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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44.
John Walton 《Surface and interface analysis : SIA》2007,39(4):337-342
Localised corrosion on a microchannel plate has been studied using X‐ray photoelectron spectromicroscopy. Curve fitting to the spectra at each pixel in the image data set reveals the presence of sodium and carbonate species at the corrosion sites, which optical microscopy suggests originated as droplets. It is proposed that aerosol contamination of the alkali enriched microchannel plate during removal of particulate material using a stream of compressed gas was responsible for the initiation of corrosion. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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Let H be a semisimple (so, finite dimensional) Hopf algebra over an algebraically closed field k of characteristic zero and let A be a commutative domain over k. We show that if A arises as an H-module algebra via an inner faithful H-action, then H must be a group algebra. This answers a question of E. Kirkman and J. Kuzmanovich and partially answers a question of M. Cohen. 相似文献
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A note on finding clothoids 总被引:2,自引:0,他引:2
The clothoid is a spiral that is used as transition curve in highway and railway route design. Although its defining formulas are transcendental functions, recent work has shown that it can be used fairly easily on small computers. A single nonlinear equation must be solved in each of four common arrangements of the clothoid. The purpose of this work is to give starting intervals for which Newton's root finding method applied to those equations is guaranteed to converge. 相似文献
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Electrochemical methods can be applied in a number of ways as detection systems for competitive immunoassays, especially through the use of redox-labelled antigens. To overcome the problem of detection of such conjugates at low concentration, a system is described in which a poly(vinylferrocene)-modified glassy carbon electrode is used to accumulate charge from solution glucose/glucose oxidase via the intermediacy of a redox-labelled antigen, cycled repeatedly between the enzyme and the electrode. The charge accumulated by the electrode is measured electrochemically by returning the electrode to its original potential and integrating the resulting current-time transient. The charge is proportional to the concentration of redox-labelled antigen in solution and to the charge-accumulation time. In this way 1,1'-dimethylferrocene-ethan-1-ol-2-amine was reproducibly detected to 0.9 nM, with a 10 min incubation period. The 8-ferrocenyl conjugate of theophylline was characterised as a model system for possible application in a higher sensitivity electrochemical immunoassay. 相似文献
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Abstract. Angiotensin is readily inactivated by ultraviolet light presumably due to the photosensitivity of its tyrosyl and phenylalanyl residues. Alkalinity promotes and acidity delays the biological decomposition. Under conditions of oxygen exclusion (i.e. under N2 or H2 ) the rate of decomposition is further depressed and when irradiation is carried out under hydrogen a biologically active product is formed. This altered angiotensin, judging from its chromatographic migration and dialysis rate, represents a polymerized form of angiotensin. Under identical irradiation conditions, angiotensin was coupled with C14 labelled pheny-lalanine which indicates that this residue might be the photoreactive species. The production of altered forms of angiotensin by ultraviolet irradiation was discussed with respect to possible utility in anti-metabolite, antigen or tracer work. 相似文献