检索结果-南通市图书馆

Climate evolution of southwest Australia in the Miocene and its main controlling factors

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2022年第6期65卷 1104-1115页

作者： Tianqi SUN zhaokai XU Fengming chang Tiegang LI Key Laboratory of Marine Geology and Environment Institute of OceanologyChinese Academy of SciencesQingdao 266071China Laboratory for Marine Geology Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266061China University of Chinese Academy of Sciences Beijing 100049China CAS Center for Excellence in Quaternary Science and Global change Xi’an 710061China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China Key Laboratory of Marine Sedimentology and Metallogeny First Institute of OceanographyMNRQingdao 266061China

At present, the seasonal melting and expansion of the Antarctic ice sheet affect the location and intensification of the westerlies, as well as the precipitation and continental weathering and erosion in southwest Australia. The Miocene was an important period when the Earth's climate state transitioned from a warmhouse to an icehouse and the East Antarctic Ice Sheet underwent large-scale melting and expansion. At that time, Australia was closer to the Antarctic region than it is now. This makes Australia an ideal target area for studying the coupling relationship among the atmosphere, hydrosphere, lithosphere, and cryosphere. Based on the comprehensive analysis of the siliciclastic mass accumulation rate, grain size, clay minerals, and elemental composition of the sediments at Site U1516 of the International Ocean Discovery Program Expedition 369, we reconstructed the Miocene climate evolution and the continental weathering and erosion history of southwest Australia on a tectonic time scale. Our indicators show that the climate was dry and that continental weathering and erosion were weak, with a small amount of terrestrial material transported to the ocean during the Early to Middle Miocene(22–12.7 Ma). However, as mentioned in previous studies of nearby sites, precipitation and river runoff increased prominently with enhanced continental weathering at 12.7–8 Ma, which was related to the northward migration or intensification of the westerlies, possibly due to increased sea ice in the Southern Ocean. In addition, we found that the evolution of the South Asian monsoon and the westerly belt were synchronized in the Miocene, which indicates that the South Asian monsoon system at that time may also have been affected by the high-latitude signals of the Southern Hemisphere. We speculate that the significant decrease in deep-sea temperature and the expansion of the surface sea temperature gradient in latitude and longitude until the permanent East Antarctic Ice Sheet fo

关键词： Miocene Southwest Australia Climate evolution Controlling factors International ocean discovery program

Indole derivatives as agrochemicals:An overview

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第7期35卷 66-72页

作者： ping Sun Yuanqin Huang Shunhong Chen Xining Ma zhaokai Yang Jian Wu National Key Laboratory of Green Pesticide Key Laboratory of Green Pesticide and Agricultural BioengineeringMinistry of EducationGuizhou UniversityGuiyang 550025China

Indole is a biologically active compound formed by the fusion of benzene and pyrrole,and it is widely found in natural products and *** to the unique structure and properties of indole,its derivatives often exhibit distinctive physiological activities,which has led to widespread attention in the field of pesticide *** the design strategies and structure-activity relationships(SARs)of compounds is a crucial step in developing novel *** review mainly summarizes indole compounds with plant growth regulating,antiviral,fungicidal,herbicidal,and insecticidal activities,with the aim of providing new insights into the discovery and mechanism of action of novel indole-based pesticides.

关键词： Indole compounds Agrochemicals Biological activity Structure-activity relationship Mechanism of action

Geochemistry of rare earth elements in the mid-late Quaternary sediments of the western Philippine Sea and their paleoenvironmental significance

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2014年第4期57卷 802-812页

作者： XU zhaokai LI TieGang WAN ShiMing yin XueBo JIANG FuQing SUN HanJie JinYong CHOI DhongIl LIM Key Laboratory of Marine Geology and Environment Institute of OceanologyChinese Academy of Sciences Department of Oceanography Kunsan National University South Sea Institute Korea Institute of Ocean Science and Technology

