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41.
The chemical synthesis and NMR characterization of the benzo ring tetrahydro- and diol epoxides of the carcinogen benz[c]acridine are described. 相似文献
42.
S. K. Srivastava 《International Journal of Theoretical Physics》1995,34(1):109-125
Expressions for the time dependence of the fundamental constants are derived through dimensional reduction and one-loop quantum corrections to scalar fields. Moreover, singularity-free solutions of Einstein's field equations are obtained. Using these solutions, we discuss the time dependence of fundamental constants. It is interesting to see that the fine structure constant asymptotically approaches to 1/137,G
eff (effective four-dimensional constant) approachesG
N (Newtonian gravitational constant), and eff vanishes. Graphical representations of these results are also given for a special case. 相似文献
43.
The total and differential cross sections for the electron and positron impact excitation of hydrogen from its initially excited metastable 22S state to 32S and 32P states are reported. A distorted-wave approximation theory is used for the calculation. The angular correlation parameters, Ly and alignment angle are also reported for 22S-32P excitation. For comparison, similar first Born results are also obtained. Interesting features are noted on comparing our distorted wave results with the first Born results as well as with the other available results forn
2S andn
2P (n=2,3) excitations from the ground 12S state of hydrogen. 相似文献
44.
45.
G. S. Srivastava 《分析论及其应用》1996,12(4):96-104
The regular solutions of generalized axisymmetric potential equation
, a>−1/2 are called generalized axisymmetric potentials. In this paper, the characterizations of lower order and lower type
of entire GASP in terms of their approximation error {En} have been obtained. 相似文献
46.
47.
48.
49.
Numerical simulations are done of Langevin dynamics for a uniform-orderparameter, field-swept Landau model,= –|a/2|m
2+|b/4|m
4–mh(t) , to study hysteresis effects. The field is swept at a constant rateh(t)=h(0)+ht. The stochastic jump values of the field {hJ from an initially prepared metastable minimumm(0) are recorded, on passage to a global minimum m(). The results are: (a) The mean jump¯h
J(h) increases (hysteresis loop widens) with h, confirming a previous theoretical criterion based on rate competition between field-sweep and inverse mean first-passage time (FPT); (b) The broad jump distribution(h
J,h) is related to intrinsically large FPT fluctuations (
2–2)/
2 O(1), and can be quantitatively understood. Possible experimental tests of the ideas are indicated. 相似文献
50.