检索结果-南通市图书馆

1970−2021年阿尔金山国家级自然保护区湖泊面积变化研究

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

北京师范大学学报（自然科学版） 2024年第4期60卷 541-550页

作者：杨岩岩张国明洪畅严平哈斯董苗王一娇周彦广中国林业科学研究院生态保护与修复研究所北京北京师范大学国家安全与应急管理学院北京北京师范大学环境演变与自然灾害教育部重点实验室北京北京师范大学地表过程与资源生态国家重点实验室北京北京师范大学应急管理部/教育部减灾与应急管理研究院北京北京师范大学地理科学学部北京

以阿尔金山国家级自然保护区内湖泊为研究对象,通过对大比例尺地形图和中高分辨率遥感影像的配准和目视解译,并结合保护区周边4个气象站1970−2021年气温、降水、蒸散量数据,系统分析了区内面积>1 km2湖泊的面积变化及其对气候因子的响应... 详细信息

以阿尔金山国家级自然保护区内湖泊为研究对象,通过对大比例尺地形图和中高分辨率遥感影像的配准和目视解译,并结合保护区周边4个气象站1970−2021年气温、降水、蒸散量数据,系统分析了区内面积>1 km2湖泊的面积变化及其对气候因子的响应.结果表明:1)近51 a保护区的湖泊呈现扩张、稳定和萎缩3种变化趋势,但大部分湖泊处于扩张状态.其中:大型湖泊均呈扩张之势,并以20世纪90年代中期为节点,前期扩展缓慢,后期出现明显扩展增速;中型湖泊面积变化呈现扩张、稳定和萎缩3种趋势;小型湖泊面积变化呈现扩张和萎缩2种趋势;湖泊面积的变化趋势与湖泊自身的规模无关,只与其补给和支出平衡有关.2)沙子湖、小沙子湖是部分河段被沙埋的流经湖,多年湖面积变化较小,湖泊周围沙丘未出现大范围朝湖向移动.3)保护区湖泊的面积与气温和降水呈正相关,与蒸发量呈显著负相关,气温和降水对湖泊面积的影响大于蒸发.保护区内湖泊属降雨和冰川融水补给型湖泊,且冰川融水的补给量大于降水.研究结果有助于了解该地区气候变化控制下水资源演变过程,可作为进一步评估区域气候变化和湖泊变化的依据.

关键词：阿尔金山国家级自然保护区湖泊面积变化特征影响因素

Strong phonon localization in PbTe with dislocations and large deviation to Matthiessen’s rule

在线全文

学校读者我要写书评

暂无评论

npj Computational Materials 2019年第1期5卷 277-282页

作者： Yandong Sun yanguang zhou Jian Han Wei Liu Cewen Nan Yuanhua Lin Ming Hu Ben Xu Laboratory of Advanced Materials School of Materials Science and EngineeringTsinghua UniversityBeijing 100084People’s Republic of China Mechanical and Aerospace Engineering Department University of California Los AngelesLos AngelesCA 90095USA State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084People’s Republic of China Department of Mechanical Engineering University of South CarolinaColumbiaSC 29208USA

Dislocations can greatly enhance the figure of merit of thermoelectric materials by prominently reducing thermal ***,the evolution of phonon modes with different energies when they propagate through a single dislocation is *** we perform non-equilibrium molecular dynamics simulation to study phonon transport in PbTe crystal with dislocations by excluding boundary scattering and strain coupling *** frequency-dependent heat flux,phonon mode analysis,and frequency-dependent phonon mean free paths(MFPs)are *** thermal conductivity of PbTe with dislocation density on the order of 10^(15)m^(−2) is decreased by 62%.We provide solid evidence of strong localization of phonon modes in dislocation ***,by comparing the frequency-dependent phonon MFPs between atomistic modeling and traditional theory,it is found that the conventional theories are inadequate to describe the phonon behavior throughout the full phonon spectrum,and large deviation to the well-known semi-classical Matthiessen’s rule is *** results provide insightful guidance for the development of PbTe based thermoelectrics and shed light on new routes for enhancing the performance of existing thermoelectrics by incorporating dislocations.

