期刊文献+
共找到29,768篇文章
< 1 2 250 >
每页显示 20 50 100
To Be A Good Recorder of Plateau Ecology
1
作者 Xu Yuyao Li Xiaosu(译) 《China's Tibet》 2025年第3期40-44,共5页
Walking into the Institute of Plateau Biology(IPB in short)in Lhasa,Xizang,vice director Yang Le exchanged pleasantries with the guard in fluent Tibetan.Originally from Hunan Province,he has worked and lived here in X... Walking into the Institute of Plateau Biology(IPB in short)in Lhasa,Xizang,vice director Yang Le exchanged pleasantries with the guard in fluent Tibetan.Originally from Hunan Province,he has worked and lived here in Xizang for over 20 years."Now I see Xizang as my home,"he said with a smile. 展开更多
关键词 plateau ecology fluent tibetan originally LHASA vice director TIBETAN home Institute plateau Biology institute plateau biology ipb
在线阅读 下载PDF
Building Noah's Ark for Plateau Plant Seeds
2
作者 Kang Caiqi 《China's Tibet》 2025年第5期41-45,共5页
With an average elevation of over 4,500 meters and spanning 2.5 million square km,the Qinghai-Xizang Plateau is the highest and largest plateau on Earth,earning it the title the"roof of the world".Un surpris... With an average elevation of over 4,500 meters and spanning 2.5 million square km,the Qinghai-Xizang Plateau is the highest and largest plateau on Earth,earning it the title the"roof of the world".Un surprisingly,the plateau is home to exceptional biodiversity,making it one of the most biologically rich geographical regions in the world. 展开更多
关键词 BIODIVERSITY roof world Qinghai Xizang plateau highest largest plateau geographical region exceptional biodiversity biological richness
在线阅读 下载PDF
Evolutionary divergence on the Qinghai-Xizang Plateau:How life-history traits shape the diversity of plateau zokor and pika populations
3
作者 Yunyang Wei Tao Zhang +8 位作者 Zifeng Li Qinyang Hua Liduo Yin Menglong Lei Shilei Zhao Shanshan Gu Xin Zhang Hao He Xuemei Lu 《Journal of Genetics and Genomics》 2025年第9期1096-1108,共13页
Understanding how species diverge and adapt is fundamental to unraveling biodiversity.While environmental impacts on species evolution are well-documented,the roles of intrinsic life-history traits remain underexplore... Understanding how species diverge and adapt is fundamental to unraveling biodiversity.While environmental impacts on species evolution are well-documented,the roles of intrinsic life-history traits remain underexplored.The Qinghai-Xizang Plateau,with its harsh conditions and unique biodiversity,offers a natural laboratory for such investigations.Here,we examine two sympatric small mammals—the solitary,low-dispersal plateau zokor(Eospalax baileyi)and the social,high-dispersal plateau pika(Ochotona curzoniae)—to elucidate how life-history traits shape population structures and adaptive strategies.Through whole-genome sequencing and cardiac-blood phenotype analyses,we reveal striking differences in their evolutionary trajectories.Despite enduring similar environmental pressures,plateau zokor populations exhibit pronounced genetic subdivisions,high inbreeding,and distinct local adaptations.In contrast,plateau pika populations display genetic panmixia,widespread diversity,and adaptive uniformity.Demographic inference highlights that plateau zokors experienced severe population bottlenecks and restricted gene flow during glacial periods,underscoring the impact of dispersal capacity on evolutionary outcomes.Our findings demonstrate that intrinsic biological traits,particularly dispersal ability,fundamentally influence genetic architecture,population connectivity,and local adaptation.This study not only provides empirical evidence of how life-history traits shape evolutionary dynamics but also offers a framework for integrating intrinsic and extrinsic factors in understanding biodiversity formation. 展开更多
关键词 Life-history traits Population structure High-altitude adaptation Genetic diversity plateau zokor plateau pika
原文传递
Recent Vegetation Shifts on the Tibetan Plateau Exceed the Range of Variations Seen over Past Millennia in Pollen Record
4
作者 Kai Yi Xianyong Cao 《Journal of Earth Science》 2025年第3期1348-1350,共3页
The Tibetan Plateau(TP),known as the“Third Pole of Earth”,and its ecosystem is quite sensitive to climate change(Yao et al.,2012;Qiu,2008).In recent decades,the main TP has experienced warming and humidification(alt... The Tibetan Plateau(TP),known as the“Third Pole of Earth”,and its ecosystem is quite sensitive to climate change(Yao et al.,2012;Qiu,2008).In recent decades,the main TP has experienced warming and humidification(although there has been a drying trend in the southern region),and researchers anticipate that this change will continue in the future(Jiang et al.,2023;Sun et al.,2020;Chen et al.,2015). 展开更多
