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Seedling dynamics differ between canopy species and understory species in a tropical seasonal rainforest,SW China

Plant Diversity 2024年第5期46卷 671-677页

作者： Libing Pan Xiaoyang Song Wenfu zhang Jie Yang Min Cao CAS Key Laboratory of Tropical Forest Ecology Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesMenglunMengla 666303YunnanChina College of Life Sciences University of Chinese Academy of SciencesBeijing 100049China

We used 11 years of census data from 450 seedling quadrats established in a 20-ha forest dynamics plot to study seedling dynamics in tree species of a tropical seasonal rainforest in Xishuangbanna,southwestern *** found that overall seedling recruitment rate and relative growth rate were higher in the rainy season than in the dry *** the recruitment rate of seedlings from canopy tree species(two species)and the relative growth rate of seedlings from understory species(nine species)were higher in the rainy season than in the dry ***,in the rainy season,the recruitment rate of seedlings was higher for canopy tree species than for understory tree *** addition,relative growth rate of seedlings was higher in the canopy species than in understory seedlings in the dry *** also observed that,in both rainy and dry seasons,mortality rate of seedlings was higher for canopy species than for understory ***,canopy tree species appear to have evolved a flexible strategy to adapt to the seasonal changes of a monsoon *** contrast,understory tree species seem to have adopted a conservative ***,these species mainly release seedlings in the rainy season and maintain relatively stable populations with a lower mortality rate and recruitment rate in both dry and rainy *** study suggests that canopy and understory seedling populations growing in forest understory may respond to future climate change scenarios with distinct regeneration strategies.

关键词： Tropical forest Tree seedling Seasonality Recruitment Mortality Relative growth rate

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Building mm Wave on the Evolving C-V2X:mm Wave NR-V2X

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China Communications 2024年第1期21卷 88-101页

作者： Shanzhi Chen Xinxin He Rui Zhao Jinling Hu Xin zhang China Information and Communication Technology Group Co. Ltd.(CICT)the State Key Laboratory of Wireless Mobile CommunicationsBeijing 100083China Beijing Laboratory of Advanced Information Networks Beijing Key Laboratory of Network System Architecture and ConvergenceBeijing University of Posts and TelecommunicationsBeijing 100876China CICT Connected and Intelligent Technologies Co. LtdChina Academy of Telecommunication TechnologyBeijing 100191China CICT Mobile Communications Technology Co.Ltd.

Since the evolving standardization of cellular V2X(C-V2X)technologies is continuously developed by 3GPP,research on new radio(NR-V2X)has been on schedule by academic and *** millimeter wave(mm Wave)frequency band is supposed to provide large transmission bandwidth,yet the development of mm Wave band in NR-V2X is still in preliminary *** this article,a comprehensive discussion of mm Wave NR-V2X is given covering trends,standardization landscape,and enabling technologies,aiming at tackling the challenge of channel modeling,directional channel access,beamforming and blockage *** vision of mm Wave NR-V2X is to fully support the development of automated driving,holographic control display and improved in-car infotainment for the future.

关键词： C-V2X enabling technologies mmWave NR-V2X

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An improved strain-softening constitutive model of granite considering the effect of crack deformation

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第4期16卷 1202-1215页

作者： Yapeng Li Qiang zhang Qiuxin Gu Peinan Wu Binsong Jiang State Key Laboratory for Geomechanics and Deep Underground Engineering School of Mechanics and Civil EngineeringChina University of Mining and TechnologyXuzhou221116China

This paper presents an improved strain-softening constitutive model considering the effect of crack deformation based on the triaxial cyclic loading and unloading test *** improved model assumes that total strain is a combination of plastic,elastic,and crack *** constitutive relationship between the crack strain and the stress was further *** evolutions of mechanical parameters,*** parameters,dilation angle,unloading elastic modulus,and deformation parameters of crack,with the plastic strain and confining pressure were *** the increase in plastic strain,the cohesion,friction angle,dilation angle,and crack Poisson's ratio initially increase and subsequently decrease,and the unloading elastic modulus and the crack elastic modulus nonlinearly *** increasing confining pressure enhances the strength and unloading elastic modulus,and decreases the dilation angle and Poisson's ratio of the *** theoretical triaxial compressive stress-strain curves were compared with the experimental results,and they present a good agreement with each *** improved constitutive model can well reflect the nonlinear mechanical behavior of granite.

