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Modeling hydrogen exchange of proteins by a multiscale method
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作者 祝文涛 李文飞 王炜 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第7期93-99,共7页
We proposed a practical way for mapping the results of coarse-grained molecular simulations to the observables in hydrogen change experiments.By combining an atomic-interaction based coarse-grained model with an all-a... We proposed a practical way for mapping the results of coarse-grained molecular simulations to the observables in hydrogen change experiments.By combining an atomic-interaction based coarse-grained model with an all-atom structure reconstruction algorithm,we reproduced the experimental hydrogen exchange data with reasonable accuracy using molecular dynamics simulations.We also showed that the coarse-grained model can be further improved by imposing experimental restraints from hydrogen exchange data via an iterative optimization strategy.These results suggest that it is feasible to develop an integrative molecular simulation scheme by incorporating the hydrogen exchange data into the coarse-grained molecular dynamics simulations and therefore help to overcome the accuracy bottleneck of coarse-grained models. 展开更多
关键词 coarse-grained model hydrogen exchange multiscale method PROTEINS integrative molecular simulations
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乙烯-醋酸乙烯共聚物接枝聚苯乙烯的制备及性能 被引量:4
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作者 蒋丽萍 袁悦 +2 位作者 张健夫 李文斐 姚占海 《高分子材料科学与工程》 EI CAS CSCD 北大核心 2019年第8期36-41,共6页
采用预辐照与悬浮接枝聚合技术制备了乙烯-醋酸乙烯共聚物(EVA)接枝聚苯乙烯共聚物(EVA-g-PS)。利用傅里叶变换红外光谱(FT-IR)、核磁共振氢谱(1H-NMR)、差示扫描量热和透射电子显微镜、力学性能测试、高温老化试验等对EVA和EVA-g-PS的... 采用预辐照与悬浮接枝聚合技术制备了乙烯-醋酸乙烯共聚物(EVA)接枝聚苯乙烯共聚物(EVA-g-PS)。利用傅里叶变换红外光谱(FT-IR)、核磁共振氢谱(1H-NMR)、差示扫描量热和透射电子显微镜、力学性能测试、高温老化试验等对EVA和EVA-g-PS的结构、性能进行了研究。结果表明,在EVA-g-PS的FT-IR谱图中,700cm^-1、755cm^-1、1480cm^-1、1602cm^-1及3060cm^-1处都出现了吸收峰,而且在EVA-g-PS的1H-NMR谱图的化学位移δ6~8之间有5组峰出现,均可证明聚苯乙烯(PS)与EVA接枝成功;随着接枝率提高,接枝物结晶能力及高温稳定性降低;当接枝率为76.7%时,接枝物中双键明显增多,粒径分布一致,说明PS分布均匀;相比于EVA,接枝物的抗老化性及加工性能均得到提高。 展开更多
关键词 乙烯-醋酸乙烯共聚物 聚苯乙烯 预辐照 接枝率
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预辐照聚乙烯与甘油单硬脂酸单丙烯酸二酯接枝物的制备及性能 被引量:1
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作者 李眉远 李文斐 姚占海 《高分子材料科学与工程》 EI CAS CSCD 北大核心 2020年第2期1-6,共6页
通过预辐照和二次接枝的方法制备了不同浓度线型低密度聚乙烯(LLDPE)与流滴剂甘油单硬脂酸单丙烯酸二酯(GMSAA)的二次接枝物(L2G)。利用红外光谱仪、差示扫描量热仪、材料实验机、液滴形状分析仪、扫描电子显微镜及加速流滴测试仪对其... 通过预辐照和二次接枝的方法制备了不同浓度线型低密度聚乙烯(LLDPE)与流滴剂甘油单硬脂酸单丙烯酸二酯(GMSAA)的二次接枝物(L2G)。利用红外光谱仪、差示扫描量热仪、材料实验机、液滴形状分析仪、扫描电子显微镜及加速流滴测试仪对其结构与性能进行表征。结果表明,L2G的红外光谱在1635 cm-1处特征吸收峰消失,1730 cm-1处产生1个新的特征吸收峰,证明GMSAA已接枝到LLDPE分子链上;L2G的接枝率为1.74%,与一次接枝物相比,提高了51.3%;与LLDPE相比,L2G的结晶温度(Tc)升高,熔融温度(Tm)和力学性能没有大的变化;L2G/LLDPE/EVA膜在60℃时加速流滴期最长为24 d,是相同条件掺混的1.41倍。 展开更多
关键词 聚乙烯 二次接枝 流滴 预辐照
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Computational prediction of RNA tertiary structures using machine learning methods 被引量:1
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作者 黄斌 杜渊洋 +3 位作者 张帅 李文飞 王骏 张建 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第10期17-23,共7页
RNAs play crucial and versatile roles in biological processes. Computational prediction approaches can help to understand RNA structures and their stabilizing factors, thus providing information on their functions, an... RNAs play crucial and versatile roles in biological processes. Computational prediction approaches can help to understand RNA structures and their stabilizing factors, thus providing information on their functions, and facilitating the design of new RNAs. Machine learning (ML) techniques have made tremendous progress in many fields in the past few years. Although their usage in protein-related fields has a long history, the use of ML methods in predicting RNA tertiary structures is new and rare. Here, we review the recent advances of using ML methods on RNA structure predictions and discuss the advantages and limitation, the difficulties and potentials of these approaches when applied in the field. 展开更多
