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Co@CoO催化剂表面类氢负物种NH_(2)^(δ-)驱动下的还原胺化反应
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作者 郭万君 王志强 +5 位作者 相爽 景亚轩 刘晓晖 郭勇 龚学庆 王艳芹 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2023年第4期181-190,共10页
胺类化合物作为一类重要的精细化学品,广泛应用于合成染料、表面活性剂、聚合物、药品和农用化学品.催化还原胺化是合成胺类化合物的重要手段.在还原胺化反应中,水是唯一的副产物,且反应条件温和,符合绿色化学原则,因此受到了广泛关注.... 胺类化合物作为一类重要的精细化学品,广泛应用于合成染料、表面活性剂、聚合物、药品和农用化学品.催化还原胺化是合成胺类化合物的重要手段.在还原胺化反应中,水是唯一的副产物,且反应条件温和,符合绿色化学原则,因此受到了广泛关注.在过去的几十年里,生物质衍生的羰基化合物(糠醛、环戊酮、5-羟甲基糠醛等)的催化还原胺化得到了特别关注,为利用可再生资源可持续地生产胺类提供了可能性.通常,金属(Ru,Ir,Pt,Rh,Co,Ni等)被认为是还原胺化的活性中心,相关研究快速发展,但大部分研究都围绕着金属负载型催化剂展开,对于以金属氧化物为活性中心鲜有研究.另外,还原胺化过程研究表明,席夫碱在反应开始阶段迅速生成,然后通过氨解产生相应的伯胺;但席夫碱氨解为伯胺的过程速率较慢,是该反应的决速步骤,因此设计高效催化剂加快席夫碱的氨解是还原胺化过程中的重要科学问题.受孤立的路易斯酸碱对可以催化氢气异裂过程的启发,本文利用具有核壳结构的Co@Co O为催化剂,发现表面具有氧空位的CoO具有独特的解离NH_(3)生成类氢负物种(NH_(2)^(δ-))的能力,该NH_(2)^(δ-)物种能够加速席夫碱的氨解,从而使得该催化剂展现出较好的还原胺化性能,且具有较好的稳定性,在环戊酮胺化为环戊胺过程中使用10次没有失活.通过密度泛函理论(DFT)计算和D_(2)同位素示踪实验发现了类氢负物种NH_(2)^(δ-),且验证了H^(δ-)和NH_(2)^(δ-)物种在Co O表面可稳定地共吸附,席夫碱在催化剂表面吸附较弱,使得希夫碱中间体可以在解离NH_(2)^(δ-)和H^(δ-)后的CoO表面自由移动,从而与表面解离的H^(-)和NH_(2)^(δ)–发生分子碰撞,生成伯胺,最后脱附完成催化循环.本文实现了金属氧化物催化还原胺化反应.更重要的是,在加氢/氢解反应中,孤立的路易斯酸碱对上异裂产生的H^(δ-)物种虽然具有较好的活性,但是没有H^(δ-)物种参与反应直接证据的相关报道,本研究发现的类氢负物种NH_(2)^(δ-)参与胺化反应的证据间接表明了H^(δ-)物种参与加氢/氢解反应的可能性. 展开更多
关键词 还原胺化 类氢负物种NH_(2)^(δ-) Co@CoO 席夫碱
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Catalytic conversion of lignocellulosic biomass into chemicals and fuels 被引量:6
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作者 Weiping Deng Yunchao Feng +21 位作者 Jie Fu Haiwei guo yong guo Buxing Han Zhicheng Jiang Lingzhao Kong Changzhi Li Haichao Liu Phuc T.T.Nguyen Puning Ren Feng Wang Shuai Wang Yanqin Wang Ye Wang Sie Shing Wong Kai Yan Ning Yan Xiaofei Yang Yuanbao Zhang Zhanrong Zhang Xianhai Zeng Hui Zhou 《Green Energy & Environment》 SCIE EI CSCD 2023年第1期10-114,共105页
In the search of alternative resources to make commodity chemicals and transportation fuels for a low carbon future,lignocellulosic biomass with over 180-billion-ton annual production rate has been identified as a pro... In the search of alternative resources to make commodity chemicals and transportation fuels for a low carbon future,lignocellulosic biomass with over 180-billion-ton annual production rate has been identified as a promising feedstock.This review focuses on the state-of-the-art catalytic transformation of lignocellulosic biomass into value-added chemicals and fuels.Following a brief introduction on the structure,major resources and pretreatment methods of lignocellulosic biomass,the catalytic conversion of three main components,i.e.,cellulose,hemicellulose and lignin,into various compounds are comprehensively discussed.Either in separate steps or in one-pot,cellulose and hemicellulose are hydrolyzed into sugars and upgraded into oxygen-containing chemicals such as 5-HMF,furfural,polyols,and organic acids,or even nitrogen-containing chemicals such as amino acids.On the other hand,lignin is first depolymerized into phenols,catechols,guaiacols,aldehydes and ketones,and then further transformed into hydrocarbon fuels,bioplastic precursors and bioactive compounds.The review then introduces the transformations of whole biomass via catalytic gasification,catalytic pyrolysis,as well as emerging strategies.Finally,opportunities,challenges and prospective of woody biomass valorization are highlighted. 展开更多
关键词 Lignocelullose BIOMASS Catalytic conversion Biofuels Renewable chemicals
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基于增强CT深度学习影像组学术前预测胸腺瘤风险分类
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作者 吴树剑 俞咏梅 +5 位作者 范莉芳 过永 张虎 朱浩雨 任超 徐争元 《中国肿瘤临床》 CAS CSCD 北大核心 2023年第19期999-1005,共7页
