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841.
根据2003年-2006年浙江、武汉两地火灾事件发生情况,应用变异系数、法诺因子、阿伦因子的统计分析方法,对城市火灾事件的时间标度行为进行了分析。结果显示,城市火灾序列具有一定的时间丛集性特征,且在达到一定的时间尺度后呈现出较为明显的分形特征,该分形自相似性特征具有普适性和稳定性。同时发现,一定时间尺度范围内城市火灾时间序列的分形特征与时间窗口的取值无关。 相似文献
842.
By expanding Frankel and Rose's (2009) theoretical model to consider the interaction of commodity prices with both money liquidity and expectation formation, this paper empirically studies the long-run relationship and short-term dynamics between aluminum prices and money liquidity via Vector autoregressive (VAR) and Impulse Response Function methodologies. Our results show that: (1) a cointegration relationship between money liquidity and Chinese aluminum prices exists, and monetary liquidity positively significantly influences the price over long periods; (2) a structural change has been found during the 2008 Financial Crisis and the change of Chinese monetary policies; and (3) the negative impact of production capacity mechanism on aluminum prices coexists with the positive impact of financial asset returns mechanism, to allow for varied market expectations on aluminum prices within and outside China. 相似文献
843.
Rebecca Adler Miserendino Bridget A. Bergquist Sara E. Adler Jean Remy Davée Guimarães Peter S.J. Lees Wilmer Niquen P. Colon Velasquez-López Marcello M. Veiga 《Resources Policy》2013
Portovelo-Zaruma, Ecuador is an artisanal and small-scale gold mining (ASGM) region with approximately 6000 gold miners working with mercury and cyanide. Although artisanal gold mining (AGM) has taken place in Portovelo-Zaruma for centuries, highly mechanized small-scale gold mining (SGM) processing plants capable of increased throughput began being built in the 1990s. While there are benefits associated with ASGM, there are also negative impacts experienced by the miners and the surrounding communities. To take advantage of ASGM as a poverty-alleviating mechanism while reducing unwanted externalities, the cumulative impacts must be understood. Numerous challenges to measuring, monitoring, and addressing ASGM impacts result from the complexity of the impacts themselves, the nature of the gold mining as an informal industry, and the shortfalls in the current regulatory framework. These are discussed in the context of ongoing, unresolved issues including efforts to address trans-boundary water pollution, management of mining waste, and conflicts regarding priorities, ambiguities, and enforcement of existing regulations and policies. Internationally, interventions to address both AGM and SGM impacts have typically focused almost exclusively on technological changes through the elimination of mercury use. Our analysis suggests that to better address ASGM and their cumulative impacts in Ecuador, it will be beneficial to revisit the legal definitions of AGM and SGM. Additionally, promotion of information-based strategies including educational outreach programs and cross-scale and cross-level mitigation methods may also be beneficial. The success of these strategies to reduce ASGM-related cumulative impacts will depend on sufficient funding and the commitment of stakeholders. 相似文献
844.
Martin J. Steinbauer Fredrik Östrand Tom E. Bellas Anna Nilson Fredrik Andersson Erik Hedenström Michael J. Lacey P. Florian Schiestl 《Chemoecology》2004,14(3-4):217-223
Summary. The autumn gum moth, Mnesampela privata
(Guenée) (Lepidoptera: Geometridae), is native to Australia
and can be a pest of plantation eucalypts. Field-collected
and laboratory-reared female autumn gum moths were
dissected to remove glands likely to contain components of
the sex pheromone. Using gas chromatography (GC) and
combined gas chromatography–mass spectrometry (GC-MS),
three compounds were identified from female extracts,
namely (3Z,6
Z,9
Z)-3,6,9-nonadecatriene, 1-hexadecanol
and 1-octadecanol (confirmed by comparison with synthetic
samples). Nonadecatriene elicited an antennal response in
male autumn gum moth during gas chromatographic
analyses combined with electroantennographic detection
(GC-EAD). In electroantennogram (EAG) recording male
M. privata antennae responded to the nonadecatriene. Nonadecatriene was synthesised via Kolbe electrolysis,
starting with (9Z,12Z,15Z)-octadeca-9,12,15-trienoic acid
(linolenic acid) and propanoic acid or via an alternative
four-step method also starting from linolenic acid. In field
trials (3Z,6Z,9Z)-3,6,9-nonadecatriene proved attractive
to male moths. Thus, we conclude that (3Z,6Z,9Z)-3,6,9-
nonadecatriene is a sex pheromone component of autumn
gum moth. This component has been identified in extracts
from other geometrids in the same subfamily, Ennominae.
