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41.
[Structure: see text] Dicobalt hexacarbonyl propargyl complexes, prepared from alkynyl ketoses, display an unexpected reactivity when treated with Lewis acids in the presence of nucleophiles and furnish C-ketosides, branched-chain C-ketosides, or branched-chain C-glycals depending on the nucleophile and the carbohydrate starting material. 相似文献
42.
We study the effect of a magnetic field on the behaviour of a slender conducting elastic structure, motivated by stability
problems of electrodynamic space tethers. Both static (buckling) and dynamic (whirling) instability are considered and we
also compute post-buckling configurations. The equations used are the geometrically exact Kirchhoff equations. Magnetic buckling
of a welded rod is found to be described by a surprisingly degenerate bifurcation, which is unfolded when both transverse
anisotropy of the rod and angular velocity are considered. By solving the linearised equations about the (quasi-) stationary
solutions, we find various secondary instabilities. Our results are relevant for current designs of electrodynamic space tethers
and potentially for future applications in nano- and molecular wires. 相似文献
43.
Cecilio Marquez Rosa M. Rabanal Serafiin Valverde Liliana Eguren Aurea Perales Jos Fayos 《Tetrahedron letters》1980,21(52):5039-5042
Two diterpenes, capitatin 4 and teucapitatin 5 have been isolated from Teucrium capitatum. The X-ray structure of 4, including absolute stereochemistry, is given. Diterpene 4 has been chemically related to picropolin 1 and picropolinone 2, thereby establishing the absolute stereochemistry of these two neoclerodane-type diterpenes. 相似文献
44.
J.L. Valverde A. de Lucas F. Dorado A. Romero P.B. García 《Journal of molecular catalysis. A, Chemical》2005,230(1-2):23-28
Adsorption on Cu ion-exchanged titanium pillared clay (Cu-Ti-PILC) was investigated by in situ infrared spectroscopy to provide insight into the reaction intermediates present in the selective catalytic reduction (SCR) of NO by propene in the presence of oxygen. The NO/O2 adsorption produced different nitrate species due to the presence of terminal and bridged Cu2+–OH groups. These nitrates evolved into N2 and N2O in small amounts once the NO catalytic cycle was finished. It can be concluded that the Cu2+–OH groups reacted with the nitro group, thus forming nitrates. C3H6 adsorption was higher and stronger than NO adsorption on the active sites of the catalyst. C3H6 reacted in the active site producing hydrocarbon intermediates (an organic nitro compound and acetate), which were responsible for the NO reduction. 相似文献
45.
Clodoaldo Valverde Rafael S. Vinhal Luiz F. N. Naves Jean M. F. Custdio Basílio Baseia Heibbe Cristhian B. de Oliveira Caridad N. Perez Hamilton B. Napolitano Francisco A. P. Osrio 《Molecules (Basel, Switzerland)》2022,27(8)
A novel 4(1H) quinolinone derivative (QBCP) was synthesized and characterized with single crystal X-ray diffraction. Hirshfeld surfaces (HS) analyses were employed as a complementary tool to evaluate the crystal intermolecular interactions. The molecular global reactivity parameters of QBCP were studied using HOMO and LUMO energies. In addition, the molecular electrostatic potential (MEP) and the UV-Vis absorption and emission spectra were obtained and analyzed. The supermolecule (SM) approach was employed to build a bulk with 474,552 atoms to simulate the crystalline environment polarization effect on the asymmetric unit of the compound. The nonlinear optical properties were investigated using the density functional method (DFT/CAM-B3LYP) with the Pople’s 6-311++G(d,p) basis set. The quantum DFT results of the linear polarizability, the average second-order hyperpolarizability and the third-order nonlinear susceptibility values were computed and analyzed. The results showed that the organic compound (QBCP) has great potential for application as a third-order nonlinear optical material. 相似文献
46.
47.
N. Valverde und C. Wagner 《Colloid and polymer science》1977,255(10):1023
Ohne Zusammenfassung 相似文献
48.
J. C. Valverde 《Acta Mathematica Hungarica》2000,88(1-2):113-121
One way to deal with bifurcations in the theory of dynamical systems is to find some normal forms of the system, that is, doing some changes of coordinates, the system can be led to a similar form to that given for the normal forms. But usually it is a complicated problem to elucidate if the truncated normal form of the system is (locally) topologically conjugated to the normal one. Here, we provide a way to avoid this problem when we study bifurcations, through the consideration of the surface of the fixed points which allows us to generalize the non-degenerated conditions of certain bifurcations to appear. 相似文献
49.
50.
Inside Back Cover: First Step Towards a Devil's Staircase in Spin‐Crossover Materials (Angew. Chem. Int. Ed. 30/2016)
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