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Nickel single atom overcoordinated active sites to accelerate the electrochemical reaction kinetics for Li-S cathode 被引量:2
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作者 Juan Zhu Xinyue Wang +13 位作者 Tian Ke Mingji Jia Biyu Jin Yuanyuan Li Qiwei Yang Lanhui Ren Yongyuan Ren Dangguo Cheng Jianguo Lu Xiang Gao Qinggang He Yang Hou Xiaoli Zhan Qinghua Zhang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2023年第3期203-210,I0006,共9页
Lithium-sulfur(Li-S)batteries with high theoretical energy density are promising advanced energy storage devices.However,shuttling of dissolute lithium polysulfide(LiPSs)and sluggish conversion kinetics impede their a... Lithium-sulfur(Li-S)batteries with high theoretical energy density are promising advanced energy storage devices.However,shuttling of dissolute lithium polysulfide(LiPSs)and sluggish conversion kinetics impede their applications.Herein,single nickel(Ni)atoms on two-dimensional(2D)nitrogen(N)-doped carbon with Ni-N_(4)-O overcoordinated structure(SANi-N_(4)-O/NC)are prepared and firstly used as a sulfur host of Li-S batteries.Due to the efficient polysulfides traps and highly LiPSs conversion effect of SANi-N_(4)-O/NC,the electrochemical performance of Li-S batteries obviously improved.The batteries can well operate even under high sulfur loading(5.8 mg cm^(-2))and lean electrolyte(6.1μL mg^(-1))condition.Meanwhile,density functional theory(DFT)calculations demonstrate that Ni single atom’s active sites decrease the energy barriers of conversion reactions from Li_(2)S_(8)to Li2S due to the strong interaction between SANi-N_(4)-O/NC and LiPSs.Thus,the kinetic conversion of LiPSs was accelerated and the shuttle effect is suppressed on SANi-N_(4)-O/NC host.This study provides a new design strategy for a 2D structure with single-atom overcoordinated active sites to facilitate the fast kinetic conversion of LiPSs for Li-S cathode. 展开更多
关键词 Nickel single atom catalyst Ni-N_(4)-O sites 2D N-doped carbon Li-S batteries Shuttle effect
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The Active Sites of the Reference Phase of SmVO_4 as Catalyst for Propane Oxidative Dehydrogenation 被引量:1
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作者 ZHANG Wei-de AU Chak-tong +1 位作者 LI Ji-tao WAN Hui-lin 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 1998年第3期72-74,共3页
IntroductionTheutilizationofalkanetoproduceintermediatechemicalsisalwaysatractive.Thefunctionalizationofligh... IntroductionTheutilizationofalkanetoproduceintermediatechemicalsisalwaysatractive.Thefunctionalizationoflightparafinbycatalyt... 展开更多
关键词 Samarium orthovanadate Active site V 4+ species Oxidative dehydrogenation
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Single-Atom Pd–N_(3)Sites on Carbon-Defi cient g-C_(3)N_(4)for Photocatalytic H_(2)Evolution 被引量:3
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作者 Guimei Liu Haiqin Lv +4 位作者 Yubin Zeng Mingzhe Yuan Qingguo Meng Yuanhao Wang Chuanyi Wang 《Transactions of Tianjin University》 EI CAS 2021年第2期139-146,共8页
