997 resultados para 502.2


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Through the reaction of Co-2(CO)(8) with four thiuram [R2NC(S)S](2), four new sulfur-capped trinuclear cobalt carbonyl clusters Co-3 (CO)(7) (mu(3)-S) (mu, eta(2)-S* C* NR2) ( I : R = Me; I : R = Et; II : R = i-Pr; IV : NR= -N [GRAPHICS] were prepared and characterized by elementary analysis, IR,H-1 NMR and MS spectroscopy. The crystal structure of the cluster Co-3(CO)(7)(mu(3)-S)[mu, eta(2)-S*C*N (i-Pr)(2)]( III) was determined by X-ray single crystal diffraction method. The crystal of m is monoclinic, belonging to space group P2(1)/n, and the cell parameters are as follows: a = 1, 145 2(2) nm, b = 1. 502 8(3) nm, c = 1, 214 4(2) nmj alpha = 90 degrees, beta = 92, 15(3)degrees, gamma = 90 degrees; V = 2. 088 5(7) nm(3) , Z = 4, F (000) = 1 096, D-c = 1. 747 mg . m(-3), mu = 2. 588 mm(-1), R=0. 040 7, R-w=0. 062 4, The structural analysis shows that cluster II has a pyrimidal Co3S framework and contains a heterocylic bridging bidentate ligand [mu, eta(2)-S* C* N (i-Pr)(2)] linked to the Co2 and Co3 atoms of the cluster by a cobalt-carbon and a cobalt-sulfur bond respectively.

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Four typical LB monolayer film materials, Ru(phen)(3)(2+) complexes with one ligand attached to different long chain alkyl amides, were designed and synthesized. Their chemical structures were identified by the techniques of FT-IR, H-1 NMR and ESI-MS. Also, UV-Vis, electrochemistry and fluorescence of these complexes are reported.

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2,2'-Bis(3,4-dicarboxyphenoxy)-1,1'-binaphthyl dianhydride was used as a new monomer with various aromatic diamines to obtain polyimides by the usual two-step method. The bis(ether anhydride) was prepared by a nucleophilic substitution of I,1'-bi-2-naphthol with N-phenyl-4-chlorophthalimide, N-methyl-4-nitrophthalimide or 4-nitrophthalonitrile in aprotic polar solvent, and subsequent hydrolysis of the resulting bis(ether imide)s or bis(ether dinitrile), and then dehydration of the corresponding tetracarboxylic acid to afford the dianhydride. Most of the obtained polyimides were soluble in chloroform, pyridine, DMF, etc. The polyimide prepared from p-phenylene diamine was partial crystalline, whereas the others showed amorphous patterns in a WAXD study. These polymers have glass transition temperatures between 255-294 degrees C and 5% weight loss temperatures in the range of 502-541 degrees C in nitrogen and 473-537 degrees C in air. (C) 1997 Elsevier Science Ltd.

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Signaling of G protein-coupled receptors (GPCRs) is regulated by different mechanisms. One of these involves regulators of G protein signaling (RGS), which are diverse and multifunctional proteins that bind to active G alpha subunits of G proteins and act as GTPase-activating proteins. Little is known about the molecular mechanisms that govern the selective use of RGS proteins in living cells. We first demonstrated that CCK2R-mediated inositol phosphate production, known to be G(q-)dependent, is more sensitive to RGS2 than to RGS4 and is insensitive to RGS8. Both basal and agonist-stimulated activities of the CCK2R are regulated by RGS2. By combining biochemical functional, and in silico structural approaches, we demonstrate that a direct and functional interaction occurs between RGS2 and agonist-stimulated cholecystokinin receptor-2 (CCK2R) and identified the precise residues involved: phosphorylated Ser434 and Thr439 located in the C-terminal tail of CCK2R and Lys62, Lys63, and Gln67, located in the N-terminal domain of RGS2. These findings confirm previous reports that RGS proteins can interact with GPCRs to modulate their signaling and provide a molecular basis for RGS2 recognition by the CCK2R.

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Esta comunicación presenta algunos resultados preliminares de un trabajo de doctorado que tiene como objetivo Identificar cuáles son las potencialidades y limitaciones de los entornos virtuales colaborativos y las herramientas web 2.0 en la promoción del activismo sobre cuestiones ambientales en estudiantes de básica secundaria, se hace una descripción de la metodología que se enmarca dentro del paradigma de la complejidad y la evolución, la investigación acción y el análisis documental, es de carácter cualitativo y cuantitativo; al final se presenta un análisis preliminar de los resultados obtenidos con los blogs construidos por los estudiantes.

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Se trata de una noticia sobre las visitas recibidas por el portal de educación de la comunidad de Castilla-La Mancha y se concluye con la importancia de las nuevas tecnologías para el desarrollo de la comunidad .

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La Consejería de Educación y Ciencia de Castilla-La Mancha oferta actividades para mejorar las competencias comunitarias en otras lenguas y conseguir profesionales competentes en idiomas extranjeros capaces de insertarse en el mercado exterior.

