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21.
22.
The addition of possible oxidation and/or isomerization products (butadiene, water, isomeric n-butenes) resulted in neither promotion nor inhibition in the oxidative dehydrogenation of n-butenes over tin-antimony mixed oxide catalysts. On the basis of these and other information on the influence of products an interpretation has been given to complete the reaction mechanism more realistic than those based on previous experimental results.
(, ) ( -) , . , , .相似文献
23.
Szabolcs Osváth Nóra Vajda Zsuzsa Molnár Éva Kovács-Széles Mihály Braun Máté Halász 《Journal of Radioanalytical and Nuclear Chemistry》2017,314(1):31-38
A radioanalytical method (based on separation using UTEVA columns and ICP-MS measurement) has been used for determination of 93Zr in 37 nuclear power plant samples. As 93Nb might affect the detection of 93Zr, Monte Carlo activation model was used to calculate the expected 93Zr/natZr mass ratio, which was compared to measured ones. It was found, that a decontamination factor of 103 is sufficient to get a measurement uncertainty of less than 10%. 相似文献
24.
Todd Cochrane 《Journal of Number Theory》2006,116(2):270-292
For any additive character ψ and multiplicative character χ on a finite field Fq, and rational functions f,g in Fq(x), we show that the elementary Stepanov-Schmidt method can be used to obtain the corresponding Weil bound for the sum ∑x∈Fq?Sχ(g(x))ψ(f(x)) where S is the set of the poles of f and g. We also determine precisely the number of characteristic values ωi of modulus q1/2 and the number of modulus 1. 相似文献
25.
We obtain upper bounds for mixed exponential sums of the type
where pm is a prime power with m⩾ 2 and X is a multiplicative character (mod pm). If X is primitive or p⫮(a, b) then we obtain |S(χ,f,p
m)| ⩽2np
2/3 m. If X is of conductor p and p⫮( a, b) then we get the stronger bound |S(χ,f,p
m)|⩽np
m/2.
This paper is dedicated to Prof. Wang Yuan on the occasion of his 70th birthday. 相似文献
26.
For any integersa
1,a
2,a
3,a
4 andc witha
1
a
2
a
3
a
4≢0(modp), this paper shows that there exists a solutionX=(x
1,x
2,x
3,x
4) ∈Z
4 of the congruencea
1
x
1
2
+a
2
x
2
2
+a
3
x
3
2
+a
4
x
4
2
≡c(modp) such that
Research of Zheng Zhiyong is supported by NNSF Grant of China. He would also like to thank the first author and the Mathematics
Department of Kansas, State University for their hospitality and support. 相似文献
27.
G.R. Clark C.M. Cochrane W.R. Roper L.J. Wright 《Journal of organometallic chemistry》1980,199(2):C35-C38
The osmium carbyne complex, Os(CR)Cl(CO)(PPh3)2, (R p-tolyl) reacts with Group I halides to form the mixed dimetallocyclopropene species, R)Cl(CO)(PPh3)2, R)Cl(CO)(PPh3)2, R)Cl(CO)(PPh3)2, and [R)Cl(CO)(MeCN)(PPh3)2] ClO4 X-ray crystal structure determination of R)Cl(CO)(PPh3)2 confirms the presence of a three-membered ring and the structure can be viewed as the “acetylene-like” interaction of an osmium—carbon triple bond with AgCl. In acid solution AgCl is precipitated and an alkylidene complex results from proton addition to the carbyne ligand. 相似文献
28.
Todd Cochrane Christopher Pinner 《Proceedings of the American Mathematical Society》2005,133(2):313-320
For a sparse polynomial , with and , we show that
thus improving upon a bound of Mordell. Analogous results are obtained for Laurent polynomials and for mixed exponential sums.
thus improving upon a bound of Mordell. Analogous results are obtained for Laurent polynomials and for mixed exponential sums.
29.
Hal Caswell 《Linear algebra and its applications》2013,438(4):1727-1745
Markov chains are often used as mathematical models of natural phenomena, with transition probabilities defined in terms of parameters that are of interest in the scientific question at hand. Sensitivity analysis is an important way to quantify the effects of changes in these parameters on the behavior of the chain. Many properties of Markov chains can be written as simple matrix expressions, and hence matrix calculus is a powerful approach to sensitivity analysis. Using matrix calculus, we derive the sensitivity and elasticity of a variety of properties of absorbing and ergodic finite-state chains. For absorbing chains, we present the sensitivities of the moments of the number of visits to each transient state, the moments of the time to absorption, the mean number of states visited before absorption, the quasistationary distribution, and the probabilities of absorption in each of several absorbing states. For ergodic chains, we present the sensitivity of the stationary distribution, the mean first passage time matrix, the fundamental matrix, and the Kemeny constant. We include two examples of application of the results to demographic and ecological problems. 相似文献
30.