关键词： Strain-softening Crack deformation effect Plastic shear strain Constitutive model

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金属微粒影响三电极气体火花开关击穿过程的仿真研究

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物理学报 2024年第1期73卷 248-257页

作者：周鑫淼张博雅陈立李兴文西安交通大学电工材料电气绝缘全国重点实验室西安710049

气体火花开关在脉冲功率技术中得到了大量应用,但由于脉冲功率技术大电流高电压的特点,气体火花开关在使用过程中很容易对电极表面造成烧蚀,烧蚀产生的金属微粒会显著影响开关的稳定性和可靠性.本文首先针对大气压氮气环境下的三电极气... 详细信息

气体火花开关在脉冲功率技术中得到了大量应用,但由于脉冲功率技术大电流高电压的特点,气体火花开关在使用过程中很容易对电极表面造成烧蚀,烧蚀产生的金属微粒会显著影响开关的稳定性和可靠性.本文首先针对大气压氮气环境下的三电极气体火花开关放电过程进行建模,对触发极边缘高场强区域的电离系数进行修正,使用场致电子发射电流模拟初始电子产生的过程,深入探究开关导通的物理机理,详细叙述开关击穿过程各阶段的放电形态.接着研究了金属微粒对于击穿过程的影响,研究表明金属微粒的存在增强了触发极附近的电场,加速了初始电子云的产生,同时金属微粒与触发极之间会率先击穿,并成为后续流注发展的源头.除此之外,金属微粒对于流注的传播具有阻碍作用,使放电通道产生分支.最后本文讨论了不同形状以及尺寸的金属微粒对于放电过程的影响,这些都为进一步研究三电极气体火花开关放电过程以及金属微粒诱发开关击穿的物理机理提供了理论支撑.

关键词：流注放电气体火花开关金属微粒场致发射

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Eutrophication of Jiangsu Coastal Water and Its Role in the Formation of Green Tide

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Journal of Ocean University of China 2024年第1期23卷 109-118页

作者： XIAO Mingyan SONG Weina zhang Haibo SHI Xiaoyong SU Rongguo Key Laboratory of Marine Chemistry Theory and Technology Ministry of EducationOcean University of ChinaQingdao 266100China National Marine Environmental Monitoring Center Dalian 116000China National Marine Hazard Mitigation Service Beijing 100194China

Since 2007,the large-scale green tide caused by Ulva prolifera(***)have occurred as a recurrent phenomenon in the southern Yellow Sea of *** surveys and satellite remote sensing showed that the small scattered patches of green tide algae were first observed along the Porphyra agriculture area of the Subei Shoal in late *** this study,we attempted to identify the role of eutrophication in the origin of the green tide in the Subei Shoal and its adjacent *** Shoal and its adjacent area are characterized by rich nutrients,especially NO_(3)^(-)-N,NH_(4)^(+)-N,PO_(4)^(3-)-P,and other bioavailable components(such as urea-N and amino acids).In the spring of 2017,the average concentrations of NO_(3)^(-)-N were 19.01±11.01μmolL^(-1),accounting for 86.68%of the dis-solved inorganic nitrogen(DIN).In addition,the average concentration of NH4^(+)-N was 2.51±1.60μmolL^(-1).PO_(4)^(3-)-P had an average concentration of 0.14±0.13μ*** average concentrations of urea-N and total hydrolyzed amino acids(THAA)were 1.73±1.36μmolL^(-1)and 1.33±0.80μmolL^(-1),*** nutritive substances play a key role in the rapid production of *** and make the Jiangsu coastal water an incubator for green tide.

关键词： green tide nutrients algae Ulva prolifera eutrophication Subei Shoal

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High-resolution reconstruction of April-September precipitation and major extreme droughts in China over the past∼530 years

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Science Bulletin 2024年第17期69卷 2756-2764页

作者： Yongxiang zhang Hongli Wang Xuemei Shao Hongbin Liu Haifeng Zhu Lily Wang Eryuan Liang Zhixin Hao Xiuqi Fang Qibin zhang Jinjian Li Xinghe Shi Yujiang yuan Feng Chen Tongwen zhang Ruibo zhang Huaming Shang Jianfeng Peng National Climate Centre China Meteorological AdministrationBeijing 100081China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Beijing New Epoch School the Administrative Bureau of Chinese Academy of SciencesBeijing 100086China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Alpine Ecology Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China CAS Center for Excellence in Tibetan Plateau Earth Sciences Beijing 100101China Faculty of Geographical Science Beijing Normal UniversityBeijing 100875China State Key Laboratory of Vegetation and Environmental Change Institute of BotanyChinese Academy of SciencesBeijing 100093China School of Atmospheric Sciences Plateau Atmosphere and Environment Key Laboratory of Sichuan ProvinceChengdu University of Information TechnologyChengdu 610225China Qinghai Climate Centre Xining 810001 China Key Laboratory of Tree-Ring Physical and Chemical Research of China Meteorological Administration Key Laboratory of Tree-Ring Ecology of Xinjiang Uygur Autonomous RegionInstitute of Desert MeteorologyChina Meteorological AdministrationUrumqi 830002China Yunnan Key Laboratory of International Rivers and Transboundary Eco-Security Institute of International Rivers and Eco-SecurityYunnan UniversityKunming 650000China College of Geography and Environmental Science Henan UniversityKaifeng 475004China