Based on a δ180 chronology, rare earth elements （REE） and other typical elements in sediments from core MD06-3047 in the western Philippine Sea were analyzed to constrain the provenances of the sediments and investigate quantitative changes in the Asian eolian input to the study area over the last 700 ka. Among the competing processes that might affect REE compositions, sediment provenance is the most important one. Provenance analysis suggests that the study sediments have two provenance end-members; local volcanic sources are dominant, and eolian dust from the Asian continent has a smaller contribution. During glacial periods, eolian input to the western Philippine Sea was enhanced. In contrast, material supply from local volcanics in- creased during interglacial periods. changes in eolian input to the study area were probably related to the strength of the East Asian winter monsoon （EAWM） as well as aridity in the Asian continent on an orbital time scale, and were partly influenced by local control factors on shorter time scales. Therefore, we propose that the present study expands the application of the REE-based method for quantitatively estimating the eolian component from the mid-latitude northern Pacific to the low-latitude western Pacific. Additionally, the study preliminarily confirms the influence of EAWM-transported eolian materi- al on sedimentation in the western Philippine Sea since 700 ka.

关键词： eolian dust sediment provenance rare earth elements East Asian winter monsoon glacial/interglacial cycle western Philippine Sea

Optimizing signal collection efficiency of the VIPA-based Brillouin spectrometer

在线全文

学校读者我要写书评

暂无评论

Journal of Innovative Optical Health Sciences 2015年第4期8卷 39-45页

作者： zhaokai Meng Vladislav V.Yakovlev Texas A&M University College StationTX 77843USA

Brillouin spectroscopy is an emerging tool for microscopic optical imaging as it allows for non-invasive and direct assessment of the viscoelastic properties of *** advances of background-free confocal Brillouin spectrometer allows investigators to acquire the Brillouin spectra for turbid samples as well as transparent ***,due to strong signal loss induced by the imperfect optical setup,the Brillouin photons are usually immersed in background *** this report,we proposed and experimentally demonstrated multiple approaches to enhance the signal collction eficiency.A signal enhancement by>4 times can be observed,enabling ob-servation of ultra-weak signals.

关键词： Brillouin spectroscopy confocal microscope microscopic mechanical property specific imaging

Response of the northwestern Pacific upper water δ^(13)C to the last deglacial ventilation of the deep Southern Ocean

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

Chinese Science Bulletin 2011年第24期56卷 2628-2634页

作者： CHEN ShuangXi LI TieGang TANG Zheng QIU XiaoHua XIONG ZhiFang NAN QingYun XU zhaokai chang FengMing Key Laboratory of Marine Geology and Environment Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China Key Laboratory of Marine Hydrocarbon Resources and Environmental Geology Qingdao Institute of Marine Geology Ministry of Land and Resources of China Qingdao 266071 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

The deglacial δ~13C minimum events that originated from the ventilation of the deep Southern Ocean around Antarctica, have been recorded in a range of marine sediments from the southern to tropical oceans in late Pleistocene. However, the broad δ~13C minimum event was also reported as far as to the northern middle latitudes, in northwestern Pacific marginal sea areas, during the last deglaciation. In the northwestern Pacific, forcing from the northern high latitudes is strongly expressed, while the records of in- fluence from the southern high latitudes are few. The Kuroshio Source Region (KSR) forms a boundary between the northwestern Pacific and the southern, tropical Pacific. So, high-resolution planktonic foraminiferal records in core MD06-3054 from the KSR are well positioned to identify signals from the southern hemisphere in the northwestern Pacific. Planktonic foraminiferal tests from the upper 1030 cm of the core were subject to AMS14C, carbon and oxygen isotopic measurements. A negative excursion was found to occur from about 20.0-6.0 ka BP in δ~13C records of both surface (Globigerinoides ruber) and subsurface (Pulleni- atina obliquiloculata) dwellers, but the overall trends of the two curves have reversed since 26.5 ka BP. Moreover, the δ~13C rec- ord of G. ruber (the surface dweller) shows a robust link to the record of atmospheric CO2, and its changes precede the records of P. obliquiloculata (the subsurface dweller). According to the hydrologic conditions, the broad δ~13C minimum event recorded in the KSR is also a response to the increasing ventilation of the deep Southern Ocean around Antarctica during the last deglaciation. The inconsistency between the records of the surface and subsurface dwellers was possibly caused by the ways that the low δ~13C signal was transmitted. Subsurface water primarily received the low δ~13C signal from the Antarctic Intermediate Water (AAIW), whereas the surface water was probably mainly impacted by atmospheric CO2 i

