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951.
区域分工对区域经济发展具有重要作用。山东地处我国东部沿海,是全国人口大省、经济大省,在全国经济发展格局中占有举足轻重的地位。根据区域分工理论,对山东省在全国和区域内部分工进行了分析,揭示了山东省在全国的区际地位以及所辖17个市之间的区域分工与合作格局,为山东省强化区域分工和联系,提高区域竞争力提供决策依据。 相似文献
952.
2006年12月、2007年1—4月对湛江市寸金公园的鸟类资源状况进行了初步的研究,共记录到鸟类16种,隶属4目10科。其中,雀形目鸟类最多,共7科11种,约占总数的69%;其次为佛法僧目1科2种,约占总数的12.5%;鸡形目和鹃形目各1科1种,约占总数的6.25%。其中有国家Ⅱ级保护鸟类1种,占总数的6.25%。此外,属国家林业局发布的"国家重点保护的有益、有经济价值或有科学研究价值的动物"的鸟类7种,占总数的43.75%;被纳入省级重点保护鸟类的有2种,占总数12.6%;被纳入中澳候鸟协定鸟类的有1种,占总数的6.25%。 相似文献
953.
954.
We demonstrate an approach for evaluating the level of protection attained using a variety of forms and levels of past, current,
and proposed Air Quality Standards (AQSs). The U.S. Clean Air Act requires the establishment of ambient air quality standards
to protect health and public welfare. However, determination of attainment of these standards is based on ambient pollutant
concentrations rather than prevention of adverse effects. To determine if a given AQS protected against adverse effects on
vegetation, hourly ozone concentrations were adjusted to create exposure levels that “just attain” a given standard. These
exposures were used in combination with a physiologically-based tree growth model to account for the interactions of climate
and ozone. In the evaluation, we used ozone concentrations from two 6-year time periods from the San Bernardino Mountains
in California. There were clear differences in the level of vegetation protection achieved with the various AQSs. Based on
modeled plant growth, the most effective standards were the California 8-hr average maximum of 70 ppb and a seasonal, cumulative,
concentration-weighted index (SUM06), which if attained, resulted in annual growth reductions of 1% or less. Least effective
was the 1-hr maximum of 120 ppb which resulted in a 7% annual reduction. We conclude that combining climate, exposure scenarios,
and a process-based plant growth simulator was a useful approach for evaluating effectiveness of current or proposed air quality
standards, or evaluating the form and/or level of a standard based on preventing adverse growth effects. 相似文献
955.
Because American national forests are managed for all citizens, it is important that researchers explore the differences and
similarities between citizens living both near and far from publicly managed land. We surveyed residents living at various
distances from nationally managed land to collect resident perceptions of different forest fire-management techniques, to
determine public preferences for these techniques, and to examine the motivations behind these preferences. Participants both
close to and far away from national forests tended to favor a multipronged approach to fire management by preferring the use
of a combination of two or more fire-management techniques. There were no significant differences by proximity in participants’
self-rated emotions, types of fire-management techniques preferred, or the reasons and rationales for their preferred fire-management
technique(s), indicating that the proximity variable may not be as significant as previously thought. 相似文献
956.
River damming provides a dominant human impact on river environments worldwide, and while local impacts of reservoir flooding
are immediate, subsequent ecological impacts downstream can be extensive. In this article, we assess seven research strategies
for analyzing the impacts of dams and river flow regulation on riparian ecosystems. These include spatial comparisons of (1)
upstream versus downstream reaches, (2) progressive downstream patterns, or (3) the dammed river versus an adjacent free-flowing
or differently regulated river(s). Temporal comparisons consider (4) pre- versus post-dam, or (5) sequential post-dam conditions.
However, spatial comparisons are complicated by the fact that dams are not randomly located, and temporal comparisons are
commonly limited by sparse historic information. As a result, comparative approaches are often correlative and vulnerable
to confounding factors. To complement these analyses, (6) flow or sediment modifications can be implemented to test causal
associations. Finally, (7) process-based modeling represents a predictive approach incorporating hydrogeomorphic processes
and their biological consequences. In a case study of Hells Canyon, the upstream versus downstream comparison is confounded
by a dramatic geomorphic transition. Comparison of the multiple reaches below the dams should be useful, and the comparison
of Snake River with the adjacent free-flowing Salmon River may provide the strongest spatial comparison. A pre- versus post-dam
comparison would provide the most direct study approach, but pre-dam information is limited to historic reports and archival
photographs. We conclude that multiple study approaches are essential to provide confident interpretations of ecological impacts
downstream from dams, and propose a comprehensive study for Hells Canyon that integrates multiple research strategies. 相似文献
957.
介绍了环境监测信息网络的组成、作用于流通范围,提出了环境监测信息的构架、环境数据库的设计原则、环境监测应用软件的开发思路,以及环境监测信息网络的管理与维护措施。 相似文献
958.
本文简要介绍了环境监测技术规范中所规定的数值修约规则及相关规范要求的主要内容,并给出了相应的Excel修约公式和修约函数,可方便地用于对环境监测工作中实验测定和计算得出的各种数值进行修约。修约公式是一个利用Excel工作表函数构造的满足数值修约基本规则的工作表计算公式,在给定修约位数的前提下,可直接在工作表单元格中使用修约公式对数值进行修约,对于简单应用,具有方便、快捷、直观的特点。修约函数是一个利用Excel VBA编制的自定义函数,共有四个参数,其调用方法同工作表函数,具有针对性强、灵活、便捷的特点,可根据环境监测技术规范的特定要求,实现自动按有效位数或小数位数进行数值修约,并按相应的格式输出数据。 相似文献
959.
河北省钢铁工业主要大气污染物减排潜力分析 总被引:1,自引:0,他引:1
通过对河北省钢铁工业存在问题的分析,得出我省钢铁行业主要大气污染物为二氧化硫和粉尘.结合我省钢铁企业的实际情况,从工程技术、政策管理等方面提出相应治理措施,并对"十一五"期间我省钢铁行业二氧化硫和粉尘减排效益进行预测.预测结果显示:采用所建议的减排措施后,我省钢铁工业二氧化硫减排量对全省"十一五"减排计划的贡献率为81.4%;粉尘可减排60%. 相似文献
960.