检索结果-南通市图书馆

Chinese Geographical Science 2010年第3期20卷 243-251页

作者： LU Yingxia LI Baosheng WEN Xiaohao QIU Shifan wang fengnian NIU Dongfeng LI Zhiwen Geography Department South China Normal University Guangzhou 510631 China State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi'an 710061 China Guangzhou lnstitute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 China

The upmost segment （Holocene series） of the Milanggouwan stratigraphic section （MGS 1） in the Salawusu River valley shows 11 sedimentary cycles of dune sands and fluvio-lacustrine facies, or dune sands and paleosols. The analysis of the magnetic susceptibility of this segment suggests that there are 11 magnetic susceptibility cycles with the value alternating from low to high, in which the layers of the dune sands correspond to the lower value of the magnetic susceptibility and the layers of fluvio-lacustrine facies and paleosols correspond to the higher peaks. The study reveals that the low and high magnetic susceptibility values indicate the climate dominated by cold-arid winter monsoon and warm-humid summer monsoon of East Asia, respectively, and the study area has experienced at least 22 times of milleunial-centennial scales climate alternation from the cold-arid to the warm-humid during the Holocene. In terms of the time and the climate nature, the variations basically correspond to those of the North Atlantic and some records of cold-warm changes in China as well. They might be caused by the alternation of winter and summer monsoons in the Mu Us Desert induced by global climate fluctuations in the Holocene.

关键词： MGS1 segment magnetic susceptibility millennial-centennial scales climate changes Holocene Salawusu River valley

Grain-size Characteristics and Climate Variability in TMS5e Sequence of Tumen Section in Southern Tengger Desert,Northwestern China

在线全文

学校读者我要写书评

暂无评论

Chinese Geographical Science 2012年第1期22卷 48-62页

作者： WEN Xiaohao LI Baosheng wang fengnian ZHENG Yanming NIU Dongfeng SI Yuejin OU Xianjiao School of Geographical Science South China Normal University Guangzhou 510631 China State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi＇an 710075 China School of Geography and Planning Sun Yat-Sen University Guangzhou 510275 China School of Geography and Tourism Jiaying University Meizhou 514015 China

The TMS5e sequence from the Tumen section, at the southern edge of Tengger Desert in the northwestern China, is synchronous with Marine Isotope Stage 5e （MIS5e）. It consists of 16 layers of aeolian dune sands, 11 layers of lacustrine loess-like facies, and 5 layers of lacustrine facies. The results of grain-size analysis shows that the pa- laeo-mobile dune sands, palaeo-fixed to semi-fixed dune sands and loess-like sandy loams are mainly composed of sands, ranging from 70% to 96%; their silt contents ranged from 4% to 20%, and their clay contents ranged from 1% to 5%; the climate under which the aeolian dune sands were deposited is similar to that under which modern mobile dune sands form, which is caused by the dominance of the cold, dry East Asian winter monsoon. In contrast, the lacustrine loess-like facies and lacustrine facies had a lower sand contents than those of the three aeolian dune sands, but have higher silt and clay contents, most of their sand content ranged from 30% to 60%, their silt contents ranged from 35% to 55%, and their clay contents ranged from 6% to 20%. The lacustrine loess-like facies and lacustrine facies formed under the influence of the warm, humid East Asian summer monsoon based on their similarity with modern sediments. The grain-size indicator Mz （mean grain diameter） and the SC/D value in the TMS5e sequence indicate climatic insta- bility at the southern edge of the Tengger Desert during MIS5e, with at least 14 fluctuations between a warm, humid climate and a cold, dry climate, divided into five stages： TMS5e5 （139 kyr to 129.3 kyr B.P.）, TMS5e4 （129.3 kyr to 124 kyr B.P.）, TMS5e3 （124 kyr to 119.5 kyr B.P.）, TMS5e2 （119.5 kyr to 116.5 kyr B.P.）, and TMS5el （116.5 kyr to 113.7 kyr B.P.）. These correspond roughly to MIS5e5, MIS5e4, MIS5e3, MIS5e2, and MIS5el, respectively, in the GRIP ice core data.

