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Coupling Coordination Analysis of Cropland Intensification and Agroecosystem Services:Evidence from Loess Plateau in Shaanxi Province,China
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作者 FU Shaowu FU Mengyu QIU Menglong 《Chinese Geographical Science》 SCIE CSCD 2024年第3期401-419,共19页
One of the greatest challenges in the agroecosystem is to improve cropland intensification while preserving agroecosystem services.While many studies have investigated the effect of cropland intensification on agroeco... One of the greatest challenges in the agroecosystem is to improve cropland intensification while preserving agroecosystem services.While many studies have investigated the effect of cropland intensification on agroecosystem service,the interactive coupling and coordination among these factors remain largely unexplored.In view of this,this study performed a case study of the Loess Plateau in Shaanxi Province,China and constructed comprehensive evaluation models to quantify the cropland intensification and agroecosystem service in this area.Balance analysis and the coupling coordination degree model were used to evaluate the interactive relationship between cropland intensification and agroecosystem service,and statistical analysis and spatial autocorrelation were used to analyze the spatial characteristics and potential mechanism of the coupling coordination.Results show that both the cropland intensification and agroecosystem service in the study area were relatively low yet gradually increased from 2000 to 2020.Agroecosystem service lag was identified as the dominant unbalanced development type.Improving the supply capacity of agroecosystem services plays a key role in the balanced development of cropland in the Loess Plateau.The coupling coordination degree between cropland intensification and agroecosystem service ranges from basic coordination to serious incoordination.Therefore,cropland intensification practices in the area should be optimized to enhance this coordination degree.An upward trend was also observed in the coupling coordination degree from2000 to 2020.The withdrawal of marginal cropland in the Grain for Green program is one of the most important reasons for this trend,especially for the northern region.Around 83.6%of the high-high clusters are concentrated in the southern region of the Loess Plateau,whereas 70.5%of the low-low clusters are distributed in the northern region.These clustering characteristics are mainly attributed to the environmental suitability of these areas for agriculture and their degree of economic development. 展开更多
关键词 cropland intensification agroecosystem services balance analysis coupling coordination degree Loess Plateau China
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Development Strategy of Urban Cultural Scene to Promote the Upgrading of Regional Cultural Consumption in Shaanxi
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作者 WANG Mengdie 《Journal of Landscape Research》 2023年第3期71-74,共4页
Regional cultural patterns and characteristics play a positive role in economic and social development.By planning and constructing cultural amenities and creating cultural scenes,the spatial quality and quality of li... Regional cultural patterns and characteristics play a positive role in economic and social development.By planning and constructing cultural amenities and creating cultural scenes,the spatial quality and quality of life in a region can be enhanced,facilitating the expansion of cultural consumption.Shaanxi,with its rich historical and cultural resources,positions the capital city of Xi’an as a“world historical city”,boasting a vast number of cultural amenities represented by“cultural facilities”,“cultural activities”,“cultural experiences”,and“cultural services”.The development of urban cultural scene,with the aim of promoting the upgrading of regional cultural consumption in Shaanxi,requires comprehensive planning and a multifaceted approach,particularly in integrating provincial cultural scenes,clarifying the positioning of cultural scenes,innovating cultural scene experience projects,creating cultural scene intellectual property(IP),and empowering cultural scenes through the application of science and technology. 展开更多
关键词 Cultural consumption Urban cultural scene Economic and social development Development strategy
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Grassland-type ecosystem stability in China differs under the influence of drought and wet events
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作者 CAO Wenyu BAI Jianjun YU Leshan 《Journal of Arid Land》 SCIE CSCD 2024年第5期615-631,共17页
