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A 48-bp deletion upstream of LIGULELESS 1 alters rice panicle architecture
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作者 Linhua Wu Min Hu +6 位作者 Shuwei Lyu Wenfeng Chen Hang Yu Qing Liu Wei He Chen Li Zuofeng Zhu 《The Crop Journal》 SCIE CSCD 2024年第2期354-363,共10页
Panicle architecture is an agronomic determinant of crop yield and a target for cereal crop improvement.To investigate its molecular mechanisms in rice,we performed map-based cloning and characterization of OPEN PANIC... Panicle architecture is an agronomic determinant of crop yield and a target for cereal crop improvement.To investigate its molecular mechanisms in rice,we performed map-based cloning and characterization of OPEN PANICLE 1(OP1),a gain-of-function allele of LIGULELESS 1(LG1),controlling the spread-panicle phenotype.This allele results from a 48-bp deletion in the LG1 upstream region and promotes pulvinus development at the base of the primary branch.Increased OP1 expression and altered panicle phenotype in chimeric transgenic plants and upstream-region knockout mutants indicated that the deletion regulates spread-panicle architecture in the mutant spread panicle 1(sp1).Knocking out BRASSINOSTEROID UPREGULATED1(BU1)gene in the background of OP1 complementary plants resulted in compact panicles,suggesting OP1 may regulate inflorescence architecture via the brassinosteroid signaling pathway.We regard that manipulating the upstream regulatory region of OP1 or genes involved in BR signal pathway could be an efficient way to improve rice inflorescence architecture. 展开更多
关键词 upstream region Panicle architecture Gene expression BR Rice
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Influence of upstream solar wind on magnetic field distribution in the Martian nightside ionosphere
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作者 JiaWei Gao ZhaoJin Rong +3 位作者 Qi Zhang Anna Mittelholz Chi Zhang Yong Wei 《Earth and Planetary Physics》 EI CAS CSCD 2024年第5期728-741,共14页
Using over eight years of Mars Atmosphere and Volatile Evolutio N(MAVEN)data,from November 2014 to May 2023,we have investigated the Martian nightside ionospheric magnetic field distribution under the influence of ups... Using over eight years of Mars Atmosphere and Volatile Evolutio N(MAVEN)data,from November 2014 to May 2023,we have investigated the Martian nightside ionospheric magnetic field distribution under the influence of upstream solar wind drivers,including the interplanetary magnetic field intensity(∣BIMF∣),solar wind dynamic pressure(PS W),solar extreme ultraviolet flux(EUV),and Martian seasons(L s).Our analysis reveals pronounced correlations between magnetic field residuals and both∣BIMF∣and PS W.Correlations observed with EUV flux and Ls were weaker—notably,magnetic field residuals increased during periods of high EUV flux and at Mars perihelion.We find that the IMF penetrates to an altitude of 200 km under a wide range of upstream conditions,penetrating notably deeper under high∣BIMF∣andPSWconditions.Our analysis also indicates that EUV flux and IMF cone angle have minimal impact on IMF penetration depth.Those findings provide useful constraints on the dynamic nature of Martian atmospheric escape processes and their evolution,suggesting that historical solar wind conditions may have facilitated deeper IMF penetration and higher rates of ionospheric escape than are observed now.Moreover,by establishing criteria for magnetic‘quiet’conditions,this study offers new insights into the planet’s magnetic environment under varying solar wind influences,knowledge that should help refine models of the Martian crustal magnetic field. 展开更多
关键词 Martian magnetic field external magnetic field upstream solar wind drivers IMF penetration altitude magnetic field activity indices
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Variation Characteristics of Main Climate Factors in the Upstream of Wei River in Recent 39 Years 被引量:5
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作者 姚小英 蒲金涌 刘晓强 《Meteorological and Environmental Research》 CAS 2010年第9期9-11,共3页