关键词： Tengger Desert Tureen section TMS5e sequence grain-size characteristics palaeoclimate reconstruction Marine Isotope Stage 5e (MIS5e)

Problems and Countermeasures in the Keywords of Academic Papers

在线全文

学校读者我要写书评

暂无评论

Journalism and Mass Communication 2019年第1期9卷 26-32页

作者： wang fengnian Tsinghua University Beijing China

Keywords with the retrieval value clearly show the main contents, enhance the influence of academic periodicals, highlight specific information, and generalize information, but because of the ignorance of the value of keywords from some authors and editors, the lack of canonical guidance, and limitations of the editorial knowledge structure, there are some problems concerning keywords in academic papers, such as papers containing too many or too few keywords, or keywords being used in a way that is too general or colloquial. According to academic principle, accurate principle, logical principle, comprehensive principle, it is imperative to discuss how to choose keywords properly.

关键词： keywords academic papers selection criteria of keywords countermeasures of keywords

The Predicaments and Countermeasures of the Chinese Commercial Bibliographic Databases

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

Journalism and Mass Communication 2017年第1期7卷 17-24页

作者： wang fengnian Tsinghua University Beijing China

In China, the vast majority of the bibliographic databases is commercial, such as China National Knowledge Infrastructure （CNKI）, Wanfang Database, Longyuan Journal Net, CQVIP Company, however, there are also non-profit open access （OA） databases, such as journal database jointly established by Chinese Academy of Social Sciences （CASS） and National Social Science Fund. The commercial bibliographic databases have to face many difficulties： intellectual property disputes, the benefit distribution between the hardcopy periodical and the commercial bibliographic database, the lack of quality assessment about the commercial bibliographic databases, the need of improving digital technology as well as the lack of a unified database regulation, which restricts the development of commercial bibliographic databases. This paper puts forward the countermeasures from the perspective of how to enhance the governmental management; how to protect the intellectual property fight; how to improve the technical standard of the commercial bibliographic databases; how to build interest distribution between the hardcopy periodical and the commercial bibliographic database; how to improve the quality of commercial bibliographic databases; and how to improve the industrial chain of the commercial bibliographic databases.

关键词： the commercial bibliographic databases the predicaments of the commercial bibliographic databases the strategies of the commercial bibliographic databases

Pleniglacial millennium-scale climate variations in northern China based on records from the Salawusu River Valley

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

Journal of Arid Land 2012年第3期4卷 231-240页

作者： fengnian wang BaoSheng LI JiangLong wang XiaoHao WEN DongFeng NIU ZhiWen LI YueJun SI YiHua GUO ShuHuan DU School of Geography South China Normal UniversityGuangzhou 510631China State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of SciencesXi'an 710061China Chenghai Middle School Shantou 510601China College of Earth Science East China Institute of TechnologyNanchang 330013China Key Laboratory of Marginal Sea Geology South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China

Situated in the Salawusu River Valley, southeast of China＇s Mu Us Desert, the MGS2 （Milanggouwan section） portion of the Milanggouwan stratigraphic section records 5.5 sedimentary cycles consisting of alternations between dune sand deposits and fluvial or lacustrine facies. We analyzed the grain-size and CaCO3 distributions in MGS2, and found that Mz （mean particle diameter） and o （standard deviation） displayed clear variations in peaks and valleys within different sedimentary facies. The CaCO3 content averaged 0.4% in the dune sand deposits, 1.43% in the fluvial facies, and 8.82% in the lacustrine facies. Both the grain-size distribution and CaCO3 contents, which equal the indicators for the alternation among the sedimentary facies, suggest the occurrence of 5.5 cycles. These results suggest that the observed cycles mainly resulted from fluctuations between a cold and dry winter monsoon climate and a warm and humid summer monsoon climate, and that the MGS2 portion experienced at least 5.5 fluctuations between these two extremes. This high-frequency climatic fluctuation indicates a strong influence of millennium-scale variations in the strength of the East Asian winter and summer monsoons in our study area during the Pleniglacial.