Extreme drought events have increased,causing serious losses and damage to the social economy under current warming ***,short-term meteorological data limit our understanding and projection of these *** the accumulation of proxy data,especially tree-ring data,large-scale precipitation field reconstruction has provided opportunities to explore underlying mechanisms *** point-by-point regression,we reconstructed the April-September precipitation field in China for the past~530 years on the basis of 590 proxy records,including 470 tree-ring width chronologies and 120 drought/flood *** regression models explained average 50%of the variance in *** the statistical test on calibration and verification,our models passed the significance level that assured reconstruction *** reconstruction data performed well,showing consistency and better quality than previously reported *** first three leading modes of variability in the reconstruction revealed the main distribution modes of precipitation over ***/drought and extremely wet/drought years accounted for 12.81%/10.92%(68 years/58 years)and 1.69%/3.20%(9 years/17 years)of the past~530 years in China,*** extreme drought events can be identified explicitly in our *** detailed features of the Chongzhen Great Drought(1637-1643),the Wanli Great Drought(1585-1590),and the Ding-Wu Great Famine(1874-1879),indicated the existence of potentially different underlying mechanisms that need further *** further improvements can be made for remote uninhabited areas and large deserts,our gridded reconstruction of April-September precipitation in China over the past~530 years can provide a solid database for studies on the attribution of climate change and the mechanism of extreme drought events.

关键词： Precipitation reconstruction Tree rings Historical documents Precipitation variability Extreme droughts

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Variations and future projections of glacial discharge of Urumqi River Headwaters,eastern Tien Shan(1980s-2017)

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Advances in Climate Change Research 2024年第3期15卷 537-546页

作者： Hui zhang Fei-Teng WANG Ping ZHOU Yi-Da XIE State Key Laboratory of Cryospheric Science Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Key Laboratory of Cryospheric Science and Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

To address data scarcity on long-term glacial discharge and inadequacies in simulating and predicting hydrological processes in the Tien Shan,this study analysed the observed discharge at multiple timescales over 1980se2017 and projected changes within a representative glacierized high-mountain region:eastern Tien Shan,Central *** processes were simulated to predict changes under four future scenarios(SSP1,SSP2,SSP3,and SSP5)using a classical hydrological model coupled with a glacier dynamics *** rates at annual,monthly(June,July,August)and daily timescales were obtained from two hydrological gauges:Urumqi Glacier No.1 hydrological station(UGH)and Zongkong station(ZK).Overall,annual and summer discharge increased significantly(pboth stations over the study *** intra-annual variations mainly resulted from differences in their recharge *** simulations show that a tipping point in annual discharge at UGH may occur between 2018 and 2024 under the four SSPs *** discharge is predicted to cease earlier at ZK than at *** relates to glacier type and size,suggesting basins with heavily developed small glaciers will reach peak discharge sooner,resulting in an earlier freshwater supply *** findings serve as a reference for research into glacial runoff in Central Asia and provide a decision-making basis for planning local water-resource projects.

关键词： Observed glacial discharge Temporal variations Urumqi River Headwaters Eastern Tien Shan Simulation and projection

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Global Research Progress on Municipal Waste and Future Prospect Based on the Cross-national Comparisons

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Chinese Geographical Science 2024年第2期34卷 250-264页

作者： zhang Yuxin LIU Xiaoqian YAN Xiaoxia MA Sike MAO Weiyun College of Applied Arts and Science of Beijing Union University Beijing 100191China