Ecological stability is a core issue in ecological research and holds significant implications forhumanity. The increased frequency and intensity of drought and wet climate events resulting from climatechange pose a m... Ecological stability is a core issue in ecological research and holds significant implications forhumanity. The increased frequency and intensity of drought and wet climate events resulting from climatechange pose a major threat to global ecological stability. Variations in stability among different ecosystemshave been confirmed, but it remains unclear whether there are differences in stability within the sameterrestrial vegetation ecosystem under the influence of climate events in different directions and intensities.China's grassland ecosystem includes most grassland types and is a good choice for studying this issue.This study used the Standardized Precipitation Evapotranspiration Index-12 (SPEI-12) to identify thedirections and intensities of different types of climate events, and based on Normalized DifferenceVegetation Index (NDVI), calculated the resistance and resilience of different grassland types for 30consecutive years from 1990 to 2019 (resistance and resilience are important indicators to measurestability). Based on a traditional regression model, standardized methods were integrated to analyze theimpacts of the intensity and duration of drought and wet events on vegetation stability. The resultsshowed that meadow steppe exhibited the highest stability, while alpine steppe and desert steppe had thelowest overall stability. The stability of typical steppe, alpine meadow, temperate meadow was at anintermediate level. Regarding the impact of the duration and intensity of climate events on vegetationecosystem stability for the same grassland type, the resilience of desert steppe during drought was mainlyaffected by the duration. In contrast, the impact of intensity was not significant. However, alpine steppewas mainly affected by intensity in wet environments, and duration had no significant impact. Ourconclusions can provide decision support for the future grassland ecosystem governance. 展开更多
关键词 grassland ecosystem stability resistance RESILIENCE different climate types drought climate event wet climate event
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Endochondral ossification of hindlimbs in embryonic development of Japanese Quail(Coturnix japonica)
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作者 Xuan Li Yuxin Zhang Hongfeng Zhao 《Avian Research》 SCIE CSCD 2024年第1期123-132,共10页
The endochondral ossification of hindlimb is essential to a bird’s ability to stand,walk and fly.Most hindlimb is ossified in the embryos before hatching in precocial birds.However,the molecular mechanisms of hindlim... The endochondral ossification of hindlimb is essential to a bird’s ability to stand,walk and fly.Most hindlimb is ossified in the embryos before hatching in precocial birds.However,the molecular mechanisms of hindlimb ossification in birds is still unclear.Therefore,we tried to examine the process of hindlimb ossification and its molecular regulation by using an animal model—Japanese Quail(Coturnix japonica).We selected four critical stages(Embryo Day:E6,E8,E12 and E16) of skeletal development of embryonic quails for hindlimb skeleton staining to show the process of endochondral ossification and to examine the molecular regulation of endochondral osteogenesis by RNA-Seq analysis.The results showed that ossification became increased with embryonic development and most hindlimb was ossified before hatching.RNA-Seq analysis revealed that various signaling pathways were involved with endochondral ossification with thyroid hormone signaling and WNT signaling pathway particularly enriched.Moreover,the expression levels of 42 genes were continuously upregulated and 14 genes were continuously downregulated from E6 to E16.The present study might provide new insights into complex molecular mechanisms in regulation of endochondral ossification. 展开更多
关键词 Embryos HINDLIMB OSSIFICATION PRECOCIAL TRANSCRIPTOMICS
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Influence of varied drought types on soil conservation service within the framework of climate change:insights from the Jinghe River Basin,China
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作者 BAI Jizhou LI Jing +4 位作者 RAN Hui ZHOU Zixiang DANG Hui ZHANG Cheng YU Yuyang 《Journal of Arid Land》 SCIE CSCD 2024年第2期220-245,共26页
Severe soil erosion and drought are the two main factors affecting the ecological security of the Loess Plateau,China.Investigating the influence of drought on soil conservation service is of great importance to regio... Severe soil erosion and drought are the two main factors affecting the ecological security of the Loess Plateau,China.Investigating the influence of drought on soil conservation service is of great importance to regional environmental protection and sustainable development.However,there is little research on the coupling relationship between them.In this study,focusing on the Jinghe River Basin,China as a case study,we conducted a quantitative evaluation on meteorological,hydrological,and agricultural droughts(represented by the Standardized Precipitation Index(SPI),Standardized Runoff Index(SRI),and Standardized Soil Moisture