关键词： Salawusu River Valley Pleniglacial paleoclimatic indices CaCO3 grain-size

Current study and prospect of the Old Red Sand along the southeast coast of China

在线全文

学校读者我要写书评

暂无评论

Research in Cold and Arid Regions 2012年第6期4卷 462-471页

作者： ZhiWen Li YuXiang Dong BaoSheng Li fengnian wang College of Earth Sciences East China Institute of Technology Nanchang Geography and Planning School Sun Yat-sen University Guangzhou School of Geography South China Normal University Guangzhou State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Department of Tourism Huizhou University

The Old Red Sand is composed of brown-red, red, or orange-yellow semi-cemented and medium-fine sand sediment, mainly dis- tributed along the southeast coast of China. Based on previous studies, this paper summarizes the distribution and forms, sedi- mentary characteristics, formation mechanism, developing age, reddening process and the paleo-environment, suggesting that the Old Red Sand is mainly aeolian sediment of Late Pleistocene Age. The reddening process is mainly the result of decomposition and oxidation of iron-containing minerals caused by hot and humid tropical and sub-tropical climate. In this study, existing prob- lems are discussed and the prospect of further research is presented as well.

关键词： southeast coast of China Old Red Sand current study situation prospects

在线全文

学校读者我要写书评

暂无评论

太阳能热化学规模储热技术

科学通报 2024年第25期69卷 3689-3692页

作者：宋超车锦波王峰年王睿李印实西安交通大学能源与动力工程学院热流科学与工程教育部重点实验室西安710049 西安交通大学化学工程与技术学院西安710049

随着社会的发展,能源危机和环境问题日益突出,推动实现全球碳中和已成为国际社会的共同目标,世界各地正在进行深刻的能源结构改革,太阳能和风能等绿色能源逐渐占据主导地位. 2018年,全球能源系统中约有10%的电力来自可再生能源,根据国... 详细信息

随着社会的发展,能源危机和环境问题日益突出,推动实现全球碳中和已成为国际社会的共同目标,世界各地正在进行深刻的能源结构改革,太阳能和风能等绿色能源逐渐占据主导地位. 2018年,全球能源系统中约有10%的电力来自可再生能源,根据国际可再生能源署预测,到2030年,这一数值将增至35%,到2050年绿色能源将提供60%以上的全球发电量,成为未来能源供给的核心力量^([1]).然而,以太阳能为代表的绿色能源具有典型的低密度、波动性和难以稳定供应的特征,不利于能源供给与需求的实时匹配.

关键词：可再生能源绿色能源能源危机太阳能热化学储热技术能源结构碳中和能源供给

广西北部湾海岸风沙记录的千年来风暴潮演化的阶段性

在线全文

学校读者我要写书评

暂无评论

地理学报 2022年第5期77卷 1181-1194页

作者：司月君李保生王丰年杜恕环牛东风南宁师范大学北部湾环境演变与资源利用教育部重点实验室/地理科学与规划学院南宁530001 中国科学院地球环境研究所黄土与第四纪地质国家重点实验室西安710061 华南师范大学地理科学学院广州530631 惠州学院惠州516007 中国科学院南海海洋研究所边缘海与大洋地质重点实验室广州510301 岭南师范学院湛江524048

本文以广西防城港市江平镇巫头剖面(21°32′8.25″N,108°06′59.9″E)晚全新世厚393 cm含风暴沉积层的风成沙—潟湖相—弱成壤沉积序列为研究对象,结合野外观测的风暴层沉积特点,在6个AMS-14C、OSL测年数据和沉积物粒度、重矿物分析... 详细信息

