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C. D. Litton 《The Journal of the Operational Research Society》1983,34(12):1222-1223
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D.C. Reynolds D.W. Langer C.W. Litton G.L. McCoy K.K. Bajaj 《Solid State Communications》1983,46(6):473-476
A self-reversal model is presented to explain the luminescence dependence of the donor bound exciton intensity. The line broadening mechanism is attributed to rotational interaction with non-rigid rotator states. Line reversal results from absorption by non-broadened states near the crystal surface. The absence of a similar excitation intensity dependence for acceptor bound excitons is explained. 相似文献
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D.C. Reynolds C.W. Litton E.B. Smith P.W. Yu K.K. Bajaj 《Solid State Communications》1982,42(11):827-830
Recombination radiation due to an exciton bound to neutral donors and neutral acceptors in high purity vapor phase epitaxial GaAs is investigated using high resolution photoluminescence spectroscopy at liquid helium temperatures. It is found that those samples which show the presence of germanium acceptors also exhibit a strong residual donor referred to in the literature as X3. Samples containing carbon acceptors however, do not show the presence of X3. In the past X3 has been identified by some groups as due to carbon on the gallium site. The work presented here sugests that the X3 donor is associated with germanium. This identification of the X3 donor is in agreement with a recent assignment based on the far infrared study of neutron transmuted GaAs. 相似文献
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Through studies on [C6H6]+ and [C6H5]+ it is shown that charge stripping provides information on ion structure which is complementary to that given by collision-induced dissociation. Stripping involves a more uniform sampling over the range of ion internal energies than does collision-induced dissociation which preferentially samples higher energy ions. 相似文献
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Elisabeth CW van Straaten Willem de Haan Hanneke de Waal Philip Scheltens Wiesje M van der Flier Frederik Barkhof Ted Koene Cornelis J Stam 《BMC neuroscience》2012,13(1):1-7
Background
This study examined the effects of dietary polyunsaturated fatty acids (PUFA) as different n-6: n-3 ratios on spatial learning and gene expression of peroxisome- proliferator-activated receptors (PPARs) in the hippocampus of rats. Thirty male Sprague?CDawley rats were randomly allotted into 3 groups of ten animals each and received experimental diets with different n-6: n-3 PUFA ratios of either 65:1, 22:1 or 4.5:1. After 10?weeks, the spatial memory of the animals was assessed using the Morris Water Maze test. The expression of PPAR?? and PPAR?? genes were determined using real-time PCR.Results
Decreasing dietary n-6: n-3 PUFA ratios improved the cognitive performance of animals in the Morris water maze test along with the upregulation of PPAR?? and PPAR?? gene expression. The animals with the lowest dietary n-6: n-3 PUFA ratio presented the highest spatial learning improvement and PPAR gene expression.Conclusion
It can be concluded that modulation of n-6: n-3 PUFA ratios in the diet may lead to increased hippocampal PPAR gene expression and consequently improved spatial learning and memory in rats. 相似文献10.