期刊文献+
共找到285,916篇文章
< 1 2 250 >
每页显示 20 50 100
Rigorous verification of quantum contextuality from anomalous weak value
1
作者 Wei-Qian Zhao Si-Nan Pang +3 位作者 Zi-Fu Su Tian-Ming Zhao Jin-Dong Wang Ya-Fei Yu 《Chinese Physics B》 2026年第2期306-313,共8页
Weak measurement offers a powerful framework for probing nonclassical features of quantum mechanics,with anomalous weak values serving as operational signatures of contextuality.While the anomalous weak value verifica... Weak measurement offers a powerful framework for probing nonclassical features of quantum mechanics,with anomalous weak values serving as operational signatures of contextuality.While the anomalous weak value verification of quantum contextuality has been predominantly investigated in the single-photon regime and analyzed under approximation condition of infinitesimally small perturbation strength.This study releases the approximation condition and takes into account the impact of perturbation strength on the rigor of the verification.And the investigation on the verification of contextuality is extended to the multi-photon scenarios for observing the influence of the correlation between photons on the verification.Without the limitation of infinitesimally small probability of disturbance,anomalous weak values are identified as necessary for contextuality to emerge,thereby refining the criterion proposed by Pusey[Phys.Rev.Lett.113200401(2014)].In the multi-photon scenarios,the emergence of contextuality also depends strongly on both the photon number and the photon-number distribution state.In particular,contextuality is found to be maximized when the single-photon component dominates and the second-order correlation is lower.These results highlight the critical role of photon statistics in experimental tests of contextuality via anomalous weak values. 展开更多
关键词 quantum measurement CONTEXTUALITY weak measurement weak values
原文传递
Assessment of pan-immune-inflammation value as a novel marker of proliferative diabetic retinopathy stage
2
作者 Ozlem Candan Gözde Orman +1 位作者 NurtenÜnlü Güner Uney 《International Journal of Ophthalmology(English edition)》 2026年第3期517-525,共9页
AIM:To evaluate the predictive value of pan-immuneinflammation value(PIV)in the diagnosis of proliferative diabetic retinopathy(PDR)and its association with the stage of PDR.METHODS:This observational case-control stu... AIM:To evaluate the predictive value of pan-immuneinflammation value(PIV)in the diagnosis of proliferative diabetic retinopathy(PDR)and its association with the stage of PDR.METHODS:This observational case-control study included participants who underwent routine complete blood count testing.Inflammation-related indices,including neutrophil-to-lymphocyte ratio,systemic immune-inflammation index(SII),and PIV,were derived and analyzed.Receiver operating characteristic curve(ROC)analysis was applied to assess the diagnostic performance of these indices in distinguishing patients with PDR,with sensitivity,specificity,area under ROC,and optimal threshold values calculated.In addition,binary logistic regression analysis was performed to evaluate the association between inflammatory indices and PDR stage.RESULTS:This study included 205 patients:60 with diabetes without retinopathy(mean age:61.81±10.76y),80 with PDR(mean age:61.63±10.03y)and 65 healthy controls(mean age:59.52±5.88y).The PDR group had significantly higher white blood cell(WBC,P<0.001),monocyte(MONO,P=0.009)and neutrophil(NEU)counts(P<0.001).SII and PIV had the highest sensitivity and area under ROC for predicting patients with PDR(0.822,0.846,respectively).The optimal cut-off values for discriminating patients with PDR were determined to be>527.12 and>299.08 for SII and PIV,respectively.The logistic regression analysis demonstrated that a decrease in lymphocyte(LYM)count and an increase in platelet count(PLT),glycated haemoglobin(HbA1c),SII,and PIV were all significantly associated with the development of high-risk PDR(all P<0.05).PIV was more stable than independent MONO,LYM,PLT and NEU levels in predicting both the diagnosis and stage of PDR.The optimal cut-off value for PIV to discriminate patients with high-risk PDR was found to be>345.87 area under ROC=0.871,with sensitivity of 0.827 and specificity of 0.812.CONCLUSION:PIV is a reliable,valuable,and inexpensive blood index that can be used for early detection and staging of PDR.PIV may therefore be essential to be used for the follow-up of diabetic patients. 展开更多
关键词 pan-immune-inflammation value proliferative diabetic retinopathy systemic immuneinflammation index monocyte-related inflammation systemic inflammation
原文传递
Social Network and Value Chain Integration:Unraveling the Formation and Evolution of Meizhou Pomelo Industry Cluster in China
