二羟丙茶碱与牛血清白蛋白的相互作用及共存金属离子的影响

在优化的实验条件下,利用光谱法研究二羟丙茶碱(Di)和牛血清白蛋白(BSA)的相互作用和共存金属离子(Cu~(2+)、Fe~(3+)、Mn~(2+)、Ni~(2+)、Cr~(3+))对Di与BSA的相互作用的影响.结果表明:Di对BSA的荧光有猝灭作用,其猝灭过程属于静态猝灭.在290、305和320 K时分别计算结合常数、结合位点、Hill系数.根据热力学参数确定Di和BSA之间的作用力类型主要为氢键和范德华力.结合位点位于BSA的亚结构域ⅡA和ⅢA中,同步荧光光谱显示两者的结合位点更接近于色氨酸,同时研究了常见金属离子对二者作用的影响.     

二氢杨梅素铜配合物的合成及其与牛血清白蛋白的相互作用

合成了二氢杨梅素铜配合物(DMY-Cu),通过红外光谱、原子吸收法对其进行表征,并采用荧光光谱法研究了二氢杨梅素铜配合物与牛血清白蛋白(BSA)的相互作用.结果表明,DMY-Cu的组成为[C15H10O8Cu·H2O]n.激发波长为288nm时,BSA的发射峰位于345nm,DMY-Cu对BSA有较强的荧光猝灭作用,由温度对DMY-Cu与BSA体系荧光猝灭速率的影响和动态猝灭常数(KSU)以及静态猝灭结合常数(KA)的计算得出,DMY-Cu对BSA内源荧光的猝灭机制属于形成BSA-DMY-Cu复合物的静态猝灭,荧光猝灭常数为1.33×105L·mol-1;由反应前后热力学函数△Hθ＜0,△Sθ＞0推出DMY-Cu与BSA之间的作用力主要是静电作用力,在BSA分子上荧光敏感部位有1个结合位点,结合常数为4.95×105.     

光谱法研究盐酸利多卡因与牛血清白蛋白的相互作用及共存金属离子的影响

在模拟人体生理条件下,用紫外-可见吸收光谱法和荧光光谱法研究盐酸利多卡因(LH)和牛血清白蛋白(BSA)的相互作用及Mg~(2+)、Fe~(3+)、Cu~(2+)、Co~(2+)和Cr~(3+)对两者的结合作用的影响.结果表明:LH对BSA的荧光有猝灭作用,其猝灭过程属于动态猝灭.根据热力学参数确定了LH和BSA之间的作用力类型主要为氢键和范德华力.LH可以被BSA运输且结合位点位于BSA的亚螺旋域ⅢA中.Hill系数略大于1,表明LH对BSA的结合为较弱的正协同作用.LH对BSA构象产生微弱影响,结合位点更接近于酪氨酸.金属离子对结合产生促进作用,延长药物作用时间并减弱药物毒性.对揭示药物动力学问题及后续麻醉类药物的研发提供了理论依据.     

Cu~(2+)、Fe~(3+)、Zn~(2+)对香豆素-3-羧酸与牛血清白蛋白相互作用的影响

用荧光光谱法研究Cu~(2+)、Fe~(3+)、Zn~(2+)对香豆素-3-羧酸与牛血清白蛋白(BSA)相互作用的影响.结果表明:三种金属离子均能增强香豆素-3-羧酸对BSA的荧光猝灭及两者的结合作用,使体系的荧光猝灭常数、结合常数增大;Zn~(2+)的存在没有改变两者的作用力类型,仍以疏水作用力为主,Cu~(2+)、Fe~(3+)存在下,作用力变为以静电引力为主.表明Cu~(2+)、Fe~(3+)、Zn~(2+)对香豆素-3-羧酸与牛血清白蛋白的作用有重要影响.     

猪去氧胆酸与BSA相互作用研究

目的:采用荧光光谱法研究猪去氧胆酸(HDCA)与牛血清白蛋白(BSA)的相互作用.方法:根据25℃及37℃温度下HDCA对BSA的荧光猝灭作用,通过Stern-volmer方程和Lineweaver-Burk双倒数方程计算反应的猝灭常数和形成常数以判断荧光猝灭类型,采用双对数方程计算HDCA与BSA的结合常数(KA)和结合位点数(n),最后采用热力学公式计算反应前后焓变和熵变确定两者结合的主要作用力类型.结果:HDCA对BSA的荧光淬灭作用属于静态荧光淬灭.在温度25℃和37℃时,HDCA与BSA的结合常数分别为0.258×106 L·mol-1和0.453×104 L·mol-1,结合位点数分别0.92和0.62.由于热力学参数焓变(ΔH=-258.72 KJ·mol-1)和熵变(ΔS=-0.76 J·mol-1·K-1)均小于零,因此确定HDCA与BSA之间的作用力主要为氢键和范德华力作用.结论:HDCA与BSA通过氢键和范德华力形成复合物,经静态猝灭机制引起BSA内源性荧光猝灭.     

