Establishment of farmers' professional cooperatives is an effective approach of settling conflicts between small-scale production of rural households and great market, however, there are still many problems such a...Establishment of farmers' professional cooperatives is an effective approach of settling conflicts between small-scale production of rural households and great market, however, there are still many problems such as low level of standardization, unscientific market positioning, poor capacity of mitigating risks, and unfavorable ecological benefits. This study, based on field investigation data and successful support experience, further explored operation and management problems existing in Jilin Farming Cooperative, and proposed pertinent solutions so as to enhance the high-efficiency and standard operation of farmers' professional cooperatives in Jilin Province and even China.展开更多
基金Supported by National Natural Science Foundation of China(92064014,11933006)Science and Technology Commission of Shanghai Municipality(18J1414900)Youth Innovation Promotion Association CAS。
基金Supported by Research on Scientific Renovation and Sustainable Economic Development (Program of Humanities and Social Science Foundation of the Ministry of Education,09YJA790080)Systematic Analysis of Agricultural Scientific and Technological Progress in Jilin Province (the "Eleventh Five-year" Research Program of Social Science of Jilin Department of Education)Operation Design of Farmers'Professional Cooperatives in Gongzhuling City (Undergraduates' Inno-vative Experiment Program of Jilin University,2010C83280)
文摘Establishment of farmers' professional cooperatives is an effective approach of settling conflicts between small-scale production of rural households and great market, however, there are still many problems such as low level of standardization, unscientific market positioning, poor capacity of mitigating risks, and unfavorable ecological benefits. This study, based on field investigation data and successful support experience, further explored operation and management problems existing in Jilin Farming Cooperative, and proposed pertinent solutions so as to enhance the high-efficiency and standard operation of farmers' professional cooperatives in Jilin Province and even China.
文摘目的制备小豆蔻明纳米混悬剂(cardamonin nanosuspensions,Car-NPs),研究其体外抗肿瘤活性。方法采用反溶剂沉淀联合高压均质法制备Car-NPs,以平均粒径及多分散指数(polydispersity index,PDI)为评价指标,对药载比、均质压力、均质次数进行单因素考察,利用Box-Behnken效应面设计法优化处方工艺;对最优处方工艺制备的Car-NPs进行表征,以动态光散射法测定平均粒径、粒度分布和ζ电位,在不同生理介质中监测粒径变化考察介质稳定性,透析法考察载药纳米粒的体外药物释放;通过细胞计数试剂盒-8(CCK-8)法测定并评估小豆蔻明游离药物及Car-NPs对人肝癌HepG2细胞、小鼠乳腺癌4T1细胞的体外细胞毒性。结果选用P188为稳定剂制备Car-NPs,最佳工艺处方为药载比4∶1,均质压力为65.37 MPa,均质次数11次;所制备的Car-NPs平均粒径为(198.5±5.4)nm,PDI为0.191±0.020,载药量为(62.54±0.13)%,包封率为(95.65±0.26)%,透射电子显微镜(TEM)下呈均一的圆球状;Car-NPs在PBS、5%葡萄糖、生理盐水、人工胃肠液中都能够稳定存在,满足口服和iv给药要求;以0.1%聚乙烯吡咯烷酮(PVP)为保护剂,Car-NPs冻干复溶后粒径基本不变,便于长期保存;Car-NPs在磷酸盐缓冲液中,呈现出先速释后缓释的两相释放曲线,释药过程符合一级释放方程,Q=1-e^−0.1048 t+73.586),R^(2)=0.9903。在168 h内累积释放率达到76.49%,而相同条件下小豆蔻明物理混悬液的累积释放率仅有22.65%;Car-NPs显著提高了小豆蔻明对4T1细胞[半数抑制浓度(IC_(50)),113.2μg/mL vs 33.89μg/mL,P<0.001]和HepG2细胞的杀伤作用(IC_(50),126.4μg/mL vs 52.94μg/mL,P<0.001)。结论采用Box-Behnken效应面法优化了Car-NPs的处方和工艺,所制备的Car-NPs有效解决了小豆蔻明难溶、难给药问题,冻干后便于长期保存。Car-NPs提高了小豆蔻明的体外释放度和对肿瘤细胞的杀伤作用,口服有望提高生物利用度;基于滞留效应(enhanced permeability and retention effect,EPR),iv给药有望提高药物在肿瘤组织中的分布。