However, to our knowledge this is the first example where
(3Z,6Z,9Z)-3,6,9-nonadecatriene has been found in females
and also proved attractive to male moths when presented on its
own. Our results are discussed in relation to other geometrid
pheromones. 相似文献
845.
846.
Based on the results of long-term field studies (1980–1997) and published data on the ecology of the northern mole vole (Ellobius talpinusPall.), it is assumed that these animals living in the Southern Urals and the Transural region do hibernate. The factors that cause their hibernation (freezing of the ground, the resultant unavailability of food, and hypoxia), some indirect evidence for hibernation (the cessation of tooth root growth from autumn to spring and a long life span), and characteristic signs of the preparation for hibernation (a decrease in body weight and an increase in liver weight) are considered. A hypothetical scheme of the active and dormant periods is proposed. 相似文献
847.
848.
849.
Exposure to environmental contaminants has been shown to alter normal thyroid function in various wildlife species, including the American alligator (Alligator mississippiensis). Abnormalities in circulating levels of the thyroid hormone thyroxine (T4) have been reported in juvenile alligators from several contaminated lakes in Florida. To further elucidate these functional thyroid abnormalities, this study examines the structure of thyroids and circulating T4 concentrations from juvenile alligators collected from three sites of varying contamination on Lake Okeechobee, Florida. The following variables were used to characterize thyroid morphology: epithelial cell height, width and area, percent colloid, and follicle area. These variables were compared among study sites and between genders. No difference was detected in epithelial cell height, epithelial cell area, or follicle area among the sites, whereas significant differences in epithelial cell width (p=0.02) and percent colloid (p=0.008) were found. Animals from the most contaminated site (Belle Glade) had significantly greater epithelial cell widths and significantly less colloid present in their follicles compared to animals from the reference site (West). Gender did not have a significant interaction with site for any variable measured. Thyroxine (T4) concentrations were elevated in the intermediately contaminated site (Conservation Area 3A) compared to the other sites (p<0.0001). It is proposed that the disruptions seen in Lake Okeechobee alligators are due to disruptions at both the thyroid and extra-thyroidal tissues. 相似文献
850.
长江三角洲是我国沿海规模最大的经济区 ,上海市、江苏沿江的南京、镇江、扬州、泰州、苏州、无锡、常州、南通等八市、浙江省的嘉兴、湖州、杭州、宁波、绍兴、舟山等六市都属于长江三角洲经济区的范围 ,土地总面积 996 87.5km2 ,占全国土地总面积的 1%。 1998年全区人口 74 4 5 .6 9万人 ,GDP总量 12 70 1.39亿元。长江三角洲是我国经济最发达 ,人口分布最密集 ,城市化水平最高的地区之一。阐明了长江三角洲开发区建设和发展的基本特征。指出 ,长江三角洲是我国对外开放最早 ,开发区建设数量最多 ,类型最齐全的地区 ,它拥有经济技术开发区、高新技术开发区、农业现代化园区、旅游度假区和保税区等多种类型。经过多年来的开发建设 ,长江三角洲开发区投资的基础设施环境和社会软环境都很好 ,在招商引资方面取得了巨大成就。这些开发区已经成为了其地方经济新的增长点 ,新的制造业基地 ,高科技发展基地 ,外商投资和跨国公司的集聚地。通过对上海、江苏、浙江各种类型开发区的外商投资规模、产业经济结构、城市建设功能和外向型经济格局的比较 ,揭示了长江三角洲开发区建设和发展的区域差异。明确了上海开发区建设在长江三角洲的龙头地位 ,分析了浙江省开发区建设落后于江苏省的主要原因 ,总结出了愈靠近 相似文献