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Time-resolved measurements of the thermal lens effect have been made for CH3F, CH3CI and C2H4. This technique is compared to others used in the study of vibrational relaxation phenomena and is found to be applicable to the study of a wide variety of gaseous systems at relatively low pressures. Translational cooling has been observed in CH3F and an approximate lower limit of 200 msec-1 has been established for the rate of this cooling process, which corresponds to equilibration of the ν3 and ν6 states, in a mixture of 0.2 torr CH3F and 10 torr Ar. 相似文献
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考察十七、十八世纪的数学状况,叙述早期微积分的技巧,讨论十八世纪微积分严格化的紧迫性,解释Euler、d’Alembert、Poisson和Lagrange所开创的数学技巧的发展过程,最后指出这些数学成果是如何被Cauchy用来建立新的严格微积分基础的. 相似文献
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The vibrational energy dependence of the rate of the gas phase reaction of Na with SF6 has been determined in a diffusion cloud experiment using CO2 laser excitation. The “conversion efficiency” of ca. 40% for vibrational energy suggests a preference for vibrational over the translational energy when compared with “prior” statistical expectation. 相似文献
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A partition of the positive integers into sets A and B avoids a set S N if no two distinct elements in the same part have a sum in S. If the partition is unique, S is uniquely avoidable. For any irrational > 1, Chow and Long constructed a partition which avoids the numerators of all convergents of the continued fraction for , and conjectured that the set S which this partition avoids is uniquely avoidable. We prove that the set of numerators of convergents is uniquely avoidable if and only if the continued fraction for has infinitely many partial quotients equal to 1. We also construct the set S and show that it is always uniquely avoidable. 相似文献
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Sandy Grabiner 《Proceedings of the American Mathematical Society》2004,132(6):1675-1684
Suppose that is a weighted convolution algebra on with the weight normalized so that the corresponding space of measures is the dual space of the space of continuous functions. Suppose that is a continuous nonzero homomorphism, where is also a convolution algebra. If is norm dense in , we show that is (relatively) weak dense in , and we identify the norm closure of with the convergence set for a particular semigroup. When is weak continuous it is enough for to be weak dense in . We also give sufficient conditions and characterizations of weak continuity of . In addition, we show that, for all nonzero in , the sequence converges weak to 0. When is regulated, converges to 0 in norm.