检索结果-南通市图书馆

Journal of Earth Science 2024年第5期35卷 1426-1446页

作者： Jintao Kong Zhongjie Xu Rihui Cheng duo wan College of Earth Sciences Jilin UniversityChangchun 130061China Key Laboratory of Mineral Resources Evaluation in Northeast Asia Ministry of Natural and ResourcesChangchun 130061China

During the Late Paleozoic-Early Mesozoic Era,the sediment transport system and tectonic regime in the southeastern margin of the South China Block(SESCB)all changed,significantly affected by the Paleo-Pacific ***,controversy exists about the Paleo-Pacific subduction's initiation *** study uses detrital zircon U-Pb ages to discuss the Late Triassic source-tosink system in the *** provides some references for the Paleo-Pacific subduction process based on crucial age information and zircons'trace *** paleogeography and similarity of detrital zircon age distribution indicate that three sinks were found in the SESCB during the Late Triassic:*** Yangchun-Kaiping-Gaoming area,comprising major age ranges of 260-220,460-400,and 1200-800 Ma,which might be sourced from the Yunkai terrane;*** Jiexi-Kanshi-Nanjing area,characterized by the significant age component of 2000-1800 Ma,which corresponded to the Wuyi terrane;*** Xinan area,consisting of significant age groups of 290-250 and 380-320 Ma,which might be sourced from the magmatic rocks formed by the Huinan Movement and Paleo-Pacific *** that 290-250 Ma zircons were widely distributed in the Upper Triassic strata,and their trace elements suggested the existence of a magmatic arc near the SESCB during the 290-250 ***,we propose that the Paleo-Pacific subduction might have begun in the Early Permian.

关键词： detrital zircon geochronology South China Block Paleo-Pacific Block provenance analysis geochronology geochemistry

Effects of substitution of group-V atoms for carbon or silicon atoms on optical properties of silicon carbide nanotubes

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2021年第6期30卷 602-609页

作者： Ying-Ying Yang Pei Gong wan-duo Ma Rui Hao Xiao-Yong Fang Key Laboratory for Microstructural Material Physics of Hebei Province School of ScienceYanshan UniversityQinhuangdao 066004China

Silicon carbide nanotubes(SiCNTs) have broad application prospects in the field of micro-nanodevices due to their excellent physical properties. Based on first-principles, the difference between optical properties of SiCNTs where C atom or Si atom is replaced by group-V element is studied. The results show that the optical absorptions of SiCNTs doped by different elements are significantly different in the band of 600 nm–1500 nm. The differences in photoconductivity, caused by different doping elements, are reflected mainly in the band above 620 nm, the difference in dielectric function and refractive index of SiCNTs are reflected mainly in the band above 500 nm. Further analysis shows that SiCNTs doped with different elements change their band structures, resulting in the differences among their optical properties. The calculation of formation energy shows that SiCNTs are more stable when group-V element replaces Si atom, except N atom. These research results will be beneficial to the applications of SiC nanomaterials in optoelectronic devices and provide a theoretical basis for selecting the SiCNTs' dopants.

关键词： silicon carbide nanotubes group-V doped optical properties first-principles theory

Conductance and dielectric properties of hydrogen and hydroxyl passivated SiCNWs

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2021年第10期30卷 609-616页

作者： wan-duo Ma Ya-Lin Li Pei Gong Ya-Hui Jia Xiao-Yong Fang Key Laboratory for Microstructural Material Physics of Hebei Province School of ScienceYanshan UniversityQinhuangdao 066004China

Based on the transport theory and the polarization relaxation model,the effects of hydrogen and hydroxyl passivation on the conductivity and dielectric properties of silicon carbide nanowires(SiCNWs)with different sizes are numerically *** results show that the variation trend of conductivity and band gap of passivated SiCNWs are opposite to the scenario of the size effect of bare *** the influencing factors of conductivity,the carrier concentration plays a leading *** the dielectric properties,the bare SiCNWs have a strong dielectric response in the blue light region,while passivated SiCNWs show a more obvious dielectric response in the far ultraviolet-light *** particular,hydroxyl passivation produces a strong dielectric relaxation in the microwave band,indicating that hydroxyl passivated SiCNWs have a wide range of applications in electromagnetic absorption and shielding.

关键词： silicon carbide nanowires passivation conductance properties dielectric relaxation

Age,Genesis,and Tectonic Setting of the Mo-W Mineralized Dongshanwan Granite Porphyry from the Xilamulun Metallogenic Belt,NE China

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2017年第3期28卷 433-446页

作者： Xuebing Zhang Keyong wang Chengyang wang Wen Li Qi YU Yicun wang Jianfeng Li duo wan Guanghuan Huang College of Earth Sciences Jilin UniversityChangchun 130061China Department of Earthquake Seienee Institute of Disaster Prevention Science and TechnologyBeijing 101601China Inner Mongolia Shandong Gold Minerals Survey Co.Ltd. Chifeng 024005China Heilongjiang Institute of Regional Geology Survey Harbin 150080China College of Urban and Environmental Sciences Liaoning Normal UniversityDalian 116029China

