期刊文献+
共找到1,554篇文章
< 1 2 78 >
每页显示 20 50 100
基于TOPSIS和灰色关联投影法的区域碳效率动态综合评价——以泛珠三角为例
1
作者 何燕子 王妍 《湖南工业大学学报》 2023年第6期61-68,共8页
为弥补传统碳效率评价偏向绝对量指标或者少数几个指标的单点式评价的不足,选取相对量指标,从经济、人口、福利多个维度并兼顾地区发展实际与公平原则,构建区域碳效率评价指标体系。将TOPSIS法与灰色关联投影分析相结合,并利用时间序列... 为弥补传统碳效率评价偏向绝对量指标或者少数几个指标的单点式评价的不足,选取相对量指标,从经济、人口、福利多个维度并兼顾地区发展实际与公平原则,构建区域碳效率评价指标体系。将TOPSIS法与灰色关联投影分析相结合,并利用时间序列平均算子二次加权以实现对泛珠三角9省(自治区)2011—2020年碳效率的动态综合评价。静态与动态评价研究结果显示:该区域碳效率发展水平存在差异,其中海南省碳效率总体水平较高,为0.530;贵州省碳效率相对较低,为0.162;海南省比贵州省高出227%。福建省碳效率呈上升趋势,由2011年的0.327上升至2020年的0.498,增长了52.3%。研究认为,应该制定差异化减排策略、加大技术经费投入、增强社会福利、引进人才以实现低碳经济发展。 展开更多
关键词 泛珠三角 效率 TOPSIS 灰色关联投影法
下载PDF
文化产业上市公司绩效评价——基于超效率DEA和Malmquist指数 被引量:52
2
作者 郭淑芬 郝言慧 王艳芬 《经济问题》 CSSCI 北大核心 2014年第2期75-78,共4页
运用超效率DEA模型和Malmquist指数法对30家文化产业上市公司进行了绩效评价。从DEA结果来看,30家文化产业上市公司只有8家上市公司达到DEA有效,上市公司整体绩效一般;从Malmquist全要素生产率( TFP)指数看,文化产业上市公司的全... 运用超效率DEA模型和Malmquist指数法对30家文化产业上市公司进行了绩效评价。从DEA结果来看,30家文化产业上市公司只有8家上市公司达到DEA有效,上市公司整体绩效一般;从Malmquist全要素生产率( TFP)指数看,文化产业上市公司的全要素生产率指数2011~2012年窗口期间的增长率为-4.8%,技术进步率下降是造成TFP负增长的重要原因,因此应加大技术研发投入,重视技术进步。 展开更多
关键词 文化产业 上市公司
下载PDF
中国西部地区省际全要素能源效率研究——基于超效率DEA模型和Malmquist指数 被引量:14
3
作者 关爱萍 师军 张强 《工业技术经济》 北大核心 2014年第2期32-40,共9页
本文基于超效率DEA模型,测算出2000~2011年中国西部11个省考虑环境效应的全要素能源效率,并运用Malmquist指数法将全要素能源效率指数分解为技术进步指数和技术效率指数,最后利用Tobit模型对全要素能源效率影响因素进行了分析。结... 本文基于超效率DEA模型,测算出2000~2011年中国西部11个省考虑环境效应的全要素能源效率,并运用Malmquist指数法将全要素能源效率指数分解为技术进步指数和技术效率指数,最后利用Tobit模型对全要素能源效率影响因素进行了分析。结果表明:西部各省能源效率差距较大,其中,内蒙古、重庆和青海的能源效率较高,广西、贵州、云南和甘肃的能源效率比较低;样本期间,西部地区平均全要素能源效率下降了0.4%,技术进步是能源效率变动的主要因素;第二产业和第三产业发展对西部地区能源效率提升有促进作用,能源价格、煤炭消费以及区际产业转移的上升对西部地区能源效率提升有抑制作用。 展开更多
关键词 全要素能源效率 MALMQUIST指数 TOBIT模型
下载PDF
江苏旅游业发展效率及对策研究——基于超效率DEA和Malmquist指数分析 被引量:23
4
作者 龚艳 郭峥嵘 《华东经济管理》 CSSCI 2014年第4期7-12,17,共7页
文章利用超效率DEA模型和Malmqulst指数模型分别测算了江苏13市2001-2012年旅游业发展的静态效率与动态效率。结果显示:江苏旅游业静态效率保持先降后升的态势,从2001年的0.848下降到2006年的0.611,后又上升到2012年的0.824,12年间效率... 文章利用超效率DEA模型和Malmqulst指数模型分别测算了江苏13市2001-2012年旅游业发展的静态效率与动态效率。结果显示:江苏旅游业静态效率保持先降后升的态势,从2001年的0.848下降到2006年的0.611,后又上升到2012年的0.824,12年间效率均值为0.726。各市旅游业效率存在显著的地区差异,且呈现逐步扩大的趋势。江苏旅游业动态效率(TFP)年均变化值-0.6%,增长主要来源于技术进步而不是规模效率的作用。在以上研究的基础上,提出提升江苏旅游业效率的对策,为旅游业持续、高效、健康发展提供理论参考。 展开更多
关键词 旅游业效率 MALMQUIST指数
下载PDF
A study on the simulation of carbon and water fluxes of Dangxiong alpine meadow and its response to climate change 被引量:1
5
作者 Lingyun He Lei Zhong +3 位作者 Yaoming Ma Yuting Qi Jie Liu Peizhen Li 《Atmospheric and Oceanic Science Letters》 CSCD 2024年第5期22-27,共6页
The alpine meadow ecosystem accounts for 27%of the total area of the Tibetan Plateau and is also one of the most important vegetation types.The Dangxiong alpine meadow ecosystem,located in the south-central part of th... The alpine meadow ecosystem accounts for 27%of the total area of the Tibetan Plateau and is also one of the most important vegetation types.The Dangxiong alpine meadow ecosystem,located in the south-central part of the Tibetan Plateau,is a typical example.To understand the carbon and water fluxes,water use efficiency(WUE),and their responses to future climate change for the alpine meadow ecosystem in the Dangxiong area,two parameter estimation methods,the Model-independent Parameter Estimation(PEST)and the Dynamic Dimensions Search(DDS),were used to optimize the Biome-BGC model.Then,the gross primary productivity(GPP)and evapotranspiration(ET)were simulated.The results show that the DDS parameter calibration method has a better performance.The annual GPP and ET show an increasing trend,while the WUE shows a decreasing trend.Meanwhile,ET and GPP reach their peaks in July and August,respectively,and WUE shows a“dual-peak”pattern,reaching peaks in May and November.Furthermore,according to the simulation results for the next nearly 100 years,the ensemble average GPP and ET exhibit a significant increasing trend,and the growth rate under the SSP5–8.5 scenario is greater than that under the SSP2–4.5 scenario.WUE shows an increasing trend under the SSP2–4.5 scenario and a significant increasing trend under the SSP5–8.5 scenario.This study has important scientific significance for carbon and water cycle prediction and vegetation ecological protection on the Tibetan Plateau. 展开更多