Wei River is an important river which affects the industrial and agricultural production,people's life in Guanzhong district of Shaanxi and the east of Gansu.To study the variation characteristics of main climate ... Wei River is an important river which affects the industrial and agricultural production,people's life in Guanzhong district of Shaanxi and the east of Gansu.To study the variation characteristics of main climate factors in recent 39 years in the upstream of Wei River,we analyzed the variation characteristics of climate factors by using the data in 11 meteorological stations in the upstream basin of Wei River during 1971-2009.The results showed that the precipitation presented the decline trend in the basin,and the temperature rose in 0.3 ℃/10 a trend.The temperature increase trend was 0.4 ℃/10 a in winter,spring and wasn't obvious in summer,autumn.The potential evapotranspiration presented the yearly increase trend in recent years.The precipitation decreased,and the temperature rose.Moreover,the potential evapotranspiration strengthened.It wasn't favorable for the healthy run of ecological system in the upstream,downstream basins and aggravated the shortage degree of water resources. 展开更多
关键词 Wei River upstream Climate factor Variation CHARACTERISTIC China
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Torrent risk zonation in the Upstream Red River Basin based on GIS 被引量:5
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作者 TANG Chuan ZHU Jing 《Journal of Geographical Sciences》 SCIE CSCD 2006年第4期479-486,共8页
This paper explores the methodology for compiling the torrent hazard and risk zonation map by means of GIS technique for the Red River Basin in Yunnan province of China, where is prone to torrent. Based on a 1:250,00... This paper explores the methodology for compiling the torrent hazard and risk zonation map by means of GIS technique for the Red River Basin in Yunnan province of China, where is prone to torrent. Based on a 1:250,000 scale digital map, six factors including slope angle, rainstorm days, buffer of river channels, maximum runoff discharge of standard area, debris flow distribution density and flood disaster history were analyzed and superimposed to create the torrent risk evaluation map. Population density, farmland percentage, house property, and GDP as indexes accounting for torrent hazards were analyzed in terms of vulnerability mapping. Torrent risk zonation by means of GIS was overlaid on the two data layers of hazard and vulnerability. Then each grid unit with a resolution of 500 m- 500 m was divided into four categories of the risk: extremely high, high, moderate and low. Finally the same level risk was combined into a confirmed zone, which represents torrent risk of the study area. The risk evaluation result in the upper Red River Basin shows that the extremely high risk area of 13,150 km^2 takes up 17.9% of the total inundated area, the high risk area of 33,783 km^2 is 45.9%, the moderate risk area of 18,563 km^2 is 25.2% and the low risk area of 8115 km^2 is 11.0%. 展开更多
关键词 torrent risk zonation GIS the upstream Red River Basin
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Application of an Explicit Upstream FEM in Estuary Study 被引量:2
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作者 耿兆铨 倪勇强 +1 位作者 潘存鸿 朱军政 《China Ocean Engineering》 SCIE EI 1999年第3期343-352,共10页
The Explicit Upstream FEM (EU-FEM) proposed in this paper not only possesses the advantages of saving memory and CPU time for FDM, but also fits boundary easily, arranges nodal points flexibly and makes local grids fi... The Explicit Upstream FEM (EU-FEM) proposed in this paper not only possesses the advantages of saving memory and CPU time for FDM, but also fits boundary easily, arranges nodal points flexibly and makes local grids fine down conveniently. The software package, which consists of EU-FEM models and pre/post-processing skills, has been widely used to estuary, near-shore, bay, lake and complex waters with many islands and channels. In addition to flow field, this model can be used to calculate the distribution fields of pollutants, temperature, salinity, sediment, and oil spill, and can be used to case study of estuary regulation projects. Some practical applications are presented and some problems discussed. 展开更多
关键词 Explicit upstream FEM ESTUARY numerical simulation PREPROCESSING POST-PROCESSING
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Analysis and forecasts of investment scale and structure in upstream sector for oil companies based on system dynamics 被引量:2
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作者 Zhang Baosheng Wang Qing 《Petroleum Science》 SCIE CAS CSCD 2011年第1期120-126,共7页
