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Tracer methods, such as radioisotope dilution, radiometric analysis, concentration dependent distribution, saturation analysis etc., are compared on a basis of radioactivity-mass balance relationships, and their automation is proposed. The requirements of a chemical separation, which is an integral part of these methods, are discussed. It is shown that automation, in addition to its obvious advantages, enables entirely new procedures to be developed, based on chemical separations which do not give reproducible results when performed normally. Simple commercially available apparatus has been used to verify these concepts by determination of traces of mercury. As little as 0.005 ppm of Hg can be determined, the detection limit being about a tenth of this. In the range 2.4-0.03 ppm, 20 samples/hr can be analysed, for lower amounts the sampling rate is 10 samples/hr. 相似文献
64.
X-Ray Structure Analysis of N-((E)-2-Methyl-2-butenyl)-N-(4-methylphenylsulfonyl)-N′-(4-nitrophenyl)sulfurdiamide The title compound crystallizes in the monoclinic space group P21/n with a = 16.893(3), b = 14.285(2), c = 18.422(4), β = 114.765(5)°, V = 4037 Å3, Z = 8. The formal S? N single bonds of the diaminosulfane moiety are shortened and differ in length (1.700 and 1.644 Å). The bonds of the N? S? N group to the p-nitrophenyl and tosyl rest are also a bit shorter than single bonds. The hybridization of the N atoms of the N? S? N moiety is sp2 with a tendency in the direction of sp3. Analogously to open chained sulfur diimides with respect to the N? S? N moiety an E/Z configuration can be derived. In the crystal structure the molecules are connected to one-dimensional polymers via hydrogen bridges between the nitrogen of the secondary amino group as a donor and an oxygen of the nitro group as an acceptor. 相似文献
65.
Schumm BA Merritt FS Oreglia MJ Schellman H Bachmann KT Bernstein RH Blair RE Foudas C Lefmann WC Leung WC Mishra SR Oltman E Quintas PZ Sciulli FJ Shaevitz MH Smith WH Borcherding FO Fisk HE Lamm MJ Marsh W Merritt KW Yovanovitch D Bodek A Budd HS Sakumoto WK 《Physical review letters》1988,60(16):1618-1621
66.
The true muonium \({(\mu\bar{\mu})}\) bound state presents an interesting test of light-cone quantization techniques. In addition to exhibiting the standard problems of handling non-perturbative calculations, true muonium requires correct treatment of \({e\bar{e}}\) Fock-state contributions. Having previously produced a crude model of true muonium using the method of iterated resolvents, our current work has focused on the inclusion of the box diagrams to improve the cutoff-dependent issues of the model. Further, a parallel computer code, TMSWIFT, allowing for smaller numerical uncertainties, has been developed. This work focuses on the current state of these efforts to develop a model of true muonium that is testable at near-term experiments. 相似文献
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Ohne Zusammenfassung
Für den ersten Teil der Arbeit genossen wir die Unterstützung der Forschungsgemeinschaft der Deutschen Wissenschaft, für den
zweiten Teil die der George Fisher Baker Foundation. Beiden, wie auch Herrn Prof. L. M. Dennis sei unser Dank abgestattet. 相似文献
69.
Tobias Lamm 《偏微分方程通讯》2013,38(2):245-262
In this paper a one-dimensional Keller–Segel model with a logarithmic chemotactic-sensitivity and a non-diffusing chemical is classified with respect to its long time behavior. The strength of production of the non-diffusive chemical has a strong influence on the qualitative behavior of the system concerning existence of global solutions or Dirac-mass formation. Further, the initial data play a crucial role. 相似文献
70.
Thermal 1,3-dipolar cycloaddition reactions of 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene dihydridoboron azide occur smoothly with alkynes, nitriles, and alkenes bearing electron-withdrawing groups. New, stable NHC-boryl-substituted triazoles, tetrazoles, and triazolidines are formed in good to excellent yields. 相似文献