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排序方式: 共有189条查询结果,搜索用时 15 毫秒
61.
Giuseppe Werber Francesco Buccheri Nicolb Vivona Manila Gentile 《Journal of heterocyclic chemistry》1977,14(8):1433-1434
The behaviour of phenylglyoxal thiosemicarbazones towards aqueous sodium hydroxide have been studied. Examples of addition compounds, 5-hydroxy-5-phenyl-2,3,4,5-tetrahydro-1,2,4-triazine-3-thiones, are reported. 相似文献
62.
A study of the crystallographic, optical, and thermochemical properties of hydrazonium tartrate and deuterated hydrazonium tartrate enantiomers is described. Crystals of the enantiomers are orthorhombic with a tetramolecular cell. The space group is P212121 with the lattice parameters a0 = 7.640 ± 0.002 Å, b0 = 13.441 ± 0.003 Å, and c0 = 7.029 ± 0.002 Å. No change in lattice parameters is observed on deuteration. Optical second harmonic powder analysis shows the crystals to be phase matchable at 1.06 μm with d2ω = 11 d2ωα-SiO2. The optical nonlinearity being unaffected by deuterium substitution is attributed to the nonlinear electronic polarizability of the hydrogen bonds. Crystals are transparent from 239 nm to 1.61 μm. Deuteration shifts the long wavelength cutoff to 2.07 μm, without affecting the band edge. 相似文献
63.
PMMA based nanocomposites filled with calcium carbonate nanoparticles (CaCO3) have been prepared by in situ polymerization approach. In order to improve inorganic nanofillers/polymer compatibility, PBA chains have been grafted onto CaCO3 nanoparticle surface. Morphological analysis performed on nanocomposite fractured surfaces has revealed that the CaCO3 modification induces homogeneous and fine dispersion of nanoparticles into PMMA as well as strong interfacial adhesion between the two phases. Mechanical tests have shown that both unmodified and modified CaCO3 are responsible for an increase of the Young's Modulus, whereas only PBA-grafted nanoparticles allow to keep unchanged impact strength, strongly deteriorated by adding unmodified CaCO3. Finally, the presence of CaCO3 nanoparticles significantly improves the abrasion resistance of PMMA also modifying its wear mechanism. 相似文献
64.
We correct a Feynman diagram presented in the paper ‘Heavy neutral gauge bosons at the LHC in an extended MSSM’, published in Nuclear Physics B 866 (2013) 293. 相似文献
65.
Candeloro P Tirinato L Malara N Fregola A Casals E Puntes V Perozziello G Gentile F Coluccio ML Das G Liberale C De Angelis F Di Fabrizio E 《The Analyst》2011,136(21):4402-4408
Microinjection techniques and Raman spectroscopy have been combined to provide a new methodology to investigate the cytotoxic effects due to the interaction of nanomaterials with cells. In the present work, this novel technique has been used to investigate the effects of Ag and Fe(3)O(4) nanoparticles on Hela cells. The nanoparticles are microinjected inside the cells and these latter ones are probed by means of Raman spectroscopy after a short incubation time, in order to highlight the first and impulsive mechanisms developed by the cells to counteract the presence of the nanoparticles. The results put in evidence a different behaviour of the cells treated with nanoparticles in comparison with the control cells; these differences are supposed to be generated by an emerging oxidative stress due to the nanoparticles. The achieved results demonstrate the suitability of the proposed method as a new tool for nanotoxicity studies. 相似文献
66.
Prof. Andrea Cappelli Dr. Giorgio Grisci Dr. Marco Paolino Dr. Federica Castriconi Dr. Germano Giuliani Prof. Alessandro Donati Dr. Stefania Lamponi Dr. Raniero Mendichi Dr. Antonella Caterina Boccia Dr. Filippo Samperi Dr. Salvatore Battiato Dr. Eugenio Paccagnini Dr. Mariangela Gentile Dr. Mariano Licciardi Prof. Gaetano Giammona Prof. Salvatore Vomero 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(29):9710-9721
Two novel benzofulvene monomers bearing propargyl or allyl groups have been synthesized by means of readily accessible reactions, and were found to polymerize spontaneously by solvent removal, in the apparent absence of catalysts or initiators, to give the corresponding polybenzofulvene derivatives bearing clickable propargyl or allyl moieties. The clickable propargyl and allyl groups were exploited in appropriate click reactions to develop a powerful and versatile “grafting onto” synthetic methodology for obtaining tailored polymer brushes. 相似文献
67.