关键词 Carbon and water flux Water use efficiency Alpine meadow Biome-BGC model Climate change
下载PDF
Performance improvement in stepped solar still modified by sponge layer
6
作者 Mahtab TARAHOMI Saman RASHIDI +1 位作者 Faramarz HORMOZI Shahabeddin ASHTIANI 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第6期1973-1982,共10页
In this paper,the experimental investigation on the performance improvement of conventional stepped solar still is conducted.The steps are covered by the porous material to improve the performance of the conventional ... In this paper,the experimental investigation on the performance improvement of conventional stepped solar still is conducted.The steps are covered by the porous material to improve the performance of the conventional device and increase the evaporation rate.All the parameters,including the temperature on the glass surface,the water temperature inside the evaporation zone,and the amount of water produced in both conventional and modified stepped solar stills are measured and compared.The efficiency of two devices and their exergy efficiency have been calculated.Finally,the economic analysis of both devices has been done to check the economic feasibility of the modified device.The amount of freshwater generated during one day was 2244.4 and 3076.2 mL/m^(2),respectively for the conventional and modified stepped solar stills.As a result,the amount of water produced in one day by modified stepped solar still is 35.5% more than the conventional one.Also,the costs for the conventional and modified stepped solar stills have been calculated as 0.0359 and 0.029$/(L·m^(-2)),respectively. 展开更多
关键词 stepped solar still black sponge EFFICIENCY EXERGY economic analysis
下载PDF
Formation mechanism of nanopores in dense films of anodic alumina
7
作者 Peng-ze LI Yu ZHANG +5 位作者 Jia-zheng ZHANG Lin LIU Shi-yi WANG Rui LIU Ye SONG Xu-fei ZHU 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2024年第9期2918-2927,共10页
Constant-current anodization of pure aluminum was carried out in non-corrosive capacitor working electrolytes to study the formation mechanism of nanopores in the anodic oxide films.Through comparative experiments,nan... Constant-current anodization of pure aluminum was carried out in non-corrosive capacitor working electrolytes to study the formation mechanism of nanopores in the anodic oxide films.Through comparative experiments,nanopores are found in the anodic films formed in the electrolytes after high-temperature storage(HTS)at 130°C for 240 h.A comparison of the voltage-time curves suggests that the formation of nanopores results from the decrease in formation efficiency of anodic oxide films rather than the corrosion of the electrolytes.FT-IR and UV spectra analysis shows that carboxylate and ethylene glycol in electrolytes can easily react by esterification at high temperatures.Combining the electronic current theory and oxygen bubble mold effect,the change in electrolyte composition could increase the electronic current in the anodizing process.The electronic current decreases the formation efficiency of anodic oxide films,and oxygen bubbles accompanying electronic current lead to the formation of nanopores in the dense films.The continuous electronic current and oxygen bubbles are the prerequisites for the formation of porous anodic oxides rather than the traditional field-assisted dissolution model. 展开更多
关键词 anodic alumina formation mechanism NANOPORES formation efficiency electronic current oxygen bubble
