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61.
Cellular precipitation (also known as discontinuous precipitation) has been observed at the grain boundaries of a newly developed nickel-based Inconel740H alloy designed for use at 700?°C in advanced ultrasupercritical coal-fired power plants. By means of element mapping and selected area diffraction, the cellular precipitates were identified as Cr-rich M23C6 carbides. The onset of cellular precipitation was found to follow a pucker mechanism in Inconel740H. The cellular precipitates at the grain boundaries, even at low volume fractions, were severely detrimental to the creep strength at 750?°C. The creep rupture life of Inconel740H containing cellular precipitates at grain boundaries was only one-tenth of that for the alloy without cellular precipitates. The reason for the drastically decreased creep rupture life is attributed to the poor resistance of cellular precipitates to crack propagation during creep.  相似文献   
62.
现代肿瘤的诊疗水平已经有了长足的进步,先进的诊断技术使得很多肿瘤得以早期发现并积极治疗,很多晚期患者也不再面临无药可用的境地,但由于临床医生的认识存在偏差,存在过度诊断和过度治疗的问题,进而给患者带来不必要的负担和痛苦。美国临床肿瘤学会(ASC0)年会上发布了一篇名为“ASCO为改善肿瘤治疗质量及医疗花费的5项建议”的文章,特别提出要重视五项临床广泛应用、花费较大,但缺乏高级临床证据的肿瘤治疗或干预措施,也提示我们需要充分评估,综合思考,为合适的患者提供正确的诊治方案,才能给患者带来更大的获益。  相似文献   
63.
Sketching is widely used in design to generate creative ideas. Design studies present stimuli during sketching to enhance creativity. This study examines the effect of stimuli presented during different sketching states, especially of those presented during the stuck period. It conducted a sketching experiment that enrolled 41 students with an average of 5.7 years’ practice in industrial design. The sketching with stimuli presented at regular intervals, those with stimuli presented during the stuck period, and those without stimulus were compared. Eye movements during the sketching processes were recorded. The attention to stimuli, and the direct applications of stimuli to design ideas, and the idea connection and idea differentiation were analyzed. Participants sketching with stimuli presented during the stuck period had a higher sketching quality, compared with those in other experimental conditions. They fixated longer on stimuli, built more links among related ideas, and had a more differentiated and balanced exploration. This study then proposed the mechanisms of stimuli processing. The stimuli presented at regular intervals were stored and acted as additional memory. The stimuli presented during the stuck period were dissected and acted as supporter, inducing a more creative sketching.  相似文献   
64.
The purpose of this study is to discuss the dynamic interdependence of knowledge and economic growth. We show that the traditional economics, which treats knowledge as parameters and is mainly developed within linearized, stable and static frameworks can hardly explain the modern economic complexity. We argue that it is necessary to treat creativity, learning and knowledge utilization as endogenous dynamic processes of social and economic evolution. To handle with the complicated dynamic interdependence of wealth and knowledge accumulation, we need to apply genuine nonlinear dynamic theory. In particular, we discuss possible benefits of government's intervention in education and science to the society when the social and economic evolution is characterized of nonlinearity, instability and multi‐equilibria.  相似文献   
65.
Although the state space approach for estimating multilevel regression models has been well established for decades in the time series literature, it does not receive much attention from educational and psychological researchers. In this article, we (a) introduce the state space approach for estimating multilevel regression models and (b) extend the state space approach for estimating multilevel factor models. A brief outline of the state space formulation is provided and then state space forms for univariate and multivariate multilevel regression models, and a multilevel confirmatory factor model, are illustrated. The utility of the state space approach is demonstrated with either a simulated or real example for each multilevel model. It is concluded that the results from the state space approach are essentially identical to those from specialized multilevel regression modeling and structural equation modeling software. More importantly, the state space approach offers researchers a computationally more efficient alternative to fit multilevel regression models with a large number of Level 1 units within each Level 2 unit or a large number of observations on each subject in a longitudinal study.  相似文献   
66.
This study investigated the sensitivity of fit indices to model misspecification in within-individual covariance structure, between-individual covariance structure, and marginal mean structure in growth curve models. Five commonly used fit indices were examined, including the likelihood ratio test statistic, root mean square error of approximation, standardized root mean square residual, comparative fit index, and Tucker-Lewis Index. The fit indices were found to have differential sensitivity to different types of misspecification in either the mean or covariance structures with severity of misspecification controlled. No fit index was always more (or less) sensitive to misspecification in the marginal mean structure relative to those in the covariance structure. Specifying the covariance structure to be saturated can substantially improve the sensitivity of fit indices to misspecification in the marginal mean structure; this result might help identify the sources of specification error in a growth curve model. An empirical example of children's growth in math achievement (Wu, West, &; Hughes, 2008 Wu, W., West, S. G. and Hughes, J. N. 2008. Effect of retention in first grade on children's achievement trajectories over four years: A piecewise growth analysis using propensity score matching.. Journal of Educational Psychology, 100: 727740. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]) was used to illustrate the results.  相似文献   
67.