Oil and gas exploration and production is the most important and key segment in the whole business chain of the petroleum industry.Therefore,oil companies always put much emphasis on making scientific and reasonable d... Oil and gas exploration and production is the most important and key segment in the whole business chain of the petroleum industry.Therefore,oil companies always put much emphasis on making scientific and reasonable decisions about investment scale and structure in the upstream sector,so that they can minimise business risks and obtain high returns.According to the system dynamics theories and methods and based on the actual results from an oil company's practice in China,a system dynamics model is built in this paper for analyzing and forecasting the upstream investment scale and structure for an oil company.This model was used to analyze the investment effect of a large oil company in China, and the results showed that the total upstream investment scale will decline slowly in a short period and the investment proportion of different parts should be adjusted if some influencing factors are taken into account.This application practice was compared with the actual data and indicated that the system dynamics(SD) model presented in this paper is a useful tool for analyzing and forecasting of upstream investment scale and structure of oil companies in their investment decisions. 展开更多
关键词 Oil companies upstream investment scale and structure analysis and forecast system dynamics
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Institutional preparation for relaxation of control over the upstream petroleum industry in China 被引量:2
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作者 Chen Shouhai Zhang Baosheng 《Petroleum Science》 SCIE CAS CSCD 2009年第1期98-103,共6页
Relaxation of control over the upstream business of the petroleum industry in China is discussed. The authors suggest that a basic institutional preparation should be made before relaxing control over the upstream bus... Relaxation of control over the upstream business of the petroleum industry in China is discussed. The authors suggest that a basic institutional preparation should be made before relaxing control over the upstream business, and that the institutional preparation includes at least four parts: 1) setting up the admission standards, 2) perfecting the management system of mining rights, 3) reforming the royalty and taxation system for oil and gas resources, and 4) improving the supervision and management system. Stressing the institutional preparation before relaxation of control does not mean that China could not relax control over the upstream business until the management systems are perfected, but the authors suggest that China could establish a necessary system for relaxation of control and to improve it with future practice. 展开更多
关键词 Petroleum industry upstream business relaxation of control institutional preparation
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Study of temperature and precipitation change in upstream mountain area of the Hexi inland river basin since 1960s 被引量:4
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作者 YongChao Lan HongLang Xiao +4 位作者 XingLin Hu HongWei Ding SongBing Zou ChengFang La Jie Song 《Research in Cold and Arid Regions》 2012年第6期522-535,共14页
All rivers in the Hexi inland region of Gansu Province, China, originate from the northern slope of the Qilian Mountains. They are located in the southern portion of the region and respectively belong to the three lar... All rivers in the Hexi inland region of Gansu Province, China, originate from the northern slope of the Qilian Mountains. They are located in the southern portion of the region and respectively belong to the three large river systems from east to west, the Shiyang, Heihe and Shule river basins. These rivers are supplied by precipitation, snowmelt and ice-melt runoff from the Qilian Mountain area. Therefore, changes of precipitation and temperature in the upstream watersheds of these rivers have an important effect on changes of mountainous runoff and reasonable utilization of water resources in this region. For this reason, the Qilian Mountain area, upstream watersheds and runoff forming areas of these rivers are chosen as the study area. The change characteristics and variation trend of temperature and precipitation in this area under the backdrop of global warming axe analyzed based on observa- tional data of relational weather and hydrologic stations in the area. Results show that temperatures in the upriver mountain areas of these three large river basins have been increasing, although