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91.
92.
酒石酸乙酰异戊酰泰乐菌素(ATLL)是一种新的大环内酯类兽用抗菌药,研究 ATLL与蛋白质的相互作用非常重要,这直接与 ATLL 在体内的药效相关。牛血清白蛋白(BSA )结构上与人血清白蛋白(HSA)同源,因此,常用它作研究药物与蛋白质相互作用的蛋白模型。血液中有许多金属离子,已有关于体内单一离子对药物与蛋白质相互作用影响的研究,采用多光谱方法对ATLL与BSA相互作用及Zn2+和Cu2+的影响进行研究。结果表明,BSA的荧光猝灭属于静态猝灭,Zn2+和Cu2+分别使有效猝灭常数降低和增大。主要的相互作用力为氢键和疏水作用力。ATLL改变蛋白质色氨酸和酪氨酸的微环境极性。紫外光谱分析发现,Cu2+可能是通过Cu2+‐ATLL复合物以金属离子架桥作用来影响ATLL与BSA的作用,Zn2+可能通过与ATLL的竞争作用结合BSA。红外光谱分析表明,ATLL使BSA的β‐折叠和α‐螺旋结构向β‐转角和无规卷曲转变。这些基础数据有助于阐明在生理条件下,有无Zn2+,Cu2+时ATLL与BSA的相互作用机制及金属离子在药物与蛋白质作用过程中对蛋白质功能的影响。 相似文献
93.
Vladimír Slugeň Oleksandr Gokhman Stanislav Pecko Stanislav Sojak Frank Bergner 《辐射效应与固体损伤》2016,171(3-4):231-241
The paper is focused on a comprehensive study of JRQ and JPA reactor pressure vessel steels from the positron annihilation lifetime spectroscopy (PALS) point of view. Based on our more than 20 years’ experience with characterization of irradiated reactor steels, we confirmed that defects after irradiation start to grow and/or merge into bigger clusters. Experimental results shown that JPA steel is more sensitive to the creation of irradiation-induced defects than JRQ steel. It is most probably due to high copper content (0.29?wt.% in JPA) and copper precipitation has a major impact on neutron-induced defect creation at the beginning of the irradiation. Based on current PALS results, no large vacancy clusters were formed during irradiation, which could cause dangerous embrittlement concerning operation safety of nuclear power plant. The combined PALS, small angle neutron scattering and atomic probe tomography studies support the model for JRQ and JPA steels describing the structure of irradiation-induced clusters as agglomerations of vacancy clusters (consisting of 2–6 vacancies each) and are separated from each other by a distribution of atoms. 相似文献
94.
95.
F. Ames P. Schmidt O. Forstner G. Bollen O. Engels D. Habs G. Huber 《Hyperfine Interactions》2001,132(1-4):465-468
The beam quality of radioactive ion beams produced by present target ion source technology is often not sufficient for direct
post-acceleration. Furthermore, pulsed beams insure a more efficient use of an accelerator. In the case of REX-ISOLDE, the
post accelerator at the CERN ISOLDE facility, a gas-filled Penning trap (REXTRAP) has been chosen for accumulation of the
radioactive ions and conversion into cooled bunches. Radial centering of the ions is achieved by applying an rf field with
a frequency equal to the cyclotron frequency of the desired ion species. The efficiency achieved in the first tests with different
isotopes covering nearly the entire mass range was already >20%. Going to total numbers of >105 stored ions in the trap a shift of the centering frequency could be observed, which is most likely due to space charge effects.
Despite this, it was possible to accumulate up to 107 ions and deliver them as cooled bunches.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
96.
M. Dubiel S. Brunsch W. Seifert H. Hofmeister G.L. Tan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):229-232
Ag particles of 3.9 and 5.1 nm mean size in silicate glasses were produced by ion exchange and subsequent annealing at 480
and 600 °C. These thermal treatments may induce stresses in matrix and particles in addition to the well known effect of surface atoms
because of the thermal expansion mismatch of both materials. Structural characterisation of the particles by high-resolution
electron microscopy revealed a size-dependent lattice dilatation quite opposite to the so far observed lattice contraction
of similar metal/glass composites. This result, confirmed by X-ray absorption spectroscopy at the Ag K-edge, is discussed
in terms of an Ag-Ag bond length increase near the particle surface. The temperature-dependent EXAFS spectra (10-300 K) indicate
an increased thermal expansion coefficient of the particles with an increased mean particle size calculated on the basis of
an anharmonic Einstein model. With that the bond length increase can be explained. The results can be interpreted by a combination
of both the particle size effects and the influence of the surrounding matrix.
Received 30 November 2000 相似文献
97.
98.
Tuong Lan Nguyen Masayuki Dokiya Shaorong Wang Hiroaki Tagawa Takuya Hashimoto 《Solid State Ionics》2000,130(3-4):229-241
The electrical property of (La1−xSrx)1−z(Al1−yMgy)O3−δ (LSAM; x≤0.3, y≤0.15 and z≤0.1) was measured using the DC four-probe method as a function of temperature (500–1000°C) and oxygen partial pressure (1–10−22 atm). Among LSAMs, (La0.9Sr0.1)AlO3−δ showed the highest ionic conductivity, σi=1.3×10−2 S cm−1 at 900°C. A simultaneous substitution at A and B sites or A site deficiency is expected to create larger oxygen vacancy and higher ionic conductivity. However, it showed a negative effect. The effect of the vacancy increase did not effect monotonously the ionic conductivity. It was found that the concentration of oxygen vacancy, [VO], influences not only the oxide ion conductivity, σi, but also the mobility, μv, of [VO]. These properties exhibit a maximum at around [VO]=0.05. With the increase in [VO], the activation energy, Ea, of the ionic conduction dropped from 1.8 to ca. 1.0 eV at [VO]=0.05 and became almost constant at [VO]>0.05. The dependency of the pre-exponential term, μ0v, and Ea on [VO] was analyzed and their effect on μv and σi was discussed with respect to crystal structure and defect association. It was estimated that the crystal structure mainly governs these properties. The effect of defect association could not be ignored but is considered to be a complicated correlation. 相似文献
99.
制备了两种不同基质的掺杂3dZ2基态铜(Ⅱ)苯并15冠5配合物(Cu(Ⅱ)B15C5)的粉末样品,ESR测定结果表明,以B15C5为基质时,Cu(Ⅱ)B15C5的轴向配体是H2O;而以Mg(Ⅱ)B15C5为基质时的轴向配体则是CIO4-.不同的轴向配体对ESR谱的线型有着较大的影响。利用Bleaney公式,计算了键参数,并对成键特性进行了讨论和比较。 相似文献
100.
本文介绍一台采用双潘宁型多电荷重离子源的200kV重离子加速器,简述它在GaP光探测器的研制、聚合物材料和金属材料的离子注入改性等方面的研究与应用。 相似文献