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One size fits all? Contract farming among broiler producers in China

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Journal of Integrative Agriculture 2018年第2期17卷 473-482页

作者： HUANG Ze-ying XU Ying ZENG Di wang Chen wang ji-min Institute of Agricultural Economics and Development Chinese Academy of Agricultural Sciences Centre for Global Food and Resources University of Adelaide

Contract farming has been increasingly found to benefit smallholders in developing countries, yet much less is known about its role in the poultry industry where economies of scale could be more prominent. This study aims to narrow this gap by analysing the choice of contract farming among Chinese broiler producers using a nationally representative survey. Simply cost-benefit analysis and multinomial logit regression modelling are jointly employed to explain contract farming decision making especially among small producers. In contrast to many recent studies, we find that small producers, though not passively excluded, usually opt out of contract farming due to limited profitability when large producers are coexistent. Such relationship is appropriately identified through a control function approach to correct for possible endogeneity. Therefore, contract farming may not help achieve higher welfare goals for small broiler producers who actually instead seek alternative market opportunities that better realise their comparative advantages.

关键词： contract farming broiler price multinomial logit China

Detection of H_2O_2 at a composite film modified electrode with highly dispersed Ag nanoparticles in Nafion

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Chinese Chemical Letters 2011年第4期22卷 458-460页

作者： Mei Xiu Kan Xue ji wang Hui min Zhang School of Science Beijing Institute of TechnologyBeijing 100081China

Ag nanoparticles were prepared by using the ion-exchange of Nafion combined with electrochemical reduction on the electrode. Ag nanoparticles are highly dispersed in Nafion film with an average size of 4.0±0.2 *** amount of Ag nanoparticles can be readily controlled by the amount of Nafion coated on the *** obtained Ag nanoparticles exhibit good catalytic activity for the reduction of H2O2 with a linear response to H2O2 in the concentration range of 0.04-8.0 mmol/L with a sensitivity of 0.34μA/mmol/L and a detection limit of 1.0×10^（-8） mol/L.

关键词： Ag nanoparticles Nafion Electrodeposition Electrocatalytic activity Hydrogen peroxide

Exciton-Dependent Pre-formation Probability of Composite Particles

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Communications in Theoretical Physics 2007年第6期47卷 1106-1110页

作者： ZHANG jing-Shang wang ji-min DUAN Jun-Feng China Institute of Atomic Energy P.O. Box 275（41） Beijing 102413 China

In Iwamoto-Harada model the whole phase space is full of fermions. When the momentum distributions of the exciton states are taken into account, the pre-formation probability of light composite particles could be improved, and the exciton state-dependent pre-formation probability has been proposed. The calculated results indicate that the consideration of the momentum distribution enhances the pre-formation probability of [1, m] configuration, and suppresses that of [ι 〉 1, m] configurations seriously.

关键词： pre-formation probability pre-equilibrium emission

Adoption of HPAI biosecurity measures： The Chinese broiler industry

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Journal of Integrative Agriculture 2017年第1期16卷 181-189页

作者： HUANG Ze-ying Adam Loch Christopher Findlay wang ji-min Institute of Agricultural Economics and Development Chinese Academy of Agricultural Sciences Beijing 100081 P.R.China Centre for Global Food and Resources University of Adelaide Adelaide 5005 South Australia Faculty of the Professions University of Adelaide Adelaide 5005 South Australia

Highly pathogenic avian influenza （HPAI） contamination via wild birds and rodents poses a threat to food security and safety. As chicken meat comprises an increasing proportion of diet in China, it is useful to determine whether broiler farmers are adopting wild bird and rodent controls to minimize the risk of HPAI impacts on food supply. Our study surveyed a cross sectional sample of 331 Chinese broiler farmers in six provinces. We find that only 47% of farmers （mainly farmers with large herds） adopted control measures against wild birds and rodents, while 14% adopted no measures. Farm size was the biggest driver of adoption followed by proportion of farm revenue derived from broiler production. However, southern farmers were at a far greater probability of non-adoption. We suggest that assistance in the form of education/training programs and subsidized traps or baiting controls across smaller producers could help raise of the adoption level toward more effective HPAI control.

关键词： highly pathogenic avian influenza broiler farmers livestock disease biosecurity adoption

Analysis of Neutron Double-Differential Cross Sections for n ＋ ^12 C Reaction Below 30 MeV

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Communications in Theoretical Physics 2007年第3X期48卷 534-540页

作者： SUN Xiao-Jun DUAN Jun-Feng wang ji-min ZItANG jing-Shang College of Physics and Electronic Engineering Guangxi Normal University~ Guilin 541004 China China Institute of Atomic Energy P.O. Box 275(41) Beijing 102413 China

Based on the light nucleus reaction model （Nucl. Sci. Eng. 133 （1999） 218）, four aspects （neutron incident energy region, reaction channel analysis, the renewed level schemes and the optical model parameters） of n＋ ^12 C reaction are improved to calculate total outgoing neutron double-dilferential cross sections with modified LUNF code below 30 MeV. The calculated results agree fairly well with the experimental data at En = 14.1 MeV and 18 MeV. The analysis shows that the pre-equilibrium mechanism, which is exactly considered the conservation of energy, momentum and parity, dominates the whole reaction process. The contribution of the neutron emission from 5He to total energy- angular spectra is also considered properly. This modified LUNF code will be a useful tool to set up the file of neutron double-differential crass sections below 30 Me V in the neutron evaluation nuclear data library.