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Docentes de Castilla-La Mancha participarán en el Plan de Formación Permanente del Profesorado de la región, donde se impartirán distintas actividades que contribuirán al desarrollo de la competencia profesional del profesorado.

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Los programas europeos son Gruntvig-2 y Arion

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Ca(2+) elevation is essential to platelet activation. STIM1 senses Ca(2+) in the endoplasmic reticulum and activates Orai channels allowing store-operated Ca(2+) entry (SOCE). STIM1 has also been reported to be present in the plasma membrane (PM) with its N-terminal region exposed to the outside medium but its role is not fully understood. We have examined the effects of the antibody GOK/STIM1, which recognises the N-terminal region of STIM1, on SOCE, agonist-stimulated Ca(2+) entry, surface exposure, in vitro thrombus formation and aggregation in human platelets. We also determined novel binding partners of STIM1 using proteomics. The dialysed GOK/STIM1 antibody failed to reduced thapsigargin- and agonist-mediated Ca(2+) entry in Fura2-labelled cells. Using flow cytometry we detect a portion of STIM1 to be surface-exposed. The dialysed GOK/STIM1 antibody reduced thrombus formation by whole blood on collagen-coated capillaries under flow and platelet aggregation induced by collagen. In immunoprecipitation experiments followed by proteomic analysis, STIM1 was found to extract a number of proteins including myosin, DOCK10, thrombospondin-1 and actin. These studies suggest that PM STIM1 may facilitate platelet activation by collagen through novel interactions at the plasma membrane while the essential Ca(2+)-sensing role of STIM1 is served by the protein in the ER.

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Polymers doped with rare earth complexes are advantaged in film production for many applications in the luminescent field. In this luminescent polycarbonate (PC) films doped with diaquatris(thenoyltrifluoroacetonate)europium(III) complex [Eu(TTA)(3)(H(2)O)(2)] were prepared and their calorimetric and luminescent properties in the solid state are reported. The thermal behavior was investigated by utilization of differential scanning calorimetry (DSC) and thermogravimetry (TG). Due of the addition of rare earth [Eu(TTA)(3)(H(2)O)(2)] into PC matrix, changes were observed in the thermal behavior concerning the glass transition and thermal stability. Characteristic broadened narrow bands arising from the (5)D(0) -> (7)F(J) transitions (J = 4-0) of Eu(3+) ion indicate the incorporation of the Eu(3+) ions in the polymer. The luminescent films show enhancement emission intensity with an increase of rare earth concentration in polymeric matrix accompanied by decrease in thermal stability.

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Water and saline intake is controlled by several mechanisms activated during dehydration. Some mechanisms, such as the production of angiotensin II and unloading of cardiovascular receptors, activate both behaviors, while others, such as the increase in blood osmolality or sodium concentration, activate water, but inhibit saline intake. Aldosterone probably activates only saline intake. Clonidine, anα2-adrenergic agonist, inhibits water and saline intake induced by these mechanisms. One model to describe the interactions between these multiple mechanisms is a wire-block diagram, where the brain circuit that controls each intake is represented by a summing point of its respective inhibiting and activating factors. The α2-adrenoceptors constitute an inhibitory factor common to both summing points.

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Briefwechsel zwischen Max Horkheimer und Theodor W. Adorno, 1927 - 1938; 1 Brief von Theodor W. Adorno an Hans F. Redlich, 1938; 1 Brief von Max Horkheimer an United States of America General Consul in Stuttgart, 1938; 1 Brief von Rudolph Kolisch an Theodor W. Adorno, 1938; 1 Brief von Paul F. Lazarsfeld an Theodor W. Adorno, 1938; 2 Briefe von Theodor W. Adorno an Paul F. Lazarsfeld, 1938; 1 Brief von Hanna Maaß an Gretel Adorno, 1937; Briefwechsel und Beilagen zwischen Max Horkheimer, Theodor W. Adorno und Gretel Adorno, 1939 - 1940; 1 Brief (Entwurf) von Theodor W. Adorno an Robert M. Hutchins, 1940; 4 Briefe von Friedrich Pollock an Theodor W. Adorno, 1940; 2 Briefe von Margot von Mendelssohn an Theodor W. Adorno, 1940; 2 Briefe von Theodor W. Adorno an Margot von Mendelssohn, 1940; 1 Brief von Franz L. Neumann an Theodor W. Adorno, 1940; 1 Brief (Entwurf von T.W. Adorno) von Max Horkheimer an Mrs. Charles E. Mitchell, 1940; 1 Brief und Beilage von Gretel Adorno an Frederick Wild, 1939; 1 Brief von French und Co. Eifert an Gretel Adorno, 1939; 2 Briefe von Theodor W. Adorno an Herbert W. Schneider, 1939; 1 Brief von Theodor W. Adorno an Jean Wahl, 1939; 1 Brief von Max Horkheimer an Roger M. Howson von der Columbia University Library in New York, 1939;