3
作者 YANG Ren LIN Yuancheng ZHANG Xin 《Chinese Geographical Science》 2026年第2期239-255,共17页
The shift toward specialized and large-scale agricultural production has spurred the emergence of agricultural clusters as key forces of rural vitalization and sustainable development.This paper explored the formation... The shift toward specialized and large-scale agricultural production has spurred the emergence of agricultural clusters as key forces of rural vitalization and sustainable development.This paper explored the formation and evolution of Meizhou pomelo industry cluster in China,focusing on its role in restructuring rural socio-economic systems and integrating the whole value chains.Based on a case study employing qualitative methods such as in-depth interviews and participatory observation,the agricultural cluster evolution of Meizhou pomelo was categorized into three key phases of initial decentralization,self-organized scaling,and reorganized clustering.Geographical proximity and industrial agglomeration constitute the physical foundation,while vertical/horizontal linkages,technologic-al innovation,and policy support enhance competitiveness.Special mechanisms emerge through localized social networks,farmer co-operatives’activation,and cross-regional market expansion.The cluster’s impact is manifested in the shift from extensive to standard-ized and modernized production,diversified and flexible livelihood of farmers,and the integration of agriculture with industry and ser-vices.The development of the whole value chain based on agricultural cluster represents a critical pathway for achieving agricultural modernization,encompassing both internal and external value chain optimization.Through quality assurance systems,product diversi-fication strategies,operational efficiency improvements,and brand enhancement,these clusters amplify product value propositions and market competitiveness.This systemic approach facilitates supply-demand coordination,enables resource synergies,and optimizes eco-nomic returns across the horizontal and vertical value chain.This paper argues that agricultural clusters serve as strategic catalysts for sustainable rural development by reconstructing local production systems,fostering innovation ecosystems,and aligning agricultural modernization.It contributes to debates on rural vitalization by demonstrating how agricultural clustering can reconfigure rural areas as hubs of ecological modernization,rather than mere urban peripheries. 展开更多
关键词 agricultural cluster sustainable rural development agricultural systems social network whole value chain China
在线阅读 下载PDF
The five major textile and apparel industry clusters in Xinjiang have achieved an output value exceeding 220 billion yuan
4
作者 Qiu Shuchen 《China Textile》 2026年第1期34-35,共2页
In the Tianshan region,a complete textile industry chain has been established,covering the entire process from cotton cultivation and chemical fiber production,through spinning,weaving,dyeing,and finishing,and further... In the Tianshan region,a complete textile industry chain has been established,covering the entire process from cotton cultivation and chemical fiber production,through spinning,weaving,dyeing,and finishing,and further extending to apparel,home textiles,and industrial textiles.In November 2025,the first list of five characteristic textile and apparel industry clusters in Xinjiang was officially announced,marking a new stage in the clustering of Xinjiang's textile and apparel industry.Data shows that the total output value of Xinjiang's cotton and textile and apparel industry chain has exceeded 220 billion yuan.With the nation's largest cotton production,a complete industrial chain system,and strong synergistic effects,Xinjiang has become a leading and highly competitive textile industry hub in China. 展开更多
关键词 clustering XINJIANG cotton production apparel industry chemical fiber industrial chain textile industry output value
在线阅读 下载PDF
Pursuing Emotional Value
5
《ChinAfrica》 2026年第3期60-61,共2页
The Double Take column looks at a single topic from an African and Chinese perspective.This month,we discuss how to understand the growing emphasis on emotional returns among young people.Emotional value has emerged a... The Double Take column looks at a single topic from an African and Chinese perspective.This month,we discuss how to understand the growing emphasis on emotional returns among young people.Emotional value has emerged as a central force shaping youth decision-making across work,consumption,relationships and lifestyle choices.Unlike traditional economic rationality that prioritises income and material security,emotional value focuses on how choices make individuals feel and how they align with personal meaning.This shift is particularly evident in rapidly transforming societies such as China and Ghana,where economic restructuring,globalisation and social change have reshaped pathways to adulthood. 展开更多
