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排序方式: 共有122条查询结果,搜索用时 15 毫秒
11.
A note on an inverse problem for nonnegative matrices 总被引:5,自引:0,他引:5
12.
M.J. Corden G.F. Cox D.P. Kelsey C.A. Lawrence P.M. Watkins O. Hamon J. Le Guyader J.M. Levy G.W. London 《Nuclear Physics B》1979,155(1):13-38
The differential and channel cross sections have been measured for the reactions KL0p → KS0p and KL0p → Λ0π+ in nine energy intervals in the c.m. range 1605 to 1910 MeV. The regeneration reaction is a combination of the KN amplitudes (with I = 0 and 1) and the amplitude (I = 1) and is very sensitive to the various KN phase-shift solutions, some of which show an exotic I = 0, P1 resonance. Our results have been expressed in terms of frequency distributions and cross sections, normalised by the Λ0π+ reaction. These results have been compared with the predictions of various partial-wave analyses. Qualitatively we can eliminate the P1 non-resonant solution, though no solution correctly predicts our results. 相似文献
13.
Sarah E London Yuichiro Itoh Valentin A Lance Petra M Wise Preethika S Ekanayake Randi K Oyama Arthur P Arnold Barney A Schlinger 《BMC neuroscience》2010,11(1):47
Background
Steroids affect many tissues, including the brain. In the zebra finch, the estrogenic steroid estradiol (E2) is especially effective at promoting growth of the neural circuit specialized for song. In this species, only the males sing and they have a much larger and more interconnected song circuit than females. Thus, it was surprising that the gene for 17β-hydroxysteroid dehydrogenase type 4 (HSD17B4), an enzyme that converts E2 to a less potent estrogen, had been mapped to the Z sex chromosome. As a consequence, it was likely that HSD17B4 was differentially expressed in males (ZZ) and females (ZW) because dosage compensation of Z chromosome genes is incomplete in birds. If a higher abundance of HSD17B4 mRNA in males than females was translated into functional enzyme in the brain, then contrary to expectation, males could produce less E2 in their brains than females. 相似文献14.
Background
Steroids are small molecule hormones derived from cholesterol. Steroids affect many tissues, including the brain. In the zebra finch, estrogenic steroids are particularly interesting because they masculinize the neural circuit that controls singing and their synthesis in the brain is modulated by experience. Here, we analyzed the zebra finch genome assembly to assess the content, conservation, and organization of genes that code for components of the estrogen-synthetic pathway and steroid nuclear receptors. Based on these analyses, we also investigated neural expression of a cholesterol transport protein gene in the context of song neurobiology. 相似文献15.
David London 《Linear and Multilinear Algebra》2013,61(3):179-189
Let L be a linear transformation on the set of all n×n matrices over an algebraically closed field of characteristic 0. It is shown that if AB=BA implies L(A)L(B)=L(B)L(A) and if either L is nonsingular or the implication in the hypothesis can also be reversed, then L is a sum of a scalar multiple of a similarity transformation and a linear functional times the identity transformation. 相似文献
16.
Froula DH Divol L Berger RL London RA Meezan NB Strozzi DJ Neumayer P Ross JS Stagnitto S Suter LJ Glenzer SH 《Physical review letters》2008,101(11):115002
We demonstrate a significant reduction of stimulated Brillouin scattering by polarization smoothing in large-scale high-temperature hohlraum plasma conditions where filamentation is measured to be negligible. The stimulated Brillouin scattering experimental threshold (defined as the intensity at which 5% of the incident light is backscattered) is measured to increase by a factor of 1.7+/-0.2 when polarization smoothing is applied. An analytical model relevant to inertial confinement fusion plasma conditions shows that the measured reduction in backscatter with polarization smoothing results from the random spatial variation in polarization of the laser beam, not from the reduction in beam contrast. 相似文献
17.
A. Ratkiewicz L. Berzak Hopkins D. L. Bleuel W. S. Cassata C. Cerjan L. Dauffy R. London D. Meeker C. A. Velsko C. B. Yeamans 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(1):169-175
The international monitoring system exists to verify compliance with the terms of the comprehensive test ban treaty. About 10% of the member stations will be capable of detecting radioxenon, which can be produced in nuclear detonations or through civilian processes. We have studied the activation of radioxenon by the prompt, intense spectrum of 14-MeV neutrons produced at the National Ignition Facility. While 14-MeV neutrons are not currently a significant contributor to the production of radioxenon, we find that radioxenon produced through activation of environmental xenon by 14-MeV neutrons would be distinguishable from activation by nuclear tests. 相似文献
18.
19.
We review the salient features of a comparative study of the profile of the CKM unitarity triangle, and the resulting CP-violating phases , β and γ in B decays, in the standard model and in several variants of the minimal supersymmetric standard model (MSSM), reported recently by us. These theories are characterized by a single phase in the quark flavour mixing matrix and give rise to well-defined contributions in the flavour-changing-neutral-current transitions in K and B decays. We analyse the supersymmetric contributions to the mass differences in the Bd0–
and Bs0–
systems, ΔMd and ΔMs, respectively, and to the CP-violating quantity || in K decays. Our analysis shows that the predicted ranges of β in the standard model and in MSSM models are very similar. However, precise measurements at B-factories and hadron machines may be able to distinguish these theories in terms of the other two CP-violating phases and γ. 相似文献
20.
Review of nanofluids for heat transfer applications 总被引:2,自引:0,他引:2
Saeid Vafaei 《中国颗粒学报》2009,7(2)
Research on nanofluids has progressed rapidly since its enhanced thermal conductivity was first repotted about a decade ago,though much controversy and inconsistency have been reported,and insufficient understanding of the formulation and mechanism of nanofluids further limits their applications.This work presents a critical review of research on heat transfer applications of nanofluids with the aim of identifying the limiting factors so as to push forward their further development. 相似文献