高性能聚焦离子束(FIB)系统及其在材料科学领域的应用     

周伟敏  吴国英 《实验室研究与探索》2004,23(9):19-20,52

采用液态镓作为离子源的FIB系统在材料科学研究领域可以起非常重要的作用。离子束聚焦于样品表面，在不同大小、束流及通入不同辅助气体的情况下，可分别实现图形刻蚀、绝缘和金属膜的沉淀，扫描离子成像等功能。该系统有三大用途：形貌观察，分辨率高达5nm；微刻蚀以及微沉淀。本文介绍了FIB技术的应用。  相似文献   

Effects of light curing modes and ethanol-wet bonding on dentin bonding properties     

Mu-zi Li  Jin-rui Wang  Hong Liu  Xia Wang  Kang Gan  Xiu-ju Liu  De-li Niu  Xiao-qing Song 《Journal of Zhejiang University. Science. B》2016,17(9):703-711

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Another Nail in the Coffin for Learning Styles? Disparities among Undergraduate Anatomy Students’ Study Strategies,Class Performance,and Reported VARK Learning Styles     

Polly R. Husmann  Valerie Dean O'Loughlin 《Anatomical sciences education》2019,12(1):6-19

The concept and existence of learning styles has been fraught with controversy, and recent studies have thrown their existence into doubt. Yet, many students still hold to the conventional wisdom that learning styles are legitimate, and may adapt their outside of class study strategies to match these learning styles. Thus, this study aims to assess if undergraduate anatomy students are more likely to utilize study strategies that align with their hypothetical learning styles (using the VARK analysis from Fleming and Mills, 1992 , Improve Acad. 11:137–155) and, if so, does this alignment correlate with their outcome in an anatomy course. Relatedly, this study examines whether students’ VARK learning styles are correlated with course outcomes regardless of the students’ study strategies, and whether any study strategies are correlated with course outcomes, regardless of student-specific VARK results. A total of 426 anatomy students from the 2015 and 2016 Fall semesters completed a study strategies survey and an online VARK questionnaire. Results demonstrated that most students did not report study strategies that correlated with their VARK assessment, and that student performance in anatomy was not correlated with their score in any VARK categories. Rather, some specific study strategies (irrespective of VARK results), such as use of the virtual microscope, were found to be positively correlated with final class grade. However, the alignment of these study strategies with VARK results had no correlation with anatomy course outcomes. Thus, this research provides further evidence that the conventional wisdom about learning styles should be rejected by educators and students alike. Anat Sci Educ. © 2018 American Association of Anatomists.  相似文献   

AMS radiocarbon dating and scientific examination of high historical value manuscripts: Application to two Chinese manuscripts from Dunhuang     

Pascale Richardin  Franoise Cuisance  Nathalie Buisson  Victoria Asensi-Amoros  Catherine Lavier 《Journal of Cultural Heritage》2010,11(4):176-403

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Two-dimensional characterization of three-dimensional magnetic bubbles in Fe3Sn2 nanostructures     

Jin Tang  Yaodong Wu  Lingyao Kong  Weiwei Wang  Yutao Chen  Yihao Wang  Y Soh  Yimin Xiong  Mingliang Tian  Haifeng Du 《国家科学评论(英文版)》2021,8(6)

We report differential phase contrast scanning transmission electron microscopy (TEM) of nanoscale magnetic objects in Kagome ferromagnet Fe₃Sn₂ nanostructures. This technique can directly detect the deflection angle of a focused electron beam, thus allowing clear identification of the real magnetic structures of two magnetic objects including three-ring and complex arch-shaped vortices in Fe₃Sn₂ by Lorentz-TEM imaging. Numerical calculations based on real material-specific parameters well reproduced the experimental results, showing that the magnetic objects can be attributed to integral magnetizations of two types of complex three-dimensional (3D) magnetic bubbles with depth-modulated spin twisting. Magnetic configurations obtained using the high-resolution TEM are generally considered as two-dimensional (2D) magnetic objects previously. Our results imply the importance of the integral magnetizations of underestimated 3D magnetic structures in 2D TEM magnetic characterizations.  相似文献   

