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991.
Y. Jao W. L. Cheng H. J. Chen C. C. Shaeh C. C. Huang Y. M. Lin 《Journal of Radioanalytical and Nuclear Chemistry》1995,194(2):411-417
This study was performed under the joint TRMC/INER program for the determination of low level85Kr and133Xe concentrations in the environmental air samples. Based on cryogenic adsorption of krypton and xenon on charcoal followed by chromatographic separation from other gases, the85Kr and133Xe recovered from 200 liters of atmospheric air can be determined by either on-line gas flow proportional counter or liquid scintillation counting. The recovery yields of krypton and xenon examined by using85Kr and133Xe tracers were nearly 100%. The minimum detectable activity of85Kr and133Xe by gas flow proportional counting is about 7.40 Bq. The method is satisfactory for environmental monitoring applications under abnormal conditions of nuclear facilities. However, for lower level environmental85Kr and133Xe measurements, the liquid scintillation counting method can be applied due to their extremely low detection limits (i.e. 0.107 Bq and 0.093 Bq for85Kr and133Xe, respectively). Using this method, the measurable limits of concentrations are 0.535 Bq/m3 and 0.466 Bq/m3 for85Kr and133Xe, respectively. 相似文献
992.
H. L. Frisch Yongpeng Xue 《Journal of polymer science. Part A, Polymer chemistry》1995,33(12):1979-1985
A hybrid inorganic/organic interpenetrating polymer network (IPN) of a three-dimensional network structure zeolite crystal (13X, powder) and crosslinked or linear polystyrene (PS) was prepared and characterized by differential scanning calorimetry (DSC), solid-state13C-NMR, and scanning electron microscopy (SEM). The size and shape of the crystalline zeolite particles were revealed on SEM micrographs in both the pure zeolite and the IPNs. Solubility tests and the results of DSC with solid-state 13C-NMR confirm that some organic PS chains are incorporated within the internal three-dimensional channels of the zeolite particles. We speculate that the internal PS chains may adopt an extended “one-dimensional” conformation and exhibit no bulk polymer glass transition. These novel hybrid inorganic/organic IPNs are a new kind of IPN structure. © 1995 John Wiley & Sons, Inc. 相似文献
993.
We study the boundary value problem for the quasilinear equation u u ? uxx=F[u, ut], u(x, 0)= u(x, π)=0, u(x+w, t)=u(x, t), x ε ®, t ε [0, π], and establish conditions under which a theorem on the uniqueness of a smooth solution is true. 相似文献
994.
Summary Six commercial hydrogen standards containing helium, oxygen, nitrogen, methane and carbon dioxide at trace levels were analyzed
by gas chromatography, for periods up to 105 days. The concentrations, in the range of 0–120 μmol mol−1, were stable (with the exception of oxygen) but often significantly different from the certified values provided by the suppliers,
especially for helium, oxygen and nitrogen. Concurrently, some experiments were carried out to verify the stability of gas
mixtures based on hydrogen stored in cylinders submitted to different chemical and physical treatments. The causes that led
to the deviations observed, as well as the decreases in oxygen, are discussed.
Presented at the 21st ISC held in Stuttgart, Germany, 15th–20th September, 1996. 相似文献
995.
996.
M. Sugawara H. Kusakari T. Murakami T. Kohno 《The European Physical Journal A - Hadrons and Nuclei》1998,1(3):237-239
A new rotational band has been observed in 167Lu by 152Sm (19F,4n)reaction at the HI-13 tandem accelerator of CIAE in Beijing. The high spin transition energies of the new band are almost
identical to the triaxial superdeformed bands recently discovered in 163Lu and 165Lu. This new band is predicted as a triaxial superdeformed band by total routhian surface calculations.
Received: 6 October 1997 相似文献
997.
Rüdiger Schultz Leen Stougie Maarten H. van der Vlerk 《Mathematical Programming》1998,83(1-3):229-252
In this paper we present a framework for solving stochastic programs with complete integer recourse and discretely distributed right-hand side vector, using Gröbner basis methods from computational algebra to solve the numerous second-stage integer programs. Using structural properties of the expected integer recourse function, we prove that under mild conditions an optimal solution is contained in a finite set. Furthermore, we present a basic scheme to enumerate this set and suggest improvements to reduce the number of function evaluations needed. 相似文献
998.
James H. Schmerl 《Mathematical Logic Quarterly》1998,44(4):515-521
There is a recursive set of natural numbers which is the difference set of some recursively enumerable set but which is not the difference set of any recursive set. 相似文献
999.
In 1964 Davis and Adams established that the large increase of the thermal expansion and compressibility in the critical region
of the γ-to α-Ce phase transition occurs predominantly in the α phase. This provides strong evidence that a tricritical point
is realized in Ce. This also means that the aforementioned transition is not isomorphic and that α-Ce should have a distorted
fcc structure. A careful examination of Jayaraman’s data (1965) shows that a second-order transition line continues beyond
the tricritical point to the vicinity of a triple point on the melting curve. The phase boundary with the tricritical point
and the minimum of the melting curve are reconstructed within the framework of Landau theory.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 2, 111–117 (25 January 1998)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献