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Individual DNA molecules were first stretched by a centrifugal force and adsorbed on a modified mica surface.Then,a liquid flow was guided across the surface along a direction perpendicular to the aligned DNA strands.Some nano-catenary-like patterns of DNA molecules were formed,which were revealed by atomic force microscopy.A physical mechanism called the “s-suspension bridge” model has been presented,by which the features of the catenary-like patterns of DNA molecules can be understood quantitatively quite well. 相似文献
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分析了空间超光谱成像仪前置光学系统的热光学特性。应用有限元方法建立了模拟前置光学系统的热弹性变形模型,并进行了热弹性分析计算;用Zernike多项式拟合分析结果,求得各镜子反射面在热变形后的面型误差和相对于初始理想位置的偏移;利用光学分析设计软件Code V计算得到光学系统的像面与焦面的偏离量,即离焦量,并用多项式拟合得到其随温度变化的规律。计算结果表明,前置光学系统的像面在温度改变时会偏离焦面,离焦量与温度近似地成线性关系,当温度升高时像面最大偏移量为107.4μm,温度降低时像面最大偏移量为106.9μm。该分析结果可作为指导超光谱成像仪改进热控措施,进行调焦补偿的理论参考。 相似文献
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信息系统安全风险的属性评估方法 总被引:5,自引:2,他引:3
首次将属性理论和属性综合评估模型引入信息系统安全风险的评估领域 ,为信息系统安全风险程度的评估提出了一种新方法 ,对于信息系统安全性的动态管理有着积极的意义 . 相似文献
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A transferable tight-binding potential for nickel together with molecular-dyna mics methods and simulated-annealing techniques have been used to study the str uctures and structural properties of nickel clusters.We have obtained the struct ures and their
关键词: 相似文献
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The performance of space hyper spectral imager is severely affected by turbulent orbit temperature. Tur-bulence results in a defocus in the fore optical system of the imager. To address this problem, a focusing system is added. A number of simulation methods are applied on the fore optical system to study the relationship between temperature and focusing. In addition, this process is conducted to obtain a practical reference for focusing while the imager is flying on orbit. The obtained correlation between focusing and temperature is proven effective based on ground imaging and simulation testing. 相似文献
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光斑强度对光电位敏探测器测量准确度的影响 总被引:1,自引:0,他引:1
根据位敏探测器的理想定位模型及其信号处理方式,建立了位敏探测器位移测量误差的数学模型,以获得高准确度的位移测量.所建模型显示系统的测量误差随光斑强度增大而减小,随电噪音增大而增大.为了验证理论模型的正确性,以单颗红外发光二级管作为靶标光源,用枕型位敏探测器及其测试电路板在暗室中搭建了实验系统,分别在9组不同光斑强度下对21个位置点进行位移测量实验,相邻两位置点的间距为0.3mm.使用MATLAB的CFTOOL工具对每组测得位移值进行拟合,以均方根误差作为准确度的评价指标,结果表明:位移实验的准确度值与模型计算的准确度值基本符合,准确度随光斑强度变化的趋势完全一致. 相似文献
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We investigate the unified first law and the generalized second law in a modified holographic dark energy model. The thermodynamical analysis on the apparent horizon can work and the corresponding entropy formula is extracted from the systematic algorithm. The entropy correction term depends on the extra-dimension number of the brane as expected, but the interplay between the correction term and the extra dimensions is more complicated. With the unified first law of thermodynamics well-founded, the generalized second law of thermodynamics is discussed and it is found that the second law can be violated in certain circumstances. Particularly, if the number of the extra dimensions is larger than one, the generalized law of thermodynamics is always satisfied; otherwise, the validity of the second law can only be guaranteed with the Hubble radius greatly smaller than the crossover scale rcof the 5-dimensional DGP model. 相似文献
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首先用液流拉伸单分子DNA,使其吸附在修饰过的云母基片上.然后让二次液流沿着垂直于已拉伸的DNA的方向流过云母片,用原子力显微镜(AFM)观测,可见DNA单分子片段在基片上形成了一些纳米尺度的悬链线.提出一种“S悬桥”模型能定量地解释这一现象.该研究工作揭示,在DNA的单分子操作中,经典的弹性力学理论足以描述和控制DNA分子二维图形的形成
关键词:
DNA
单分子DNA操纵
原子力显微镜(AFM)
纳米悬链线 相似文献