排序方式： 共有19条查询结果，搜索用时 15 毫秒
1.
广州市蔬菜生产布局与“渡淡”问题探讨 总被引：1，自引：1，他引：1
本文分析了广州市蔬菜供应出现淡季的主要原因，指出现行蔬菜生产布局的不合理性，并提出合理调整生产布局，改善淡季蔬菜供应的基本设想。 相似文献
2.
3.
4.
5.
王秀红 《资源与生态学报(英文版)》2016,7(4):269-274
由于蔬菜需求量的增加,中国的蔬菜产量不断增加;然而蔬菜地的化学污染会威胁到中国的食品安全。基于蔬菜和粮食作物的播种面积和产量、农业生产投入价格指数、单位面积的农业物质投入、蔬菜和粮食作物生产者价格指数和净利润等数据,本文计算分析了蔬菜地污染造成的中国潜在食品安全风险的变化趋势。研究表明,由于改革开放以来对蔬菜饮食的公共需求的不断增加和蔬菜高的市场价格,蔬菜的播种面积和产量显著增加;然而由于研究时段内蔬菜种植比例的增加,农业物质投入增加所带来的潜在污染风险也在不断增加。通过控制蔬菜地污染,中国的食品安全问题可以得到较大改善。 相似文献
6.
In this study, it was aimed to determine the effect of various aeration rates on composting to supply the optimum aeration rate for a successful and economic composting. For this aim, vegetable–fruit wastes (VFW) were composted at various aeration rates (0.37, 0.49, 0.62, 0.74, 0.86, and 0.99 L/min kg VS) and moisture, temperature, pH, electrical conductivity, C/N, and cellulose were investigated. Moistures of the reactor that had the highest aeration were generally lower than those of the others. Reactor that had the lowest aeration reached thermophilic phase earlier than the others and stayed more days. This situation was opposite for the reactor that had the highest aeration. pH variations with aeration rates were not significant. Although electrical conductivity did not differ significantly with aeration rates, at the beginning of the thermophilic phase it generally increased with the increase in aeration. The highest C/N reduction was observed in the reactor that had an aeration of 0.62 L/min kg VS. The final cellulose contents were close to each other. It could be said that aeration rates used were efficient on composting of VFW. Taking the C/N into account which is the parameter of the indicator of the stabilization in composting, it could be said that the optimum aeration rate for forced aerobic composting of VFW was 0.62 L/min kg VS. 相似文献
7.
根据水量平衡原理,采用人工模拟降雨入渗实验装置,对上海新老菜区土壤进行不同墒情状态下的多种雨强人工模拟降雨入渗试验,获取了上海菜区代表性土壤的暴雨入渗过程动态实验数据和入渗基本参数,并分析了土壤水分变化规律,可作为上海菜区开展暴雨雨涝灾情评估的依据,对类似土壤条件的长江流域平原地区菜田,也有一定的参考价值。 相似文献
8.
本文分析了造成成都市蔬菜外运损耗的原因,并利用逐步回归法建立了青芹外运损耗率与沿途气象条件之间关系的数学模型,对车厢内青芹的热负荷和需冰量进行了计算,计算结果为成都市蔬菜安全外运的车厢内需冰量及利用沿途气象条件来减少损耗提供了科学依据。 相似文献
9.
Elena Domene 《Geoforum》2007,38(2):287-298
This paper examines urban vegetable gardens in the Metropolitan Region of Barcelona (MRB) in the context of a political ecological approach. We argue that these gardens provide an interesting example of how the urbanization process creates particular “socionatures” linked in this case to retired members of the working class who occupy (often as squatters) and transform the interstices left by the expanding city in order to produce food at a small scale. We document how these vegetable gardens are the product of a peculiar form of the recent urban history of the area, and also how they are increasingly under pressure due to the rapid process of sprawl now characterizing the expansion of the built environment in the Barcelona region. Vegetable gardens also highlight the contradictions of public policies in managing urban development, since the general attitude towards their elimination from the urban landscape stands in opposition to many of the sustainability initiatives such as the “greening of cities” promoted by city councils in this area.The empirical analysis was carried out in the municipality of Terrassa, one of the largest cities in the MRB, and also one with a higher number of vegetable gardens. We interviewed 132 plot users and obtained data about the legal status of gardens, their size and appearance, and crops grown, as well as the reasons for pursuing this activity. Our results show that, in general, this is an activity undertaken by people over 60 years old, often retired members of the working class that migrated to Catalonia from other Spanish regions in the 1960s and 1970s, and that use these spaces for a variety of reasons (personal goals, support to their families, and also as a bond to their rural past). Finally, we develop some conclusions regarding vegetable gardens in which we maintain that different social classes may create different natures but that class and power relations appear to legitimize some of these natures over others, for example, private and public gardens having a much larger social and institutional appeal and support than the vegetable gardens of the retired workers. 相似文献
10.