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排序方式: 共有185条查询结果,搜索用时 93 毫秒
1.
Synthesis,Electronic Properties and WOLED Devices of Planar Phosphorus‐Containing Polycyclic Aromatic Hydrocarbons 下载免费PDF全文
Dr. François Riobé Rózsa Szűcs Dr. Pierre‐Antoine Bouit Dr. Denis Tondelier Bernard Geffroy Fátima Aparicio Julia Buendía Prof. Luis Sánchez Prof. Régis Réau Prof. László Nyulászi Prof. Muriel Hissler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(17):6547-6556
We describe the synthesis and the physical properties of polyaromatic hydrocarbons (PAHs) containing a phosphorus atom at the edge. In particular, the impact of the successive addition of aromatic rings on the electronic properties was investigated by experimental (UV/Vis absorption, fluorescence, cyclic voltammetry) and theoretical studies (DFT). The physical properties recorded in solution and in the solid state showed that the P‐containing PAHs exhibit properties expected for an emitter in white organic light‐emitting diodes (WOLEDs). 相似文献
2.
Composite membranes were prepared by (a) infiltrating NAFION with SiO2-P2O5-ZrO2 sol, and (b) recasting a film using NAFION solution containing SiO2-P2O5-ZrO2 sol. The membranes were characterized by Differential Thermal Analysis and ac-impedance spectroscopy as a function of relative humidity. The influences of the heat treatment (80°C–150°C) and cleaning on the electrical properties were investigated. The incorporation of SiO2-P2O5-ZrO2 gels into NAFION lead to improvements in its thermal stability and proton conductivity. 相似文献
3.
Santoyo E Verma SP Sandoval F Aparicio A García R 《Journal of chromatography. A》2002,949(1-2):281-289
A suppressed ion chromatography (IC) technique has been evaluated as a chemical monitoring tool for detecting major anions (F-, Cl-, NO3- and SO4(2-)) of condensed steam in geothermal power plants. It is shown that the suppressed IC technique provides a suitable means for preventing possible damage to generating equipment in the geothermal industry. An electrical conductivity detector (0.1 microS sensitivity) with an anion-exchange column (IonPac AS4A-SC), a micro-membrane suppressor (AMMS II), and an isocratic high-pressure pump system were successfully used for detecting low concentrations of inorganic anions. Method detection limits for the anions of interest were <0.184 mg/L. Details of the IC methodology as well as some experimental results obtained during its application for the chemical monitoring of geothermal steam pipes are also described. 相似文献
4.
AISI 304 Stainless Steel is widely used in different industrial fields because of its mechanical and corrosion properties.
However, its tendency to corrosion in presence of halide ions limits the applications. One strategy to improve the corrosion
resistance is the use of coatings barriers containing corrosion inhibitors in their formulation. The lanthanides present attractive
green and corrosion properties for the substitution of chromates, which are the most common substances used as corrosion protection.
However, these compounds are highly toxic, and an intense effort is being undertaken to replace them. Cerium is a good alternative
because of its relatively low cost and abundance. It fulfils the basics requirements for being considered an alternative inhibitor:
the ions form insoluble hydroxides and they present low toxicity. Inorganic and hybrid sol-gel coatings have been developed
to increase the corrosion resistance of metals and they provide an excellent vehicle for the incorporation of secondary phases
including particles and metal ions as cerium ions.
The aim of this work was to study the influence of the incorporation of cerium ions in hybrid silica sol-gel coatings deposited
on AISI 304 stainless steel as substrate as a potential replacement of chromate treatments. This system should combine the
barrier protection effect of silica coating with the corrosion inhibitor effect of the cerium ions inside the coatings. After
7 days of immersion in NaCl, coated substrates showed lower current densities than the bare steel, although the coatings produced
from Ce (III) salts experience a slight weakening in time and those obtained from Ce (IV) chemicals evidence an enhance in
the coating performance, probably due to the plugging of corrosion products in the defective areas of the film. 相似文献
5.
The uptake and assimilation of HCO3 by the green unicellular alga Monoraphidium braunii can be monitored by the alkalinization of the external medium or by the O2 evolution associated with the uptake and reduction of this anion. The activation of HCO3 uptake in this microalga required the irradiation of the cell suspensions with low photon fluence rates of short wavelength radiation. Thus, when the cells were irradiated with strong red light in the presence of HCO3, very little alkalinization of the external medium or O2 evolution could be observed. The O2 evolution rates measured under red light could be due to the assimilation of the CO2 derived from the HCO3 present in the medium. The blue light-dependent O2 evolution rates were not diminished by a periplasmic carbonic anhydrase inhibitor, suggesting that HCO3 -dependent O2 evolution was due to the photoactivation of a selective HCO3 uptake system at the plasma membrane. The action spectrum for HCO3- uptake in M. braunii was very similar to those reported for NO3- and CI- suggested that a flavoprotein may be the photoreceptor for this response. 相似文献
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The adequation of the current theories for calculating activity coefficients has been studied for a series of ionic equilibria in analytical chemistry: the water ionic product as well as two reactions of complex formation and oxidation-reduction. In all the cases, the specific interaction theory (SIT) has proved to be adequate and simple to apply in a restricted interval (0.5-3M), whereas Pitzer's theory is outstanding for its high precision in reproducing experimental behaviour and to correlate values of equilibrium constants for different conditions and media. 相似文献
9.
Palacios F Aparicio D Ochoa De Retana AM de los Santos JM Gil JI Alonso JM 《The Journal of organic chemistry》2002,67(21):7283-7288
A simple and efficient asymmetric synthesis of 2H-azirine-2-phosphine oxides 3 is described. The key step is a solid-phase bound achiral or chiral amine-mediated Neber reaction of beta-ketoxime tosylates derived from phosphine oxides 1. Reaction of 2H-azirines 3 and 11 with carboxylic acids 4 gives phosphorylated ketamides 5 and 12. Ring closure of ketamides 5 and 12 with triphenylphosphine and hexachloroethane in the presence of triethylamine leads to the formation of phosphorylated oxazoles 8 and 13. 相似文献
10.
Wijkens P Jastrzebski JT van Der Schaaf PA Kolly R Hafner A van Koten G 《Organic letters》2000,2(11):1621-1624
A general method for the functionalization of Si-Cl terminated carbosilane dendritic molecules via organolithium or organomagnesium reagents is described. Quantitative exchange of the bromine atoms of 4-bromophenyl-functionalized dendrimers affords polylithiated species that are valuable starting materials for further functionalization, e.g., into pyridyl alcohols. The latter were successfully applied as catalyst precursors in a ruthenium-mediated ring-closure metathesis reaction. 相似文献