检索结果-南通市图书馆

Geology and Geochemistry of K-feldspar Veins in Lamprophyre at the Zhenyuan Gold Deposit,Yunnan,Southwest China:Implications for Gold Mineralization

引用

Acta Geologica Sinica(English Edition) 2024年第1期98卷 104-116页

作者： ZHANG Huichao CHAI Peng ZHANG Hongrui ZHOU Limin HOU Zengqian Key Laboratory of Submarine Geosciences Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China Key Laboratory of Marine Hazards Forecasting Ministry of Natural ResourcesHohai UniversityNanjing 210024China National Research Center for Geoanalysis Beijing 100037China

Lamprophyres typically appear in hydrothermal Gold deposits.The relationship between lamprophyres and Gold deposits is investigated widely.Some researchers suggest that the emplacement of lamprophyres triggers Gold mineralization,whereas others hypothesize that the formation of lamprophyres increases the fertility of mantle sources and ore-forming fluids.K-feldspar veins,with ages between those of lamprophyres and Gold deposits,appear in lamprophyres in Zhenyuan.Therefore,K-feldspar veins are ideal for investigating the relationship between lamprophyres and Gold deposits.Phlogopite in K-feldspar veins has lower Mg#,Ni,and Cr contents and higher TiO2,Li,Ba,Sr,Sc,Zr,Nb,and Cs contents than phlogopite in lamprophyres.The in-situ Sr isotopic values of apatites(0.7063–0.7066)in K-feldspar veins are within the range for apatites(0.7064–0.7078)from lamprophyres.High large-ion lithophile element concentrations and low Nb and Ta concentrations in phlogopite from lamprophyres,in addition to high(87Sr/86Sr)i values of apatite(0.7064–0.7078),indicate that the magma parental to these phlogopite and apatite crystals is derived from an enriched mantle.Kfeldspar veins are genetically correlated with lamprophyres,whereas sulfide mineral assemblage and trace element compositions of pyrite in K-feldspar veins suggest that K-feldspar veins in lamprophyres are not directly related to Gold mineralization of the Zhenyuan deposit.

关键词： lamprophyre K-feldspar vein apatite Sr isotope Gold Zhenyuan deposit Yunnan

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

On the time-varying correlations between oil-,Gold-,and stock markets:The heterogeneous roles of policy uncertainty in the US and China

引用

Petroleum Science 2022年第3期19卷 1420-1432页

作者： Wen Zhao Yu-Dong Wang School of Economics and Management Nanjing University of Science and TechnologyNanjing210094China

This paper investigates the effects of economic policy uncertainty(EPU)and monetary policy uncertainty(MPU)in the US and China on oil-stock and Gold-stock correlations.A quantile regression approach is employed to analyze the heterogeneous impacts under different market correlation regimes.Our findings suggest that the“US impact”prevails across all market correlations in the sample,while“China impact”is found for oil-stock correlations.Furthermore,the impacts of EPU and MPU on correlations of different asset pairs exhibit heterogeneity in direction and in different correlation regimes.EPU and MPU have homogenously negative effects on Gold-stock correlations across various correlation regimes.Differently,in terms of oil-stock correlations,they exhibit more significant and stronger positive impacts in the medium and high correlation regime than in the low correlation regime.Gold can provide a better diversification for stock market risks than crude oil during the period of high level of economic uncertainty.

关键词： Policy uncertainty Crude oil Gold Cross-asset correlations Quantile regression

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

Enantioselectivity Tunable Gold-Catalyzed Intermolecular[3+2]Cycloaddition of N-Allenamides with Nitrones

引用

Chinese Journal of Chemistry 2022年第12期40卷 1407-1412,I0002页

作者： Bing Xu Zhan-Ming Zhang Jie Han Guangxin Gu Junliang Zhang Department of Chemistry Fudan University2005 Songhu RoadShanghai 200438China Department of Materials Science Fudan University2005 Songhu RoadShanghai 200438China Zhuhai Fudan Innovation Institute ZhuhaiGuangdong 519000China

