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排序方式: 共有481条查询结果,搜索用时 31 毫秒
461.
Ennio De Giorgi 《Annali di Matematica Pura ed Applicata》1955,40(1):371-377
Sunto Si dimostra il teorema di unicità enunciato nelle prime righe.
A Mauro Picone nel suo 70mo compleanno.
Lavoro eseguito presso l'Istituto Nazionale per le Applicazioni del Calcolo. 相似文献
462.
The influence of superplasticizers on the first steps of tricalcium silicate hydration studied by NMR techniques 总被引:1,自引:0,他引:1
Pirazzoli I Alesiani M Capuani S Maraviglia B Giorgi R Ridi F Baglioni P 《Magnetic resonance imaging》2005,23(2):277-284
The influence of superplasticizer sulfonated naphthalene formaldehyde (SNF) on the hydration process of tricalcium silicate (C3S) paste was investigated by (1)H nuclear magnetic resonance spin-spin and spin lattice relaxation times. The addition of SNF superplasticizer to C3S paste clearly affects the morphology and growth rates of the hydration products, mainly by increasing the dormant period length, which lasts for several hours more than in conventional C3S hydrated paste, while reducing the acceleration period length. The relaxation data indicated that a pronounced delay occurs in the C3S hardening when sulfonated polymers are added to the makeup water. For all the analyzed samples, prepared with a water-to-C3S ratio of 0.4, the decay of the echo magnetization has been fitted by adopting both a monoexponential and a biexponential relaxation model in order to evaluate the contributions from water in different regimes of hydration. 相似文献
463.
Cecchettini A Locci MT Masetti M Fausto AM Gambellini G Mazzini M Giorgi F 《Micron (Oxford, England : 1993)》2003,34(1):39-48
Vitellin polypeptides are proteolytically processed in ovarian follicles and embryos of the stick insect Carausius morosus. Data show that vitellin polypeptide A(3) of 54kDa is processed to yield polypeptide A(3)(*) of about 48kDa upon completion of ovarian development, whereas vitellin polypeptide A(2) of 90kDa yields polypeptide E(9) during embryonic development. As vitellin polypeptides are processed, polypeptides A(3)(*) and E(9) are transferred from the yolk granules to the cytosolic space of the vitellophages and start to express a ubiquitin reactivity. At the confocal microscope, anti-ubiquitin antibodies label specifically numerous small yolk granules and the cytosolic space of vitellophages. During embryonic development, ubiquitin carrying granules undergo acidification in much the same way as larger yolk granules. However, only these latter organelles are capable of converting a latent cysteine pro-protease into an active yolk protease upon acidification of their luminal space. These data are interpreted as indicating that ubiquitin-like polypeptides are restricted to small granules throughout ovarian and embryonic development, and that vitellin cleavage products are ubiquitinated following acidification of large yolk granules and transfer to the cytosolic space of the vitellophages. 相似文献
464.
A. Passaseo V. Tasco I. Tarantini M. De Giorgi M. T. Todaro M. De Vittorio R. Cingolani 《Physica E: Low-dimensional Systems and Nanostructures》2004,23(3-4):390
This work explores the conditions to obtain the extension of the PL emission beyond 1.3 μm in InGaAs quantum dot (QD) structures growth by MOCVD. We found that, by controlling the In incorporation in the barrier embedding the QDs, the wavelength emission can be continuously tuned from 1.25 μm up to 1.4 μm at room temperature. However, the increase in the overall strain of the structures limits the possibility to increase the maximum gain in the QD active device, where an optical density as high as possible is required. By exploring the kinetics of QD surface reconstruction during the GaAs overgrowth, we are able to obtain, for the first time, emission beyond 1.3 μm from InGaAs QDs grown on GaAs matrix. The wavelength is tuned from 1.26 μm up to 1.33 μm and significant improvements in terms of line shape narrowing and room temperature efficiency are obtained. The temperature-dependent quenching of the emission efficiency is reduced down to a factor of 3, the best value ever reported for QD structures emitting at 1.3 μm. 相似文献
465.
