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1.
Concreteness fading has been proposed as a general instructional approach to support learning of abstract mathematics and science concepts. Accordingly, organizing external knowledge representations in a three-step concrete-to-idealized sequence should be more beneficial than the reverse, concreteness introduction, sequence. So far, evidence for the benefits of concreteness fading come mainly from studies investigating learning of basic mathematics concepts. Studies on learning natural science concepts are scarce and have not implemented the full three-step-sequence. In an experimental classroom study (N = 70), we compared concreteness fading and concreteness introduction in high school science education about electromagnetic induction using a detailed assessment. Furthermore, we explored whether these sequences differentially affect the use of the different representations during instruction. Both sequences were equally effective and there were no differences in using the representations. We discuss why our results question the proposed advantages of concreteness fading and highlight conceptual differences and learning goals across domains. 相似文献
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David C. Nieman 《运动与健康科学(英文)》2012,1(1):12-17
Maintaining leanness and a physically active lifestyle during adulthood reduces systemic inflammation, an underlying factor in multiple chronic diseases. The anti-inflammatory influence of near-daily physical activity in lowering C-reactive protein, total blood leukocytes, interleukin-6, and other inflammatory cytokines may play a key role in lowering risk of cardiovascular disease, certain types of cancer, type 2 diabetes, sarcopenia, and dementia. Moderate exercise training causes favorable perturbations in immunity and a reduction in incidence of upper respiratory tract infection (URTI). During each bout of moderate exercise, an enhanced recirculation of immunoglobulins, neutrophils, and natural killer cells occurs that persists for up to 3-h post-exercise. This exercise-induced surge in immune cells from the innate immune system is transient but improves overall surveillance against pathogens. As moderate exercise continues on a near-daily basis for 12–15 weeks, the number of symptoms days with URTI is decreased 25%–50% compared to randomized sedentary controls. Epidemiologic and animal studies support this inverse relationship between URTI risk and increased physical activity. 相似文献
3.
对赤水河上游国家级鱼类保护区内的墨头鱼标本进行了年龄鉴定,渔获物的年龄结构由0～8龄共9个龄组组成,以低龄个体为主,2～5龄个体占83.07%。体长和体质量呈幂函数关系且幂指数接近3,属于匀速生长类型,因此用Von Bertalanffy方程描述其生长特性,相关生长参数分别为:渐近体长L∞=323.0227mm,渐近体质量W∞=824.7102g,k=0.1781,t0=-1.4655龄。体质量生长拐点年龄Ti=4.77龄,对应体长、体质量分别为Lt=333.14mm,Wt=746.06g。由于捕获物中以低龄个体为主,呈现小型化趋势,建议将其捕捞年龄确定为5龄以保护核心区内的墨头鱼资源。 相似文献
4.
教师作为引导学生主动探究学习的“指路人”,应当把实现数学课堂有效教学、培养学生综合学习能力作为一项基本的教学目标。尤其是小学高年级学生,他们已经具备基础的数学运算能力,因此教师要进一步提高他们的数学学习能力,为后续的数学学习道路夯实基础。本文将浅谈如何更好地进行小学高年级数学应用题有效教学。 相似文献
5.
买买提艾力·喀迪尔 《喀什师范学院学报》2011,32(6):13-14,35
一个S-集必定是不规则集,除非S是整数.但S是整数的时候这个S-集可能是规则的,也可能是不规则的.为此,利用上密度和下密度来证明一个平面1-集的不规则性. 相似文献
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卢自娟 《赣南师范学院学报》2010,31(3):14-17
研究一种直径趋于无穷大的图类K2,r-单路图,利用图谱理论和高等数学求极限的方法,求得当点数n趋于无穷时,K2,r-单路图的谱半径有极限,并且求出了该极限值.进一步验证了该极限值即为K2,r-单路图的一个上界. 相似文献
8.
《Research Policy》2019,48(7):1681-1693
Only recently have enough women joined senior leadership positions in high tech firms for research on senior management gender diversity in high tech industries to be possible. We propose that senior management gender diversity fosters strategic change in high tech firms, especially under conditions where alliance formation intensity and top management team (TMT) educational background diversity are high, because the breadth of opportunity and knowledge associated with these conditions facilitates implementation of new ideas. Results show that both inter-organizational strategic alliance formation intensity and TMT educational background diversity positively moderate the relationship between senior management gender diversity and strategic change. We also find support for a moderated mediation model whereby a gender-diverse senior management positively impacts strategic change, which ultimately improves firm performance when the firm exhibits high alliance formation intensity and has a TMT that is diverse across educational background. 相似文献
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为解决一个随机变量的一阶矩的最优上界问题,本文通过对该随机变量分布列及对几种计算一阶矩的方法的研究和分析,找到一个比原上界更好的上界;同时对该随机变量的参数p,k研究进一步对该上界进行改进,找到一些满足特定条件的特殊上界。 相似文献