A highly enantioselective Gold-catalyzed intermolecular[3+2]cycloaddition of N-allenamides with nitrones was realized by the application of Ming-Phos M6 as a chiral ligand.Both enantiomers of the cycloadducts with opposite configuration could be obtained in high yields with high regio-and enantioselectivity by the employment of either diastereomer of the chiral ligand.The acidic N—H bond(hydrogen bonding)of sulfinamide moiety of Ming-Phos and pentaflurophenyl substituent(fluorine effect)may play important roles in enhancement of enantioselectivity,that is,Ming-Phos is a multifunctional ligand in this transformation.

关键词： Gold Asymmetric catalysis Fluorine effect Cycloaddition Multifunctional ligand

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

Extreme dependencies and spillovers between Gold and stock markets:evidence from MENA countries

引用

Financial Innovation 2023年第1期9卷 1449-1475页

作者： Walid Mensi Debasish Maitra Refk Selmi Xuan Vinh Vo Department of Economics and Finance College of Economics and Political ScienceSultan Qaboos UniversityMuscatOman Institute of Business Research University of Economics Ho Chi Minh CityHo Chi Minh CityVietnam Indian Institute of Management Indore IndoreIndia ESC Pau Business School PauFrance Institute of Business Research and CFVG University of Economics Ho Chi Minh CityHo Chi Minh CityVietnam

This study addresses whether Gold exhibits the function of a hedge or safe haven as often referred to in academia.It contributes to the existing literature by(i)revisiting this question for the principal stock markets in the Middle East and North Africa(MENA)region and(ii)using the copula-quantile-on-quantile and conditional value at risk methods to detail the risks facing market participants provided with accurate information about various Gold and stock market scenarios(i.e.,bear,normal,bull).The results provide strong evidence of quantile dependence between Gold and stock returns.Positive correlations are found between MENA Gold and stock markets when both are bullish.Conversely,when stock returns are bearish,Gold markets show negative correlations with MENA stock markets.The risk spillover from Gold to stock markets intensified during the global financial and European crises.Given the risk spillover between Gold and stock markets,investors in MENA markets should be careful when considering Gold as a safe haven because its effectiveness as a hedge is not the same in all MENA stock markets.Investors and portfolio managers should rebalance their portfolio compositions under various Gold and stock market conditions.Overall,such precise insights about the heterogeneous linkages and spillovers between Gold and MENA stock returns provide potential input for developing effective hedging strategies and optimal portfolio allocations.

关键词： Copula CoVaR Extreme dependence Gold MENA markets Risk spillovers

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

Diversification evidence of bitcoin and Gold from wavelet analysis

引用

Financial Innovation 2023年第1期9卷 2584-2619页

作者： Rubaiyat Ahsan Bhuiyan Afzol Husain Changyong Zhang Faculty of Business Curtin UniversityMiriMalaysia School of Business Swinburne University of TechnologyKuchingSarawakMalaysia

To measure the diversification capability of Bitcoin,this study employs wavelet analysis to investigate the coherence of Bitcoin price with the equity markets of both the emerging and developed economies,considering the COVID-19 pandemic and the recent Russia-Ukraine war.The results based on the data from January 9,2014 to May 31,2022 reveal that compared with Gold,Bitcoin consistently provides diversification opportunities with all six representative market indices examined,specifically under the normal market condition.In particular,for short-term horizons,Bitcoin shows favorably low correlation with each index for all years,whereas exception is observed for Gold.In addition,diversification between Bitcoin and Gold is demonstrated as well,mainly for short-term investments.However,the diversification benefit is conditional for both Bitcoin and Gold under the recent pandemic and war crises.The findings remind investors and portfolio managers planning to incorporate Bitcoin into their portfolios as a diversification tool to be aware of the global geopolitical conditions and other uncertainty in considering their investment tools and durations.

