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排序方式: 共有236条查询结果,搜索用时 156 毫秒
41.
Lee KK Benedetti LR Jeanloz R Celliers PM Eggert JH Hicks DG Moon SJ Mackinnon A Da Silva LB Bradley DK Unites W Collins GW Henry E Koenig M Benuzzi-Mounaix A Pasley J Neely D 《The Journal of chemical physics》2006,125(1):014701
Laser-driven shock compression of samples precompressed to 1 GPa produces high-pressure-temperature conditions inducing two significant changes in the optical properties of water: the onset of opacity followed by enhanced reflectivity in the initially transparent water. The onset of reflectivity at infrared wavelengths can be interpreted as a semiconductor<-->electronic conductor transition in water, and is found at pressures above approximately 130 GPa for single-shocked samples precompressed to 1 GPa. Our results indicate that conductivity in the deep interior of "icy" giant planets is greater than realized previously because of an additional contribution from electrons. 相似文献
42.
Manzoni C Vozzi C Benedetti E Sansone G Stagira S Svelto O De Silvestri S Nisoli M Cerullo G 《Optics letters》2006,31(7):963-965
We produce ultrabroadband self-phase-stabilized near-IR pulses by a novel approach where a seed pulse, obtained by difference-frequency generation of a hollow-fiber broadened supercontinuum, is amplified by a two-stage optical parametric amplifier. Energies up to 20 microJ with a pulse spectrum extending from 1.2 to 1.6 microm are demonstrated, and a route for substantial energy scaling is indicated. 相似文献
43.
We address the use of a single qubit as a quantum probe to characterize the properties of classical noise. In particular, we focus on the characterization of classical noise arising from the interaction with a stochastic field described by Gaussian processes. The tools of quantum estimation theory allow us to find the optimal state preparation for the probe, the optimal interaction time with the external noise, and the optimal measurement to effectively extract information on the noise parameter. We also perform a set of simulated experiments to assess the performances of maximum likelihood estimator, showing that the asymptotic regime, where the estimator is unbiased and efficient, is approximately achieved already after few thousands repeated measurements on the probe system. 相似文献
44.
E Benedetti LS Kocsis KM Brummond 《Journal of the American Chemical Society》2012,134(30):12418-12421
The synthesis and photophysical properties of a series of naphthalene-containing solvatochromic fluorophores are described within. These novel fluorophores are prepared using a microwave-assisted dehydrogenative Diels-Alder reaction of styrene, followed by a palladium-catalyzed cross coupling reaction to install an electron donating amine group. The new fluorophores are structurally related to Prodan. Photophysical properties of the new fluorophores were studied and intriguing solvatochromic behavior was observed. For most of these fluorophores, high quantum yields (60-99%) were observed in methylene chloride in addition to large Stokes shifts (95-226 nm) in this same solvent. As the solvent polarity increased, so did the observed Stokes shift with one derivative displaying a Stokes shift of ~300 nm in ethanol. All fluorophore emission maxima, and nearly all absorption maxima were significantly red-shifted when compared to Prodan. Shifting the absorption and emission maxima of a fluorophore into the visible region increases its utility in biological applications. Moreover, the cyclopentane portion of the fluorophore structure provides an attachment point for biomolecules that will minimize disruptions of the photophysical properties. 相似文献
45.
46.
Dell'Abate M. T. Benedetti A. Sequi P. 《Journal of Thermal Analysis and Calorimetry》2000,61(2):389-396
The possibility to use thermal analysis for a quick characterisation of chemical changes in the organic matter of composted
materials was tested. Nine samples were taken at progressive stages of maturation from the same trench of a fully automated
composting plant. DSC and TG were simultaneously performed in static air conditions on whole ground composts. Progressive
stages in the composting process yielded samples whose DSC traces revealed appreciable modifications in thermal patterns that
agreed well with quantitative data obtained from TG measurements. The ratio between the mass losses associated with the two
main exothermic reactions (R1) showed a good sensitivity in detecting the changes in the level of stabilisation during the
composting process. Thermal methods seem to be a valid comparative method in evaluating the level of bio-transformation of
materials during a composting process.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
47.
Antonello Santini Ettore Benedetti Carlo Pedone Giuseppe Caliendo Vincenzo Santagada Paolo Grieco Elisa Perissutti 《Structural chemistry》1996,7(3):173-181
The solid-state molecular conformations and crystal structures of three analogues of the CP-96,345 molecule, an important nonpeptidic SP antagonist, namely the (±)-2-(3-phenylbenzilidene)-3-(2-benzylamino) quinuclidine, theo-chloro- and theo-methoxy-derivatives, have been determined by X-ray diffusion analyses and refined to finalR values of 0.055, 0.045, and 0.056, respectively. All three molecules in the solid state show the same disposition of the substituents of the double bond and differences in the conformation mainly caused by the need of releasing intramolecular strains and/or nonbonded interactions. The observed molecular structures are compared to the reported solid-state structure of the CP-96,345 and correlated to the biological activity as NK antagonists. 相似文献
48.
49.
Balaz M Holmes AE Benedetti M Rodriguez PC Berova N Nakanishi K Proni G 《Journal of the American Chemical Society》2005,127(12):4172-4173
The preparation and circular dichroic (CD) studies of self-complimentary 8-mer DNA sequences with a porphyrin at the 3' end are presented. Electronic interaction between the two porphyrins (the interchromophoric distance is in the range of 28-40 A), attached to both ends of the double-stranded helix, gives rise to a long-range exciton-coupled CD in the visible region (400-450 nm). The porphyrin chromophores act as sensitive probes of geometrical changes in the DNA backbone and sensitively reflect the double-strand to single-strand transition. This study demonstrates the possibility of using exciton-coupled porphyrin CDs for conformational studies of DNA. 相似文献
50.
Branka Vranei Jelka Tomai Stainslav Smerdel Darko Kantoci Fabio Benedetti 《Helvetica chimica acta》1993,76(4):1752-1758
A novel type of compound that contains a peptide specific for bacterial peptidoglycans (immunomodulatory activity) and an adamantyl residue (antiviral activity) was synthesized. Thus, L -Ala-D -γGln was linked to DL -Gly(Ada) yielding two diasteroisomers 3a and 3b , i.e. ambo-Gly(Ada)-L -Ala-D -γGln (γGln = isoglutamine-4-amino-4-carbamoylbutanoic acid; Ada = adamantyl). The diastereoisomers were easily separated by column chromatography (silica gel) and characterized, but only the use of a stereospecific enzyme led to the assignment of the configuration of the Gly(Ada) moiety in the two diastereoisomers. The cytotoxic effect and antiviral activity of the novel adamantyltripeptides 3a and 3b , observed as the cell survival and the infectivity reduction of the influenza A virus H1N1 and H3N2 strains, respectively, were studied on MDCK cells in vitro. Both 3a and 3b exhibited low cytotoxicity for MDCK cells and reduced the infectivity of the influenza A virus strains, but to a different extent on different Strain. 相似文献