关键词 youth decision making emotional returns emotional value material security INCOME WORK CONSUMPTION economic rationality
原文传递
A Study on the Form,Material,and Cultural Value of the Rosewood Four-Head Official’s Cap Chair With Golden Flecks:A Case Study of the Inscribed Piece by Wang Shixiang
6
作者 HUANG Yun LIN Hai-tao 《Journal of Literature and Art Studies》 2026年第1期43-46,共4页
Ming-style furniture represents the pinnacle of Chinese traditional furniture,with the four-head official’s cap chair standing out as a representative category due to its classic form and cultural connotations.This p... Ming-style furniture represents the pinnacle of Chinese traditional furniture,with the four-head official’s cap chair standing out as a representative category due to its classic form and cultural connotations.This paper takes a specific rosewood four-head official’s cap chair inscribed by Wang Shixiang as the research subject,employing a tripartite approach of form analysis,material examination,and inscription interpretation.The chair strictly adheres to the classic form of Ming-style four-head official’s cap chairs,embodying the Ming Dynasty design philosophy of“the unity of function and aesthetics”.The scarcity and unique grain pattern of the golden-flecked rosewood(Zitan)endow it with the status of“gold among woods”.Wang Shixiang’s inscription binds the furniture to the cultural essence of“the charm of the Ming Dynasty”,transforming it into“heritable cultural heritage”.This paper provides a new perspective for the case study of Ming-style furniture and offers theoretical reference for the contemporary inheritance of traditional craftsmanship. 展开更多
关键词 Ming-style furniture Four-head official’s cap chair rosewood with golden flecks Wang Shixiang inscription cultural value
在线阅读 下载PDF
Research on the Symbolic Value of Nuo Masks in the Context of Contemporary Intangible Cultural Heritage Preservation
7
作者 LIU Yuan-feng HUANG Li-na LIN Hai-tao 《Journal of Literature and Art Studies》 2026年第1期67-71,共5页
The Nuo mask is the core visual vehicle within China’s Nuo culture and constitutes a complex symbolic system through facial features(icons),patterns(indexes),and colors(symbols).Within the context of intangible cultu... The Nuo mask is the core visual vehicle within China’s Nuo culture and constitutes a complex symbolic system through facial features(icons),patterns(indexes),and colors(symbols).Within the context of intangible cultural heritage(ICH)preservation,its value lies in the continuation and revitalization of its dynamic symbolic functions.Grounded in semiotic theory,this paper elaborates on three core dimensions of symbolic value manifested by Nuo masks in ICH preservation:a ritual symbol for living transmission,a symbol of identity for collective memory,and an aesthetic symbol as a source of creativity. 展开更多
关键词 Nuo masks intangible cultural heritage preservation symbolic value sense of community for the Chinese nation cultural innovation
在线阅读 下载PDF
A study on the environmental background values in the Mt. Namjagbarwa region, Tibet 被引量:1
8
作者 Huang Yanchu, Liu Quangyou, Ma Ciguang and Shan Xiaoquan Research Center for Eco-Environmetal sciences,Academia Sinica,P.O.Box 934,Beijing 100083, China. 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 1989年第1期39-45,共7页
A study on the elemental composition of aerosol, water and soil in the Mt. Namjagbarwa region, Tibet, was carried out in the period of 1982 to 1984. Samples of aerosol particles were collected by cascade impactor and ... A study on the elemental composition of aerosol, water and soil in the Mt. Namjagbarwa region, Tibet, was carried out in the period of 1982 to 1984. Samples of aerosol particles were collected by cascade impactor and analyzed for 10 elements by PIXE. Samples of ice, snow and water were collected and analyzed for trace metals, major cations and anions. The pH values of water were at quasi-neutrality or neutrality, and the hardness of water was low. Contents and physico-chemical composition of 20 elements in the major types of soil were determined by physico-chemical methods. Levels of elements in soil varied with soil type and their parent materials. Contents of some elements were higher in the substratum soil derived from in situ than in the surface soil. The region was in a remote area with negligible pollution and could be considered as a good location for measuring the baskground value of environmental sample. 展开更多
关键词 AEROSOL water SOIL background value.
