检索结果-南通市图书馆

Modulating proton binding energy on the tungsten carbide nanowires surfaces for boosting hydrogen evolution in acid

Journal of Energy Chemistry 2021年第11期30卷 610-616,I0014页

作者： Qjngshui Hong Tangyi Li Shisheng Zheng Haibiao Chen wenju Ren Honghao Chu Kuangda Xu Zongwei Mei Feng Pan School of Advanced Materials Peking UniversityShenzhen Graduate SchoolShenzhen 518055GuangdongChina School of Advance Manufacturing Engineering Chongqing University of Posts and TelecommunicationsChongqing 400065China

ungsten carbides have attracted wide attentions as Pt substitute electrocatalysts for hydrogen evolution reaction (HER), due to their good stability in an acid environment and Pt-like behaviour in hydrolysis. However, quantum chemistry calculations predict that the strong tungsten-hydrogen bonding hinders hydrogen desorption and restricts the overall catalytic activity. Synergistic modulation of host and guest electronic interaction can change the local work function of a compound, and therefore, improve its electrocatalytic activity over either of the elements individually. Herein, we develop a creative and facile solid-state approach to synthesize self-supported carbon-encapsulated single-phase WC hybrid nanowires arrays (nanoarrays) as HER catalyst. The theoretical calculations reveal that carbon encapsulation modifies the Gibbs free energy of H* values for the WC adsorption sites, endowing a more favorable C@WC active site for HER. The experimental results exhibit that the hybrid WC nanoarrays possess remarkable Pt-like catalytic behavior, with superior activity and stability in an acidic media, which can be compared to the best non-noble metal catalysts reported to date for hydrogen evolution reaction. The present results and the facile synthesis method open up an exciting avenue for developing cost-effective catalysts with controllable morphology and functionality for scalable hydrogen generation and other carbide nanomaterials applicable to a range of electrocatalytic reactions.

关键词： Carbon-encapsulated tungsten carbide Solid-state synthesis Self-supported nanoarrays electrode Hydrogen evolution reaction First-principles calculations

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

基于农用地分等成果的耕地占补平衡按等折算

引用

农业工程学报 2009年第1期25卷 244-248页

作者：于雷周勇郧文聚夏天华中师范大学城市与环境科学学院武汉430079 国土资源部土地整理中心北京100035

中国近十年来,随着社会经济的全面发展,城市化进程加快,耕地保护的形势不容乐观,在耕地占补工作中存在"占多补少、占优补劣"的现象。为确保补充耕地面积,提高补充耕地质量,解决国家粮食安全问题,进行农用地分等成果在补充耕地数量质量... 详细信息

中国近十年来,随着社会经济的全面发展,城市化进程加快,耕地保护的形势不容乐观,在耕地占补工作中存在"占多补少、占优补劣"的现象。为确保补充耕地面积,提高补充耕地质量,解决国家粮食安全问题,进行农用地分等成果在补充耕地数量质量按等级折算中的应用研究。本文选择湖北省为研究区域,以湖北省农用地自然质量等成果作为研究数据源,采用分层抽样的方法从数据源中选取适量的具有代表性的样本,以这些样本的农用地自然质量等指数和面积数据等相关信息建立基础数据库。在此基础上,开展补充耕地数量质量按等级折算技术方法研究:首先,采用面积加权平均模型计算得到各自然质量等别的平均自然质量等指数;然后,构建按等折算系数计算模型;最终建立各等别间折算关系表。通过本研究得到省级耕地占补平衡等级折算系数表,为严格土地管理和耕地占补平衡的贯彻落实提供理论依据。

关键词：农用地利用区域规划自然质量等级耕地占补平衡等级折算

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Temporal changes in seasonal precipitation over the Sahara Desert from 1979 to 2016

引用

Research in Cold and Arid Regions 2021年第3期13卷 220-233页

作者： Sindikubwabo Celestin Feng Qi RuoLin Li wenju Cheng Jian Ma Habiyakare Telesphore Nzabarinda Vincent Key Laboratory of Eco-hydrology of Inland River Basin Northwest Institute of Eco-Environment and ResourcesChinese Academy of Sciences(CAS)LanzhouGansu 730000China University of Chinese Academy of Sciences Beijing 100049China Qilian Mountains Eco environment Research Center LanzhouGansu 730000China Academy of Water Resources Conservation Forests in Qilian Mountains ZhangyeGansu 734000China