下载PDF
Supported Ziegler-Natta catalysts from MgCl_(2)·nROH precursors and its catalytic behaviors for diene copolymerization
8
作者 FAN Xun-zhang ZHAO Yuan-jin +1 位作者 LUO Shu-fang HE Ai-hua 《合成橡胶工业》 CAS 2024年第4期348-348,共1页
Heterogeneous TiCl4/MgCl_(2) type Ziegler-Natta(Z-N)catalysts with unique advantages like low cost,high activity,high stereoregularity and pretty particle morphology,contribute to more than 130 Mt polyolefin large-sca... Heterogeneous TiCl4/MgCl_(2) type Ziegler-Natta(Z-N)catalysts with unique advantages like low cost,high activity,high stereoregularity and pretty particle morphology,contribute to more than 130 Mt polyolefin large-scale production.However,most researches related with heterogeneous Z-N catalysts focused onα-olefin polymerizations like ethylene,propylene,etc. 展开更多
关键词 CATALYSTS REGULARITY PROPYLENE
下载PDF
Effects of Collocational Congruency,Frequency and L2 Proficiency on the Processing of English Adjective-Noun Collocations
9
作者 Lianrui YANG Qun ZHANG +1 位作者 Ni LI Ying CHEN 《Chinese Journal of Applied Linguistics》 2024年第3期393-413,524,共22页
The present study investigates the effects of congruency and frequency on adjective-noun collocational processing for Chinese learners of English at two proficiency levels based on the data obtained in an online accep... The present study investigates the effects of congruency and frequency on adjective-noun collocational processing for Chinese learners of English at two proficiency levels based on the data obtained in an online acceptability judgment task.The subject pool of this research included 60 English majors studying at a university in China;30 were selected as a higher-proficiency group and 30 as a lower-proficiency group according to their Vocabulary Levels Test(Schmitt et al.,2001)scores and their self-reported proficiency in English.The experimental materials were programmed to E-prime 2.0 and included six types of collocations:(1)15 high-frequency congruent collocations,(2)15 low-frequency congruent collocations,(3)15 high-frequency incongruent collocations,(4)15 low-frequency incongruent collocations,(5)15 Chinese-only items,and(6)75 unrelated items for baseline data.The collected response times(RTs)and accuracy rates data were statistically analyzed by the use of an ANOVA test and pairwise comparisons through SPSS 16.0 software.The results revealed that:(1)the adjective-noun collocational processing of Chinese English learners is influenced by collocational frequency,congruency and L2 proficiency;(2)the processing time is affected by the interaction of congruency and frequency;and(3)the interactive effect of L2 proficiency in conjunction with congruency and frequency also influences the processing quality. 展开更多
关键词 adjective-noun collocations congruency effects frequency effects L2 proficiency
下载PDF
Research on Automatic Test System of Engine Blade Natural Frequency
10
作者 LU Yonghua LIU Jingjing +2 位作者 YANG Haibo HUANG Chuan MA Zhicheng 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2024年第4期476-487,共12页
Blades are one of the important components on aircraft engines.If they break due to vibration failure,the normal operation of the entire engine will be offected.Therefore,it is necessary to measure their natural frequ... Blades are one of the important components on aircraft engines.If they break due to vibration failure,the normal operation of the entire engine will be offected.Therefore,it is necessary to measure their natural frequency before installing them on the engine to avoid resonance.At present,most blade vibration testing systems require manual operation by operators,which has high requirements for operators and the testing process is also very cumbersome.Therefore,the testing efficiency is low and cannot meet the needs