[Objective]This experiment was conducted on Pseudosciaena crocea to study the effects of mannan oligosaccharides on growth and antibacterial ability. [Method]1 500 experimental fishes were divided into five groups. Th...[Objective]This experiment was conducted on Pseudosciaena crocea to study the effects of mannan oligosaccharides on growth and antibacterial ability. [Method]1 500 experimental fishes were divided into five groups. The control group( C) contained no mannan oligosaccharides,the treatment groups were contained 100,200,400,800 mg /kg of konjac mannan oligosaccharides in basal diet,respectively. The experiment continued 4 months. [Result]The results showed that Konjac Mannan oligosaccharides could significantly improve weight gain Pseudosciaena crocea. Compared with control group,Test 2 group intestine protease activity increased by 45. 74%,hepatopancreatic lipase activity increased by 31. 37%,amylase activity increased by 27. 16%. Comparison with the control group,the test group serum SOD activity was significantly higher than that in the control group( P <0. 05). Lysozyme( LZM) activity,spleen and serum test group was significantly higher than that in the control group( P <0.05). Pseudosciaena crocea were infected by Anguillarum,compared with control group,the survival rate is higher than that of the control group( P <0. 05) when the dosage of 200 mg /kg,400 mg /kg. [Conclusion]According to the test results,the Konjac Mannan oligosaccharides in the basal diet suitable dosage were 200 mg /kg.展开更多
In this paper, an SEIRS epidemic model with pulse vaccination and two time delays is proposed. By using stroboscopic map and comparison principle, the disease-free periodic solution(DFPS for short) is obtained and the...In this paper, an SEIRS epidemic model with pulse vaccination and two time delays is proposed. By using stroboscopic map and comparison principle, the disease-free periodic solution(DFPS for short) is obtained and the global asymptotic stability of the DFPS is proved. The sufficient conditions for the permanence of the model are obtained. In addition, numerical simulations are done to confirm our theoretical results.展开更多
In the paper, members in farmer cooperatives are selected as investigation subjects. By using fuzzy synthetic evaluation methods, functions of farmer cooperatives, which include six functions as follows: providing tec...In the paper, members in farmer cooperatives are selected as investigation subjects. By using fuzzy synthetic evaluation methods, functions of farmer cooperatives, which include six functions as follows: providing technology and information, marketing, processing and transportation, standardized services, and credit services and rights protection, are analyzed. The quantitative analysis is conducted on the developmental status of the functions of farmer cooperatives. The evaluation results are taken as evidence to anticipate the problems in the development of farmer cooperatives and then countermeasures are put forward, including intensifying the construction of actual functions of farmer cooperatives; contracting diversified credit and loan services; improving comprehensive strength of farmer cooperatives and taking the path of combining professional and comprehensive developmental paths. This study improves our knowledge on the development of farmer cooperatives and provides new insights to solve the problems that arise following the development.展开更多
集沙铲是某款小型铁路轨道除沙车的重要工作部件。集沙铲在实际使用中受到的冲击力大、铲板刃缘变形严重,为改善集沙铲受力状况,对集沙铲集沙过程的受力状况进行研究。应用离散单元法(discrete element method,DEM)与多体动力学,分别对...集沙铲是某款小型铁路轨道除沙车的重要工作部件。集沙铲在实际使用中受到的冲击力大、铲板刃缘变形严重,为改善集沙铲受力状况,对集沙铲集沙过程的受力状况进行研究。应用离散单元法(discrete element method,DEM)与多体动力学,分别对相同工况下直板、15°板和30°板集沙铲的总受力和X、Y、Z三个方向的受力进行比较。同时,利用离散单元法对不同时刻集沙铲切分沙土瞬间的沙土颗粒的速度分布状况进行分析。最后设计并制作了集沙铲试验台,模拟了集沙铲集沙过程,并对直板和30°板集沙铲的工作转矩进行了测量。研究结果表明:增大集沙铲铲板刃缘倾角可以减小集沙铲的冲击受力;随着集沙铲铲板刃缘倾角变化,集沙铲触沙瞬间沙土颗粒的速度分布发生明显变化。研究结果对改善集沙铲冲击受力具有一定指导意义,同时也对利用离散元法研究铲板-沙土相互作用过程具有一定指导意义。展开更多
Objectives Firstly,according to the characteristics of COVID-19 epidemic and the control measures of the government of Shaanxi Province,a general population epidemic model is es-tablished.Then,the control reproduction...Objectives Firstly,according to the characteristics of COVID-19 epidemic and the control measures of the government of Shaanxi Province,a general population epidemic model is es-tablished.Then,the control reproduction number of general population epidemic model is obtained.Based on the epidemic model of general population,the epidemic model of general population and college population is further established,and the control reproduction number is also obtained.Methods For the established epidemic model,firstly,the expression of the control reproduc-tion number is obtained by using the next generation matrix.Secondly,the real-time reported data of COVID-19 in Shaanxi Province is used to fit the epidemic model,and the parameters in the model are estimated by least square