关键词： Bitcoin Gold Wavelet Coherence Diversification

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

Polymetallaynes and Molecular Metallaynes Containing Platinum,Mercury and Gold for Optoelectronic and Magnetic Applications

引用

Chinese Journal of Chemistry 2023年第17期41卷 2159-2178页

作者： Chen Zhang Linli Xu Wai-Yeung Wong Departmentof Applied Biology and Chemical Technology The Hong Kong Polytechnic UniversityHung HomHong Kongchina

omprehensive Summary,Polymetallaynes are a promising branch of metallopolymers,in which the introduction of metal building blocks to organic conjugated backbones leads to their unique skeletons and versatile properties.Notably,the chemical structures,geometric configurations and functional properties in these organometallic systems can be adjusted flexibly by the appropriate selection of metal centers,auxiliary ligands,or bridging spacers.In recent years,both one-dimensional and two-dimensional polymetallaynes have attracted considerable attention owing to their excellent electronic,optical and magnetic properties.Furthermore,the studies on molecular metallaynes provide substantial insights for the exploration of the structure-property-activity relationships in these organometallic acetylide-containing systems.The recent research progress of polymeric and molecular metallaynes containing platinum,mercury and Gold is discussed in this article.A series of functional properties have been realized in these acetylide-containing compounds by the rational structural design and refined synthetic strategies,leading to their emerging applications including energy conversion,nonlinear optics,data storage and memory,as well as chemo/biosensing.

关键词： Polymetallayne Molecular metallayne Metallated graphyne Platinum Mercury Gold

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

Orogenic Gold Deposits:Mineralization Mechanism and Research Perspectives

引用

Journal of Earth Science 2023年第6期34卷 1758-1761页

作者： Shao-Yong Jiang Ying Ma De-Liang Liu Wen-Tian Li State Key Laboratory of Geological Processes and Mineral Resources School of Earth ResourcesCollaborative Innovation Center for Exploration of Strategic Mineral ResourcesChina University of GeosciencesWuhan 430074China

0 INTRODUCTION Gold has been historically functioned as a strategic commodity,serving as a hard currency for international reserves,and increasingly plays a pivotal role in modern electronic communications,aerospace,and other high-tech industries.A range of geological processes (e.g.,magmatic activity,regional metamorphism,tectonic event) can result in formation of different types of Gold deposits hosted in various through time.Based on tectonic background and genetic model,Gold deposits can be classified into orogenic-,porphyry-,epithermal-,Carlin-,IOCG-(iron-oxide copper-Gold)(IOCG),VMS-(volcanogenic massive sulfide),and SEDEX-(sedimentary exhalative) Gold types (Kerrich et al.,2000).

关键词： magmatic tectonic Gold

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

Kinetics and mechanism of propylene hydro-oxidation to acrolein on Au catalysts

引用

Nano Research 2024年第1期17卷 354-363页

作者： Wei Du Zhihua Zhang Nan Song Xuezhi Duan Xinggui Zhou State Key Laboratory of Chemical Engineering School of Chemical EngineeringEast China University of Science and TechnologyShanghai 200237China

Propylene epoxidation by H_(2)and O_(2)to propylene oxide(PO)over the Au-Ti bifunctional catalysts,as an ideal reaction for PO production,has attracted great interest.Revealing the mechanism of acrolein formation is of great importance for understanding the mechanism of molecular oxygen activation and the formation of hydroperoxo species on the Au sites.Here,we investigate the reaction mechanism of propylene oxidation to acrolein on the Au/uncalcined TS-1(Au/TS-1-B)catalyst through a combination of multiple characterization,H_(2)/D_(2)exchange,kinetics experiment,and modeling.The Ti sites are found to be non-essential to acrolein formation.Moreover,the acrolein formation on the Au/TS-1-B catalyst is confirmed to be promoted by H_(2)through hydroperoxo species formation,which includes two main steps:propylene dehydrogenation to*C_(3)H_(5)with the aid of*OOH species,and*C_(3)H_(5)oxidation by*OOH to acrolein.The latter step is determined to be the rate-determining step because the corresponding kinetics model gives the best description for experimental results.This work not only provides kinetics insights for the propylene hydro-oxidation to acrolein on the Au-Ti bifunctional catalysts,but also facilitates the rational design of Au catalysts with high activity and selectivity in the direct propylene epoxidation with H_(2)and O_(2).