关键词： phonon dislocation deviation

Highly Thermo-Conductive Three-Dimensional Graphene Aqueous Medium

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

Nano-Micro Letters 2020年第10期12卷 224-235页

作者： Zheng Bo Chongyan Ying Huachao Yang Shenghao Wu Jinyuan Yang Jing Kong Shiling Yang yanguang zhou Jianhua Yan Kefa Cen State Key Laboratory of Clean Energy Utilization Institute for Thermal Power EngineeringCollege of Energy EngineeringZhejiang University38 Zheda RoadHangzhou 310027People’s Republic of China ZJU-Hangzhou Global Scientific and Technological Innovation Center Hangzhou 311215People’s Republic of China Department of Mechanical and Aerospace Engineering The Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongPeople’s Republic of China

Highly thermo-conductive aqueous medium is a crucial premise to demonstrate high-performance thermal-related *** has the diamond comparable thermal conductivity,while the intrinsic two-dimensional reality will result in strong anisotropic thermal conductivity and wrinkles or even crumples that significantly sacrifices its inherent properties in practical *** strategy to overcome this is to use three-dimensional(3D)architecture of ***,3D graphene structure with covalent-bonding nanofins(3D-GS-CBF)is proposed,which is then used as the filler to demonstrate effective aqueous *** thermal conductivity and thermal conductivity enhancement efficiency of 3D-GS-CBF(0.26 vol%)aqueous medium can be as high as 2.61 W m-1 K-1 and 1300%,respectively,around six times larger than highest value of the existed aqueous ***,3D-GS-CBF can be stable in the solution even after 6 months,addressing the instability issues of conventional graphene networks.A multiscale modeling including non-equilibrium molecular dynamics simulations and heat conduction model is applied to interpret experimental results.3D-GS-CBF aqueous medium can largely improve the solar vapor evaporation rate(by 1.5 times)that are even comparable to the interfacial heating system;meanwhile,its cooling performance is also superior to commercial coolant in thermal management applications.

关键词： Three-dimensional graphene Thermo-conductive aqueous medium Multiscale modeling Solar thermal conversion Practical thermal management

Activation of the wnt/β-catenin/CYP1B1 pathway alleviates oxidative stress and protects the blood-brain barrier under cerebral ischemia/reperfusion conditions

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2024年第7期19卷 1541-1547页

作者： Xingyong Chen Nannan Yao yanguang Mao Dongyun Xiao Yiyi Huang Xu Zhang Yinzhou Wang Department of Neurology Fujian Provincial HospitalShengli Clinical Medical College of Fujian Medical UniversityFuzhouFujian ProvinceChina Department of Neurology Cangzhou Central HospitalCangzhouHebei ProvinceChina Fujian Academy of Medical Science FuzhouFujian ProvinceChina Key Testing Laboratory of Fujian Province FuzhouFujian ProvinceChina

Accumulating evidence suggests that oxidative stress and the Wnt/β-catenin pathway participate in stroke-induced disruption of the blood-brain ***,the potential links between them following ischemic stroke remain largely *** present study found that cerebral ischemia leads to oxidative stress and repression of the Wnt/β-catenin ***,Wnt/β-catenin pathway activation by the pharmacological inhibito r,TWS119,relieved oxidative stress,increased the levels of cytochrome P4501B1(CYP1B1)and tight junction-associated proteins(zonula occludens-1[ZO-1],occludin and claudin-5),as well as brain microvascular density in cerebral ischemia *** r,rat brain microvascular endothelial cells that underwent oxygen glucose deprivation/reoxygenation displayed intense oxidative stress,suppression of the Wnt/β-catenin pathway,aggravated cell apoptosis,downregulated CYP1B1and tight junction protein levels,and inhibited cell prolife ration and *** ofβ-catenin or knockdown ofβ-catenin and CYP1B1 genes in rat brain mic rovascular endothelial cells at least partly ameliorated or exacerbated these effects,*** addition,small interfering RNA-mediatedβ-catenin silencing decreased CYP1B1 expression,whereas CYP1B1 knoc kdown did not change the levels of glycogen synthase kinase 3β,Wnt-3a,andβ-catenin proteins in rat brain microvascular endothelial cells after oxygen glucose deprivatio n/***,the data suggest that CYP1B1 can be regulated by Wnt/β-catenin signaling,and activation of the Wnt/β-catenin/CYP1B1 pathway contributes to alleviation of oxidative stress,increased tight junction levels,and protection of the blood-brain barrier against ischemia/hypoxia-induced injury.

