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1.
本文通过比较细菌叶绿素a(BChl a)吸附于Au纳米颗粒表面前后吸收光谱、荧光光谱、绝对量子产率和荧光寿命的变化,研究金纳米颗粒表面对吸附态细菌叶绿素a(BChl a)自发荧光辐射过程的影响。结果表明,BChl a吸附到Au纳米颗粒表面后,单体和二聚体BChl a吸收峰位均红移约3nm;BChl a单体发射的荧光峰位置从784nm红移到791nm,BChl a二聚体发射的荧光峰位置从684nm红移到689nm,二者荧光均发生淬灭;荧光量子效率降低;荧光寿命在误差范围内保持不变。原因可能来自两个方面:(1)BChl a吸附到Au导电表面后使得与自发辐射跃迁速率相关的光子能态密度变小,从而使BChl a自发辐射速率降低;(2)BChl a与纳米Au颗粒表面间的无辐射能量转移导致吸附态BChl a非辐射速率增大。  相似文献
2.
光学分子成像技术观察纳流芯片对DNA分子的研究   总被引:2,自引:2,他引:0       下载免费PDF全文
λ-DNA与荧光染料YOYO-1结合,利用荧光显微技术对DNA分子在毛细现象作用下进入宽40 nm、深60 nm的纳米沟道内,并在其内部被拉伸以及沿沟道移动的情形进行了观察.讨论了DNA分子在沟道内的运动情况.结合光学分子成像技术与该尺寸范围的纳流芯片,将有助于研究生物分子的动力学和静力学性质.  相似文献
3.
赵慧  殷雄  李恒  林原  翁羽翔 《中国物理快报》2007,24(11):3272-3275
Time-resolved mid-IR transient absorption spectroscopy is employed to explore the mechanism of improving the performance of dye-sensitized TiO2 solar cell (DSSC) when a certain amount of H2 0 is added into the electrolyte. The relaxation kinetics of dye-sensitized TiO2 nanocrystalline film and the corresponding DSSC performance are investigated under different conditions. It is found that the interracial charge recombination is retarded and electron injection efficiency is increased in the water vapour and in the electrolyte when D20 is added. The values of open-circuit photovoltage Voc and the short-circuit photocarrent Jsc of the cells are linearly correlated to the product of the two decay time constants. We also observed that Voc well correlates with electron injection efficiency. It provides a preliminary microscopic account for the function of the added water in improving the performance of DSSCs.  相似文献
4.
李伟  窦硕星  王鹏业 《物理》2005,34(12):877-882
在真核生物中,DNA按左手手征性的方式,缠绕在组蛋白八聚体的周围,形成稳定的核小体结构.文章作者运用布朗动力学,数值模拟了DNA与组蛋白相互作用最终形成核小体的动力学过程,揭示了DNA与组蛋白相互作用的详细图景,并提出了组蛋白八聚体旋转模型,以解释这一过程.文章作者还计算了组成核小体的DNA在受到拉伸力时,组蛋白被从核小体中剥离下来的动力学过程,得到了组装和剥离过程的详细图像,给出了与前人单分子实验一致的拉伸力与拉伸长度的关系曲线和拉伸台阶.此外,还通过建立的组蛋白手征性模型,模拟了核小体手征性的形成过程,发现DNA的缠绕方向强烈依赖于组蛋白的手征性,显示出环境温度对核小体手征性有重要影响.  相似文献
5.
储谦谨  尹华伟  翁羽翔 《中国物理》2007,16(10):3052-3058
The coherent exciton plays an important role in the photosynthetic primary process, and its functions are deeply dependent on the orientation arrangements of local transition dipole moments (TDMs). We theoretically and systematically study the physical property of the coherent exciton at different orientation arrangements of the local TDMs in circular light-harvesting (LH) complexes. Especially, if the orientation arrangements are different, the delocalized TDMs of the coherent excitons and the energy locations of the optically active coherent excitons (OACEs) can be obviously different, and then there are more manners to capture, store and transfer light energy in and between LH complexes. Similarly, if the orientation arrangements are altered, light absorption and radiative intensities can be converted fully between the OACEs in the upper and lower coherent exciton bands, and then the blue and red shifts of the absorption and radiative bands of the pigment molecules can occur simultaneously at some orientation arrangements. If the systems are in the vicinities of the critical orientation arrangements, the weak static disorder or small thermal excitation can destroy the coherent electronic excitations, and then the coherent exciton cannot exist any more.  相似文献
6.
