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731.
732.
Summary A combination of ion-exchange and micro-electrodeposition techniques permits the rapid separation of sub-microgram amounts of copper in a form suitable for determination with the electron probe microanalyser. Recoveries of 98% and standard deviations < 5% have been checked by other methods at the 10-g level.
Presented at the VI. International Symposium on Microtechniques September 1970, Graz, Austria. 相似文献
Zusammenfassung Eine Verbindung von Ionenaustausch und Elektrolyse ermöglicht die rasche Abscheidung von Submikrogrammengen Kupfer in einer für die Elektronenstrahlmikroanalyse geeigneten Form. Ausbeuten von 98% und Standardabweichungen von < 5% wurden mit anderen Verfahren im 10-g-Maßstab erwiesen.
Presented at the VI. International Symposium on Microtechniques September 1970, Graz, Austria. 相似文献
733.
McNae IW Fishburne K Habtemariam A Hunter TM Melchart M Wang F Walkinshaw MD Sadler PJ 《Chemical communications (Cambridge, England)》2004,(16):1786-1787
The 1.6 [Angstrom] X-ray crystal structure of [(eta(6)-p-cymene)Ru(lysozyme)Cl(2)], the first of a half-sandwich complex of a protein, shows selective ruthenation of Nepsilon of the imidazole ring of His15. 相似文献
734.
Hanekom D McKenzie JM Derix NM Koch KR 《Chemical communications (Cambridge, England)》2005,(6):767-769
In acetonitrile solutions at room temperature, cis-[M(L-S,O)2] Pt(II) and Pd(II) complexes of N,N-diethyl-N'-3,4,5-trimethoxybenzoylthiourea undergo reversible photoinduced isomerisation to the corresponding trans isomer upon irradiation with visible light in the 320-570 nm range, the rate and extent of isomerisation being significantly higher for the cis-[Pd(L-S,O)2] complex compared to the Pt(II) analogue; in the dark trans-[M(L-S,O)2] cleanly reverts back to the cis complex at a rate dependent on the solution temperature, indicating a thermally controlled reverse process. 相似文献
735.
Routine,high-sensitivity,cold vapor atomic absorption spectrometric determination of total mercury in foods after low-temperature digestion 总被引:1,自引:0,他引:1
A cold vapor atomic absorption spectrometric method was developed for the subnanogram-per-gram determination of total Hg in a wide variety of foods. Foods were weighed into 50 mL polypropylene centrifuge tubes and dried without charring at 55 degrees C in a circulating oven. Samples were then digested at 58 degrees C with HNO3, HCl, and H2O2. After matrix modification with solutions of 2% Mg(NO3)2, 0.01% Triton X-100, and Cu(II) at 10 microg/mL, samples were analyzed by using a CeTAC Technologies M-6000A dedicated Hg analyzer. Based on a 2 g sample weight, the detection limit of the method over 12 batches averaged 0.30 ng/g wet weight and ranged from 0.03 to 0.6 ng/g. Recoveries of Hg added to 17 different foods, analyzed in a routine manner, averaged 97%, and individual recoveries ranged from 77 to 107%. Accuracy was confirmed by analysis of 7 biological reference materials from the National Research Council of Canada and the National Institute of Standards and Technology. Stabilization of low concentrations of Hg in solutions containing no sample was required to prevent loss of Hg from blanks. In a comparison of NaCl, potassium dichromate, and Au(II), chloride was much more effective for stabilization than the other two, and HCl was used for subsequent stabilization. 相似文献
736.
Batchelor R Hagen D Johnson I Beechem J 《Combinatorial chemistry & high throughput screening》2003,6(4):287-291
The fluorescent PicoGreen reagent for detection and quantitation of double-stranded DNA has been adapted for high-throughput screening: the RediPlate PicoGreen double-stranded DNA assay format. In the RediPlate PicoGreen assay format, the PicoGreen reagent is predistributed and co-dried into either 96- or 384-well microplates with the excipient trehalose. The user resuspends the dried reagents upon adding DNA, and measures the resulting fluorescence after a five minute incubation. Replicate fluorescence measurements on nominally identical wells have less than a 5% coefficient of variation. The assay is linear from 5 to 500 ng/ml DNA in a 200 micro l volume. The RediPlate PicoGreen assay format retains the advantages of the original PicoGreen reagent - sensitivity, speed, and specificity - but in a high-throughput format. 相似文献
737.
Ralph McKenzie 《Algebra Universalis》1983,16(1):195-203
Define \( n_K (\lambda )\) tobe eitherω, or the number of non-isomorphic algebras in \(K\) ] having cardinality λ, whichever cardinal is larger. It is proved here that if \(K\) ] is a quasi-variety (universal Horn class) of semigroups, then \(n_K\) is one of four functions. Each of these functions satisfies: \(n_K (\omega ) = \omega\) or \(n_K (\omega ) = 2^\omega\) . If \(n_K (\lambda )< 2^\lambda\) for some infinite λ then \(K\) ] is a residually finitevariety. 相似文献
738.
739.
M. Zieliński A. Zielińska H. Papiernik-Zielińska G. Czarnota G. Kasprzyk J. A. McKenzie H. Paul S. Bernasconi 《Journal of Radioanalytical and Nuclear Chemistry》1997,223(1-2):41-45
The13C fractionation has been studied in the reaction of phenylacetylene with the excess of liquid Merck formic acid at 30 and 40 °C to see the contribution of the13C fractionation in the formolysis of transient -formoxystyrene to the experimentally observed global13C fractionation. The13C fractionation has been investigated also in the hydration of 1 ml of PhCCH with 1 ml of formic acid in the temperature interval of 80–100°C. The13C KIE equal to 1.0168 at 91.75 °C and 1.0167 at 100°C indicate that the self-decomposition of formic acid in such experimental conditions is already largely suppressed. The isotope effect is discussed within the framework of the sequence of reaction steps leading to acetophenone and carbon monoxide production listed in part I. 相似文献
740.
The synthesis of two ethylene-bridged bidentate phosphines is described. 1,2-Bis(1-phospholano)ethane ((C(4)H(8))PCH(2)CH(2)P(C(4)H(8))) was synthesized by the stepwise addition of 2,2-dioxo-1,3,2-dioxathiepane to H(2)PCH(2)CH(2)PH(2). 1,2-Bis(1-phosphorinano)ethane ((C(5)H(10))PCH(2)CH(2)P(C(5)H(10))) was synthesized by the novel photochemical addition of 1,4-pentadiene to H(2)PCH(2)CH(2)PH(2). These bis(phosphines) form two-to-one complexes of the form Fe(PP)(2)Cl(2) when added to iron(II) chloride. 相似文献