目的:探讨基于增强CT深度学习影像组学术前预测胸腺瘤风险分类的价值。方法:收集2015年1月至2023年1月皖南医学院弋矶山医院139例胸腺瘤患者为训练集,池州市人民医院与芜湖市第二人民医院81例患者为外部验证集。其中低风险组(A、AB、B1... 目的:探讨基于增强CT深度学习影像组学术前预测胸腺瘤风险分类的价值。方法:收集2015年1月至2023年1月皖南医学院弋矶山医院139例胸腺瘤患者为训练集,池州市人民医院与芜湖市第二人民医院81例患者为外部验证集。其中低风险组(A、AB、B1型)137例、高风险组(B2、B3型)83例。基于CT静脉期图像分别提取手工影像组学(hand-crafted radiomics,HCR)特征与深度学习(deep learning,DL)特征,构建影像组学标签评分(Radscore)。单因素与多因素Logistic回归分析筛选预测胸腺瘤高风险的影像学独立影响因素,利用逻辑回归(Logistic regression,LR)、随机森林(random forest,RF)、决策树(decision tree,DT)及支持向量机(support vector machine,SVM)机器学习建模。选择最佳模型为输出模型,构建模型列线图、校准曲线及临床决策曲线(decision curve analysis,DCA)。受试者工作特征(receiver operating characteristics,ROC)曲线下面积(area under the curve,AUC)及净重新分类指数(net reclassification index,NRI)用于评估模型效能。结果:LR、RF、DT及SVM构建预测模型的AUC分别为训练集0.899、0.835、0.897、0.860,外部验证集0.889、0.830、0.905、0.858。由于训练集LR模型效能最佳,作为本研究输出模型,校准曲线及DCA表明模型具有较高的校准度及临床适用性。列线图与Radscore比较效能有改善,NRI训练集为7.5%(P=0.007),外部验证集为5.3%(P=0.020)。结论:基于增强CT深度学习影像组学术前实现了胸腺瘤准确风险分类,列线图能够提供个性化预测结果。 展开更多
关键词 计算机断层扫描 深度学习 影像组学 胸腺瘤 风险分类
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Fe的原位掺杂对Pt/Silicalite-1催化丙烷脱氢反应性能的提升作用
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作者 沈姗姗 刘晓晖 +1 位作者 郭勇 王艳芹 《物理化学学报》 SCIE CAS CSCD 北大核心 2023年第7期79-88,共10页
利用一步水热法制备了原位掺杂Fe的Silicalite-1分子筛载体,浸渍得到相应的Pt基催化剂,用于丙烷的直接脱氢反应。作为对比,也制备了Pt/Silicalite-1和共浸渍的Pt1Fe2/Silicalite-1催化剂。研究发现较之Pt/Silicalite-1催化剂,原位掺入Fe... 利用一步水热法制备了原位掺杂Fe的Silicalite-1分子筛载体,浸渍得到相应的Pt基催化剂,用于丙烷的直接脱氢反应。作为对比,也制备了Pt/Silicalite-1和共浸渍的Pt1Fe2/Silicalite-1催化剂。研究发现较之Pt/Silicalite-1催化剂,原位掺入Fe的Pt/Fe-Silicalite-1催化剂反应性能有了很大程度地提高,而共浸渍制备的Pt1Fe2/Silicalite-1催化剂反应性能有所降低。在Pt/Fe-Silicalite-1催化剂上,尽管丙烷的初始转化率略有降低,但丙烯的选择性和催化稳定性大幅提高。反应8h后丙烷转化率稳定在43.7%、丙烯选择性达到98.0%;且在80h内基本保持不变。深入表征发现Fe的原位掺入使得Pt物种配位饱和度提高,避免了丙烷的深度脱氢使得丙烯选择性提高、结焦速率降低;且通过Fe-Pt之间电子转移,使得Pt上的电子云密度增强,增强了丙烯的脱附能力,进一步降低了结焦速率。另外载体中的Fe位点可以锚定Pt,使得Pt物种不易聚集,从而进一步提高了Pt/Fe-Silicalite-1的稳定性,使得该催化剂在反应80 h后仍保持高转化率和选择性。 展开更多
关键词 丙烷脱氢 SILICALITE-1 Pt基催化剂 Fe原位掺杂
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Co@CoO:An efficient catalyst for the depolymerization and upgrading of lignocellulose to alkylcyclohexanols with cellulose intact
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作者 Shuang Xiang Lin Dong +5 位作者 Zhiqiang Wang Xue Han yong guo Xiaohui Liu Xue-Qing Gong Yanqin Wang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2023年第2期191-199,I0006,共10页
The depolymerization and upgrading of lignin from raw biomass,while keeping cellulose intact is important in biorefinery and various metal-based catalysts have been used in reductive catalytic fractionation,a key meth... The depolymerization and upgrading of lignin from raw biomass,while keeping cellulose intact is important in biorefinery and various metal-based catalysts have been used in reductive catalytic fractionation,a key method in"lignin-first"strategy,Recently,we found that a core-shell structured Co@CoO catalyst with CoO shell as the real active site had excellent performance in the hydrogenolysis of 5-hydromethylfurfural to 2,5-dimethylfuran due to its unique ability to dissociate H_(2)and yield active H^(δ-)species(Xiang et al.,2022).In this work,we report a one-pot depolymerization and upgrading of lignocellulose to alkylcyclohexanols,a flavour precursor,with intact cellulose over this unique core-shell structured catalyst,Co@CoO.Lignin model compounds(β-O-4,4-O-5,α-O-4)were first used to clarify the activity of Co@CoO catalyst.Then,the one-pot conversion of various organosolv lignin(birch,pine and poplar)to alkylcyclohexanols was realized with the mass yield of alkylcyclohexanols up to25.8 wt%from birch lignin under