关键词 ecosystem sensitivity warming humidification Tibetan plateau warming climate change yao vegetation shifts climate change tibetan plateau tp known
原文传递
Spatiotemporal characteristics and influencing factors of vegetation water use efficiency on the Tibetan Plateau in 2001-2020 被引量:2
5
作者 HE Chenyang WANG Yanjiao +1 位作者 YAN Feng LU Qi 《Journal of Geographical Sciences》 2025年第1期39-64,共26页
Water use efficiency(WUE),as a pivotal indicator of the coupling degree within the carbon–water cycle of ecosystems,holds considerable importance in assessment of the carbon–water balance within terrestrial ecosyste... Water use efficiency(WUE),as a pivotal indicator of the coupling degree within the carbon–water cycle of ecosystems,holds considerable importance in assessment of the carbon–water balance within terrestrial ecosystems.However,in the context of global warming,WUE evolution and its primary drivers on the Tibetan Plateau remain unclear.This study employed the ensemble empirical mode decomposition method and the random forest algorithm to decipher the nonlinear trends and drivers of WUE on the Tibetan Plateau in 2001–2020.Results indicated an annual mean WUE of 0.8088 gC/mm·m^(2)across the plateau,with a spatial gradient reflecting decrease from the southeast toward the northwest.Areas manifesting monotonous trends of increase or decrease in WUE accounted for 23.64%and 9.69%of the total,respectively.Remarkably,66.67%of the region exhibited trend reversals,i.e.,39.94%of the area of the Tibetan Plateau showed transition from a trend of increase to a trend of decrease,and 26.73%of the area demonstrated a shift from a trend of decrease to a trend of increase.Environmental factors accounted for 70.79%of the variability in WUE.The leaf area index and temperature served as the major driving forces of WUE variation. 展开更多
关键词 water use efficiency spatiotemporal characteristic influencing factor Tibetan plateau
原文传递
Research progress on environmental behavior of arsenic in Qinghai-Tibet Plateau soil 被引量:1
6
作者 Xitong Li Chuangchuang Zhang +5 位作者 Aofan Wang Tieliang Zhang Zeying He Yujie Zhao Wenjing Liu Qiwen Zhou 《Journal of Environmental Sciences》 2025年第7期237-250,共14页
The Qinghai-Tibet Plateau,with its high altitude and cold climate,is one of the most fragile ecological environments in China and is distinguished by its naturally elevated arsenic(As)levels in the soil,largely due to... The Qinghai-Tibet Plateau,with its high altitude and cold climate,is one of the most fragile ecological environments in China and is distinguished by its naturally elevated arsenic(As)levels in the soil,largely due to its rich mineral and geothermal resources.This review provides a comprehensive analysis of As content,focusing on its distribution,environmental migration,and transformation behavior across the plateau.The review further evaluates the distribution of As in different functional areas,revealing that geothermal fields(107.2 mg/kg),mining areas(53.8 mg/kg),and croplands(39.3 mg/kg)have the highest As concentrations,followed by river and lake sediments and adjacent areas(33.1 mg/kg).These elevated levels are primarily attributed to the presence of As-rich minerals,such as arsenopyrite and pyrite.Additionally,human activities,including mining and geothermal energy production,exacerbate the release of As into the environment.The review also highlights the role of localmicroorganisms,particularly those fromthe phyla Proteobacteria and Actinobacteria,which possess As metabolic genes that facilitate As translocation.Given the unique climatic conditions of the plateau,conventionalmethods for As controlmay not be fully effective.However,the review identifies promising remediation strategies that are environmentally adaptable,such as the use of local microorganisms,specific adsorbents,and integrated technologies,which offer potential solutions for managing and utilizing Ascontaminated soils on the plateau. 展开更多
关键词 Qinghai-Tibet plateau SOIL ARSENIC Migration and transformation Ecological environment
原文传递