关键词： blood-brain barrier CYP1B1 oxidative stress oxygen glucose deprivation/reoxygenation tight junction vascular endothelial cells Wnt/β-catenin pathway β-catenin

A New Discovery of Mineralization as Subseafloor Hydrothermal Replacement in the Duddar Super-Large SEDEX Lead-Zinc Deposit in Pakistan

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2024年第3期35卷 1075-1078页

作者： Huishan Zhang Yucai Song Jianing Sun Jun Hong Yasir Shaheen Khalil yanguang Li Haidi Zhang Zhihua Wang MNR Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits Xi’an Center of Geological SurveyChina Geological SurveyXi’an 710054China Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China Chengdu Center of Geological Survey China Geological SurveyChengdu 610081China China Huaye Group Co. LtdBeijing 100037China Geological Survey of Pakistan Islamabad 44000Pakistan

0 INTRODUCTION Sedimentary exhalative(SEDEX)lead-zinc deposit was traditionally considered as a result of submarine hydrothermal exhalation,including exhalative plume and brine pool models(Izanloo et al.,2022;Spinks et al.,2021;Maghfouri et al.,2020;Sangster,2020,2018;Huang et al.,2019;Rajabi et al.,2015;Goodfellow and Lydon,2007;Large et al.,2005,2001;Peng et al.,2000;Goodfellow et al.,1993;Figures 1a,1b).However,recognition of mineralization as subseafloor hydrothermal replacement in a few SEDEX deposits has challenged the traditional consideration(Magnall et al.,2023,2021,2020a,b;Hayward et al.,2021;Figure 1c).Researchers come to believe that subseafloor replacement rather than submarine exhalation is a dominant process for SEDEX mineralization,but this needs to be examined through more case studies.

关键词： submarine mineralization seafloor

Distribution, burial fluxes and carbon sink effect of sedimentary organic carbon in the eastern China seas

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2024年第10期67卷 3062-3082页

作者： Xuefa SHI Bin WU Shuqing QIAO Zhengquan YAO Limin HU Yazhi BAI Shan HU Jie SHENG yanguang LIU Shengfa LIU Kunshan WANG Jianjun ZOU Key Laboratory of Marine Geology and Metallogeny First Institute of OceanographyMinistry of Natural ResourcesQingdao 266061China Laboratory for Marine Geology Qingdao Marine Science and Technology CenterQingdao 266237China Key Laboratory of Deep Sea Mineral Resources Development Shandong Province(Preparatory)Qingdao 266061China Key Laboratory of Submarine Geosciences and Technology College of Marine GeosciencesOcean University of ChinaQingdao 266100China

The ocean is the largest active carbon reservoir on Earth. Organic carbon(OC), as the primary species of carbon sequestration in the ocean, plays an important role in the global carbon cycle through its deposition and burial. In this study,sedimentary OC data from 5796 stations, together with relevant geochemical and sedimentological parameters in the Bohai Sea,Yellow Sea, and East China Sea(BYES) were used to summarize and elucidate the distribution and burial patterns of sedimentary OC, and assess carbon sink effect of sedimentary OC burial. The results show that the OC content in the sediments of the BYES ranges from 0.00% to 2.12%, with an average content of 0.47%±0.26%. OC content is significantly correlated with finegrained sediments, with an average OC content in mud areas being 39% higher than that in non-mud areas. Modern OC buried in the BYES are mainly deposited in 7 major mud areas, with a total sedimentary OC burial flux of approximately 8.20 Mt C yr^(–1).Among them, the burial flux of biospheric OC is 6.92 Mt C yr^(–1), equivalent to the OC consumption amount of silicate weathering of the 9 major river basins in the eastern China. In its natural state, the annually sequestered OC in the sediments of the eastern China seas is equivalent to 25.37 Mt of atmospheric CO_(2), indicating a significant carbon sink effect. The distribution and burial of terrigenous OC in the BYES are mainly influenced by the large river inputs and complex marine hydrodynamic environment,while human activities such as dam construction have significantly altered the OC burial in these coastal mud areas.

关键词： Sedimentary organic carbon Burial flux Carbon sink effect Carbon cycle Eastern China seas

在线全文

学校读者我要写书评

暂无评论

利用验潮站资料的中国近岸海潮模型精度评估

测绘科学 2017年第8期42卷 28-32页

作者：付延光周兴华周东旭孙维康宋艳朋山东科技大学测绘科学与工程学院山东青岛266590 国家海洋局第一海洋研究所山东青岛266061

针对全球海潮模型在我国近海海域精度较差的问题,该文采用中国沿岸30个长期验潮站的调和常数,对比了3种全球海潮模型DTU10、TPXO7.2、NAO.99b和1个区域海潮模型NAO.99Jb在中国沿岸的准确度。通过海潮模型与验潮站分潮的振幅中误差、迟... 详细信息