of efficient testing.To solve the current problems of low testing efficiency and high operational requirements,a high-precision and high-efficiency automatic test system is designed.The testing accuracy of this system can reach ±1%,and the testing efficiency is improved by 37% compared to manual testing.Firstly,the influence of compression force and vibration exciter position on natural frequency test is analyzed by amplitude-frequency curve,so as to calibrate servo cylinder and fourdimensional motion platform.Secondly,the sine wave signal is used as the excitation to sweep the blade linearly,and the natural frequency is determined by the amplitude peak in the frequency domain.Finally,the accuracy experiment and efficiency experiment are carried out on the developed test system,whose results verify its high efficiency and high precision. 展开更多
关键词 BLADE vibration failure natural frequency automatic test system
下载PDF
微管壳式换热器在能量转换循环中的应用 被引量:1
11
作者 高娇 丁文杰 +3 位作者 黄洪文 郭海兵 马纪敏 王少华 《强激光与粒子束》 CAS CSCD 北大核心 2023年第11期122-131,共10页
目前,超临界二氧化碳(S-CO_(2))布雷顿循环普遍采用印刷电路板换热器(PCHE)来保证其相对其他能量转换循环的紧凑性优势。PCHE芯体为整体结构,若内部出现泄漏或结垢等问题,很难进行维护与检修。本文提出了一种微管壳式换热器(MSTE),其结... 目前,超临界二氧化碳(S-CO_(2))布雷顿循环普遍采用印刷电路板换热器(PCHE)来保证其相对其他能量转换循环的紧凑性优势。PCHE芯体为整体结构,若内部出现泄漏或结垢等问题,很难进行维护与检修。本文提出了一种微管壳式换热器(MSTE),其结构与传统管壳式换热器类似,但其管径缩小至微通道级。由于MSTE的流道横截面积占总截面积之比较PCHE大,在典型的回热器与冷却器设计工况下,相对PCHE而言,采用MSTE可将体积与质量均减小30%以上。灵敏性分析结果显示,采用本文设计的MSTE结构的回热器与冷却器,回热器冷热流道入口温度升高20℃左右,压缩机入口温度变化均不超过1℃,说明该种结构换热器的换热能力足够支撑能量转换循环的一般工况波动。 展开更多
关键词 微管壳式换热器 超临界二氧化碳 回热器 冷却器
下载PDF
不同运动模式下耗氧量动力特征参数关系研究 被引量:5
12
作者 胡国鹏 冯魏 +3 位作者 冯刚 王振 刘无逸 孟妍 《体育科学》 CSSCI 北大核心 2015年第11期45-51,共7页
目的:研究两种典型运动模型下耗氧动力学特征并分析其特征参数之间关系。方法:34名受试者分别进行一次斜坡式递增负荷力竭测试和3次中等强度下的动力学重复测试,用线性和非线性函数模型拟合耗氧量变化的特征参数。结果:斜坡式递增... 目的:研究两种典型运动模型下耗氧动力学特征并分析其特征参数之间关系。方法:34名受试者分别进行一次斜坡式递增负荷力竭测试和3次中等强度下的动力学重复测试,用线性和非线性函数模型拟合耗氧量变化的特征参数。结果:斜坡式递增负荷模式中,耗氧量(VO2)和功率(Waat)的一次线性函数拟合优度R2为0.932±0.151(P〈0.01);而通气量(VE)和VO2的非线性对数函数拟合优度群为0.977±0.012(P〈0.01);中等强度重复运动中,其VO2随时间变化的指数函数拟合优度R2为0.96±0.02(P〈0.01);耗氧动力学参数△效率(Delta Efficiency)Aslop与最大耗氧量(VO2max)绝对值、相对值及通气无氧阈(VT)相关系数介于0.600~0.757(P〈0.01);耗氧效率坡度(Oxygen Uptake Efficiency Slop,OUES)AOUES与VO2max的相关系数为0.756、0.600(P〈0.01);而中等强度下的氧动力学参数τ(Tau)与aslop、AOUES无显著性关系(P〉0.05)。结论:斜坡式递增负荷测试中,VO2和Waat等呈现不同的函数特征;所衍生的特征参数△效率、OUES与VO2max及VT存在不同程度的中高度相关,在耐力评定中具有一定参考价值;而中等强度下的氧动力学参数和上述指标无明显关系。 展开更多
关键词 耗氧量动力学 最大耗氧量 △效率 耗氧效率坡度
下载PDF
Research progress of magnesium anodes and their applications in chemical power sources 被引量:11
13
作者 王乃光 王日初 +3 位作者 彭超群 胡程旺 冯艳 彭兵 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第8期2427-2439,共13页
Magnesium is a promising metal used as anodes for chemical power sources. This metal could theoretically provide negative discharge potential and exhibit large capacity during the discharge process. However, when the ... Magnesium is a promising metal used as anodes for chemical power sources. This metal could theoretically provide negative discharge potential and exhibit large capacity during the discharge process. However, when the magnesium anode is adopted for practical applications, several issues, such as the discharge products adhered to the electrode surface, the self-discharge occurring on the anode material, and the detachment of metallic particles, adversely affect its inherently good discharge performance. In this work, the types of chemical power sources using magnesium as anodes were elaborated, and the approaches to enhance its anode performance were analyzed. 展开更多
关键词 magnesium anode discharge activity anodic efficiency activation mechanism ELECTROLYTE
下载PDF
Effects of Different Water Stresses on Eco-physiological Characteristics of Hippophae rhamnoides Seedlings 被引量:37
14
作者 郭卫华 李波 +2 位作者 黄永梅 赵海霞 张新时 《Acta Botanica Sinica》 CSCD 2003年第10期1238-1244,共7页