关键词：西北太平洋边缘水文条件南大洋通风信号传输方式末次冰消期高纬度地区中纬度地区

Molecular phylogenetics of Gymnocypris (Teleostei: Cyprinidae) in Lake Qinghai and adjacent drainages

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2005年第13期50卷 1325-1333页

作者： zhaokai LIJunbing YANGGongshe DUANZiyuan HEShunping CHENYiyu InstituteofHydrobiology ChineseAcademyofSciencesWuhan430072China//AgricultureandAnimalHusbandryCollegeQinghaiUniversityXining810003China InstituteofHydrobiology ChineseAcademyofSciencesWuhan430072China LaboratoryofAnimalFatDepositionandMuscleDevelopment NorthwestSci-techUniversityofAgricultureandForestryYangling712100China InstituteofGeneticsandDevelopmentalBiology ChineseAcademyofSciencesBeijing100101China

149 complete mitochondrial DNA (mtDNA) cytochrome b (Cyt b) genes (1140 bp) of Gymnocypris przewalskii, Gymnocypris eckloni and Gymnocypris scolisto-mus from the Lake Qinghai, Yellow River and Qaidam Basin were sequenced and analyzed. Consistent dendrogram indi-cated that the samples collected from the same species do not constitute a separate monophyletic group and all the samples were grouped into three highly divergent lineages (A, B and C). Among them, Lineage A contained all samples of G. przewalskii from the Lake Qinghai and partial samples of the G. eckloni from the Yellow River. Lineage B contained the remaining samples of G. eckloni from the Yellow River. Lineage C was composed of a monophyletic group by G. eck-loni from the Qaidam Basin. Analysis of molecular variance (AMOVA) indicated that most of genetic variations were detected within these three mtDNA lineages (93.12%), sug-gesting that there are three different lineages of Gymnocypris in this region. Our Cyt b sequence data showed that G. przewalskii was not a polytypic species, and G. scolistomus was neither an independent species nor a subspecies of G. eckloni. The divergent mtDNA lineages of G. eckloni from the Yellow River suggested that gene flow between the different populations was restricted to a certain extent by several gorges on the upper reach of the Yellow River. Lineage B of G. eckloni might be the genetic effect from the ancestor which was incorporated with the endemic schizothoracine fishes when the headward erosion of the Yellow River reached to its current headwaters of late. The G. eckloni from Basin Qaidam was a monophyletic group (lineage C) and Fst values within G. eckloni from the Yellow River were higher than 0.98, suggesting that the gene flow has been interrupted for a long time and the G. eckloni from Basin Qaidam might have been evolved into different species by ecology segrega-tion. The correlation between the rakers number of Gymno-cypris and population genetic variation

关键词：分子学系统发生学细胞色素 DNA

Paleoenvironment evolution of the East Philippine Sea recorded in the new-type ferromanganese crust since the terminal Late Miocene

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2007年第8期50卷 1179-1188页

作者： XU zhaokai LI AnChun JIANG FuQing LI TieGang MENG QingYong JIN Ning Key Laboratory of Marine Geology and Environment Institute of OceanologyChinese Academy of SciencesQingdao 266071China Graduate University of Chinese Academy of Sciences Beijing 100039China

From systemic research of microstructure, geochemistry, uranium-series and 10Be isotope dating on a new-type deepwater ferromanganese crust from the East Philippine Sea, the paleoenvironment evolu-tion of the target area since the terminal Late Miocene was recovered. The vertical section changes of microstructure and chemical composition are consistent in the studied crust, which indicate three major accretion periods and corresponding paleoenvironment evolution of the crust. The bottom crust zone was formed in the terminal Late Miocene (5.6 Ma) with loose microstructure, high detritus content and high growth rate. Reductions of mineral element content, accretion rate and positive Ce-anomaly degree at 4.6 Ma indicate temporal warming, which went against the crust accretion and finally formed an accretion gap in the terminal Middle Pliocene (2.8―2.7 Ma). The more active Antarctic bottom sea-waters in the Late Pliocene (2.7 Ma) facilitated the fast transfer to the top pure crust zone. Hereafter, with the further apart of volcanic source and the keeping increase of eolian material (1.0 Ma), although surrounding conditions were still favorable, mineral element content still shows an obvious reducing trend. It thereby offers new carrier and data for the unclear paleoceanographic research of the target area since the terminal Late Miocene.

