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1.
使用Gaussian 98程序包、在B3LYP/6-311++G**基组水平上对各物种进行全优化的基础上,用振动模式分析对1-丙烯基和NO反应的机理进行了充分阐明. 该反应体系共有7个反应通道和5组小分子最终产物,CH2O+CH3CN、CH2CHCN+H2O、CH3CHO+HCN、CH3CHO+HNC以及CH3CCH+HNO. 研究表明,反应通道C3H5¢+NO→IM1→TS1→IM2→TS2→IM3→TS3→CH3CHO+HCN在能量上是最为可行的. 相似文献
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利用abinitio方法对CH3CH2+O(3P)反应进行了理论研究,在MP2/6311+G(d,p)水平上优化得到了反应途径上的反应物、中间体、过渡态和产物的几何构型和谐振频率,并在QCISD(T)/6311+G(d,p)水平上进行单点能计算.计算结果表明:CH2O+CH3、CH3CHO+H和CH2CH2+OH是主要反应产物,其中CH2O+CH3主要来自反应通道A1:(R)→IM1→TS3→(A),CH3CHO+H主要来自反应通道B1:(R)→IM1→TS4→(B),CH2CH2+OH主要来自直接抽提反应通道C1和C2:(R)→TS1(TS2)→(C).计算结果同时表明该反应生成CO的通道能垒是非常高的,CO应该不是主要产物. 相似文献
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用时间分辨傅立叶红外光谱法和量子化学计算,研究了CH3自由基与NO2的基元反应.由248 nm激光光解CH3Br或CH3I得到CH3自由基.首次观测到了振动激发的产物OH、HNO和CO2.另一产物NO也被证实.由此确定了反应通道CH3O+NO,CH2NO+OH 和HNO+H2CO.其中CH3O+NO是主要的反应通道.还用CCSD(T)/6-311++G(df,p)//MP2/6-311G(d,p)的方法对上述通道的机理在理论上做了研究.理论计算的结果与实验观察相符. 相似文献
4.
靳玲侠 《原子与分子物理学报》2019,36(6)
采用CCSD(T)/cc-pVTZ//B3LYP/6-311++G(2df,2p)水平上对CH3CHOH + HO2和CH3CH2O + HO2反应体系的单、三重态反应机理进行了详细的理论研究.计算结果表明,CH3CHOH + HO2反应主要发生在单重态势能面上,其中四条通道均为快速自发过程;CH3CH2O + HO2反应在三重态势能面上的通道CH3CH2O + HO2 → 3IM11 → 3TS11 → P11 (CH3CH2OH + 3O2)为动力学和热力学的优势路径. 大气中CH3CHOH比CH3CH2O更容易稳定存在. 相似文献
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靳玲侠 《原子与分子物理学报》2018,35(6)
采用CCSD(T)/cc-pVTZ//B3LYP/6-311++G(2df,2p)水平上对CH3CHOH + HO2和CH3CH2O + HO2反应体系的单、三重态反应机理进行了详细的理论研究.计算结果表明,CH3CHOH + HO2反应主要发生在单重态势能面上,其中四条通道均为快速自发过程;CH3CH2O + HO2反应在三重态势能面上的通道CH3CH2O + HO2 → 3IM11 → 3TS11 → P11 (CH3CH2OH + 3O2)为动力学和热力学的优势路径. 大气中CH3CHOH比CH3CH2O更容易稳定存在. 相似文献
6.
利用abinitio方法对CH3CH2+N(4S)反应进行了理论研究,在MP2/6-311+G(d,p)水平上优化得到了反应途径上的反应物、中间体、过渡态和产物的几何构型和谐振频率,并在QCISD(T)/6-311+G(d,p)水平上进行单点能计算.计算结果表明,CH2CH2+3NH和H2CN+CH3是此反应主要产物,CH3CHN+H是此反应次要产物.产物CH2CH2+3NH主要来自直接氢抽提反应通道,H2CN+CH3来自加成-解离反应通道,CH3CHN+H来自加成-解离反应通道. 相似文献
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本文采用实验测量和数值模拟结合的方法,对AC放电下He/CH4/O2混合气中激发态对甲烷裂解和低温氧化的动力学贡献进行研究。基于HP-Mech,增加反应物的放电机理以及激发态参与的化学反应及其驰豫反应,建立CH4低温氧化机理。采用化学反应动力学求解器CHEMKIN中的两段式Plasma-PSR模型模拟放电过程及化学反应过程。该动力学模型能较好地预测反应物的消耗和主要产物的生成,反应路径分析表明激发态物质CH4(v),O2(v),O2(a^1△g)等通过链式反应CH4(v)+OH→CH3+H2O,O2(v)+H→OH+O,O2(a^1△g)+H→OH+O促进活性自由基和产物的生成。 相似文献
8.