在线阅读 下载PDF
Optimization approach of background value and initial item for improving prediction precision of GM(1,1) model 被引量:34
9
作者 Yuhong Wang Qin Liu +2 位作者 Jianrong Tang Wenbin Cao Xiaozhong Li 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2014年第1期77-82,共6页
A combination method of optimization of the back-ground value and optimization of the initial item is proposed. The sequences of the unbiased exponential distribution are simulated and predicted through the optimizati... A combination method of optimization of the back-ground value and optimization of the initial item is proposed. The sequences of the unbiased exponential distribution are simulated and predicted through the optimization of the background value in grey differential equations. The principle of the new information priority in the grey system theory and the rationality of the initial item in the original GM(1,1) model are ful y expressed through the improvement of the initial item in the proposed time response function. A numerical example is employed to il ustrate that the proposed method is able to simulate and predict sequences of raw data with the unbiased exponential distribution and has better simulation performance and prediction precision than the original GM(1,1) model relatively. 展开更多
关键词 background value initial item grey system theory grey prediction.
在线阅读 下载PDF
RESEARCHES ON SOIL ENVIRONMENTAL BACKGROUND VALUES IN TIBET 被引量:1
10
作者 张晓平 科扬川 《Chinese Geographical Science》 SCIE CSCD 1995年第1期56-65,共10页
The environmental background values of 13 elements of Hg, As, Se, Cr,Mn, V, Ph, Cd, Zn, Cu, Ni, F and Co in xizang soils are obtained through analyzing and determining 205 samples of surface soils in Tibet and the fin... The environmental background values of 13 elements of Hg, As, Se, Cr,Mn, V, Ph, Cd, Zn, Cu, Ni, F and Co in xizang soils are obtained through analyzing and determining 205 samples of surface soils in Tibet and the final data processing. The background val 展开更多
关键词 TIBET background valueS SOIL R- TYPE of CLUSTER analysis
在线阅读 下载PDF
Establishing environmental background values of selected trace elements and environmental quality assessment of fi negrained sediments in the Jiaozhou Bay catchment,China
11
作者 Fangjian XU Xu TIAN +2 位作者 Xianchao WANG Xiaoming WAN Bo CHEN 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2023年第4期1444-1453,共10页
With the development of economy,the impact of human activities on ecological environment is increasing,and environmental protection work is important.Trace elements(Co,Ni,Cu,Pb,Zn,Cd,Cr,and Sc)in surface fi ne-grained... With the development of economy,the impact of human activities on ecological environment is increasing,and environmental protection work is important.Trace elements(Co,Ni,Cu,Pb,Zn,Cd,Cr,and Sc)in surface fi ne-grained sediment samples from the Jiaozhou Bay catchment were selected to evaluate their 2015 environmental background values and the environmental quality.Using statistical analysis,the environmental background values(ranges)of Sc,Co,Ni,Cu,Pb,Zn,Cd,and Cr were calculated,being 13.1(10.8-15.4),12.4(8.6-16.2),32.0(22.9-41.2),29.6(13.5-64.9),24.1(13.0-44.6),77.6(38.5-156.5),0.07(0.02-0.20),and 82.5(66.5-104.0)mg/kg,respectively.The enrichment factor,contamination factor,and pollution load index were used to evaluate the pollution status of the Jiaozhou Bay catchment.The environmental background values of most elements are higher than those of the upper continental crust and lower than those of global shale.At present,the pollution in the eastern Jiaozhou Bay is much higher than that in the western part.The results shall be helpful for future management for trace element pollution monitoring in the Jiaozhou Bay catchment. 展开更多
关键词 SEDIMENTS environmental background values environmental assessment CONTAMINATION Jiaozhou Bay
在线阅读 下载PDF
Assessment and analysis of ecosystem services value along the Yangtze River under the background of the Yangtze River protection strategy 被引量:10
12
作者 ZHENG Liang LIU Hai +2 位作者 HUANG Yuefei YIN Shoujing JIN Gui 《Journal of Geographical Sciences》 SCIE CSCD 2020年第4期553-568,共16页