Construction of hard carbon with abundant closed ultra-micropores via a pre-oxidation strategy for high-efficiency sodium storage in the low potential plateau 被引量:1
7
作者 Wenbo Hou Lili Ma +6 位作者 Zhiyuan Liu Yiming Hu Wenxing Miao Bo Tao Kanjun Sun Hui Peng Guofu Ma 《Journal of Energy Chemistry》 2025年第6期65-75,I0003,共12页
Rationally regulating the porosity of hard carbon(HC),especially the closed pores matching the low potential plateau and the ultra-microporous structure suitable for Na+embedding,has been shown to be the key to improv... Rationally regulating the porosity of hard carbon(HC),especially the closed pores matching the low potential plateau and the ultra-microporous structure suitable for Na+embedding,has been shown to be the key to improving the sodium storage performance and initial coulombic efficiency(ICE).However,the preparation of such HC materials with specific pore structures still faces great challenges.Herein,a simple pre-oxidation strategy is employed to construct abundant closed ultra-microporous structures in soy protein powder-derived HC material,achieving a significant improvement in its ICE and platform capacity.The pre-oxidation process promotes the cross-linking degree of the soy protein,thereby hindering the directional growth of graphite domains during the carbonization process.The optimized HC exhibits ultra-high platform capacity(329 mAh g^(-1))and considerable energy density(148.5 Wh kg^(-1)).Based on the ex-situ Raman and X-ray photoelectron spectroscopy characterization results,the excellent sodium storage capacity of the HC material is attributed to the synergistic effect of adsorption-intercalation/filling.The presented work provides novel insights into the synthesis of other biomass-derived HC materials with abundant closed ultra-micro pores. 展开更多
关键词 Pre-oxidation strategy Closed ultra-micropores Low potential plateau Sodium-ion storage
在线阅读 下载PDF
Plateau frequency exploration of longitudinal guided waves for stress monitoring of steel strand 被引量:1
8
作者 ZHANG Jing LI Xuejian +2 位作者 LI Gang YUAN Ye YANG Dong 《Journal of Southeast University(English Edition)》 2025年第1期44-50,共7页
To tackle the issue of notch frequency and center frequency drift of the L(0,1)mode guided wave in ultra⁃sonic guided wave⁃based stress monitoring of prestressed steel strands,a method using higher⁃order mode plateau ... To tackle the issue of notch frequency and center frequency drift of the L(0,1)mode guided wave in ultra⁃sonic guided wave⁃based stress monitoring of prestressed steel strands,a method using higher⁃order mode plateau fre⁃quencies is adopted.First,the correlation between group velocity peaks and phase velocities at these plateau frequen⁃cies is analyzed.This analysis establishes a quantitative rela⁃tionship between phase velocity and stress in the steel strand,providing a theoretical foundation for stress monitor⁃ing.Then the two⁃dimensional Fourier transform is em⁃ployed to separate wave modes.Dynamic programming techniques are applied in the frequency⁃velocity domain to extract higher⁃order modes.By identifying the group veloc⁃ity peaks of these separated higher⁃order modes,the plateau frequencies of guided waves are determined,enabling indi⁃rect measurement of stress in the steel strand.To validate this method,finite element simulations are conducted under three scenarios.Results show that the higher⁃order modes of transient signals from three different positions can be ac⁃curately extracted,leading to successful cable stress moni⁃toring.This approach effectively circumvents the issue of guided wave frequency drift and improves stress monitoring accuracy.Consequently,it significantly improves the appli⁃cation of ultrasonic guided wave technology in structural health monitoring. 展开更多
关键词 steel strand ultrasonic guided wave plateau frequency mode separation stress monitoring
在线阅读 下载PDF
Massive Outbreak of Red Sprites in South Asia Observed from the Tibetan Plateau 被引量:1
9
作者 Hailiang HUANG Gaopeng LU +5 位作者 Angel AN Di XU Zhengwei CHENG Yongping WANG Yazhou CHEN Xin HUANG 《Advances in Atmospheric Sciences》 2025年第6期1247-1260,共14页