the increasing degree is differentially affected by global warming. The rising extent of annual and seasonal temperatures in the upstream mountain area of the Shule river basin located in the west- em Qilian Mountains, were all largest over the past 50 years. Precipitation in the upstream mountain areas of Hexi region' three river basins located respectively in the western, middle and eastern Qilian Mountains have been presenting an increasing trend to varying degrees as a whole for more than 50 years. This means that climate in the upstream mountain areas of Hexi region' three river basins are becoming increasingly warmer and moister over the past 50 years, which will be very good for the ecological en- vironment and agricultural production in the region. 展开更多
关键词 global warming upstream mountain area Qilian Mountains three large fiver systems Hexi inland fiver basin
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Aspects of the upstream region in a plasma jet with dielectric barrier discharge configurations 被引量:2
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作者 李雪辰 贾鹏英 +1 位作者 袁宁 常媛媛 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第4期413-418,共6页
A plasma column with a length of about 65 cm is generated in the upstream region of a plasma jet using dielectric barrier discharge configurations. The effects of experimental parameters such as the amplitude of the a... A plasma column with a length of about 65 cm is generated in the upstream region of a plasma jet using dielectric barrier discharge configurations. The effects of experimental parameters such as the amplitude of the applied voltage and the driving frequency are investigated in aspects of the plasma column by the optical method. Results show that both the plasma length and the propagating velocity, as well as the discharge current, increase with the increase in the applied voltage or its frequency. The discharge mechanism is analysed qualitatively based on streamer theory, where photo-ionization is important. Furthermore, optical emission spectroscopy is used to investigate the electric field intensity of the upstream region. 展开更多
关键词 dielectric barrier discharge plasma jet upstream region optical emission spectroscopy
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Impacts of water and soil erosion in upstream watershed of Nenjiang River 被引量:2
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作者 ZHU Dandan MA Yongsheng SHI Qiuyue 《Journal of Northeast Agricultural University(English Edition)》 CAS 2007年第3期283-288,共6页
Making a brief analysis of the water and soil loss present situation in Daxing'anling area which locates to the upstream region of Nenjiang River, and giving the water and soil loss of this area that have been made n... Making a brief analysis of the water and soil loss present situation in Daxing'anling area which locates to the upstream region of Nenjiang River, and giving the water and soil loss of this area that have been made near 20 years, as well as the factors of the water and soil loss. According to the factors corresponding prevention measure and forecast model have been put forward, make a brief introduction to this model in this article. It is helpful to improve the local soil conservation and sustainable development. 展开更多
关键词 upstream region of Nenjiang River water and soil loss water and soil conservation PREDICTION
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Upstream Operations in the Oil Industry: Rigorous Modeling ofan Electrostatic Coalescer 被引量:1
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作者 Francesco Rossi Simone Colombo +2 位作者 Sauro Pierucci Eliseo Ranzi Flavio Manenti 《Engineering》 SCIE EI 2017年第2期220-231,共12页
This paper deals with a first-principle mathematical model that describes the electrostatic coalescer unitsdevoted to the separation of water from oil in water-in-oil emulsions, which are typical of the upstreamoperat... This paper deals with a first-principle mathematical model that describes the electrostatic coalescer unitsdevoted to the separation of water from oil in water-in-oil emulsions, which are typical of the upstreamoperations in oil fields. The main phenomena governing the behavior of the electrostatic coalescer are denscribed, starting from fundamental laws. In addition, the gradual coalescence of the emulsion droplets isconsidered in the mathematical modeling in a dynamic fashion, as the phenomenon is identified as a keystep in the overall yield of the unit operation. The resulting differential system with boundary conditionsis then integrated via performing numerical libraries, and the simulation results confirm the available lit-erature and the industrial data. A sensitivity analysis is provided with respect to the main parameters. Themathematical model results in a flexible tool that is useful for the purposes of design, unit behavior predic-tion. performance rnoniroring, and ontimization. 展开更多
