为探明我国烟草农业碳排放特征,推进烟草农业绿色低碳体系构建,基于农户调研数据,利用农业碳足迹理论定量分析豫南烟区烟叶农户生产碳足迹,明确农户在烟草生产过程中碳排放特征,研究豫南烟区烟草生产肥料碳足迹与单位面积产值的关系,烟...为探明我国烟草农业碳排放特征,推进烟草农业绿色低碳体系构建,基于农户调研数据,利用农业碳足迹理论定量分析豫南烟区烟叶农户生产碳足迹,明确农户在烟草生产过程中碳排放特征,研究豫南烟区烟草生产肥料碳足迹与单位面积产值的关系,烟叶单位面积产量与不同功能单位碳足迹的关系。结果表明,豫南烟区烟草生产系统单位面积、单位产量、单位产值碳足迹以CO_(2)当量(CO_(2)-eq)计,分别为12 630.03 kg CO_(2)-eq·hm^(-2)、6.62 kg CO_(2)-eq·kg^(-1)、0.21 kg CO_(2)-eq·￥^(-1);烘烤用煤、烘烤用电、农膜、肥料施用是豫南烟区烟草生产碳足迹的主要来源,分别占比67.4%、14.5%、6.1%、4.0%;基于单位面积高产值,28.04%调研农户的肥料碳足迹和氮肥碳足迹过高;基于烟叶低单位面积碳足迹,20.56%农户产量过低。因此,保持烟叶产量的同时,减少生产环节碳排放是豫南烟区发展绿色烟草农业的关键,推广清洁能源烤房、肥料优化管理将成为未来豫南烟区绿色烟草生产的重要举措。展开更多
Stem cells are present in developing embryos and adult tissues of multicellular organisms. Owing to their unique features, stem cells provide excellent opportunities for experimental analyses of basic developmental pr...Stem cells are present in developing embryos and adult tissues of multicellular organisms. Owing to their unique features, stem cells provide excellent opportunities for experimental analyses of basic developmental processes such as pluripotency control and cell fate decision and for regenerative medicine by stem cell-based therapy. Stem cell cultures have been best studied in 3 vertebrate organisms. These are the mouse, human and a small laboratory fish called medaka. Specifically, medaka has given rise to the first embryonic stem (ES) cells besides the mouse, the first adult testis-derived male stem cells spermatogonia capable of test-tube sperm production, and most recently, even haploid ES cells capable of producing Holly, a semi-cloned fertile female medaka from a mosaic oocyte created by microinjecting a haploid ES cell nucleus directly into a normal oocyte. These breakthroughs make medaka a favoring vertebrate model for stem cell research, the topic of this review.展开更多
文摘为探明我国烟草农业碳排放特征,推进烟草农业绿色低碳体系构建,基于农户调研数据,利用农业碳足迹理论定量分析豫南烟区烟叶农户生产碳足迹,明确农户在烟草生产过程中碳排放特征,研究豫南烟区烟草生产肥料碳足迹与单位面积产值的关系,烟叶单位面积产量与不同功能单位碳足迹的关系。结果表明,豫南烟区烟草生产系统单位面积、单位产量、单位产值碳足迹以CO_(2)当量(CO_(2)-eq)计,分别为12 630.03 kg CO_(2)-eq·hm^(-2)、6.62 kg CO_(2)-eq·kg^(-1)、0.21 kg CO_(2)-eq·￥^(-1);烘烤用煤、烘烤用电、农膜、肥料施用是豫南烟区烟草生产碳足迹的主要来源,分别占比67.4%、14.5%、6.1%、4.0%;基于单位面积高产值,28.04%调研农户的肥料碳足迹和氮肥碳足迹过高;基于烟叶低单位面积碳足迹,20.56%农户产量过低。因此,保持烟叶产量的同时,减少生产环节碳排放是豫南烟区发展绿色烟草农业的关键,推广清洁能源烤房、肥料优化管理将成为未来豫南烟区绿色烟草生产的重要举措。
基金supported by the Biomedical Research Council of Singapore (Grant Nos. R-05-1-21-19-404, R-08-1-21-19-585 and SBIC-SSCC-002-2007)the Ministry of Education of Singapore (Grant No. R-154-000-285-112)the National University of Singapore (Grant No. R-154-000-153-720)
文摘Stem cells are present in developing embryos and adult tissues of multicellular organisms. Owing to their unique features, stem cells provide excellent opportunities for experimental analyses of basic developmental processes such as pluripotency control and cell fate decision and for regenerative medicine by stem cell-based therapy. Stem cell cultures have been best studied in 3 vertebrate organisms. These are the mouse, human and a small laboratory fish called medaka. Specifically, medaka has given rise to the first embryonic stem (ES) cells besides the mouse, the first adult testis-derived male stem cells spermatogonia capable of test-tube sperm production, and most recently, even haploid ES cells capable of producing Holly, a semi-cloned fertile female medaka from a mosaic oocyte created by microinjecting a haploid ES cell nucleus directly into a normal oocyte. These breakthroughs make medaka a favoring vertebrate model for stem cell research, the topic of this review.
