296 research outputs found

    The Research on designing performance evaluation indexes system for Fujian W Private hospital

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    国内民营医院的发展一直面临着管理混乱、能力缺失、没有优势特色等一系列的问题,加上政策环境不利,使得民营医院难以得到长足发展。近几年,政府对社会办医越来越重视,并颁布了一系列政策,使得民营医院迎来了前所未有的机遇。找准战略定位,提升管理效率是民营医院抓住政策机遇寻求发展的两盏明灯,而其中符合医院战略定位的绩效评价体系是将战略落地并进行有效管理的重要手段。本文在分析福建W医院的内外部环境,已确定W医院发展战略的前提下,构建了基于平衡计分卡的绩效评价指标体系,从医院、科室、岗位三个层面分析了考核指标的建立。本文将平衡计分卡应用于我国民营医院的战略管理与绩效管理,并在平衡计分卡的设计中引入了医院知识管...The development of private hospitals has been facing a series of problems like management confusion, lack of ability, without advantage characteristic, as well as unfavorable policy environment, which made it difficult to obtain long-term development. In recent years, government paid more attention to social capital and a series of policies were promulgated,so that private hospitals ushered in an ...学位:会计硕士院系专业:管理学院_会计硕士学号:1752013115118

    Global Simulations of Enzymatic Catalysis

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    酶催化包括底物到活性区的输运、选择催化化学反应及产物释放等复杂过程,由于复杂的蛋白质环境效应,任一化学和非化学过程都有可能是决定酶活性的关键步骤; 。为了全面认识酶催化活性,我们对几类酶催化过程进行了广泛的组合量子/分子力学(QM/MM)和经典分子力学(MM)动力学模拟(MD)研究,详细地讨; 论了整个酶催化过程的分子机制、关键残基的作用和蛋白质环境效应,丰富了对酶催化活性的认识。随着多尺度模型和计算模拟方法的进一步完善与发展,有望实现; 超大复杂生物酶催化过程的全程模拟研究,为酶工程领域的相关研究提供支持。Enzymatic catalytic processes generally involve substrate delivery, selective catalytic reaction, and product release. Owing to the complex protein environment effect, any nonchemical or chemical step may determine the enzyme activity. Herein, to comprehensively understand enzymatic activity, extensive combined quantum mechanics/molecular mechanics (QM/MM) and molecular mechanics (MM) molecular dynamics ( MD) simulations were carried out on several kinds of enzymes. Possible reaction mechanisms, roles of the conserved residues, and effects of the protein environment on the whole enzymatic process are discussed in detail, which will enrich the knowledge of reactivity in proteins. With the improvement and development of multiscale models and computational methods, it is expected that global simulations of extremely large and complicated enzymes will enable and lend support to enzyme engineering.National Natural Science Foundation of China [21133007, 21373164,; 21172053

    类单晶硅结构Si(C≡C―C6H4―C≡C)4新材料的力学与光学性质:第一性原理研究

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    基于单晶硅中Si的四面体成键特征及对其结构单元的替换修饰,我们设计了一种类单晶硅结构的新材料-C40H16Si2。通过广泛的第一性原理计算,研究了这类材料的电子性质、力学性质和光学性质。计算结果表明,这种新材料具有好的热力学稳定性和机械稳定性。该材料的禁带宽度为3.32 eV,价带底和导带顶都位于Gamma点,是直接带隙宽禁带半导体材料。该材料的维氏硬度和密度非常小,不到单晶硅的十分之一,是一类低密度的柔性多孔材料。此外,该材料在紫外光区有强的吸收,有望应用于蓝绿光发光二极管。中央高校基本科研业务费专项资金(20720150215);;国家自然科学基金(21373164,21673185)资助项目~

    Unique Metal Di-Porphyrin Dyes with Excellent Photoelectronic Properties for Solar Cells: Insight from Density Functional Calculations