The Yangtze River is the third largest river in the world and the longest and largest river in China.China has adopted a national strategy to protect the Yangtze River.A better understanding of the ecosystem services ... The Yangtze River is the third largest river in the world and the longest and largest river in China.China has adopted a national strategy to protect the Yangtze River.A better understanding of the ecosystem services value along the Yangtze River would provide support for the Yangtze River protection strategy.Using Costanza’s method to estimate the ecosystem services value,the value of 10 ecosystem services was estimated within 1 km and 2 km from the Yangtze River in 2017.These 10 services were derived from the four established groupings of provisioning,regulating,supporting,and cultural services.This study compared and analyzed the changes in the ecosystem services value in the upper,middle,and lower reaches of the river,and in provinces,cities,and villages along the Yangtze River.The total ecosystem services value within 1 km and 2 km from the river was 37.208 and 43.769 billion yuan,respectively.Within 1 km,the ecosystem services value in the middle reaches was 12.93 billion yuan,while the next highest value was in the upper reaches at 12.45 billion yuan,and the downstream area had the smallest value of 11.855 billion yuan.Within 2 km,the value of upstream ecosystem services was the highest at 16.31 billion yuan,while the second highest value was in the middle reaches at 14.376 billion yuan,and the smallest value was in the downstream area at 13.083 billion yuan.In the Yangtze River Basin,regulating services played a leading role,accounting for 81.6%and 78.9%of the ecosystem services value within 1 km and 2 km from the river,respectively.Among the 10 ecosystem services,hydrological regulation was the most important,while the value of raw material production made the smallest contribution.Among the provinces and cities along the Yangtze River,the highest ecosystem services value was in Hubei Province,while the lowest values were in Shanghai and the Qinghai-Tibet Plateau.If villages within 1 km and 2 km from the river were to be relocated,the total regional ecological value would increase by 527 and 975 million yuan,respectively. 展开更多
关键词 YANGTZE RIVER Basin 1 KM ALONG the YANGTZE RIVER 2 KM ALONG the YANGTZE RIVER value ASSESSMENT method ecosystem services
原文传递
Soil Geochemical Background Value and Environmental Quality Assessment in Jinan City
13
作者 Hongjin WANG Chao YU +1 位作者 Wenkai REN Yan GUO 《Agricultural Biotechnology》 CAS 2022年第5期72-75,79,共5页
[Objectives]This study was conducted to accurately assess soil and environmental quality in Jinan City. [Methods] Based on the multipurpose regional geochemical survey data of 1∶250 000 in Shandong Province, the diff... [Objectives]This study was conducted to accurately assess soil and environmental quality in Jinan City. [Methods] Based on the multipurpose regional geochemical survey data of 1∶250 000 in Shandong Province, the differences between the soil geochemical background values of 54 indexes in Jinan City and the soil in the whole province and the comprehensive geochemical class of soil quality were studied. [Results] The contents of C and Cao in Jinan soil was significantly higher than the background values of Shandong Province. The Cd, Cr, Cu, F, Ni, Sn, MgO, Cao and Na_(2)O contents and pH value were higher than the abundance of the A soil layer in China, but the nutrient index contents of Se, I and OrgC were lower than the national background values. The surface soil quality in the study area was generally good, with the sum of superior, good and medium accounting for 99.76% of the total area of the study area. The distribution area of poor soil was the least, accounting for only 0.24%, and it was scattered near industrial and mining enterprises in the urban area of Jinan City, Laiwu District, Gangcheng District and Zhangqiu District, which was closely related to human activities. [Conclusions] This study has practical guiding significance for improving land use efficiency. 展开更多
关键词 Surface soil background value GEOCHEMISTRY Land quality Assessment Jinan city
在线阅读 下载PDF
BACKGROUND VALUES AND TREND DISTRIBUTION OF Cu, Zn AND Ni IN SOILS IN CHINA
14
作者 王景华 《Chinese Geographical Science》 SCIE CSCD 1992年第4期67-76,共10页
The background values of Cu, Zn and Ni are discussed based on the analytical data of 21 main soil types collected from various regions in China. According to statistics of many samples, the background value of Cu is 2... The background values of Cu, Zn and Ni are discussed based on the analytical data of 21 main soil types collected from various regions in China. According to statistics of many samples, the background value of Cu is 23.4±10.2 mg/ kg (482 samples), Zn 77.9±2.39 mg/ kg (474 samples), Ni 30.0±12.8 mg/kg (482 samples). 展开更多
关键词 Soil background valueS of CU ZN and NI TREND DISTRIBUTION
在线阅读 下载PDF
STUDIES ON ENVIRONMENTAL BACKGROUND VALUES IN CHINA
15
作者 缪天成 王惠琪 郑春江 《Chinese Geographical Science》 SCIE CSCD 1991年第4期16-25,共10页
