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1.
Stan J. Surma 《Logica Universalis》2007,1(1):209-219
The connection presented in this paper mirror-links two metamathematical structures, the finitary closure operators, and the
compact consistency properties, in such a way that a specification of one structure induces a provably equivalent specification
of the other.
Mathematics Subject Classification (2000): Primary 06A15, Secondary 28E10 03B22 相似文献
2.
Serguei Foss Takis Konstantopoulos Stan Zachary 《Journal of Theoretical Probability》2007,20(3):581-612
We consider a modulated process S which, conditional on a background process X, has independent increments. Assuming that S drifts to −∞ and that its increments (jumps) are heavy-tailed (in a sense made precise in the paper), we exhibit natural
conditions under which the asymptotics of the tail distribution of the overall maximum of S can be computed. We present results in discrete and in continuous time. In particular, in the absence of modulation, the
process S in continuous time reduces to a Lévy process with heavy-tailed Lévy measure. A central point of the paper is that we make
full use of the so-called “principle of a single big jump” in order to obtain both upper and lower bounds. Thus, the proofs
are entirely probabilistic. The paper is motivated by queueing and Lévy stochastic networks. 相似文献
3.
Zusammenfassung Durch spektrophotometrische Messungen in Dimethylformamid (DMF) werden die Koordinationsformen [CuCl]+ und [CuCl3]– sowie [NiCl]+, [NiCl3]– und [NiCl4]2– nachgewiesen. Bei Nickel(II)-chlorid und Kupfer(II)-chlorid wird Autokomplexbildung diskutiert. Die Solvate [Cu(DMF)4] (ClO4)2 und [Ni(DMF)6] (ClO4)2 werden isoliert.Im Zuge der Untersuchungen über Chlorokomplexe von Ionen der Übergangsmetalle1, 2 in nichtwäßrigen Lösungsmitteln wurden die Spektren der Lösungen von Kupfer(II)- und Nikkel(II)-perchlorat inDMF in Gegenwart verschiedener Mengen Tetraäthylammoniumchlorid aufgenommen.Mit 5 Abbildungen 相似文献
4.
Summary A high molecular weight sodium hyaluronate isolated from rooster combs was degraded by ultrasonication. High-performance size exclusion chromatography allowed rapid and accurate determination of molecular weight parameters (Mz, Mw, Mn) and distributions. The time dependence of hyaluronan ultrasonication to the molecular characteristics of the polymer was investigated. A non-random nature of the degradation process was demonstrated and the reciprocal Mn value was found to be linearly proportional to the time of ultrasonication. 相似文献
5.
J. Schormüller und H. -J. Stan 《Fresenius' Journal of Analytical Chemistry》1965,211(4):274-281
Zusammenfassung Es wird eine Methode beschrieben, die es gestattet, während einer automatischen Aminosäuretrennung an Ionenaustauschersäulen die Radioaktivität der einzelnen 14C-markierten Aminosäuren zu messen. Die aufgetrennten Fraktionen werden unmittelbar am Säulenausgang durch eine Meßanordnung geschickt, bestehend aus einem Scintillatorschlauch, der sich zwischen zwei in Koinzidenz geschalteten Photomultipliern befindet. Anschließend wird mit Ninhydrin angefärbt. Die Nachweisgrenze beträgt 2 · 10–3
C. Die Methode ist einfach zu handhaben, die Meßgeräte, einschließlich der Meßzelle, sind im Handel erhältlich.
Die Untersuchungen wurden durch den Minister für Atomkernenergie gefördert. Hierfür danken wir auch an dieser Stelle verbindlich.
Am Ausbau der Methode waren zeitweilig die Herren Dr. Ing. W. Heptner und Dr. Ing. S. Vierkötter beteiligt. 相似文献
Summary A method is described for the continuous measurement of 14C-labelled amino-acids during automatic separation by ion-exchanger columns. Immediately after emerging from the column the single fractions are passed through a measuring device consisting of a plastic scintillator between two photomultipliers in a coincidence circuit. Subsequently the eluate is reacted with ninhydrin. The limit of detection is 2 · 10–3 C. The procedure is simple and the measuring device is commercially available.
Die Untersuchungen wurden durch den Minister für Atomkernenergie gefördert. Hierfür danken wir auch an dieser Stelle verbindlich.
Am Ausbau der Methode waren zeitweilig die Herren Dr. Ing. W. Heptner und Dr. Ing. S. Vierkötter beteiligt. 相似文献
6.
