期刊文献+
共找到31篇文章
< 1 2 >
每页显示 20 50 100
Production Efficiency of Four Main Crops in the Decade in Hunan Province
1
作者 邓文 刘英 +3 位作者 祝琪雅 朱雅玲 王剑 何彩莲 《Agricultural Science & Technology》 CAS 2016年第2期460-466,共7页
The research explored productive efficiencies of main crops in the decade in Hunan by nonparametric DEA method and the results showed that net output value and net-profit rate of potato and sweet potato were extremely... The research explored productive efficiencies of main crops in the decade in Hunan by nonparametric DEA method and the results showed that net output value and net-profit rate of potato and sweet potato were extremely higher than those of rice and maize, and comprehensive efficiencies from high to low were potato, rice, sweet potato and maize. It is recommended that scales of rice, maize, and sweet potato should be reduced to certain extent and the scale of potato pro- duction extended. Besides, direct fee and labor cost should be lowered as much as possible to improve net-profit rate, accelerate crop S&T development and improve grain productive efficiency. 展开更多
关键词 CROPS Productive efficiency HUNAN
下载PDF
The Effect of Nitrogen Gas Cooling Which Is Used in Aluminium Extrusion Mold on Production Efficiency 被引量:1
2
作者 Merve Ozcan Cemal Ozsut +1 位作者 Oguzhan Deveci Gulbahar Bentesen 《Open Journal of Applied Sciences》 2021年第4期414-421,共8页
It is aimed to investigate the efficiency of nitrogen gas cooling which is used in aluminium extrusion mold in this study. The exit temperature of extrusion profile increases depending on heat generated by friction an... It is aimed to investigate the efficiency of nitrogen gas cooling which is used in aluminium extrusion mold in this study. The exit temperature of extrusion profile increases depending on heat generated by friction and forming. This situation can cause to surface defects such as hot cracks and grain thickening after extrusion process. Cooling of the mold has a critical role in terms of dissipating heat close to the forming zone. Local internal cooling experiments were performed in the hot aluminium extrusion mold within the scope of this study. It has been obtained that exit temperature of the aluminium extrusion profile can be significantly reduced in experimental results. Also it was found that the reduction of press time (s) and increase of press speed (mm/s). This paper focuses the effect of nitrogen gas cooling on extrusion mold for process efficiency. The extrusion parameters were performed for comparative analysis. Its obtained that process ensures efficiency. 展开更多
关键词 Aluminium Extrusion Mold Cooling System production efficiency
下载PDF
Measurement of Grain Production Efficiency in Main Grain-producing Areas and Analysis of Inter-provincial Differences--A Study Based on Super-SBM Model and Malmquist Index
3
作者 Qi Heng Su Jing-yan 《Journal of Northeast Agricultural University(English Edition)》 CAS 2022年第2期86-96,共11页
China's food security mainly depends on the core areas of food production.Under the dual constraints of resource scarcity and environmental degradation,improving the grain production efficiency of the main grain-p... China's food security mainly depends on the core areas of food production.Under the dual constraints of resource scarcity and environmental degradation,improving the grain production efficiency of the main grain-producing areas has become the fundamental way to strengthen the grain production capacity and improve the national food security capability,and to improve the efficiency of grain production in major grain-producing areas requires empirical support.This paper used the Super SBM model and the Malmquist index to measure the grain production efficiency of the main grain-producing areas from 2001 to 2020 from both static and dynamic perspectives,and compared the differences in grain production efficiency among different soil types and different provinces(autonomous regions)in the main grain-producing areas.The results showed that from 2001 to 2020,the grain production in the main grain-producing areas was in a relatively ineffective state,and the differences in grain production efficiency among different soil types and different provinces(autonomous regions)in the main grain-producing areas were obvious.The order of grain production efficiency in different soil types was black soil region>red-yellow soil region>paddy soil region>fluvo-aquic soil region,and the order of grain production efficiency of the provinces(autonomous regions)in the main grain-producing areas was Jilin>Heilongjiang>Inner Mongolia>Jiangxi>Hunan>Sichuan>Hubei>Jiangsu>Liaoning>Henan>Anhui>Shandong>Hebei.From 2001 to 2020,the total factor productivity of grain in the main grain-producing areas increased,but due to the trade-off between the technological progress and the growth of technical efficiency,the increase in the total factor productivity of grain in the main grain-producing areas was small,and the growth mainly came from the increase of input factors in this period.The total factor productivity of grain in Hebei,Heilongjiang,Liaoning,Jilin,Inner Mongolia,Shandong,Jiangsu,Henan and Anhui increased,but the increase was small,while the total factor productivity of grain in Jiangxi,Sichuan,Hunan and Hubei provinces declined. 展开更多