On 19 May 2022, an outbreak of 105 red sprites that occurred over South Asia was fortuitously recorded by two amateurs from a site in the southern Tibetan Plateau(TP), marking the highest number captured over a single... On 19 May 2022, an outbreak of 105 red sprites that occurred over South Asia was fortuitously recorded by two amateurs from a site in the southern Tibetan Plateau(TP), marking the highest number captured over a single thunderstorm in South Asia. Nearly half of these events involved dancing sprites, with an additional 16 uncommon secondary jets and at least four extremely rare green emissions called “ghosts” observed following the associated sprites. Due to the absence of the precise timing needed to identify parent lightning, a method based on satellite motion trajectories and star fields is proposed to infer video frame timestamps within an error of less than one second. After verifying 95 sprites from two videos, our method identified the parent lightning for 66 sprites(~70%). The sprite-producing strokes, mainly of positive polarity with peak currents exceeding +50 k A, occurred in the stratiform region of a mesoscale convective complex(MCC)that spanned the Ganges Plain to the southern TP, with a cloud area over 200 000 km2 and a minimum cloud-top black body temperature near 180 K. This observation confirms that thunderstorms in South Asia, akin to mesoscale convective systems(MCSs) in the Great Plains of the United States or coastal thunderstorms in Europe, can produce numerous sprites,including complex species. Our analysis bears important implications for characterizing thunderstorms above the southern TP and examining their physical and chemical effects on the adjacent regions, as well as the nature of the coupling between the troposphere and middle-upper atmosphere in this region. 展开更多
关键词 red sprites Tibetan plateau South Asia parent lightning strokes satellite trajectory mesoscale convective complex
在线阅读 下载PDF
Projection of extreme climate change in the Asian arid region and the Tibetan Plateau in the early and middle 21st century based on NEX-GDDP-CMIP6 被引量:1
10
作者 Yankun Sun Rui Zhu Tao Wang 《Atmospheric and Oceanic Science Letters》 2025年第3期53-58,共6页
In the context of global warming,it is anticipated that both the intensity and the frequency of future global extreme high precipitation(EHP)and extreme high temperature(EHT)events will increase.To evaluate the future... In the context of global warming,it is anticipated that both the intensity and the frequency of future global extreme high precipitation(EHP)and extreme high temperature(EHT)events will increase.To evaluate the future extreme climate changes in the Asian arid region and Tibetan Plateau,this study applied the NASA Earth Exchange Global Daily Downscaled Projections(NEX-GDDP-CMIP6)to assess the changes in EHP(Rx5d and R95pTOT)and EHT(TX90p and TXx)under different emission scenarios in the 21st century.Findings suggest that both the frequency and the intensity of the extreme indices will increase,exhibiting accelerated growth under higher emission scenarios,particularly under the SSP5-8.5 emission scenario.It is suggested that the growth of EHT and EHP in the early subperiod of the 21st century(2026-2045)will be relatively moderate,with small differences between different emission scenarios.However,by the middle subperiod of the 21st century(2041-2060),the differences between different emission scenarios will become larger than the 2035s and the growth will become more intense.In western central Asia,TX90p,TXx,Rx5d,and R95pTOT increase by 9.7%-14.2%(13.3%-24.7%),1.3℃-1.7℃(1.6℃-2.7℃),6.5%-8.9%(8.2%-8.8%),and 18.1%-27.0%(25.6%-30.0%)by the early(middle)subperiod;in eastern central Asia,TX90p,TXx,Rx5d,and R95pTOT increase 8.1%-12.0%(11.3%-21.1%),1.4℃-1.8℃(1.9℃-2.9℃),7.4%-9.7%(10.4%-13.8%),and 20.2%-29.3%(32.0%-40.8%)by the early(middle)subperiod;and over the Tibetan Plateau,TX90p,TXx,Rx5d,and R95pTOT increase 12.5%-17.4%(17.0%-31.0%),1.2℃-1.5℃(1.6℃-2.5℃),7.2%-10.0%(9.9%-15.0%),and 26.6%-33.1%(36.1%-55.3%)by the early(middle)subperiod. 展开更多
关键词 Extreme high precipitation Extreme high temperature Asian arid region Tibetan plateau NEX-GDDP-CMIP6
在线阅读 下载PDF
Check dams on China's Loess Plateau:An overview 被引量:1
11
作者 Zuyu Chen Shujing Chen +2 位作者 Penghai Yin Shu Yu Naichang Zhang 《River》 2025年第1期1-20,共20页