Rainfall variability dominates livelihoods in all countries of Saharan *** better understand the processes involved in Sahara precipitation changes,we used the Global Precipitation Climatology Center(GPCC)dataset to examine dry and wet seasonal trends in the Sahara region from 1979 to *** also used the European Centre for Medium-Range Weather Forecasts(ECMWF)to evaluate the general atmospheric circulation associated with seasonal change of Sahara *** Mann-Kendall test and Theil sens'slope estimator methods were adopted to test and estimate the significance and weight of precipitation trend,*** results revealed that Sahara precipitation has increased *** seasonal evaluation shows a positive trend of 0.42 mm/decade and 1.43 mm/decade in JAS(June,August,and September)seasons for the northern and southern Saharan Desert,***,the JFMA(January,February,March,and April)period shows a negative trend but not statistically *** examination of the general circulation and moisture transport changes suggested an increase of rainfall in southern *** wet period is also driven by northward penetration of moisture originating from the Sahel region,African Easterly Jet(AEJ),and weakening in the upper tropospheric zonal *** rainfall has also been likely associated with positive anomalies of sea surface temperature(SST)in the North Tropical Atlantic(NTA)and the Mediterranean Sea.

关键词： Sahara precipitation variability arid Africa climate

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Selective annulation of benzamides with internal alkynes catalyzed by an electron-deficient rhodium catalyst

引用

Chinese Chemical Letters 2021年第5期32卷 1717-1720页

作者： Ping Zhang wenju Chang Hongyun Jiao Yanshang Kang Wenxuan Zhao Peipei Cui Yong Liang Wei-Yin Sun Yi Lu Coordination Chemistry Institute State Key Laboratory of Coordination ChemistrySchool of Chemistry and Chemical EngineeringNanjing National Laboratory of MicrostructuresCollaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210023China State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic MaterialsSchool of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023China

An electron-deficient[CpERhCl2]2 catalyzed annulation of N-pentafluorophenylbenzamides with internal alkynes was successfully established under mild reaction conditions,with the assistance of Lewis acid silver ***,electron-deficient benzamide substrates were smoothly transformed into the desired products in this catalytic *** catalytic system showed a broad tolerance for different substituents on the aromatic rings or aryl,alkyl-substituted alkynes.

关键词： Electron-deficient rhodium C—H activation Annulation Benzamide Alkyne

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A signal subspace dimension estimator based on F-norm with application to subspace-based multi-channel speech enhancement

引用

Chinese Journal of Acoustics 2012年第3期31卷 353-368页

作者： LI Chao LIU wenju National Laboratory of Pattern Recognition Institute of Automation Chinese Academy of Sciences Beijing 100190

Although the signal subspace approach has been studied extensively for speech enhancement, no good solution has been found to identify signal subspace dimension in multi- channel situation. This paper presents a signal subspace dimension estimator based on F-norm of correlation matrix, with which subspace-based multi-channel speech enhancement is robust to adverse acoustic environments such as room reverberation and low input signal to noise ratio （SNR）. Experiments demonstrate the presented method leads to more noise reduction and less speech distortion comparing with traditional methods.

关键词：信号子空间语音增强维数估计 F-范数多通道基础应用系数矩阵

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Porous metal oxides in the role of electrochemical CO_(2) reduction reaction

引用

Journal of Energy Chemistry 2024年第1期88卷 373-398,I0009页

作者： Ziqi Zhang Jinyun Xu Yu Zhang Liping Zhao Ming Li Guoqiang Zhong Di Zhao Minjing Li Xudong Hu wenju Zhu Chunming Zheng Xiaohong Sun School of Chemical Engineering and Technology Tianjin Key Laboratory of Green Chemical Technology and Process EngineeringState Key Laboratory of Separation Membrane and Membrane ProcessesTiangong UniversityTianjin 300387China School of Materials Science and Engineering Key Laboratory of Advanced Ceramics and Machining TechnologyMinistry of EducationTianjin UniversityTianjin 300072China

The global energy-related CO_(2) emissions have rapidly increased as the world economy heavily relied on fossil *** paper explores the pressing challenge of CO_(2) emissions and highlights the role of porous metal oxide materials in the electrocatalytic reduction of CO_(2)(CO_(2)RR).The focus is on the development of robust and selective catalysts,particularly metal and metal-oxide-based *** metal oxides offer high surface area,enhancing the accessibility to active sites and improving reaction *** tunability of these materials allows for tailored catalytic behavior,targeting optimized reaction mechanisms for CO_(2)*** work also discusses the various synthesis strategies and identifies key structural and compositional features,addressing challenges like high overpotential,poor selectivity,and low *** on these insights,we suggest avenues for future research on porous metal oxide materials for electrochemical CO_(2) reduction.

