检索结果-南通市图书馆

Paleohydrological Changes in the Western Tibetan Plateau over the Past 16,000 years Based on Sedimentary Records of n-Alkanes and Grain Size

引用

Acta Geologica Sinica(English Edition) 2020年第3期94卷 707-716页

作者： wang mingda YANG Yaping ZHANG Jiawu HOU Juzhi Key Laboratory of Alpine Ecology Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China Key Laboratory of Western China’s Environmental System(Ministry of Education) College of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China CAS Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of SciencesBeijing 100101China

Both monsoons and westerlies have exerted influence on climate dynamics over the Tibetan Plateau(TP) since the last deglaciation, producing complex patterns of paleohydroclimatic conditions. Diverse proxy records are essential to forge a robust understanding of the climate system on the TP. Currently, there is a general lack of understanding of the response of inland lakes over the TP to climate change, especially glacier-fed lakes. Paleohydrological reconstructions of such lakes could deepen our understanding of the history of lake systems and their relationship to regional climate variability. Here we use records of n-alkanes and grain size from the sediments of Bangong Co in the western TP to reconstruct paleohydrological changes over the past 16,000 years. The Paq record(the ratio of non-emergent aquatic macrophytes versus emergent aquatic macrophytes and terrestrial plants) is generally consistent with the variations in summer temperature and precipitation isotopes. The changes in grain-size distributions show a similar trend to Paq but with less pronounced fluctuations in the early-middle Holocene. The new data combined with previous results from the site demonstrate that: 1) Bangong Co experienced relatively large water-level fluctuations during the last deglaciation, with a steadily high lake-level during the early-middle Holocene and a decreasing lake-level in the late Holocene;2) The lake level fluctuations were driven by both high summer temperatures via the melting water and monsoon precipitation. However, the dominant factor controlling lake level changed over time. The lake-level history at Bangong Co deduced from the n-alkanes and grain-size records reveals the past hydrological changes in the catchment area, and stimulates more discussion about the future of glacier-fed lakes under the conditions of unprecedented warming in the region.

关键词： lake level n-alkane Paq grain size Bangong Co Tibetan Plateau

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

Application of orthogonal design to the extraction and HPLC analysis of sedimentary pigments from lakes of the Tibetan Plateau

引用

Science China Earth Sciences 2016年第6期59卷 1195-1205页

作者： LIANG Jie LI Dong wang mingda ZHANG XinYu HOU JuZhi Key Laboratory of Tibetan Environment Changes and Land Surface Processes Institute of Tibetan Plateau ResearchChinese Academy of Sciences College of Earth Sciences University of Chinese Academy of Sciences Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education College of Chemistry and Chemical Engineering Ocean University of China Second Institute of Oceanography State Oceanic Administration Key Laboratory of Marine Ecosystem and Biogeochemistry State Oceanic Administration MOE Key Laboratory for Earth Surface Processes Peking University College of Urban and Environmental Sciences Peking University

Sedimentary pigments are useful proxy indicators of phytoplankton biomass, community structure, primary productivity and human influence in lacustrine and oceanic ecosystems. Pigments are relatively labile due to their complex chemical structures, which makes the extraction and analysis of sedimentary pigments challenging. In addition, it is important to select appropriate methods to study sedimentary pigments in regions which lack previous investigations. In this study, we adopted the L9（34） orthogonal design to develop methods of extraction and HPLC （high performance liquid chromatography） analysis of sedimentary pigments at two lakes on the Tibetan Plateau： meromictic lake-Dagze Co and dimictic lake-Jiang Co. The orthogonal design comprises 9 combinations of various parameters for extraction and HPLC analysis. The results show that the type and volume of solvent are the most important factors for pigment extraction, and the mobile phase and column selection are the most important for HPLC analysis. For the study sites, we found that the best methods to extract sedimentary pigments are as follows： the use of a mixture of acetone：methanol：water （80： 15：5, v：v：v） as the extraction solvent; sol- vent/sample ratio of 10 mL/g; sonication for 30 s and standing extraction for 6 h. The best methods for HPLC analysis are as follows： Zorbax Eclipse plus C8 column with mobile phase A, methanol：acetonitrile：0.25 M aqueous pyridine （50： 25：25, v ： v ： v） and mobile phase B, methanol： acetonitrile： acetone （20： 60： 20, v： v： v）; pH of mobile phase A adjusted to 6 with acetic acid; and HPLC column temperature maintained at 40~C. The study provides an experimental basis for future investigations of past changes in primary productivity and the response of lake ecosystems to climate change and human activities on the Tibetan Plateau.

