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1.
稻鳅共生种养模式试验研究 总被引:2,自引:0,他引:2
[目的]稻鳅共生是典型的稻田综合利用模式,符合生态农业发展方向。通过对稻鳅共生生态系统的生理生态学机制开展试验研究,为进一步推广稻鳅共生种养模式提供科学依据。[方法]采用田间试验方法,以水稻单作为对照,研究了不同泥鳅养殖密度下的稻鳅共生对水稻农艺性状、土壤理化性质、水稻产量构成的影响,并对稻鳅共生种养模式进行了经济效益分析。[结果]与对照处理相比,水稻长势在株高、有效分蘖率、根长等方面有一定提高。养殖田水稻株高增高了3%,有效分蘖率提高了8%~11%,根长提高了8.8%~31.3%。在土壤理化性质方面,与对照相比,土壤容重降低了7.1%~21.2%,孔隙度增加了4.1%~14.7%。实验前后养殖田内土壤有机质增加了3.5%~26.5%,对照田降低了2.5%~5.8%。土壤肥力(氮、磷、钾)减少,但减少幅度小于对照处理。稻鳅共生种养模式下水稻产量提高了5%~25%,同时稻田增收泥鳅1 725~3 375kg/hm2,净收入为1.836 0万~2.307 0万元/hm2,经济效益提高了3.65~4.84倍。稻鳅共生种养模式中泥鳅的养殖密度为30万尾/hm2时稻田的生态效益和经济效益最佳。[结论]稻鳅共生有效改善了土壤理化性质,促进了水稻的生长,提高了稻田产量和产值。 相似文献
2.
重庆市城市土地经济效益评价 总被引:5,自引:0,他引:5
从产出和投入两方面构建城市土地经济效益评价的指标体系,采用层次分析法对重庆城市土地的经济效益进行评价,可知:重庆城市土地的经济效益总体水平较低、波动较大,重庆城市近年来投入偏高影响了土地经济效益,而且重庆城市土地利用的集约化水平不高. 相似文献
3.
Summary Competition authorities are increasingly measuring the effects of their enforcement actions, seeking a robust justification
for the proliferation of competition policy. We highlight the importance of identifying the right counterfactual against which
to measure effects, and set out the relevant categories of costs and benefits. We then explore how a balance can be struck
between the benefits and inherent limitations of these measurement exercises. Relatively crude analyses of cartel action benefits
can be sufficient to achieve public legitimacy for competition policy. Assessing the effects of merger and conduct inquiries
is often ambiguous, but could be used to improve decision-making processes.
Director and Managing Consultant, respectively, at Oxera, Oxford and London. The valuable comments of Fod Barnes, Kerry Hughes
and an anonymous referee are gratefully acknowledged. The opinions expressed in this article are those of the authors alone. 相似文献
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Dong He Laurent L. Pauwels 《中国与世界经济(英文版)》2008,16(6):1-21
In the present paper, we model the policy stance of the People's Bank of China (PBC) as a latent variable, and the discrete changes in the reserve requirement ratio, policy interest rates, and the scale of open market operations are taken as signals of movement of this latent variable. We run a discrete choice regression that relates these observed indicators of policy stance to major trends of macroeconomic and financial developments, which are represented by common factors extracted from a large number of variables. The predicted value of the estimated model can then be interpreted as the implicit policy stance of the PBC. In a second step, we estimate how much of the variation in the PBC' s implicit stance can be explained by measures of its policy objectives on inflation, growth and financial stability. We find that deviations of CPI inflation from an implicit target and deviations of broad money growth from the announced targets, but not output gaps, figure significantly in the PBC's policy changes. 相似文献
8.
B. Mertens R. Poccard-Chapuis M.-G. Piketty A.-E. Lacques A. Venturieri 《Agricultural Economics》2002,27(3):269-294
The Amazon is the largest tropical forest area on Earth, and has been undergoing rapid deforestation for the last four decades. In the Brazilian Amazon, large‐scale pasture for cattle ranching and soybean production are the main land uses, leading to a yearly deforestation rate of 0.5%. These conversions are mostly located in frontier areas distributed along the so‐called “arc of deforestation”. Within this large zone, various land use change processes are interacting through several modes of land valuation and organisation. From several case studies in the State of Pará (Brazil), the current project aims at analysing how landscape dynamics are related to infrastructure development, ecological conditions, zoning policies and to the evolution and the organisation of the production, consumption and marketing chains of livestock products. This paper presents the results for one test site, the region of São Félix do Xingú, South of Pará This region is the focus of land speculation, cattle expansion, and deforestation. Road construction, investments in electrical energy, financial credit for cattle, and the land reform policies have all fuelled this process. All these factors make this region one of the most dynamic agricultural frontiers in the Brazilian Amazon. The main objective of the paper is to improve our understanding of deforestation processes by crossing spatial analyses and 1ivestock economics.studies, and to characterise the role and impact of various natural and anthropic factors in the location and development of the main types of farmers, and their policy implications. 相似文献
9.
近年来,铁路短途城际客运得到了很大的发展,开行城际列车已成为铁路运输企业新的经济增长点。新财务清算政策实施后,开行城际列车的效益受到一定程度的影响,针对存在的问题,就如何提高其效益水平进行了讨论。提出了完善开行结构、增加营业收入、减少客运付费、降低成本支出等建议措施。 相似文献
10.
从建设项目对生态经济的影响,建设项目生态经济的评价以及自然资源价值对建设项目评价的影响,论证了建设项目与生态经济对立统一的关系,提出了建设项目环境保护的重要性,建设性的提出了如何进行建设项目中的生态经济效益分析和评价,具有一定的现实意义。 相似文献