The Xilamulun molybdenum polymetallic metallogenic belt in eastern Inner Mongolia forms one of the most important Mo metallogenic belts in northeastern China. The Dongshanwan porphyry Mo-W polymetallic deposit, in the northeastern part of the Xilamulun metallogenic belt, occurs along the periphery of a granite porphyry and consists of Mo-W-Ag sulfide and oxide disseminations and veinlets in hydrothermal assemblages. LA-ICP-MS zircon U-Pb dating of the Dongshanwan granite porphyry yields a crystallization age of 142.15± 0.91 Ma, whereas molybdenite Re-Os isotopic dating model ages are of 139.9–141.5 Ma and an isochron age is of 140.5± 3.2 Ma（MSWD=1.2）. The age consistency indicates that the Dongshanwan deposit was a product of Early Cretaceous magmatism. The Dongshanwan granite porphyry is a high-alkali high-potassium intrusion and has high SiO_2（75.39 wt.%–76.15 wt.%）, low Al_2O_3（12 wt.%–13 wt.%）, Ba, Ti, P, and Sr contents, with negative Eu anomalies. The Y/Nb ratios are comparable to those of average continental crust and island arc basalts, corresponding to type-A2 granites. Our geochemical data indicate that the granite porphyry emplaced in an Early Cretaceous post-orogenic extensional environment following Mongol-Okhotsk oceanic subduction and subsequent continental collision.

关键词： Dongshanwan porphyry Mo-W deposit zircon U-Pb dating Re-Os dating geochemistry Xilamulun metallogenic belt

Provenance of Upper Jurassic in North Yellow Sea Basin， Eastern North China Craton

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2024年

作者： Haitian Yu Zhongjie Xu Rihui Cheng duo wan Dan Gao Zhen Zhang Key Laboratory of Mineral Resources Evaluation in Northeast Asia， Ministry of Natural Resources College of Palaeontology， Shenyang Normal University Guangzhou Marine Geological Survey

Base on the detrital zircon U-Pb dating data， this paper discusses the provenance and constructs source-to-sink system of the Upper Jurassic in the North Yellow Sea Basin (NYSB)， Eastern North China Craton (ENCC). In addition， to avoid the bias of detrital zircon ages caused by variations in zircon fertility， we gather 1709 whole rock zirconium content values (ppm) from granitic rocks with different ages in the North China Craton (NCC). Base on mean Zr content of granitic rocks in each age， these granitic rocks can be divided into four groups: Group A consists of Jurassic， Group B consists of Paleozoic， Neo-Mesoproterozoic and Neoarchean， Group C consists of Early Cretaceous and Triassic， and Group D consists of Paleoproterozoic. This research assigns these groups zircon fertility factors (ZFF) of 1， 1.4， 1.8 and 2.2. The U-Pb age of detrital zircons from Late Jurassic sediments corrected by ZFF are statistically analyzed (K-S test， Similarity， Cross-correlation， Linkeness， Multidimensional scaling). And combining with palaeocurrent and palaeogeography， we construct two source-to-sink systems: 1) Jiaodong Uplift and Sulu Orogenic belt as the source area and the North Yellow Sea Basin as the sink area; 2) Liaodong Peninsula as the source area and the North Yellow Sea Basin as the sink area.

关键词：

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

阴极材料组织对铝电解钠渗透过程的影响

材料热处理学报 2014年第7期35卷 146-150页

作者：王维谷万铎河南科技大学材料科学与工程学院河南洛阳471023 有色金属共性技术河南省协同创新中心河南洛阳471023 伊川电力集团总公司河南伊川471312

为了研究工业中使用阴极碳块钠和电解质的渗透过程,用扫描电子显微镜和酚酞试剂法研究铝电解后阴极试样碳块(35%半石墨质、全石墨质和石墨化)钠和电解质的渗透行为。结果表明,阴极材料内部孔隙连通越多,NaF与Na3AlF6在阴极碳块中的浓度... 详细信息

为了研究工业中使用阴极碳块钠和电解质的渗透过程,用扫描电子显微镜和酚酞试剂法研究铝电解后阴极试样碳块(35%半石墨质、全石墨质和石墨化)钠和电解质的渗透行为。结果表明,阴极材料内部孔隙连通越多,NaF与Na3AlF6在阴极碳块中的浓度越高;阴极碳块石墨化程度越高,渗透到阴极碳块的钠和电解质浓度越低。但钠在3种阴极碳块骨料石墨的"微孔"中渗透量几乎没有差别。

关键词：碳素阴极组织结构石墨化程度钠渗透

铝电解碳素阴极材料在高温和电解状态下的蠕变模型

在线全文

学校读者我要写书评

暂无评论

中国有色金属学报 2014年第9期24卷 2339-2344页

作者：王维逯峙谷万铎河南科技大学材料科学与工程学院洛阳471023 有色金属共性技术河南省协同创新中心洛阳471023 伊川电力集团总公司伊川471312

为了获取铝电解碳素阴极材料的蠕变数据和Burgers模型参数,在965℃及电解状态下,对现行工业中使用的3种铝电解碳素阴极材料(半石墨质、全石墨质和石墨化)进行单轴压缩蠕变实验,采用Burgers模型对阴极材料黏弹性行为进行分析。利用Origin... 详细信息