the reaction condition of 210℃,1 MPa H_(2),16 h.Finally,the corresponding woody sawdusts were used as feedstocks and found that the Co@CoO catalyst indeed preferentially depolymerized and upgraded the lignin part and obtained the same alkylcyclohexanols products with the retention of cellulose-rich pulp.The collected alkylcyclohexanols were further esterified to obtain valueadded esters,which can be used as flavors.This work will inspire the design of new efficient metal oxide catalysts in lignin fractionation and depolymerization to high-value-added chemicals with intact cellulose. 展开更多
关键词 LIGNOCELLULOSE LIGNIN DEPOLYMERIZATION Co@CoO Alkylcyclohexanols
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Vanadium(V)reduction by using a by-product of the yellow phosphorus industry
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作者 Baibin Yang Shihong Chen +6 位作者 Haowen Ren Yang Qiu Chong Chen yong guo Chunhui Luo Qiang Zhao Wei Yang 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2023年第10期150-158,共9页
Release of vanadium(V)from industry has threatened the environment and human health.In this paper,a removal method of vanadium(V)is proposed using a by-product of the yellow phosphorus industry(phosphorus-iron)as a re... Release of vanadium(V)from industry has threatened the environment and human health.In this paper,a removal method of vanadium(V)is proposed using a by-product of the yellow phosphorus industry(phosphorus-iron)as a reducing agent.The thermodynamics analysis shows that the Gibbs free energy is always negative from 0 to 100℃,indicating a spontaneous process.Effect of the phosphorus-iron slag/sulfuric acid dosage and temperature on the removal efficiency is comprehensively studied,and the kinetics parameters are calculated based on a quasi-first order reaction kinetics model.Results indicate that vanadium(V)can be entirely reduced by using phosphorus-iron slag,the frequency factor and apparent activation energy are 3.23×10^(9)min^(-1)and 64.50 kJ.mol^(-1) for vanadium(V)reduction.Based on above results,a lab-scale reactor is constructed and achieves a removal efficiency of~100%and a treatment capacity of 200 ml vanadium(V)solution(2 g.L^(-1))within 3 h.This work demonstrates the feasibility of vanadium(V)reduction using phosphorus-iron slag as a reducing agent in applications. 展开更多
关键词 VANADIUM Phosphorus-iron slag THERMODYNAMICS KINETICS REDUCTION
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Ideal type 1 is caused by a point mutation in the a-tubulin gene that affects microtubule arrangement in soybean
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作者 Bohong Su yong guo +3 位作者 Zhongfeng Li Huawei Gao Zhongyan Wei Lijuan Qiu 《The Crop Journal》 SCIE CSCD 2023年第3期713-722,共10页
Plant architecture is a target of crop improvement.The soybean mutant ideal type 1(it1)displays a pleiotropic phenotype characterized by compact plant architecture,reduced plant height,shortened petioles,wrinkled leav... Plant architecture is a target of crop improvement.The soybean mutant ideal type 1(it1)displays a pleiotropic phenotype characterized by compact plant architecture,reduced plant height,shortened petioles,wrinkled leaves,and indented seeds.Genetic analysis revealed that the pleiotropic phenotype was controlled by an incomplete dominant gene.We characterized the cellular phenotypes of it1 and positionally cloned the it1 locus.Detailed morphogenetic analysis of the it1 mutant revealed an excess of xylem cells and expanded phloem,and polygonal pavement cells.Positional cloning showed that the phenotype was caused by a G-to-A mutation in the