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排序方式: 共有251条查询结果,搜索用时 62 毫秒
61.
R. Weigand G. Bacher V. D. Kulakovskii J. Seufert T. Kümmell A. Forchel K. Leonardi D. Hommel 《Physica E: Low-dimensional Systems and Nanostructures》2000,7(3-4)
The eigenstate symmetry in CdSe/ZnSe single quantum dots (SQDs) has been studied by low-temperature magnetoluminescence spectroscopy. Regarding both, the fine structure splitting and the polarization properties of the biexciton transition, the influence of exchange and Zeeman interaction on the eigenstate symmetry of the final state of recombination, the ground state of the single exciton, is investigated. 相似文献
62.
The effect of cellular energetics on foreign protein production 总被引:1,自引:0,他引:1
Yun-Fei Ko William E. Bentley William A. Weigand 《Applied biochemistry and biotechnology》1995,50(2):145-159
Escherichia coli strain F-122 was used to determine if there are additional physiological effects, other than decreasing energetic efficiency
accompanied by the excretion of the acetate, on foreign protein production. This organism was the host for expressing HIV582-β-galactosidase fusion protein under the control of thetrp promoter, with ampicillin resistance. By comparing parallel batch cultures with and without acetate addition, it was found
that the presence of acetate in the media did not influence β-galactosidase activity. In these experiments, it appears that
the low protein productivity often observed during acetate formation is the result of inefficient cell metabolism, rather
than acetate acting as a specific inhibitor of protein production. 相似文献
63.
64.
Brand H Mayer P Polborn K Schulz A Weigand JJ 《Journal of the American Chemical Society》2005,127(5):1360-1361
Explosive alkali dinitrosomethanides (M[HC(NO)2]; M = Li, Na, K, Cs) were prepared in a new, simple, high-yielding synthetic procedure, fully characterized, and shown to be stable at ambient temperature. Alkali dinitrosomethanides are of widespread interest to pharmaceutical and materials scientists alike. 相似文献
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66.
H. -J. Schneider W. Gschwendtner und E. F. Weigand 《Fresenius' Journal of Analytical Chemistry》1980,304(4):282
Ohne Zusammenfassung
Molecular-mechanic force field calculations and steric effects on 13C NMR shifts for selected alicycles, bicycles and steroids. Comparison with NMR and X-Ray crystal structure data相似文献
67.
The statistical perturbations of γγ-angular correlations involving the first 2+ rotational state of154Gd and156Gd have been time differentially investigated. We used liquid sources of 3+ ions of Gadolinium in lN perchloric acid, 0.5 N and 1N hydrochloric acid, 1.3N and 2.6 N sulfuric acid. Influences of the various chemical surroundings on the ratio λ4/λ2 of the attenuation parameters have been found. A simultaneous measurement of the angular correlation of the 874 keV–123 keV cascade and the 2,098 keV–89 keV cascade of154Gd and156Gd, respectively, has been performed in perchloric solution. From the ratio of the attenuation parameters λ2, obtained by this experiment, we have derived the ratio of the magneticg-factors of the first 2+ levels of these isotopes asg 154/g 156=1.11±0.08. 相似文献
68.
69.
Film cooling on a convex surface: influence of external pressure gradient and Mach number on film cooling performance 总被引:1,自引:0,他引:1
The film cooling performance on a convex surface subjected to zero and favourable pressure gradient free-stream flow was
investigated. Adiabatic film cooling effectiveness values were obtained for five different injection geometries, three with
cylindrical holes and two with shaped holes. Heat transfer coefficients were derived for selected injection configurations.
CO2 was used as coolant to simulate density ratios between coolant and free-stream close to gas turbine engine conditions. The
film cooling effectiveness results indicate a strong dependency on the free-stream Mach number level. Results obtained at
the higher free-stream Mach number show for cylindrical holes generally and for shaped holes at moderate blowing rates significant
higher film cooling effectiveness values compared to the lower free-stream Mach number data. Free-stream acceleration generally
reduced adiabatic film cooling effectiveness relative to constant free-stream flow conditions. The different free-stream conditions
investigated indicate no significant effects on the corresponding heat transfer increase due to film injection. The determined
heat flux ratios or film cooling performance indicated that coolant injection with shaped film cooling holes is much more
efficient than with cylindrical holes especially at higher blowing rates. Heat flux penalties can occur at high blowing rates
when using cylindrical holes.
Received on 29 May 2000 相似文献
70.