots can be obtained in 1–2 h, without bubbling it takes approximately ten times as long to collect such data. 相似文献