关键词： CO_(2)reduction Carbon dioxide Transformation Porous metal oxides Electrocatalysis

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Wavelength-Dependent Solar N_(2) Fixation into Ammonia and Nitrate in Pure Water

引用

Research 2020年第1期2020卷 581-592页

作者： wenju Ren Zongwei Mei Shisheng Zheng Shunning Li Yuanmin Zhu Jiaxin Zheng Yuan Lin Haibiao Chen Meng Gu Feng Pan School of Advanced Materials Peking UniversityShenzhen Graduate SchoolChina School of Advance Manufacturing Engineering Chongqing University of Posts and TelecommunicationsChongqingChina Department of Materials Science and Engineering Southern University of Science and TechnologyChina SUSTech Academy for Advanced Interdisciplinary Studies Southern University of Science and TechnologyChina Institute of Chemistry Chinese Academy of SciencesBeijingChina

Solar-driven N_(2) fixation using a photocatalyst in water presents a promising alternative to the traditional Haber-Bosch process in terms of both energy efficiency and environmental *** present,the product of solar N_(2) fixation is either NH_(4)^(+)or NO_(3)^(-).Few reports described the simultaneous formation of ammonia(NH_(4)^(+))and nitrate(NO_(3)^(-))by a photocatalytic reaction and the related *** this work,we report a strategy to photocatalytically fix nitrogen through simultaneous reduction and oxidation to produce NH_(4)^(+)and NO_(3)^(-)byW18O49 nanowires in pure *** underlying mechanism of wavelength-dependent N_(2) fixation in the presence of surface defects is proposed,with an emphasis on oxygen vacancies that not only facilitate the activation and dissociation of N_(2) but also improve light absorption and the separation of the photoexcited *** NH_(4)^(+)and NO_(3)^(-)can be produced in pure water under a simulated solar light and even till the wavelength reaching 730 *** maximum quantum efficiency reaches 9%at 365 *** calculation reveals that disproportionation reaction of the N_(2) molecule is more energetically favorable than either reduction or oxidation *** is worth noting that the molar fraction of NH_(4)^(+)in the total product(NH_(4)^(+)plus NO_(3)^(-))shows an inverted volcano shape from 365nm to 730 *** increased fraction of NO_(3)^(-)from 365 nm to around 427 nm results from the competition between the oxygen evolution reaction(OER)at W sites without oxygen vacancies and the N_(2) oxidation reaction(NOR)at oxygen vacancy sites,which is driven by the intrinsically delocalized photoexcited *** 427nm to 730 nm,NOR is energetically restricted due to its higher equilibrium potential than that of OER,accompanied by the localized photoexcited holes on oxygen *** disproportionation of N_(2) is achieved within a range of wavelength from~427nm to~515 *** work presents a rati

关键词： mechanism excited catalyst

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Accounting and Responsibility Allocation on Carbon Emissions Embodied in International Trade

引用

China Economist 2012年第2期7卷 50-59页

作者： Wang wenju Xiang Qifeng Economics School Capital University of Economics and BusinessBeijingChina Statistics and Mathematics School Yunnan University of Finance and EconomicsKunmingChina

This paper calculated the scale of carbon emissions embodied in the import and export of the world＇s major countries based on input-output principles and international trade data, as well as data on various countries＇carbon emissions in 2005 from domestic consumption and emissions embodied in trade. The results illustrate that, because of international trade, consumers in developed countries should bear the responsibility for a large portion of CO2 emissions. The researchers separated the net transfer balance of embodied emissions in international trade according to four different effects： size effect, exchange rate effect, structural effect, and pure technical effect, all of which favor the sharing of responsibilities between producers and consumers.