关键词 RNA structure prediction RNA scoring function knowledge-based potentials machine learning convolutional neural networks
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RNAGCN:RNA tertiary structure assessment with a graph convolutional network
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作者 邓成伟 唐蕴芯 +3 位作者 张建 李文飞 王骏 王炜 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第11期155-163,共9页
RNAs play crucial and versatile roles in cellular biochemical reactions.Since experimental approaches of determining their three-dimensional(3D)structures are costly and less efficient,it is greatly advantageous to de... RNAs play crucial and versatile roles in cellular biochemical reactions.Since experimental approaches of determining their three-dimensional(3D)structures are costly and less efficient,it is greatly advantageous to develop computational methods to predict RNA 3D structures.For these methods,designing a model or scoring function for structure quality assessment is an essential step but this step poses challenges.In this study,we designed and trained a deep learning model to tackle this problem.The model was based on a graph convolutional network(GCN)and named RNAGCN.The model provided a natural way of representing RNA structures,avoided complex algorithms to preserve atomic rotational equivalence,and was capable of extracting features automatically out of structural patterns.Testing results on two datasets convincingly demonstrated that RNAGCN performs similarly to or better than four leading scoring functions.Our approach provides an alternative way of RNA tertiary structure assessment and may facilitate RNA structure predictions.RNAGCN can be downloaded from https://gitee.com/dcw-RNAGCN/rnagcn. 展开更多
关键词 RNA structure predictions scoring function graph convolutional network deep learning RNA-puzzles
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Religion and stock price crash risk:Evidence from China 被引量:7
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作者 wenfei li Guilong Cai 《China Journal of Accounting Research》 2016年第3期235-250,共16页
This paper investigates whether religious traditions influence firm-specific crash risk in China.Using a sample of A-share listed firms from 2003 to 2013,we provide evidence that the more intense the religious environ... This paper investigates whether religious traditions influence firm-specific crash risk in China.Using a sample of A-share listed firms from 2003 to 2013,we provide evidence that the more intense the religious environment,the lower the stock price crash risk,implying that religion plays an important role in Chinese corporate governance.Further,we find that(1) religion affects stock price crash risk by reducing earnings management and the management perk problem;(2) different religions have different effects,and Taoism,in particular,is unrelated to crash risk; and(3) the effects of religion are more pronounced with higher quality corporate governance and a stronger legal environment.Religion constrains the management agency problem,thus reducing stock price crash risk in China.Our paper enriches the literature on stock price crash risk and religion,and on new economic geography. 展开更多
关键词 RELIGIOUS environment Stock price CRASH risk INFORMAL INSTITUTION CORPORATE governance
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Does executives’overseas experience improve firms’labor investment efficiency?