The effect of delayed feedback on the dynamics of a scalar map is studied by using a frequency-domain approach. Explicit conditions for the occurrence of period-doubling and Neimark-Sacker bifurcations in the controlled map are found analytically. The appearance of a 1:2 resonance for certain values of the delay is also formalized, revealing that this phenomenon is independent of the system parameters. A detailed study of the well-known logistic map under delayed feedback is included for illustration. 相似文献
68.
Livia Corsi Guido Gentile Michela Procesi 《Communications in Mathematical Physics》2011,302(2):359-402
The KAM theorem for analytic quasi-integrable anisochronous Hamiltonian systems yields that the perturbation expansion (Lindstedt
series) for any quasi-periodic solution with Diophantine frequency vector converges. If one studies the Lindstedt series by
following a perturbation theory approach, one finds that convergence is ultimately related to the presence of cancellations
between contributions of the same perturbation order. In turn, this is due to symmetries in the problem. Such symmetries are
easily visualised in action-angle coordinates, where the KAM theorem is usually formulated by exploiting the analogy between
Lindstedt series and perturbation expansions in quantum field theory and, in particular, the possibility of expressing the
solutions in terms of tree graphs, which are the analogue of Feynman diagrams. If the unperturbed system is isochronous, Moser’s
modifying terms theorem ensures that an analytic quasi-periodic solution with the same Diophantine frequency vector as the
unperturbed Hamiltonian exists for the system obtained by adding a suitable constant (counterterm) to the vector field. Also
in this case, one can follow the alternative approach of studying the perturbation expansion for both the solution and the
counterterm, and again convergence of the two series is obtained as a consequence of deep cancellations between contributions
of the same order. In this paper, we revisit Moser’s theorem, by studying the perturbation expansion one obtains by working
in Cartesian coordinates. We investigate the symmetries giving rise to the cancellations which makes possible the convergence
of the series. We find that the cancellation mechanism works in a completely different way in Cartesian coordinates, and the
interpretation of the underlying symmetries in terms of tree graphs is much more subtle than in the case of action-angle coordinates. 相似文献
69.
F. Bonetto G. Gallavotti G. Gentile V. Mastropietro 《Communications in Mathematical Physics》1998,192(3):707-736
Under suitable conditions a flow on a torus C
(p)
-close, with p large enough, to a quasi periodic diophantine rotation is shown to be “linearizable”, i.e. conjugable to the quasi periodic rotation, by a map that is analytic in the perturbation size. This result is parallel to
Moser's theorem stating conjugability in class C
(p')
for some p'<p. The extra conditions restrict the class of perturbations that are allowed.
Received: 5 September 1996 / Accepted: 4 August 1997 相似文献
70.
Joel Hagman Luigi Gentile Christian Moestrup Jessen Manja Behrens Karl-Erik Bergqvist Ulf Olsson 《Cellulose (London, England)》2017,24(5):2003-2015
We have characterized the dissolved state of microcrystalline cellulose (MCC) in cold alkali [2.0 M NaOH(aq)] solutions using a combination of small angle X-ray (SAXS) and static light scattering (SLS), \(^1\)H NMR, NMR self-diffusion, and rheology experiments. NMR and SAXS data demonstrate that the cellulose is fully molecularly dissolved. SLS, however, shows the presence of large concentration fluctuations in the solution, consistent with significant attractive cellulose-cellulose interactions. The scattering data are consistent with fractal cellulose aggregates of micrometre size having a mass fractal dimension \(D\sim 1.5\). At 25\(\,^{\circ }\mathrm {C}\) the solution structure remains unchanged on the time scale of weeks. However, upon heating the solutions above 35\(\,^{\circ }\mathrm {C}\) additional aggregation occurs on the time scale of minutes. Decreasing or increasing the NaOH concentration away from the “optimum” 2 M also leads to additional aggregation. This is seen as an increase of the SAXS intensity at lower q values. Addition of urea (1.8 and 3.6 M, respectively) does not significantly influence the solution structure. With these examples, we will discuss how scattering methods can be used to assess the quality of solvents for cellulose. 相似文献