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排序方式: 共有105条查询结果,搜索用时 31 毫秒
81.
Francesca Bonenti Juan Enrique Martínez-Legaz Rossana Riccardi 《Journal of Optimization Theory and Applications》2018,176(3):527-540
We introduce a (possibly infinite) collection of mutually dual nonconvex optimization problems, which share a common optimal value, and give a characterization of their global optimal solutions. As immediate consequences of our general multiduality principle, we obtain Toland–Singer duality theorem as well as an analogous result involving generalized perspective functions. Based on our duality theory, we propose an extension of an existing algorithm for the minimization of d.c. functions, which exploits Toland–Singer duality, to a more general class of nonconvex optimization problems. 相似文献
82.
83.
Mariangela Lopreiato Rossana Cocchiola Susanna Falcucci Martina Leopizzi Michele Cardone Valeria Di Maio Umberto Brocco Valerio D'Orazi Stefano Calvieri Roberto Scandurra Federico De Marco Anna Scotto d'Abusco 《Photochemistry and photobiology》2020,96(1):74-82
The ultraviolet (UV) component of solar radiation is the driving force of life on earth, but it can cause photoaging and skin cancer. In this study, we investigated the effects of the glucosamine-derivative 2-(N-Acetyl)-L-phenylalanylamido-2-deoxy-β-D-glucose (NAPA) on human primary fibroblasts (FBs) stimulated in vitro with environmental levels of UVB radiation. FBs were irradiated with 0.04 J cm−2 UVB dose, which resulted a mild dosage as shown by the cell viability and ROS production measurement. This environmental UVB dose induced activation of MAP kinase ERK 1/2, the stimulation of c-fos and at lower extent of c-jun, and in turn AP-1-dependent up-regulation of pro-inflammatory factors IL-6 and IL-8 and suppression of collagen type I expression. On the contrary, 0.04 J cm−2 UVB dose was not able to stimulate metalloprotease production. NAPA treatment was able to suppress the up-regulation of IL-6 and IL-8 via the inhibition of MAP kinase ERK phosphorylation and the following AP-1 activation, and was able to attenuate the collagen type I down-regulation induced by the UVBs. Taken together, our results show that NAPA, considering its dual action on suppression of inflammation and stimulation of collagen type I production, represents an interesting candidate as a new photoprotective and photorepairing agents. 相似文献
84.
Agnieszka Mroczek Giulia Erre Rossana Taras Serafino Gladiali 《Tetrahedron: Asymmetry》2010,21(15):1921-1927
A synthetic procedure relying on the Friedländer condensation of enantiopure α-amino ferrocenecarboxaldeyde has been devised for the regio-designed elaboration of a pyridine nucleus fused onto the ferrocene scaffold. Three novel bidentate ligands with different pyridine nitrogen donors featuring the [3,2-b]ferrocenopyridine fragment a as the sole chirogenic element have been prepared in enantiopure form through a multi step route involving the diastereoselective deprotonation of a chiral acetal of ferrocenecarboxaldehyde in the stereodetermining step. The ligands were assessed in the Pd-catalyzed allylic alkylation of 1,3-diphenyl-2-propenyl esters with good stereoselectivity. 相似文献
85.
Emilio Scamporrino Rossana Alicata Sebastiano Bazzano Daniele Vitalini Placido Mineo 《Macromolecular Symposia》2004,218(1):21-28
The synthesis of some poly(bisphenol-A)carbonates (PCs) containing hydrophilic porphyrin units as end groups, by thermal treatment of commercial PC and 5,10,15-tri{p[ω-methoxy-poly(oxyethylene)]phenyl}20(p-hydroxy phenyl)porphyrin (I) blends, is reported. A suitable choice of reaction temperature, molar composition and reaction time, allowing the extent of the outer-inner transesterification reactions, leads to a gradual insertion of porphyrin units in the polymer chains. The composition of the obtained materials was inferred by GPC and MALDI-TOF mass spectrometric analysis. 相似文献
86.