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作者 wenfei li Manlin Rong Jing Wu 《China Journal of Accounting Research》 2023年第4期123-145,共23页
Based on upper echelons theory and using a sample of private Chinese A-share listed firms from 2008 to 2020,this paper studies the impact of executives’overseas experience on firms’labor investment efficiency.The re... Based on upper echelons theory and using a sample of private Chinese A-share listed firms from 2008 to 2020,this paper studies the impact of executives’overseas experience on firms’labor investment efficiency.The results show that executives with overseas experience significantly enhance firms’labor investment efficiency.After distinguishing between different types of overseas experience,the results show that executives with only study experience or with both study and work experience abroad have a significant positive effect on firms’labor investment efficiency,while executives with only overseas work experience have no significant effect.A cross-sectional analysis based on labor adjustment costs shows that the positive impact of executives’overseas experience is more pronounced in labor-intensive firms,firms with a greater proportion of R&D investment and firms with a higher percentage of highly educated employees.The mechanism tests show that executives with overseas experience can optimize labor investment efficiency by lowering agency costs,attracting analyst attention and alleviating financing constraints under conditions of underemployment.This study enriches the literature on the characteristics of executive teams and the efficiency of labor investment,providing reference and inspiration for firms to attract more high-quality returnees and optimize their labor resource allocation. 展开更多
关键词 Overseas experience Labor investment efficiency Upper echelons theory
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18F-FDG PET/CT与增强CT在成人原发前纵隔恶性肿瘤中的诊断价值 被引量:2
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作者 陈涛 樊建中 +1 位作者 李文菲 吴彩云 《国际放射医学核医学杂志》 2020年第9期548-553,共6页
目的探讨18F-氟脱氧葡萄糖(FDG)PET/CT与增强CT在成人原发前纵隔恶性肿瘤中的诊断价值,以提高对该部位病变的诊断水平。方法回顾性分析2016年6月至2019年5月在湖北文理学院附属医院(襄阳市中心医院)经病理证实的成人原发前纵隔肿瘤患者8... 目的探讨18F-氟脱氧葡萄糖(FDG)PET/CT与增强CT在成人原发前纵隔恶性肿瘤中的诊断价值,以提高对该部位病变的诊断水平。方法回顾性分析2016年6月至2019年5月在湖北文理学院附属医院(襄阳市中心医院)经病理证实的成人原发前纵隔肿瘤患者80例(恶性肿瘤35例、良性肿瘤45例),其中,男性46例、女性34例,年龄20~80(45.5±10.2)岁。所有患者均行全身18F-FDG PET/CT及胸部CT平扫+增强扫描,2种检查的间隔时间在2周内。分别计算并采用χ2检验比较18F-FDG PET/CT与增强CT扫描的诊断灵敏度、特异度和准确率,采用χ2检验比较2种检查方法对不同类型恶性肿瘤的诊断效能。结果35例恶性肿瘤中胸腺癌15例,淋巴瘤10例,恶性生殖细胞瘤7例,神经内分泌癌、恶性黑色素瘤及滑膜肉瘤各1例。18F-FDG PET/CT诊断成人原发前纵隔恶性肿瘤的灵敏度[97.1%(34/35)]、特异度[93.3%(42/45)]及准确率[95.0%(76/80)]均高于增强CT[71.4%(25/35)、77.8%(35/45)、75.0%(60/80)],且差异有统计学意义(χ2=8.612、4.357、12.471,均P<0.05);18F-FDG PET/CT对胸腺癌、淋巴瘤及恶性生殖细胞瘤诊断的准确率[93.3%(14/15)、100.0%(10/10)、85.7%(6/7)]均高于增强CT[60.0%(9/15)、50.0%(5/10)、28.6%(2/7)],且差异有统计学意义(χ2=4.503、6.333、4.333,均P<0.05)。结论18F-FDG PET/CT对成人原发前纵隔恶性肿瘤具有重要的诊断价值,其诊断效能优于增强CT,可作为该病主要的检查方法。 展开更多
关键词 肿瘤 正电子发射断层显像术 体层摄影术 X线计算机 氟脱氧葡萄糖F18 前纵隔
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混合所有制改革、公司治理与国有企业分红 被引量:22
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作者 黎文飞 马新啸 蔡贵龙 《会计与经济研究》 CSSCI 北大核心 2020年第4期59-78,共20页
