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By combing the time-dependent density functional calculations for electrons with molecular dynamics simulations for ions (TDDFT-MD) nonadiabatically in real time, we investigate the microscopic mechanism of collisions between cytosine and low-energy protons with incident energy ranging from 150 eV to 1000 eV. To explore the effects of the collision site and the proton incident energy on irradiation processes of cytosine, two collision sites are specially considered, which are N and O both acting as the proton receptors when forming hydrogen bonds with guanine. Not only the energy loss and the scattering angle of the projectile but also the electronic and ionic degrees of freedom of the target are identified. It is found that the energy loss of proton increases linearly with the increase of the incident energy in both situations, which are 14.2% and 21.1% of the incident energy respectively. However, the scattering angles show different behaviors in these two situations when the incident kinetic energy increases. When proton collides with O, the scattering angle of proton is larger and the energy lost is more, while proton captures less electrons from O. The calculated fragment mass distribution shows the high counts of the fragment mass of 1, implying the production of H+ fragment ion from cytosine even for proton with the incident energy lower than keV. Furthermore, the calculated results show that N on cytosine is easier to be combined with low-energy protons to form NH bonds than O. 相似文献
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手性硫醚是一类重要的精细化工产品.以L-天冬氨酸为原料,在冰水浴中经重氮化、氯代,得到中间产物L-2-氯琥珀酸.继而与Na2S进行硫醚化反应得到产物(+)-2R,2'S-硫代二琥珀酸.反应总收率40.1%,产品经1H-NMR检测确认,[αD20]=+27.3(c=1.0,DMSO),光学纯度99.3%.从而引进了一种以天然氨基酸为手性源,定向合成手性硫醚的方法. 相似文献
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以环氧环己烷作为改性单体,通过环氧氯丙烷与环氧环己烷阳离子开环聚合获得分子量约为3000的共聚醚主链。然后以联苯为介晶基元、亚氨基二乙酸为末端螯合基团,成功合成了一种新型结构的侧链液晶聚醚螯合树脂。在对其结构鉴定以及基础物理性质测定的基础上,系统地研究了该树脂对水中Cu2+吸附的影响因素、再生性能、吸附选择性、吸附模型以及吸附动力学。结果表明,该树脂对Cu2+具有良好的吸附性能、再生性能和选择性,其对水中Cu2+的吸附为Langmuir单分子层吸附,吸附过程符合准二级动力学模型。 相似文献
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手性硫醚是一类重要的精细化工产品.以L-天冬氨酸为原料,在冰水浴中经重氮化、氯代,得到中间产物L-2-氯琥珀酸.继而与Na。S进行硫醚化反应得到产物(+)-2R,2’S-硫代二琥珀酸.反应总收率40.1%,产品经。H—NMR检测确认,[αD^20]=+27.3(c=1.0,DMSO),光学纯度99.3%.从而引进一种以天然氨基酸为手性源,定向合成手性硫醚的方法. 相似文献
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