نتایج جستجو برای: alkali metal
تعداد نتایج: 210259 فیلتر نتایج به سال:
The value assignment of candidate Standard Reference Material (SRM) 57b Silicon Metal provided an opportunity to develop an alkali reaction procedure as a precursor to borate fusion for the preparation of test specimens from the metal powder for X-ray fluorescence spectrometry (XRF). Suggested for this purpose by Blanchette (Adv. X-Ray Anal., 45, 415, 2002), the alkali reaction uses LiOH·H2O to...
The efficient citral hydrogenation was achieved in aqueous media using Pd/CMS and alkali additives like K2CO3. The alkali concentrations, reaction temperature and the Pd metal content were optimized to enhance the citral hydrogenation under aqueous media. In the absence of alkali, citral hydrogenation was low and addition of alkali promoted to ~92% hydrogenation without reduction in the selecti...
Macrocyclic planar tris-dipyrrin BF(2) complexes exhibit strong alkali-metal recognition and pseudorotaxane formation ability with a secondary ammonium salt through BF(2)-cation interactions.
Flavins are a fundamental class of biomolecules, whose photochemical properties strongly depend on their environment and their redox and metalation state. Infrared multiphoton dissociation (IRMPD) spectra of mass selected isolated metal-lumiflavin ionic complexes (M+LF) are analyzed in the fingerprint range (800-1830 cm-1) to determine the bonding of lumiflavin with alkali (M=Li, Na, K, Cs) and...
The peptidocalixarenes 1–3 bearing tryptophan, phenylglycine and leucil units at the lower rim and their complexes with alkali-metal (Li, Na, K, Rb, Cs) and selected lanthanide cations (La, Ce, Eu, Yb) were analyzed by ESI MS. The influences of the solvent (acetonitrile, methanol, addition of formic acid or sodium acetate) and the calixarene:cation molar ratio on signal intensities were investi...
In contrast to the growing interest with the polysilane, the method of preparation hitherto known is highly limited. So far, the almost only practical method is the condensation of organodichlorosilane with alkali metal (Wurtz type condensation). This method, however, requires drastic reaction conditions and hence, is very much limited in the type of substituent that is allowed to be located on...
The syntheses and characterization of alkali metal complexes [{VO2L}M(H2O}n] (1 & 2) [M = Na (1), K (2)] of anionic cis-dioxovanadium(V) species (LVO2 ) of the Schiff base 2-hydroxybenzoylhydrazone of 2-hydroxybenzaldehyde have been reported. The number of coordinated water molecules in [{VO2L}M(H2O}n] decreases as the charge density of the alkali metal ion decreases (n = 5 for Na and 1 for K)....
Transition metals are essential components of important biomolecules, and their homeostasis is central to many life processes. Transmembrane transporters are key elements controlling the distribution of metals in various compartments. However, due to their chemical properties, transition elements require transporters with different structural-functional characteristics from those of alkali and ...
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