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991.
Variations in the parameters of the life cycle in freshwater prawns of the genus MacrobrachiumBate and some populations of the species Macrobrachium nipponense(De Haan) were analyzed comparatively. Using factor analysis, these parameters were systematized and expressed through two factors. The first factor is related to the parameters of larval development and the dimensions of an egg, and the second, to the length of adults and their fecundity. The greatest differences in the values of intrageneric and intraspecific variation of parameters are noted for the dimensions of larval stages. It is assumed that the formation of a species proceeds primarily through the appearance of adaptations at larval stages. 相似文献
992.
本文结合儋州市第二期农业综合开发的实践,客观地总结了该市所取得的成绩,较详细地剖析了成功的原因,并提出了综合开发儋州市农业的建议. 相似文献
993.
Impacts after four years of experimental trampling on alpine/sub-alpine environments in western Tasmania 总被引:2,自引:0,他引:2
Experimental trials were undertaken over four years to assess the impact of recreational trampling in undisturbed alpine and sub-alpine vegetation communities in the Western Arthur Range, western Tasmania. Data on 'pad' formation due to human trampling were collected using vegetation cover assessments, biomass estimates and detailed cross-sectional surface profiles. In sub-alpine buttongrass and alpine herbfield, prolonged and sustained damage may occur after 100 passes by walkers. The environmental threshold of the flat alpine herbfield site was breached after 200 passes. Plant morphology was one determinant of resistance and resilience, with upright woody shrubs and tall tussock graminoids most vulnerable to sustained trampling damage. Cushions are susceptible to trampling impacts at 500 passes. Loss of vegetation cover peaks 6-12 months after trampling. Our results show that pads formed with as few as 30-100 passes per annum and tracks form at between 100 and 500 passes per annum. Two years after the cessation of trampling, there is some small recovery in vegetation cover after 30 and 100 passes per annum applied for three years, but no evidence of recovery at the 500 pass treatments. The low trampling threshold and slow recovery rates in western Tasmania suggest that concentrating walkers on a minimal number of sites may be the best management option for these untracked alpine and sub-alpine environments. 相似文献
994.
Carlos Wing-Hung Lo 《Environmental management》1995,19(3):331-344
Within the context of political democratization, this article explores environmental protection in Hong Kong since the government
lauched a ten-year program to “save the environment” in 1989. Examining environmental management by law from a social-choice
perspective, it argues that the government has yet to reach an integrative policy orocess. Hence the preconditions for an
integrative set of environmental legislation are absent. Institutionally, without a comprehensive green policy, the current
arrangements lack a vision as an integrative force to promote effective coordination among various sectoral environmental
coordination among various sectoral environmental programs. The dominant approach of policy and law enforcement through consultation
has rendered impossible strict enforcement of environmental rules and regulations as local economic growth enjoys a priority
over environmental protection. At a time of environmental awakening, the people of Hong Kong are not yet prepared awakening,
the people of Hong Kong are not yet prepared to participate in environmental management in a strict legal manner. The overall
observation is that Hong Kong has yet to see more mature political, legal, administrative, and social conditions for managing
its environment within a legal framework. 相似文献
995.
996.
997.
Both the Aalborg Commitments and the guidance on integrated urban environmental management and sustainable urban transport
plans proposed by the EU Thematic Strategy on the Urban Environment foresee a baseline review as the first step in developing
integrated urban management plans and systems. A baseline review of urban sustainability undertaken in Riga reveals significant
discrepencies between the sustainability criteria of the Aalborg Commitments and the: responsibilities and competencies of
the municipal government and administration as defined by statutes; policy goals and measures defined in municipal planning
documents; policy goals and measures defined in the Riga Development Plan. To better orient the mandate of the municipality
towards sustainable development, municipal statutes should be supplemented to more fully reflect the issues defined by the
Aalborg Commitments and should include sustainability as a goal. In order to strengthen the implementation of sustainable
development specific policy goals, measures and targets should be formulated for all the Aalborg Commitments issues when revising
existing municipal planning documents or developing a municipal sustainable development management plan. An analysis of the
European Common Indicators and the State of the Environment in Riga 2001 indicators indicates that they can only partially
fulfill a monitoring function for the implementation of the Aalborg Commitments. This highlights a need to better coordinate
sustainable development initiatives at the European level. The methodology used for the baseline review in Riga is useful
for assessing the status of urban sustainability when preparing integrated urban management plans or systems, but requires
testing elsewhere.
Readers should send their comments on this paper to BhaskarNath@aol.com within 3 months of publication of this issue. 相似文献
998.
我国经济飞快的发展速度,不但丰富了人们的生活内容、方便了人们的生活,而且还在人们生活中产生了一些负面影响,大气污染问题已经引起了国家政府以及我国民众的一致关注,国家还为此制定并颁布了相关的整顿治理措施,在大气环境治理方面,大气监测是重要手段,本文对大气环境监测全过程质量控制问题展开分析研究。 相似文献
999.
为了实现治霾目标,国家大力推广可再生能源应用,《关于促进地热能开发利用的指导意见》(国能新能[2013]48号),明确提出将积极推广浅层地温能,扩大其在城镇建筑用能中的比例。我国浅层地温能产业发展面临一系列障碍,为了克服市场调节失灵问题,借助事物发展动力原则,结合全寿命周期理论,依托层次分析法,推导能源发展的核心影响因素,据此提出了浅层地温能产业规模化发展的关键路径,构建了浅层地温能开发利用的长效管理体系。 相似文献
1000.