关键词 main grain-producing area grain production efficiency inter-provincial difference
下载PDF
Calculation of Agricultural Production Efficiency Based on a Three-stage Data Envelopment Analysis Model and Analysis of the Spatial-temporal Characteristics: A Case Study of the Yangtze River Economic Belt
4
作者 Wenjun ZHUO Haiyang CUI 《Meteorological and Environmental Research》 CAS 2021年第5期68-76,83,共10页
In response to the strategic call for the " Great Protection" of the Yangtze River Economic Belt and to fulfill the important historical tasks assigned by the state to the provinces and cities of the area,th... In response to the strategic call for the " Great Protection" of the Yangtze River Economic Belt and to fulfill the important historical tasks assigned by the state to the provinces and cities of the area,the Yangtze River Economic Belt is adjusting the agricultural industry structure,optimizing the input-output ratio,and ensuring stable and sustainable agricultural production. Based on the combination of the three-stage Data Envelopment Analysis( DEA) model and cluster analysis,this study examined the Yangtze River Economic Belt from 2008 to 2018 to measure its agricultural production efficiency and to analyze its temporal and spatial characteristics. Studies showed that exogenous environmental factors significantly( P < 5%) impacted agricultural production efficiency in the Yangtze River Economic Zone,and there were temporal and spatial differences. These included:(1) after excluding environmental factors,the overall agricultural production efficiency of the Yangtze River Economic Zone had improved. Sichuan Province and Jiangsu Province were at the forefront of efficiency,whereas the agricultural production efficiency of Shanghai had declined obviously.(2) The agricultural production efficiency of the Yangtze River Economic Belt varied year by year,with fluctuating development. The middle reaches of the Yangtze River had advanced agricultural production efficiency more than the upstream and downstream regions,and the agricultural production efficiency of the individual provinces did not match their economic and social development.(3) Increases in labor,land,irrigation,and other input factors increased agriculture production efficiency,and there was no correlation between fiscal investment,per capita gross domestic product( GDP) and agricultural production efficiency,while the disaster-affected area had a significantly negative impact on agricultural production efficiency. 展开更多
关键词 Agricultural production efficiency Three-stage Date Envelopment Analysis Temporal and spatial characteristics Yangtze River Economic Belt
下载PDF
Increasing Production Efficiency through Casting Quality Improving by Electromagnetic Field Applying
5
作者 Marija Mihailovic Aleksandra Pataric Zvonko GuliSija Miroslav Sokic 《Journal of Mechanics Engineering and Automation》 2012年第1期59-62,共4页
The increased production efficiency of heat treatable A1 alloys, as the result of applied electromagnetic field during continuous casting process was investigated. The applied frequency of the electromagnetic field (... The increased production efficiency of heat treatable A1 alloys, as the result of applied electromagnetic field during continuous casting process was investigated. The applied frequency of the electromagnetic field (EMF) during the AI alloys continuous casting was changing from 30 Hz to 50 Hz, while some castings were obtained without the EMF influence. The mechanical characterization of continuous casted AI alloys EN AW 2007 and En AW 2024 was done on testing machine Zwick/Roell Z 100. The microstructure of as-cast samples was examined, as well. When the frequency decreases (from 50 Hz to 30 Hz), the grain size decreases as well, what is noticeable through the finer microstructure and its uniformity throughout the cross-section. These results have shown that low frequency electromagnetic field significantly influenced the microstructure and therefore the mechanical properties of as cast ingots. Thus, through improved castings quality, operation time and energy savings, the production efficiency was increased. 展开更多
关键词 AI alloys electromagnetic field CASTING production efficiency.