second exon of the a-tubulin gene(Glyma.05G157300).The mutation altered microtubule arrangement in pavement cells,changing their morphology.Overexpression of Gmit1 resulted in an it1-like phenotype and polygonal pavement cells and microtubules of overexpressors were parallel or slightly inclined.Five suppressor mutants able to suppress the phenotype of it1 were obtained by EMS mutagenesis in the it1 background.All these mutants carried an additional mutation in the it1 gene.These results suggest that the pleiotropic phenotype of it1 is caused by the mutation in the atubulin gene. 展开更多
关键词 SOYBEAN Plant architecture a-Tubulin MICROTUBULES Intragenic mutations
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Pressure-induced growth of coralloid-like FeF_(2) nanocrystals to enable high-performance conversion cathode
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作者 Yulin Xu Wenjing Xiong +6 位作者 Jiaqi Huang Xinglin Tang Hongqiang Wang Wei Liu Dan Xiao yong guo yongzhi Zhang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2023年第4期291-300,共10页
Fluoride ferrous(FeF_(2))is viewed as a promising conversion cathode material for next-generation lithiumion batteries(LIBs)due to its high theoretical specific capacity and low cost.Unfortunately,issues such as poor ... Fluoride ferrous(FeF_(2))is viewed as a promising conversion cathode material for next-generation lithiumion batteries(LIBs)due to its high theoretical specific capacity and low cost.Unfortunately,issues such as poor intrinsic conductivity,iron dissolution,and phase separation hinder the application of FeF_(2)in highenergy cathodes.Here,a pressure-induced morphology control method is designed to prepare coralloidlike FeF_(2)nanocrystals with nitrogen-rich carbon coating(c-FeF_(2)@NC).The coralloid-like interconnected crystal structure of c-FeF_(2)@NC contributes to reducing interfacial resistance and enhancing the topotactic transformation during the conversion reaction,and the nitrogen-rich carbon(NC)coating can enhance interfacial stability and kinetic performance.When used as a conversion cathode for LIBs,c-FeF_(2)@NC exhibits a high initial reversible capacity of 503.57 mA h g^(-1)and excellent cycling stability of497.61 m A h g^(-1)with a low capacity decay of 1.19%over 50 cycles at 0.1 A/g.Even at 1 A/g,a stable capacity of 263.78 mA h g^(-1)can still be retained after 200 cycles.The capability of c-FeF_(2)@NC as a conversion cathode for sodium-ion batteries(SIBs)was also evaluated to expand its field of application.Furthermore,two kinds of full batteries have been assembled by employing c-FeF_(2)@NC as cathodes and quantitative limited-Li(LLi)and pre-lithiated reduced graphene oxide(PGO)as anodes,respectively,to envisage the feasibility of practical applications of conversion materials. 展开更多
关键词 Conversion cathode Carbon coating Coralloid-like FeF_(2) Pressure-induced growth
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Duality of Li_(2)CO_(3) in Solid-State Batteries
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作者 Xuerui Yi yong guo +4 位作者 Siyuan Pan Yiqiao Wang Sijia Chi Shichao Wu Quan-Hong Yang 《Transactions of Tianjin University》 EI CAS 2023年第1期73-86,共14页
