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Computing methods for icosahedral and symmetry-mismatch reconstruction of viruses by cryo-electron microscopy
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Three-dimensional(3 D) reconstruction of icosahedral viruses has played a crucial role in the development of cryoelectron microscopy single-particle reconstruction, with many cryo-electron microscopy techniques first established for structural studies of icosahedral viruses, owing to their high symmetry and large mass. This review summarizes the computational methods for icosahedral and symmetry-mismatch reconstruction of viruses, as well as the likely challenges and bottlenecks in virus reconstruction, such as symmetry mismatch reconstruction, contrast transformation function(CTF)correction, and particle distortion. 相似文献
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本文用数论分析方法,给出有重位点阵关系两相空间点阵及其点阵平面重合系数求法的普遍而简便的公式。空间点阵的重合系数α2(3)=1/|C(1)|,点阵平面的重合系数α2(h)= (H(2)C(1)/|C(1)|, C(1)为重位点阵基矢对应矩阵,H(2)=[h1(2)h2(2)h3(2)].在C(1)未知的情况下,空间点阵及其点阵平面的重合系数可以通过两相基矢有理对应矩阵φ及重合系数矩阵C来求,这时α2(3)= k1(2)k2(2)/d3, α2(h)=(CH(2),dk1(2))/d2.求矩阵C比求矩阵C(1)要方便得多。
关键词: 相似文献
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观察了面心立方镍基合金中重叠微孪晶界面的各种条纹象,发现它们与α条纹及σ条纹不同,当改变基体或孪晶偏离参量的正负号时,重叠区域条纹的衬度会发生明显的改变,本文将多束动力学衍射理论的叠代法用于重叠孪晶界面几种条纹强度的模拟计算,计算束数包括基体、孪晶及其二次衍射在内共九束,计算的强度曲线与实验强度曲线符合良好,分析结果指出,重叠孪晶界面条纹衬度的明显变化是异常吸收或异常透射效应及基体-孪晶-基体三层晶体多束动力学交互作用的结果。
关键词: 相似文献
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A completely different formulation for simulation of the high order Laue zone (HOLZ) diffractions is derived. It refers to the new method, i.e. the Taylor series (TS) method. To check the validity and accuracy of the TS method, we take polyvinglidene fluoride (PVDF) crystal as an example to calculate the exit wavefunction by the conventional multi-slice (CMS) method and the TS method. The calculated results show that the TS method is much more accurate than the CMS method and is independent of the slice thicknesses. Moreover, the pure first order Lane zone wavefunction by the TS method can reflect the major potential distribution of the first reciprocal plane. 相似文献
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本文用矩阵及数论分析方法给出了重位点阵的两种新的解法。在此基础上对相重阵点判别式进行归并,使有重位点阵关系两相复合点阵问题的处理大为简化。证明了整个立方晶系的自重合问题,绝大多数非立方晶系的自重合问题以及一部分互重合问题,都可以通过判别式的归并得以简化。 相似文献
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制备了一种新型掺Er3 锗铋酸盐玻璃。分析了吸收光谱和上转换荧光光谱,并应用Judd-Ofelt理论计算了锗铋酸盐玻璃的3个强度参量tΩ(t=2,4,6),分别为Ω2=3.35×10-20cm2,Ω4=1.34×10-20cm2以及Ω6=0.67×10-20cm2。研究了在两种不同的激发光下(980和808 nm)锗铋酸盐玻璃的发光机制。根据McCumber理论,分析了在1.55μm光通讯窗口的光谱性质,计算了能级4I13/2→4I15/2跃迁的受激发射截面,结果显示掺Er3 锗铋酸盐玻璃具有较宽的荧光半高宽和较大的受激发射截面。因此有希望成为高效的上转换发光材料和1.55μm光通讯材料。 相似文献