排序方式: 共有34条查询结果,搜索用时 20 毫秒
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Brienne N. Seiner Shannon M. Morley Tere A. Beacham Morgan M. Haney Stephanie Gregory Lori Metz 《Journal of Radioanalytical and Nuclear Chemistry》2014,302(1):673-678
The purpose of this work was to determine polonium losses from a variety of sample types (soil, cotton fiber, and air filter) due to digestion technique, chemical separation, and deposition method for alpha energy analysis. Results demonstrated that yields from a perchloric acid wet-ash (87 ± 5 %) were similar to that from a microwave digestion (100 ± 7 %), but both were greater than the dry-ash procedure (38 ± 5 %). The polonium was separated from an SRM soil using an AG1X8 ion exchange column and deposited on a Ag disk with a recovery of 83 ± 7 % of polonium-209 (Po-209). Deposition yields without chemical separation averaged 90 ± 5 % of Po-209. The polonium-210 content was successfully measured in the three matrix types and quantitated using alpha spectroscopy. 相似文献
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Trent D Lund Timothy W West Lilyan Y Tian Lihong H Bu Daniel L Simmons Kenneth DR Setchell Herman Adlercreutz Edwin D Lephart 《BMC neuroscience》2001,2(1):20-13
Background
In learning and memory tasks, requiring visual spatial memory (VSM), males exhibit superior performance to females (a difference attributed to the hormonal influence of estrogen). This study examined the influence of phytoestrogens (estrogen-like plant compounds) on VSM, utilizing radial arm-maze methods to examine varying aspects of memory. Additionally, brain phytoestrogen, calbindin (CALB), and cyclooxygenase-2 (COX-2) levels were determined. 相似文献6.
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Michal?Landa Petr?Sedlák Hanu??Seiner Luděk?Heller Lucie?Bicanová Petr??ittner Václav?Novák 《Applied Physics A: Materials Science & Processing》2009,96(3):557-567
Recent experimental and theoretical improvements of resonant ultrasound spectroscopy (RUS) are summarized to investigate elastic
constants of phases in shape memory alloys. The proposed inversion procedure, described in this work, is particularly suitable
to reliable evaluation of the temperature dependence of elastic constants of low-symmetry ferroelastic materials which may
be strongly elastically anisotropic and tend to exist in twinned forms. The method is applicable even for the evaluation of
single-crystal elastic constants from RUS measurements on microtwinned crystals, since it involves a homogenization algorithm
based on the macroscopic deformation response of the layered structure. This potentially allows performing meaningful acoustic
studies on samples with a general submicron-size layered structure. 相似文献
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Gee KL Atchley AA Falco LE Shepherd MR Ukeiley LS Jansen BJ Seiner JM 《The Journal of the Acoustical Society of America》2010,128(5):EL211-EL216
Bicoherence analysis has been used to characterize nonlinear effects in the propagation of noise from a model-scale, Mach-2.0, unheated jet. Nonlinear propagation effects are predominantly limited to regions near the peak directivity angle for this jet source and propagation range. The analysis also examines the practice of identifying nonlinear propagation by comparing spectra measured at two different distances and assuming far-field, linear propagation between them. This spectral comparison method can lead to erroneous conclusions regarding the role of nonlinearity when the observations are made in the geometric near field of an extended, directional radiator, such as a jet. 相似文献
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