Photocatalytic hydrogen evolution is an attractive fi eld for future environment-friendly energy.However,fast recombination of photogenerated charges severely inhibits hydrogen effi ciency.Single-atom cocatalysts such... Photocatalytic hydrogen evolution is an attractive fi eld for future environment-friendly energy.However,fast recombination of photogenerated charges severely inhibits hydrogen effi ciency.Single-atom cocatalysts such as Pt have emerged as an eff ective method to enhance the photocatalytic activity by introduction of active sites and boosting charge separation with low-coordination environment.Herein,we demonstrated a new strategy to develop a highly active Pd single atom in carbondefi cient g-C_(3)N_(4)with a unique coordination.The single-atom Pd–N_(3)sites constructed by oil bath heating and photoreduction process were confi rmed by HADDF-STEM and XPS measurements.Introduction of single-atom Pd greatly improved the separation and transportation of charge carriers,leading to a longer lifespan for consequent reactions.The obtained singleatom Pd loaded on the carbon-defi cient g-C_(3)N_(4)showed excellent photocatalytic activity in hydrogen production with about 24 and 4 times higher activity than that of g-C_(3)N_(4)and nano-sized Pd on the same support,respectively.This work provides a new insight on the design of single-atom catalyst. 展开更多
关键词 SINGLE-ATOM PD g-C_(3)N_(4) Active sites HYDROGEN PHOTOCATALYTIC
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A Universal Principle to Accurately Synthesize Atomically Dispersed Metal–N_4 Sites for CO_2 Electroreduction 被引量:3
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作者 Wanzhen Zheng Feng Chen +7 位作者 Qi Zeng Zhongjian Li Bin Yang Lecheng Lei Qinghua Zhang Feng He Xilin Wu Yang Hou 《Nano-Micro Letters》 SCIE EI CAS CSCD 2020年第9期14-25,共12页
Atomically dispersed metal-nitrogen sites-anchored carbon materials have been developed as effective catalysts for CO2 electroreduction(CO2 ER),but they still suffer from the imprecisely control of type and coordinati... Atomically dispersed metal-nitrogen sites-anchored carbon materials have been developed as effective catalysts for CO2 electroreduction(CO2 ER),but they still suffer from the imprecisely control of type and coordination number of N atoms bonded with central metal.Herein,we develop a family of single metal atom bonded by N atoms anchored on carbons(SAs-M-N-C,M=Fe,Co,Ni,Cu)for CO2 ER,which composed of accurate pyrrole-type M-N4 structures with isolated metal atom coordinated by four pyrrolic N atoms.Benefitting from atomically coordinated environment and specific selectivity of M-N4 centers,SAs-Ni-N-C exhibits superior CO2 ER performance with onset potential of-0.3 V,CO Faradaic efficiency(F.E.) of 98.5%at-0.7 V,along with low Tafel slope of 115 mV dec-1 and superior stability of 50 h,exceeding all the previously reported M-N-C electrocatalysts for CO2-to-CO conversion.Experimental results manifest that the different intrinsic activities of M-N4 structures in SAs-M-N-C result in the corresponding sequence of Ni> Fe> Cu> Co for CO2 ER performance.An integrated Zn-CO2 battery with Zn foil and SAs-Ni-N-C is constructed to simultaneously achieve CO2-to-CO conversion and electric energy output,which delivers a peak power density of 1.4 mW cm-2 and maximum CO F.E.of 93.3%. 展开更多
关键词 Atomic dispersion Pyrrole-type metal–N4 structure Catalytic site CO2 electroreduction Zn–CO2 battery
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Accurate design of spatially separated double active site in Bi_(4)NbO_(8)Cl single crystal to promote Z-Scheme photocatalytic overall water splitting