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    基于广泛的密度泛函理论计算,理论上设计并表征了一类新型的金属双卟啉染料.这些新型的卟啉染料具有很强的光捕获能力,且其低激态表现出优良的电荷分离性质.通过对这类染料体系的结构修饰,如包含不同金属的共轭大环(卟啉环或咔咯环)的取代,可以很容易地调控它们的光电子性质.计算表明,这类金属双卟啉染料的电子性质能很好地匹配不同的氧化还原电对,在染料太阳能敏化电池研究中具有好的应用前景.基于第一性原理计算,预测了金属双卟啉染料敏化TIO2体系的电子结构性质,讨论了可能的直接和间接电子注入机制,其间接电子注入时间约20 fS,电子注入过程非常快.A new type of metal di-porphyrin dyes have been designed and characterized by density functional calculations.Structural optimizations and subsequent frequency calculations for the isolated dyes were performed using the B3LYP hybrid functional in combination with the all-electron 6-31G(d) basis set.Bulk solvent effects were evaluated by using the continuum solvation model of SMD.Vertical excitation energies were computed by means of time-dependent density functional theory with CAM-B3LYP functional.The two-dimensional slab model of the most stable anatase TiO2(101) surface was used to calculate the structural and electronic properties of dye-TiO2system by using the plane-wave technique implemented in Vienna ab initio simulation package(VASP).The electron injection times from the dye to the semiconductor were estimated by using a model derived from the Newns-Anderson approach.Calculations show that these novel porphyrin-based sensitizers have a strong light harvesting ability and an excellent charge separation in the excited states.Their optical and charge-transfer properties can be well modulated by incorporating different metals and different conjugated macrocycles.Moreover, the more positive energy level of HOMO orbital of the metal di-porphyrin dye than the bottom of conduction band of TiO2ensures an effective electron injection from the excited dyes to TiO2, and its energy level of LUMO orbital can nicely match various redox couples to facilitate regeneration of the oxidized dyes.Accordingly the porphyrin-based complexes are quite promising for fabrication of the high performance dye-sensitized solar cells.Based on the first-principles calculations,plausible mechanisms for direct and indirect electron injections from the adsorbed dye to TiO2have been discussed.In the indirect process, the dye is initially promoted to the excited state with the charge separation under light excitation of relatively short wavelength region, followed by the electron transfer from the excited dye to TiO2.Such electron injection process is predicted to be very fast and the estimated electron injection times are only about 20 fs.The direct electron injection from dye to TiO2may occur under optical excitation in relatively long wavelength region.国家重点基础研究发展计划(973)项目(Nos.2011CB808504;2012CB214900); 国家自然科学基金(Nos.21133007;21373164); 贵州省科学基金(No.[2012]2151)资助~

    固定节面量子MonteCarlo的一个新算法

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    提出了一个固定节面量子MOnTECArlO的新算法,与前人的算法相比,其“指导函数”的优化不是在扩散前,而是在扩散过程中同步进行;这不仅在机时上是节省的,更重要的是优化与扩散两者按相同的取样方式进行,达到互相改善的目的;这一优化方案是超线性收敛的,它能加快粒子的扩散;在扩散过程中,“指导函数”的节面不断发生改变,这有利于减小“固定节面误差”.这一新算法已被运用到CH_2的X--3b_1态和A--1A_1态,以及nH_2的π-X--2b_1态和σ-A--2A_1态总能量的计算,由此算出了CH_2单一三重态的“劈开”能△E_(S-T)=(45.542±1.840)kJ/MOl和nH_2的σ-π“劈开”能△E_(σ-π)=(141.644±1.589)kJ/MOl.计算结果表明这一新算法在精度、统计误差和计算量方面比一般固定节面量子MOnTECArlO方法都要优越得多

    Carbon-doped zigzag boron nitride nanoribbons with widely tunable electronic and magnetic properties: insight from density functional calculations

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    First-principles calculations within the local spin-density approximation have been used to investigate the electronic and magnetic properties of carbon chain-doped zigzag born nitride nanoribbons (ZBNNRs). Our results indicate that doped half-bare ZBNNRs with an H-passivated B edge and a bare C edge generally have a spin-polarized ground state with the ferromagnetic spin ordering localized at the C edge, independent of the doping concentration and the ribbon width. In particular, doped half-bare ZBNNRs for all widths may produce half-semiconducting -> half-metallic -> metallic behavior transitions without an external electric field as the doping proceeds gradually from the N edge to the B edge. The breakage of the symmetric spin distribution in the bipartite lattice and the coexistence of the edge state and the border state arising from charge transfer in these doped ZBNNRs are responsible for their tunable electronic and magnetic properties.National Science Foundation of China [20673087, 20733002, 20873105]; Ministry of Science and Technology [2004CB719902

    Sequential covalent bonding activation and general base catalysis: insight into N-heterocyclic carbene catalyzed formylation of N-H bonds using carbon dioxide and silane

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    Ministry of Science and Technology [2011CB808504, 2012CB214900]; National Science Foundation of China [21133007]The detailed catalytic mechanisms of N-heterocyclic carbenes (NHCs) in the formylation of N-H bonds using carbon dioxide and silane were investigated using density functional theory (DFT) calculations. Among all the examined reaction pathways, we found that the most favorable pathway involves collaboration between the covalent bonding activation and general base catalysis. The overall reaction can be divided into four stages, including silane activation through a covalent bonding mechanism, CO2 insertion into the Si-H bond of silane to yield a key intermediate formoxysilane (FOS), the NHC-catalyzed coupling of amine and FOS through a general base mechanism, and C-O bond breaking through general base catalysis to obtain the final amide product. The carbamic acid anion (Me2NCOO-) is an inevitable intermediate from the side reactions, and its formation is almost barrier free. NHC can act as a base to abstract a proton from the nucleophiles (such as amines or alcohol), and facilitate C-N bond or C-O bond formation or cleavage, and such a general base mechanism is remarkably favorable over the covalent binding mechanism for C-N bond (or C-O) bond formation (or cleavage). The calculated thermodynamic properties are in good agreement with the available experimental findings