下载PDF
Heterosis Analysis of Nitrogen Use Efficiency for Grain Production of Brassica napus L. 被引量:2
6
作者 石剑飞 殷璀艳 +4 位作者 刘荣 唐瑶 杨光 左青松 冷锁虎 《Agricultural Science & Technology》 CAS 2010年第1期45-47,共3页
[Objective]The aim was to study heterosis of N use efficiency for grain production (NUEg) of Brassica napus L. and provide theoretical basis for breeding N-efficient cultivars. [Method]Dry matter production and N co... [Objective]The aim was to study heterosis of N use efficiency for grain production (NUEg) of Brassica napus L. and provide theoretical basis for breeding N-efficient cultivars. [Method]Dry matter production and N content of six B.napus parents (Zheshuang 3,Yangyou 7,ZJ1,Shilijia,Ningyou 14 and Huyou 16) and their F1 combinations from 6 × 6 complete diallel cross in maturity stage under two N levels were measured; heterosis of NUEg,combining ability and heritability size were analyzed and calculated. [Result]The results showed that NUEg has obvious heterosis; combining ability variance analysis indicated that NUEg was mainly controlled by additive,dominant and cytoplasmic effects; genetic variance analysis showed that additive effects and dominance effects were all significant in low nitrogen fertilizer and dominance effects were significant in high nitrogen fertilizer. [Conclusion]NUEg of B.napus has obvious heterosis. 展开更多
关键词 Brassica napus L. Nitrogen use efficiency for grain production HETEROSIS
下载PDF
Does Security of Land Operational Rights Matter for the Improvement of Agricultural Production Efficiency under the Collective Ownership in China? 被引量:3
7
作者 Xianqing Ji Shouying Liu +1 位作者 Jianan Yan Youyi Li 《China & World Economy》 SCIE 2021年第1期87-108,共22页
Under the"separation of three rights"policy,the impact of security of land operationalrights on agricultural production efficiency has attracted much attention in recentyears.Data envelopment analysis and me... Under the"separation of three rights"policy,the impact of security of land operationalrights on agricultural production efficiency has attracted much attention in recentyears.Data envelopment analysis and mediation effect analysis were applied to 888family farms run by new-type agricultural operators from Songjiang to identify themechanism of the effect of land operational rights security on agricultural productionefficiency through long-term investment.The results show that greater security of landoperational rights generally increased agricultural production efficiency.Approximately37.94 percent of the impact could be explained by long-term investment.The resultsalso indicate that significant heterogeneity exists in the effect of land operational rightssecurity on agricultural production efficiency at various levels of the family farms'efficiency distributions.lt is suggested that government should legalize land operationalrights and give them a status equal to those of households'contractual rights and landownership rights in China's future land tenure reform. 展开更多
关键词 agricultural production efficiency new-type agricultural operator security of land operational rights
原文传递
Spatial differentiation and evolution trend of technical efficiency of forestry production in china
8
作者 Xu Yang 《Proceedings of Business and Economic Studies》 2021年第1期1-5,共5页
Based on the non-radial super-efficiency SBM model,the technical efficiency of forestry production in 30 provinces(municipalities,autonomous regions)across the country was measured from 2004 to 2018,and the Makov chai... Based on the non-radial super-efficiency SBM model,the technical efficiency of forestry production in 30 provinces(municipalities,autonomous regions)across the country was measured from 2004 to 2018,and the Makov chain was introduced to analyze the evolution trend.The research found that:The average PTE of China's forestry from 2004 to 2018 was 0.516,and the overall level was not high;regional imbalances were prominent,showing a distribution pattern of"high in the south and low in the north"and"high in the east and low in the west".Regions with low and high levels of Forestry PTE have certain characteristics of"path dependence".in the long run,Forestry PTE growth will face greater pressure. 展开更多
关键词 FORESTRY production technology efficiency Makov chain
下载PDF
Solution to the Horizontal Crossing Problem of Transportation System at Key Points in Open-Pit Mines
9
作者 Tao DONG Ling LIU 《Asian Agricultural Research》 2024年第7期36-38,47,共4页
