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221.
Brand MA Malinowski A Karimov OZ Marsden PA Harley RT Shields AJ Sanvitto D Ritchie DA Simmons MY 《Physical review letters》2002,89(23):236601
Optical spin-dynamic measurements in a high-mobility n-doped GaAs/AlGaAs quantum well show oscillatory evolution at 1.8 K consistent with a quasi-collision-free D'yakonov-Perel'-Kachorovskii regime. Above 5 K evolution becomes exponential as expected for collision-dominated spin dynamics. Momentum scattering times extracted from Hall mobility and Monte Carlo simulation of spin polarization agree at 1.8 K but diverge at higher temperatures, indicating the importance of electron-electron scattering and an intrinsic upper limit for the spin-relaxation rate. 相似文献
222.
On the basis of a study of the temperature-time dependence of polycaprolactam irradiated with thermal neutrons, it has been shown that strength and lifetime and the parameters which determine lifetime vary as functions of the radiation dose. 相似文献
223.
A study is made of the problem of two-dimensional radial displacement by gas of liquid from an unbounded uniform stratum. A comparison theorem is used to obtain lower and upper bounds for the pressure distribution. Calculations made using the obtained expressions showed that the difference between the upper and lower bounds is a fraction of a percent. Thus, in a calculation of the pressure a high degree of accuracy is achieved by using the lower bound for it.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 153–155, May–June, 1983. 相似文献
224.
A. Karimov M. F. Faskhutdinov N. D. Abdullaev M. G. Levkovich E. G. Mil'grom Ya V. Rashkes R. Shakirov 《Chemistry of Natural Compounds》1994,29(6):774-777
Berberine, palmatine, jatrorrhizine, oxyacanthine, berbamine, reticuline, obaberine, isocorydine, thalicmidine, and the new base berberal (I) have been isolated from leaves and young shoots ofBerberis heterobotrys Wolf. The structure of berberal has been established by a study of its1H and13C NMR spectra and measurement of intramolecular NOEs, and also by mass-spectrometric analysis.Institute of the Chemistry of Plant Substances, Uzbekistan Academy of Sciences, Tashkent. Andizhan State Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 869–873, November–December, 1993. 相似文献
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M. M. Yusupov A. Karimov R. Shakirov P. G. Gorovoi M. F. Faskhutdinov M. G. Levkovich N. D. Abdullaev 《Chemistry of Natural Compounds》1993,29(3):338-340
In addition to alkaloids isolated previously, young shoots of Berberis amurensis Rupr. have yielded berberrubine, oxyacanthine, and pseudopalmatine, and the new amorphous base amurenine. It's structure has been established on the basis of spectral characteristics and chemical transformations. 相似文献
230.
The flow of a chemically active fluid through a porous medium is considered. Under certain assumptions, an analytical solution is obtained which describes the distribution of the concentration of the chemically active component and the variation of the solidphase porosity. On the basis of the results obtained, the optimization of the hydrochloric acid treatment of wells is considered.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 78–81, March–April, 1985. 相似文献