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991.
Pyrazolo[1,5-d][1,2,4]triazines were synthesized from pyrazolecarboxylic acid hydrazides and carbonyl compounds. Pyrazolecarboxylic acid N-phenylhydrazide (1c) and formaldehyde gave not only the expected 4hn but 5 , respectively. The methyl substituted hydrazides with acetone afforded hydrazones, pyrazolotriazines or 13 depending on the position of the substituents. The reduction of both products yielded pyrazolecarboxylic acid hydrazides. 相似文献
992.
993.
Zusammenfassung Spuren von Zn, Cu, Ni, Co, Fe, Mn und Mo in Rheniummetall werden aus einer Einwaage ermittelt. Mo wird photometrisch als ternäres Mo(VI)Hydroxylamin-PAR-Chelat bestimmt. Die übrigen Elemente werden als PAN-Chelate gefällt und im abgetrennten Niederschlag mittels Röntgenfluoreszenzanalyse bestimmt.
A contribution to the determination of trace contaminants in rhenium metal
Summary Traces of Zn, Cu, Ni, Co, Fe, Mn, and Mo in rhenium metal were determined in a single weighed sample. Molydenum was determined photometrically as ternary Mo(VI)-hydroxylamine-PAR-chelate. The other elements were precipitated as PAN-chelates and then determined in the isolated precipitate by means of roentgen fluorescence analysis.相似文献
994.
Beside the transition into a ferroelectric phase at 583 K, monoclinic SrTeO3(I) at ?1260 K transforms slowly into a high-temperature form (SrTeO3(II)) which after quenching undergoes rapid phase transitions at 648 and 733 K. X-Ray data of triclinic α-SrTeO3(II) (room temperature), monoclinic β-SrTeO3(II) (660 K), and monoclinic γ-SrTeO3(II) (770 K) are presented. 相似文献
995.
Summary For the examples shown in this study in all cases FD-MS allowed the determination of the molecular weight and the elemental composition. Some of the characteristic features of sulphonic acids and sulphonates in field desorption are described. The method is obviously very well suited for the analysis of non-volatile technical products (e.g. dyestuffs, detergents, drugs). Information about the molecular weight, the structure, organic and inorganic by-products and impurities is obtained and thus the applicability of FD-MS to the analysis of actual analytical problems is clearly demonstrated.
Hochauflösungs-Felddesorptions-MassenspektrometrieIII. Sulfonsäuren und Sulfonate
Zusammenfassung Für die untersuchten Verbindungen ergab FD-MS in allen Fällen das Molekulargewicht und die Bruttoformel. Einige der charakteristischen Merkmale von Sulfonsäuren und Sulfonaten bei der Felddesorption werden beschrieben. Die Methode ist für die Analyse nichtflüchtiger, technischer Produkte (z. B. Farbstoffe, Detergentien, Pharmazeutica) sehr gut geeignet. Sie liefert Informationen über das Molekulargewicht, die Struktur, organische und anorganische Nebenprodukte und Verunreinigungen.
Part II.: Schulten, H.-R., Games, D. E.: Glycosides. Biomed. Mass Spectrom. 1, 120 (1974). 相似文献
996.
The Electron impact mass spectra of (CO)3 MC6H5—X complexes (M = Cr, W; X = OCH3, OC4H9, CO2CH3, CO2C4H9) were recorded. From metastable transitions and by high-resolution measurements complete fragmentation diagrams were obtained; in some cases comparative structure determinations of fragment ions were carried out by collisional activation. The fragmentation of the tungsten complexes considerably differs from that of the chromium compounds. The differences may be attributed to the stronger-electrophilic character as well as to the more pronounced tendency of tungsten to attain higher oxidation states. 相似文献
997.
Zusammenfassung Eine Apparatur zur Bestimmung kleiner Dichtedifferenzen wird beschrieben, die einen mit einem kleinen Magneten versehenen
Schwimmer enth?lt, der durch ein in me?barer Weise ver?nderliches magnetisches Feld in der Flüssigkeit zum Schweben gebracht
wird. Zur Messung werden nur 10 ml L?sungsmittel und 10 ml L?sung ben?tigt. Die Empfindlichkeit betr?gt etwa 2 · 10−6 g/cm3 (2 Stellen der sechsten Dezimale der Dichte).
Die zum Vergleich bestimmten partiellen spezifischen Volumen von Rinder-Serumalbumin und Chymotrypsinogen ergaben für das
erstere im Konzentrationsbereich zwischen 0,04 und 0,65% einen Mittelwert von 0,7335 (20,0° C) und für das letztere einen Wert von 0,720 (21,6° C). 相似文献
998.
K. Rühlmann J. Brumme U. Scheim H. Grosse-Ruyken 《Journal of organometallic chemistry》1985,291(2):165-178
The kinetics of hydrolysis reactions of some chlorodisiloxanes and of the chloropentasiloxanes (Me3) SiO)2Si(Me)OSiAr(Cl)OSiMeAr′ (with Ar = Ph and Ar′ = p-ClC6H4, C6H5 or p-MeC6H4; or Ar′ = Ph and Ar = p-ClC6H4, C6H5 or p-MeC6H4 in dioxane were studied by 1H NMR spectroscopy.Because of their high hydrolysis rate the chlorodisiloxanes can be reacted only with equimolar amounts of H2O. The formal second order rate constants and also the ? value evaluated can be used only in a tentative way.From hydrolysis reactions of the chloropentasiloxanes with an excess of H2O and different amounts of HCl or HClO4 the following results were obtained: hydrolysis is catalysed by HCl and HClO4. The reaction is of first order with respect to chlorosiloxane. With respect to HCl at a tenfold excess of H2O the order is in the range 0.5–0.7. Our results indicate, that there is a “non-catalysed” hydrolysis besides the acid catalysed reaction, ?-Values for the variation of Ar (0.7) and Ar′ (0.3) can be derived from the rate constants of the acid catalysed reactions of chloropentasiloxanes with a tenfold amount of water. The results are interpreted in mechanistic terms. 相似文献
999.
1000.
Jürgen G. Hinz 《Monatshefte für Mathematik》1983,95(4):275-286
Let ν denote a totally positive integer of an algebraic number fieldK such that ν is a least primitive root modulo a prime ideal \(\mathfrak{p}\) ofK, least in the sense that its normNν is minimal. One of the simplest questions that presents itself is that of the order of magnitude ofNν in comparison toN \(\mathfrak{p}\) . In the present paper the following bound is shown: $$N_\nu<< N\mathfrak{p}^{{1 \mathord{\left/ {\vphantom {1 4}} \right. \kern-\nulldelimiterspace} 4} + a} for fixed a > 0.$$ The proof of this result is based on deep estimates for certain character sums inK. 相似文献