Check dams are widely constructed on China's Loess Plateau,which had a total number of 58,776 by the end of 2019.Great achievements in check dam construction have been gained regarding the economic and environment... Check dams are widely constructed on China's Loess Plateau,which had a total number of 58,776 by the end of 2019.Great achievements in check dam construction have been gained regarding the economic and environmental impacts.This study reviews the remarkable benefits of check dams on the land reclamation and environmental improvement on the Loess Plateau,and sediment reduction entering the Yellow River.However,the flood incidents on check dams have been frequently reported for the past decades,which has attracted more attention in the context of climate change and extreme rainfall events recently.Advances in the flood migration techniques achieved by the research group led by the first author have been highlighted to migrate the breach risk of check dams due to floods.The“family tree method”has been proposed to determine the survival status and critical rainfall threshold of each check dam in the complicated dam system.An updated dam breach flood evaluation framework and the corresponding numerical algorithm(i.e.,DB-IWHR)have been developed.Moreover,innovative types of water-release facilities for check dams,including geobag stepped spillway and prestressed concrete cylinder pipe in the underlying conduit,have been proposed and developed.Finally,the perspectives concerning the check dam construction on the Loess Plateau have been put forward. 展开更多
关键词 check dams China's Loess plateau DB-IWHR “family tree method” geobag stepped spillway
在线阅读 下载PDF
Mechanical properties and enhanced soil shear strength of herbaceous plant roots in the alpine meadow layer of the permafrost region on the Qinghai-Xizang Plateau,China 被引量:1
12
作者 HE Dequan LU Haijing +5 位作者 HU Xiasong WANG Cheng LIU Changyi ZHAO Yingxiao LI Shuaifei DENG Taiguo 《Journal of Arid Land》 2025年第4期515-537,共23页
The Qinghai-Xizang Plateau of China faces challenges like thaw slumping,threatening slope stability and infrastructure.Understanding the mechanical properties of the roots of the dominant herbaceous plant species in t... The Qinghai-Xizang Plateau of China faces challenges like thaw slumping,threatening slope stability and infrastructure.Understanding the mechanical properties of the roots of the dominant herbaceous plant species in the alpine meadow layer of the permafrost regions on the Qinghai-Xizang Plateau is essential for evaluating their role in enhancing soil shear strength and mitigating slope deformation in these fragile environments.In this study,the roots of four dominant herbaceous plant species—Kobresia pygmaea,Kobresia humilis,Carex moorcroftii,and Leontopodium pusillum—that are widely distributed in the permafrost regions of the Qinghai-Xizang Plateau were explored to determine their mechanical properties and effects in enhancing soil shear strength.Through indoor single root tensile and root group tensile tests,we determined the root diameter,tensile force,tensile strength,tensile ratio,and strength frequency distributions.We also evaluated their contributions to inhibiting slope deformation and failure during the formation and development of thermal thaw slumps in the alpine meadow.The results showed that the distribution of the root diameter of the dominant plant species is mostly normal,while the tensile strength tends to be logarithmically normally distributed.The relationship between the root diameter and root tensile strength conforms to a power function.The theoretical tensile strength of the root group was calculated using the Wu-Waldron Model(WWM)and the Fiber Bundle Model(FBM)under the assumption that the cumulative single tensile strength of the root bundle is identical to the tensile strength of the root group in the WWM.The FBM considers three fracture modes:FBM-D(the tensile force on each single root is proportional to its diameter relative to the total sum of all the root diameters),FBM-S(the cross-sectional stress in the root bundle is uniform),and FBM-N(each tensile strength test of individual roots experiences an equal load).It was found that the model-calculated tensile strength of the root group was 162.60%higher than the test value.The model-derived tensile force of the root group from the FBM-D,FBM-S,and FBM-N was 73.10%,28.91%,and 13.47%higher than the test values,respectively.The additional cohesion of the soil provided by the roots was calculated to be 25.90-45.06 kPa using the modified WWM,67.05-38.15 kPa using the FBM-S,and 57.24-32.74 kPa using the FBM-N.These results not only provide a theoretical basis for further quantitative evaluation of the mechanical effects of the root systems of herbaceous plant species in reinforcing the surface soil but also have practical significance for the effective prevention and control of thermal thaw slumping disasters in the permafrost regions containing native alpine meadows on the Qinghai-Xizang Plateau using flexible plant protection measures. 展开更多
