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21.
Suárez-Orozco Carola; Gaytán Francisco X.; Bang Hee Jin; Pakes Juliana; O'Connor Erin; Rhodes Jean 《Canadian Metallurgical Quarterly》2010,46(3):602
Immigration to the United States presents both challenges and opportunities that affect students' academic achievement. Using a 5-year longitudinal, mixed-methods approach, we identified varying academic trajectories of newcomer immigrant students from Central America, China, the Dominican Republic, Haiti, and Mexico. Latent class growth curve analysis revealed that although some newcomer students performed at high or improving levels over time, others showed diminishing performance. Multinomial logistic regressions identified significant group differences in academic trajectories, particularly between the high-achieving youth and the other groups. In keeping with ecological–developmental and stage–environment fit theories, School Characteristics (school segregation rate, school poverty rate, and student perceptions of school violence), Family Characteristics (maternal education, parental employment, and household structure), and Individual Characteristics (academic English proficiency, academic engagement, psychological symptoms, gender, and 2 age-related risk factors, number of school transitions and being overaged for grade placement) were associated with different trajectories of academic performance. A series of case studies triangulate many of the quantitative findings as well as illuminate patterns that were not detected in the quantitative data. Thus, the mixed-methods approach sheds light on the cumulative developmental challenges that immigrant students face as they adjust to their new educational settings. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Jihoon Park Hyun-Woo Shin Joona Bang June Huh 《International journal of molecular sciences》2022,23(10)
The order-disorder transitions (ODT) of core-shell bottle brush copolymer and its structural isomers were investigated by dissipative particle dynamics simulations and theoretically by random phase approximation. Introducing a chain topology parameter which parametrizes linking points between M diblock chains each with N monomers, the degree of incompatibility at ODT (; being the Flory–Huggins interaction parameter between constituent monomers) was predicted as a function of chain topology parameter () and the number of linked diblock chains per bottle brush copolymer (M). It was found that there exists an optimal chain topology about at which gets a minimum while the domain spacing remains nearly unchanged. The prediction provides a theoretical guideline for designing an optimal copolymer architecture capable of forming sub-10 nm periodic structures even with non-high components. 相似文献
24.
不规则样品中元素含量XRF测定的校正 总被引:1,自引:0,他引:1
介绍了当样品的被测底面积不能视为无限大时目标元素含量的测量方法。从理论上说明了特散比R是与样品的被测量底面积无关的参数,通过实验证明特散比法是解决不规则样品中元素含量测量问题的很有效方法。 相似文献
25.
不平衡数据集类别分布严重倾斜,传统的聚类算法由于以提高整体学习性能为目标,往往偏向于聚集多数类,而忽视更有价值的稀有类.本文提出一种基于迭代的特征加权聚类算法,根据当前聚类后簇的特点以及特征重要性度量函数确定特征权值,利用所得权值进行下一轮聚类,直到权值稳定后结束迭代.在多个UCI不平衡数据集上的实验效果表明,本文算法能够较好地识别出重要特征并提高它们的权重,避免聚类算法过度偏向多数类,有效地提高了聚类性能. 相似文献
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对比中国与土耳其抗震设计规范钢结构的适用范围、钢材强度等级限值和冲击韧性要求,中抗规对钢结构细化区别规定,土抗规钢结构适用面广;中抗规要求的钢材强度等级低于于土抗规,中抗规对钢材冲击韧性的要求高于土抗规.介绍中、土抗规钢板材宽厚比限值,以工字形截面钢框架梁为例,对比分析两抗规差别,得到梁轴压比较小时,两抗规翼缘宽度、腹... 相似文献
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Shreesha Rao D.S Mikkel Jensen Lars Grüner-Nielsen Jesper Toft Olsen Peter Heiduschka Bj?rn Kemper Jürgen Schnekenburger Martin Glud Mette Mogensen Niels M?ller Israelsen Ole Bang 《光:科学与应用(英文版)》2021,10(7):1372-1384
We present the first demonstration of shot-noise limited supercontinuum-based spectral domain optical coherence tomography (SD-OCT) with an axial resolution of ... 相似文献
29.
Won Kim Sang-Hyuk Lee Jung-Hwan Bang Hyun-Seok Uhm Jin-Seok Park 《Thin solid films》2011,520(5):1475-1478
In this study, a simple method of fabricating a thin-film transistor (TFT) with a double-layered channel using indium–zinc-oxide (IZO) films was proposed. Two IZO films used as channel layers were consecutively deposited via sputtering without stopping the vacuum and only by changing the volumetric fraction of the additive O2 gas during the deposition. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis showed a large difference in the depth profiles of the InO? and InO2? ions between the two IZO layers. Compared to the conventional single-IZO-channel TFT, the double-IZO-channel TFT that was fabricated using the proposed two-step deposition method showed greatly improved electrical characteristics: the on/off-state current ratio was increased from 1.30 × 105 to 1.03 × 106, and the field effect mobility was enhanced from 1.2 to 9.3 cm2/Vs. 相似文献
30.
The effect of compression on the crystallization behavior and corrosion resistance of Al(86)Ni9La5 amorphous ribbons was investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning elec-tron microscopy (SEM) and electrochemistry test. The XRD and TEM results reveal that the compressed Al(86)Ni9La5 ribbons spun with the circumferential speed (R) of 29.3 m/s are in fully amorphous state; however, the compressed ribbons spun with R=14.7 m/s have crystalline phases embedded in the amorphous matrix. The SEM images indicate that after compression, the toughness of the ribbons increases. Electrochemical results show that the compression decreases the stability of the passive film of the Al(86)Ni9La5 amorphous ribbons, because of the compression-introduced free volume, shear bands and crystalline phases; meanwhile, with R=14.7 m/s, the compression-induced crystalline phases in the Al(86)Ni9La5 ribbons increase the corrosion potential. 相似文献