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作者 Kailong Gao Hongxia Guo +4 位作者 Yanan Hu Hongbin He Mowen Li Xiaoming Gao Feng Fu 《Journal of Energy Chemistry》 SCIE EI CSCD 2023年第12期568-582,I0014,共16页
The efficiency of photocatalytic overall water splitting was mainly limited by the slow reaction kinetics of water oxidation.How to design effective surface active site to overcome the slow water oxidation reaction wa... The efficiency of photocatalytic overall water splitting was mainly limited by the slow reaction kinetics of water oxidation.How to design effective surface active site to overcome the slow water oxidation reaction was a major challenge.Here,we propose a strategy to accelerate surface water oxidation through the fabrication spatially separated double active sites.FeCoPi/Bi_(4)NbO_(8)Cl-OVs photocatalyst with spatially separated double active site was prepared by hydrogen reduction photoanode deposition method.Due to the high matching of the spatial loading positions of FeCoPi and OVs with the photogenerated charge distribution of Bi_(4)NbO_(8)Cl and corresponding reaction mechanisms of substrate,the FeCoPi and OVs on the(001)and(010)crystal planes of Bi_(4)NbO_(8)Cl photocatalyst provided surface active site for water oxidation reaction and electron shuttle reaction(Fe^(3+)/Fe^(2+)),respectively.Under visible light irradiation,the evolution O_(2)rate of FeCoPi/Bi_(4)NbO_(8)Cl OVs was 16.8μmol h^(-1),as 32.9 times as Bi_(4)NbO_(8)Cl.Furthermore,a hydrogen evolution co-catalyst PtRu@Cr_(2)O_(3)was prepared by sequential photodeposition method.Due to the introduction of Ru,the Schottky barrier between PbTiO_(3)and Pt was effectively reduced,which promoted the transfer of photogenerated electrons to PtRu@Cr_(2)O_(3)thermodynamically,the evolution H_(2)rate on PtRu@Cr_(2)O_(3)/PbTiO_(3)increased to 664.8 times.On based of the synchronous enhancement of the water oxidation performance on FeCoPi/Bi_(4)NbO_(8)Cl-OVs and water reduction performance on PtRu@Cr_(2)O_(3)/PbTiO_(3),a novel Z-Scheme photocatalytic overall water splitting system(FeCoPi/Bi_(4)NbO_(8)Cl-OVs)mediated by Fe^(3+)/Fe^(2+)had successfully constructed.Under visible light irradiation,the evolution rates of H_(2)and O_(2)were 2.5 and 1.3μmol h^(-1),respectively.This work can provide some reference for the design of active site and the controllable synthesis of OVs spatial position.On the other hand,the hydrogen evolution co catalyst(PtRu@Cr_(2)O_(3))and the co catalyst FeCoPi for oxygen evolution contributed to the construction of an overall water splitting system. 展开更多
关键词 Spatially separated double active sites FeCoPi/Bi_(4)NbO_(8)Cl-OVs Photocatalytic water oxidation Photocatalytic hydrogen evolution Hydrogen evolution co-catalyst PtRu@Cr_(2)O_(3) Z-Scheme photocatalytic overall water splitting system
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氢化增强暴露{111}晶面NiFe_(2)O_(4)八面体的气体传感性能及其传感机理
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作者 孟小华 李玉红 杨合情 《材料科学与工程学报》 CAS CSCD 北大核心 2023年第1期58-64,共7页
以六水合氯化铁、六水合氯化镍、氢氧化钠和乙二醇为原料,在200℃下水热合成10 h,制得暴露{111}晶面的NiFe_(2)O_(4)八面体。将该产物用于甲醇和三乙胺的传感反应中均表现出良好的气敏活性。通过加氢去除表面的—OH和Cl-离子后,其气体... 以六水合氯化铁、六水合氯化镍、氢氧化钠和乙二醇为原料,在200℃下水热合成10 h,制得暴露{111}晶面的NiFe_(2)O_(4)八面体。将该产物用于甲醇和三乙胺的传感反应中均表现出良好的气敏活性。通过加氢去除表面的—OH和Cl-离子后,其气体传感性能得到进一步提高。传感性能的增强是由于表面Cl-离子和—OH基团的去除,导致NiFe_(2)O_(4)表面3配位不饱和Fe原子数量增加。以不饱和金属原子作为传感反应的活性位点,提出了一种原子和分子水平的气体传感机制。此传感机制对于设计和制备先进的气体传感器具有重要意义。 展开更多
关键词 NiFe_(2)O_(4)八面体 气体传感 氢化 活性位点 传感反应机制
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1/4波长法和水平垂直谱比法场地放大反应差异性分析--以西克尔镇为例