method and MCMC.Thirdly,the Latin hypercube sampling method and partial rank correlation coefficient(PRCC)are adopted to analyze the sensitivity of the model.Conclusions The control reproduction number remained at 3 from January 23 to January 31,then gradually decreased from 3 to slightly greater than 0.2 by using the real-time reports on the number of COVID-19 infected cases from Health Committee of Shaanxi Province in China.In order to further control the spread of the epidemic,the following measures can be taken:(i)reducing infection by wearing masks,paying attention to personal hygiene and limiting travel;(i)improving isolation of suspected patients and treatment of symptomatic individuals.In particular,the epidemic model of the collge population and the general population is estab-lished,and the control reproduction number is given,which will provide theoretical basis for the prevention and control of the epidemic in the colleges.展开更多
In this paper, we propose an SIRS epidemic model with pulse vaccination, birth pulse and Logistic death rate. By using the stroboscopic map of a discrete dynamical system, the disease-free periodic solution (DFPS for ...In this paper, we propose an SIRS epidemic model with pulse vaccination, birth pulse and Logistic death rate. By using the stroboscopic map of a discrete dynamical system, the disease-free periodic solution (DFPS for short) of the model under pulse vaccination and birth pulse is obtained. Based on the Floquet theory and comparison theorem of impulsive differential equations, the global asymptotic stability of the DFPS is given, and sufficient conditions for the permanence of the model are obtained. In addition, numerical simulations are done to confirm our theoretical results.展开更多
The strategy of rural revitalization puts ecology and economic development at the same level,in order to explore whether the eco-efficiency compensation policy for public welfare forests can achieve a“win-win”for bo...The strategy of rural revitalization puts ecology and economic development at the same level,in order to explore whether the eco-efficiency compensation policy for public welfare forests can achieve a“win-win”for both ecology and people livelihood.This study probed into the consideration of income structure and used OLS analysis to conduct an empirical analysis on a sample of 443 households in Shaanxi Province.It was found that the eco-efficiency compensation for public welfare forests had not only a significantly positive effect on the forestry income and the total income of farm households,but also had a constructive influence on the non-forestry income,though smaller and less significant,which was closely attributed to the original income structures of these farm households.In addition,personal and household characteristics such as age,educational level and labor force size played decisive roles to nonforestry income and total income of farm households as well.展开更多
基金Funded by Key Project of Shanghai Science and Technology Committee(10 jc140620011320501200)
文摘[Objective]This experiment was conducted on Pseudosciaena crocea to study the effects of mannan oligosaccharides on growth and antibacterial ability. [Method]1 500 experimental fishes were divided into five groups. The control group( C) contained no mannan oligosaccharides,the treatment groups were contained 100,200,400,800 mg /kg of konjac mannan oligosaccharides in basal diet,respectively. The experiment continued 4 months. [Result]The results showed that Konjac Mannan oligosaccharides could significantly improve weight gain Pseudosciaena crocea. Compared with control group,Test 2 group intestine protease activity increased by 45. 74%,hepatopancreatic lipase activity increased by 31. 37%,amylase activity increased by 27. 16%. Comparison with the control group,the test group serum SOD activity was significantly higher than that in the control group( P <0. 05). Lysozyme( LZM) activity,spleen and serum test group was significantly higher than that in the control group( P <0.05). Pseudosciaena crocea were infected by Anguillarum,compared with control group,the survival rate is higher than that of the control group( P <0. 05) when the dosage of 200 mg /kg,400 mg /kg. [Conclusion]According to the test results,the Konjac Mannan oligosaccharides in the basal diet suitable dosage were 200 mg /kg.
基金The Natural Science Basic Research Plan in Shaanxi Province of China(2018JM1011)Natural Science Basic Research Plan in Shaanxi Province of China(2017JQ1014)NSF of China(11701041)
文摘In this paper, an SEIRS epidemic model with pulse vaccination and two time delays is proposed. By using stroboscopic map and comparison principle, the disease-free periodic solution(DFPS for short) is obtained and the global asymptotic stability of the DFPS is proved. The sufficient conditions for the permanence of the model are obtained. In addition, numerical simulations are done to confirm our theoretical results.