采用密度泛函理论B3LYP 方法研究了CF2 自由基与HNCO 的反应机理, 并在B3LYP/6-311++G**水平上对反应物、中间体、过渡态进行了全几何参数优化, 通过频率分析和内禀反应坐标(IRC)确定了中间体和过渡态.为了得到更精确的能量值, 又用CCSD(T)/6-311++G**方法计算了在B3LYP/6-311++G**水平优化后的各个驻点的相对能量. 根据统计热力学及用Winger校正的Eyring过渡态理论,利用自编程序,计算不同温度下低势垒反应的平衡常数和速率常数.计算结果表明单重态的CF2 自由基与HNCO 的反应有四条反应通道, 三重态的CF2 自由基与HNCO 的反应有两条反应通道.其中单重态反应通道CF2+HNCO→1IM1→1TS1→1IM2→1TS2→1IM3→CF2NH+CO(P1)为主反应通道.三重态反应通道CF2+HNCO→36IM1→36TS1→36IM2→HCF2+NCO(3P5)为主反应通道. 相似文献
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采用密度泛函理论B3LYP 方法研究了CF2 自由基与HNCO 的反应机理, 并在B3LYP/6-311++G**水平上对反应物、中间体、过渡态进行了全几何参数优化, 通过频率分析和内禀反应坐标(IRC)确定了中间体和过渡态.为了得到更精确的能量值, 又用CCSD(T)/6-311++G**方法计算了在B3LYP/6-311++G**水平优化后的各个驻点的相对能量. 根据统计热力学及用Winger校正的Eyring过渡态理论,利用自编程序,计算不同温度下低势垒反应的平衡常数和速率常数.计算结果表明单重态的CF2 自由基与HNCO 的反应有四条反应通道, 三重态的CF2 自由基与HNCO 的反应有两条反应通道.其中单重态反应通道CF2+HNCO→1IM1→1TS1→1IM2→1TS2→1IM3→CF2NH+CO(P1)为主反应通道.三重态反应通道CF2+HNCO→36IM1→36TS1→36IM2→HCF2+NCO(3P5)为主反应通道. 相似文献
10.
利用abinitio方法对SiH3+O(3P)反应进行了理论研究,在MP2/6-311+G(d,p)水平上优化得到了反应途径上的反应物、中间体、过渡态和产物的几何构型,并在QCISD(T)/6-311+G(d,p)水平上进行单点能计算.计算结果表明,SiH3+O(3P)→IM1→TS3→IM2→TS8→HOSi+H2为主反应通道,其他可能存在的次要产物有HSiOH+H、H2SiO+H和HSiO+H2.HOSi、HSiO和HSiOH(cis)还可能进一步解离生成SiO.另外,计算结果对SiH4+O(3P)反应机理中存在的争议给出了可能的解释,认为Withnall等人在实验中观察到的产物HSiOH、H2SiO和SiO并不是SiH4+O(3P)反应的直接产物,而是来自副反应SiH3+O(3P). 相似文献
11.
应用NMR技术,其中包括:1H NMR、13C NMR、DEPT、COSY、13C-1H COSY和HMBC,对联萘酚磷酰胺的一对差向异构体的结构进行了研究.对S-R及R-R差向异构体的所有碳氢信号进行了一一归属,并依此考查了差向异构体的构象,分析结果得到了X-ray单晶衍射结果的证实. 相似文献
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Dual mechanisms of Bcl-2 regulation in IP3-receptor-mediated Ca2+ release: A computational study 下载免费PDF全文
Inositol 1,4,5-trisphosphate receptors (IP3R)-mediated calcium ion (Ca2+) release plays a central role in the regulation of cell survival and death. Bcl-2 limits the Ca2+ release function of the IP3R through a direct or indirect mechanism. However, the two mechanisms are overwhelmingly complex and not completely understood. Here, we convert the mechanisms into a set of ordinary differential equations. We firstly simulate the time evolution of Ca2+ concentration under two different levels of Bcl-2 for the direct and indirect mechanism models and compare them with experimental results available in the literature. Secondly, we employ one- and two-parameter bifurcation analysis to demonstrate that Bcl-2 can suppress Ca2+ signal from a global point of view both in the direct and indirect mechanism models. We then use mathematical analysis to clarify that the indirect mechanism is more efficient than the direct mechanism in repressing Ca2+ signal. Lastly, we predict that the two mechanisms restrict Ca2+ signal synergistically. Together, our study provides theoretical insights into Bcl-2 regulation in IP3R-mediated Ca2+ release, which may be instrumental for the successful development of therapies to target Bcl-2 for cancer treatment. 相似文献
13.