为了获取铝电解碳素阴极材料的蠕变数据和Burgers模型参数,在965℃及电解状态下,对现行工业中使用的3种铝电解碳素阴极材料(半石墨质、全石墨质和石墨化)进行单轴压缩蠕变实验,采用Burgers模型对阴极材料黏弹性行为进行分析。利用Origin8.5软件对Burgers模型参数进行拟合,得到碳素阴极材料的黏弹性方程。结果表明:Burgers模型能较好地反映碳素阴极材料在单轴压缩应力作用下的黏弹特性,阴极材料石墨化程度越高,Burgers模型参数E1、E2、η2和η1值越大,材料的抗蠕变能力越强。在电解过程中,钠和电解质破坏阴极材料结构,Burgers模型参数E1、E2、η2和η1值变小,材料的抗蠕变能力变差。所获结果可为掌握阴极材料在外力作用下的蠕变规律、实现对电解槽生产运行过程中阴极变形的调控和电解槽寿命预测提供技术参考。

关键词：铝电解碳素阴极材料蠕变 Burgers模型

在线全文

学校读者我要写书评

暂无评论

铝土矿山生态环境保护措施

轻金属 2008年第5期 5-8页

作者：万多稳云南文山铝业有限公司云南昆明650502

铝矿山露天开采对生态环境影响较大,本文通过分析云南省文山铝土矿开发对生态环境影响因素,分析铝矿生态环境保护措施,采用"剥离—采矿—复垦"一体化工艺,采矿和复垦同时进行,改善植被立地条件,矿区的水土流失可得到控制和削减,生态环... 详细信息

铝矿山露天开采对生态环境影响较大,本文通过分析云南省文山铝土矿开发对生态环境影响因素,分析铝矿生态环境保护措施,采用"剥离—采矿—复垦"一体化工艺,采矿和复垦同时进行,改善植被立地条件,矿区的水土流失可得到控制和削减,生态环境得到很好的恢复和改善,实现矿山开发的生态文明。

关键词：矿山生态环境水土流失复垦水土保持

在线全文

学校读者我要写书评

暂无评论

基于粒子群优化的频域多信道干扰对齐算法

北京邮电大学学报 2016年第3期39卷 22-26页

作者：邹卫霞王多万杜光龙北京邮电大学泛网无线通信教育部重点实验室北京100876 东南大学毫米波国家重点实验室南京210096

针对频域干扰对齐系统解空间的多峰值特性,提出了一种基于粒子群优化,以系统网络和速率为优化目标函数的干扰对齐全局搜索算法.该算法通过对速度向量在位置向量的法平面上做投影以加强全局搜索能力,并在粒子群标准位置更新的基础上增加... 详细信息

针对频域干扰对齐系统解空间的多峰值特性,提出了一种基于粒子群优化,以系统网络和速率为优化目标函数的干扰对齐全局搜索算法.该算法通过对速度向量在位置向量的法平面上做投影以加强全局搜索能力,并在粒子群标准位置更新的基础上增加沿目标函数梯度方向的学习搜索来提高算法收敛速度和趋向全局最优值的能力.数值仿真结果表明,该算法可以获得比现有算法更好的网络和速率性能.

关键词：干扰对齐频域多信道自由度粒子群优化梯度网络和速率

中国蔬菜出口贸易格局演变及其影响因素研究——基于社会网络方法

在线全文

学校读者我要写书评

暂无评论

经济问题 2024年第3期 23-29页

作者：万多许月艳浙商银行太原分行山西太原030000 华中农业大学经济管理学院湖北武汉430070

基于社会网络学方法构建了中国蔬菜出口贸易网络,并分析了中国蔬菜出口贸易网络格局的演变特征及其影响因素。研究结果表明:中国蔬菜出口贸易网络规模逐渐扩大,网络中各国间的贸易联系日益密切,中国在网络中占据出口中心地位,但网络影... 详细信息

基于社会网络学方法构建了中国蔬菜出口贸易网络,并分析了中国蔬菜出口贸易网络格局的演变特征及其影响因素。研究结果表明:中国蔬菜出口贸易网络规模逐渐扩大,网络中各国间的贸易联系日益密切,中国在网络中占据出口中心地位,但网络影响力和控制力还有待增强;中国蔬菜出口贸易网络的社团分布发生了较大变化,到2020年,以中国、俄罗斯等国家为核心的贸易社团成长为规模最大的蔬菜贸易社团;劳动力资源禀赋、经济因素、政策及地理文化因素均对中国蔬菜出口贸易网络具有显著影响。

关键词：蔬菜出口贸易社会网络二次指派程序