关键词： new-type ferromanganese crust record paleoenvironment evolution uranium-series dating 10Be isotope dating East Philippine Sea

Geochemical character and material source of sediments in the eastern Philippine Sea

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2008年第6期53卷 923-931页

作者： XU zhaokai LI AnChun JlANG FuQing XU FangJian Key Laboratory of Marine Geology and Environment Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China Department of Oceanography Kunsan National University Kunsan 573701 Republic of Korea Yantai Institute of Coastal Zone Research for Sustainable Development Chinese Academy of Sciences Yantai 264003 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

Based upon analyses of grain-size, rare earth element (REE) compositions, elemental occurrence phases of REE, and U-series isotopic dating, the sediment characteristics and material sources of the study area were examined for the recently formed deep-sea clays in the eastern Philippine Sea. The analytical results are summarized as follows. (1) Low accumulation rate, poor sorting and roundness, and high contents of grains coarser than fine silt indicate relatively low sediment input, with localized material source without long distance transport. (2) The REE Contents are relatively high. Shale-normalized patterns of REE indicate weak enrichment in heavy REE (HREE), Ce-passive anomaly, and Eu-positive anomaly. (3) Elemental occurrence phases of REE between the sediments with and without crust are similar. REE mainly concentrate in residual phase and then in ferromanganese oxide phase. The light REE (LREE) enrichment, Ce-positive anomaly, and Eu-positive anomaly occur in re- sidual phase. Ferromanganese oxide phase shows the characteristics of relatively high HREE content and Ce-passive anomaly. (4) There are differences in each above mentioned aspect between the sedi- ments with and without ferromanganese crust. (5) Synthesizing the above characteristics and source discriminant analysis, the study sediments are deduced to mainly result from the alteration of local and nearby volcanic materials. Continental materials transported by wind and/or river (ocean) flows also have minor contributions.

关键词：菲律宾海沉淀物稀土元素判别函数

A Detailed Review on License Plate Detection and Recognition Methods

在线全文

学校读者我要写书评

暂无评论

Journal of Traffic and Transportation Engineering(English Edition) 2024年

作者： zhaokai Li Muhammad Arslan Ghaffar School of Automobile， chang'an University

License Plate Detection and Recognition (LPDR) is crucial for Intelligent Transportation Systems (ITS) to ensure traffic safety and control. LPDR systems are widely used in traffic monitoring， vehicle safety， Vehicle-to-Vehicle (V2V) communication， and reducing traffic accidents. Modern technologies like autonomous driving and traffic optimization require secured V2V communication. Vehicles can use the LPDR system to identify nearby vehicles to communicate safely. With the expansion of applications in daily life， LPDR is facing many challenges. From the simple static camera used at the parking lot entrance， the LPDR systems are currently used for dynamic recognition of vehicle License Plates (LPs)， which is very difficult due to camera movement， camera angle， and distance from the vehicles. Recognizing LPs from different countries using a single algorithm is challenging since different nations use different characters， and LPs comprise multiple lines. For instance， Arabic characters could be more challenging to recognize. This article provides a performance comparison of several real-time tested and simulating LPDR methods. An ideal LPDR system must eliminate the challenges arising from new applications. The LPDR system needs to be designed to work accurately on static/dynamic conditions to develop V2V communication. By categorizing existing well-known LPDR approaches into conventional and machine learning techniques， this review tried to clarify the importance of each type of method. This work aims to review LP detection， character segmentation， and character recognition algorithms and provide guidance on future trends in this area.

关键词：