关键词： Tibetan Plateau Sedimentary pigments Pigment extraction Pigment analysis Orthogonal design

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

Holocene climate changes and paleoecology on the Tibetan Plateau:recent advances

引用

Frontiers of Earth Science 2023年第4期17卷 899-904页

作者： Juzhi HOU Xianyong CAO Duo WU mingda wang Group of Alpine Paleoecology and Human Adaptation State Key Laboratory of Tibetan Earth SystemResources and EnvironmentInstitute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China MOE Key Laboratory of Western China’s Environmental Systems College of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China School of Geographical Sciences Liaoning Normal UniversityDalian 116029China

*** Tibetan Plateau(TP)is the largest and highest terrain on the Earth,comprising more than 80%of continents higher than 4000 m above sea *** extremely high elevation resulted in cold and arid climate,sparse vegetation,limited available water resources,thin oxygen on TP,as well as desolated landscape,which makes it one of the most unfriendly habitable places on the ***,ancient humans lived on TP as early as 200 thousand years ago(Chen et al.,2019;Zhang et al.,2020),and developed ancient civilizations,including the Tibetan Empire,Guge Kingdom in historical periods.

关键词： Tibetan Plateau landscape

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

Alternating influences of the Westerlies and Indian Summer Monsoon on the hydroclimate of the source region of the Yarlung Tsangpo over past 4000 yr

引用

Frontiers of Earth Science 2023年第4期17卷 933-944页

作者： Zhe SUN Zirui HUANG Kejia JI mingda wang Juzhi HOU Institute of Geography and Resources Science Sichuan Normal UniversityChengdu 610066China Group of Alpine Paleoecology and Human Adaptation(ALPHA) State Key Laboratory of Tibetan Plateau Earth SystemResources and Environment(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China CAS Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of Sciences(CAS)Beijing 100101China School of Geography Liaoning Normal UniversityDalian 116029China

The Yarlung Tsangpo,the longest river in the southern Tibetan Plateau(TP),has attracted much research attention aimed at understanding the factors controlling its modern hydrology and possible future discharge in the context of ongoing climate ***,partly due to the complex regional climatic background,no consistent conclusions have been reached,especially for its upper *** reconstructions of the source region of the Yarlung Tsangpo can potentially improve our understanding of the history of humidity and its response to climatic *** this study,we used a 97 cm gravity core from Gongzhu Co to reconstruct the hydrology change during the late *** core was dated using AMS ^(14)C and Pb/Cs methods,and we used measurements of element contents(determined by high-resolution XRF scanning),grain size,IC/TOC,and magnetic susceptibility to reconstruct hydroclimatic changes in the source of the Yarlung Tsangpo watershed since~4000 yr *** with a modern meteorological data set,we found that PC1 of the XRF data,the Ca/(Fe+Ti)ratio,and EM1 of the grain size data were indicative of changes in *** records demonstrate a wet interval during~4-1.7 ka BP(ka=1000 yr,BP represents years before 1950 AD),followed by a dry period during since~1 ka *** with independent regional paleoclimatic records revealed shifts in the dominant factors controlling *** wet interval during~4-1.7 ka BP was coeval with a strengthened Westerlies,implying a dominant moisture supply from northern high ***,the extremely low values of Ca/(Fe+Ti)ratio during~4-2.5 ka BP indicate potential glacial freshwater source,which is corroborated by the concurrent high magnetic susceptibility values and increased grain *** rapid drying trend during~1.7-1 ka BP suggests a switch in moisture supply from the Westerlies to the Indian Summer Monsoon(ISM).We attribute the drought conditions after~1 ka BP to a weakened ISM,althoug

关键词： late Holocene humidity changes Westerlies ISM Yarluang Tsangpo

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 re-evaluation of the average chain length of lacustrine sedimentary n-alkanes as a paleoproxy on the Qinghai-Tibet Plateau

引用

Frontiers of Earth Science 2023年第4期17卷 905-919页

作者： mingda wang Qin LI Jaime TONEY David HENDERSON Juzhi HOU School of Geography Liaoning Normal UniversityDalian 116029China Alpine Paleoecology and Human Adaptation(ALPHA)Group State Key Laboratory of Tibetan Plateau Earth SystemResources and EnvironmentInstitute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China School of Geographical and Earth Sciences University of GlasgowGlasgow G128QQScotlandUK CAS Center for Excellence in Tibetan Plateau Earth Sciences Beijing 100101China