E. L. Andronikashvili G. M. Mrevlishvili G. Sh. Japaridze V. M. Sokhadze 《International journal of quantum chemistry》1979,16(2):367-377
Methods for determining the thermal measurements of biological objects have found ever increasing application in biology. This paper analyzes the temperature dependence of the heat capacity of biopolymer solutions between 4–400°K. Four distinct temperature regions were discovered, and experiments on these temperature intervals are given. 相似文献
466.
High-energy-neutron (E #62; 1 MeV) irradiation of the A15 phase, Mo0.4Tc0.6, to a fluence of 1.9 × 1020 neutrons/cm2 resulted in only a slight decrease in the superconducting transition temperature (13.4 to 13.1 K). This is in sharp contrast to the results reported for comparable irradiations of high Tc, Nb-based A15 compounds. The results are discussed in terms of the nature of the B atom in the A3B structure and related to the superconducting properties of an A2 type bcc phase of the same composition. 相似文献
467.
From an extrapolation of threshold π+ electroproduction data combined with a kinematical constraint at an unphysical point, we derive the value of the pion form factor at a time-like value of the momentum transfer k2π 1 fm−2. The result is Fπ(k2π) = 1.19 ± 0.1. From this value, using a twice subtracted dispersion relation, we obtain rπ 0.98 ± 0.24 fm. 相似文献
468.
A.S. Clough C.I. Beard D.V. Bugg J.A. Edgington J. Hall K. Bos J.C. Kluyver R.A. Kunne L. Linssen R. Birsa F. Bradamante S. Dalla Torre-Colautti M. Giorgi A. Martin A. Penzo P. Schiavon A. Villari S. Degli-Agosti D. Rapin 《Physics letters. [Part B]》1984,146(5):299-302
Measurements are reported of p?p total cross sections from 388 to 599 MeV/c in small momentum steps. Statistical errors are typically ±0.4%and the normalisation uncertainty is ±0.7%. There is no evidence for the “S-meson”. 相似文献
469.
Myriam Roy Veronika Berezhnaia Marco Villa Nicolas Vanthuyne Michel Giorgi Jean‐Valre Naubron Salom Poyer Valrie Monnier Laurence Charles Yannick Carissan Denis Hagebaum‐Reignier Jean Rodriguez Marc Gingras Yoann Coquerel 《Angewandte Chemie (International ed. in English)》2020,59(8):3264-3271
We report a molecular design and concept using π‐system elongation and steric effects from helicenes surrounding a triphenylene core toward stable chiral polycyclic aromatic hydrocarbons (PAHs) with a maximal π‐distortion to tackle their aromaticity, supramolecular and molecular properties. The selective syntheses, and the structural, conformational and chiroptical properties of two diastereomeric large multi‐helicenes of formula C90H48 having a triphenylene core and embedding three [5]helicene units on their inner edges and three [7]helicene units at their periphery are reported based on diastereoselective and, when applicable, enantiospecific Yamamoto‐type cyclotrimerizations of racemic or enantiopure 9,10‐dibromo[7]helicene. Both molecules have an extremely distorted triphenylene core, and one of them exhibits the largest torsion angle recorded so far for a benzene ring (twist=36.9°). 相似文献
470.
Joana Domingues Nicole Bonelli Rodorico Giorgi Piero Baglioni 《Applied Physics A: Materials Science & Processing》2014,114(3):705-710
Semi-interpenetrating (IPN) poly (2-hydroxyethyl methacrylate)/polyvinylpyrrolidone hydrogels were synthesized and used for the removal of adhesives from the back of canvas paintings. The high water retention capability and the specific mechanical properties of these gels allow the safe cleaning of water-sensitive artifacts using water-based detergent systems. The cleaning action is limited to the contact area and layer-by-layer removal is achieved while avoiding water spreading and absorption within water-sensitive substrates, which could lead, for example, to paint detachment. The use of these chemical gels also avoids leaving residues over the treated surface because the gel network is formed by covalent bonds that provide high mechanical strength. In this contribution, the physicochemical characterization of semi-IPN chemical hydrogels is reported. The successful application of an o/w microemulsion confined in the hydrogel for the removal of adhesives from linen canvas is also illustrated. 相似文献