    Electronic spectra of linear isoelectronic species HC6H+, C6H, HC5N+

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    Multireference configuration interaction calculations have been used to determine term energies of low-lying doublet electronic states of isoelectronic carbon chains HC6H+, C6H and HC5N+. Calculations on relevant excited states in the energy range up to 6 eV show that (2)Pi and (2)Phi excited states due to the pi-pi excitation are comparable in energy pattern among such species, but that there are significant differences in the properties of (2)Sigma and (2)Delta excited state series of these isoelectronic species. Similarities and discrepancies are discussed based on molecular orbital energy patterns and electron correlation. The strongest transitions for HC6H+, C6H and HC5N+ are predicted to correspond to X(2)Pi -->2(2)Pi transitions at 2.22, 2.56 and 2.17 eV, respectively. For HC6H+, no (2)Sigma or (2)Delta states arising from sigma-pi electron promotion are found in the energy range up to 6 eV. However, in C6H the first excited state 1(2)Sigma (+) due to the 13 sigma -->3 pi excitation is found to be only slightly higher (0.22 eV) than the ground state X(2)Pi. Calculated transition energies in the present study show good agreement with available experimental results

    Structure, Energetics and Vibrational Frequency Shifts of Water Molecules Confined Inside Single-walled Carbon Nanotubes:A DFT Study

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    利用密度泛函理论中的杂化泛函M06-2X研究了受限于不同管径单壁碳纳米管(SWCnT)内水分子团簇(H2O)n=3~6的结构、能量以及振动频率.结果显示由于SWCnT的限域效应,水分子团簇的几何构型与在真空相比发生了巨大变化,如受限(H2O)6能形成单链锯齿型水分子构型.随着管直径的增大,纳米管与水之间的相互作用逐渐减弱,但水分子之间的氢键相互作用能变化不大.对比受限和真空下水分子O—H振动频率发现,绝大部分O—H的振动频率由于碳纳米管与水的相互作用而发生了红移.AIM理论分析显示O—H振动频率的红移应归因于其电子密度的减小.这也表明碳纳米管绝非简单的几何限制效应,而是与水分子之间存在弱电子相互作用,主要包括H…π氢键作用和O…π轨道作用,从而导致水分子的小部分电荷转移到了SWCnT上.The study of confined water molecules has attracted much attention because of their fascinating properties.In the present work, small water clusters(H2O)n=3~6 encapsulated in different diameter of single-walled carbon nanotubes(SWCNT) were investigated using density functional theory(DFT).The DFT-based M06-2X method along with mixed basis sets(6-311+G(d, p)//6-31+G(d)) was employed in all calculations for structure, interaction energy, charge transfer and vibrational frequency.The results indicate that as compared to water molecules in vacuum, the geometries of confined water molecules changed significantly due to the confinement effect of carbon nanotubes, for example, the(H2O)6 cluster can form chain-like configuration via hydrogen bond.The tube-water interaction energy decreased with the increase of the nanotubes diameter, while the hydrogen bond energy between water molecules changes slightly.Vibrational analysis reveals the red shift of the majority of the O—H stretching modes inside SWCNT compared to vacuum vibrational frequencies due to the tube-water interaction.The Bader's theory of atoms in molecule(AIM theory) has been used to characterize the tube-water interactions.Electron density ρ that reflects the strength of a bond has been used to explain the phenomenon of the red shift.The AIM analysis suggests that the red shift of O—H vibrational frequencies for confined water molecules should be attributed to the decrease of the electron density ρ.This fact demonstrates that the tube-water interaction is not a simple effect of geometry confinement, but weak electronic interaction between the molecular orbital of the confined water molecules and the delocalized π electrons from carbon nanotube.It mainly includes the H…π hydrogen bond interaction and O…π orbital interaction, resulting in a slight charge transfer from water molecules to SWCNT.Therefore, when constructing carbon nanotube devices, one should not ignore the existence of water molecules.We hope that our results can provide a guidance to the understanding of the behavior of water molecules encapsulated inside nanoscale environment.国家重点基础研究发展计划(No.2012CB214901); 国家自然科学基金(No.51274197)资助~

    化学反应的价键理论研究

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    根据价键波函数的对称性及基态、激发态化学键与键表的对应 ,可以把轨道对称守恒原理和键对称规律表述成“价键结构对称性匹配” .价键结构对称规则通过对反应物和产物的价键结构进行对称性分析 ,可以直接预测化学反应活性 ,无需依赖理论计算结果 .在价键结构对称性分析的基础上 ,应用多VB结构计算方法 ,建立了反应H +HLi→H2 +Li和H +LiH→HLiH(cyclic)→HLi+H的曲线交叉VB图 ,讨论了能垒及过渡态的形成机制 .计算结果表明 ,H原子交换反应H +LiH HLi+H是一个两步过程
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