An investigation on environmental background values was made in an area of about 1,140,000 km2, which included temperate and subtropical zones of China. The environmental background values of 142 soil environment unit... An investigation on environmental background values was made in an area of about 1,140,000 km2, which included temperate and subtropical zones of China. The environmental background values of 142 soil environment units, 18 main soil types, 87 surface water environment units, 8 aquatic organism environment units and 20 underground water environment units were obtained. The rules, causes and effecting factors of regional differentiation of the environmental background values were deduced from over 200,000 various data. 展开更多
关键词 SOIL water ORGANISM ENVIRONMENTAL background value
在线阅读 下载PDF
THE BACKGROUND VALUES OF RARE EARTH AND RADIOACTIVE ELEMENTS IN WATER SYSTEM OF SOURCE AREA OF THE CHANG JIANG RIVER
16
作者 张立诚 周克俊 +1 位作者 钱杏珍 李岫霞 《Chinese Geographical Science》 SCIE CSCD 1993年第3期74-85,共12页
Using neutron activation analysis method we determined contents of rare-earth and radioactive elements (La, Ce, Nd, Sm, Eu, Tb, Yb, Lu, Cs, Rb, Sb, Sc, Sr, Ba, U, Th) in source water system of the Changjiang (Yangtze)... Using neutron activation analysis method we determined contents of rare-earth and radioactive elements (La, Ce, Nd, Sm, Eu, Tb, Yb, Lu, Cs, Rb, Sb, Sc, Sr, Ba, U, Th) in source water system of the Changjiang (Yangtze) River, which is mainly composed of the Tuotuo River, the Chumaer River, and the Buqu River. The contents of these elements in the unflltered water have a great variation and a close correlation with the water turbidity. The contents of these elements in filtered water only have a little variation and are lower than those in the unflltered water. The variations in contents of these elements in sediments are also very little. These elements in the unifiltered water are in geometric distribution, except Sc. Most of the elements in sediments are in arithmetic distribution, but Cs, Sb, Th, are in deviation distribution. The contents of most of these elements in the river source area correspond to the contents of fresh water of the earth. Most of these elements have a little variation in their 展开更多
关键词 source area of the CHANGJIANG RIVER background value RADIOACTIVE elements neutron activation analysis method
在线阅读 下载PDF
Physical background on estimating bvalue
17
作者 黄玮琼 李文香 《Acta Seismologica Sinica(English Edition)》 CSCD 1997年第1期104-111,共8页
The G R relation lg N=a-bM( 1954)is an empirical formula used widely in the seismicity research. But the linearity of b curves has great difference in different time and space domains. An interested question in... The G R relation lg N=a-bM( 1954)is an empirical formula used widely in the seismicity research. But the linearity of b curves has great difference in different time and space domains. An interested question in this paper is that in how large a space time strength domain the b value has certain physical connotation. This study told us that we can get optimal statistical results of b value in those space time domains which can develop correspondent strong shocks with magnitude interval( M S≥8.5, 8.0≤ M S<8.5, 7.0≤ M S<8.0). Thus, the possible seismogenic areas in which strong shocks with different magnitude intervals develop can be inferred in different regions of the mainland of China. Finally, some new problems are proposed, such as the delimitation of seismic province, the seismicity parameter determination in seismic hazard analysis and in earthquake predictions by using b value. 展开更多
关键词 estimation of b value seismogenic area strong shocks with different magnitude interval
在线阅读 下载PDF
A Statistical Algorithm for Retrieving Background Value of Absorbing Aerosol Index Based on TROPOMI Measurements
18
作者 Fuying TANG Weihe WANG +4 位作者 Fuqi SI Haijin ZHOU Yuhan LUO Dongshang YANG Yuanyuan QIAN 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2023年第6期1104-1116,共13页