Due to the acceleration of urbanization,the municipal waste(MW)problem has transformed into a global challenge for urb-an *** elucidate historical trends,current focal points,and future directions in MW research,we conducted a bibliometric analysis and employed knowledge graph visualization to scrutinize a total of 34212 articles,which were published between 1991 and 2021 in the Web of Science(WoS)core *** results indicated that current major research themes encompass waste classifica-tion and recycling,waste management and public behavior,waste disposal methods and technologies,as well as environmental impact and *** has been a shift in the research focus from the environmental impacts of waste incineration to sustainable manage-ment related issues.A comparison of research from six typical countries revealed the differences in research priorities and techniques *** from the USA and Britain initiated MW research earlier than other countries and investigated management issues in depth,such as public behavior and willingness to ***,Japanese,German,and Swedish scholars conducted extensive studies on advanced waste treatment technologies,such as disposal and recycling,risk assessment,and waste-to-energy *** scholars placed particular emphasis on end-of-pipe treatments and their associated environmental *** and poten-tial future frontiers were identified by burst detection *** with high value of burst index(BI)worldwide are food waste and circular *** scholars have put great efforts on waste environmental impact and its recycling technologies,while we’re expecting to further investigating vulnerable ***,this study contributes to bridging the regional gap of scientific research among different countries and fostering international collaboration.

关键词： bibliometrics municipal waste(MW) CiteSpace hotspot prediction burst index(BI) sustainability cross-national comparison Web of Science(WoS)

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Open-vessel Synthesis of Poly-N-methoxyethylglycine

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Chemical Research in Chinese Universities 2024年第1期40卷 153-158页

作者： LIU Guojan MA Ke CHEN Qi zhang Donghui LIU Runhui State Key Laboratory of Bioreactor Engineering East China University of Science and TechnologyShanghai200237P.R.China Key Laboratory for Ultrafine Materials of Ministry of Education Frontiers Science Center for Materiobiology and Dynamic ChemistryShanghai Frontiers Science Center of Optogenetic Techniques for Cell MetabolismResearch Center for Biomedical Materials of Ministry of EducationSchool of Materials Science and EngineeringEast China University of Science and TechnologyShanghai200237P.R.China School of Biotechnology East China University of Science and TechnologyShanghai200237P.R.China

Polypeptoids are widely used in biological applications owing to their diverse functions and proteolytic *** type of polypeptoids,poly-N-methoxyethylglycine(P-Nmeg),has been found to possess remarkable hydrophilicity and notable properties in terms of protein,cell,and bacterial ***,the currently known synthesis methods of P-Nmeg include solid-phase synthesis,which is time-consuming and difficult to scale up,and N-substituted N-carboxyanhydride(NNCA)ring-opening polymerization,whose monomers were difficult to *** this study,we used the chemical stable Nmeg N-phenoxycarbonyl(NPC)as the monomer,which was obtained without the use of highly toxic reactants,such as phosgene or phosphorus halide,to synthesize P-Nmeg under open-vessel *** adding BnNH_(2) as an initiator at 80℃,we can obtain controllable short chain length P-Nmeg with narrow dispersity.

关键词： Open-vessel Polypeptoid synthesis Poly-N-methoxyethylglycine Stable monomer Narrow dispersity

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The environment,especially the minimum temperature,affects summer maize grain yield by regulating ear differentiation and grain development

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Journal of Integrative Agriculture 2024年第7期23卷 2227-2241页

作者： Jing Chen Baizhao Ren Bin Zhao Peng Liu Jiwang zhang State Key Laboratory of Crop Biology/College of Agronomy Shandong Agricultural UniversityTai’an 271018

Ear differentiation,grain development and their interaction with factors in the growing environment,such as temperature,solar radiation and precipitation,greatly influence grain number and grain weight,and ultimately affect summer maize *** this study,field experiments involving different sowing dates were conducted over three years to evaluate the effects of temperature factors,average solar radiation and total precipitation on the growth process,ear differentiation,fertilization characteristics,grain filling and yield of summer maize varieties with different growth *** hybrids were evaluated in Huang-Huai-Hai Plain(HHHP),China from 2018 to 2020 with five different sowing *** results showed that the grain yield formation of summer maize was strongly impacted by the environment from the silking(R1)to milking(R3)*** minimum temperature(AT_(min))was the key environmental factor that determined *** in the length of the growing season(r=–0.556,Pbortion rate on ear(R^(2)=0.437,Pbove 23°C during the R1–R3 stage and 20–21°C during the R1-R6 stage).Enhanced solar radiation and precipitation during R1–R6 increased the grain-filling rate(R^(2)=0.562,P<0.001 and R^(2)=0.229,P<0.05,respectively).Compared with short-season hybrids,full-season hybrids showed much greater suitability for a critical *** coordinated regulation of AT_(min),ear differentiation and grain development at the pre-and post-silking stages improved maize yie

关键词： sowing date hybrid maturity growing environment ear differentiation and grain development

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