关键词 upstream operations ELECTROSTATIC COALESCER Desalter Rigorous modeling Water-oil EMULSION
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Functional characterization of a Δ6 fatty acid desaturase gene and its 5′-upstream region cloned from the arachidonic acid-rich microalga Myrmecia incisa Reisigl(Chlorophyta) 被引量:1
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作者 ZHANG Li CAO Haisheng +1 位作者 NING Pu ZHOU Zhigang 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2018年第6期2308-2321,共14页
It is suggested that Δ6 fatty acid desaturase(FAD) plays a critical role in the biosynthesis of polyunsaturated fatty acids in plants and microalgae. But why does it adapt to the changed environments such as nitrogen... It is suggested that Δ6 fatty acid desaturase(FAD) plays a critical role in the biosynthesis of polyunsaturated fatty acids in plants and microalgae. But why does it adapt to the changed environments such as nitrogen starvation is seldom understood. One Δ6 FAD gene( MiD6 fad) from an arachidonic acidrich microalga M yrmecia incisa Reisigl(Chlorophyta) was first heterologously expressed in S accharomyces cerevisiae for the identification of function. The fatty acid profile of transgenic yeast detected by gas chromatography-mass spectrometry illustrated that the enzyme MiD6 FAD could convert linoleic and ?-linolenic acids to γ-linolenic and stearidonic acids, respectively, demonstrating that M iD6 fad encoded a Δ6 FAD. A 1 965-bp fragment of the cloned 2 347-bp 5′-upstream region of M iD6 fad was next subcloned and fused upstream with green fluorescent protein(GFP) gene to replace the GAL1 promoter of the vector pYES2. The generated construct was transformed into S. cerevisiae for function determination. Confocal microscopic images of the transformed line illustrated that this inserted fragment could drive GFP expression, which was further verified by fluorescence intensity quantification and Western blot analysis using antiGFP antibody. The conversion efficiency(approximately 2%-3%) of MiD6 FAD was much lower than the reported ? 3 FAD and Δ6 elongase in this microalga, suggesting that MiD6 FAD catalysed the possible ratelimiting step for ArA biosynthesis. The presence of several putative c is-acting regulatory elements in this identified promoter sheds new light on the regulation mechanism research of Δ6 FAD transcription for the ArA production in M. incisa in changing environmental factors. 展开更多
关键词 arachidonic acid(ArA) fatty ACID desaturase(FAD) green fl uorescent protein(GFP) green MICROALGA Saccharomyces cerevisiae 5′-upstream region(5′-USR)
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PbEIL1 acts upstream of PbCysp1 to regulate ovule senescence in seedless pear 被引量:4
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作者 Huibin Wang Haiqi Zhang +8 位作者 Fangfang Liang Liu Cong Linyan Song Xieyu Li Rui Zhai Chengquan Yang Zhigang Wang Fengwang Ma Lingfei Xu 《Horticulture Research》 SCIE 2021年第1期818-829,共12页
Numerous environmental and endogenous signals control the highly orchestrated and intricate process of plant senescence.Ethylene,a well-known inducer of senescence,has long been considered a key endogenous regulator o... Numerous environmental and endogenous signals control the highly orchestrated and intricate process of plant senescence.Ethylene,a well-known inducer of senescence,has long been considered a key endogenous regulator of leaf and flower senescence,but the molecular mechanism of ethylene-induced ovule senescence has not yet been elucidated.In this study,we found that blockage of fertilization caused ovule abortion in the pear cultivar‘1913’.According to transcriptome and phytohormone content data,ethylene biosynthesis was activated by pollination.At the same time,ethylene overaccumulated in ovules,where cells were sensitive to ethylene signals in the absence of fertilization.We identified a transcription factor in the ethylene signal response,ethylene-insensitive 3-like(EIL1),as a likely participant in ovule senescence.Overexpression of PbEIL1 in tomato caused precocious onset of ovule senescence.We further found that EIL1 could directly bind to the promoter of the SENESCENCE-ASSOCIATED CYSTEINE PROTEINASE 1(PbCysp1)gene and act upstream of senescence.Yeast one-hybrid and dual-luciferase assays revealed the interaction of the transcription factor and the promoter DNA sequence and demonstrated that PbEIL1 enhanced the action of PbCysp1.Collectively,our results provide new insights into how ethylene promotes the progression of unfertilized ovule senescence. 展开更多