文章以2008−2015年沪深两市国有上市公司为样本,采用非国有股东持股比例和非国有股东委派董事比例衡量国有企业混合所有制改革,研究发现混合所有制改革对国有企业分红行为具有积极的促进作用:非国有股东委派董事比例增加,国有企业的分... 文章以2008−2015年沪深两市国有上市公司为样本,采用非国有股东持股比例和非国有股东委派董事比例衡量国有企业混合所有制改革,研究发现混合所有制改革对国有企业分红行为具有积极的促进作用:非国有股东委派董事比例增加,国有企业的分红意愿和分红水平显著提高,且这一正向关系在中央企业与地方国有企业、垄断与竞争行业间没有表现出显著差异;非国有股东持股比例对国有企业分红行为的影响较弱。进一步研究发现混合所有制改革的治理效果受管理层权力和投资者法律保护的影响:当管理层权力较弱或投资者法律保护较强时,非国有股东委派董事对国有企业分红行为的促进作用更加明显。结论表明,引入非国有股东的混合所有制改革能够提高国有企业治理水平,保障中小投资者权益,促进资本市场健康发展。 展开更多
关键词 混合所有制改革 国有企业分红 非国有股东 公司治理
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Identifying M&A targets and the information content of VC/PEs 被引量:1
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作者 Qingquan Tang wenfei li 《China Journal of Accounting Research》 2018年第1期33-50,共18页
The information gap in the M&A market hinders acquirers from effectively identifying high-quality targets. We examine whether VC/PEs convey information content in the M&A market and whether acquirers can use s... The information gap in the M&A market hinders acquirers from effectively identifying high-quality targets. We examine whether VC/PEs convey information content in the M&A market and whether acquirers can use such information to identify high-quality targets. We show that VC/PEs have significant information content and can signal high-quality target companies via ‘‘certification". When acquirers lack acquisition experience and targets are located in inferior information environments, VC/PE ‘‘certification" is more significant.The better reputation a VC/PE has, the more information it conveys. Syndicate VC/PEs convey stronger information than independent VC/PEs. We also find that acquirers do not pay higher premiums for high-quality targets. Overall, our results suggest that VC/PEs have value relevance in the M&A market,confirming their ‘‘certification" role. We present means for acquirers to select high-quality targets and investors to build efficient portfolios. 展开更多
关键词 M&A CERTIFICATION VC/PEs Information content
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Bioinspired Scalable Total Synthesis of Opioids
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作者 Xiaohan Zhou wenfei li +14 位作者 Ruijie Zhou Xiaoqing Wu Yuan Huang Wenlong Hou Chunxin li Yifan Zhang Wei Nie Yu Wang Hao Song Xiao-Yu liu Zhibing Zheng Fei Xie Song li Wu Zhong Yong Qin 《CCS Chemistry》 CAS 2021年第9期1376-1383,共8页
As one of the largest and most representative families of natural medicines harvested from plants,the mass production of opioids legitimately occupies large,worldwide farmland cultivation of opium poppies,causing seve... As one of the largest and most representative families of natural medicines harvested from plants,the mass production of opioids legitimately occupies large,worldwide farmland cultivation of opium poppies,causing severe regulation limitations and supply uncertainty.Due to their complex structures,the chemical synthesis of opioids has been criticized as infeasible for large-scale production in view of lengthy synthetic steps and overall low efficiency. 展开更多
关键词 natural product total synthesis OPIOID MORPHINE OXYCODONE codeine dearo matization
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