温度对渗铝层生长动力学的影响和稀土的行为研究     

张伟  白宇光  徐国辉  张金民 《洛阳工业高等专科学校学报》2008,18(2)

分别研究了工业纯铁在710℃、740℃、770℃条件下热浸镀纯铝和稀土铝后合金层厚度随浸镀时间的变化,将其代入化学热处理的基本经验公式,经一元线性回归处理,证明了合金层生长动力学为抛物线型,并且稀土对动力学各阶段都有影响。在710℃和740℃时稀土作用明显,在770℃时作用较弱。试验结果表明,稀土渗入了合金层,并使渗层增加25%～30%;扩散激活能分别降低3155J/mol、3712J/mol和1339J/mol。讨论了稀土在热浸镀铝中的行为。  相似文献   

肉鸡日粮中添加有机铬的试验     

王治华  陈俊东  汪招雄 《安徽科技学院学报》2002,16(4):12-13

选用300只1日龄艾维茵肉鸡,随机分为三组:A组为对照组,喂基础日粮;B和C组为试验组,分别在基础日粮中添加0.2和0.4mg/kg的烟酸铬.结果表明:在日粮中添加烟酸铬可以显著地降低肉鸡的腹脂率(P＜0.05),且有降低皮脂率的趋势(P＞0.05);同时能提高肉鸡在应激环境中的体重(P＜0.05).三组肉鸡的饲料利用率、胸腿肌率、屠宰率及成活率差异均不显著(P＞0.05).  相似文献   

Growth and diversity in doctoral education: assessing the Australian experience   总被引：2，自引：0，他引：2  

Margot Pearson  Terry Evans  Peter Macauley 《Higher Education》2008,55(3):357-372

The major growth of doctoral education in recent decades has attracted attention from policy makers and researchers. In this article we explore the growth of doctoral education in Australia, its impact on diversity in respect of the doctoral population, shifts in disciplinary strengths, institutional concentration and award programs. We conclude that there has been both change and continuity in the provision of doctoral education with extensive variation at the level of practice in what is a reasonably stable system featuring continuing hierarchical institutional diversification. The limitations of available data and issues for further research, policy and practice are discussed.

Peter MacauleyEmail:

  相似文献   

不同海拔地区交替训练对运动员GH和IGF-I的影响     

甘春龙  赵晋  徐杨  吴翠翠  李振华 《四川体育科学》2014,(1):28-32

目的：探讨不同海拔交替训练对运动员生长激素和胰岛素样因子-I的影响。方法：长期生活在平原的男子运动员19人,分为两组：高原-平原交替训练组和高原-亚高原交替训练组。采用放射免疫法测试血清生长激素和胰岛素样因子-I的变化情况。结论：（1）通过两个阶段的交替训练,两个组运动员的GH和IGF-I变化幅度减小,运动员对于低氧刺激的调节能力增强了,有利于运动员更好的适应训练。（2）高原-亚高原组第二阶段GH、IGF-I整体水平要高于高原-平原组,表明在亚高原训练后可以更好的过渡到高原进行训练,减少运动员的适应期,有利于运动员在高原期间的训练。  相似文献   

Measuring those who have their minds set: An item-level meta-analysis of the implicit theories of intelligence scale in education     

《Educational Research Review》2022

Fixed and growth mindsets represent implicit theories about the nature of one's abilities or traits. The existing body of research on academic achievement and the effectiveness of mindset interventions for student learning largely relies on the premise that fixed and growth mindsets are mutually exclusive. This premise has led to the common practice in which measures of one mindset are reversed and then assumed to represent the other mindset. Focusing on K-12 and university students (N = 27328), we tested the validity of this practice via a comprehensive item-level meta-analysis of the Implicit Theories of Intelligence Scale (ITIS). By means of meta-analytic structural equation modeling and network analysis, we examined (a) the ITIS item-item correlations and their heterogeneity across 32 primary studies; (b) the factor structure of the ITIS, including the distinction between fixed and growth mindset; and (c) moderator effects of sample, study, and measurement characteristics. We found positive item-item correlations within the sets of fixed and growth mindset items, with substantial between-study heterogeneity. The ITIS factor structure comprised two moderately correlated mindset factors ($\rho$ = 0.63–0.65), even after reversing one mindset scale. This structure was moderated by the educational level and origin of the student sample, the assessment mode, and scale modifications. Overall, we argue that fixed and growth mindsets are not mutually exclusive but correlated constructs. We discuss the implications for the assessment of implicit theories of intelligence in education.  相似文献