Long-chain n-alkanes are one of the most common organic compounds in terrestrial plants and they are well-preserved in various geological archives.n-alkanes are relatively resistant to degradation and thus they can provide high-fidelity records of past vegetation and climate ***,previous studies have shown that the interpretation of n-alkane proxies,such as the average chain length(ACL),is often ambiguous since this proxy depends on more than one *** vegetation and climate could exert controls on the n-alkane ACL,and hence its interpretation requires careful consideration,especially in regions like the Qinghai-Tibet Plateau(QTP)where topography,biome type and moisture source are highly *** further evaluate the influences of vegetation and climate on the ACL in high-elevation lakes,we examined the n-alkane distributions of the surface sediments of 55 lakes across the *** results show that the ACL across a climatic gradient is significantly affected by precipitation,rather than by *** positive correlation between ACL and precipitation may be because of the effect of microbial degradation during ***,we suggest that more caution is needed in the interpretation of ACL data in different regions.

关键词： ACL average chain length n-alkanes leaf wax lake sediments Qinghai-Tibet Plateau

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

Vegetation stability during the last two centuries on the western Tibetan Plateau:a palynological evidence

引用

Frontiers of Earth Science 2023年第4期17卷 1049-1058页

作者： Yanrong ZHANG Nannan wang Lina LIU mingda wang Xiaoshan YU Xianyong CAO Alpine Paleoecology and Human Adaptation Group(ALPHA) State Key Laboratory of Tibetan Plateau Earth SystemEnvironment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Science Beijing 100049China School of Geography Liaoning Normal UniversityDalian 116029China

Investigating the dynamics of vegetation is an essential basis to know how to protect ecological environments and to help predict any changes in *** of its fragile alpine ecosystem,the Tibetan Plateau is a particularly suitable area for studying vegetation changes and their driving *** this study,we present a high-resolution pollen record covering the last two centuries extracted from Gongzhu Co on the western Tibetan *** steppe is the predominant vegetation type in the surrounding area throughout the past 250 years with stable vegetation composition and abundance,as revealed by pollen spectra dominated by Artemisia,Ranunculaceae,Cyperaceae,and *** canonical correspondence analysis(DCCA)of the pollen data reveals low turnover in compositional species(0.41 SD),suggesting that the vegetation in the Gongzhu catchment had no significant temporal change,despite climate change and population increases in recent *** additionally ran DCCA on ten other pollen records from the Tibetan Plateau with high temporal resolution(1-20 years)covering recent centuries,and the results also show that compositional species turnover(0.15-0.81 SD)is relatively low,suggesting that the vegetation stability may have prevailed across the Tibetan Plateau during recent *** high-resolution pollen records and high taxonomic-resolution palaeo-vegetation records(such as sedaDNA),however,are needed to confirm the vegetation stability on the Tibetan Plateau.

关键词： pollen compositional 1species turnover vegetation change ecological stability

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

Application of Functionalized N,S-Ketene Acetals Microwave- Assisted Three-Component Domino Reaction for Rapid Direct Access to Imidazo[1,2-a]pyridines

引用

Chinese Journal of Chemistry 2013年第8期31卷 1033-1038页

作者： Li, Ming Li, Tengfei Zhao, Kelong wang, mingda Wen, Lirong Qingdao Univ Sci & Technol Coll Chem & Mol Engn Qingdao 266042 Shandong Peoples R China

Imidazo[1,2-a]pyridines have been successfully synthesized in moderate to good yields via a tandem three- component reaction of ethyl 2-（3-oxo-3-arylpropanethioamido）acetates with aromatic aldehydes and malononitrile by means of microwave irradiation using DABCO as the catalyst. The advantages of this method including high chemo- and regioselectivity make this new strategy highly attractive.

关键词： imidazo[1,2-a]pyridines N,S-ketene acetals multicomponent reaction domino reaction microwaveirradiation

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

A synergetic strategy of NIR-Ⅱ squaraine dyes with ultrahigh photothermal conversion efficiency for photothermal therapy

引用

Science China Chemistry 2024年第2期67卷 612-621页

作者： Yigang wang Guomin Xia Junhui wang mingda wang Weihan Guo Manman Tan Leilei Si Yang Yang Hua wang Hongming wang Institute for Advanced Study and School of Chemistry and Chemical Engineering Nanchang UniversityNanchang330031China State Key Laboratory of Molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian116023China The Second Affiliated Hospital of Nanchang University Nanchang330031China