Index(SSMI),respectively)using the Variable Infiltration Capacity(VIC)model,and quantified the soil conservation service using the Revised Universal Soil Loss Equation(RUSLE)in the historical period(2000-2019)and future period(2026-2060)under two Representative Concentration Pathways(RCPs)(RCP4.5 and RCP8.5).We further examined the influence of the three types of drought on soil conservation service at annual and seasonal scales.The NASA Earth Exchange Global Daily Downscaled Projections(NEX-GDDP)dataset was used to predict and model the hydrometeorological elements in the future period under the RCP4.5 and RCP8.5 scenarios.The results showed that in the historical period,annual-scale meteorological drought exhibited the highest intensity,while seasonal-scale drought was generally weakest in autumn and most severe in summer.Drought intensity of all three types of drought will increase over the next 40 years,with a greater increase under the RCP4.5 scenario than under the RCP8.5 scenario.Furthermore,the intra-annual variation in the drought intensity of the three types of drought becomes smaller under the two future scenarios relative to the historical period(2000-2019).Soil conservation service exhibits a distribution pattern characterized by high levels in the southwest and southeast and lower levels in the north,and this pattern has remained consistent both in the historical and future periods.Over the past 20 years,the intra-annual variation indicated peak soil conservation service in summer and lowest level in winter;the total soil conservation of the Jinghe River Basin displayed an upward trend,with the total soil conservation in 2019 being 1.14 times higher than that in 2000.The most substantial impact on soil conservation service arises from annual-scale meteorological drought,which remains consistent both in the historical and future periods.Additionally,at the seasonal scale,meteorological drought exerts the highest influence on soil conservation service in winter and autumn,particularly under the RCP4.5 and RCP8.5 scenarios.Compared to the historical period,the soil conservation service in the Jinghe River Basin will be significantly more affected by drought in the future period in terms of both the affected area and the magnitude of impact.This study conducted beneficial attempts to evaluate and predict the dynamic characteristics of watershed drought and soil conservation service,as well as the response of soil conservation service to different types of drought.Clarifying the interrelationship between the two is the foundation for achieving sustainable development in a relatively arid and severely eroded area such as the Jinghe River Basin. 展开更多
关键词 meteorological drought hydrological drought agricultural drought soil conservation service Variable Infiltration Capacity(VIC)model Revised Universal Soil Loss Equation(RUSLE) Jinghe River Basin
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Microscopic mechanism of plasmon-mediated photocatalytic H_(2) splitting on Ag-Au alloy chain
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作者 宋玉慧 芦一瑞 +5 位作者 郭阿鑫 曹逸飞 李金萍 付正坤 严蕾 张正龙 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第3期322-326,共5页
Alloy nanostructures supporting localized surface plasmon resonances has been widely used as efficient photocatalysts,but the microscopic mechanism of alloy compositions enhancing the catalytic efficiency is still unc... Alloy nanostructures supporting localized surface plasmon resonances has been widely used as efficient photocatalysts,but the microscopic mechanism of alloy compositions enhancing the catalytic efficiency is still unclear.By using time-dependent density functional theory(TDDFT),we analyze the real-time reaction processes of plasmon-mediated H_(2) splitting on linear Ag-Au alloy chains when exposed to femtosecond laser pulses.It is found that H_(2) splitting rate depends on the position and proportion of Au atoms in alloy chains,which indicates that specially designed Ag-Au alloy is more likely to induce the reaction than pure Ag chain.Especially,more electrons directly transfer from the alloy chain to the anti-bonding state of H_(2),thereby accelerating the H_(2) splitting reaction.These results establish a theoretical foundation for comprehending the microscopic mechanism of plasmon-induced chemical reaction on the alloy nanostructures. 展开更多
关键词 PLASMON PHOTOCATALYSIS time-dependent density functional theory(TDDFT)
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Plasmon-induced nonlinear response on gold nanoclusters
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作者 宋玉慧 曹逸飞 +5 位作者 黄思晨 李凯超 杜如海 严蕾 付正坤 张正龙 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第4期36-39,共4页