Solid-state batteries(SSBs)have been considered the most promising technology because of their superior energy density and safety.Among all the solid-state electrolytes(SEs),Li_(7) La_(3) Zr_(2) O_(12)(LLZO)with high ... Solid-state batteries(SSBs)have been considered the most promising technology because of their superior energy density and safety.Among all the solid-state electrolytes(SEs),Li_(7) La_(3) Zr_(2) O_(12)(LLZO)with high ionic conductivity(3×10^(−4) S/cm)has been widely investigated.However,its large-scale production in ambient air faces a challenge.After air exposure,the generated Li_(2)CO_(3) layer deteriorates the ionic conductivity and interfacial wettability,thus greatly compromising the electrochemical performance of SSBs.Many works aim to eliminate this layer to recover the pristine LLZO surface.Unfor-tunately,few articles have emphasized the merits of Li_(2)CO_(3).In this review,we focus on the two-sidedness of Li_(2)CO_(3).We discuss the various characteristics of Li_(2)CO_(3) that can be used and recapitulate the strategies that utilize Li_(2)CO_(3).Insulating Li_(2)CO_(3) is no longer an obstacle but an opportunity for realizing intimate interfacial contact,high air stability,and outstand-ing electrochemical performance.This review aims to off er insightful guidelines for treating air-induced Li_(2)CO_(3) and lead to developing the enhanced air stability and electrochemical performance of LLZO. 展开更多
关键词 Solid-state battery GARNET Li_(7)La_(3)Zr_(2)O_(12) Li_(2)CO_(3)
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昆明市安宁市社区轻度认知障碍的患病率及影响因素研究
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作者 刘瑞 郭玲 +8 位作者 俞春雷 秦正宇 吴渔燕 王睿 李国 于学军 姚俊凤 郭永 郑永珍 《阿尔茨海默病及相关病杂志》 2023年第1期15-19,共5页
目的:了解昆明市安宁市社区65岁及以上老年人轻度认知功能障碍(mild cognitive impairment,MCI)的患病现状及其影响因素,为认知障碍的早期预防提供参考依据。方法:采用随机整群抽样的方法,随机抽取621名2021年7月至昆明市安宁市第一人... 目的:了解昆明市安宁市社区65岁及以上老年人轻度认知功能障碍(mild cognitive impairment,MCI)的患病现状及其影响因素,为认知障碍的早期预防提供参考依据。方法:采用随机整群抽样的方法,随机抽取621名2021年7月至昆明市安宁市第一人民医院金方院区健康管理中心体检的三个社区进行认知功能障碍调查,参与调查人员均为65岁及以上老年人,采用单因素和多因素二元Logistic回归多因素分析患MCI的影响因素。结果:昆明市安宁市社区≥65岁的老年人MCI患病率为9.7%,低于我国近年来城市老年人患MCI的平均水平;年龄、婚姻、文化程度、高血压、糖尿病、脑梗死、铜均影响MCI患病率,其中,高教育程度和高血压是MCI的危险因素。结论:昆明市安宁市社区65岁及以上老年人MCI患病率偏低,建议早筛查、早干预,控制MCI危险因素,以延缓痴呆发病。 展开更多
关键词 老年人 轻度认知障碍 患病率 影响因素
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一种基于电沉积3D花状CoS在自支撑石墨烯胶带电极上的非酶葡萄糖传感器的研究与应用 被引量:1
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作者 李江 李作鹏 +6 位作者 白云峰 罗宿星 郭永 鲍雅妍 李容 刘海燕 冯锋 《电化学》 CAS CSCD 北大核心 2022年第1期65-75,共11页
本文将3D纳米结构花状CoS电沉积在石墨烯胶带电极(GTE)上,制备了一种对葡萄糖响应良好的电化学传感器。结构分析显示电沉积的CoS均匀地分散在了电极上。实验结果表明,制备的花状CoS/GTE葡萄糖传感器在0.025~1.0 mmol·L^(-1)显示出... 本文将3D纳米结构花状CoS电沉积在石墨烯胶带电极(GTE)上,制备了一种对葡萄糖响应良好的电化学传感器。结构分析显示电沉积的CoS均匀地分散在了电极上。实验结果表明,制备的花状CoS/GTE葡萄糖传感器在0.025~1.0 mmol·L^(-1)显示出良好的线性关系,灵敏度为323.3μA·(mmol·L^(-1))^(-1)·cm^(-2),检出限为8.5μmol·L^(-1)(S/N=3),而且制备的传感器能够应用于血清葡萄糖的检测。这表明本文制备的传感器具有一定的应用潜力。 展开更多
关键词 柔性电极 花状CoS 电沉积 葡萄糖传感器
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木质素在不同Ru/Nb基催化剂上解聚和脱氧加氢制芳烃化合物(英文) 被引量:5
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作者 马迪 陆圣璐 +2 位作者 刘晓晖 郭勇 王艳芹 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2019年第4期609-617,M0006,共10页
木质素高效转化为芳烃是木质素利用的一个非常重要的过程,一般通过解聚和脱氧加氢反应来实现.我们曾发现NbOx物种在木质素及其模型化合物的C–O键活化和断裂的过程中发挥了至关重要的作用.本文分别选择两种商业的铌基材料(HY-340和NbPO-... 木质素高效转化为芳烃是木质素利用的一个非常重要的过程,一般通过解聚和脱氧加氢反应来实现.我们曾发现NbOx物种在木质素及其模型化合物的C–O键活化和断裂的过程中发挥了至关重要的作用.本文分别选择两种商业的铌基材料(HY-340和NbPO-CBMM)和实验室自制的具有层状结构的氧化铌材料(Nb_2O_5-Layer)为载体,制备了负载型Ru催化剂,将其用于木质素及其模型化合物的催化转化.同时,为了尽量避免Ru与铌基载体相互作用的影响,制备了较为均匀的Ru纳米胶粒并吸附于铌基载体上,得到Ru@铌基催化剂,并用于木质素模型化合物—对甲酚的催化转化反应中.研究表明,木质素在所有的Ru/铌基催化剂上都可以得到比较高的C7–C9碳氢化合物的收率.其中,在Ru/Nb_2O_5-Layer催化剂上C_7–C_9碳氢化合物的摩尔收率为99.1%,选择性为88.0%.采用X射线衍射、N_2吸附-脱附、热重分析、吡啶吸附红外光谱(Py-FTIR)、X射线光电子能谱(XPS)以及CO化学吸附等技术表征了Ru/铌基催化剂的性能与铌基材料的性质、金属Ru颗粒大小及其表面电子状态之间的关系.Py-FTIR结果表明, Nb_2O_5-Layer材料上几乎没有Br?nsted酸,但含有最多的Lewis酸,而NbPO-CBMM上的Lewis酸量最低.结合催化性能数据发现,单体产物收率与铌基载体的Lewis量成正相关关系,其中以Ru/Nb_2O_5-Layer催化剂上最高.CO化学吸附和XPS结果表明,不同的铌基载体负载的金属Ru的分散度和电子状态都有差异.在Ru/Nb_2O_5-Layer上Ru的分散度最好,颗粒尺寸最小,木质素转化得到的芳烃选择性最好;在Ru/HY-340和Ru/NbPO-CBMM上,虽然Ru的分散度相近,但其表面电子状态不同, Ru/HY-340上的金属态Ru带有更多的正电荷δ+,其得到芳烃的选择性高于Ru/Nb PO-CBMM.由此可见, Ru的颗粒尺寸和表面电子状态会影响芳烃选择性.对甲酚催化转化反应结果表明, Ru颗粒大小相同时,铌基载体性质会影响对甲酚转化率;而同一铌基载体上, Ru颗粒大小则影响芳烃选择性,较小的Ru颗粒有利于芳烃的生成. 展开更多