In order to reduce the horizontal crossing transportation problems between coal trucks and stripping trucks,large and small vehicles,and transport trucks and belt conveyors at key points of open pit mine in production... In order to reduce the horizontal crossing transportation problems between coal trucks and stripping trucks,large and small vehicles,and transport trucks and belt conveyors at key points of open pit mine in production,the separate transportation mode of underpass bridge and overpass steel trestle is proposed to optimize the open pit development transportation system,so as to solve the practical problems that the horizontal cross of transport vehicles causes vehicle blockage,affects production schedule and production safety.The results show that the horizontal crossing road can be changed into a separate type of overpass steel trestle,which can realize the classified transportation of large and small vehicles,reduce the traffic density,make vehicles with different functions go their own way,eliminate the hidden danger of traffic accidents,and improve the production efficiency. 展开更多
关键词 Open-pit mines Cross-transport Underpass bridge Overpass steel trestle production efficiency
下载PDF
Aboveground biomass and net primary production of semi-evergreen tropical forest of Manipur,north-eastern India 被引量:2
10
作者 L. Supriya Devi P.S Yadava 《Journal of Forestry Research》 SCIE CAS CSCD 2009年第A2期151-155,共5页
The aboveground biomass dynamics and net primary productivity were investigated to assess the productive potential of Dipterocarpus forest in Manipur, Northeast India.Two forest stands(stand I and II) were earmarked r... The aboveground biomass dynamics and net primary productivity were investigated to assess the productive potential of Dipterocarpus forest in Manipur, Northeast India.Two forest stands(stand I and II) were earmarked randomly in the study site for the evaluation of biomass in the different girth classes of tree species by harvest method.The total biomass was 22.50 t·ha-1 and 18.27 t·ha-1 in forest stand I and II respectively.Annual aboveground net primary production varied from 8.86 to 10.43 t·ha-1 respectively in two forest stands(stand I and II).In the present study, the values of production efficiency and the biomass accumulation ratio indicate that the forest is at succession stage with high productive potential. 展开更多
关键词 BIOMASS net primary production ACCUMULATION production efficiency
下载PDF
Aboveground biomass and net primary production of semi-evergreen tropical forest of Manipur, north-eastern India 被引量:1
11
作者 L. Supriya Devi, P.S Yadava 《Journal of Forestry Research》 SCIE CAS CSCD 2009年第2期151-155,I0003,共6页
The aboveground biomass dynamics and net primary productivity were investigated to assess the productive potential of Diptero- carpus forest in Manipur, Northeast India. Two forest stands (stand Ⅰ and Ⅱ) were earm... The aboveground biomass dynamics and net primary productivity were investigated to assess the productive potential of Diptero- carpus forest in Manipur, Northeast India. Two forest stands (stand Ⅰ and Ⅱ) were earmarked randomly in the study site for the evaluation of biomass in the different girth classes of tree species by harvest method. The total biomass was 22.50 t.ha^-1 and 18.27 t.ha^-1 in forest stand I and II respectively. Annual aboveground net primary production varied from 8.86 to 10.43 t.ha^-1 respectively in two forest stands (stand Ⅰ and Ⅱ). In the present study, the values of production efficiency and the biomass accumulation ratio indicate that the forest is at succession stage with high productive potential. 展开更多
关键词 BIOMASS net primary production ACCUMULATION production efficiency
下载PDF
Application of ecological footprint in ecological industrial systems:a study case of maize-MSG production systems
12
作者 Yah Lizhen Cheng Shengkui +1 位作者 Min Qingwen Sun Yehong 《Ecological Economy》 2007年第1期8-17,共10页