焦虑与注意偏向的研究是近年来情绪与认知领域的热点。为探讨特质焦虑个体的注意偏向特点及其返回抑制能力是否受不同线索的调节, 采用特质焦虑量表筛选高特质焦虑大学生29名, 低特质焦虑大学生28名完成线索-靶子任务。要求被试在提示线索消失后, 对位置进行快而准地辨别反应, 分别探索中性和情绪性提示线索下被试的返回抑制。结果发现:(1)在中性线索条件下, 高焦虑个体平均反应时慢于低焦虑个体。(2) 在情绪线索条件下, 高焦虑个体在负性线索下的反应时小于在正性线索下的反应时; 高、低焦虑个体在各种SOA条件下均出现了返回抑制, 但各组返回抑制量受到情绪线索的调节:在正性情绪线索条件下, 两组返回抑制量没有显著差异; 在负性情绪线索下, 高焦虑个体返回抑制量显著小于低焦虑个体。这表明, (1)焦虑个体的注意偏向受到刺激信息的影响:只对负性情绪线索出现注意警觉; (2)只有在涉及负性情绪信息时高、低焦虑个体返回抑制能力才有差异, 高焦虑个体存在对负性情绪线索的抑制困难。  相似文献   
68.
Animals may memorise spatial and social information for many months and even years. Here, we investigated long-term memory of hierarchically ordered relationships, where the position of a reward depended on the relationship of a stimulus relative to other stimuli in the hierarchy. Seventeen greylag geese (Anser anser) had been trained on discriminations between successive pairs of five or seven implicitly ordered colours, where the higher ranking colour in each pair was rewarded. Geese were re-tested on the task 2, 6 and 12 months after learning the dyadic colour relationships. They chose the correct colour above chance at all three points in time, whereby performance was better in colour pairs at the beginning or end of the colour series. Nonetheless, they also performed above chance on internal colour pairs, which is indicative of long-term memory for quantitative differences in associative strength and/or for relational information. There were no indications for a decline in performance over time, indicating that geese may remember dyadic relationships for at least 6 months and probably well over 1 year. Furthermore, performance in the memory task was unrelated to the individuals’ sex and their performance while initially learning the dyadic colour relationships. We discuss possible functions of this long-term memory in the social domain.  相似文献   
69.
Empirical studies have validated that basic needs satisfaction supported by video game play predicts motivation and engagement outcomes. However, few studies specifically manipulated game features for each of the three basic needs specified in the self-determination theory (SDT) to examine how the game features impact players' need satisfaction and game experience. The current study employed an in-house developed exergame and manipulated the game features in a 2 (autonomy-supportive game features: on vs. off) × 2 (competence-supportive game features: on vs. off) experiment to predict need satisfaction, game enjoyment, motivation for future play, effort for gameplay, self-efficacy for exercise using the game, likelihood of game recommendation, and game rating. The manipulated game features led to the corresponding need satisfaction. Manipulated autonomy-supportive and competence-supportive game features had main effects on most motivation and engagement outcomes. Need satisfaction of autonomy and need satisfaction of competence were both found to be mediators for the relationships between the game features and the motivation and engagement outcomes. The findings add evidence to support the underlying mechanism postulated by SDT for media enjoyment and motivation as well as the emerging entertainment research conceptualizing enjoyment as need satisfaction. The findings also have practical implications for intervention effort that intends to capitalize the motivational pull of video games.  相似文献   
70.
This study examines the indirect effects of extensive negative political attack ads in the 2004 presidential election from a third-person effects perspective. Results of a survey using a probability sample of 496 college students indicate that these students believe attack ads harm others more than themselves. Moreover, the respondents tended to perceive attack ads in traditional media to have a greater harmful effect on self and others than attack ads on the Internet. Contingent factors that account for the magnitude of third-person effects include social distance and knowledge. Further, exposure to attack ads was found to be the strongest predictor of perceived harms of such ads on self and others, but only perceived harm on others is a significant predictor of support for restrictions on attack ads. The study contributes to research on the third-person effect by testing perceived harms of attack ads on self and others separately on likelihood to support restrictions.  相似文献   
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