In order to examine the effects of the decrease of future precipitation on the eco-physiological characteristics of sea buckthorn (Hippophae rhamnoides Linn.) in Huangfuchuan Watershed in Nei Mongol, a water gradient ... In order to examine the effects of the decrease of future precipitation on the eco-physiological characteristics of sea buckthorn (Hippophae rhamnoides Linn.) in Huangfuchuan Watershed in Nei Mongol, a water gradient experiment was conducted based on the four specially designed water supply levels, including normal precipitation, slight drought, drought and extreme drought. Results of ANOVE showed that different water gradients had a significant effect on (1) microhabitat factors, such as soil water content and soil temperature; (2) gas exchange, such as net photosynthetic rate, stomatal conductance and transpiration rate; (3) resource use efficiency; and (4) leaf water potential. Water use efficiency of H rhamnoides could increase under moderate water stress, i.e. drought condition, while its net photosynthetic rate and transpiration rate decreased. All kinds of eco-physiological characteristics proved H. rhamnoides seedlings under all water supplies were affected by water stress more or less and that mechanism of intrinsic physiological regulation in seedlings under the extreme drought conditions had the appearance of turbulence to a certain extent. Therefore, H rhamnoides seedlings in Huangfuchuan Watershed could not acclimate to extreme drought conditions. 展开更多
关键词 water stress Hippophae rhamnoides Huangfuchuan Watershed gas exchange water potential resource use efficiency DROUGHT
下载PDF
Measuring technical efficiency of Chinese nonferrous metals enterprises on a background of industry consolidation 被引量:5
15
作者 危平 唐慧泉 +1 位作者 陈瑶 陈晓红 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第9期2797-2806,共10页
Since 2009, Chinese nonferrous metals industry has been carried out industry consolidation with strong support by the central government. This work examined technical efficiency of Chinese nonferrous metals firms and ... Since 2009, Chinese nonferrous metals industry has been carried out industry consolidation with strong support by the central government. This work examined technical efficiency of Chinese nonferrous metals firms and its change during the period of 2007 and 2011. Based on financial data from nonferrous metals listed companies, technical efficiency of nonferrous metal minerals mining firms and nonferrous metal smelting, pressing and processing firms was estimated respectively using the data envelopment analysis (DEA) method. It was found that, in both sectors, number of pure technical and scale inefficient firms dominated over efficient ones. Overall, their technical and scale efficiency tended to be very low after 2009. In particular, efficiency scores of nonferrous metal smelting, pressing and processing firms fluctuated greatly during the research period. And a limited number of large leading firms were able to maintain 100% efficiency score in the industry, while efficiency of most of other leading firms has declined since 2009. 展开更多
关键词 industry consolidation nonferrous metals finns data envelopment analysis (DEA) technical efficiency scale efficiency CONGLOMERATE
下载PDF
Effect of N Fertilization on Yield, N Absorption and Utilization of Two Species of Super High-Yielding Summer Maize 被引量:6
16
作者 王宜伦 刘天学 +2 位作者 谭金芳 张许 李潮海 《Agricultural Science & Technology》 CAS 2012年第2期339-342,374,共5页
