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991.
The short-range order (SRO) structure of a Au-25 at. pct Fe single crystal was studied using wide-angle diffuse synchrotron X-radiation scattering at room temperature. Two heat treatments were investigated: a 400 °C aging treatment for 2 days and a 440 °C treatment for 5 days, both preceded by solution treatment in the single-phase field and water-quenched to room temperature. Evolution of the SRO structure with aging was determined by fitting the two sets of Cowley-Warren (C-W) SRO parameters to a pair of 140,608-atom models. The microstructures, although quite disordered, showed a trend with aging for an increasing volume fraction of an Fe-enriched and an Fe-depleted environment. The Fe-enriched environment displayed a preference for Fe segregation to the {110} and {100} face-centered cubic (fcc) matrix planes. A major portion of the Fe-depleted environment was found to contain elements (and variations of these elements) of the Dla ordered superstructure. The SRO contained in the Fe-depleted environment may be best described in terms of the standing concentration wave packet (SCWP) model. This study provides, for the first time, a quantitative real-space view of the atomic arrangements, which make up both environments in the SRO structure of Au-25 at. pct Fe. Formerly Graduate Research Assistant, University of Illinois, Urbana, IL.  相似文献   
992.
993.
Magnetic resonance imaging allows a noninvasive assessment of myelination during normal brain maturation as well as the detection of genetically determined and acquired diseases that affect the synthesis and maintenance of myelin. If this high sensitivity of magnetic resonance imaging for white matter changes is completed by adequate clinical and biochemical information, a unique diagnostic tool is available to gain new insights in the formation of myelin and pathogenesis of myelin disorders.  相似文献   
994.
A rigorous analysis of the 80/20 rule is made using an index for the observed values of the variables. Three important findings are identified. First, a sufficient condition is provided for Burrell's inverse relationship between minimum holdings and average circulation rate. Second, an indexed version of Lotka's law is used to derive a sufficient condition for Egghe's finding on the 80/20 rule. Third, through the computer simulations of the Simon-Yule model of Lotka's law, we identify the entry rate of new holdings as well as the number of circulations when the entry rate is a decreasing function to be crucial factors for the pattern of the 80/20-type curve.  相似文献   
995.
多人决策的一类相对均衡解   总被引:1,自引:0,他引:1  
本文分析由于决策人偏好不同而引起决策差异的多人多目标决策问题,提出了这类决策问题的一类相对均衡解的概念和求取方法。相对均衡解以决策群体偏好的加权集结为基础,能最大程度地反映每个决策人的偏好。文中研究相对均衡解的SWT求取方法,并给出了求解的步骤。  相似文献   
996.
The mechanisms of apical (AP) uptake of cephalexin (CEPH) and loracarbef (LOR) in the absence or presence of an (extemally imposed) proton gradient were determined using well-stirred diffusion chambers that minimize the effects of the unstirred water layer. The results indicated that, compared to AP uptake in the presence of an imposed proton gradient, AP uptake in the absence of an imposed proton gradient had higher K(m) values and lower Jmax values. Furthermore, when inhibition studies were performed in the absence of a proton gradient, only natural peptides were effective, whereas the peptide analogs (e.g., enalapril) were not. In addition to the effects of concentration and competitive inhibitors, the results also indicated that (1) the AP uptake of both drugs was decreased more than 60% by FCCP, regardless of whether the proton gradient was present or absent; (2) effects of protein kinase C promoter were dependent upon the presence of a proton gradient; and (3) AP uptake in the presence of an imposed proton gradient was not affected by feeding restriction, whereas AP uptake in the absence of an imposed proton gradient was. These results showed for the first time that two substrates with similar AP uptake characteristics in the presence of an imposed proton gradient may not share those characteristics in the absence of an imposed proton gradient. Taken together, these results suggest that the AP uptake component that functions in the absence of an imposed proton gradient is distinctly different from the one that functions in the presence of an imposed proton gradient. Data generated from the present study and those in the literature lend support to the hypothesis that this distinctive component represents the second binding site on the AP peptide transporter. However, an alternative hypothesis that there are two AP peptide transporters remains to be disapproved.  相似文献   
997.
五强溪水电站主体工程混凝土浇筑垂直运输在大坝两岸分高、低层布置4台平移式20t缆索起重机。其中2台高缆从德国引进,属世界上首次采用全遥控的缆机,同时也是国内塔架最高的缆机;2台低缆属我国目前自行设计制造安装的规格最大、速度最高的缆机。  相似文献   
998.
The three-dimensional axisymmetric elastodynamic response of a penny-shaped crack embedded in an infinite elastic solid subjected to a pair of transient concentrated forces is investigated. The forces are applied on the symmetry axis perpendicular and symmetric to the crack surfaces, including the special case when the forces act precisely on the crack surfaces. A time-domain boundary integral equation method is applied for computing the crack-opening displacement and subsequently the time dependence of the dynamic stress intensity factors. Numerical calculations are carried out for various geometry parameters and the results are discussed. It is found that the location of the applied concentrated forces inducing the highest dynamic stress intensity factors differs from that producing the highest static values.  相似文献   
999.
The communicating finite state machines can exchange messages over bounded FIFO channels. In this paper, a new technique, called reverse reachability analysis, is proposed to detect deadlocks on the communication between the communicating finite state machines. The technique is based on finding reverse reachable paths starting from possible deadlock states. If a reverse reachable path can reach the initial global state, then deadlock occurs. Otherwise the communication is deadlock-free. The effectiveness of the technique has been verified by some real protocols such as a specification of X.25 call establishment/clear protocol and Bartlet's alternating bit protocol.  相似文献   
1000.
等距码的对偶距离分布及其性质   总被引:5,自引:2,他引:3  
本文主要讨论了等距码的对偶距离分布及其性质,然后利用这些性质将[1]中的某些结果推广到q元等距码情形,并得到了其对偶距离分布的递推关系式,最后,本文给出了q元等距码的码字数目的一个上界。  相似文献   
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