关键词 thaw slumping soil shear strength root-soil composites root tensile force Wu-Waldron Model(WWM) Fiber Bundle Model(FBM) Qinghai-Xizang plateau
在线阅读 下载PDF
多输出Plateaued函数的密码学性质 被引量:5
13
作者 胡斌 金晨辉 史建红 《电子与信息学报》 EI CSCD 北大核心 2009年第6期1433-1437,共5页
该文对多输出Plateaued函数的一些密码学性质进行了研究,以多输出函数的特征函数为工具,建立了多输出Plateaued函数的差分转移概率与其Walsh谱及阶数之间的关系。给出了多输出Plateaued函数的Walsh谱值在一定条件下的分布情形,指出(n,m... 该文对多输出Plateaued函数的一些密码学性质进行了研究,以多输出函数的特征函数为工具,建立了多输出Plateaued函数的差分转移概率与其Walsh谱及阶数之间的关系。给出了多输出Plateaued函数的Walsh谱值在一定条件下的分布情形,指出(n,m,r)多输出Plateaued函数的在其输出分量函数的任意非零线性组合函数均为非平衡函数时,其输入变量个数n、输出变量个数m与其阶数r之间的关系满足m≤n?r/2。 展开更多
关键词 密码学 BENT函数 部分BENT函数 plateauED函数 多输出plateaued函数
在线阅读 下载PDF
Petrogenesis of the Xuexiumaer Biotite Quartz Monzonite Porphyry in Southern Gangdese and its Implications for Paleo-Crustal Thickness of the Qinghai-Tibet Plateau
14
作者 DAI Zuowen LI Guangming +3 位作者 LIU Hong HUANG Hanxiao FU Jiangang Jan Marten HUIZENGA 《Acta Geologica Sinica(English Edition)》 2025年第4期978-994,共17页
The Qinghai-Tibet Plateau possesses the thickest continental crust on Earth,yet the timing of its formation remains debated.In this study,we conducted zircon U-Pb isotopic dating,geochemical and Sr-Nd-Pb-Hf isotopic a... The Qinghai-Tibet Plateau possesses the thickest continental crust on Earth,yet the timing of its formation remains debated.In this study,we conducted zircon U-Pb isotopic dating,geochemical and Sr-Nd-Pb-Hf isotopic analyses on the Xuexiumaer biotite quartz monzonite porphyry(BQMP)sampled from the Lake Dajia area in southern Gangdese.This study aims to estimate the paleo-crustal thickness beneath this region during the early India-Asia collision stage using whole-rock Sr/Y and(La/Yb)N ratios as proxies.Results reveal that the Xuexiumaer BQMP was formed at~51 Ma in a collisional tectonic setting following Neo-Tethyan slab breakoff,and is an I-type granitoid derived primarily from partial melting of juvenile mafic lower crust with subordinate ancient crustal input.The estimated paleo-crustal thickness in the Lake Dajia area at~51 Ma is less than 40 km.This indicates that although the Qinghai-Tibet Plateau had already undergone significant crustal thickening and attained an exceptionally thick crust(>50 km)prior to the India-Asia collision as demonstrated by previous studies,some regions still maintained a crust only slightly thicker than the average continental crust(~35 km)at the initial collision stage.This limited crustal thickening likely resulted from underplating of subduction-related mafic magma at the mantle-crust boundary. 展开更多
关键词 paleo-crustal thickness PETROGENESIS Xuexiumaer GANGDESE Qinghai-Tibet plateau
在线阅读 下载PDF
Effects of plateau environment on cement concrete properties: A review
15
作者 Liangliang Li Liping Dang +4 位作者 Chengbing Wang Zhiyi Wei Dejun Han Zehua Chen Rui He 《Journal of Road Engineering》 2025年第3期467-479,共13页
The plateau environment not only affects the development of concrete's early strength but also damages its durability during its service life.This paper summarized and analyzed the impact of plateau environments o... The plateau environment not only affects the development of concrete's early strength but also damages its durability during its service life.This paper summarized and analyzed the impact of plateau environments on concrete’properties and proposed methods to improve the performance of concrete in plateau environment.The results indicated that low humidity and high evaporation rates in plateau regions inhibit the hydration of cement in concrete,leading to an increased content of micro-pores ranging from 500 to 1000 nm and raising the risk of early-stage cracking,thus reducing the impermeability of concrete.The low atmospheric pressure(AP)condition of 60 kPa decreases the entrained air content in concrete by over 20%,diminishes the pores under 200μm,and increases the average air-voids diameter and spacing factor,resulting in a decrease of more than 5%in the 28 d compressive strength of concrete.Consequently,the durability of concrete is compromised.Saponin and rosinbased air-entraining agents are recommended to improve the performance of concrete in plateau environments.Nanoparticles also aid in stabilizing bubbles in such conditions.Selecting low-heat specialty cements,increasing the amount of cement used,and extending the curing period are also vital measures to enhance the performance of plateau concrete. 展开更多