Annals of Global Analysis and Geometry - We give an elementary and self-contained proof of the uniformization theorem for noncompact simply connected Riemann surfaces. 相似文献
7.
Photochemical and photophysical studies of a number of 9-substituted anthracene sandwich pairs in their corresponding photodimer crystal matrices have been carried out. Corresponding studies have also been made in methylcyclohexane matrices at 6 K. Photodimerization of the 9-methyl, 9-chloro and 9-cyano derivatives in the photodimer matrices occurs at 6 K with unit quantum yield. The presence of excimer fluorescence from sandwich pairs indicates the lack of a perfect topochemical orientation while activation processes, leading to photodimerization, involve molecular re-orientation from more stable ground state configurations which are achieved within the constraints imposed by the solvent or crystalline cage. 相似文献
8.
Regine Heyer Andreas Zapf H. -J. Stan 《Fresenius' Journal of Analytical Chemistry》1995,351(8):752-757
Two different extraction procedures to determine alachlor (2-chloro-2,6-diethyl-N-methoxymethyl-acetanilide) and its metabolites 2,6-diethylaniline (DEA) and 2-chloro-2,6-diethylacetanilide (CDEA) at very low concentration levels in groundwater are compared. Both methods were performed during a field leaching study and laboratory soil column experiments. Solid phase extraction (SPE) is characterized by the enrichment of 11 water samples at 1 g RP-C18 material, while micro liquid/liquid extraction (MLLE) means that 400 ml water samples saturated with sodium chloride were extracted once with 500 l of toluene. Both methods differ in their concentration factors, i.e. 5000 for SPE and 800 for MLLE. The determination limits for alachlor determined as the lowest spiked concentration analyzed are 10 ng/l with SPE and 25 ng/l with MLLE. Even though the determination limits of the two methods are similar, the volatile metabolite 2,6-diethylaniline was not sufficiently recovered by SPE. Furthermore, SPE is more expensive and time consuming than MLLE. The latter is simple in use, rapidly performed and needs no evaporation step and clean-up before GC analysis. This is of special advantage for the analysis of 2,6-diethylaniline. The determination limits of the metabolites CDEA and DEA analyzed by MLLE are 25 ng/l. The extracts from both methods were directly analyzed by gas chromatography using electron capture and nitrogen-phosphorus detection. 相似文献
9.
Daniela-Mdlina Ciuc Anghel Anne-Marie Ciobanu Claudia Maria Guu Miriana Stan Gheorghe Tudor Daniela Luiza Baconi 《Molecules (Basel, Switzerland)》2022,27(23)
(1) Background: Methadone, along with buprenorphine, is the most commonly used drug for the treatment of opioid dependence. This study aimed to analyze methadone and its major metabolite, 2-ethylidene-1,5-dimethyl-3,3-diphenyl pyrrolidine (EDDP), in the urine and plasma of opiate addicts. The study group consisted of drug users voluntarily admitted to the detoxification center C.E.T.T.T. “St. Stelian” of Bucharest. Secondly, the study aimed to identify whether urine or plasma provides better results for the proposed method. (2) Methods: A GC-MS method, using an internal standard (diphenylamine) in the FULL-SCAN and SIM modes of operation and using the m/z = 72 ion for methadone and the m/z = 277 ion for EDDP, combined with a liquid–liquid extraction procedure was performed. (3) Results: The applied procedure allows the detection and quantification of methadone in both urine and plasma samples. EDDP was identified in patients with higher levels of methadone. Higher levels of methadone were detected in urine than in plasma samples. (4) Conclusions: This procedure can be used in clinical laboratories for the rapid determination of methadone levels in urine rather than in plasma. The procedure can be applied for the monitoring of methadone substitution treatment. 相似文献
10.
Gregory B. Kharas Sonia E. Chavez Alex C. Mast Mark Krzeszowiec Stan Mazo 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(6):451-454
Novel copolymers of trisubstituted ethylene monomers, ring-substituted 1,1-dicyano-2-(1-naphthyl)ethylenes, RC10H6CH?C(CN)2 (where R is H, 2-OCH3, 4-OCH3) and 4-fluorostyrene were prepared by solution copolymerization in the presence of a radical initiator (ABCN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, 1H and 13C-NMR. The order of relative reactivity (1/r 1) for the monomers is (5.86) > 2-CH3O (4.28) > 4-CH3O (2.87). Relatively high Tg of the copolymers in comparison with that of poly(4-fluorostyrene) indicates a decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (7.3–7.7% wt.), which then decomposed in the 500–800°C range. 相似文献