关键词： embodied carbon emissions international trade net transfer Logarithmic an Divisia Index (LMDI)JEL: Q48

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Long-term manure application increased soil organic carbon and nitrogen mineralization through accumulation of unprotected and physically protected carbon fractions

引用

Pedosphere 2023年第2期33卷 343-354页

作者： Muhammad Nadeem ASHRAF Cheng HU Xiangru XU Tariq AZIZ Lei WU Muhammad Ahmed WAQAS Muhammad FAROOQ Xu HU wenju ZHANG Minggang XU Key Laboratory of Cultivated Land Quality Monitoring and Evaluation Ministry of Agriculture and Rural AffairsInstitute of Agricultural Resources and Regional PlanningChinese Academy of Agricultural SciencesBeijing 100081(China) Institute of Soil and Environmental Sciences University of AgricultureFaisalabad 38040(Pakistan) Institute of Plant Protection and Soil Science Hubei Academy of Agricultural SciencesWuhan 430064(China) Institute of Soil and Environmental Sciences University of AgricultureFaisalabadSub-Campus DepalpurOkara 56130(Pakistan) Institute of Environment and Sustainable Development in Agriculture Chinese Academy of Agricultural SciencesBeijing 100081(China) Department of Plant Sciences College of Agricultural and Marine SciencesSultan Qaboos UniversityAl-Khoud 123(Oman) Shanxi Province Key Laboratory of Soil Environment and Nutrient Resources Engineer and Technology Academy of Ecology and EnvironmentShanxi Agricultural UniversityTaiyuan 030031(China)

Soil organic carbon(SOC)and nitrogen(N)mineralization are important biogeochemical processes associated with soil *** processes are influenced by physically,chemically,and biologically stabilized SOC fractions,the mechanisms of which are not well *** present study was conducted to evaluate the combined effect of manure and mineral fertilizers on the contents of SOC fractions to promote the mineralization of SOC and *** included:i)no fertilizer control(CK);ii)a combination of mineral N,phosphorus,and potassium fertilizers(NPK);iii)manure alone(M);iv)manure combined with NPK(MNPK);and v)a high dose of manure combined with NPK(hMNPK).The combined uses of manure and mineral fertilizers(MNPK and hMNPK)enhanced the accumulation of the unprotected coarse particulate organic carbon(C)fraction(cPOC)by 44%-72%compared to *** applications(M,MNPK and hMNPK)enhanced physically microaggregate-protected organic C(μagg),physicochemically protected organic C within the microaggregate-derived silt(μsilt)fraction(H-μsilt),and physicobiochemically protected organic C within theμsilt fraction(NH-μsilt)by 30%-56%,62%-150%,and 27%-51%,*** contrast,all chemically and biochemically protected SOC fractions showed a minor response to manure *** of cPOC,μagg,H-μsilt,and physicochemically protected organic C within the microaggregate-derived clay fraction(H-μclay)significantly contributed to the mineralization of SOC and N,resulting in a significant increase in rice grain yield with long-term manure *** summary,long-term combined use of manure and mineral fertilizers improved SOC accumulation in unprotected and physically protected fractions,which enhanced SOC and N mineralization and benefited soil productivity in a rice-wheat cropping system.

关键词： fertilization strategy grain yield organic C fraction organic matter stabilization protection mechanism

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Auditory filter based broadband MUSIC algorithm for sound source localization

引用

Chinese Journal of Acoustics 2013年第4期32卷 439-453页

作者： LIAO Fengchai LI Peng LIU wenju Department of Math and Computer Science Sanming University Sanming Digital Content Technique and Service Research Center Institute of Automation Chinese Academy of Sciences National Key Laboratory of Pattern Recognition Institute of Automation Chinese Academy of Sciences

Based on the analysis of the shortcomings of broadband MUSIC algorithm with short-time Fourier transform （SF-MUSIC） for sound source localization, a broadband MUSIC algorithm with auditory filter （AF-MUSIC） was proposed. The proposed algorithm first em- ploys auditory filter bank to decompose the signals received on the microphone array, and then locates the sound source with MUSIC algorithm over every frequency channel. At last, by combining with the subinterval frequency estimation, the final localization result is gained. Evaluations on the proposed algorithm prove that comparing with the SF-MUSIC algorithm, the AF-MUSIC algorithm decreases the average error of the estimation results with 2.5479 de- gree in different source conditions. The accuracy of sound source DOA estimation is enhanced effectively.

关键词： MUSIC SF DOA

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：