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作者 李文倩 孙静 李姗姗 《内陆地震》 2023年第3期232-238,共7页
利用土层剪切波速数据及强震动记录,分别采用1/4波长法及水平垂直谱比法,得到了西克尔镇场地放大反应曲线。对比发现1/4波长法可以较好的估计场地放大反应,但不能准确估计场地卓越频率;水平垂直谱比法可以较好估计场地卓越频率,但得到... 利用土层剪切波速数据及强震动记录,分别采用1/4波长法及水平垂直谱比法,得到了西克尔镇场地放大反应曲线。对比发现1/4波长法可以较好的估计场地放大反应,但不能准确估计场地卓越频率;水平垂直谱比法可以较好估计场地卓越频率,但得到的场地放大反应偏小。在研究区,水平垂直谱比法估计场地放大反应偏小约1~2.5倍,尤其是周期在0.08~0.2 s范围内,场地放大反应偏小2.5倍左右。 展开更多
关键词 场地放大反应 1/4波长法 水平垂直谱比法 竖向地震动放大
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二维Nb2SiTe4基化合物稳定性、电子结构和光学性质的第一性原理研究 被引量:3
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作者 罗雄 孟威威 +4 位作者 陈国旭佳 管晓溪 贾双凤 郑赫 王建波 《物理学报》 SCIE EI CAS CSCD 北大核心 2020年第19期257-265,共9页
基于第一性原理计算,确定了3种稳定未被报道的Nb2SiTe4基化合物(A2BX4:Nb2SiSe4,Nb2SnTe4和Ta2GeTe4),研究了其电子结构,光学性质以及应力工程对其电子结构的调控.计算结果表明上述3种化合物具有类似Nb2SiTe4的窄带隙值、强的光吸收性... 基于第一性原理计算,确定了3种稳定未被报道的Nb2SiTe4基化合物(A2BX4:Nb2SiSe4,Nb2SnTe4和Ta2GeTe4),研究了其电子结构,光学性质以及应力工程对其电子结构的调控.计算结果表明上述3种化合物具有类似Nb2SiTe4的窄带隙值、强的光吸收性能以及显著的光学各向异性,可用于光电器件之中.其晶格常数范围为6.04Å≤a≤6.81Å,7.74Å≤b≤8.15Å.Ta2GeTe4的晶格参数与Nb2SiTe4几乎相同,带隙值减小了0.15 eV,可应用于远红外光探测.应力工程表明外加双轴拉伸应力可减小A2BX4体系带隙值.外加双轴压缩应力时,A2BX4体系价带顶轨道可出现反转(Nb2SiTe4,Nb2GeTe4和Ta2GeTe4),由B位阳离子占据态d轨道主导转变为B位阳离子占据态d轨道与X位阴离子满p轨道共同主导,导致带隙值变化趋势异常.我们预测该价带顶轨道的反转可有效降低空穴有效质量,促进载流子的迁移,有助于器件性能的提升. 展开更多
关键词 Nb2site4 元素替换 应力工程 第一性原理
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胃癌根治术后手术部位感染影响因素及血清MCP1、CA72-4、sCD14水平变化意义分析 被引量:4
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作者 张城榕 王峰 +3 位作者 庞思思 李鹏 艾热夏提·吐洪江 曲玉江 《现代肿瘤医学》 CAS 北大核心 2023年第12期2264-2270,共7页
目的:探究胃癌根治术后手术部位感染(surgical site infection,SSI)影响因素及血清单核细胞趋化蛋白-1(monocyte chemoattractant protein-1,MCP1)、糖类抗原72-4(carbohydrate antigen 72-4,CA72-4)、可溶性白细胞分化抗原-14(soluble ... 目的:探究胃癌根治术后手术部位感染(surgical site infection,SSI)影响因素及血清单核细胞趋化蛋白-1(monocyte chemoattractant protein-1,MCP1)、糖类抗原72-4(carbohydrate antigen 72-4,CA72-4)、可溶性白细胞分化抗原-14(soluble cluster of differentiation antigen-14,sCD14)水平变化意义。方法:选取2017年02月至2021年01月我院150例行胃癌根治术患者作为研究对象,根据患者术后是否出现SSI分为两组,感染组(n=35)与非感染组(n=115)。比较两组患者临床资料、手术前后血清MCP1、CA72-4、sCD14水平,分析胃癌根治术后SSI影响因素。绘制受试者工作特征曲线(receiver operating characteristic curve,ROC),评价胃癌根治术后血清MCP1、CA72-4、sCD14水平对SSI的诊断价值。分析术后血清MCP1、CA72-4、sCD14水平与感染程度(IPS评分)的相关性。比较术后血清MCP1、CA72-4、sCD14高水平与低水平患者病死率。结果:两组患者年龄、手术方式、临床分期、手术时间、糖尿病情况比较,差异有统计学意义(P<0.05)。感染组术后血清MCP1、CA72-4、sCD14水平高于非感染组(P<0.05)。Logistic回归方程结果显示,年龄、临床分期、糖尿病、手术方式、手术时间及术后血清MCP1、CA72-4、sCD14水平均为胃癌根治术后SSI的独立危险因素(P<0.05)。绘制胃癌根治术后血清MCP1、CA72-4、sCD14水平对SSI诊断价值的ROC曲线,结果显示胃癌根治术后血清MCP1、CA72-4、sCD14水平诊断SSI的曲线下面积(area under the curve,AUC)分别为0.804、0.768、0.777。应用Logistic二元回归拟合,构建各指标联合诊断的AUC,结果显示,联合检测的AUC为0.912。胃癌根治术后SSI患者IPS评分为(13.89±6.52)分。Pearson相关性分析可知,胃癌根治术后SSI患者血清MCP1、CA72-4、sCD14水平与感染程度呈正相关关系(P<0.05)。根据术后血清MCP1、CA72-4、sCD14水平分为高水平组与低水平组,术后血清MCP1、CA72-4、sCD14高水平组病死率明显高于低水平组,差异有统计学意义(P<0.05)。结论:胃癌根治术后SSI发病影响因素包括年龄、临床分期、糖尿病、手术方式、手术时间及术后血清MCP1、CA72-4、sCD14水平,且临床检测术后血清MCP1、CA72-4、sCD14水平,在SSI诊断、病情评估及预后预测中具有重要价值。 展开更多
关键词 原发性胃癌 胃癌根治术 手术部位感染 影响因素 MCP1 CA72-4 SCD14
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Numerical Simulation for Remediation Planning for 1,4-Dioxane-Contaminated Groundwater at Kuwana Illegal Dumping Site in Japan Based on the Concept of Verified Follow Up 被引量:1
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作者 Ramrav Hem Toru Furuichi +1 位作者 Kazuei Ishii Yu-Chi Weng 《Journal of Water Resource and Protection》 2013年第7期699-708,共10页