有机分子组装体系的扫描隧道显微镜研究     

裘晓辉  白春礼 《中国科学院大学学报》2003,20(1):107-111

利用长链烷烃取代基与石墨表面的较强相互作用,可以获得烷基取代的有机小分子(酞菁、卟啉、碱基)的高分辨STM图像.理论分析表明,这些分子的吸附稳定性来源于长链烷基与石墨间较强的范德华相互作用,以及长链烷烃链间的二维结晶能.分子在表面的吸附组装结构受到分子与基底间、吸附分子间,以及溶剂与分子间作用的共同影响.对于长链烷基取代的碱基分子在石墨表面的组装结构中,分子的排列方式不仅受到烷基链与石墨间较强的取向匹配的作用,碱基分子间形成的多个氢键以及芳环离域π键的作用也会影响分子的排列方式,并且是造成烷基取代碱基分子组装结构多样性的原因.扫描隧道谱研究表明,硫醇在Au表面的自组装分子膜对电流的整流作用,来自于分子中巯基与Au表面形成的双电层,而不对称取代的NtBuPc分子在石墨表面的LB膜的电流整流行为,来源于分子内部的不对称电子结构.  相似文献   

力竭运动大鼠心肌心钠素表达的变化   总被引：40，自引：4，他引：36  

潘珊珊  张炎  陆爱云  姜宗来  杨向群 《体育科学》2000,20(3):66-69

为了探讨力竭运动对大鼠心脏心钠素表达的影响,采用４月龄雄性ＸＤ大鼠,体重２２０ｇ－３６０ｇ,随机分为（１）正常对照组（Ａ组）,（２）有训练游泳力竭组（Ｂ组）、（３）无训练游力竭组（Ｃ组）,每组各１４只。灌注后取出整心,用免疫组化ＡＢＣ法,结果是：心钠素免疫阳性反应为：右心耳〉右心房〉左心房〉右心室近心房处,与Ａ组相比,Ｂ组大鼠心房肌心钠素阳性择应明显增强,心钠素电子致密颗粒大量增加;Ｃ组大鼠心房钠  相似文献   

针刺和静力牵张对大负荷运动后人骨骼肌Z带变化影响的免疫电镜研究     

李晓楠  樊景禹  卢鼎厚 《体育科学》1992,(6)

我们用兔抗人α-actinin(α-辅肌动蛋白)抗血清和羊抗兔IgG-胶体金复合物作为标记物,在由Lowicryl K4M包埋的组织超薄切片上定位Z带蛋白α-actinin。在大负荷斜蹲后48小时从6名男性受试者(年龄为22—22岁)的两侧腿股外肌中取得活检样品,并在运动后不同时刻及活检取样前对随机确定的每一受试者的一条腿进行针刺或静力牵张,另一侧腿作对照。结果发现,针刺或静力牵张腿Z带特异性标记密度比其对照腿高。此外,针刺或静力牵张还能使Z带发生超微结果的变化率分别减少36％和22％,并使显著变化的比例减少,轻度变化的比例增加。以上观察结果揭示了针刺或静力牵张能抑制由于α-actinin的解聚或降解引起的Z带超微结构变化过程,或者通过加速α-actinin的聚合或合成而促进Z带超微结构的恢复。  相似文献   

Atomic origin of spin-valve magnetoresistance at the SrRuO3 grain boundary     

Xujing Li  Li Yin  Zhengxun Lai  Mei Wu  Yu Sheng  Lei Zhang  Yuanwei Sun  Shulin Chen  Xiaomei Li  Jingmin Zhang  Yuehui Li  Kaihui Liu  Kaiyou Wang  Dapeng Yu  Xuedong Bai  Wenbo Mi  Peng Gao 《国家科学评论(英文版)》2020,7(4):755

Defects exist ubiquitously in crystal materials, and usually exhibit a very different nature from the bulk matrix. Hence, their presence can have significant impacts on the properties of devices. Although it is well accepted that the properties of defects are determined by their unique atomic environments, the precise knowledge of such relationships is far from clear for most oxides because of the complexity of defects and difficulties in characterization. Here, we fabricate a 36.8° SrRuO₃ grain boundary of which the transport measurements show a spin-valve magnetoresistance. We identify its atomic arrangement, including oxygen, using scanning transmission electron microscopy and spectroscopy. Based on the as-obtained atomic structure, the density functional theory calculations suggest that the spin-valve magnetoresistance occurs because of dramatically reduced magnetic moments at the boundary. The ability to manipulate magnetic properties at the nanometer scale via defect control allows new strategies to design magnetic/electronic devices with low-dimensional magnetic order.  相似文献   

Anti-seismic behavior of HRB400 reinforced steel bars   总被引：1，自引：0，他引：1  

秦斌 《重庆大学学报(英文版)》2005,4(1):23-27

1 Introduction Steel bar is one of the most important constructional materials ensuring the safety of buildings, and sufficient anti-seismic strength is required when it is applied to buildings in the region where an earthquake might occur. HRB335 steel bars are being used in China while 400 MPa steel bars are wildly used in Europe [1]. To ensure the security of buildings, 400 MPa steel bars have been developed in China. Before these steel bars being wildly used, a full-scale survey of the…  相似文献