Driven by urbanization and industrialization,arable land in hilly and mountainous regions of China is gradually becoming marginalized,with the extent of arable land abandonment rapidly expanding from poor-quality slop...Driven by urbanization and industrialization,arable land in hilly and mountainous regions of China is gradually becoming marginalized,with the extent of arable land abandonment rapidly expanding from poor-quality sloping arable land to high-quality terraces.The abandonment of large-scale terraces will lead to a series of socio-economic and ecological effects.A national sample survey was used to investigate the extent and spatial distribution of terrace abandonment in China,and a total of 560 valid village questionnaires from 329 counties were collected in the mountainous areas of China.The main findings are as follows:(1)The phenomenon of terrace abandonment was widespread throughout the country,with 54% of the total surveyed villages exhibiting terrace abandonment,and the area of abandoned terraces accounting for 9.79% of the total.(2) The degree of terrace abandonment is high in the south and low in the north.The most serious region with abandonment was the hilly and mountainous areas in the south,especially in the middle and lower Yangtze River region.(3)The main driving factors of terrace abandonment were rural labor migration,agricultural mechanization level,irrigation conditions,and transportation conditions for cultivation.Targeted measures should be taken based on the specific conditions of each area to alleviate terrace abandonment.Measures such as improving terrace mechanization are universally applicable.Specifically,low-quality terraces can be withdrawn orderly,and for high-quality terraces,multiple measures are needed to consolidate agricultural production,such as adjusting the planting structure,strengthening agricultural infrastructure construction,and encouraging the transfer of land-use rights as well as large-scale operation.展开更多
背景:纳米材料是抗肿瘤药物的理想载体,具有重要的科学价值和应用价值,为临床抗肿瘤提供了新的有效手段。目的:系统评价纳米给药系统在肿瘤靶向治疗的基础研究及临床应用。方法:以"nanoparticle,cancer,drug delivery system,nanot...背景:纳米材料是抗肿瘤药物的理想载体,具有重要的科学价值和应用价值,为临床抗肿瘤提供了新的有效手段。目的:系统评价纳米给药系统在肿瘤靶向治疗的基础研究及临床应用。方法:以"nanoparticle,cancer,drug delivery system,nanotube,nanosphere"为关键词,计算机检索北美临床试验注册中心及Web of Science数据库2000-01-01/2012-12-31发表的纳米给药系统在肿瘤靶向治疗相关临床试验注册项目及文献。根据纳入与排除标准筛选文献,将检索结果以注册号、注册题目、项目状态、干预措施、试验的申办者、试验的疾病种类导出进行评价质量及文献分析。结果与结论:①北美临床试验注册中心关于纳米给药系统在肿瘤靶向治疗的相关临床试验研究开始于1999年,共检索到注册项目489项,经查阅后,共有429项纳入了分析。美国注册的纳米载体肿瘤靶向给药临床试验项目最多,共112项,其次为加拿大24项。中国注册的临床试验有22项,其中大陆注册8项,香港地区注册4项,台湾地区注册10项。研究的注册数量2003年跌至谷底,只有5项注册项目,之后数量大幅度升高,在2008年注册项目数量达到顶峰,为56项。2008年后,注册的项目数量处于波动状态。②北美临床试验注册中心纳米给药系统在肿瘤靶向治疗的相关临床试验项目样本量在1-2000之间,以50人以下的小样本研究为主。研究的肿瘤类型以乳腺癌为主,其次为内分泌腺瘤及淋巴瘤。③2000-01-01/2012-12-31在Web of Science数据库发表的纳米载体肿瘤靶向给药相关文章4497篇,其中,美国发文量占总数比重最大(66.42%),发表文章2987篇。高被引文章主要发表在Proceedings of the National Academy of Sciences of the United States of America(《美国科学院院刊》)。展开更多
基金Key Program of National Natural Science Foundation of China,No.41930757GDAS’ Project of Science and Technology Development,No.2020GDASYL-20200104005。
文摘Driven by urbanization and industrialization,arable land in hilly and mountainous regions of China is gradually becoming marginalized,with the extent of arable land abandonment rapidly expanding from poor-quality sloping arable land to high-quality terraces.The abandonment of large-scale terraces will lead to a series of socio-economic and ecological effects.A national sample survey was used to investigate the extent and spatial distribution of terrace abandonment in China,and a total of 560 valid village questionnaires from 329 counties were collected in the mountainous areas of China.The main findings are as follows:(1)The phenomenon of terrace abandonment was widespread throughout the country,with 54% of the total surveyed villages exhibiting terrace abandonment,and the area of abandoned terraces accounting for 9.79% of the total.(2) The degree of terrace abandonment is high in the south and low in the north.The most serious region with abandonment was the hilly and mountainous areas in the south,especially in the middle and lower Yangtze River region.(3)The main driving factors of terrace abandonment were rural labor migration,agricultural mechanization level,irrigation conditions,and transportation conditions for cultivation.Targeted measures should be taken based on the specific conditions of each area to alleviate terrace abandonment.Measures such as improving terrace mechanization are universally applicable.Specifically,low-quality terraces can be withdrawn orderly,and for high-quality terraces,multiple measures are needed to consolidate agricultural production,such as adjusting the planting structure,strengthening agricultural infrastructure construction,and encouraging the transfer of land-use rights as well as large-scale operation.
文摘背景:纳米材料是抗肿瘤药物的理想载体,具有重要的科学价值和应用价值,为临床抗肿瘤提供了新的有效手段。目的:系统评价纳米给药系统在肿瘤靶向治疗的基础研究及临床应用。方法:以"nanoparticle,cancer,drug delivery system,nanotube,nanosphere"为关键词,计算机检索北美临床试验注册中心及Web of Science数据库2000-01-01/2012-12-31发表的纳米给药系统在肿瘤靶向治疗相关临床试验注册项目及文献。根据纳入与排除标准筛选文献,将检索结果以注册号、注册题目、项目状态、干预措施、试验的申办者、试验的疾病种类导出进行评价质量及文献分析。结果与结论:①北美临床试验注册中心关于纳米给药系统在肿瘤靶向治疗的相关临床试验研究开始于1999年,共检索到注册项目489项,经查阅后,共有429项纳入了分析。美国注册的纳米载体肿瘤靶向给药临床试验项目最多,共112项,其次为加拿大24项。中国注册的临床试验有22项,其中大陆注册8项,香港地区注册4项,台湾地区注册10项。研究的注册数量2003年跌至谷底,只有5项注册项目,之后数量大幅度升高,在2008年注册项目数量达到顶峰,为56项。2008年后,注册的项目数量处于波动状态。②北美临床试验注册中心纳米给药系统在肿瘤靶向治疗的相关临床试验项目样本量在1-2000之间,以50人以下的小样本研究为主。研究的肿瘤类型以乳腺癌为主,其次为内分泌腺瘤及淋巴瘤。③2000-01-01/2012-12-31在Web of Science数据库发表的纳米载体肿瘤靶向给药相关文章4497篇,其中,美国发文量占总数比重最大(66.42%),发表文章2987篇。高被引文章主要发表在Proceedings of the National Academy of Sciences of the United States of America(《美国科学院院刊》)。