At Kuwana illegal dumping site in Japan, where hazardous waste was illegally dumped, groundwater was severely contaminated by Volatile Organic Compounds (VOCs). Groundwater was already remedied by conducting Pump-and-... At Kuwana illegal dumping site in Japan, where hazardous waste was illegally dumped, groundwater was severely contaminated by Volatile Organic Compounds (VOCs). Groundwater was already remedied by conducting Pump-and-Treat (P&T) after containment of all the waste by vertical slurry walls from 2002 to 2007. However, 1,4-dioxane was detected in both waste and groundwater outside of slurry walls after it was newly added into Japan environmental standards in late 2009, which suggested that the walls did not contain 1,4-dioxane completely. Our previous study developed a model to predict the 1,4-dioxane distribution in groundwater after the previous remediation at the site. In this study, numerical simulation was applied for remediation planning at the site based on the concept of Verified Follow Up (VF-UP) that had been proposed as a new approach to complete remediation effectively with consideration of future risks. The amount of waste to be removed and pumping plans were discussed by numerical simulation to achieve the remedial objective in which 1,4-dioxane in groundwater outside of walls is remedied within 10 years and 1,4-dioxane spreading throughout the walls is prevented in the case where a portion of waste is remained. Firstly, the amount of waste to be removed considering pumping plans for P&T was determined by scenario analysis. As a result, at least two-third of waste should be removed by combining with P&T. However, if the waste is remained, future risks of 1,4-dioxane spreading through the slurry walls may occur. Our simulation suggested that groundwater within the remaining waste must be pumped up at least 20 m3/d for containment of 1,4-dioxane within the remaining waste. In conclusion, our numerical simulation determined the amount of waste to be removed and the pumping plans for P&T to achieve the remedial objective effectively considering future risks based on the concept of VF-UP. 展开更多
关键词 REMEDIATION PLANNING Numerical Simulation Verified FOLLOW Up Pump-and-Treat 1 4-Dioxane-Contaminated Groundwater ILLEGAL DUMPING site
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B位Mn/W共掺杂对Bi_(4)Ti_(3)O_(12)铋层状压电陶瓷的电学性能影响 被引量:1
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作者 梁志豪 黄荣厦 张艺 《陶瓷学报》 CAS 北大核心 2023年第4期719-726,共8页
采用直接反应烧结法制备Mn/W共掺杂的Bi_(4)Ti_(3-x)(Mn_(1/3)W_(2/3))_(x)O_(12)(BITMW-100x,0.01<x<0.07)铋层状高温压电陶瓷,研究Mn/W掺杂含量对BITMW-100x陶瓷的结构和电学性能的影响。XRD图谱结果显示,所有样品均表现出单一... 采用直接反应烧结法制备Mn/W共掺杂的Bi_(4)Ti_(3-x)(Mn_(1/3)W_(2/3))_(x)O_(12)(BITMW-100x,0.01<x<0.07)铋层状高温压电陶瓷,研究Mn/W掺杂含量对BITMW-100x陶瓷的结构和电学性能的影响。XRD图谱结果显示,所有样品均表现出单一相。随着Mn/W掺杂含量的增加,SEM图谱中观察到陶瓷晶粒的尺寸呈现先变大后变小的趋势。介温图谱中发现Mn/W的掺杂能有效抑制Bi_(4)Ti_(3)O_(12)陶瓷样品的介电损耗,同时居里温度也呈现小幅度下降。Mn/W在取代Ti离子后能减少Bi_(4)Ti_(3)O_(12)陶瓷的氧空位缺陷浓度,减少氧空位对电畴的钉扎效应,提升压电系数。当Mn/W掺杂含量x=0.05时,陶瓷样品具有最佳的综合性能:介电损耗(tanδ)为0.7%,居里温度为674℃,压电常数(d_(33))为18.1pC·N^(-1),同时压电常数具有良好的热稳定性。 展开更多
关键词 压电陶瓷 Bi_(4)Ti_(3)O_(12) B位掺杂 铁电 铋层状结构
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4型禽腺病毒分离株SDLC202011的致病性及全基因组序列分析
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作者 王凯莉 刘成 +5 位作者 杜旭升 陈乐乐 曹胜亮 李玉保 路建彪 司振书 《畜牧与兽医》 CAS 北大核心 2023年第5期95-102,共8页