[Objective] The aim was to study on effects of N fertilizer on yield, N absorption and utilization of different cultivars of super high-yielding summer maize, in order to provide reference for reasonable N fertilizati... [Objective] The aim was to study on effects of N fertilizer on yield, N absorption and utilization of different cultivars of super high-yielding summer maize, in order to provide reference for reasonable N fertilization in accordance with different cultivars. [Method] Field experiment was conducted to study on effects of different N fertilizers on yield, N absorption and use efficiency of Zhengdan 958 and Xundan 20, in order to learn the effect differences at different N fertilizer levels. [Result] After N was applied, yields of the two summer maize increased significantly. Zhengdan 958 achieved the highest in yield and proceeds at 12 051.18 kg/hm2 and 1 722.40 yuan/hm2, respectively in low N level. In contrast, Xundan 20 achieved the highest at 13 166.00 kg/hm2 and 1 343.92 yuan/hm2 in the above two aspects in high N level. Compared with Zhengdan 958, Xundan 20 increased by 9.90%, 5.20% and 12.00% in N levels of 0, 240, and 450 kg/hm2, respectively. When N fertilizers were applied, protein yield of Xundan 20 was significantly higher than that of Zhengdan 958, so that higher N fertilizers contributed higher protein yield for Xundan 20. In high N level, N efficiency, N-fertilizer utilization and partial productivity of Xundan 20 were significantly higher than that of Zhengdan 958. [Conclusion] Lower N-fertilizer was suitable for Zhengdan 958 and Xundan 20 would get a good harvest if more N-fertilizers were applied. The results provided references for reasonable N fertilization. 展开更多
关键词 Super high-yielding Summer maize CULTIVAR N-FERTILIZER YIELD Accumulation of N N efficiency
下载PDF
Agrobacterium _mediated Transformation of Rice with Help of Bombardment 被引量:10
17
作者 明小天 苑华毅 +1 位作者 王莉江 陈章良 《Acta Botanica Sinica》 CSCD 2001年第1期72-76,共5页
Oryza sativa L. ssp. japonica cv. Zhonghua 8, which is recalcitrant to infection of Agrobacterium tumefaciens (Smith et Townsend) Conn strain EHA105 with ordinary binary vector pCambia 1301, was transformed through Ag... Oryza sativa L. ssp. japonica cv. Zhonghua 8, which is recalcitrant to infection of Agrobacterium tumefaciens (Smith et Townsend) Conn strain EHA105 with ordinary binary vector pCambia 1301, was transformed through Agrobacterium-mediated transformation with help of bombardment. The transformation efficiency can be raised greatly. Single copy of gene insertion in the genome of transgenic rice plants was proved by Southern analysis and the expression of GUS gene was observed. GUS gene and hygromycin-resistant gene show 3:1 segregation in progenies of the transgenic rice plants. 展开更多
关键词 AGROBACTERIUM BOMBARDMENT TRANSFORMATION RICE
下载PDF
Effects of Different Irrigation Amounts on Water Consumption and Water Use Efficiency of Greenhouse Cucumber 被引量:6
18
作者 郭生虎 孔德杰 +2 位作者 张源沛 郑国宝 朱金霞 《Agricultural Science & Technology》 CAS 2010年第9期217-220,共4页
[Objective] This study was to investigate the effects of different irrigation amount on water consumption and water use efficiency of greenhouse cucumber.[Method]Under the condition of drip irrigation with different w... [Objective] This study was to investigate the effects of different irrigation amount on water consumption and water use efficiency of greenhouse cucumber.[Method]Under the condition of drip irrigation with different water amounts in sunlight greenhouse of the arid areas in Ningxia,the soil water was measured and the water consumption of crop was calculated.[Result]When irrigation amount was 563 mm,the water consumption as a whole gradually increased with the delay of growth period,reached peak during the thriving stage of fruit setting,and then gradually declined;in each treatment,the daily water consumption increased with the increasing of irrigation amount during each growth period.However,the consumption of soil moisture reduced with the significant increase of irrigation.563 mm of irrigation amount could meet the water requirements of cucumber and began to add water to soil,and water utilization efficiency could reach 33.4 kg/m3.[Conclusion]The research had provided theoretical basis for water management in the production process of greenhouse cucumber. 展开更多