The plasmon-induced nonlinear response has attracted great attention in micro-nano optics and optoelectronics applications,yet the underlying microscopic mechanism remains elusive.In this study,the nonlinear response ... The plasmon-induced nonlinear response has attracted great attention in micro-nano optics and optoelectronics applications,yet the underlying microscopic mechanism remains elusive.In this study,the nonlinear response of gold nanoclusters when exposed to a femtosecond laser pulse was investigated using time-dependent density functional theory.It was observed that the third-order tunneling current was augmented in plasmonic dimers,owing to a greater number of electrons in the dimer being excited from occupied to unoccupied states.These findings provide profound theoretical insights and enable the realization of accurate regulation and control of nonlinear effects induced by plasmons at the atomic level. 展开更多
关键词 PLASMON nonlinear optics time-dependent density functional theory(TDDFT)
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Behaviors of cavitation bubbles driven by high-intensity ultrasound
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作者 黄晨阳 李凡 +5 位作者 冯释毅 王成会 陈时 胡静 何芯蕊 宋家凯 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第2期394-404,共11页
In a multi-bubble system, the bubble behavior is modulated by the primary acoustic field and the secondary acoustic field. To explore the translational motion of bubbles in cavitation liquids containing high-concentra... In a multi-bubble system, the bubble behavior is modulated by the primary acoustic field and the secondary acoustic field. To explore the translational motion of bubbles in cavitation liquids containing high-concentration cavitation nuclei,evolutions of bubbles are recorded by a high-speed camera, and translational trajectories of several representative bubbles are traced. It is found that translational motion of bubbles is always accompanied by the fragmentation and coalescence of bubbles, and for bubbles smaller than 10 μm, the possibility of bubble coalescence is enhanced when the spacing of bubbles is less than 30 μm. The measured signals and their spectra show the presence of strong negative pressure, broadband noise,and various harmonics, which implies that multiple interactions of bubbles appear in the region of high-intensity cavitation.Due to the strong coupling effect, the interaction between bubbles is random. A simplified triple-bubble model is developed to explore the interaction patterns of bubbles affected by the surrounding bubbles. Patterns of bubble interaction, such as attraction, repulsion, stable spacing, and rebound of bubbles, can be predicted by the theoretical analysis, and the obtained results are in good agreement with experimental observations. Mass exchange between the liquid and bubbles as well as absorption in the cavitation nuclei also plays an important role in multi-bubble cavitation, which may account for the weakening of the radial oscillations of bubbles. 展开更多
关键词 ultrasonic cavitation multi-bubble system translational motion of bubbles
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Ecological effect of the plantation of Sabina vulgaris in the Mu Us Sandy Land,China
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作者 NAN Weige DONG Zhibao +2 位作者 ZHOU Zhengchao LI Qiang CHEN Guoxiang 《Journal of Arid Land》 SCIE CSCD 2024年第1期14-28,共15页
Vegetation restoration through artificial plantation is an effective method to combat desertification,especially in arid and semi-arid areas.This study aimed to explore the ecological effect of the plantation of Sabin... Vegetation restoration through artificial plantation is an effective method to combat desertification,especially in arid and semi-arid areas.This study aimed to explore the ecological effect of the plantation of Sabina vulgaris on soil physical and chemical properties on the southeastern fringe of the Mu Us Sandy Land,China.We collected soil samples from five depth layers(0-20,20-40,40-60,60-80,and 80-100 cm)in the S.vulgaris plantation plots across four plantation ages(4,7,10,and 16 years)in November 2019,and assessed soil physical(soil bulk density,soil porosity,and soil particle size)and chemical(soil organic carbon(SOC),total nitrogen(TN),available nitrogen(AN),available phosphorus(AP),available potassium(AK),cation-exchange capacity(CEC),salinity,p H,and C/N ratio)properties.The results indicated that the soil predominantly consisted of sand particles(94.27%-99.67%),with the remainder being silt and clay.As plantation age increased,silt and very fine sand contents progressively rose.After 16 years of planting,there was a marked reduction in the mean soil particle size.The initial soil fertility was low and declined from 4 to 10 years of planting before witnessing an improvement.Significant positive correlations were observed for the clay,silt,and very fine sand(mean diameter of 0.000-0.100 mm)with SOC,AK,and p H.In contrast,fine sand and medium sand(mean diameter of 0.100-0.500 mm)showed significant negative correlations with these indicators.Our findings ascertain that the plantation of S.vulgaris requires 10 years to effectively act as a windbreak and contribute to sand fixation,and needs 16 years to improve soil physical and chemical properties.Importantly,these improvements were found to be highly beneficial for vegetation restoration in arid and semi-arid areas.This research can offer valuable insights for the protection and restoration of the vegetation ecosystem in the sandy lands in China. 展开更多