为了掌握4型禽腺病毒(FAdV-4)山东聊城分离株SDLC202011的致病特点及遗传变异情况,对其进行了致病性试验和全基因测序分析。结果表明:该分离株对21日龄SPF鸡的致死率为100%,感染鸡的心脏、肝脏、肾脏等器官均具有典型的病理变化,免疫组... 为了掌握4型禽腺病毒(FAdV-4)山东聊城分离株SDLC202011的致病特点及遗传变异情况,对其进行了致病性试验和全基因测序分析。结果表明:该分离株对21日龄SPF鸡的致死率为100%,感染鸡的心脏、肝脏、肾脏等器官均具有典型的病理变化,免疫组化显示肝脏、胰腺和肾脏中均检测到该病毒的抗原;全基因组序列长度为43826 bp,编码34个开放阅读框。与国外参考毒株相比,该毒株和国内其他毒株在35473~37439 bp均有1966 bp的缺失,该区域包含ORF19、ORF48和ORF27;与非致病性毒株相比,高致病力毒株在hexon、fiber1和fiber2分别有1、3和12个氨基酸位点突变,突变主要集中在fiber2。本研究结果表明分离株SDLC202011为高致病力毒株,可在肝脏、胰腺和肾脏等脏器中增殖,为进一步研究FAdV-4的致病机制及疫苗研发奠定了基础。 展开更多
关键词 FAdV-4 致病性 全基因组 开放阅读框 氨基酸位点
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SYNTHESIS AND STRUCTURE OF A LINEAR TRIVANADIUM COMPOUND(Ph_4P)[V_3(OC_6H_4S-o)_6]-SIMULATION OF THE VANADIUM SITE OF ALTERNATIVE NITROGENASE
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作者 Bei Sheng KANG Ling Hong WENG Liang Ren HUANG Xue Tai CHEN Han Qin LIU Jia Xi LU Fuzhou Laboratory of Structural Chemistry andFujian Institute of Research on the Structure of Matter Chinese Academy of Sciences,Fuzhou 350002 《Chinese Chemical Letters》 SCIE CAS CSCD 1990年第1期79-80,共2页
Compound(Ph_4P)[V_3MP_6](MPH_2=o-HOC_6H_4SH)was obtained by reaction of VCl_3 and Na_2MP in ethanol in the presence of Ph_4PBr.It is triclinic and crystallizes in space group P1,fw=1237.3,a=14.127(4), b=14.342(4),c=15... Compound(Ph_4P)[V_3MP_6](MPH_2=o-HOC_6H_4SH)was obtained by reaction of VCl_3 and Na_2MP in ethanol in the presence of Ph_4PBr.It is triclinic and crystallizes in space group P1,fw=1237.3,a=14.127(4), b=14.342(4),c=15.878(4);α=65.08(2),β=73.09(2),T=78.68(2)°;V=2781.3~3, Z=2,d_c=1.48 g/cm^3.Final R factor is 0.063.The three vanadium atoms are linearly arranged and bridged by the oxygen atoms and terminally chelated by the thiolato-atoms of the six MP^2-ligands in pseudo-S_6 symmetry. 展开更多
关键词 Ph4P SIMULATION OF THE VANADIUM site OF ALTERNATIVE NITROGENASE SYNTHESIS AND STRUCTURE OF A LINEAR TRIVANADIUM COMPOUND V3 site Figure Wang
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Optimizing geometric configuration of single Zn-N_(4) sites for boosting reciprocal transformation between aromatic alcohols and aldehydes
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作者 Shengjie Wei Yucheng Jin +7 位作者 Chunlin Lv Chao Lian Zheng Chen Xiao Liang Qinghua Zhang Xin Chen Dongdong Qi Zhi Li 《Nano Research》 SCIE EI CSCD 2023年第7期9132-9141,共10页
It is significant to optimize geometric configuration of metal catalytic sites and boost their catalytic activity.Herein,we synthesized isolated single Zn-N_(4)sites on N-doped carbon(Zn-CN)by pyrolyzing zeolite imida... It is significant to optimize geometric configuration of metal catalytic sites and boost their catalytic activity.Herein,we synthesized isolated single Zn-N_(4)sites on N-doped carbon(Zn-CN)by pyrolyzing zeolite imidazole framework-8(ZIF-8)at different temperatures.For the reciprocal transformation between benzyl alcohol and benzaldehyde,the catalytic activities of Zn-CN catalysts exhibited a volcano-like trend as the pyrolysis temperatures increased.The optimal catalyst was Zn-CN-900,with outstanding catalytic activity exceeding commercial 20 wt.%Pd/C and 20 wt.%Pt/C,promising to substitute the noble metalbased catalysts.X-ray absorption near-edge structure(XANES)measurements and density functional theory(DFT)calculation revealed the gradual transformation from tetrahedral ZnN_(4)sites of ZIF-8 into planar ZnN_(4)sites above 700℃,with the maximum planar ZnN_(4)sites in Zn-CN-900.The stronger adsorption between reactants and planar ZnN_(4)sites facilitated the activation of reactants compared with tetrahedral ZnN_(4)sites.This work will provide valuable insight into rational design of efficient catalysts by optimizing geometric configuration of catalytic sites. 展开更多