To improve the comparability of the research results of ecological industry, the ecological footprint is appliedto analyze the resource utilization and environmental pollution in various subsystems, taking maize-MSG a... To improve the comparability of the research results of ecological industry, the ecological footprint is appliedto analyze the resource utilization and environmental pollution in various subsystems, taking maize-MSG as a case.Results show that the production process from maize to MSG is a extended process of ecological footprint, and that theecological footprint of the maize production is the biggest; the extension of ecological footprint is followed by the increaseof footprint profit, which means that the extension of production chain is an important method to improve the resourcesprofit; the systems have a big proportion of the indirect energy ecological footprint; the air and water pollution in MSGsubsystem is the most serious. At last, it can be identified that ecological footprint is a good method to measure resourceutilization and environmental pollution in various subsystems of an integrated ecological industry. 展开更多
关键词 Ecological footprint MSG production efficiency of resources Ecological industry
下载PDF
Responses of water productivity to irrigation and N supply for hybrid maize seed production in an arid region of Northwest China 被引量:5
13
作者 RAN Hui KANG Shaozhong +4 位作者 LI Fusheng DU Taisheng DING Risheng LI Sien TONG Ling 《Journal of Arid Land》 SCIE CSCD 2017年第4期504-514,共11页
Water and nitrogen(N) are generally two of the most important factors in determining the crop productivity. Proper water and N managements are prerequisites for agriculture sustainable development in arid areas. Fie... Water and nitrogen(N) are generally two of the most important factors in determining the crop productivity. Proper water and N managements are prerequisites for agriculture sustainable development in arid areas. Field experiments were conducted to study the responses of water productivity for crop yield(WP_(Y-ET)) and final biomass(WP_(B-ET)) of film-mulched hybrid maize seed production to different irrigation and N treatments in the Hexi Corridor, Northwest China during April to September in 2013 and also during April to September in 2014. Three irrigation levels(70%–65%, 60%–55%, and 50%–45% of the field capacity) combined with three N rates(500, 400, and 300 kg N/hm^2) were tested in 2013. The N treatments were adjusted to 500, 300, and 100 kg N/hm^2 in 2014. Results showed that the responses of WP_(Y-ET) and WP_(B-ET) to different irrigation amounts were different. WP_(Y-ET) was significantly reduced by lowering irrigation amounts while WP_(B-ET) stayed relatively insensitive to irrigation amounts. However, WP_(Y-ET) and WP_(B-ET) behaved consistently when subjected to different N treatments. There was a slight effect of reducing N input from 500 to 300 kg/hm^2 on the WP_(Y-ET) and WP_(B-ET), however, when reducing N input to 100 kg/hm^2, the values of WP_(Y-ET) and WP_(B-ET) were significantly reduced. Water is the primary factor and N is the secondary factor in determining both yield(Y) and final biomass(B). Partial factor productivity from applied N(PFP_N) was the maximum under the higher irrigation level and in lower N rate(100–300 kg N/hm^2) in both years(2013 and 2014). Lowering the irrigation amount significantly reduced evapotranspiration(ET), but ET did not vary with different N rates(100–500 kg N/hm^2). Both Y and B had robust linear relationships with ET, but the correlation between B and ET(R^2=0.8588) was much better than that between Y and ET(R^2=0.6062). When ET increased, WP_(Y-ET) linearly increased and WP_(B-ET) decreased. Taking the indices of Y, B, WP_(Y-ET), WP_(B-ET) and PFP_N into account, a higher irrigation level(70%–65% of the field capacity) and a lower N rate(100–300 kg N/hm^2) are recommended to be a proper irrigation and N application strategy for plastic film-mulched hybrid maize seed production in arid Northwest China. 展开更多
关键词 water use efficiency water stress nitrogen use efficiency evapotranspiration water productivity for yield water productivity for biomass arid region
下载PDF
Technical efficiency and its determinants of the various cropping systems in the purple-soiled,hilly region of southwestern China 被引量:2
14
作者 ZHANG Shi-chao WEI Chao-fu +1 位作者 SHAO Jing-an WU Zhao-juan 《Journal of Mountain Science》 SCIE CSCD 2016年第12期2205-2223,共19页