谢平  窦硕星  王鹏业 《中国物理》2006,15(3):536-541
A fluctuating ratchet model of non-Markov process is presented to describe the processive movement of molecular motors of single-headed kinesin KIF1A,where the fluctuation perturbation to the local potential is introduced and the detailed ATPase pathway of the motor is included. The theoretical results show good quantitative agreement with the previous experimental ones.  相似文献
7.
谢平  窦硕星  王鹏业 《中国物理》2005,14(4):744-752
Myosin V and myosin VI are two classes of two-headed molecular motors of the myosin superfamily that move processively along helical actin filaments in opposite directions. Here we present a hand-over-hand model for their processive movements. In the model, the moving direction of a dimeric molecular motor is automatically determined by the relative orientation between its two heads at free state and its head‘s binding orientation on track filament.This determines that myosin V moves toward the barbed end and myosin VI moves toward the pointed end of actin.During the moving period in one step, one head remains bound to actin for myosin V whereas two heads are detached for myosin VI: the moving manner is determined by the length of neck domain. This naturally explains the similar dynamic behaviours but opposite moving directions of myosin VI and mutant myosin V (the neck of which is truncated to only one-sixth of the native length). Because of different moving manners, myosin VI and mutant myosin V exhibit significantly broader step-size distribution than native myosin V. However, all the three motors give the same mean step size of -36nm (the pseudo-repeat of actin helix). All these theoretical results are in agreement with previous experimental ones.  相似文献
8.
谢平  窦硕星  王鹏业 《中国物理》2005,14(4):734-743
驱动蛋白马达在实验和理论上已被进行了广泛的研究. 然而, 其行进运动的微观机理仍未确定. 在本文中我们基于化学、力学和电学耦合提出了一个交臂模型来描述这种行进运动. 在该模型中,驱动蛋白两个头的ATP水解化学反应速率由作用在其颈上的力(包括内部弹性力和外部负荷)来调控. 在低外部负荷情况下, 驱动蛋白的后头的ATP水解化学反应速率远大于前头的速率, 因而两个头在ATP水解化学反应和力学周期循环中是协调的且马达以每步消耗一个ATP的方式的行走. 在大的前向负荷情况下, 两个头的ATP水解化学反应速率变得可比拟, 因而两个头在ATP水解化学反应和力学周期循环中不再很好地协调. 该模型与驱动蛋白的结构研究结果以及ATP水解化学反应路径一致. 利用此模型所估算的驱动力(约5.8 pN)与实验结果(5~7.5 pN)一致. 所估算的每步中的运动时间(约10)也与实验测量值(0~50)符合. 解释了已观察到的每步(8nm)分为两个半步的现象. 所得到的运动速度-负荷曲线与已有的实验结果一致.  相似文献
9.
钱钧  谢平  窦硕星  王鹏业 《中国物理》2005,14(11):2214-2221
ATP synthase is a rotary motor which is composed of two portions: the ‘rotor' Fo, consisting of a c-ring, and the ‘stator' F1, consisting of an a3/33 hexamer. In different species, the number of c-subunits which form the c-ring is varied from 10 to 14, whereas the a3/33 hexamer is fixed to be 3-fold symmetrical. We have numerically studied the rotational coupling between Fo with varied number of c-subunits and F1. It is found that, for any number of c-subunits, the rotor Fo advances 3 steps per revolution on average, which is determined by the period of F1, whereas the exact angular pausing positions are determined by the period of Fo. When the symmetry of the c-ring of Fo is matched with the 3-fold symmetry of F1, the three steps have equivalent sizes. If not matched, the three steps become nonequivalent: both the step size and average dwell time are different for these steps.  相似文献
10.
Elucidating the initial kinetics of folding pathways is critical to the understanding of the protein folding mechanism. Transient infrared spectroscopy has proved a powerful tool to probe the folding kinetics. Herein we report the construction of a nanosecond laser-induced temperature-jump (T-jump) technique coupled to a nanosecond timeresolved transient mid-infrared (mid-IR) spectrometer system capable of investigating the protein folding kinetics with a temporal resolution of 50 ns after deconvolution of the instrumental response function. The mid-IR source is a liquid N2 cooled CO laser covering a spectral range of 5.0μm (2000 cm^-1)-6.5μm (1540 cm^-1). The heating pulse was generated by a high pressure H2 Raman shifter at wavelength of 1.9μm. The maximum temperature-jump could reach as high as 26±1℃. The fast folding/unfolding dynamics of cytochrome C was investigated by the constructed system, providing an example.  相似文献
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