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61.
62.
Summary Within a framework of general algebra we firstly formulate propositions concerning the connection between irreducibility,
id est the absence of certain types of subalgebrae, and simplicity.
Then we investigate some uniqueness properties of the congruences of certain types of lattices and we apply the general propositions
to algebrae with lattice operations obtaining sufficient conditions for the simplicity of wide classes of such algebrae.
Riassunto In un contesto di algebra generale noi formuliamo dapprima proposizioni concernenti la connessione tra irriducibilità, cioè l’assenza di certi tipi di sottoalgebre, e semplicità. In seguito investighiamo alcune proprietà di unicità delle conseguenze di certi tipi di reticoli e applichiamo le proposizioni generali ad algebre con operazioni di reticolo ottenendo condizioni sufficienti per la semplicità di ampie classi di tali algebre.相似文献
63.
Terzi F Seeber R Pigani L Zanardi C Pasquali L Nannarone S Fabrizio M Daolio S 《The journal of physical chemistry. B》2005,109(41):19397-19402
In this article the adsorption of 3-methylthiophene on planar and nanoparticle Au surfaces is investigated. The resulting systems are compared with a benchmark system based on 1-decanethiol. The characterization data collected evidence the formation of a packed 3-methylthiophene SAM on the planar surface. In particular, spectroscopic investigations suggest that 3-methylthiophene aromatic system is not adsorbed on the surface through the pi-electron system but rather through the S atom alone. On the other hand, the behavior of 3-methylthiophene on nanoparticle surfaces is notably different from that of the alkanethiol. Only a limited fraction of the surface of Au nanoparticles results to be actually coated after purification; this notwithstanding, the nanoparticle growth seems to be strongly influenced by the presence of such a labile encapsulating agent. 相似文献
64.
Luigi?C.?BerselliEmail author Renato?ManfrinEmail author 《Journal of Evolution Equations》2004,4(2):193-211
In this paper we study some criteria for the full (space-time) regularity of weak
solutions to the Navier-Stokes equations. In particular, we generalize some
classical and very recent criteria involving the velocity, or its
derivatives. More specifically, we show with elementary tools that if a weak
solution, or its vorticity, is small in appropriate Marcinkiewicz spaces, then it
is regular. 相似文献
65.
F. Selleri 《Foundations of Physics Letters》2003,16(1):71-82
Transformations of space and time, depending on a synchronisation parameter e
1, indicate the existence of a privileged inertial system S
0. The Lorentz transformations are obtained for a particular e
10. No classical experiment on relativity is expected to depend on the choice of e
1. We show, consistently with expectations, that the result of the Fizeau experiment is explained equally well by theories adopting different values of e
1. In previous papers we showed that if accelerated reference frames are considered only e
1=0 remains possible. 相似文献
66.
Zhang J Frankevich V Knochenmuss R Friess SD Zenobi R 《Journal of the American Society for Mass Spectrometry》2003,14(1):42-50
The mechanisms of the reduction of Cu(II) in matrix-assisted laser desorption/ionization mass spectrometry (MALDI) are studied. In MALDI mass spectra, ions cationized by copper mostly contain Cu(I) even if Cu(II) salts are added to the sample. It was found that Cu(II) was reduced to Cu(I) by gas-phase charge exchange with matrix molecules, which is a thermodynamically favorable process. Under some conditions, large amounts of free electrons are present in the plume. Cu(II) can be even more efficiently reduced to Cu(I) by free electron capture in the gas phase. The matrices studied in this work are nicotinic acid, dithranol, and 2,5-dihydroxybenzoic acid. 相似文献
67.
Enzymatic resolution of bicyclic 1-heteroarylamines using Candida antarctica lipase B 总被引:1,自引:0,他引:1
Skupinska KA McEachern EJ Baird IR Skerlj RT Bridger GJ 《The Journal of organic chemistry》2003,68(9):3546-3551
Candida antarctica lipase B has been used to kinetically resolve a structurally diverse series of bicyclic 1-heteroaryl primary amines by enantioselective acetylation. High yields of either enantiomer could be obtained with excellent enantioselectivity (90-99% ee), while the undesired enantiomer could, in some cases, be recycled by thermal racemization. The absolute stereochemistry of the products was confirmed by an X-ray crystal structure. 相似文献
68.
Pollutants removal in two vertical flow experimental wetlands receiving pre-treated municipal wastewater was investigated. Laboratory investigations using microcosms were also carried out in order to identify key processes regulating pollutants removal. Results obtained from experimental wetlands seem to confirm the ability of a single stage installation, where nitrification and denitrification processes are jointly optimised using a gravel medium, always wet but not saturated with water. Results obtained from microcosm investigations show the prominent role of O2 supply, of microbial activity and of bio-available C from vegetal metabolism in the nitrogen removal. 相似文献
69.
The hydrogen bonds formed between the hydroperoxyl radical and formic, acetic, and trifluoroacetic acids were characterized using geometric, energetic, and electronic parameters through calculations done with the UB3LYP/6-311++G (3df,3pd) and UB3LYP/EPR-III methods. The wave functions were analyzed through the natural bond orbital, natural steric analysis, natural resonance theory, and atoms in molecules methods. The energy decomposition method proposed by Xantheas was used. The vibrational frequencies and the intensity of the O-H stretching bands, as well as the spin densities, were compared with experimental evidence. The results allowed the characterization of the hydrogen bonds formed in the complexation of the acids with the hydroperoxyl radical. Complexation led to significant alterations in the equilibrium geometry of the monomers. Energetic analysis proved that the studied complexes are stable and allowed the understanding of the effect of the electron-donating and electron-withdrawing groups in their stabilization. The alterations in the electronic structure of the monomers after complexation led to an increase in the resonance of the carboxyl group, which can be partially attributed to the hydrogen bond. 相似文献