本文以广西防城港市江平镇巫头剖面(21°32′8.25″N,108°06′59.9″E)晚全新世厚393 cm含风暴沉积层的风成沙—潟湖相—弱成壤沉积序列为研究对象,结合野外观测的风暴层沉积特点,在6个AMS-14C、OSL测年数据和沉积物粒度、重矿物分析的基础上重建了广西北部湾沿海千年来风暴潮演化史。分析结果显示,风暴沉积层平均粒径粗、分选差,重矿物成熟度高、稳定度低,是海岸后滨沙丘向陆一侧受风暴潮增水影响快速堆积的产物;千年来巫头剖面记录的9个风暴潮高发期主要集中于1400 AD之后的小冰期内,风暴潮高发期与西太平洋SST、ENSO活动趋势呈反相关,其中一些风暴潮高发期和历史文献记录的4次“海溢”事件与太阳黑子活动曲线有近乎同步的变化趋势。这意味着巫头剖面风暴潮高发期除受西太平洋暖池、ENSO的影响外,可能还在相当程度上受到太阳活动的强迫。

关键词：千年来广西北部湾海岸风沙风暴潮粒度重矿物组合

在线全文

学校读者我要写书评

暂无评论

砂化白云岩变压力注浆扩散规律研究

岩石力学与工程学报 2024年第S01期43卷 3477-3490页

作者：杨柳姜晓宇陶志刚王丰年刘朝阳中国矿业大学(北京)深部岩土力学与地下工程国家重点实验室北京100083

为研究滇中引水工程玉溪施工段白云岩砂化对隧道注浆加固的影响,进而揭示浆液扩散规律,综合开展扫描电镜(SEM)试验、理论分析以及多物理场流固耦合数值模拟一系列深入研究。结果表明,白云岩在溶蚀作用下砂化且内部构造发育呈多尺度孔隙... 详细信息

为研究滇中引水工程玉溪施工段白云岩砂化对隧道注浆加固的影响,进而揭示浆液扩散规律,综合开展扫描电镜(SEM)试验、理论分析以及多物理场流固耦合数值模拟一系列深入研究。结果表明,白云岩在溶蚀作用下砂化且内部构造发育呈多尺度孔隙-裂隙网络体系分布特征,注浆时浆液扩散迁移的过程中存在前锋面并产生明显指进现象,发育构型不同的裂隙会导致水泥浆液扩散形态的不规则性和非稳定性。相比传统的恒压注浆,变压力梯度注浆更利于对砂化后地层复杂构造发育的多尺度裂隙进行均匀填充,浆液凝固后胶结破碎岩体减小围岩应力分布区域同时缓解拱顶、拱底的应力集中现象,对于提高围岩稳定性具有更加显著的效果。以上研究可为砂化白云岩地层隧道的实际注浆工程设计及施工提供理论参考。

关键词：岩石力学砂化白云岩滇中引水注浆扩散变压力梯度流固耦合

在线全文

学校读者我要写书评

暂无评论

均势视野下的朝核危机

内蒙古农业大学学报（社会科学版） 2007年第4期9卷 174-176页

作者：王丰年华南师范大学政治与行政学院广东广州510631

均势理论的历史源远流长,无论是在中国还是在西方历史中,它对于和平的实现和维持都起过非常重要的作用。朝鲜半岛一度因朝核危机而几近战争的边缘,朝鲜核问题事关东北亚地区的安全稳定以及与中、日、美、俄之间的大国关系,并成为大国利... 详细信息

均势理论的历史源远流长,无论是在中国还是在西方历史中,它对于和平的实现和维持都起过非常重要的作用。朝鲜半岛一度因朝核危机而几近战争的边缘,朝鲜核问题事关东北亚地区的安全稳定以及与中、日、美、俄之间的大国关系,并成为大国利益的交汇点。和平解决朝鲜核危机、维持均势是大国之间博弈的结果和各自利益的真实体现。

关键词：均势朝核危机利益