关键词 endogenous SENESCENCE upstream
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A study on zooplankton distribution patterns and indicator species in Kuroshio upstream area and adjacent East China Sea 被引量:4
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作者 He Dehua, Wang Chunsheng, Liu Hongbin and Yang Guanming( Received July 9, 1990 accepted November 12, 1990) 《Acta Oceanologica Sinica》 SCIE CAS CSCD 1992年第2期237-254,共18页
On the basis of the data of zooplankton biomass and three major taxa—— Copepoda, Chaetognatha andSiphonophora of May-June 1986, July-August and December 1987, the distributional patterns and the indicator species of... On the basis of the data of zooplankton biomass and three major taxa—— Copepoda, Chaetognatha andSiphonophora of May-June 1986, July-August and December 1987, the distributional patterns and the indicator species of zooplankton in the Kuroshio and adjacent waters of the East China Sea are preliminarily studied. The results are as follows:The horizontal distribution of zooplankton biomass and the abundance of copepods, chaetognaths and siphonophores arecurred in the continent area northwest of Taiwan and the south-centre section of the East China Sea continent, which are the mix front of different waters. Zooplankton in the water area inside of Ryukyu Islands presented low abundance and high diversity. There are clear seasonal variations in zooplankton biomass and abundance in the study area. The strength or weakness of different water masses and fronts is the basic reason for the variations of zooplankton biomass and abundance.The species composition of zooplankton in the study area is complex and varies, however, the tropic oceanic species predominates overwhelmingly. The distribution of different ecotype species evidences the distribution of different water masses and the state of mixture. The indicator species of each water mass are listed in the paper so as to provide grounds for the variation of currents in the Kuroshio area.The temperature and salinity of sea water are important factors affecting zooplankton distribution, composition and diversity , however the role of salinity is major. With the replacement of one season by another, the correlative levels of temperature and salinity to various zooplankton taxa are more or less significant. 展开更多
关键词 A study on zooplankton distribution patterns and indicator species in Kuroshio upstream area and adjacent East China Sea area
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THE DRIVING FORCES OF LAND USE/COVER CHANGE INTHE UPSTREAM AREA OF THE NENJIANG RIVER
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作者 YE Bao-ying1, HUANG Fang2 , ZHANG Shu-wen1, ZHANG Yang-zhen1( 1. Changchun Institute of Geography, the Chinese Academy of Sciences, Changchun 130021, P. R. China 2. College of Urban and Environmental Sciences, Northeast Normal Univers 《Chinese Geographical Science》 SCIE CSCD 2001年第4期91-95,共5页
ABSTRACT: Based on the Landsat 5 and Landsat 7 TM images, the land use/cover change was detected in the upstream area of the Nenjiang River between 1995 and 2000. With the spatial analysis techniques of GIS, the maps ... ABSTRACT: Based on the Landsat 5 and Landsat 7 TM images, the land use/cover change was detected in the upstream area of the Nenjiang River between 1995 and 2000. With the spatial analysis techniques of GIS, the maps of land use degree and its change within this period were produced. To identify the causes of changes, elevation and slope were regarded as the main natural influencing factors and were transformed from coverage format to grid format within GIS. The Thiesson polygon method was used to the spatial allocation of socio-economic factors including human population, livestock numbers, mechanizing power of farming and the nearest distance from the changed pixel to the trunk stream and to main settlements, thereby the spatial relationship between land use degree change and socio-economic factor variation was analyzed. According to results of the spatial correlation, the determinants of changes in land use/cover, i. e. elevation, slope, population density change, livestock increase were extracted quantitatively in this area. At last, the spatial multi-linear regression model of land use degree change was developed as follows: △ La = 11. 037-4. 512 * eleva-tion-0. 298 * slope + 0. 292 *△ population + 2. 596 *△ livestock. 展开更多