关键词 木质素 芳烃化合物 铌基载体 路易斯酸
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低成本合成纳米堆积的SAPO-34分子筛及其在糠醇催化醇解反应中的应用 被引量:3
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作者 郭倩倩 杨帆 +3 位作者 刘晓晖 孙孟清 郭勇 王艳芹 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2020年第11期1772-1781,共10页
SAPO-34分子筛因其规则的孔结构、独特的择形性和适宜的酸性,在石油化工领域有着重要的应用.本文不添加四乙基氢氧化铵(TEAOH)之外的模板剂,仅改变原料的加入顺序,通过水热合成法制备了两种不同形貌的SAPO-34分子筛(纳米堆积SAPO-34和... SAPO-34分子筛因其规则的孔结构、独特的择形性和适宜的酸性,在石油化工领域有着重要的应用.本文不添加四乙基氢氧化铵(TEAOH)之外的模板剂,仅改变原料的加入顺序,通过水热合成法制备了两种不同形貌的SAPO-34分子筛(纳米堆积SAPO-34和立方体SAPO-34).结果表明,前驱体的存在形式和成核速率是导致形貌不同的主要原因.拟薄水铝石和正硅酸乙酯在碱性条件下水解,铝和硅的前驱体分别以Al(OH)4-和SiO2(OH)-的形式存在,二者相互结合生成分子筛生长的基本单元:具有Si–O–Al键的硅铝酸化合物,它们倾向于形成更多的如低聚物、非晶态颗粒或纳米晶等的二级单元,这些二级单元均有利于晶核的快速生成,并在范德华力的作用下进行自组装,形成聚集体堆积的球形纳米晶,纳米晶继续长大,最终生成了结晶度较高的纳米聚集体SAPO-34.而在酸性体系中,铝和硅的前驱体分别以Al3+和(OH)3Si(OH2)+的形式存在,TEAOH加入后,铝会在硅表面沉积,从而显著减慢Si–O–Si键的断裂,使得晶核生成的速度减慢,最终通过一层一层生长的机制进行晶体生长而形成较大的立方体SAPO-34.为了进一步探讨形貌结构对SAPO-34分子筛酸催化性能的影响,我们选择分子尺寸略大于传统SAPO-34孔道尺寸(约0.38 nm)的生物质基糠醇(FAL,约0.53 nm)为模型反应物,分别研究了纳米堆积SAPO-34和立方体SAPO-34分子筛在糠醇醇解制备乙酰丙酸乙酯(EL)反应中的催化性能.与传统的立方体SAPO-34相比,纳米堆积SAPO-34分子筛由于纳米晶的堆积具有较大的外比表面积和堆积介孔孔容,从而具有更多的外表面酸性,因此在糠醇醇解反应中表现出更高的EL收率(74.1%),而立方SAPO-34仅有19.9%的EL收率.此外,纳米堆积SAPO-34分子筛也因其具有较大的外比表面和堆积介孔孔容,利于反应过程中乙氧基甲基呋喃中间体、产物及副产物的传质,减少了碳的沉积,从而改善了其稳定性. 展开更多
关键词 纳米堆积SAPO-34 外比表面 低成本 催化醇解 糠醇
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氧化铌高效催化生物质衍生物的羟醛缩合反应制备燃料前驱体(英文) 被引量:3
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作者 景亚轩 辛宇 +2 位作者 郭勇 刘晓晖 王艳芹 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2019年第8期1168-1177,共10页
生物质是自然界唯一可再生的有机碳来源,其催化转化制备燃料和精细化学品受到广泛关注.一般从生物质衍生的小分子出发制备航空煤油和柴油等高碳数燃料包括两步:首先通过碳链增长反应如羟醛缩合和烷基化等制备目标链结构的燃料前驱体,然... 生物质是自然界唯一可再生的有机碳来源,其催化转化制备燃料和精细化学品受到广泛关注.一般从生物质衍生的小分子出发制备航空煤油和柴油等高碳数燃料包括两步:首先通过碳链增长反应如羟醛缩合和烷基化等制备目标链结构的燃料前驱体,然后对所得燃料前驱体进行完全脱氧加氢得到燃料组分.在目前报道的碳链增长反应中,羟醛缩合反应应用最多,因为生物质衍生的羰基化合物众多,而且丙酮、糠醛及环己酮等羰基化合物已经实现了工业化生产.羟醛缩合反应的催化剂以碱性材料为主,但是碱性催化剂具有不抗二氧化碳、不抗水等缺点,因此开发高活性的固体酸催化剂至关重要.本文选择糠醛和4-庚酮的羟醛缩合反应作为模型反应,发现氧化铌材料对该反应具有优异的催化活性,活性明显高于常见的氧化钙、氧化镁、镁铝水滑石等固体碱和氧化铝、氧化锆等固体酸.并采用N2吸附-脱附、二氧化碳程序升温脱附(CO-TPD)、吡啶吸附红外光谱(Py-FTIR)、程序升温氨脱附(NH3-TPD)和丙酮的原位吸附傅立叶变换红外光谱等表征手段研究了氧化铝,氧化锆和氧化铌催化性能差异的原因.结果表明,这三种催化剂的比表面积和酸性质与反应活性没有明显关联.为了解释反应活性的差异,我们采用丙酮原位吸附红外光谱探究了这三种催化剂对羰基的活化.发现相比于氧化铝和氧化锆催化剂,氧化铌对丙酮的C=O双键有更强的活化能力,使C=O双键结构更容易转化为烯醇式结构,进而促进羟醛缩合反应的进行.基于此,我们提出了氧化铌催化羟醛缩合的反应机理.另外,底物拓展实验发现,在其他生物质相关的羟醛缩合反应体系中,氧化铌催化依旧可以得到可观的收率.循环套用实验表明,由于积碳导致催化剂失活,通过简单的煅烧即可恢复活性.我们之前的研究发现负载金属的铌基催化剂具有很好的断裂呋喃环上碳氧键的能力,是很好的脱氧加氢催化剂.基于以上研究和我们之前的结论,我们设计并制备了多功能的Pd/Nb2O5催化剂,对该催化剂进行了结构表征,并对羟醛缩合和脱氧加氢过程进行了设计整合,一锅实现了羟醛缩合和后续的脱氧加氢. 展开更多
关键词 羟醛缩合 氧化铌 C=O活化 燃料前驱体 生物燃料 一锅过程
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抗氧化剂在猪精液冷冻保存中的作用 被引量:4
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作者 康乐毅 赵俊金 +6 位作者 邓晓彬 程晨 刘刚 张永红 郭勇 邢凯 倪和民 《猪业科学》 2020年第10期44-47,共4页
随着冷冻精液技术的发展,抗氧化剂作为精液稀释液中必不可少的一类成分,在降低精子的氧化损伤、提高精子活力质量上起到了关键的作用。文章对近些年来国内科研团队所使用的抗氧化剂进行综述,总结其对精液品质提升改善的能力,为猪精液冷... 随着冷冻精液技术的发展,抗氧化剂作为精液稀释液中必不可少的一类成分,在降低精子的氧化损伤、提高精子活力质量上起到了关键的作用。文章对近些年来国内科研团队所使用的抗氧化剂进行综述,总结其对精液品质提升改善的能力,为猪精液冷冻技术的发展提供理论依据和参考。 展开更多
关键词 抗氧化剂 冷冻精液 研究进展
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Ssc-miR-133a-5p的靶基因预测及其相关信号通路的生物信息学分析 被引量:1
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作者 常雪蕊 赵志显 +7 位作者 赵俊金 邓晓彬 刘刚 张永红 郭勇 倪和民 王楚端 邢凯 《猪业科学》 2020年第12期102-105,共4页