关键词 plateau environment CONCRETE Cement hydration Mechanical property Air-voids structure DURABILITY
在线阅读 下载PDF
Microplastic characteristics in rivers and lakes across the Tibetan Plateau
16
作者 YANG Ling KANG Shichang +4 位作者 ZHANG Yulan WANG Zhaoqing LUO Xi GUO Junming GAO Tanguang 《Journal of Mountain Science》 2025年第5期1571-1585,共15页
Microplastics have emerged as one of the most significant threats to the Earth's ecosystems due to their persistence,ability to carry high loads of contaminants,and biotoxicity.The Tibetan Plateau is a hotspot for... Microplastics have emerged as one of the most significant threats to the Earth's ecosystems due to their persistence,ability to carry high loads of contaminants,and biotoxicity.The Tibetan Plateau is a hotspot for global biodiversity conservation,but its ecosystem is fragile.This study systematically investigated the characteristics,distribution,sources,and ecological risk of microplastics in rivers and lakes across the Tibetan Plateau using the Laser Direct Infrared Imaging Spectroscopy(LDIR).The results indicated that the mean abundances of microplastics in water and sediments were 4250 items/m^(3)(n=50)and 3750 items/kg(n=44),respectively.Microplastics with small sizes(50-200μm),characterized by transparent and white fragments,were predominant.The most common polymers identified were polyamide(PA),polyurethane(PU),polyethylene terephthalate(PET),polyvinyl chloride(PVC),polypropylene(PP),and polyethylene(PE).Water sampling sites near urban/suburban effluent outfalls showed high levels of contamination.Microplastics in water are primarily derived from sewage effluent and atmospheric deposition.No single driver has been identified as the key factor influencing the spatial distribution of microplastics in water.The abundance of microplastics in sediments was significantly negatively correlated with the distance to the nearest city/town(p<0.01,R=-0.56)and significantly positively correlated with precipitation(p<0.01,R=0.60).Discarded or landfilled plastic waste is a major source of microplastics in sediments,which accumulate through transport by stormwater runoff caused by precipitation.Three ecological risk assessment models for microplastics were applied,and the high proportion of hazardous polymers such as PU,PVC,and PA was found to be responsible for the high ecological risk in the study area.This study provides an accurate and detailed exploration of the characteristics,sources,and spatial distribution of microplastic pollution by advanced automatic detection method in rivers and lakes on the Tibetan Plateau. 展开更多
关键词 Microplastics RIVERS LAKES LDIR Spectroscopy Environmental drivers Ecological risk Tibetan plateau
原文传递
Painting A VIVID TAPESTRY OF NEW LIFE ON SNOWY PLATEAU
17
作者 Liu Linlin CTIS(Translated) 《China's Tibet》 2025年第3期22-25,共4页
At first glance,Lhapa Tsering appears modestly dressed,A:almost unassumingyet an artistic air surrounds him.A man of few words,his eyes light up with unmistakable passion the moment painting enters the conversation.Hi... At first glance,Lhapa Tsering appears modestly dressed,A:almost unassumingyet an artistic air surrounds him.A man of few words,his eyes light up with unmistakable passion the moment painting enters the conversation.His fingers lightly graze the paintbrush. 展开更多
关键词 artistic air PAINTING PASSION snowy plateau
在线阅读 下载PDF
Untargeted metabolomics analysis of metabolite changes in gastric cancer patients from plateau regions
18
作者 Ling-Hong Zhu Zhao-Xin Jin +6 位作者 Yan-Qing Ma Xiao Feng Cai-Hong Ci Yun-Song Zhou Qiao-Ling Gu Yong-Mei Lan Zi-Long Zhang 《World Journal of Gastrointestinal Oncology》 2025年第9期74-88,共15页
