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排序方式: 共有1112条查询结果,搜索用时 15 毫秒
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四种别藻蓝蛋白三聚体的时间分辨荧光光谱研究 总被引:6,自引:0,他引:6
研究了从Anabanavaribilis中提取的4种别藻蓝蛋白APCI,APCII,APCII及APCB三聚体的稳态光谱和皮秒荧光光谱。采用Monte-Carlo方法对瞬态荧光光谱进行拟合,实验结果表明:APCI荧光有两个带,其中第一个带位于662nm,有两个时间组分:35.8ps和1.67ns;第二个带位于680nm,有两个时间组分:34.2ps和1.64ns;APCII瞬态荧光位于660nm,有两个时间组分:20.4ps和1.64ns;APCII瞬态荧光位于660nm,有两个时间组分:23.8ps和1.76ns;APCB瞬态荧光有两个带,其中第一个带位于662nm,有两个时间组分:36.6ps和1.45ns;第二个带位于680nm,有两个时间组分:25.8ps和1.62ns。实验结果一方面说明了藻胆体核内4种别藻蓝蛋白形成能量传递的两条途径;另一方面瞬态荧光解叠结果揭示了APCI和APCB三聚体内能量传递的超快过程。 相似文献
3.
双原子系统中原子非经典特性与光场非经典特性的关联 总被引:2,自引:0,他引:2
本文研究了双原子与双模光场相互作用系统中,双原子分崩离析有压缩与双模光场二阶压缩间的对称关系。揭示了原子间关系和光场模间关联的转换特性,并探讨了失谐量,耦和常数对原子非经典特性与光场非经典特性间关联的影响。 相似文献
4.
Electric dipoles radiate an electromagnetic field into their surroundings. The electric and magnetic fields from a point source or from linear dipoles have components parallel to a spherical surface but also a radial component. In most investigations on radiated fields, only the part of the electric field that is parallel to a spherical surface is taken into account. The argument is that only that component contributes to the radiated energy. Here we show that the phase front in the lower half space is not a spherical surface and hence, the radial components contribute to radiated energy. We show differences in radiation patterns for point electric dipoles and linear dipoles, either modeled as perfectly conducting wires or as resistively loaded wires. Our primary interest lies with improving image resolution through processing of Ground-Penetrating Radar data. Here the emphasis lies with understanding the radiation characteristics of linear dipoles that can be incorporated with image processing algorithms. The model uses a thin-wire approximation for the transmitter antenna. The solution to the discrete system of equations is solved, incorporating interaction between the interface, using a CGFFT scheme including symmetrization and a newly developed preconditioning operator. We look at the electric and magnetic fields as well as the time-averaged Poynting vector radiation patterns in the E-plane and H-plane of the transmitting antenna. The results show that the radial component of the radiated electric and magnetic field is not negligible, even at distances more than seven wavelengths away from the antennas. 相似文献
5.
在风洞中用电子扫描阀进行测压实验,研究了底部间隙和锯齿高度对扰流片引起的壁面压力分布的影响。结果表明底部间隙在g/h≥1.0时对扰流片上游壁面压力分布曲线有较大影响,而对下游回流区压力分布曲线的影响主要在0≤g/h≤2.0的区域内;并且在g/^=0.2、1.0时,流动结构发生改变。另外,锯齿扰流片的当量面积与平板扰流片相等时,锯齿高度对下游底板压力分布特性的影响亦主要限于0≤x/h≤2.0的区域。 相似文献
6.
7.
Vibrational mode in a two-dimensional dust monolayer is investigated by considering the finite size of dust grains. Each dust grain is assumed to be a negative point charge and a dipole moment due to the inhomogeneous charge distribution on its surface. The dispersion relation of the vibrational mode is derived. Both the self-excited and externally excited cases are discussed. It is shown that the mode is sensitive to the direction of the dipole moment. 相似文献
8.
Reinhold Ludwig Sergey Makarov Diran Apelian 《Journal of Nondestructive Evaluation》1998,17(3):153-166
This paper investigates electrostatic voltage distributions around a surface-breaking flaw due to an injected current of known
strength. The direct 3-D solution of the voltage behavior over the flawed surface is obtained numerically by the use of a
boundary integral formulation. A novel iteration method is applied to solve the resulting electrostatic integral equation
for the unknown surface voltage distribution. In addition to investigating the sensitivity of different flaw sizes to the
observed surface voltage distribution, important issues such as suitable probe spacing and current flow orientation are studied.
For sufficiently small surface-breaking flaws, a simple image source model is developed to evaluate the voltage response of
hairline cracks. The model is tested by comparing it with the developed numerical solution. Experiments aimed at establishing
the validity of the modeling approach show remarkable agreement with the theoretical model. 相似文献
9.
Aleksandra A. Ageeva Ilya M. Magin Alexander B. Doktorov Victor F. Plyusnin Polina S. Kuznetsova Alexander A. Stepanov Alexander A. Alekseev Nikolay E. Polyakov Tatyana V. Leshina 《International journal of molecular sciences》2021,22(12)
The study of the L- and D-amino acid properties in proteins and peptides has attracted considerable attention in recent years, as the replacement of even one L-amino acid by its D-analogue due to aging of the body is resulted in a number of pathological conditions, including Alzheimer’s and Parkinson’s diseases. A recent trend is using short model systems to study the peculiarities of proteins with D-amino acids. In this report, the comparison of the excited states quenching of L- and D-tryptophan (Trp) in a model donor–acceptor dyad with (R)- and (S)-ketoprofen (KP-Trp) was carried out by photochemically induced dynamic nuclear polarization (CIDNP) and fluorescence spectroscopy. Quenching of the Trp excited states, which occurs via two mechanisms: prevailing resonance energy transfer (RET) and electron transfer (ET), indeed demonstrates some peculiarities for all three studied configurations of the dyad: (R,S)-, (S,R)-, and (S,S)-. Thus, the ET efficiency is identical for (S,R)- and (R,S)-enantiomers, while RET differs by 1.6 times. For (S,S)-, the CIDNP coefficient is almost an order of magnitude greater than for (R,S)- and (S,R)-. To understand the source of this difference, hyperpolarization of (S,S)-and (R,S)- has been calculated using theory involving the electron dipole–dipole interaction in the secular equation. 相似文献
10.
A method for evaluating the dipole moments of copolymers in relation to the distribution of polar unit sequences is proposed. Experimental data on the synthesis and dipole moments of styrene-p-chlorostyrene and styrene-p-methoxystyrene copolymers were used to calculate the effective dipole moment of a polar unit in a copolymer. For this purpose, we assumed the following effective moment values for the corresponding polar unit sequences along the copolymer chains: when both of the nearest neighbours are polar, μPP, when one of the nearest neighbours is polar and the other is non-polar, μPS, and when both of the nearest neighbours are non-polar, μSS. The relative magnitudes of μSS, μPS and μPP calculated for both copolymers reflect the influence of dipole-dipole interactions on the effective dipole moment of a polar unit in a copolymer molecule. 相似文献