排序方式: 共有28条查询结果,搜索用时 31 毫秒
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利用原子力显微镜技术(AFM),系统地研究了由乙醇与多价离子(hexammine cobalt(Ⅲ)[Co(NH3)36+])协同作用导致的λ-DNA凝聚现象.单独测得3价Co(NH3)36+的临界凝聚浓度大约是10μmol·L-1,乙醇的临界凝聚体积分数大约是15%.若3价离子[Co(NH3)36+]的浓度大于400μmol·L-1时,可以观察到DNA的解凝聚现象.在DNA溶液中同时加入乙醇(体积分数12%)与Co(NH3)36+(8μmol.L-1),当其浓度各低于其临界值,也可观察到凝聚现象,说明乙醇与Co(NH3)36+对DNA的凝聚有协同作用,而且在协同作用下,可以观察到典型的圆环结构(toroids).利用电荷逆转与离子释放机制分析了观察到的解凝聚现象. 相似文献
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抗生物素蛋白(avidin)在生物单分子实验中被广泛用于DNA与修饰表面的连接,同时avidin也可作为一种DNA载体用于基因治疗中.本文利用原子力显微镜(AFM)、动态光散射(DLS)、单分子磁镊(MT)技术系统地研究了avidin与DNA之间的相互作用,以及avidin引起DNA凝聚的机理.首先通过AFM对avidin-DNA复合体形貌进行观察,发现不但有avidin导致DNA凝聚的环状形貌,同时也存在avidin自身聚集引起的DNA凝聚现象,通过定量分析,发现其凝聚尺寸越来越小,而当avidin浓度大于2 ng·μL~(-1)时,其凝聚尺寸又突然变大.DLS实验结果也显示了同样的规律,伴随着avidin浓度的升高,DNA的粒径大小从大约170 nm减小到125 nm左右,其电泳迁移率由-2.76(10~(-4)cm~2·V~(-1)·s~(-1))变化到-0.1(10~(-4)cm~2·V~(-1)·~(-1)).此外,通过MT技术的力谱曲线变化,发现avidin导致的DNA凝聚与其他多价离子相比,长度的变化曲线几乎呈线性变化,偶尔存在少而小的阶跃,这种变化趋势与组蛋白的变化曲线更相似.因此可以判断,avidin导致DNA凝聚是由avidin与DNA的静电吸引和avidin自身聚集两种相互作用引起的. 相似文献
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The Ryderberg electronic wave packet dynamics of hydrogen atom near helium surface in an electric field is investigated using the semiclassical method.The autocorrelation function is calculated when the photoionized electron is excited by a short laser pulse for different atom-surface separations.The results show that new recurrences appear because of the helium surface,and the number of recurrent peaks increases with the decrease in atom-surface distance.The new feature is ascribed to the bifurcation of new closed orbits in the classical dynamics of the photoionized electron.Therefore,surface properties have a significant effect on the spectrum of nearby atoms or ions. 相似文献
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通过动态光散射技术与原子力显微镜观察了Co(NH3)63+导致的λ-DNA凝聚.用动态光散射测量溶液中Co(NH3)63+作用后的DNA粒径大小,结果表明凝聚后的粒径与样品培育时间和Co(NH3)63+的浓度有关,随着培育时间或者Co(NH3)36+浓度的增加,凝聚后的粒径都会慢慢变小,最后趋于稳定.粒径的分析采用单峰的分布模式处理,表明所有DNA由松散构象向凝聚构象转化的过程基本趋于一致.用原子力显微镜观察Co(NH3)63+导致DNA凝聚的形态变化,并进一步证明了凝聚粒径的单峰分布模式. 相似文献
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本文利用q变形振子模型,导出了双原子分子的势阱总能级数和离解能公式。实际计算表明,q振子模型计算的离解能,略大于实验值,误差平均约为10%,优于常用的Birge-Sponer外推法,可作为一种估算离解能的新方法。
关键词: 相似文献
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建立了一个以q振子为光场模型的光与物质相互作用的非线性理论,求得了薛定谔方程的形式解,并用微扰法求出一级近似的发射概率和吸收概率,同时求解了共振条件的拉比问题。在q→1时,恢复为普通线性理论。
关键词: 相似文献
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This paper studies the quantum dynamics of electrons in a surface
quantum well in the time domain with autocorrelation of wave packet.
The evolution of the wave packet for different manifold eigenstates with
finite and infinite lifetimes is investigated analytically. It is
found that the quantum coherence and evolution of the surface electronic
wave packet can be controlled by the laser central energy and
electric field. The results show that the finite lifetime of excited
states expedites the dephasing of the coherent electronic wave
packet significantly. The correspondence between classical and
quantum mechanics is shown explicitly in the system. 相似文献
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The autocorrelation function of electronic wave packet of hydrogen atom in a strong electric field below the zero-field ionization threshold is investigated in the formalism of semiclassical theory. It is found that the autocorrelation depends on the applied laser pulse significantly. In the case of narrow laser pulse, the reviving peaks in the autocorrelation can be attributed to the closed orbits of electrons, which are related to the classical dynamics of the system. But this correspondence is wiped out with increasing the laser width because of the interference among the adjacent reviving peaks. 相似文献