The ultraviolet aerosol index(UVAI) is essential for monitoring the absorbing aerosols during aerosol events. UVAI depends on the absorbing aerosol concentration, the viewing geometry, and the temporal drift of radiom... The ultraviolet aerosol index(UVAI) is essential for monitoring the absorbing aerosols during aerosol events. UVAI depends on the absorbing aerosol concentration, the viewing geometry, and the temporal drift of radiometric sensitivity. To efficiently detect absorbing aerosols with the highest precision and to improve the accuracy of long-term UVAI estimates,the background UVAI must be examined through the UVAI retrieval. This study presents a statistical method that calculates the background value of UVAI using TROPOspheric Monitoring Instrument(TROPOMI) observation data over the Pacific Ocean under clear-sky scenes. Radiative transfer calculations were performed to simulate the dependence of UVAI on aerosol type and viewing geometry. We firstly applied the background UVAI to reducing the effects of viewing geometry and the degradation of the TROPOMI irradiance measurements on the UVAI. The temporal variability of the background UVAI under the same viewing geometry and aerosol concentration was identified. Radiative transfer calculations were performed to study the changes in background UVAI using Aerosol Optical Depth from the Moderate Resolution Imaging Spectroradiometer(MODIS) and reflectance measurements from TROPOMI as input. The trends of the temporal variations in the background UVAI agreed with the simulations. Alterations in the background UVAI expressed the reflectance variations driven by the changes in satellite state. Decreasing trends in solar irradiance at 340 and 380 nm due to instrument degradation were identified. Our findings are valuable because they can be applied to future retrievals of UVAI from the Environmental Trace Gases Monitoring Instrument(EMI) onboard the Chinese GaoFen-5 satellite. 展开更多
关键词 ultraviolet aerosol index background UVAI TROPOMI reflectance DEGRADATION
在线阅读 下载PDF
Chromium transformation driven by iron redox cycling in basalt-derived paddy soil with high geological background values
19
作者 Ke Zhang Yang Yang +5 位作者 Wenting Chi Guojun Chen Yanhong Du Shiwen Hu Fangbai Li Tongxu Liu 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2023年第3期470-479,共10页
The flooding and drainage of paddy fields has great effects on the transformation of heavy metals, however, the transformation of Cr in basalt-derived paddy soil with high geological background values was less recogni... The flooding and drainage of paddy fields has great effects on the transformation of heavy metals, however, the transformation of Cr in basalt-derived paddy soil with high geological background values was less recognized. The typical basalt-derived paddy soil was incubated under alternating redox conditions. The Cr fractions and the dynamics of Fe/N/S/C were examined. The HCl-extractable Cr increased under anaerobic condition and then decreased during aerobic stage. The UV-vis spectra of the supernatant showed that amounts of colloids were released under anaerobic condition, and then re-aggregated during aerobic phase. The scanning transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy(XPS) revealed that Fe oxides were reduced and became dispersed during anaerobic stage, whereas Fe(Ⅱ) was oxidized and recrystallized under aerobic condition. Based on these results, a kinetic model was established to further distinguish the relationship between the transformation of Cr and Fe. During anaerobic phase, the reduction of Fe(Ⅲ) oxides not only directly released the structurally bound Cr, but also enhanced the breakdown of soil aggregation and dissolution of organic matter causing indirect mobilization of Cr. During aerobic phase, the oxidation of Fe (Ⅱ) and further recrystallization of newly formed Fe(Ⅲ) oxides might induce the re-aggregation of soil colloids and further incorporation of Cr. In addition,the kinetic model of Cr and Fe transformation was further verified in the pot experiment.The model-based findings demonstrated that the Cr transformation in the basalt-derived paddy soil with high geological background values was highly driven by redox sensitive iron cycling. 展开更多
关键词 CHROMIUM Paddy soil Iron oxides Redox High geological background
原文传递
Study on Value Chain of Telecom VAS under Transformation Background
20
作者 Yanming TAN Jianqiu ZENG 《Communications and Network》 2009年第2期63-67,共5页
Driven by both technology and market, telecom industry is becoming a part of several converged industries in information society gradually from an independent industry which provides telecom products like voice or dat... Driven by both technology and market, telecom industry is becoming a part of several converged industries in information society gradually from an independent industry which provides telecom products like voice or data. Under such background, this paper introduces a new value chain model of telecom value-added ser-vices in the new environment, providing theoretic support for transformation of telecom operators. 展开更多
关键词 TELECOM TRANSFORMATION TELECOM VAS value CHAIN SERVICE-ORIENTED
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