课题组前期通过高通量测序技术发现,microRNAssc-miR-133a-5p在肥胖猪脂肪组织中表达水平显著下调,推测其可能在脂肪沉积过程中发挥了重要作用。分析ssc-miR-133a-5p序列保守性,利用TargetScan,miRDB和miRWalk在线分析工具预测其候选靶... 课题组前期通过高通量测序技术发现,microRNAssc-miR-133a-5p在肥胖猪脂肪组织中表达水平显著下调,推测其可能在脂肪沉积过程中发挥了重要作用。分析ssc-miR-133a-5p序列保守性,利用TargetScan,miRDB和miRWalk在线分析工具预测其候选靶基因,进一步对候选靶基因进行蛋白质互作分析以及KEGG分析,最后将预测的靶基因与课题组前期筛选出的与猪脂肪沉积能力相关的基因取交集。结果表明ssc-miR-133a-5p候选靶基因PPARGC1A与RORA等,参与AMPK,TNF,与胰岛素分泌等信号通路。结果提示ssc-miR-133a-5p的候选靶基因可能通过多种信号通路发挥重要作用。文章的结果可为microRNA参与猪的脂肪生成调节机制提供科学依据。 展开更多
关键词 ssc-miR-133a-5p 靶基因预测 信号通路
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母猪批次化生产猪场的各类猪群存栏数及占栏数的计算 被引量:1
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作者 邢凯 张永红 +5 位作者 郭勇 陈少康 薛振华 李爽 王楚端 倪和民 《猪业科学》 2020年第9期108-110,共3页
合理的猪群结构、猪群组成及其周转是猪场均衡生产和提高效率的关键因素。目前,母猪批次化生产技术在猪场实施的过程中,各种参数的制定、各类猪群存栏数及占栏数的计算依据不清晰,容易出现错误。文中的研究以600头基础母猪、7 d为一个... 合理的猪群结构、猪群组成及其周转是猪场均衡生产和提高效率的关键因素。目前,母猪批次化生产技术在猪场实施的过程中,各种参数的制定、各类猪群存栏数及占栏数的计算依据不清晰,容易出现错误。文中的研究以600头基础母猪、7 d为一个生产周期猪场为例,详细地阐述了生产参数的制定、不同猪群的存栏数和占栏数的计算依据和过程,以期为猪场设计人员的猪场设计与建设和养猪生产者生产工艺的制定提供参考。 展开更多
关键词 批次化生产 存栏 参数
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N-doped porous carbon nanofibers sheathed pumpkin-like Si/C composites as free-standing anodes for lithium-ion batteries 被引量:6
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作者 Yanfei Zeng Yudai Huang +7 位作者 Niantao Liu Xingchao Wang Yue Zhang yong guo Hong-Hui Wu Huixin Chen Xincun Tang Qiaobao Zhang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2021年第3期727-735,共9页
Dramatic capacity fading and poor rate performance are two main obstacles that severely hamper the widespread application of the Si anode owing to its large volume variation during cycling and low intrinsic electrical... Dramatic capacity fading and poor rate performance are two main obstacles that severely hamper the widespread application of the Si anode owing to its large volume variation during cycling and low intrinsic electrical conductivity.To mitigate these issues,free-standing N-doped porous carbon nanofibers sheathed pumpkin-like Si/C composites(Si/C-ZIF-8/CNFs)are designed and synthesized by electrospinning and carbonization methods,which present greatly enhanced electrochemical properties for lithium-ion battery anodes.This particular structure alleviates the volume variation,promotes the formation of stable solid electrolyte interphase(SEI)film,and improves the electrical conductivity.As a result,the as-obtained free-standing Si/C-ZIF-8/CNFs electrode delivers a high reversible capacity of 945.5 mAh g^(-1) at 0.2 A g^(-1) with a capacity retention of 64% for 150 cycles,and exhibits a reversible capacity of 538.6 mA h g^(-1) at 0.5 A g^(-1) over 500 cycles.Moreover,the full cell composed of a freestanding Si/C-ZIF-8/CNFs anode and commercial LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)(NCM)cathode shows a capacity of 63.4 mA h g^(-1) after 100 cycles at 0.2 C,which corresponds to a capacity retention of 60%.This rational design could provide a new path for the development of high-performance Si-based anodes. 展开更多
关键词 Pumpkin-like silicon/carbon composites N-doped porous carbon nanofibers Free-standing anode Lithium-ion batteries
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Differentiation of human adipose-derived stem cells into neuron-like cells by Radix Angelicae Sinensis 被引量:3
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作者 Qiaozhi Wang Lile Zhou +3 位作者 yong guo Guangyi Liu Jiyan Cheng Hong Yu 《Neural Regeneration Research》 SCIE CAS CSCD 2013年第35期3353-3358,共6页
