To more accurately answer the questions “who will feed China?” and “whether Chinese people can feed themselves?”, we proposed a concept of agricultural support capacity, defined as the population that can be fed b...To more accurately answer the questions “who will feed China?” and “whether Chinese people can feed themselves?”, we proposed a concept of agricultural support capacity, defined as the population that can be fed by energy, protein and fat from food, respectively, according to nutritional intake standards. In this study, we established models to measure this, based on analysis of China’s agricultural support capacity and how this changes under self-sufficiency and open conditions, in addition to the degrees of external dependence. Our results show that, since 2007, even without foreign resources, the energy, protein, superior protein and fat obtained from domestic agriculture had been able to feed the Chinese. However, the use of foreign resources increased and strengthened China’s agricultural support capacity, in addition to improving food diversity, optimizing nutrition, assisting in the regulation of food surplus and deficiency, and providing feed for the animal breeding industry. For the past decade, China’s degree of external dependence on energy from cereals has been relatively low, however, the degrees external dependence on superior protein and fat has increased steadily at a certain rate and have been over the national food security warning level. Therefore, China still has great demand for agricultural products from other regions of the world.展开更多
This paper considers a class of ratio-dependent Holling-Taner model with infinite delay and prey harvest, which is of periodic coefficients. By means of the coincidence degree theory, a set of sufficient conditions fo...This paper considers a class of ratio-dependent Holling-Taner model with infinite delay and prey harvest, which is of periodic coefficients. By means of the coincidence degree theory, a set of sufficient conditions for the existence of at least two positive periodic solutions of this model is established.展开更多
A delayed semi-ratio-dependent predator-prey system in a periodic environment is investigated in this paper.By using a continuation theorem based on Gaines and Mawhin's coincidence degree,the global existence of p...A delayed semi-ratio-dependent predator-prey system in a periodic environment is investigated in this paper.By using a continuation theorem based on Gaines and Mawhin's coincidence degree,the global existence of positive periodic solution is studied.A set of easily verifiable sufficient conditions are obtained.展开更多
We study a non-autonomous ratio-dependent predator-prey model with exploited terms. This model is of periodic coefficients, which incorporates the periodicity of the varying environment. By means of the coincidence de...We study a non-autonomous ratio-dependent predator-prey model with exploited terms. This model is of periodic coefficients, which incorporates the periodicity of the varying environment. By means of the coincidence degree theory, we establish sufficient conditions for the existence of at least four positive periodic solutions of this model.展开更多
In order to supply better accordance for mod eling and simulation of complex networks, a new degree dependence entropy （DDE） descriptor is proposed to describe the degree dependence relationship and corre sponding c...In order to supply better accordance for mod eling and simulation of complex networks, a new degree dependence entropy （DDE） descriptor is proposed to describe the degree dependence relationship and corre sponding characteristic in this paper. First of all, degrees of vertices and the shortest path lengths between all pairs of ,ertices are computed. Then the degree dependence matrices under different shortest path lengths are con structed. At last the DDEs are extracted from the degree dependence matrices. Simulation results show that the DDE descriptor can reflect the complexity of degree dependence relationship in complex networks; high DDE indicates complex degree dependence relationship; low DDE indicates the opposite one. The DDE can be seen as a quantitative statistical characteristic, which is meaningful for networked modeling and simulation.展开更多
With k_8/k_(16), the ratio of the hydrolytic rate-constants of p-nitrophenyl octanoate (C8) to hexadecanoate (C16), as the indicator of the degree of aggregation, the linear dependence of the deg- ree of aggregation o...With k_8/k_(16), the ratio of the hydrolytic rate-constants of p-nitrophenyl octanoate (C8) to hexadecanoate (C16), as the indicator of the degree of aggregation, the linear dependence of the deg- ree of aggregation on solvent aggregating power (SAgP) has been established in five aquiorgano sol- vents, each within a certain range of volume fraction ( values) of the organic cosolvent. The mea- ning of this linearity has been discussed.展开更多
文摘To more accurately answer the questions “who will feed China?” and “whether Chinese people can feed themselves?”, we proposed a concept of agricultural support capacity, defined as the population that can be fed by energy, protein and fat from food, respectively, according to nutritional intake standards. In this study, we established models to measure this, based on analysis of China’s agricultural support capacity and how this changes under self-sufficiency and open conditions, in addition to the degrees of external dependence. Our results show that, since 2007, even without foreign resources, the energy, protein, superior protein and fat obtained from domestic agriculture had been able to feed the Chinese. However, the use of foreign resources increased and strengthened China’s agricultural support capacity, in addition to improving food diversity, optimizing nutrition, assisting in the regulation of food surplus and deficiency, and providing feed for the animal breeding industry. For the past decade, China’s degree of external dependence on energy from cereals has been relatively low, however, the degrees external dependence on superior protein and fat has increased steadily at a certain rate and have been over the national food security warning level. Therefore, China still has great demand for agricultural products from other regions of the world.
文摘This paper considers a class of ratio-dependent Holling-Taner model with infinite delay and prey harvest, which is of periodic coefficients. By means of the coincidence degree theory, a set of sufficient conditions for the existence of at least two positive periodic solutions of this model is established.
文摘A delayed semi-ratio-dependent predator-prey system in a periodic environment is investigated in this paper.By using a continuation theorem based on Gaines and Mawhin's coincidence degree,the global existence of positive periodic solution is studied.A set of easily verifiable sufficient conditions are obtained.
基金Supported by the China Postdoctoral Science Foundation (20060400267)
文摘We study a non-autonomous ratio-dependent predator-prey model with exploited terms. This model is of periodic coefficients, which incorporates the periodicity of the varying environment. By means of the coincidence degree theory, we establish sufficient conditions for the existence of at least four positive periodic solutions of this model.
基金supported by the National Natural Science Foundation of China(Grants Nos.61174156,61273189,71073172,61174035,61203140)
文摘In order to supply better accordance for mod eling and simulation of complex networks, a new degree dependence entropy （DDE） descriptor is proposed to describe the degree dependence relationship and corre sponding characteristic in this paper. First of all, degrees of vertices and the shortest path lengths between all pairs of ,ertices are computed. Then the degree dependence matrices under different shortest path lengths are con structed. At last the DDEs are extracted from the degree dependence matrices. Simulation results show that the DDE descriptor can reflect the complexity of degree dependence relationship in complex networks; high DDE indicates complex degree dependence relationship; low DDE indicates the opposite one. The DDE can be seen as a quantitative statistical characteristic, which is meaningful for networked modeling and simulation.
基金Project supported by the National Natural Science Foundation of China.
文摘With k_8/k_(16), the ratio of the hydrolytic rate-constants of p-nitrophenyl octanoate (C8) to hexadecanoate (C16), as the indicator of the degree of aggregation, the linear dependence of the deg- ree of aggregation on solvent aggregating power (SAgP) has been established in five aquiorgano sol- vents, each within a certain range of volume fraction ( values) of the organic cosolvent. The mea- ning of this linearity has been discussed.