针对全球海潮模型在我国近海海域精度较差的问题,该文采用中国沿岸30个长期验潮站的调和常数,对比了3种全球海潮模型DTU10、TPXO7.2、NAO.99b和1个区域海潮模型NAO.99Jb在中国沿岸的准确度。通过海潮模型与验潮站分潮的振幅中误差、迟角中误差以及8个主要分潮的预报误差,对渤海、黄海、东海和南海北部进行了详细的分析。结果表明,NAO.99Jb在中国海域精度最高,NAO.99b次之。在渤海海域,DTU10在Q_1分潮精度最高,NAO.99b在K2分潮精度最高,其余分潮均是NAO.99Jb精度最高;在黄海海域,NAO.99b在Q_1分潮精度最高,其余分潮均是NAO.99Jb精度最高;在东海海域,DTU10在Q_1分潮精度最高,TPXO7.2在P1精度最高,NAO.99Jb在O1、M2分潮精度最高,其余分潮均是NAO.99b精度最高;在南海北部海域,DTU10在N2、S2分潮精度最高,其余分潮均是NAO.99Jb精度最高。

关键词：海洋潮汐模型验潮站卫星测高调和分析

库布齐沙漠南缘沙丘固定与活化过程中的形态演变

在线全文

学校读者我要写书评

暂无评论

中国沙漠 2016年第5期36卷 1223-1229页

作者：刘丹管超周炎广陶彬彬哈斯额尔敦北京师范大学资源学院北京100875

以1998—2014年5期库布齐沙漠南缘的遥感影像为主要数据源,结合野外调查分析了沙丘固定与活化过程中的形态演变,探讨了区域风况和降水等气象要素对沙丘固定与活化及形态演变的影响。结果表明:研究区沙丘随降水量的年际波动经历了固定-活... 详细信息

以1998—2014年5期库布齐沙漠南缘的遥感影像为主要数据源,结合野外调查分析了沙丘固定与活化过程中的形态演变,探讨了区域风况和降水等气象要素对沙丘固定与活化及形态演变的影响。结果表明:研究区沙丘随降水量的年际波动经历了固定-活化-再固定3个阶段。监测初期的片状流动沙丘演变为大型抛物线形沙丘并得以固定,固定的抛物线形沙丘以发育风蚀坑形式活化,进而形成多个抛物线形沙丘,最后这些沙丘又被植被固定,沙丘形态趋于更加复杂。但在此过程中,风的作用并不显著。研究区抛物线形沙丘既可起源于新月形沙丘或片状流沙,也可由风蚀坑发育而成,其中植被作为沙丘的重要组成部分,起着重要作用。同时发现在抛物线形沙丘移动过程中,当背风坡发育滑落面时,沙丘的移动最快。

关键词：沙丘固定活化形态演变库布齐沙漠

在线全文

学校读者我要写书评

暂无评论

毛乌素沙地新垦地土壤风蚀特征

农业工程学报 2020年第1期36卷 138-147页

作者：周炎广武子丰胡日娜李红悦王卓然哈斯额尔敦北京师范大学地理科学学部自然资源学院

为了理解近期沙地农业开发的土壤风蚀风险及其对区域沙漠化的影响。该文对毛乌素沙地灌丛沙堆地、沙质草地以及耕地不同位置进行了多组风沙同步观测,并对所收集的沙物质进行粒度分析。结果表明:草地与灌丛地被开垦为耕地后,土壤风蚀强... 详细信息

为了理解近期沙地农业开发的土壤风蚀风险及其对区域沙漠化的影响。该文对毛乌素沙地灌丛沙堆地、沙质草地以及耕地不同位置进行了多组风沙同步观测,并对所收集的沙物质进行粒度分析。结果表明:草地与灌丛地被开垦为耕地后,土壤风蚀强度成倍数增长。在可蚀性颗粒充足的耕地,输沙率顺风向趋于增加的同时,随高度的增加,输沙率在0~10 cm高度内以指数函数规律递减,在10~20 cm高度内以幂函数规律递减;总输沙率与风速呈较好的幂函数关系,侵蚀模数约为9 657 t/(km^2·a)。该文认为,新垦地的出现对区域沙漠化具有重要影响,其面积应作为评价区域沙漠化的重要指标;减小裸露耕地面积,建立防风固沙林,保留一定高度的留茬,可有效控制新垦地的土壤风蚀问题。

关键词：风侵蚀粒度输沙率风沙流结构毛乌素沙地