关键词 Sabina vulgaris plantation age soil physical and chemical properties soil particle size soil fertility vegetation restoration Mu Us Sandy Land
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Ultrafast dynamics in photo-excited Mott insulator Sr_(3)Ir_(2)O_7 at high pressure
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作者 尹霞 张建波 +6 位作者 王东 Takeshi Nakagawa 夏春生 张曹顺 郭伟程 昌峻 丁阳 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第1期149-155,共7页
High-pressure ultrafast dynamics,as a new crossed research direction,are sensitive to subtle non-equilibrium state changes that might be unresolved by equilibrium states measurements,providing crucial information for ... High-pressure ultrafast dynamics,as a new crossed research direction,are sensitive to subtle non-equilibrium state changes that might be unresolved by equilibrium states measurements,providing crucial information for studying delicate phase transitions caused by complex interactions in Mott insulators.With time-resolved transient reflectivity measurements,we identified the new phases in the spin–orbit Mott insulator Sr_(3)Ir_(2)O_7 at 300 K that was previously unidentified using conventional approaches such as x-ray diffraction.Significant pressure-dependent variation of the amplitude and lifetime obtained by fitting the reflectivity?R/R reveal the changes of electronic structure caused by lattice distortions,and reflect the critical phenomena of phase transitions.Our findings demonstrate the importance of ultrafast nonequilibrium dynamics under extreme conditions for understanding the phase transition of Mott insulators. 展开更多
关键词 ultrafast dynamics high pressure phase transition Mott insulator
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SOME PROPERTIES OF THE INTEGRATION OPERATORS ON THE SPACES F(p,q,s)
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作者 陈家乐 《Acta Mathematica Scientia》 SCIE CSCD 2024年第1期173-188,共16页
We study the closed range property and the strict singularity of integration operators acting on the spaces F(p,pα-2,s).We completely characterize the closed range property of the Volterra companion operator I_(g)on ... We study the closed range property and the strict singularity of integration operators acting on the spaces F(p,pα-2,s).We completely characterize the closed range property of the Volterra companion operator I_(g)on F(p,pα-2,s),which generalizes the existing results and answers a question raised in[A.Anderson,Integral Equations Operator Theory,69(2011),no.1,87-99].For the Volterra operator J_(g),we show that,for 0<α≤1,J_(g)never has a closed range on F(p,pα-2,s).We then prove that the notions of compactness,weak compactness and strict singularity coincide in the case of J_(g)acting on F(p,p-2,s). 展开更多
关键词 integration operator closed range property strict singularity
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Progress in the research on organic piezoelectric catalysts for dye decomposition
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作者 Zhaoning Yang Xiaoxin Shu +3 位作者 Di Guo Jing Wang Hui Bian Yanmin Jia 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2024年第2期245-260,共16页
Organic contaminants have posed a direct and substantial risk to human wellness and the environment.In recent years,piezo-electric catalysis has evolved as a novel and effective method for decomposing these contaminan... Organic contaminants have posed a direct and substantial risk to human wellness and the environment.In recent years,piezo-electric catalysis has evolved as a novel and effective method for decomposing these contaminants.Although piezoelectric materials offer a wide range of options,most related studies thus far have focused on inorganic materials and have paid little attention to organic materi-als.Organic materials have advantages,such as being lightweight,inexpensive,and easy to process,over inorganic materials.Therefore,this paper provides a comprehensive review of the progress made in the research on piezoelectric catalysis using organic materials,high-lighting their catalytic efficiency in addressing various pollutants.In addition,the applications of organic materials in piezoelectric cata-lysis for water decomposition to produce hydrogen,disinfect bacteria,treat tumors,and reduce carbon dioxide are presented.Finally,fu-ture developmental trends regarding the piezoelectric catalytic potential of organic materials are explored. 展开更多
关键词 piezoelectric catalysis piezoelectric material dye decomposition organic materials
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Research on the Audio Publishing of Classical Books Based on the Theory of Business Model Canvas: Taking Romance of the Three Kingdoms in Digital Audio Platforms as an Example