关键词 KEYWORDS: the upstream area of the Nenjiang RIVER LAND use DEGREE change Thiesson POLYGON method drivingforces
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Upstream-downstream cooperation approach in Guanting Reservoir watershed
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作者 YANGZhi-feng ZHANGWen-guo 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2005年第4期676-680,共5页
A case study is introduced and discussed concerning water dispute of misuse and pollution between up\| and down\|stream parts. The relations between water usage and local industrial structures are analyzed. Results sh... A case study is introduced and discussed concerning water dispute of misuse and pollution between up\| and down\|stream parts. The relations between water usage and local industrial structures are analyzed. Results show it is important to change industrial structures of the target region along with controlling water pollution by technical and engineering methods. Three manners of upstream-downstream cooperation are presented and discussed based on the actual conditions of Guangting Reservoir watershed. Two typical scenarios are supposed and studied along with the local plan on water resources development. The best solution for this cooperation presents a good way to help the upstream developing in a new pattern of eco-economy. 展开更多
关键词 WATERSHED COOPERATION upstream-downstream industrial structures Guanting Reservoir
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A Review of Density Holes Upstream of Earth's Bow Shock
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作者 G K Parks E Lee +3 位作者 N Lin J B Cao S Y Fu J K Shi 《空间科学学报》 CAS CSCD 北大核心 2011年第6期693-704,共12页
Larmor size transient structures with density depletions as large as 99%of ambient solar wind density levels occur commonly upstream of Earth’s collisionless bow shock.These "density holes" have a mean dura... Larmor size transient structures with density depletions as large as 99%of ambient solar wind density levels occur commonly upstream of Earth’s collisionless bow shock.These "density holes" have a mean duration of 17.9±10.4s but holes as short as 4 s have been observed.The average fractional density depletion(δn/n) inside the holes is 0.68±0.14.The density of the upstream edge moving in the sunward direction can be enhanced by five or more times the solar wind density. Particle distributions show the steepened edge can behave like a shock,and measured local field geometries and Mach number support this view.Similarly shaped magnetic holes accompany the density holes indicating strong coupling between fields and particles.Current densities as large as 150nA·m-2 are observed at the leading compressed edge.The waves are elliptically polarized and rotating in the sense of ions(left hand) in the plasma frame.The waves appear to grow and steepen as the density holes convect with the solar wind toward the Earth.The transient nature of density holes suggests that the temporal features could represent the different stages of nonlinear evolutionary processes that produce a shock-like structure.The density holes are only observed with upstream particles,suggesting that back-streaming particles interacting with the solar wind are important. The significance of these observations is still being investigated. 展开更多
关键词 大密度 上游 地球 激波 审查 平均时间 几何形状 大电流密度
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Bacterial Community Structure of Sediment in Upstream Ecological Wetland of Guanting Reservoir under the Action of Different Plants in Winter
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作者 Yan Donghua Jiang Tiantian +4 位作者 Li Hongbo Zhai Xuezheng Wang Mengyao Wang Jianghua Zhao Jianguo 《Meteorological and Environmental Research》 CAS 2019年第1期46-48,51,共4页