铝离子存在下槲皮素与牛血清白蛋白的相互作用

采用荧光光谱和同步荧光光谱研究Al~(3+)存在时,槲皮素(Qct)与牛血清白蛋白(BSA)之间的相互作用.实验结果表明,Al~(3+)存在,能够增强槲皮素对BSA的荧光猝灭程度、使槲皮素与BSA的结合常数增大、影响了槲皮素对BSA的荧光猝灭类型、没有改变槲皮素与BSA的作用力类型.Al~(3+)的引入使蛋白质分子肽链更加紧缩,疏水性增加.     

盐酸川芎嗪与牛血清白蛋白相互作用的研究及共存金属离子的影响

在优化的实验条件下,利用光谱法研究盐酸川芎嗪(LH)和牛血清白蛋白(BSA)的相互作用和共存金属离子(Mg2+、Cu2+、Zn2+、Ni2+、Fe3+)对LH与BSA相互作用的影响.结果表明:LH对BSA的荧光有猝灭作用,其猝灭过程属于静态猝灭.通过计算得出LH与BSA的结合常数Kb及结合位点数n.根据热力学参数确定了LH与BSA之间的作用力类型主要为疏水作用力.结合位点位于BSA的亚结构ⅡA中,Hill系数nH1,表明LH有弱的负协同作用.同步荧光光谱显示两者的结合位点更接近于色氨酸,同时也研究了金属离子对二者作用的影响.为后续吡嗪类药物的研发和进一步探讨LH在生物体内与蛋白质的作用机制和生物学效应提供了理论依据.1     

稀土钐离子与牛血清白蛋白相互作用研究

利用荧光光谱法研究了稀土钐离子(Sm~(3+))与牛血清白蛋白(BSA)的相互作用,探讨了不同pH值的缓冲溶液和不同钐离子浓度对BSA荧光强度的影响.通过改变钐离子标准溶液浓度范围,扫描Sm~(3+)与牛血清白蛋白相互作用的荧光发射光谱,证实了稀土钐离子(Sm~(3+))对BSA的荧光猝灭属于静态猝灭.利用荧光猝灭的Stern-Volmer方程和静态猝灭公式线性拟合,求得反应的荧光猝灭过程速率常数K_q=4.12×10~(12) L·mol~(-1)·s~(-1),结合常数K_a=9.652×10~5 L·mol~(-1),结合数n=1.22.     

光谱法研究盐酸洛贝林与牛血清白蛋白的相互作用及共存金属离子的影响

目的:盐酸洛贝林(LH)与牛血清白蛋白(BSA)的相互作用及共存金属离子的影响.方法:在优化的实验条件下,利用荧光、同步荧光和紫外可见光谱法研究LH与BSA的相互作用及共存金属离子的影响.结果:LH能猝灭BSA的荧光,遵循动态猝灭过程.由于有1个结合位点,BSA能运输LH.焓为负值,熵为正值,表明在结合过程中氢键和范德华力起主要作用.另外,它是一个自发放热过程.BSA的亚螺旋域ⅡA是主要结合位置,离酪氨酸残基更近.结论:有微弱的药物正协同作用.LH对BSA构象产生影响.Mg~(2+)、Co~(2+)、Cu~(2+)、Ni~(2+)和Mn~(2+)对LH与BSA结合产生促进作用,延长药效时间.该研究为LH的临床研究提供一定的参考依据.     

光谱法研究利培酮与牛血清白蛋白的相互作用及共存金属离子的影响

在模拟人体生理条件下,采用多种光谱法研究了牛血清白蛋白(BSA)与利培酮(RI)猝灭反应的信息.研究表明:加入RI后,通过动态猝灭机制,BSA的荧光强度明显下降.通过计算得出RI与BSA的速率常数(Kq)、猝灭常数(Ksv)、结合位点数(n)、结合常数(Kc)和Hill系数(nH).使用范托夫方程测定热力学参数、焓变化(ΔH),熵变(ΔS)和吉布斯自由能(ΔG).结果表明,RI与BSA的相互作用是自发的.静电作用力是主要的作用力类型.同步荧光光谱表明结合位点更接近于色氨酸,RI对BSA构象产生一定的影响.RI与BSA的结合位点主要位于BSA的亚螺旋域ⅡA中.nH≈1,表明RI分子之间对结合反应几乎无协同作用.同时还探讨了共存金属离子对RI与BSA结合作用的影响.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the