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作者 Ding Qin Liu Mengzhi 《Contemporary Social Sciences》 2024年第1期58-74,共17页
Visual media have dominated sensory communications for decades,and the resulting“visual hegemony”leads to the call for the“auditory return”in order to achieve a holistic balance in cultural acceptance.Romance of t... Visual media have dominated sensory communications for decades,and the resulting“visual hegemony”leads to the call for the“auditory return”in order to achieve a holistic balance in cultural acceptance.Romance of the Three Kingdoms,a classic literary work in China,has received significant attention and promotion from leading audio platforms.However,the commercialization of digital audio publishing faces unprecedented challenges due to the mismatch between the dissemination of long-form content on digital audio platforms and the current trend of short and fast information reception.Drawing on the Business Model Canvas Theory and taking Romance of the Three Kingdoms as the main focus of analysis,this paper argues that the construction of a business model for the audio publishing of classical books should start from three aspects:the user evaluation of digital audio platforms,the establishment of value propositions based on the“creative transformation and innovative development”principle,and the improvement of the audio publishing infrastructure to ensure the healthy operation and development of the digital audio platforms and consequently improve their current state of development and expand the boundaries of cultural heritage. 展开更多
关键词 Romance of the Three Kingdoms audio publishing Business Model Canvas digital audio platforms
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Tunable spectral continuous shift of high-order harmonic generation in atoms by a plasmon-assisted shaping pulse
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作者 王源 李玉龙 +7 位作者 乔月 高娜 郭福明 陈洲 赫兰海 杨玉军 赵曦 王俊 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第3期433-440,共8页
We delve into the phenomenon of high-order harmonic generation within a helium atom under the influence of a plasmon-assisted shaping pulse.Our findings reveal an intriguing manipulation of the frequency peak position... We delve into the phenomenon of high-order harmonic generation within a helium atom under the influence of a plasmon-assisted shaping pulse.Our findings reveal an intriguing manipulation of the frequency peak position in the harmonic emission by adjusting the absolute phase parameter within the frequency domain of the shaping pulse.This phenomenon holds potential significance for experimental setups necessitating precisely tuned single harmonics.Notably,we observe a modulated shift in the created harmonic photon energy,spanning an impressive range of 1.2 eV.This frequency peak shift is rooted in the asymmetry exhibited by the rising and falling edges of the laser pulse,directly influencing the position of the peak frequency emission.Our study quantifies the dependence of this tuning range and the asymmetry of the laser pulse,offering valuable insights into the underlying mechanisms driving this phenomenon.Furthermore,our investigation uncovers the emergence of semi-integer order harmonics as the phase parameter is altered.We attribute this discovery to the intricate interference between harmonics generated by the primary and secondary return cores.This observation introduces an innovative approach for generating semi-integer order harmonics,thus expanding our understanding of high-order harmonic generation.Ultimately,our work contributes to the broader comprehension of complex phenomena in laser-matter interactions and provides a foundation for harnessing these effects in various applications,particularly those involving precise spectral control and the generation of unique harmonic patterns. 展开更多
关键词 high-order harmonic semi-integer-order spectra shift inhomogeneous field
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Parallel Vision ■ Image Synthesis/Augmentation
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作者 Wenwen Zhang Wenbo Zheng +1 位作者 Qiang Li Fei-Yue Wang 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2024年第3期782-784,共3页
Dear Editor,Scene understanding is an essential task in computer vision.The ultimate objective of scene understanding is to instruct computers to understand and reason about the scenes as humans do.Parallel vision is ... Dear Editor,Scene understanding is an essential task in computer vision.The ultimate objective of scene understanding is to instruct computers to understand and reason about the scenes as humans do.Parallel vision is a research framework that unifies the explanation and perception of dynamic and complex scenes. 展开更多
关键词 instru EXPLANATION COMPUTER
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Effect of Vacancy Defects on the Properties of CoS_(2) and FeS_(2)
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作者 冯中营 ZHANG Jianmin +3 位作者 WANG Xiaowei YANG Wenjin JING Yinlan YANG Yan 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第3期627-638,共12页
