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101.
JM Quintela C Peinador C Veiga L González LM Botana A Alfonso R Riguera 《Canadian Metallurgical Quarterly》1998,6(10):1911-1925
The synthesis of a series of pyridothienopyrimidines and their evaluation as inhibitors or inducers of the release of histamine from rat mast cells is reported. The activity was measured after immunological stimulation with ovoalbumin and chemical stimulation with polymer 48/80 and the drugs adryamicin and vinorelbine. The experiments were carried out with and without preincubation of the stimulus with the cells before addition of the drug. Several pyridothienopyrimidines show inhibitory IC50 values in the range 2-25 microM, indicating they are up to 100 times more potent than cromoglycate (DSCG) and 10 times greater than Ketotifen. Compound 9l is a potent inhibitor in all the conditions tested and shows IC50 = 9-25 microM. Pyridothienopyrimidines 4l and 9e are very strong inducers of histamine release in the immunological (4l, 170-230%) and chemical (9e, 100-150%) assays, respectively. Compounds 4l and 9i are cytotoxic in vitro (IC50 = 0.1-0.2 microgram/mL) against P-388, A-549, HT-29, and MEL-28 tumor cell lines. 相似文献
102.
This article analyses how Internet‐based technologies can help companies to: monitor their business environment online in search of potentially conflictive issues that need to be managed (issues management); to prepare a crisis communications plan that considers the Internet side of today's business landscape (crisis communications planning); to respond adequately to crises should they arise by using all available online tools (crisis response); and to establish appropriate Internet‐based actions once the crisis dies down (post‐crisis). The article also questions whether the traditional one‐way corporate approach and tone is still suitable in the new, more participative, online business environment, or whether companies should use a different tone, language, and attitude when engaging with their audiences on the Internet in a crisis situation. 相似文献
103.
Guillermo Niño-Medina Elizabeth Carvajal-Millán Jaime Lizardi Agustín Rascon-Chu Jorge A. Marquez-Escalante Alfonso Gardea Ana L. Martinez-Lopez Victor Guerrero 《Food chemistry》2009
Water-soluble feruloylated arabinoxylans were extracted from maize processing waste water (nejayote) generated from tortilla-making industries. Nejayote arabinoxylans (NAX) presented a ferulic acid content of 0.23 μg/mg, an arabinose to xylose ratio (A/X) of 0.65, an intrinsic viscosity, [η], of 183 ml/g and a molecular weight (Mw) of 60 kDa. Laccase-induced gels were obtained from 4% (w/v) NAX solution while, at lower concentrations, no gelation was observed. Laccase covalent cross-linking of NAX led to the formation of diferulic (di-FA) and triferulic (tri-FA) acid structures. 4% (w/v) NAX gel presented di-FA and tri-FA contents of 0.02 and 0.01 μg/mg NAX, respectively, and a G′ value of 2 Pa. Recuperation of this gum from a low-value maize by-product could represent a commercial advantage over other gums commonly used in the food industry. 相似文献
104.
Maria Rosaria Corbo Barbara Speranza Alfonso Filippone Amalia Conte Milena Sinigaglia & Matteo Alessandro Del Nobile 《International Journal of Food Science & Technology》2009,44(10):2021-2027
Natural antimicrobial compounds to control the quality decay of a fresh fish burger were studied. In particular, thymol, lemon extract and grape fruit seed extract (GFSE), at 20, 40 and 80 ppm, have been tested against the main spoilage microorganisms inoculated in fish burgers stored at 5 °C. The evolution of mesophilic and psychrotrophic bacteria was also monitored. The sensorial quality decay was determined by means of a panel test, which assessed odour, colour, texture, drip loss and general appearance during the storage period. Results show that all the active substances efficiently slowed down the growth of the spoilage microorganisms. In particular, GFSE was the most efficient against Photobacterium phosphoreum , Shewanella putrefaciens and mesophilic bacteria, whereas thymol was the most efficient against both psychrotrophic bacteria and Pseudomonas fluorescens . Microbial growth was the factor limiting fresh fish burger acceptability. 相似文献
105.
