中国输日茶叶贸易及影响因素研究

本文以中日两国茶叶贸易的相关统计数据为依据,对中国输日茶叶贸易的变化进行了研究,并从日本茶叶生产和消费结构、绿色壁垒、日本茶饮料的发展及中国茶叶国际竞争力等方面对可能的影响因素进行了分析,发现中国输日茶叶贸易有进一步上升的趋势,其中绿茶和乌龙茶的输日潜力较大,同时日本茶叶生产和消费结构对中国输日茶叶贸易影响最大,从根本上决定了输日茶叶贸易必将进一步扩大,而茶饮料市场并未对输日茶叶贸易构成实质影响,日本政府的绿色壁垒及中国茶叶国际竞争力的劣势在中国输日茶叶贸易中起一定的负面影响.     

Assessing upstream invasion risk in alien freshwater fishes based on intrinsic variations in swimming speed performance

Managing the spread and impact of invasive species requires an understanding of what limits their dispersal into new areas. Here, we investigated an intrinsic component of invasive species dispersal, via assessments of the swimming speed performance of four species of alien freshwater fish at risk of invading the upper reaches of a montane river system in south‐east Australia. Using water flow measurements taken from a range of potential barriers to their upstream dispersal (fishways, culverts, natural riffle habitats), we assessed the likelihood of alien species passage based on intrinsic differences in swimming speed performance. With the four alien fish species displaying a wide range of sprint swimming speed (U_sprint) capabilities, our logistic regression analysis identified pipe culverts as being a challenge to dispersal by all but the largest individuals of one species (Rainbow trout, Oncorhynchus mykiss). Notably, fishway installations facilitating passage of the sympatric threatened species, Macquarie perch (Macquaria australasica), could allow upstream dispersal of a key threatening species (European perch, Perca fluviatilis). Our study highlights the utility of locomotor capabilities for assessing the likelihood of upstream dispersal by species following human‐assisted introductions to the lower parts of a catchment.     

Production of interspecific F1 hybrids, BC1, BC2 and BC3 populations between Lycopersicon esculentum and two accessions of Lycopersicon peruvianum carrying new root-knot nematode resistance genes

Two accessions of Lycopersicon peruvianum Mill. (PI270435, PI126443) carrying Mi-2 and Mi-3, respectively, new root-knot nematode resistance genes, were selected as the male parents for crosses with L. esculentum Mill. in order to produce interspecific hybrids. Crossability barriers between these two distantly related species were circumvented by ovule culture. A total of ten interspecific F₁ hybrid plants were produced. The hybrid nature of the putative F₁ plants was confirmed by a comparison of several morphological characteristics and a PCR-based assay. Eight of ten hybrid plants were backcrossed with L. esculentum to generate a total of 98 BC₁ progeny. Two lines were advanced to the BC₂ and BC₃ levels. Based on these results, ovule culture was found to be an effective method for the production of novel interspecific F₁ and BC₁ plants. This revised version was published online in July 2006 with corrections to the Cover Date.     

浑善达克沙地2种行距黄柳林对风速影响的研究

以浑善达克沙地东南部多伦县大骆驼场境内的黄柳灌木防风固沙沙障为研究对象,分别研究了行距为5 m和8 m的黄柳沙障对障后风速的影响.结果表明:随着高度的增加,沙障的防风效果逐渐降低,而随着风速的增大,沙障的防风效能却明显增强.行距5 m和行距8 m的沙障分别在第3排和第1排障后风速降低最显著.2种行距沙障障内的风速廓线都遵循一元线性回归.     

动物福利壁垒对中国动物及其产品与相关服务国际贸易的影响与对策建议

作者剖析了动物福利贸易壁垒成因、特征和对国际贸易的影响,指出了中国动物福利存在的问题及与发达国家的差距,评估了动物福利政策对中国动物、动物产品及相关服务出口贸易的影响。提出了构建既适合中国国情又与国际接轨的出入境动物福利保障体系的框架建议：①应积极推动中国动物福利法立法进程;②要切实提高中国动物福利保障水平;③应先行强化出入境动物福利立法;④应在进出口动物福利立法中引入企业推动模式;⑤要充分利用WTO机制应对国外动物福利壁垒;⑥要建立健全动物福利贸易壁垒预警机制;⑦要应用危害分析与关键控制点原理管理动物福利;⑧要逐步建立农场动物福利认证制度。     