关键词 GREENHOUSE CUCUMBER Irrigation amount Water consumption Water utilization efficiency
下载PDF
Effect of oxide and fluoride addition on electrolytic preparation of Mg-La alloy in chloride molten salt 被引量:3
19
作者 王世栋 李权 +2 位作者 叶秀深 孙庆国 吴志坚 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第10期3104-3111,共8页
Mg-La alloys were prepared by constant voltage electrolysis in the molten salt system of MgC12-LaC13-KC1 at 750℃, with a graphite crucible as the anode and a tungsten rod as the cathode. The effect of oxide and fluor... Mg-La alloys were prepared by constant voltage electrolysis in the molten salt system of MgC12-LaC13-KC1 at 750℃, with a graphite crucible as the anode and a tungsten rod as the cathode. The effect of oxide and fluoride addition on the electrolysis was investigated comprehensively. X-ray diffraction (XRD) was used to characterize some of the Mg-La alloy products and the sludges. As the content of MgO or La203 in the electrolyte increased, both the current efficiency and the mass of alloy product decreased, indicating that both MgO and La203 may take part in the reactions in the electrolyte. When the same mass of the oxide was added, compared with La203, MgO had a more pronounced effect on both the current efficiency and the mass of alloy product. XRD studies confirmed the formation of LaOC1 when MgO or LazO3 was added into the electrolyte. The formation of LaOCl sludge would be the main reason for the negative effect of the oxide addition on both the current efficiency and the mass of alloy. In the electrolytic system, the addition of CaF2 was not helpful to suppress the negative effect of MgO on the electrolysis, probably due to the complex reactions of the La compounds in the electrolyte. 展开更多
关键词 Mg-La alloy molten salt ELECTROLYSIS OXIDE FLUORIDE current efficiency
下载PDF
Quantitative Description of the Effects of Sweep Efficiency and Displacement Efficiency during Chemical Flooding on a Heterogeneous Reservoir 被引量:6
20
作者 沈平平 袁士义 +2 位作者 邓宝荣 宋杰 沈奎友 《Petroleum Science》 SCIE CAS CSCD 2004年第3期41-48,77,共9页
The processes of flooding—water flooding, polymer flooding and ternary combination flooding—were simulated respectively on a 2-D positive rhythm profile geological model by using the ASP numerical modeling softw... The processes of flooding—water flooding, polymer flooding and ternary combination flooding—were simulated respectively on a 2-D positive rhythm profile geological model by using the ASP numerical modeling software developed by RIPED (Yuan, et al. 1995). The recovery coefficient, remaining oil saturation, sweep efficiency and displacement efficiency were calculated and correlated layer by layer. The results show that the sweep efficiency and displacement efficiency work different effects on different layers in the severely heterogeneous reservoir. The study shows that the displacement efficiency and sweep efficiency play different roles in different layers for severely heterogeneous reservoirs. The displacement efficiency contributes mainly to the high permeability zones, the sweep efficiency to the low permeability zones, both of which contribute to the middle permeable zones. To improve the sweep efficiency in the low permeability zones is of significance for enhancing the whole recovery of the reservoir. It is an important path for improving the effectiveness of chemical flooding in the severely heterogeneous reservoirs to inject ternary combination slug after profile control. 展开更多
关键词 Chemical flooding displacement efficiency sweep efficiency recovery efficiency heterogenous reservoir
下载PDF
上一页 1 2 78 下一页 到第
使用帮助 返回顶部