Alfonso Pompella Emilia Maellaro Alessandro F. Casini Marco Ferrali Lucia Ciccoli Mario Comporti 《Lipids》1987,22(3):206-211
A study was undertaken to investigate whether some of the methods commonly used to detect lipid peroxidation of cellular membranes
in vivo correlate with each other. The study was performed with the livers of bromobenzene-intoxicated mice, in which lipid
peroxidation develops when the depletion of glutathione (GSH) reaches a threshold value. The methods tested and compared were
the following: i) measurement of the malondialdehyde (MDA) content of the liver; ii) detection of diene conjugation absorption
in liver phospholipids; iii) measurement of the loss of polyunsaturated fatty acids in liver phospholipids; and iv) determination
of carbonyl functions formed in acyl residues of membrane phospholipids as a result of the peroxidative breakdown of phospholipid
fatty acids. Correlations among the values obtained with these methods showed high statistical significances, indicating that
the procedures measure lipid peroxidation in vivo with comparable reliability. Analogously, the four methods appeared also
to correlate when applied to in vitro microsomal lipid peroxidation. 相似文献
106.
Ricotti Yann Ducret Damien El Guerjouma Rachid Franciosi Patrick 《Mechanics of materials : an international journal》2006,38(12):1143-1158
Measured elasticity moduli of a highly (68%) glass-fiber reinforced epoxy matrix for different amounts of fiber/matrix interface weakening and debonding, due to different hygrothermal ageing stages, are compared to estimated ones. Ultrasonic measurements provide seven of the nine elasticity moduli of the orthotropic material samples, including all the moduli significantly affected by damage. Theoretical estimates combine homogenization modeling techniques and Finite Element (FE) calculations, the latter when the effect of observed partial debonding on effective moduli is to be specified. These estimates are performed under different assumptions for the composite structure, with special attention to the existence of a fiber–matrix interphase. Analytical comparisons for the undamaged composite establish that matching US measurements with estimates cannot be obtained, regardless of the chosen model, without the assumption of an interphase layer of modified resin coating the fibers. This coating resin, when in relevant concentration with regard to literature data about fiber coating thickness, typically conserves the epoxy moduli transversally to the fiber orientation, while, in the fiber direction its moduli approach those of the fibers. The comparison of the US measurements on damaged samples to FE calculations assuming progressive one-directional debonding shows that most of the composite stiffness loss can preferentially be due to an initial interphase weakening, while the fiber/matrix debonding seems more likely delayed to long H-ageing times. This is consistent with physical interpretation of damage by water pooling through silane bridges bonding epoxy to glass. The calculations also provide the effective stiffness, at different damage stages, of the “Undamaged Equivalent Inhomogeneity” for this damaged inclusion type. 相似文献
107.
Iñigo Navarro Antonio J. López-Martín Carlos A. de la Cruz Alfonso Carlosena 《Analog Integrated Circuits and Signal Processing》2004,41(2-3):159-166
A compact, four-quadrant analog CMOS multiplier featuring wide dynamic range is presented. The capacitive voltage division obtained by the use of Floating-Gate MOS (FGMOS) transistors, and an accurate wide-swing current mirror based on active bootstrapping, allow a wide input range, low harmonic distortion, and high linearity. Simulation and measurement results for a 0.8 μm CMOS prototype demonstrate the validity of the proposed approach. 相似文献
108.
The study of monthly mean half hourly values of global radiation received at 315 (u.v.) and 545 nm (green) on a horizontal surface at Uccle (Belgium) in 1980 for clear (half hourly sunshine fraction σ = 1) and overcast (σ = 0) skies shows that for any solar altitude, global radiation received at 315 nm is less absorbed by clouds than radiation received at 545 nm. An explanation is given of the dependence on solar altitude for clear skies of the ratio between monthly mean half hourly values of global radiation received at both wavelengths, based on considerations concerning the direct and diffuse components. 相似文献
109.
We address the problems of determining consistency and of finding a solution for sets of three-point relations expressing exclusion of a point from an interval, and for sets of four-point relations expressing interval disjointness. Availability of these relations is an important requirement for dealing with the sorts of temporal constraints encountered in many AI applications such as plan reasoning. We prove that consistency testing is NP-complete and finding a solution is NP-hard. 相似文献
110.
Amorphous poly(ethylene terephthalate) has been isothermally annealed in a wide range of temperatures from Tg to Tm. The effects of temperature and time of thermal treatment on density, melting curve and WAXS have been systematically explored. The results showed that densification and crystal perfection take place through a step mechanism involving partial melting and diffusion. The evaluation of the activation energies suggests that diffusion is the rate determining step in the low temperature range. 相似文献