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961.
Ulrich Pinkernella Stefan Effkemann Frank Nitzsche Uwe Karst 《Journal of chromatography. A》1996,730(1-2):203-208
The selective oxidation of methyl p-tolyl sulfide (MTS) to the corresponding sulfoxide (MTSO) by peroxyacetic acid and the subsequent rapid separation of the sulfide and sulfoxide are the basis for a fast and reliable HPLC method for the determination of this oxidizing agent in the presence of hydrogen peroxide. The time required for chromatographic separation was reduced to less than 1 min. To improve the long-term stability of the sulfoxide solution, hydrogen peroxide was decomposed catalytically by manganese dioxide. Even in the presence of a tenfold molar excess of hydrogen peroxide, a storability of at least 20 h without a significant increase in MTSO concentration was achieved. External calibration can be performed using the stable and commercially available MTSO. Real samples from a brewery cleaning-in-place disinfection process were analysed and the results were compared with those of the classical two-step titration. 相似文献
962.
963.
Stefan E. Schmidt 《Results in Mathematics》1993,23(3-4):384-386
This note presents a proof of Wedderburn’s theorem concerning the classification of semisimple rings within the conceptual frame of projective lattice geometry. 相似文献
964.
The vinylation of 9H-carbazole ( 1 ), 1H-indole ( 3a ), and 1H-pyrrolo[2,3-b]pyridine ( 3b ) with propiolic acid ethyl ester resulting in N-acrylic esters is reported here. 相似文献
965.
966.
Stefan Wojciechowski 《Reports on Mathematical Physics》1975,8(3):387-390
The relation between the geometry and the statistics of the quantum theory is most explicit in the convex models of quantum mechanics. A class of models is investigated where the manifold S of all states is a convex set with a smooth boundary. It is shown that for these models the simple assumption about symmetry of the transition probability implies an ellipsoidal shape of S, thus leading to the “spherical” geometries described in [7]. 相似文献
967.
If S is an arbitrary sequence of positive integers, let P(S) be the set of all integers which are representable as a sum of distinct terms of S. Call S complete if P(S) contains all large integers, and subcomplete if P(S) contains an infinite arithmetic progression. It is shown that any sequence can be perturbed in a rather moderate way into a sequence which is not subcomplete. On the other hand, it is shown that if S is any sequence satisfying a mild growth condition, then a surprisingly gentle perturbation suffices to make S complete in a strong sense. Various related questions are also considered. 相似文献
968.
969.
Stefan Marinov 《Foundations of Physics》1979,9(5-6):445-460
In the light of our recently performed experiments, revealing the anisotropy of light velocity in any frame moving with respect to absolute space, we show that the Lorentz transformation, where the relativity of light velocity is given implicitly through the relativity of the time coordinates, must be treated from an absolute point of view if one seeks to preserve its adequacy to physical reality. Then we propose a new transformation (which is to be considered as a legitimate companion of the Lorentz transformation) wherein the relativity of light velocity is given explicitly and the time coordinates are absolute. 相似文献
970.
Stefan Berger 《Magnetic resonance in chemistry : MRC》1980,14(1):65-68
A series of alicyclic compounds with dihedral angles of 0°, 60°, 90°, 120° and 180° between a 13C-labelled carbon atom and a carbon atom separated by three bonds from the label has been synthesized. The vicinal 13C13C spin coupling constants were measured, and from the results a Karplus-type relationship between 13C13C spin coupling and dihedral angle is proposed. 相似文献