This study examines the technical efficiency(TE) differences among typical cropping systems of smallholder farmers in the purple-soiled hilly region of southwestern China.Household-,plot-,and crop-level data and commu... This study examines the technical efficiency(TE) differences among typical cropping systems of smallholder farmers in the purple-soiled hilly region of southwestern China.Household-,plot-,and crop-level data and community surveys were conducted to explore TE levels and determinants of typical cropping systems by using a translog stochastic frontier production function.Results indicate significant difference in TE and its determinants among cropping systems.The mean TEs of the rice cropping system(R),the rice-rape cropping system(RR),the rice-rape-potato cropping system(RRP),and the oil cropping system(O) are0.86,0.90,0.84,and 0.85,respectively,which are over 1.17 times higher than those of the maize-sweet potato-other crop cropping system(MSO) and the maize-sweet potato-wheat cropping system(MSW) at0.78 and 0.69,respectively.Moreover,Technical inefficiency(TIE) of different cropping systems is significantly affected by characteristics of the household as well as plot.However,the impact of land quality,mechanical cultivation conditions,crop structure,farming system,farm radius,household type,cultivated land area per capita,and annual household income per capitalon TIE vary by cropping system.Additionally,output elasticity of land,labor,and capital,as a group,is greater than the one of agricultural machinery and irrigation.Finally,when household-owned effective agricultural labor is at full farming capacity,optimal plot sizes for the R,RR,RRP,MSO,MSW,and 0 cropping systems are 1.12hm^2,0.35 hm^2,0.25 hm^2,2.82 hm^2,1.87 hm^2,and 1.17hm^2,respectively. 展开更多
关键词 Cropping systems Technical efficiency Land management Plot Purple-soil Stochastic Frontier production Function
下载PDF
The Efficiency and Productivity Analyses of the Turkish Banking Sector After the Restructuring Program
15
作者 Tulin Atakan Funda H. Sezgin 《Journal of Modern Accounting and Auditing》 2011年第2期173-181,共9页
After the 2001 economic crisis, the banking sector restructuring program (BSRP) has been designed for the establishment of a stronger financial framework and the improvement of competition in the Turkish banking sec... After the 2001 economic crisis, the banking sector restructuring program (BSRP) has been designed for the establishment of a stronger financial framework and the improvement of competition in the Turkish banking sector. The program constitutes the policies for solving specific problems such as the mismanaged assets of some banks and the recovery of regulating and supervising of the sector. This study aims to analyze the efficiency and productivity changes in the Turkish banking sector during 2002-2009. During this period the Banking Sector Restructuring Program has been applied. The data envolepment analysis (DEA) is conducted for the efficiency measurement under the production and intermediation approaches and it is observed that the efficiency of banks increased for both approaches. The mean efficiency values for the intermediation approach are higher than the values for the production approach, indicating a better functioning in financial intermediation as compared to their operational performance. The Malmquist index based on the intermediation approach is calculated to determine the productivity of the banking sector. It is observed that the productivity of banks increased during the period and the increase resulted mainly from investments in technology. 展开更多
关键词 Turkish banking sector efficiency and productivity banking sector restructuring program data envolepment analysis Malmquist index
下载PDF
Practical Analysis of Mechanical Automation Technology in Automobile Manufacturing
16
作者 Miao Zhang 《Journal of Electronic Research and Application》 2023年第5期24-29,共6页
In today’s rapidly developing modern society,automobiles,as an important part of transportation and industrial fields,play a pivotal role.With the improvement of people’s living standards and the increase in traffic... In today’s rapidly developing modern society,automobiles,as an important part of transportation and industrial fields,play a pivotal role.With the improvement of people’s living standards and the increase in traffic demand,the automobile manufacturing industry has been continuously developing and growing globally.However,to cope with increasingly fierce market competition and ever-changing consumer demands,the automobile manufacturing industry is also facing the challenges of improving production efficiency,reducing costs,and improving product quality.In this context,automation technology has gradually become a major trend in the automobile manufacturing industry.As