Rossana M. S. M. Thiré Taíla O. Meiga Sabrina Dick Leonardo R. Andrade 《Macromolecular Symposia》2007,258(1):38-44
Summary: Chemical modification of polymer surface may potentially be used to create smart materials that can guide cellular adhesion, proliferation and maintenance of specific expression of molecules. The microbial polyester poly (3-hydroxybutyrate) (PHB) has been attracted attention as promising material for applications in tissue engineering. In this work, a wet-chemical method, base ethylenediamine aminolysis, was performed to improve the adhesion of chondrocytes isolated from human articular cartilage to PHB films. The effects of chemical treatment on PHB films was evaluated by following changes in morphology and surface chemical composition using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), respectively. While the effect on cells morphology was studied by scanning electron microscopy (SEM). The treatment with ethylenediamine did not change significantly the morphology of the structures of PHB films surface. However, the roughness of the aminolyzed films was slightly higher. The introduction of nitrogen-containing groups was confirmed by XPS. In vitro experiments indicated that the surface modification did not have toxic effects in cells, since they could adhere and proliferate on modified PHB films. It was observed that long-time treatment improved ability of PHB films to support cell growth, which could be accounted to physicochemical and topological effects. 相似文献
87.
Rossana Chiavacci 《Annali dell'Universita di Ferrara》1981,27(1):35-42
Riassunto In questa nota si dimostra che un morfismo adico fra spazi analitici formali è finito se e solo se è quasi-finito; si dimostra
inoltre un teorema di coerenza delle immagini dirette per morfismi 1-convessi fra spazi analitici formali.
Summary In this paper we prove that an adic morphism between formal analytic spaces is finite if and only if it is quasi-finite; moreover we establish a direct image theorem for 1-convex morphisms between formal analytic spaces.相似文献
88.
Jared V. Goldstone Rossana Del Vecchio Nell V. Blough Bettina M. Voelker 《Photochemistry and photobiology》2004,80(1):52-60
Light absorption by chromophoric dissolved organic matter (CDOM) plays a number of roles in natural waters, including both control of the underwater light field and the initiation of many photochemical reactions. A multicomponent analysis was used to describe the effects of UV and visible radiation on the optical absorption spectra of two natural water samples, a Suwannee River fulvic acid standard (SRFA) and a Delaware Bay water sample. This analysis used a constrained minimization technique to fit independent spectral components to the observed bleaching behavior of the water samples under monochromatic irradiation. Spectra derived from these fits were used to predict the bleaching behavior of both samples under polychromatic irradiation (λ< 320 nm). This approach reproduces the kinetics and spectral behavior of polychromatic photobleaching very well at times <48 h, but underpredicts the bleaching at longer time periods. 相似文献
89.
Giuliana Cardillo Serena Fabbroni Luca Gentilucci Rossana Perciaccante Fabio Piccinelli Alessandra Tolomelli 《Tetrahedron》2004,60(23):5031-5040
An approach to 3-bromo-4-alkyl-6-aryl-5,6-dihydropyridin-2-ones and 3-bromo-5-ethyl-6-aryl-5,6-dihydropyridin-2-ones starting from β,γ-unsaturated α-bromoketenes and imines is reported. The presence of a bromine atom on the double bond allows performing aziridination or bromine displacement with an amine. The reaction gave fused bicyclic N-allyl-aziridines or 3-amino-substituted 5,6-dihydropyridin-2-ones, depending on the substituents on the six-membered ring. 相似文献
90.
TG and DSC investigation of gallstone samples collected from patients submitted to cholecystectomy 总被引:1,自引:0,他引:1
Rossana A. Toscano Dulce M. de A. Melo Maria de F. V. de Moura Robson F. de Farias 《Thermochimica Acta》2004,410(1-2):125-131
In the present work are performed the TG and DSC study of gallstone samples collected from patients submitted to cholecystectomy at the Hospital Universitário Onofre Lopes of Universidade Federal do Rio Grande do Norte, in Natal, Rio Grande do Norte State, Brazil. The gallstone samples were characterized by elemental analysis and infrared spectroscopy. Standard cholesterol was used for all analysis as comparison with the gallstones. Is verified that cholesterol is the main chemical component of all studied gallstone samples. The thermoanalytical study was performed on air and nitrogen atmospheres. The presence of cholesterol as the main chemical component of all gallstone samples is confirmed by TG and DSC results. 相似文献