Recent research on photothermal therapy(PTT) has sparked significant interest in the development of new organic photothermal agents(PTAs),ranging from single-molecule to aggregated ***,controlling aggregation pathways for PTAs with ultrahigh photothermal conversion efficiency(PCE) remains a major ***,a two-pronged approach utilizing “Haggregation” and “intramolecular motion” was employed to enhance the PCE of an acceptor-substituted squaraine dye(NSQs).The C2vmolecular symmetry of the NSQs,which possess a ground state dipole moment(μg),promotes H-dimeric aggregates through dipole-dipole *** triphenylethylene or diphenylamine groups were added to this H-dimeric *** was done to enhance intramolecular motions for heat generation and also to extend conjugation,which redshifted the optical absorption and balanced the blue-shift induced by *** this technique,an organic PTA with NIR-II absorption was developed,and its nanoparticle achieved a remarkable PCE of 86.3% under 1,064 nm laser *** transient absorption spectroscopy and quantum mechanical calculations demonstrated the accelerated internal conversion process in NIR-II PTAs for rapid heat *** NSQs nanoparticles exhibit superior photothermal therapeutic properties for in vivo photoacoustic imaging-guided PTT,demonstrating the potential of bottom-up design to enable synergistic engineering strategies towards efficient phototheranostic agents.

关键词： squaraine dyes second near-infrared window H-aggregation intramolecular motion photothermal therapy

来源：

维普期刊数据库

同方期刊数据库

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

Lacustrine Record of 1954 Flood Event on Begnas and Rupa Lake, Central Nepal

引用

Acta Geologica Sinica(English Edition) 2020年第3期94卷 717-724页

作者： Sudip ACHARYA LI Can-Ge JI Kejia SUN Zhe wang mingda HOU Juzhi Key Laboratory of Alpine Ecology Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China CAS Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of SciencesBeijing 100101China

In recent decades, there have been discussions and predictions regarding the impact of climate on floods, due to its socioeconomic and environmental consequences. For accurate prediction of future flood events and their impacts, it is crucial to have an improved understanding on past flood events. Lacustrine sediments have been used as a natural archive to study the past flood events. Here, we study the impact of 1954 flood event on the lacustrine environment of Bengas and Rupa Lake in central Nepal based on X-ray fluorescence spectrometry(XRF) element analysis, magnetic susceptibility(MS), total organic carbon(TOC) and the biomarker molecular compositions. Results showed that 1954 flood event had significant impacts on the two lakes in terms of detrital input, organic matter deposition and aquatic production. Before the flood event, both two studied lakes had relatively lower catchment erosion rate, lower organic matter deposition and aquatic production. During the flood event, catchment erosion and aquatic production increased in both lakes due to mass transport deposits and the increased nutrition loading attributed to flood event. Following the flood event, Begnas Lake showed the sharp increase in organic matter deposition, whereas in the Rupa Lake organic matter deposition showed minor changes. The difference in organic matter deposition in lakes during flooding event is likely due to detrital material brought and deposited by the flood activity. Overall our results suggest that lacustrine sediments are sensitive to the extreme event and would be an ideal archive for the reconstruction of flood events.

关键词： flood lacustrine environment Begnas Lake Rupa Lake Central Nepal

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

Minimally invasive liver resection in metabolic syndrome: insights and future directions

引用

Hepatobiliary Surgery and Nutrition 2024年第4期13卷 703-705页

作者： Kechun wang Yifan Li Jinbo Gong mingda wang Tian Yang Department of Hepatobiliary Surgery Eastern Hepatobiliary Surgery HospitalSecond Military Medical University(Naval Medical University)ShanghaiChina Department of Hepatobiliary Surgery Affiliated Hospital of Nantong UniversityNantongChina

Hepatocellular carcinoma(HCC)has emerged as a formidable global health challenge since it ranks the sixth most common malignant tumor and the third most common cause of cancer-related death(1).One of the most important factors in the creation of the increased incidence of HCC is the increasing rate of metabolic syndrome(MS),which is a complex interaction of metabolic abnormalities represented by obesity,insulin resistance,dyslipidemia,and *** was believed that chronic hepatitis B and C were one of the major etiologies of HCC,but additionally,the changed landscape of etiology now points toward MS and its comorbidities,such as non-alcoholic fatty liver disease,as major contributors in promotion of development and progress of HCC(2,3).

关键词： Minimally invasive surgery hepatectomy metabolic syndrome(MS) survival

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：