In order to explore the effect of vacancy defects on the structural,electronic,magnetic and optical properties of CoS_(2) and FeS_(2),first-principles calculation method was used to investigate the alloys.The calculat... In order to explore the effect of vacancy defects on the structural,electronic,magnetic and optical properties of CoS_(2) and FeS_(2),first-principles calculation method was used to investigate the alloys.The calculated results of materials without vacancy are consistent with those reported in the literatures,while the results of materials with vacancy defect were different from those of literatures due to the difference vacancy concentration.The Co vacancy defect hardly changes the half-metallic characteristic of CoS_(2).The Fe vacancy defect changes FeS_(2) from semiconductor to half-metal,and the bottom of the spin-down conduction band changes from the p orbital state of S to the d(t_(2g))orbital state of Fe,while the top of the valence band remains the d orbital d(eg)state of Fe.The half-metallic Co vacancy defects of CoS_(2) and Fe vacancy defects of FeS_(2) are expected to be used in spintronic devices.S vacancy defects make both CoS_(2) and FeS_(2) metallic.Both the Co and S vacancy defects lead to the decrease of the magnetic moment of CoS_(2),while both the Fe and S vacancy defects lead to the obvious magnetic property of FeS_(2).Vacancy defects enhance the absorption coefficient of infrared band and long band of visible light obviously,and produce obvious red shift phenomenon,which is expected to be used in photoelectric devices. 展开更多
关键词 cobalt disulfide iron disulfide vacancy defect fist principles
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Patterns and drivers of plant sexual systems in the dry-hot valley region of southwestern China
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作者 Rong Ma Qi Xu +3 位作者 Yongqian Gao Deli Peng Hang Sun Bo Song 《Plant Diversity》 SCIE CAS CSCD 2024年第2期158-168,共11页
Sexual systems play important roles in angiosperm evolution and exhibit substantial variations among different floras. Thus, studying their evolution in a whole flora is crucial for understanding the formation and mai... Sexual systems play important roles in angiosperm evolution and exhibit substantial variations among different floras. Thus, studying their evolution in a whole flora is crucial for understanding the formation and maintenance of plant biodiversity and predicting its responses to environmental change. In this study, we determined the patterns of plant sexual systems and their associations with geographic elements and various life-history traits in dry-hot valley region of southwestern China, an extremely vulnerable ecosystem. Of the 3166 angiosperm species recorded in this area, 74.5% were hermaphroditic,13.5% were monoecious and 12% were dioecious, showing a high incidence of diclinous species. Diclinous species were strongly associated with tropical elements, whereas hermaphroditic species were strongly associated with temperate and cosmopolitan elements. We also found that hermaphroditism was strongly associated with showy floral displays, specialist entomophily, dry fruits and herbaceous plants.Dioecy was strongly associated with inconspicuous, pale-colored flowers, generalist entomophily, fleshy fruits, and woody plants, whereas monoecy was strongly associated with inconspicuous, pale-colored flowers, anemophily, dry fruits, and herbaceous plants. In addition, hermaphroditic species with generalist entomophily tended to flower in the dry season, whereas diclinous species with specialist entomophily tended to flower in the rainy season. However, independent of sexual systems, plants that produce dry fruits tended to flower in the rainy season and set fruits in the dry season, but the opposite pattern was found for fleshy fruit-producing plants. Our results suggest that in the dry-hot valleys, plant sexual systems are associated with geographic elements as well as various life-history traits that are sensitive to environmental change. 展开更多
关键词 Floral traits Fruit type Growth form Pollination system Reproductive phenology
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Influence of Transportation Accessibility on Urban-rural Income Disparity and Its Spatial Heterogeneity
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作者 HUANG Xiaoyan KANG Chenchen +1 位作者 YIN Chun TANG Junqing 《Chinese Geographical Science》 SCIE CSCD 2024年第3期453-467,共15页