渭河咸阳段非饱和层状沉积物中水分分布特征

层状结构是河流相松散沉积物中最常见的沉积结构,通常表现出一些特有的水力学性质,对水分运动过程及沉积物的持水性能产生影响.本文通过对渭河陕西咸阳段河漫滩一个层状沉积物剖面的含水率分布特征进行原位观测,讨论层状沉积物中含水率的分布特征,及其与粒度和毛细壁垒效应的关系.结果表明:在以水平层理和交错层理为主的粗细相间的层状河流沉积物中,天然含水率也呈干润相间的层状分布特征,各层含水率的大小主要与粒度成负相关;沉积物粗细相间的层状分布为毛细壁垒的形成提供条件,在降雨入渗和土壤水蒸发过程中,毛细壁垒效应对水分运动的控制会导致细粒层中含水率高于粗粒层.层状松散沉积物中水分的这种分布规律,为理解土壤持水性能提供了新的思路,对研究土壤含水率与降雨入渗、蒸发等水文过程的关系具有重要意义.     

信息化技术进步、制度变迁与洞庭湖生态经济区农业发展模式演进

农业经济增长离不开农业信息化技术进步的推动,也需要借力制度变迁。农业经济增长是动态发展过程,随着农业信息化技术进步与诱致性制度变迁持续向更高水平和更深层次演进。现阶段,洞庭湖生态经济区农业经济处于较为快速的发展状态。研究发现农业信息化技术进步与制度变迁存在偏差,需要基于农业信息化技术进步和制度变迁的耦合视角探索推进农业发展模式演进的路径。研究表明,洞庭湖生态经济区农业信息化技术进步推动传统农业向知识型农业转型、农业生产结构调整、增强农产品竞争力、改变农户生产生活方式,洞庭湖生态经济区推动了农业贷款体制变迁、农村财政体制供给的变迁,但依然存在认识农业信息化不充分、农村信息技术设施建设滞后、农业信息化技术与传统农业深度融合存在瓶颈等问题,需要继续加大农村信息化基础设施建设、推进大数据建设、强化区域信息协同治理、完善智慧农业政策体系。     

东西部农民政治冷漠比较分析——以浙江龙游县和四川东兴区农民为调查对象

通过问卷调查,对我国东西部地区农民政治冷漠的不同表现及其原因进行了比较分析:不管是不参与还是象征性参与,西部农民都表现出更大程度的冷漠;原因在于东西部农民自身利益观、文化程度和民主意识的不同,而经济是否发达和制度是否健全更是产生这种现象的主要原因。并提出了解决农民的政治冷漠问题的不同对策:对西部主要应该发展经济和进行制度建设,而对东部可以加大政治宣传力度和加强网络参与。     

Policy and institutional support for agroforestry: an analysis of two Ecuadorian case studies

Institutional and policy issues are now recognized as high priority items in agroforestry research. However, such studies based on actual field experiences seldom seem to have been undertaken. To help address this deficiency, a study was undertaken in Ecuador to evaluate institutional and policy impacts on agroforestry dissemination using two field projects as case studies.The projects were in contrasting ecological locations: the Amazonian lowlands (the Coca Agroforestry Project), and the Andean highlands (the PROMUSTA project). The impact of policy and institutional constraints (such as land tenure, research and extension support, marketing and pricing, and credit) on the implementation of these projects was assessed based on interviews with farmers and project officials as well as analyses of secondary data. The Coca project was found to be adversely impacted by the lack of extension, product marketing, and credit availability. The principal institutional constraints for the Andean project included legal obstacles to farm-land procurement, inadequate extension, little state-financial assistance, and limited affordable credit. The relevance of these issues was location specific: while access to land was not a serious constraint in the lowlands, it was a major issue in the highlands.The study validates the premise that policy and institutional evaluations should become an essential component of design and implementation of agroforestry projects. Although the components of a sound policy framework might be similar in most developing-country situations, it may not be possible to evolve universally applicable procedures for agroforestry-policy formulation because of the location-specificity of the promoted systems and the institutional issue related to their adoption.Florida Agricultural Experiment Station Journal Series No. R-03861.     

论持续农业的制度障碍与创新

发展持续农业有两个关键因素：一是技术变革，一是制度创新，而制度创新更具有决定性。笔者认为农业的外部性、弱质性、基础性构成了持续农业需要制度创新的根本原因，现行的农业土地制度、农业组织制度、农业保护制度、农村社会制度、农业发展战略已成为中国持续农业的主要制度障碍，在认真分析的基础上，提出了持续农业的制度创新路径：综合改革农业土地制度和组织制度、综合改革农业保护制度和农村社会制度、推进农业发展战略根本转变。