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
An 8-week feeding trial was conducted to determine the optimal dietary protein-to-lipid ratio for juvenile Nibea albiflora with an initial weight of(11.76 ± 0.20) g.Nine experimental diets containing different co...An 8-week feeding trial was conducted to determine the optimal dietary protein-to-lipid ratio for juvenile Nibea albiflora with an initial weight of(11.76 ± 0.20) g.Nine experimental diets containing different concentrations of protein(40%,47%,or 54%) and lipids(5%,9%,or 13%) in a 3 × 3 factorial experimental design were tested in triplicate groups of fish,while the protein-to-energy(P/E) ratios of the diets varied in the range of 19.74–28.32 mg k J^(-1).Results showed that fish fed diets containing 9% or 13% lipids with 54% protein exhibited significantly higher weight gains and specific growth rates than those fed other diets.The feed conversion rate of fish fed the diet with 40% protein and 5% lipids was significantly poorer than that of fish fed other diets.The protein efficiency rate of fish fed diets with 5% lipids was significantly lower than that of fish fed 9% or 13% lipid diets.Carcass lipid and energy contents were positively correlated with dietary lipid level regardless of protein level.Fish fed a 54% protein diet showed the highest trypsin activity.The intestinal lipase activity of fish fed the diet containing 13% lipids was significantly higher than that of fish fed 5% or 9% lipid diets.These results demonstrate the high protein dietary requirements of N.albiflora.A diet containing 54% protein and 9%–13% lipids with a P/E ratio of 26.2–27.81 mg protein k J^(-1) can be considered optimal for juvenile N.albiflora.展开更多
Food waste has developed as an alternative for the production of renewable fuels such as biogas from AD （anaerobic digestion）. In relation to the biogas production rate, digester temperature setting is one of the ve...Food waste has developed as an alternative for the production of renewable fuels such as biogas from AD （anaerobic digestion）. In relation to the biogas production rate, digester temperature setting is one of the very important factors for digester operation, especially in low temperature countries. In this study, the effect of digester temperature on biogas and methane production efficiency in the AD of food waste was evaluated. The two-stage anaerobic digestion has a total reactor volume of 60 L （acid reactor volume was 30 L and methane reactor volume was 30 L）. They were incubated at mesophilic and thermophilic conditions for 25 days to determine temperature profiles for the AD process. The results of the laboratory-scale experiment show that maximum biogas production occurred at 55 ℃ （38.14 L of biogas） for a period of 11 days when compared to other temperatures. Second best was at 50 ℃ （37.44 L of biogas） for a period of 12 days, followed by 40 ℃ （35.36 L of biogas） for a period of 15 days. Thermophilic temperatures will be used in further studies to examine scaling up of the process.展开更多
盐度对鱼类生态生理学作用的直接效应是引起鱼体对渗透压的调节,间接影响则表现为对鱼体与环境间物质交换与能量流动的影响(De Silva et al.,1976)。自上世纪50年代末开始,盐度一直是鱼类生理学和实验生物学的重要指标。为此,众多专家...盐度对鱼类生态生理学作用的直接效应是引起鱼体对渗透压的调节,间接影响则表现为对鱼体与环境间物质交换与能量流动的影响(De Silva et al.,1976)。自上世纪50年代末开始,盐度一直是鱼类生理学和实验生物学的重要指标。为此,众多专家就广盐性洄游种类鲑鱼生长与盐度的关系(Otto,1971;Shaw et al.,1975;MacLeod,1977;展开更多
基金Supported by Hunan Key Financial Project([2014]74)~~
文摘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.
基金supported by grants from the Na-tional Natural Science Foundation of China(No.41476127)the Science and Technology Planning Project of Zhejiang Province(No.2016F50038)+1 种基金the Science and Technology Planning Project of ZhouShan City(No.2015C31010)the Scientific Research Foundation of Zhejiang Ocean Universtiy(No.2014Q1434)
文摘An 8-week feeding trial was conducted to determine the optimal dietary protein-to-lipid ratio for juvenile Nibea albiflora with an initial weight of(11.76 ± 0.20) g.Nine experimental diets containing different concentrations of protein(40%,47%,or 54%) and lipids(5%,9%,or 13%) in a 3 × 3 factorial experimental design were tested in triplicate groups of fish,while the protein-to-energy(P/E) ratios of the diets varied in the range of 19.74–28.32 mg k J^(-1).Results showed that fish fed diets containing 9% or 13% lipids with 54% protein exhibited significantly higher weight gains and specific growth rates than those fed other diets.The feed conversion rate of fish fed the diet with 40% protein and 5% lipids was significantly poorer than that of fish fed other diets.The protein efficiency rate of fish fed diets with 5% lipids was significantly lower than that of fish fed 9% or 13% lipid diets.Carcass lipid and energy contents were positively correlated with dietary lipid level regardless of protein level.Fish fed a 54% protein diet showed the highest trypsin activity.The intestinal lipase activity of fish fed the diet containing 13% lipids was significantly higher than that of fish fed 5% or 9% lipid diets.These results demonstrate the high protein dietary requirements of N.albiflora.A diet containing 54% protein and 9%–13% lipids with a P/E ratio of 26.2–27.81 mg protein k J^(-1) can be considered optimal for juvenile N.albiflora.
文摘Food waste has developed as an alternative for the production of renewable fuels such as biogas from AD （anaerobic digestion）. In relation to the biogas production rate, digester temperature setting is one of the very important factors for digester operation, especially in low temperature countries. In this study, the effect of digester temperature on biogas and methane production efficiency in the AD of food waste was evaluated. The two-stage anaerobic digestion has a total reactor volume of 60 L （acid reactor volume was 30 L and methane reactor volume was 30 L）. They were incubated at mesophilic and thermophilic conditions for 25 days to determine temperature profiles for the AD process. The results of the laboratory-scale experiment show that maximum biogas production occurred at 55 ℃ （38.14 L of biogas） for a period of 11 days when compared to other temperatures. Second best was at 50 ℃ （37.44 L of biogas） for a period of 12 days, followed by 40 ℃ （35.36 L of biogas） for a period of 15 days. Thermophilic temperatures will be used in further studies to examine scaling up of the process.
文摘盐度对鱼类生态生理学作用的直接效应是引起鱼体对渗透压的调节,间接影响则表现为对鱼体与环境间物质交换与能量流动的影响(De Silva et al.,1976)。自上世纪50年代末开始,盐度一直是鱼类生理学和实验生物学的重要指标。为此,众多专家就广盐性洄游种类鲑鱼生长与盐度的关系(Otto,1971;Shaw et al.,1975;MacLeod,1977;