基金Supported by Humanities and Social Sciences Fund of Ministry of Education (2010-2012,09YJA790165)
文摘In the paper, members in farmer cooperatives are selected as investigation subjects. By using fuzzy synthetic evaluation methods, functions of farmer cooperatives, which include six functions as follows: providing technology and information, marketing, processing and transportation, standardized services, and credit services and rights protection, are analyzed. The quantitative analysis is conducted on the developmental status of the functions of farmer cooperatives. The evaluation results are taken as evidence to anticipate the problems in the development of farmer cooperatives and then countermeasures are put forward, including intensifying the construction of actual functions of farmer cooperatives; contracting diversified credit and loan services; improving comprehensive strength of farmer cooperatives and taking the path of combining professional and comprehensive developmental paths. This study improves our knowledge on the development of farmer cooperatives and provides new insights to solve the problems that arise following the development.
文摘集沙铲是某款小型铁路轨道除沙车的重要工作部件。集沙铲在实际使用中受到的冲击力大、铲板刃缘变形严重,为改善集沙铲受力状况,对集沙铲集沙过程的受力状况进行研究。应用离散单元法(discrete element method,DEM)与多体动力学,分别对相同工况下直板、15°板和30°板集沙铲的总受力和X、Y、Z三个方向的受力进行比较。同时,利用离散单元法对不同时刻集沙铲切分沙土瞬间的沙土颗粒的速度分布状况进行分析。最后设计并制作了集沙铲试验台,模拟了集沙铲集沙过程,并对直板和30°板集沙铲的工作转矩进行了测量。研究结果表明:增大集沙铲铲板刃缘倾角可以减小集沙铲的冲击受力;随着集沙铲铲板刃缘倾角变化,集沙铲触沙瞬间沙土颗粒的速度分布发生明显变化。研究结果对改善集沙铲冲击受力具有一定指导意义,同时也对利用离散元法研究铲板-沙土相互作用过程具有一定指导意义。
基金Supported by the Fundamental Research Funds for the Central Universities,CHD(300102129201)the Nat ural Science Basic Research Plan in Shaanxi Province of China(2018JM1011)the National Natural Science Foundation of China(11701041)。
文摘Objectives Firstly,according to the characteristics of COVID-19 epidemic and the control measures of the government of Shaanxi Province,a general population epidemic model is es-tablished.Then,the control reproduction number of general population epidemic model is obtained.Based on the epidemic model of general population,the epidemic model of general population and college population is further established,and the control reproduction number is also obtained.Methods For the established epidemic model,firstly,the expression of the control reproduc-tion number is obtained by using the next generation matrix.Secondly,the real-time reported data of COVID-19 in Shaanxi Province is used to fit the epidemic model,and the parameters in the model are estimated by least square method and MCMC.Thirdly,the Latin hypercube sampling method and partial rank correlation coefficient(PRCC)are adopted to analyze the sensitivity of the model.Conclusions The control reproduction number remained at 3 from January 23 to January 31,then gradually decreased from 3 to slightly greater than 0.2 by using the real-time reports on the number of COVID-19 infected cases from Health Committee of Shaanxi Province in China.In order to further control the spread of the epidemic,the following measures can be taken:(i)reducing infection by wearing masks,paying attention to personal hygiene and limiting travel;(i)improving isolation of suspected patients and treatment of symptomatic individuals.In particular,the epidemic model of the collge population and the general population is estab-lished,and the control reproduction number is given,which will provide theoretical basis for the prevention and control of the epidemic in the colleges.
基金The Fundamental Research Funds for the Central Universities,CHD (300102129202)the NSF (11701041) of China+1 种基金the Natural Science Basic Research Plan (2018JM1011) in Shaanxi Province of ChinaScientific Innovation Practice Project (300103002110) of Postgraduates of Chang’an University
文摘In this paper, we propose an SIRS epidemic model with pulse vaccination, birth pulse and Logistic death rate. By using the stroboscopic map of a discrete dynamical system, the disease-free periodic solution (DFPS for short) of the model under pulse vaccination and birth pulse is obtained. Based on the Floquet theory and comparison theorem of impulsive differential equations, the global asymptotic stability of the DFPS is given, and sufficient conditions for the permanence of the model are obtained. In addition, numerical simulations are done to confirm our theoretical results.
基金supported by the Key Research Project of State Forestry and Grassland Administration“Research on Collective Forest Development Strategy in the Context of Implementing Rural Revitalization Strategy”(Grant No.LGS-2018-012)
文摘The strategy of rural revitalization puts ecology and economic development at the same level,in order to explore whether the eco-efficiency compensation policy for public welfare forests can achieve a“win-win”for both ecology and people livelihood.This study probed into the consideration of income structure and used OLS analysis to conduct an empirical analysis on a sample of 443 households in Shaanxi Province.It was found that the eco-efficiency compensation for public welfare forests had not only a significantly positive effect on the forestry income and the total income of farm households,but also had a constructive influence on the non-forestry income,though smaller and less significant,which was closely attributed to the original income structures of these farm households.In addition,personal and household characteristics such as age,educational level and labor force size played decisive roles to nonforestry income and total income of farm households as well.