In order to study the effect of reed and cattail on the bacterial community structure of surface sediments of wetland in winter,highthroughput sequencing technology was used to analyze the bacterial composition. The r... In order to study the effect of reed and cattail on the bacterial community structure of surface sediments of wetland in winter,highthroughput sequencing technology was used to analyze the bacterial composition. The results showed that 134 228 high-quality gene sequences were obtained by high-throughput sequencing in sediments of natural wetland in winter,and there were 13 866 OTUs,in which the number of OUT in sediments of reed wetland and cattail wetland was 6 677 and 7 189 respectively. The richness and diversity of bacterial communities in sediments of cattail wetland in winter were higher than those in sediments of reed wetland. Relative abundance of Proteobacteria in sediments of reed wetland and cattail wetland was 0. 54 and 0. 52,respectively. The dominant classes of bacteria were Betaproteobacteria,Deltaproteobacteria,Gammaproteobacteria and Epsilonproteobacteria,which belonged to gram-negative bacteria,indicating that the rhizosphere of wetland was easier to enrich gram-negative bacteria. Under the genus level,the dominant bacteria in the sediments were not obvious. 展开更多
关键词 HIGH-THROUGHPUT SEQUENCING Bacterial community SEDIMENT WINTER upstream ecological WETLAND of Guanting Reservoir
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Upstream-Downstream Relationships in Terms of Annual Streamflow Discharges and Drought Events in Nebraska
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作者 Hong WU Leen Kiat SOH +3 位作者 Ashok SAMAL Tao HONG David MARX Xunhong CHEN 《Journal of Water Resource and Protection》 2009年第5期299-315,共17页
Upstream-downstream relationships of annual streamflow discharges and severity and frequency of stream-flow drought events are critical in understanding how streamflow droughts propagate over time and space. Such info... Upstream-downstream relationships of annual streamflow discharges and severity and frequency of stream-flow drought events are critical in understanding how streamflow droughts propagate over time and space. Such information can be used to resolve water disputes, trigger mitigation strategies, and understand how streamflow changes due to changes in the environment. During drought years, such information is even more critical as water resources are contested. The objective of this research is to study the upstream-downstream relationships of streamflow in Nebraska along four major river systems with diverse hydrologic characteris-tics and human activities: North Platte, Big Blue, Republican, and Niobrara. The relationships among the upstream and downstream stations along the four rivers are investigated by comparing several statistics de-rived from the annual flow discharge and on drought events. Trend analysis and coefficient of variation are applied to annual flow discharge values, and a host of drought-related parameters (e.g., annual maximum drought duration, annual accumulated drought duration, number of drought events) are also computed with respect to five different levels of streamflow drought events: water shortage, mild drought, moderate drought, significant drought, and extreme drought. The paired-t test and ANOVA with MIXED procedure are subse-quently applied to the statistics to observe whether there is a significant difference between upstream and downstream stations along a river. The analysis allows us to characterize the upstream-downstream relation-ships of the four river systems, laying the groundwork for further investigations to identify the reasons for some of the trends and observations. These findings will be essential in water resources management during or prior to hydrological droughts. 展开更多
关键词 Streamflow DROUGHT upstream-Downstream Relationship Paired T-TEST Repeated Measures ANOVA with MIXED Procedure NEBRASKA
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数字化转型、创新发展与制造业价值链高质量发展 被引量:7
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作者 齐平 宋威辉 《广东财经大学学报》 CSSCI 北大核心 2024年第1期4-18,共15页
创新驱动发展战略背景下,企业数字化转型对制造业价值链高质量发展具有重要意义。采用2007—2021年沪深A股制造业上市企业数据,从价值链上游度即“强链”和价值链长度即“延链”双重视角,探析企业数字化转型对制造业价值链高质量发展的... 创新驱动发展战略背景下,企业数字化转型对制造业价值链高质量发展具有重要意义。采用2007—2021年沪深A股制造业上市企业数据,从价值链上游度即“强链”和价值链长度即“延链”双重视角,探析企业数字化转型对制造业价值链高质量发展的影响效果、作用机制与异质性特征。研究结果表明:企业数字化转型从“强链”和“延链”两方面推动了制造业价值链高质量发展,且该结论通过了稳健性检验。作用机制检验表明,企业创新发展在此过程中具有显著的正向传导作用。异质性分析表明,在非国有制企业、技术密集型行业、劳动密集型行业和创新引领型城市,企业数字化转型通过“强链”和“延链”推动制造业价值链高质量发展的效果更为显著。为此,在城市层面应健全数字化转型治理体系,在行业层面应加快“新基建”建设进程,促进数字化均衡发展,在企业层面应鼓励以强带弱、协同发展,为企业数字化转型提速增质。 展开更多
关键词 数字化转型 制造业价值链 高质量发展 创新发展 价值链上游度(“强链”) 价值链长度(“延链”)
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