an important support of modern industry,automation technology has shown great application potential in many fields.From industrial production to daily life,automation technology can be seen everywhere.In the field of manufacturing,especially in automobile manufacturing,the application of automation technology is getting more and more attention.Automated production lines,intelligent robots,and automated warehousing systems have all changed the face of automobile manufacturing to varying degrees,bringing companies higher efficiency,more stable quality,and greater competitive advantages.The application trend of this automation technology in various fields not only meets the needs of modern industry for efficient,precise,and sustainable development but also provides new ideas and paths for the future development of the automobile manufacturing industry. 展开更多
关键词 Mechanical automation technology Automobile manufacturing Practical analysis production efficiency
下载PDF
Functions of Nitrogen,Phosphorus and Potassium in Energy Status and Their Influences on Rice Growth and Development 被引量:2
17
作者 MA Jiaying CHEN Tingting +8 位作者 LIN Jie FU Weimeng FENG Baohua LI Guangyan LI Hubo LI Juncai WU Zhihai TAO Longxing FU Guanfu 《Rice science》 SCIE CSCD 2022年第2期166-178,共13页
Nitrogen(N),phosphorus(P)and potassium(K)are important essential nutrients for plant growth and development,but their functions in energy status remains unclear.Here,we grew Nipponbare rice seedlings in a growth chamb... Nitrogen(N),phosphorus(P)and potassium(K)are important essential nutrients for plant growth and development,but their functions in energy status remains unclear.Here,we grew Nipponbare rice seedlings in a growth chamber for 20 d at 30℃/24℃day/night)under natural sunlight conditions with different nutrient regimes.The results showed that N had the strongest influence on the plant growth and development,followed by P and K.The highest nonstructural carbohydrate content,dry matter weight,net photosynthetic rate(Pn),ATP content,as well as NADH dehydrogenase,cytochrome oxidase and ATPase activities were found in the plants that received sufficient N,P and K.The lowest values of these parameters were detected in the N-deficient plants.Higher dry matter accumulation was observed in the K-deficient than in the P-deficient treatments,but there was no significant difference in the ratio of respiration rate to Pn between these two treatments,suggesting that differences in energy production efficiency may have accounted for this result.This hypothesis was confirmed by higher ATP contents and activities of NADH dehydrogenase,cytochrome oxidase and ATPase in the K-deficient plants than in the P-deficient plants.We therefore inferred different abilities in energy production efficiency among N,P and K in rice seedlings,which determined rice plant growth and development. 展开更多
关键词 RICE nutrient element PHOTOSYNTHESIS RESPIRATION plant growth and development energy production efficiency
下载PDF
Which type of forest management provides most ecosystem services? 被引量:2
18
作者 Timo Pukkala 《Forest Ecosystems》 SCIE CSCD 2016年第3期190-205,共16页
Background: Forest ecosystems are increasingly seen as multi-functional production systems, which should provide, besides timber and economic benefits, also other ecosystem services related to biological diversity, r... Background: Forest ecosystems are increasingly seen as multi-functional production systems, which should provide, besides timber and economic benefits, also other ecosystem services related to biological diversity, recreational uses and environmental functions of forests. This study analyzed the performance of even-aged rotation forest management (RFM), continuous cover forestry (CCF) and any-aged forestry (AAF) in the production of ecosystem services. AAF allows both even-aged and uneven-aged management schedules. The ecosystem services included in the analyses were net present value, volume of harvested timber, cowberry and bilberry yields, scenic value of the forest, carbon balance and suitability of the forest to Siberian jay. Methods: Data envelopment analysis was used to derive numerical efficiency ratios for the three management systems. Efficiency ratio is the sum of weighted outputs (ecosystem services) divided by the sum of weighted inputs. The linear programing model proposed by Charnes, Cooper and Rhodes was used to derive the