关键词： kinetics mechanism Gold acrolein hydro-oxidation

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

Microbe-mediated sustainable bio-recovery of Gold from low-grade precious solid waste:A microbiological overview

引用

Journal of Environmental Sciences 2020年第3期32卷 47-64页

作者： Supriyanka Rana Puranjan Mishra Zularisam ab Wahid Sveta Thakur Deepak Pant Lakhveer Singh Faculty of Civil Engineering Technology Universiti Malaysia Pahang26300GambangKuantanPahangMalaysia Earth Resources and Sustainability Center(EARS) Universiti Malaysia Pahang26300GambangKuantanPahangMalaysia Separation and Conversion Technology Flemish Institute for Technological Research(VITO)Boeretang 200Mol2400Belgium

In an era of electronics,recovering the precious metal such as Gold from ever increasing piles of electronic-wastes and metal-ion infested soil has become one of the prime concerns for researchers worldwide.Biological mining is an attractive,economical and nonhazardous to recover Gold from the low-grade auriferous ore containing waste or soil.This review represents the recent major biological Gold retrieval methods used to bio-mine Gold.The biomining methods discussed in this review include,bioleaching,bio-oxidation,bio-precipitation,bio-flotation,bio-flocculation,bio-sorption,bio-reduction,bioelectrometallurgical technologies and bio accumulation.The mechanism of Gold biorecovery by microbes is explained in detail to explore its intracellular mechanistic,which help it withstand high concentrations of Gold without causing any fatal consequences.Major challenges and future opportunities associated with each method and how they will dictate the fate of Gold bio-metallurgy from metal wastes or metal infested soil bioremediation in the coming future are also discussed.With the help of concurrent advancements in high-throughput technologies,the Gold bio-exploratory methods will speed up our ways to ensure maximum Gold retrieval out of such low-grade ores containing sources,while keeping the Gold mining clean and more sustainable.

关键词： Gold Critical metals Bio-recovery Biomining Gold harvesting microbes

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

Au(Ⅰ)-Catalyzed 6-endo-dig Cyclizations of Aromatic 1,5-Enynes to 2-(Naphthalen-2-yl)anilines Leading to Divergent Syntheses of Benzo[α]carbazole, Benzo[c,h]cinnoline and Dibenzo[i]phenanthridine Derivatives

引用

Chinese Journal of Chemistry 2022年第1期40卷 46-52页

作者： Jiayue Fu Bingbing Li Xiugui Wang Qida Liang Xiaoshi Peng Lu Yang Tao Wan Xinxiu Wang Bin Lin Maosheng Cheng Yongxiang Liu Key Laboratory of Structure-Based Drug Design and Discovery(Shenyang Pharmaceutical University) Ministry of EducationShenyangLiaoning 110016China Wuya College of Innovation Shenyang Pharmaceutical UniversityShenyangLiaoning 110016China Institute of Drug Research in Medicine Capital of China BenxiLiaoning 117000China Liaoning Kangboshi Pharmaceutical Co. LTDAnshanLiaoning 114100China

A Gold(Ⅰ)-catalyzed 6-endo-dig cyclization of aromatic 1,5-enynes was developed to synthesize 2-(naphthalen-2-yl)anilines.The functional group tolerance of this cyclization was examined systematically and a possible mechanism was proposed.The derivatization of 2-(naphthalen-2-yl)aniline was carried out to facile access to benzo[α]carbazole,benzo[c,h]cinnoline and dibenzo[i]phenanthridine derivatives in a divergent way.

关键词： Gold Homogeneous catalysis 6-endo-dig Cyclization Heterocycles Divergent synthesis

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

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：