BACKGROUND Metabolomics sequencing technology was used to investigate the changes of intestinal flora and metabolites in gastric cancer patients in plateau areas.AIM To investigate changes in gut microbiota and their ... BACKGROUND Metabolomics sequencing technology was used to investigate the changes of intestinal flora and metabolites in gastric cancer patients in plateau areas.AIM To investigate changes in gut microbiota and their metabolites in patients with gastric cancer from plateau regions using untargeted metabolomic sequencing.METHODS Fresh morning fecal samples were collected from 30 gastric cancer patients diagnosed at a tertiary hospital in Qinghai Province and 30 healthy individuals(controls).Liquid chromatography-tandem mass spectrometry based untargeted metabolomic sequencing was used to analyze metabolite changes and predict metabolic function.RESULTS Metabolomic analysis identified 281 metabolites in samples from both groups.These metabolites were categorized into eight major classes,listed in descending order of abundance:Lipids and lipid-like molecules(35.443%);organic acids and derivatives(29.114%);organic oxygen compounds(15.19%);nucleosides,nucleotides,and analogs(13.924%);organoheterocyclic compounds(2.532%),amino acids and peptides(1.266%);benzenoids(1.266%);and fatty acids(1.266%).Compared with the control group,the top 10 metabolites elevated in the gastric cancer group included:Dethiobiotin,glycylproline,glycine,hydroxyisocaproic acid,tyramine,methionine sulfoxide,5-aminopentanoic acid,citrulline,betonicine,and formiminoglutamic acid and the top 10 decreased were:Cytidine,5'-methylthioadenosine,trehalose,melibiose,lotaustralin,adenosine,inosine,ribothymidine,raffinose,and galactinol.Functional prediction analysis revealed that these differential metabolites were primarily enriched in 12 metabolic pathways,including purine metabolism,cysteine and methionine metabolism,galactose metabolism,lysine degradation,glycine,serine,and threonine metabolism,biotin metabolism,pyrimidine metabolism,arginine and proline metabolism,histidine metabolism,primary bile acid biosynthesis,starch and sucrose metabolism,and tyrosine metabolism.CONCLUSION Significant differences in intestinal microbial metabolites and associated metabolic pathways were observed between gastric cancer patients and healthy controls residing in plateau regions. 展开更多
关键词 plateau regions Gastric cancer Untargeted metabolomics METABOLITES Metabolic pathways
暂未订购
Spatial distribution of vegetation carbon stock among different organs over the Tibetan Plateau:on an intensive field survey
19
作者 Weixiang Cai Nianpeng He Li Xu 《Journal of Forestry Research》 2025年第1期311-320,共10页
Tibetan Plateau,as one of the most carbon intensive regions in China,is crucial in the carbon cycle,and accurately estimating its vegetation carbon density(C_(VEG))is essential for assessing regional and national carb... Tibetan Plateau,as one of the most carbon intensive regions in China,is crucial in the carbon cycle,and accurately estimating its vegetation carbon density(C_(VEG))is essential for assessing regional and national carbon balance.However,the spatial distribution of regional C_(VEG)is not available remains highly uncertain due to lack of systematic research,especially for different organs.Here,we investigated the spatial distribution patterns and driving factors of C_(VEG)among different plant organs(leaf,branch,trunk and root)by systematically field grid-sampling 2040 field-plots of plant communities over the Tibetan Plateau from 2019 to 2020.The results showed that the carbon content of plant organs ranged from 255.53 to 515.58 g kg^(-1),with the highest in branches and the lowest in roots.Among the different plant functional groups,the highest C_(VEG)was found in evergreen coniferous forests,and the lowest in desert grasslands,with an average C_(VEG)of 1603.98 g m^(-2).C_(VEG)increased spatially from northwest to southeast over the Tibetan Plateau,with MAP being the dominant factor.Furthermore,the total vegetation carbon stock on the Tibetan Plateau was estimated to be 1965.62 Tg for all vegetation types.Based on the comprehensive field survey dataset,the Random Forest model effectively predicted and mapped the spatial distribution of C_(VEG)(including aboveground,belowground,and the total biomass carbon density)over the Tibetan Plateau with notable accuracy(validation R2 values were 71%,56%,and 64%for C_(AGB),C_(BGB),and C_(VEG),respectively)at a spatial resolution of 1 km×1 km.Our findings can help improve the accuracy of regional carbon stock estimations and provide parameters for carbon cycle model optimization and remote sensing calibration in the future. 展开更多
关键词 Tibetan plateau VEGETATION Carbon density Carbon stock Machine learning
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部