Human adipose tissues are an ideal source of stem cells.It is important to find inducers that can safely and effectively differentiate stem cells into functional neurons for clinical use.In this study,we investigate t... Human adipose tissues are an ideal source of stem cells.It is important to find inducers that can safely and effectively differentiate stem cells into functional neurons for clinical use.In this study,we investigate the use of Radix Angelicae Sinensis as an inducer of neuronal differentiation.Primary human adipose-derived stem cells were obtained from adult subcutaneous fatty tissue,then pre-induced with 10%Radix Angelicae Sinensis injection for 24 hours,and incubated in serum-free Dulbecco’s modified Eagle’s medium/Nutrient Mixture F-12 containing 40%Radix Angelicae Sinensis to induce its differentiation into neuron-like cells.Butylated hydroxyanisole,a common inducer for neuronal differentiation,was used as the control.After human adipose-derived stem cells differentiated into neuron-like cells under the induction of Radix Angelicae Sinensis for 24 hours,the positive expression of neuron-specific enolase was lower than that of the butylated hydroxyanisole-induced group,and the expression of glial fibrillary acidic protein was negative.After they were induced for 48 hours,the positive expression of neuron specific enolase in human adipose-derived stem cells was significantly higher than that of the butylated hydroxyanisole-induced group.Our experimental findings indicate that Radix Angelicae Sinensis can induce human adipose-derived stem cell differentiation into neuron-like cells and produce less cytotoxicity. 展开更多
关键词 神经元样细胞 脂肪干细胞 细胞分化 脂肪来源 神经元特异性烯醇化酶 冬虫夏草 丁基羟基茴香醚 板蓝根
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Use of ^(18)F-FDG PET/CT to locate primary malignancies in patients with hepatic cirrhosis and malignant ascites 被引量:3
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作者 He-Bin Fan Ai-Jun Wang +9 位作者 Dong-Liang Yang Jun Xiao Yun Ai Lu Huang yong guo Mu-Xiu Zhou Juan-Juan Wu Zhi Li Fu-Ming Yan Yi-Ming Wang 《Chinese Journal of Cancer Research》 SCIE CAS CSCD 2013年第5期500-504,共5页
Objective:Ascites in patients with hepatic cirrhosis is caused by cirrhosis in most cases.For most malignant ascites,the primary malignancy could be readily identified using conventional imaging methods,e.g.,computer ... Objective:Ascites in patients with hepatic cirrhosis is caused by cirrhosis in most cases.For most malignant ascites,the primary malignancy could be readily identified using conventional imaging methods,e.g.,computer tomography(CT)and magnetic resonance imaging(MRI).However,in a small fraction of the patients,the primary malignancy remains occult even with these examinations.In this retrospective study,we assessed the usefulness of18F-FDG PET/CT in patients with hepatic cirrhosis and malignant ascites of otherwise unknown origin.Methods:Twenty-eight patients with malignant ascites of unknown primary sites after CT,MRI and ultrasound during the period of five years between January 2008 and December 2012 had received18F-FDG PET/CT.Medical records of these patients were reviewed and analyzed.Results:Elevated18F-FDG absorption was found in 23 of 28 cases in the following sites:gastrointestinal tract(n=10,43.5%),prostate(n=5,21.7%),peritoneum(n=4,13.3%),and ovary(n=4,13.3%).Cancer was confirmed by pathology in 20 cases after open or laparoscopic surgeries.Five patients were found to have benign ascites,among which,3 were found to be false positive due to tuberculosis.SUV values were significantly higher for tumors than for benign lesions(mean values,6.95 vs.2.94;P=0.005).Conclusions:The18F-FDG PET/CT can be as a powerful imaging tool in identifying tissue origin in liver cirrhosis patients suspected of cancers or with cancers of unknown primary sites. 展开更多
关键词 肿瘤患者 恶性肿瘤 肝硬化 PET 腹水 CT 计算机断层扫描 定位
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