关键词 geometric configuration single zn-n_(4)sites benzyl alcohol oxidation hydrogen transfer reaction
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Expression of hepatocyte nuclear factor 4 alpha,wingless-related integration site,andβ-catenin in clinical gastric cancer
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作者 Qian Hu Ling-Li Li +1 位作者 Ze Peng Ping Yi 《World Journal of Clinical Cases》 SCIE 2022年第21期7242-7255,共14页
BACKGROUND Gastric cancer(GC)is the second most common cause of cancer-related deaths worldwide.Hepatocyte nuclear factor 4 alpha(HNF4α)that belongs to the nuclear hormone receptor superfamily,is overexpressed in GC ... BACKGROUND Gastric cancer(GC)is the second most common cause of cancer-related deaths worldwide.Hepatocyte nuclear factor 4 alpha(HNF4α)that belongs to the nuclear hormone receptor superfamily,is overexpressed in GC tissues,and might be involved in the development of GC by regulating its downstream winglessrelated integration site(WNT)/β-catenin signaling.AIM To clarify the expression of HNF4α/WNT5a/β-catenin signaling proteins in clinical GC tissues.METHODS We immunohistochemically stained pathological blocks of GC and matched paracancerous tissues.The intensity of HNF4α,WNT5a andβ-catenin staining in the tumor cells was determined according to cell rates and staining intensity.The correlations between GC and HNF4α,WNT5a,andβ-catenin expression using chisquare and paired chi-square tests.Relationships between double-positive HNF4αand WNT5a expression and types of gastric tumor tissues were assessed using regression analysis.Correlations between HNF4αand WNT5a expression at the RNA level in GC tissues found in the TCGA database were analyzed using Pearson correlation coefficients.RESULTS We found more abundant HNF4αand WNT5a proteins in GC,especially in mucinous adenocarcinoma and mixed GC than in adjacent tissues(P<0.001).Low and high levels of cytoplasmicβ-catenin respectively expressed in GC and adjacent tissues(P<0.001)were not significantly associated with pathological parameters.CONCLUSION The expressions of HNF4αand WNT5a could serve as early diagnostic biomarkers for GC. 展开更多
关键词 Β-CATENIN BIOMARKER Gastric cancer Hepatocyte nuclear factor 4 alpha Wingless-related integration site
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WNT4基因在妊娠妇女中的表达变化及对早产的预测价值研究
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作者 蔡大芬 熊琼英 邱兰 《标记免疫分析与临床》 CAS 2023年第12期2061-2064,2122,共5页
目的探讨无翅型小鼠乳房肿瘤病毒整合位点家族成员4(WNT4)基因在妊娠妇女中的表达变化及对早产的预测价值。方法采用便利抽样法,选取2019年1月至12月在本院分娩的80例妊娠孕妇为研究对象,根据分娩结局分为自发性早产组、足月组。比较两... 目的探讨无翅型小鼠乳房肿瘤病毒整合位点家族成员4(WNT4)基因在妊娠妇女中的表达变化及对早产的预测价值。方法采用便利抽样法,选取2019年1月至12月在本院分娩的80例妊娠孕妇为研究对象,根据分娩结局分为自发性早产组、足月组。比较两组孕妇一般资料及静脉血、脐带血WNT4表达水平变化,采用多因素Logistic回归分析进行自发性早产影响因素分析;绘制受试者工作特征曲线(ROC)评估WNT4表达水平对自发性早产的预测价值。结果自发性早产组与足月组分娩孕周、新生儿出生体重、C反应蛋白、宫颈内口应变平均值、宫颈长度、静脉血及脐带血WNT4表达水平比较,差异有统计学意义(P<0.05);多因素Logistic回归分析显示,宫颈长度、静脉血及脐带血WNT4表达水平为自发性早产危险因素(P<0.05);ROC曲线显示,静脉血及脐带血WNT4表达检测对自发性早产预测的灵敏度、特异性较高,且联合检查时灵敏度、特异性更高。结论相较于足月产孕妇WNT4基因在自发性早产孕妇中表达升高;临床检测孕妇静脉血及脐带血WNT4表达对预测早产有一定价值。 展开更多
关键词 妊娠妇女 早产 无翅型小鼠乳房肿瘤病毒整合位点家族成员4
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陕西境内遗址表面CaSO_(4)·2H_(2)O产生之水盐运移规律研究
