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51.
Marco Degiovanni 《Annali di Matematica Pura ed Applicata》1990,156(1):37-71
Summary A class of extended real valued functionals, already considered for evolution problems, is studied. The set where the functional is finite is proved to be an absolute neighborhood extensor. Applications to critical point theory, involving Ljusternik-Schnirelman category and cohomological index, are shown. The stability under -convergence of the homotopical type of the sublevels of the functional is also treated.The author is a member of theGruppo Nazionale per l'Analisi Funzionalc e le sue Applicazioni (C.N.R.). 相似文献
52.
Vaslow DF Wilson DG Rowe B Wilson MA Bianco JA 《IEEE transactions on medical imaging》1989,8(4):313-321
Parallel-hole collimators of varying design are discussed, using the display signal-to-noise ratio of R.F. Wagner et al. (Med. Phys., vol.6, p.83-94, 1979) to obtain contrast-detail diagrams and analytical expressions for the signal-to-noise ratio in SPECT (single-photon-emission computed tomography). It is concluded: (1) that the detectability of deeply embedded small objects (more than ~10 cm deep) may be improved only slightly by improvements in the resolution and geometric efficiency of parallel-hole collimators; (2) that a long-bore collimator outperforms a low-energy general-purpose collimator for objects smaller than ~2 cm, but only to a minor degree; and (3) that for improvement of small object detectability by SPECT, the most fruitful technological pursuit would probably involve development of focused collimators. 相似文献
53.
Dupieux P Alard JP Augerat J Babinet R Bastid N Brochard F Charmensat P De Marco N Fanet H Fodor Z Fraysse L Girard J Gorodetzky P Gosset J Laspalles C Lemaire MC L'Hôte D Lucas B Marroncle J Montarou G Parizet MJ Poitou J Qassoud D Racca C Schimmerling W 《Physics letters. [Part B]》1988,200(1-2):17-21
Proton-proton small angle correlations have been measured in neon-nucleus collisions, using the 4 pi detector Diogene, at 400 and 800 MeV per nucleon incident energies. Values of the size of the emitting region are obtained by comparison with the Koonin formula, taking into account the biases of the apparatus. The dependence of the density on target mass and incident energy is also analysed. 相似文献
54.
G. Lo Bianco K. P. Schmittgen K. O. Zell P. v. Brentano 《Zeitschrift für Physik A Hadrons and Nuclei》1989,332(1):103-104
The ratio of the B(E2) values for the 0 1 + → 2 1 + transitions in138Ce and142Ce was measured by Coulomb excitation with α-particles. From the known value of the transition probability in142Ce it results: B(E2,138Ce, 0 1 + → 2 1 + =0.45 +/?0.03 e2 b 2 相似文献
55.
56.
Henriques ES Floriano WB Reuter N Melo A Brown D Gomes JA Maigret B Nascimento MA Ramos MJ 《Journal of computer-aided molecular design》2001,15(4):309-322
We present the search for a new model of -factor XIIa, a blood coagulation enzyme, with an unknown experimental 3D-structure. We decided to build not one but three different models using different homologous proteins as well as different techniques and different modellers. Additional studies, including extensive molecular dynamics simulations on the solvated state, allowed us to draw several conclusions concerning homology modelling, in general, and -factor XIIa, in particular. 相似文献
57.
Poschalko A Lancelot N Marin J Larras V Limal D Elbayed K Raya J Piotto M Briand JP Guichard G Bianco A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(18):4532-4537
A novel resin called DEUSS (perdeuterated poly(oxyethylene)-based solid support) has been prepared by anionic polymerization of deuterated [D4]ethylene oxide, followed by cross-linking with deuterated epichlorohydrin. DEUSS can be suspended in a wide range of solvents including organic and aqueous solutions, in which it displays a high swelling capacity. As measured by proton HRMAS of the swollen polymer, the signal intensity of the oxyethylene protons is reduced by a factor of 110 relative to the corresponding nondeuterated poly(oxyethylene)poly(oxypropylene) (POEPOP) resin, thus facilitating detailed HRMAS NMR studies of covalently linked molecules. This 1H NMR invisible matrix was used for the solid-phase synthesis of peptides, oligoureas, and a series of amides as well as their characterization by HRMAS NMR spectroscopy. On-bead NMR spectra of high quality and with resolution comparable to that of liquid samples were obtained and readily interpreted. The complete absence of the parasite resin signals will be of great advantage, for example, for the optimization of multistep solid-phase stereoselective reactions, and for the conformational study of resin-bound molecules in a large variety of solvents. 相似文献
58.
Tessore F Roberto D Ugo R Pizzotti M Quici S Cavazzini M Bruni S De Angelis F 《Inorganic chemistry》2005,44(24):8967-8978
Coordination of 4'-(C6H4-p-X)-2,2':6',2'-terpyridines [X = NO2, NBu2, (E)-CH=CH-C6H4-p-NBu2, (E,E)-(CH=CH)2-C6H4-p-NMe2] to Zn(II), Ru(III), and Ir(III) metal centers induces a significant enhancement of the absolute value of the second-order nonlinear optical (NLO) response of the terpyridine, measured by means of both electric field induced second harmonic generation and solvatochromic methods. By varying the nature of the metal center, the enhanced second-order NLO response shifts from positive to negative. Such a shift is controlled by electronic charge-transfer transitions, such as metal-to-ligand or ligand-to-metal transitions, in addition to the intraligand charge transfer. The enhancement generated by coordination is also controlled by the chelation effect and by fine-tuning of the ancillary ligands. 相似文献
59.
Lucarini M Franchi P Pedulli GF Gentilini C Polizzi S Pengo P Scrimin P Pasquato L 《Journal of the American Chemical Society》2005,127(47):16384-16385
ESR spectroscopy has been used to study the interaction of para-pentylbenzyl hydroxyalkyl nitroxide with the monolayer of water-soluble protected gold clusters having a core diameter ranging from 1.6 to 5.3 nm. The solubilization of the nitroxide probe in the more hydrophobic environment of the monolayer strongly depends on the size of the gold core. In particular, the partition equilibrium constant increases as the nanoparticle diameter decreases. These results have been attributed to the different packing of the chains in the monolayer resulting from the different radius of curvature of the investigated nanoparticles. This represents, to the best of our knowledge, the first report demonstrating that the core size of metallic nanoparticles affects the solvating properties of the protective organic monolayer. 相似文献
60.
The direct flow injection potentiometric (FIP) analysis of phosphate in hydroponic nutrient solution has been carried out using a cobalt-wire ion-selective electrode (ISE). Synthetic hydroponic nutrient solution, commercial hydroponic nutrient solution and working hydroponic farm nutrient solution were analysed for phosphate using the FIP technique. It is shown that FIP results compare favourably to standard methods of analysis such as spectrophotometry and indirect photometric ion-pair chromatography. Reproducible FIP response curves with a slope of −(47.57±0.03) mV per decade and intercept of −(169.7±0.1) mV were obtained for four separate calibrations in the concentration range 5.0×10−4–1.0×10−2 M H2PO4−. Anion corrections for interferences by Cl−, NO3− and SO42− were applied to all samples using the selectivity coefficients determined independently using a fixed interference method. Nevertheless, it was found that anion corrections were not necessary, as the deviations fell within the bounds of experimental error for the cobalt-wire ISE technique (i.e.±2–5% R.S.D.). The proposed FIP method enables the direct determination of phosphate in hydroponic nutrient solutions. 相似文献