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101.
102.
Milan Marhol 《Fresenius' Journal of Analytical Chemistry》1967,231(4):265-272
Summary Uranium or thorium separations from a number of various ions were studied by means of cation exchangers containing phosphorus in their functional group. These ion exchangers adsorb selectively only UO2
2+ or Th4+ ions from the mixture studied in a medium of >0.4 N nitric or hydrochloric acid. Several di- and trivalent cations are not sorbed under these conditions. In the absence of UO2
2+ and Th4+ ions, Me2+ may be more easily separated quantitatively from Me3+ in 0.2 N nitric or hydrochloric acid than with cation exchangers containing the -SO3H group.
Zusammenfassung Die quantitative Trennung von UO2 2+ oder Th4+ von einer Reihe anderer Ionen wurde mit Hilfe phosphorhaltiger Kationenaustauscher untersucht. Diese Ionenaustauscher sorbieren selektiv nur UO2 2+ oder Th4+-Ionen aus einem Medium von >0,4 N HNO3 oder HCl. Eine Reihe verschiedener zwei- und dreiwertiger Kationen wird unter diesen Bedingungen nicht sortiert. Bei Abwesenheit von UO2 2+- und Th4+-Ionen kann man Me2+ in 0,2 N HNO3- oder HCl-Lösung quantitativ von Me3+ trennen, und zwar leichter als mit -SO3H-haltigen Austauschern.相似文献
103.
A method has been developed for the quantitative coulometric permanganatometric micro-determination of hydrogen peroxide. The end-point is ascertained by the colour changes of the indicators ferroin, and nitro-ferroin respectively 相似文献
104.
An algorithm for encoding long strings of building blocks, like 4 DNA bases (adenine-A, cytosine-C, thymine-T, and guanidine-G), 20 natural amino acids (from Alanine Ala to Valine-Val, plus the stop triplet), or all 64 possible base triplets (from AAA to TTT), into "zigzag" or "spectrum-like" representations is suggested. The new encoding scheme can be derived in the 3-, 2-, or 1-dimensional form depending on the user's wishes. The only information, besides the string for which the "spectrum-like" representation is sought, is the initial positioning of the complete set of units from which the string is composed, i.e., four positions for A, C, G, and T, or 20 positions for natural amino acids plus stop, etc. This initial positioning can be initialized in either the 3-, 2-, or 1-D form. As an illustration of the suggested encoding scheme of the visual and chemometric comparison of the first 10 exon strings of the beta globin gene of 10 different species, each string consisting of about 100 basic amino acids long is shown. 相似文献
105.
Vorontsov II Kovalevsky AY Chen YS Graber T Gembicky M Novozhilova IV Omary MA Coppens P 《Physical review letters》2005,94(19):193003
Time-resolved single-crystal diffraction performed with synchrotron radiation shows that the 53(1) micros phosphorescent state, generated in the crystalline phase of trimeric {[3,5-(CF3)(2)Pyrazolate]Cu}(3) molecules by exposure to 355 nm of light at 17 K, is due to the formation of an excimer rather than the shortening of the intramolecular Cu...Cu distances within the trimeric units, or the formation of a continuous chain of interacting molecules. One of the intermolecular Cu...Cu distances contracts by 0.56 Angstroms from 4.018(1) to 3.46(1) Angstroms;, whereas the interplanar spacing of the trimers is reduced by 0.65 Angstroms; from 3.952(1) to 3.33(1) Angstroms. Density-functional theory calculations support the formation of a Cu...Cu bond through the intermetallic transfer of a Cu 3d electron to a molecular orbital with a large 4p contribution on the reacting Cu atoms. 相似文献
106.
Formation of the plasma potential in a plasma that contains energetic electrons and is bounded by a floating collector that
emits electrons is studied theoretically. The problem is treated by a static. kinetic plasma-sheath model of Schwager and
Birdsall [Phys. Fluids B2 (1990) 1057], which we have extended in order to include additional energetic electron population. The distribution of these
electrons is assumed to be a high-temperature Maxwellian. They are called hot electrons. In the paper we study effects of
the density and temperature of the hot electrons on the formation of the plasma potential. The model shows that for certain
densities and temperatures of the hot electron population plasmas with two different plasma potentials can coexist in the
system. These two plasmas are separated spatially by a double layer. For the case when there is no emission of electrons from
the collector, results of the model are compared with computer simulation and very good agreement between the model and the
simulation is found. The simulation also confirms existence of two plasmas with two different potentials separated by a double
layer. 相似文献
107.
108.
Randić M 《Journal of chemical information and computer sciences》2004,44(2):373-377
109.
Milan Práger 《Applications of Mathematics》2003,48(3):225-236
Fast direct solvers for the Poisson equation with homogeneous Dirichlet and Neumann boundary conditions on special triangles and tetrahedra are constructed. The domain given is extended by symmetrization or skew symmetrization onto a rectangle or a rectangular parallelepiped and a fast direct solver is used there. All extendable domains are found. Eigenproblems are also considered. 相似文献
110.
Milan Nádvorník Vratislav Langer Robert Jirásko Michal Holčapek Tomáš Weidlich Antonín Lyčka Alexander Popkov 《Polyhedron》2008
A preparative procedure for the synthesis of an important chiral synthon of side-chain protected tyrosine was developed and optimised for the minimisation of nickel salts waste. While preparing a similar side-chain protected tryptophan synthon, an unexpected low stability was found of the Boc-protective group of the tryptophan aromatic nitrogen during purification on silica gel. X-ray crystal structure determination, tandem mass spectrometry (MS/MS) and NMR were applied for the elucidation of the structures of the prepared complexes and by-products. Stereochemistry of products of α-methylation of the complexes was assessed using a model tyrosine-derived compound. 相似文献