Transportation accessibility has been treated as an important means of reducing the urban-rural income disparity.However,only a few studies have examined the effects of different types of transportation accessibility ... Transportation accessibility has been treated as an important means of reducing the urban-rural income disparity.However,only a few studies have examined the effects of different types of transportation accessibility on urban-rural income disparity and their spatial heterogeneity.Based on data from 285 prefecture-level(and above)Chinese cities in 2000,2005,2010,2015,and 2020,this study uses spatial econometric models to examine how highway accessibility and railway accessibility influence the urban-rural income disparity and to identify their spatial heterogeneity.The result reveals that highway accessibility and railway accessibility have‘coreperiphery’ring-like circle structures.The urban-rural income disparity exhibits strong spatial clustering effects.Both highway accessibility and railway accessibility are negatively associated with urban-rural income disparity,and the former having a greater effect size.Moreover,there is a substitution effect between highway accessibility and railway accessibility in the whole sample.Furthermore,these associations differ in geographic regions.In the central region,highway accessibility is more important in reducing the urban-rural income disparity,but its effect is weakened with the increase of railway accessibility.In the western region,railway accessibility has a larger effect on narrowing the urban-rural income disparity,and this effect is strengthened by the increase of highway accessibility.We conclude that improving transportation accessibility is conducive to reducing the urban-rural income disparity but its effect is spatial heterogenetic.Highways and railways should be developed in a coordinated manner to promote an integrated transport network system. 展开更多
关键词 transport accessibility income gap regional divergence spatial heterogeneity urban and rural areas China
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Dried earth layers of artificial forestland in the Loess Plateau of Shaanxi Province 被引量:17
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作者 ZHAO Jingbo DU Juan CHEN Baoqun 《Journal of Geographical Sciences》 SCIE CSCD 2007年第1期114-126,共13页
由在 Shaanxi 省的黄土高原深处决定在 0 和 6 m 之间的人工的林地的地球潮湿内容,潮湿内容,分发和弄干的地球层的形成原因的垂直变化被研究。结果证明平均潮湿内容是在在在 Guanzhong 的超过 10 年鈥檚 生长的人工的森林下面的 2 和 ... 由在 Shaanxi 省的黄土高原深处决定在 0 和 6 m 之间的人工的林地的地球潮湿内容,潮湿内容,分发和弄干的地球层的形成原因的垂直变化被研究。结果证明平均潮湿内容是在在在 Guanzhong 的超过 10 年鈥檚 生长的人工的森林下面的 2 和 4 m 之间的 9.3% 鈥 ?.5% 平凡、长期的弱弄干的地球层被开发它证明弄干的地球层在黄土高原上广泛地是分布式的。弄干的陆地层的南部的边界到达了 Qinling 山脉的北脚。当降水到达 600 公里时,在在超过 10 岁的人工的森林下面的 2 和 4 m 之间有弱弄干的地球层。当降水在 400 和 500 公里之间时,有中等弄干的地球层。当降水在 800 公里上面时,没有弄干的地球层。在草地土地,玉米陆地和在黄土高原的中央、南部的部分的人工的林地的不到 5 岁下面没有弄干的地球层。在柏树森林下面的弄干的地球层的发展比阔叶的森林弱。在一样的气候的条件下面,在黄土台地下面的弄干的地球层的发展是将近在象第二 and 的一样的水平第三个河平台。弄干的地球层在膜水地区,和埋葬的深度发展了是小的,运动速度在黄土高原是慢的,它是弄干的地球层的形成的直接的水因素,当树年龄和树种类的差别是消费了许多潮湿的植物因素时。从水和膜在 Guanzhong 平原浇的严肃的深度,弄干的地球层的形成原因主要由于自然因素,是清楚的。弄干的层通常在消费了太多潮湿的中年的人工的林地发展,它是在 subhumid 和半干旱的地区的地球潮湿的一般特性。弄干的层 doesn 鈥檛 的外观证明森林 doesn 鈥檛 在这个区域发展;这被取决于他们的发展紧张。在弄干的地球层微弱地发展了的地方,消费更少的水的中国白杨,蝗虫树和中国 scholartree 的人工的森林能在区域被种,但是在弄干的地球层强烈地发展了的地方,不能在区域被种。 展开更多
关键词 地球 干燥 人工造林 黄土高原
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Changes in Ecosystem Service Values on the Loess Plateau in Northern Shaanxi Province,China 被引量:9
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作者 LI Jing REN Zhi-yuan 《Agricultural Sciences in China》 CAS CSCD 2008年第5期606-614,共9页
The Loess Plateau in northern Shaanxi Province of China covers Yulin,Yan'an,and Tongchuan cities mainly. The kind of physiognomy is complicated and various,including the transitional region of the sand and wind,th... The Loess Plateau in northern Shaanxi Province of China covers Yulin,Yan'an,and Tongchuan cities mainly. The kind of physiognomy is complicated and various,including the transitional region of the sand and wind,the hilly-gully fragile region,the pimple mound region from North to South. Large-scale land reclamation projects that are severely affecting these ecosystems have been implemented. In this paper,we reported an investigation to the changes in land use and ecosystem services on the Loess Plateau in northern Shaanxi Province from 1978 to 2000. We used three LANDSAT TM and/or ETM data sets to estimate the changes in the size of five land-cover/land-use categories,and we also used previously published value coefficients to estimate the changes in the value of ecosystem services delivered by each land category. Finally,we ranked the contribution of various ecosystem functions to the overall value of the ecosystem services. we have estimated that the annual value of the ecosystem services is 56.95 billon RMB yuan in the Loess Plateau in northern Shaanxi Province in 2000. In the region,from 1978 to 2000,the economic value of the fixing carbon was higher,the economic value of water conservation was the lowest,but the economic value of the NPP,fixing carbon,and supplying oxygen accounted for above ninety percent of the total value,obviously the vegetation created the biggest ecosystem service value. We can conclude that future land-use policy formulation should give precedence to the conservation of these ecosystems over uncontrolled reclamation,and that further land reclamation should be based on rigorous environmental impact analyses. 展开更多
关键词 生态系统 黄土高原 陕西 中国
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