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作者 王永进 纪娟 +4 位作者 石美荣 甄刚 张刚 相建凯 董少华 《文物保护与考古科学》 北大核心 2023年第2期90-96,共7页
陕西境内遗址出土后短时间内表面产生白色物质CaSO_(4)·2H_(2)O是非常普遍的现象。本研究利用土柱模拟遗址出土后表面产生CaSO_(4)·2H_(2)O的过程,通过监测土柱中土壤的湿度、含盐量及离子变化综合分析CaSO_(4)·2H_(2)O... 陕西境内遗址出土后短时间内表面产生白色物质CaSO_(4)·2H_(2)O是非常普遍的现象。本研究利用土柱模拟遗址出土后表面产生CaSO_(4)·2H_(2)O的过程,通过监测土柱中土壤的湿度、含盐量及离子变化综合分析CaSO_(4)·2H_(2)O产生的原因,研究结果表明遗址出土后形成了新的界面层,在蒸发的作用下,地下水沿土壤孔隙向上迁移,同时将可溶盐带入土壤中,表面的可溶盐含量逐渐增大,达到峰值后不再增加,实验后测得表面土壤中的Ca^(2+)和SO_(4)^(2-)是原始土壤的数十倍,说明遗址表面产生CaSO_(4)·2H_(2)O是水盐运移的结果。本研究可为遗址出土后预防CaSO_(4)·2H_(2)O的产生提供依据。 展开更多
关键词 土遗址 出土 表面白色物质 CaSO_(4)·2H_(2)O
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揭示层状晶态CoMoO_(4)的水裂解电催化机制:从晶面选择到活性位点设计的理论研究
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作者 耿仕鹏 陈利明 +4 位作者 陈海鑫 王毅 丁朝斌 蔡丹丹 宋树芹 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2023年第7期334-342,共9页
电解水制氢具有效率高、操作简单、易于耦合可再生能源等优点,被认为是大规模产氢最有希望的技术之一.通常贵金属基材料Pt和Ir(Ru)O_(2)分别用作阴极析氢反应(HER)和阳极析氧反应(OER)催化剂,进而提高水裂解效率.然而,它们的稀缺性、成... 电解水制氢具有效率高、操作简单、易于耦合可再生能源等优点,被认为是大规模产氢最有希望的技术之一.通常贵金属基材料Pt和Ir(Ru)O_(2)分别用作阴极析氢反应(HER)和阳极析氧反应(OER)催化剂,进而提高水裂解效率.然而,它们的稀缺性、成本高和稳定性差等缺点严重限制了在电解水中的大规模应用.因此,急需开发廉价且高效的水裂解电催化剂.钼酸钴(CoMoO_(4))由于成本低、储量丰富、氧化还原活性位点多和稳定性高等优点,被认为是替代贵金属基催化剂的理想候选者.但由于CoMoO_(4)复杂的单斜晶体结构,从原子层面揭示其HER和OER电催化机理仍然是一个极大挑战,而在原子水平探索电催化剂不同晶面的催化活性对理解电催化机制和识别活性位点起着推动作用.本文采用密度泛函理论(DFT)从层状晶态CoMoO_(4)的晶面选择到活性位点设计系统研究了其水裂解电催化机制.CoMoO_(4)沿[110]晶格方向呈现层状排列晶体特征,通过表面能计算并基于Wulff原则构造了CoMoO_(4)的热力学稳定晶体结构,结果表明,具有较低表面能的(110)A(62 mJm^(-2))和(001)A(179mJm^(-2)面均为理论热力学稳定晶体结构的主导晶面,分别占据了64.25%和23.53%.因此以(110)A和(001)A晶面为研究对象,重点研究了其碱性水裂解的电催化活性及其深入的催化机制.结果发现,在CoMoO_(4)的(110)A面上的O_(3)位点吸附的H可以与两个氧原子(O_(3)和Oadj)相互作用,理论计算得到的氢吸附吉布斯自由能(ΔGH*)仅为0.22 eV,对应了最高的类似Pt的交换电流密度i0,所以其表现出最优异的HER活性;另外,(110)A面水解离(Volmer反应)能垒约为1.6 eV,远低于(001)A的4.6 eV,说明(110)A面拥有比(001)A面更好的H_(2)O解离能力,更有利于碱性溶液中的HER.过渡态计算结果表明,(110)A上的H*更倾向于与另一个来自吸附水的H结合,Heyrovsky步骤的能垒为1.63 eV,低于两个H*结合形成H_(2)的Tafel步骤能垒(2.04 eV).因此,CoMoO_(4)催化剂上的HER是沿着Volmer-Heyrovsky步骤进行的.此外,根据吉布斯自由能计算,(110)A面上OER过电位仅为0.74 V,优于(001)A面(0.84 V),这是因为(110)A面的Co和O间的结合力更强,中间体*O的吸附状态更稳定,使得决速步(*OH→*O)能垒降低.综上,本文对CoMoO_(4)及其同构物质如Mn(Ni,Fe)MoO4纳米催化剂的选择性合成和电催化机理研究具有借鉴意义. 展开更多
关键词 密度泛函理论 水裂解 层状晶体CoMoO_(4) 晶面选择 活性位点设计
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浅谈催化还原4-硝基酚反应中转换频率的计算
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作者 邢立文 《广州化工》 CAS 2023年第7期193-195,共3页
4-硝基酚在还原剂和催化剂共存的条件下可以生成4-氨基酚。计算该催化反应的转换频率(TOF)能够反映所用催化剂材料的本征活性。很多学生盲目地根据文献报道的公式计算TOF数值时容易出现错误,这可能是由于没有真正理解TOF的定义及其计算... 4-硝基酚在还原剂和催化剂共存的条件下可以生成4-氨基酚。计算该催化反应的转换频率(TOF)能够反映所用催化剂材料的本征活性。很多学生盲目地根据文献报道的公式计算TOF数值时容易出现错误,这可能是由于没有真正理解TOF的定义及其计算公式的由来。本文针对这类一级或准一级反应的TOF计算公式进行了详细的数学推导,以期在实验教学和科研实践中为学生们更加深入地理解和掌握TOF计算提供有益参考。 展开更多
关键词 转换频率 计算公式 催化反应 活性位 4-硝基酚
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硫酸负载对Pt/SO_(4)^(2-)-(ZrO_(2)-Al_(2)O_(3))催化剂性能的影响
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作者 宋宇 辛靖 +4 位作者 张海洪 曾土城 范文轩 王廷海 王鹏照 《石化技术与应用》 CAS 2023年第4期251-255,共5页
采用共沉淀-浸渍法制备了系列硫酸负载催化剂Pt/SO_(4)^(2-)-(ZrO_(2)-Al_(2)O_(3)),利用X射线衍射仪、物理吸附仪、红外光谱仪等对其进行了表征,并在固定床微型反应装置上对其催化异丁烷正构化反应性能进行了评价。结果表明:硫酸单层... 采用共沉淀-浸渍法制备了系列硫酸负载催化剂Pt/SO_(4)^(2-)-(ZrO_(2)-Al_(2)O_(3)),利用X射线衍射仪、物理吸附仪、红外光谱仪等对其进行了表征,并在固定床微型反应装置上对其催化异丁烷正构化反应性能进行了评价。结果表明:硫酸单层分散于载体表面,硫酸负载不利于四方晶相ZrO_(2)长大;随着硫酸负载量的增加,催化剂介孔结构的有序性增强且孔径减小,孔径最小降为3.41 nm,孔容可提高至0.091 cm^(3)/g,比表面积增至100 m^(2)/g以上;在反应温度为250℃的条件下,硫酸负载量为15%时,异丁烷转化率高达41.74%;硫酸负载量为2%时,正丁烷选择性最高为93.91%。 展开更多
关键词 异丁烷 正构化 催化剂 硫酸 Pt/SO_(4)^(2-)-(ZrO_(2)-Al_(2)O_(3)) 单层分散 酸性位
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