Critical behavior of quasi two-dimensional organic-inorganic halide perovskites (C6H5CH2CH2NH3)2CuCl4 is investigated using magneto-thermal and isothermal magnetic properties along the easy axis. Banerjee's criterion indicates that phase transition from paramagnetic to ferromagnetic phases below TC = 9.4 K is of second-order. Scaling analysis reveals that critical exponent β from spontaneous magnetization in the critical region below TC and δ from critical isotherm at TC are found to be 0.22(3) and 9.28–9.4, close to 2D finite XY model. Meanwhile, γ from magnetic susceptibility in the critical region above TC is gradually decreased from 2.4 at high-temperature region. Critical exponents from magneto-thermal properties are found to be consistent with those determined from magnetization isotherms. The reliability of critical values is verified using the scaling hypothesis. Our results evidence that (C6H5CH2CH2NH3)2CuCl4 crossovers from isotropic 2D Heisenberg to anisotropic 3D models towards TC and can be promising candidates for magnetocaloric materials for hydrogen reliquefaction. 相似文献
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G. A. Crowder 《光谱学快报》2013,46(7):805-813
Infrared and Raman spectra were obtained for 2, 3, 3-trimethylhexane and were interpreted with the aid of normal coordinate calculations. It was concluded that this compound exists in three molecular conformations, but a fourth conformer may exist. Vibrational assignments were made for the three conformers. 相似文献
16.
Both two-dimensional (2D) Windowed Fourier Transform and 2D S Transform are popular time–frequency analysis tools for processing signals. But fewer articles reported the application of 2D S Transform in Fringe pattern analysis. This paper studies the 2D S Transform and compares it with 2D Windowed Fourier Transform. The phase calculation formula based on the 2D Windowed Fourier Transform “ridge” coefficients and 2D S Transform “ridge” coefficients are deduced respectively. A comparison between them is carried out to show their own characteristic in fringe patterns analysis based on the structured-light illumination. It verifies that the 3D reconstruction result of 2D ST is better than that of 2D WFT because of the employment of the adjusted windows by frequency parameters. 相似文献
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利用ANSYS有限元软件,分别采用静态及动态分析方法对HL-2M装置极向场线圈支撑结构进行了分析,获得了典型工况载荷作用下的应力分布、位移及变形。结果表明,支撑结构能够满足装置的设计要求。为进一步优化支撑结构提供了参考数据。 相似文献
19.
V. Sedykh V. Sh. Shekhtman I. S. Smirnova B. Sh. Bagautdinov E. V. Suvorov A. V. Dubovitskii 《Physica C: Superconductivity and its Applications》2003,390(4):311-320
The single-crystalline specimens of the Fe-doped (5% 57Fe) Bi2Sr2CaCu2O8 (2212Cu) compound have been synthesized to compare the behavior of the structure modulation in Bi-cuprate and Bi-ferrate compounds. According to the Mössbauer data obtained, one can conclude that extra oxygen, related to the presence of Cu3+ in 2212Cu, is most probably arranged in the Ca layer rather than in the Bi layer, as was supposed in the model of extra oxygen. Based on the analysis of the experimental data we propose the explanation of the structure modulation in Bi compounds. Due to the mismatch between the internal perovskite block and the external BiO layers the structure of the Bi compounds is distorted. The Sr layer being boundary between these blocks probably is most distorted and stressed. We suppose that the different changes related to the modulation can occur just in this layer. The Bi excess, which is always present in Bi compounds (especially in single crystals), can be just the necessary condition at which the modulation appears. Extra oxygen in principle can be present in modulated structures. However, in our opinion, it only complements the influence of other factors and is not the driving force in the structure modulation. 相似文献
20.
钙离子(Ca~(2+))是生物体内一种"生死攸关"的信号分子,Bcl-2蛋白可以直接或间接调节IP_3R通道释放Ca~(2+)的能力,借此决定细胞命运.本文基于新近的实验成果,针对Bcl-2蛋白间接调控Ca~(2+)的信号通路建立数学模型,得到了与实验数据相符合的结果,从理论上证明了Bcl-2蛋白对钙信号有抑制作用.在对模型进行鲁棒性检验之后,本文对该信号通路中一些关键组分的作用进行了预测.以[IP_3]和[Bcl-2]为双分岔参数分析的结果表明Bcl-2对刺激强度能产生Ca~(2+)振荡的区域有重要影响.以蛋白磷酸酶1[PP1]和蛋白激酶A[PKA]为单分岔参数分析的结果揭示:PP1可以有效地抑制钙信号,而PKA对钙信号的促进作用有一定的局限性.模型结果表明,不同浓度组合的IP_3,Bcl-2和PKA会对钙信号发挥复杂的调控作用.本文不仅对相关生物学实验有一定的指导作用,而且可为治疗因钙信号失调而导致的疾病提供思路. 相似文献