weights for calculating efficiency scores for the silvicultural systems. Results and conclusions: CCF provided more ecosystem services than RFM, and CCF was more efficient than RFM and AAF in the production of ecosystem services. Multi-objective management provided more ecosystem services (except harvested timber) than single-objective management that maximized economic profitability. The use of low discount rate (resulting in low cutting level and high growing stock volume) led to better supply of most ecosystems services than the use of high discount rate. RFM where NPV was maximized with high discount rate led to particularly poor provision of most ecosystem services. In CCF the provision of ecosystem services was less sensitive to changes in discount rate and management objective than in RFM. 展开更多
关键词 Data envelopment analysis production efficiency Multi-objective management Multi-functional forestry Continuous cover forestry Rotation forest management Any-aged forestry
下载PDF
Population status and regeneration of a tropical clumping bamboo Schizostachyum dullooa under two management regimes
19
作者 Arun Jyoti Nath Ashesh Kumar Das 《Journal of Forestry Research》 SCIE CAS CSCD 2011年第1期43-46,共4页
Schizostachyum dullooa (Gamble) Majumder 'dolu bamboo' is a thin walled sympodial moderate sized to large tufted bamboo, dominant in the successional fallows of northeast India. The impact of resource management o... Schizostachyum dullooa (Gamble) Majumder 'dolu bamboo' is a thin walled sympodial moderate sized to large tufted bamboo, dominant in the successional fallows of northeast India. The impact of resource management on productivity and sustainability of the species was evaluated by investigating the population status and regeneration in Cachar tropical semi evergreen forest under private property resource management (PPRM) and common property resource management (CPRM) regimes. Population status revealed current-year, one-year, two-year and three-year-old culms contribute 54%, 24%, 16% and 6% of the total culms per clump, respectively, under PPRM. Three-year-old culms were absent in CPRM and population status was thus represented by current year (83%), one-year (16%) and two-year (1%) old culms. Net change, rate of change and % gain in population for different age classes showed the prevalence of management practices under CPRM was unscientific. Efficiency of new culm production per clump used as an index of regeneration was 69.7% in PPRM and 59.88% in CPRM. New culms produced under CPRM were small and thin. We conclude that CPRM is inappropriate for a long term economic and ecological sustainability of the species and alternative management protocols are needed for conservation of the species. 展开更多
关键词 management regime population structure production efficiency Schizostachyum dullooa
下载PDF
Synthesis and Photo-acid Generation of a Novel Bis(trichloromethyl)-1,3,5-triazine
20
作者 JIANG Yu-ren LI Jin-liang XU Hui 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2009年第6期870-875,共6页
A new environmentally friendly photo-acid generator(PAG), 1-{4'-[4,6-bis(trichloromethyl)-1,3,5-triazin- 2-yl] [ 1, 1'-biphenyl]-4-yl}-O-acetyloxime ethanone(TZ4) consisting of both an oxime ester group and a ... A new environmentally friendly photo-acid generator(PAG), 1-{4'-[4,6-bis(trichloromethyl)-1,3,5-triazin- 2-yl] [ 1, 1'-biphenyl]-4-yl}-O-acetyloxime ethanone(TZ4) consisting of both an oxime ester group and a triazine group was designed and synthesized. From the measurements of absorption, fluorescence and the photo-acid generation, it was found that the novel PAG has an excellent radical-generating efficiency. And the other three bis-(trichloromethyl) triazine derivatives 2-[2-(4-methoxyphenyl)ethenyl]-4,6-bis(trichloromethyl)-l,3,5-triazine(TZ1), 2-[2-(3,4-dimethoxyphenyl)ethenyl]-4,6-bis(trichloromethyl)-1,3,5-triazine(TZ2) and 2-(1,3-benzodioxol-5-yl)-4,6-bis(trichloromethyl)-1,3,5-triazine(TZ3) were synthesized and studied in this work. In the acid measurement, the acid-forming performance of S-triazinyl derivatives was evaluated by the method ascertained in our laboratory. The results indicate that the novel triazine has the better acid-forming performance that subsequently catalyzes the deblocking of a protecting group in copolymers. 展开更多
关键词 TRIAZINE Photo-acid generator Photo-sensitizer Acid production efficiency
下载PDF
上一页 1 2 下一页 到第
使用帮助 返回顶部