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21.
Ermanno Marchionna 《Annali di Matematica Pura ed Applicata》1954,37(1):265-290
Sunto Si dimostra che: data in Sr-1 un'ipersuperficie generale F(x1, x2, …, xr-1)=0 e su di essa una varietà D che sia di diramazione per una funzione u(x1, x2, …, xr-1) — definita da un'ipersuperficie generale Aμ(x1, x2, …, xr-1, u) =0 d'ordine μ >4 (di Sr) — qualunque funzione u' dei punti di F diramata dalla D è birazionalmente identica alla u. La dimostrazione viene ricondotta
al caso delle curve multiple, in virtù di un criterio d'identità qui appositamente stabilito, ed è basata sulla costruzione
della Riemanniana di una curva multipla generale. 相似文献
22.
Clelia Dispenza Maurizio Leone Caterina Lo Presti Fabio Librizzi Valeria Vetri Giuseppe Spadaro 《Macromolecular Symposia》2007,247(1):303-310
Nanocomposites of inherently conductive polyaniline (PANI) within a highly hydrophilic polyvinyl alcohol (PVA) based hydrogel have been produced by coupling a conventional dispersion chemical oxidative polymerization to a subsequent high energy irradiation step, in order to convert the polymer stabilizing the aqueous dispersion, namely the PVA, into a highly water swollen hydrogel incorporating the PANI particles. The incorporation of the electroactive and “pH-sensitive” polymer into a transparent and highly permeable hydrogel matrix has been pursued as a route to the development of a novel class of potentially biocompatible, smart hydrogels that can respond to changes of the surrounding environment with measurable changes in their optical properties. Absorption spectra show that the optical absorption bands typical of PANI, known to be reversibly affected by changes of the polymer oxidation state or pH or both, are well preserved in the PVA hydrogels. Even more interestingly, fluorescence is observed from the nanoparticles of PANI in its inherently conductive form, whose intensity is strongly affected by changes of pH. This has enhanced the importance of this material to a large extent from both a scientific and a practical point of view. 相似文献
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Wang X Beckmann PA Mallory CW Rheingold AL DiPasquale AG Carroll PJ Mallory FB 《The Journal of organic chemistry》2011,76(13):5170-5176
The rotation barriers for 10 different methyl groups in five methyl-substituted phenanthrenes and three methyl-substituted naphthalenes were determined by ab initio electronic structure calculations, both for the isolated molecules and for the central molecules in clusters containing 8-13 molecules. These clusters were constructed computationally using the carbon positions obtained from the crystal structures of the eight compounds and the hydrogen positions obtained from electronic structure calculations. The calculated methyl rotation barriers in the clusters (E(clust)) range from 0.6 to 3.4 kcal/mol. Solid-state (1)H NMR spin-lattice relaxation rate measurements on the polycrystalline solids gave experimental activation energies (E(NMR)) for methyl rotation in the range from 0.4 to 3.2 kcal/mol. The energy differences E(clust) - E(NMR) for each of the ten methyl groups range from -0.2 kcal/mol to +0.7 kcal/mol, with a mean value of +0.2 kcal/mol and a standard deviation of 0.3 kcal/mol. The differences between each of the computed barriers in the clusters (E(clust)) and the corresponding computed barriers in the isolated molecules (E(isol)) provide an estimate of the intermolecular contributions to the rotation barriers in the clusters. The values of E(clust) - E(isol) range from 0.0 to 1.0 kcal/mol. 相似文献
27.
Sabina Alessi Alberto Spinella Eugenio Caponetti Clelia Dispenza Giuseppe Spadaro 《Radiation Physics and Chemistry》2012,81(9):1328-1331
In this paper the network structure of e-beam cured DGEBF based epoxy resins is investigated. Two epoxy systems, having different reactivity and cured in different process conditions, were analyzed through solid state NMR spectroscopy. The analysis shows that the more reactive system has higher cross-linking density and higher uniformity of network distribution. Similar information were obtained, in a previous work, on the same systems through dynamic mechanical thermal analysis. It is worth noting that unlike DMTA tests, which interfere with the molecular structure of the analyzed material, due to the heating during the analysis itself, more reliable information, without any artefact, are obtained by solid state NMR, carried out at constant room temperature. 相似文献
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Cesarina Tibiletti Marchionna 《Milan Journal of Mathematics》1999,69(1):193-236
Conferenza tenuta il giorno 18 Dicembre 2000 相似文献
30.
Ermanno Marchionna 《Milan Journal of Mathematics》1988,58(1):285-307
On the complete intersections varieties.
Lavoro eseguito nell'ambito dei Gruppi di Ricerca del M.P.I. e del C.N.R. 相似文献
Lavoro eseguito nell'ambito dei Gruppi di Ricerca del M.P.I. e del C.N.R. 相似文献