关键词： double-differential cross section pre-equilibrium emission ^5He emission

The puzzle of the missing meat: Food away from home and China's meat statistics

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Journal of Integrative Agriculture 2015年第6期14卷 1033-1044页

作者： XIAO Hong-bo CHEN Qiong wang ji-min Les Oxley MA Heng-yun School of Economics and Management Beijing University of Agriculture Institute of Rural Economy and Agricultural Regional Planning Tianjin Academy of Agricultural Sciences Institute of Agricultural Economics and Development Chinese Academy of Agricultural Sciences Department of Economics University of Waikato College of Economics and Management Henan Agricultural University

From 1985, an increasing gap has emerged between the official statistical measures of meat production and meat consumption in China, which has raised concerns from many researchers using such data. In this paper we report the results of 428 observations（survey of 107 urban and rural households×4 quarters） from 7 provinces conducted in 2010, and compare them with the official statistical data from the National Bureau of Statistics of China（NBSC）. We conclude that the main reason for the discrepancy is due to the underreporting of consumption, which is due mainly to the omission of consumption away from home.

关键词： consumed quarters capita official household income missing puzzle Bureau raised

Further Analysis of Neutron Double-Differential Cross Section of n ＋ ^16O at 14.1 MeV and 18 MeV

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Communications in Theoretical Physics 2005年第4X期44卷 701-706页

作者： DUAN Jun-Feng YAN Yu-Liang wang ji-min SUN Xiao-Jun ZHANG jing-Shang China Institute of Atomic Energy P.O. Box 275(41) Beijing 102413 China College of Physics and Information Technology Guangxi Normal University Guilin 541004 China

By using a new reaction model for light nuclei, the double-differential cross section of total outgoing neutron with LUNF code for n＋^16O reactions at En=14.1 MeV and 18 MeV have been calculated and analyzed. In this paper the opened reaction channels, which have contribution to emitting the neutrons, are listed in detail. To improve the fitting results the direct inelastic scattering mechanism is involved. The calculating results agree fairly well with the experimental data at E,~ = 14.1 MeV and the deviation from calculated results and experimental data in low energy region at En= 18 MeV has been analyzed. Since the possibility of 5He has been affirmed theoretically [J.S. Zhang, Sci. Chin. G 47 （2004） 137], so 5He emission from n＋ ^16O reaction is taken into account, which plays an important role at the region of the outgoing neutron energy εn〈3 MeV in total outgoing neutron energy-angular spectrum. The calculated results indicate that the pre-equilibrium mechanism dominates the whole reaction processes, and the recoil effect in light nuclear reactions is essentially important.

关键词： total outgoing neutron energy-angular spectrum light nucleus reaction

^5He Emission in Neutron-Induced ^10B Reactions

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Communications in Theoretical Physics 2006年第3X期46卷 527-532页

作者： wang ji-min DUAN Jun-Feng YAN Yu-Liang SUN Xiao-Jun ZHANG jing-Shang China Institute of Atomic Energy P.O. Box 275(41) Beijing 102413 China College of Physics and Electronic Engineering Guangxi Normal University Guilin 541004 China

In n ＋^10B reactions, ^5He cluster emission has been discussed with the updated level scheme and the new optical model parameters. In this paper the reaction channels related to ^5He emission are listed in detail. By using the new reaction model for light nuclei, the double-differential cross sections of total outgoing neutrons for n ＋ ^10 B reactions at En= 14.2 MeV have been calculated, and the results agree fairly well with the measurements. Particularly, in the energy-angular spectra the contribution from the 5He-emission to the total outgoing neutron double-differential cross sections has also been analyzed, and the partial energy-angular spectra of 60° at En= 14.2 MeV have been given. The calculated results indicate that once the 5He emission is taken into account, the fitting with the double-differential measurements of total outgoing neutrons at the low energy region could be improved. Therefore, to consider the ^5He emission properly in the reaction processes of light nuclei is necessary.

关键词： ^ 5He emission double-differential cross section pre-equilibrium emission

Voltage-Induced Effect on Resistance of C:N/Si Heterojunctions

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Chinese Physics Letters 2012年第2期29卷 178-181页

作者： GAO Xi-Li ZHANG Xiao-Zhong WAN Cai-Hua wang ji-min Laboratory of Advanced Materials Department of Materials Science and EngineeringTsinghua UniversityBeijing 100084 National Center for Electron Microscopy(Beijing) Tsinghua UniversityBeijing 100084

Nitrogen doped a-C/Silicon (a-C:N/Si) heterojunctions have been fabricated by using the pulsed laser deposition (PLD) technique and their current-voltage characteristics at various temperatures are *** reverse applied voltages,a-C:N/Si heterojunctions exhibit metal-insulator transition characteristics and the transition temperature can be controlled by the applied *** the excitation of repeated high reverse applied voltages,the current-voltage curves show obvious hysteresis behaviors at low *** hysteresis behaviors are reproducible and the ratio of the high/low resistance can be greater than 104.

关键词： hysteresis C:N Voltage