1,721,004 research outputs found
Ulteriori datazioni radiometriche per le alluvioni della piana costiera del Torrente Conca (Romagna).
No full textTerrace fluvial deposits from the middle basin of Cesano River (Northern Marche Apennines): reconnaissance study and radiometric constraints on their age.
No full textRicerca del punto di rottura di due regressioni per la determinazione del punto di deflessione della frequenza cardiaca al variare della velocita
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A new MO-VB approach for the determination of intermolecular forces. Theory and application to the He2, He-CH4 and He-H2O systems
No full textWe present the improvement of a previously developed strategy for the evaluation of intermolecular forces.
The approach defines a variational VB (valence bond) wave function, consisting of single and double excitations
from the SCF-MI (self-consistent field for molecular interactions) determinant. The central idea of the method
is the determination of optimal virtual orbitals, to contract the virtual space spanned by all singly and doubly
excited localized configurations, by means of an iterative optimization procedure. The performance of the
strategy is tested by comparison with results where the full virtual space is considered, and the entire approach
is also compared with more conventional quantum chemical methods. Test calculations on three weakly
interacting complexes, namely, He2, He-CH4, and He-H2O, are presented. Whatever the system studied, we
found an overall agreement between VB, MP4, and CCSD(T) results. The VB well depths estimates are
somewhat larger than MP4 and CCSD(T) ones
Potential energy surface, bound states, and rotational inelastic cross sections of the He-CH4 system: A theoretical investigation
No full textWe determined two potential energy surfaces (PES) for the He-CH4 system by means of MP4 and Valence Bond (VB) calculations. The MP4 potential is similar to the one commonly adopted for this system [U. Buck, K. H. Kohl, A. Kolhase, M. Faubel, and U. Staemmler, Mol. Phys. 55, 1255 (1985)], while the VB PES is slightly more attractive. To evaluate the reliability of these potentials, we investigated the scattering properties by performing close coupling calculations, and concluded that: (i) the available experimental data do not permit the ranking among the PES considered; (ii) some theoretical predictions differ considerably from the experimental data, and these discrepancies cannot entirely be ascribed to the inaccuracy of the ab initio calculations; (iii) the scattering properties at low energy might discriminate between the MP4 and VB potentials
Last-glacial terrace alluvium in the Metauro River basin: some remarks about new radiometric ages.
No full textGeomorphological evolution of the coastal area in N Marche (central Italy) during the late Quaternary.
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