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排序方式: 共有126条查询结果,搜索用时 15 毫秒
11.
本文通过对A-P方程作Mellin变换和对演化函数的Mellin变换结果作展开近似,求得了核子中价夸克极化分布函数随Q~2变化的解析表达式,并利用所得结果给出了核子中夸克自旋不对称量的一些理论预言  相似文献   
12.
Interspecies scaling factors (ISFs) are numbers used to adjust the potency factor (for example, the q1* for carcinogens or reference doses for compounds eliciting other toxic endpoints) determined in experimental animals to account for expected differences in potency between test animals and people. ISFs have been developed for both cancer and non-cancer risk assessments in response to a common issue: toxicologists often determine adverse effects of chemicals in test animals and then they, or more commonly risk assessors and risk managers, have to draw inferences about what these observations mean for the human population. This perspective briefly reviews the development of ISFs and their applications in health risk assessments over the past 20 years, examining the impact of pharmacokinetic principles in altering current perceptions of the ISFs applied in these health risk assessments, and assessing future directions in applying both pharmacokinetic and pharmacodynamic principles for developing ISFs.  相似文献   
13.
In this article, we present a general model to deal with the problem of matching multiple objects or configurations of points from a Bayesian point of view. We study both labeled and non labeled cases. Our model generalizes, in terms of non singular affine transformations and multiple configurations, previous two-terms matching models. As a practical application in Bioinformatics, we consider data from a microarray experiment of gorilla, bonobo, and human-cultured fibroblasts. We find out the matchings and the best affine transformation between the projections of genes on a two-dimensional space, obtained by a multidimensional scaling technique.  相似文献   
14.
Two similarity measures are employed to compare historic stock market indices over time. The more traditional Euclidean similarity is employed to provide a reference. As a comparison, dynamic time warping is introduced as a similarity measure. Multidimensional scaling is employed to compare these dissimilarities on 15 financial indices sampled daily over a 10-year period. In addition to investigating the whole period, 1-year tranches are also considered. This analysis is compared to a recent study of Machado et al. [Analysis of stock market indices through multidimensional scaling, Commun. Nonlinear Sci. Numer. Simul. 16(12) (2011), pp. 4610–4618], who examined these same indices using correlation as a similarity measure. It is suggested that this approach may be problematic. Doubt is also cast on the efficacy of the ‘histogram’ similarity they also propose.  相似文献   
15.
基于66种力学期刊论文的参考文献,利用引文分析法对力学期刊的引文进行统计和分析,得到力学期刊群的引文矩阵。通过余弦函数将引文矩阵转化为相似矩阵,并运用多维尺度分析法将力学期刊之间在引文上的相似性转化为平面距离,以平面图直观地展现出力学不同分支学科期刊子群在引文上的关系。在通过因子分析将66种力学期刊复杂的内部关系转换为少数几个不相关的因子的同时,考察了力学期刊群的构成和内部关系,从而探索了力学学科的结构。  相似文献   
16.
集中探讨了公益广告语中人称代词的认知心理,并分析了代词阶在公益广告语中的运用,指出受众基于自己的的知识框架,态度,价值观所形成的认知图式会对识解公益广告人称代词时的认知心理产生深刻的影响。  相似文献   
17.
ABSTRACT

China’s mobility turn has created the world’s largest public rail system, contributing extensively to citizens’ economic, social, and spatial mobility. Concurrently, this technological transformation has introduced many opportunities for individuation, which could potentially challenge the social, collectivistic, and Confucian foundations of China’s sociocultural and political ideology. While the notion that ‘mobility produces culture’ is readily accepted, research on train mobility in China is rare. In this study, we use Albert Bandura’s Model of Triadic Reciprocal Causation to conceptualize mobility as agency. We employ Hermeneutic Content Analysis, a mixed methods framework, to study how this rapidly evolving mobility environment connects to the lives of 31 regular train users living in Beijing. Studying agency in China enables us to systematize the sociocultural models within which mobility practices are embedded and how they manifest. We find that our interviewees embed agentive practices in a cultural model that is intertwined with collectivistic aspirations of the country. Technological developments are thus integrated into existing sociocultural models and political expectations, contradicting existing debates on the fracturing impact of disruptive technologies.  相似文献   
18.
在对数字图像的缩放原理进行理论分析的基础上,给出了适合工程应用的简化缩放公式,以数字自动印刷机为例,介绍了用硬件实现数字图像缩放的方法,并对数字图像经过缩放后产生的误差与失真进行了分析。  相似文献   
19.
A New Look at the Psychometric Paradigm of Perception of Hazards   总被引:1,自引:0,他引:1  
The psychometric paradigm has been the most influential model in the field of risk analysis. The "cognitive maps" of hazards produced by the paradigm seem to explain how laypeople perceive the various risks they face. Because most of the studies used aggregated data, analyzed using principal component analysis, it is not known whether the model neglects individual differences in risk perception. There has been much criticism on the fact that few studies have examined individual differences in the cognitive representation of hazards. In order to detect and describe the internal structure of the three-way data, we conducted a three-way component analysis (3MPCA). Data for the present analysis were derived from a mail survey conducted in Switzerland. Participants were asked to judge 9 attributes for 26 hazards. Individual differences in the cognitive representation of hazards were correlated with external variables (e.g., general trust). The results suggest that methods permitting individual differences should be used more frequently and that utilizing different methods could provide greater insight into the cognitive representation of risks.  相似文献   
20.
本文对彩色制版的关键设备——国产电子分色机作了简单介绍。提出了电子分色机的横向倍率缩放功能系统的实现方法及其设计方案,在设计方案中采用了锁相环及PWM脉宽调制器以及其他集成电路。  相似文献   
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