城市协调发展理论与对策的探讨

本文对城市科技、经济、社会、环境协调发展结构、功能、机理、机制及对策进行了探讨.     

基于SPSS的苏北地区可持续发展能力空间分异研究

以区域可持续发展能力建设为切入点,结合苏北地区的实际,建立适合该地区的可持续发展能力评价指标体系,然后运用SPSS软件的因子分析和聚类分析的方法,对苏北地区可持续发展能力进行综合评价。结果表明,区内各县市可持续发展能力差异较大,但其空间分异呈现出某些特征:经济可持续发展能力呈现由地区东南部向中间递减的“一”字型空间格局;资源环境可持续发展能力呈现由地区中部分别向东、向西递减的“凸”字型空间格局;社会可持续发展能力呈“M”字型空间格局;综合可持续发展能力呈“H”字型空间格局;以中心城市为核心,可持续发展能力向周边呈辐射状递减趋势。根据这些空间分异特征,提出了一些促进苏北地区可持续发展能力建设的建议。     

鱼类耳石元素指纹研究进展

耳石是沉积在真骨鱼类内耳中的一种矿物结构,其主要成分是碳酸盐.在鱼类的生活过程中,水环境中的化学元素经过代谢稳定地沉积在耳石上,由于生活水域化学环境的差异,鱼类耳石的元素组成或含量存在一定的差异,而使耳石上的元素指纹成为一种天然标志,记录了鱼类所经历的生态环境及其变化.耳石元素指纹研究主要包括同位素成分分析、锶钙比率研究(Sr/Ca)以及一些痕量元素分析等,这些可以用于鱼类种群识别、生活史研究、生活环境重建,以及高龄鱼的年龄鉴定,在鱼类生态学和渔业资源学研究中具有广泛的应用前景.参57     

Diet quality affects an attractive white plumage pattern in dark-eyed juncos (Junco hyemalis)

Sexually selected traits that act as signals of quality often display some degree of condition dependence. In birds, condition dependence of ornamental plumage is often mediated by production costs related to acquisition or allocation of dietary resources. White plumage ornaments, however, have often been assumed to be inexpensive because their production requires neither pigment nor specialized feather structure. In male dark-eyed juncos (Junco hyemalis), the size of a white patch on the tail contributes to attractiveness and mating success. Using captive males, we examined the effects of diet quality on the size and brightness of the tail-white patch. After removing four tail feathers to induce replacement, we maintained subjects on a subsistence (low-protein) or enriched (high-protein) diet while induced feathers grew. Birds that received an enriched diet grew their feathers more quickly and grew larger, brighter white patches. Feather growth rate was positively correlated with the increase in the size of the tail-white patch, a relationship that was stronger in the subsistence diet group. However, within diet treatments, faster-grown feathers were slightly duller. Taken together, these results suggest that variation in diet quality may lead to condition-dependent expression of tail white and that condition dependence may be stronger in more stressful environments. We suggest a mechanism by which increased feather growth rate may lead to an increase in the size of the tail-white patch and discuss potential trade-offs between signal size and brightness.     

Female guppies shorten brood retention in response to predator cues

Predation risk influences the duration of offspring development in many species where embryos develop from externally shed eggs. Surprisingly, such predator-mediated effects on offspring development have rarely been explored in live-bearers. In this paper, we use the guppy (Poecilia reticulata), a live-bearing freshwater fish, to test whether the duration of brood retention (the time from mating to parturition) is influenced by experimental changes in the perceived level of predation. Because the swimming performance of female guppies is impaired during late pregnancy, we predicted that females would withhold broods for shorter periods when they are exposed to cues that signal a heightened risk of predation on adults rather than on juveniles. We therefore simulated increased risk of predation on adults by using a combination of pike-shaped models (resembling natural predators that prey on adult guppies) and ‘alarm substances’ derived from the skin extracts of adult conspecific females. Our results revealed that, under simulated predation risk, female guppies produced broods significantly more quickly than their counterparts assigned to a control group where predator cues were absent. A subsequent evaluation of offspring swimming performance revealed a significant positive association between neonate swimming speeds and the duration of brood retention, suggesting that by accelerating parturition, females may produce offspring with impaired locomotor skills. These findings, in conjunction with similar results from other live-bearing species, suggest that the conditions experienced by gestating females can generate significant variation in the timing of offspring development with potentially important implications for offspring fitness.     

南岳衡山旅游业持续发展初探

通过分析南岳衡山旅游业发展的历史背景、现状、旅游优势、存在的问题,着重探讨南岳衡山旅游业持续发展及其对策.     

生态供应链与生态型设计

生态供应链是可持续发展思想在运作管理领域的具体应用。生态型设计兼顾了经济效益和生态效益，是生态供应链的核心内容。生态型设计的实质是通过整体优化和局部优化来降低各节点企业的环境影响，借助于生态型设计可以把传统供应链代表的单程经济转化成生态供应链代表的循环经济。生态型设计由生态供应链的整体设计和组成元素的设计两部分组成，具体内容包括产品设计、原材料采购、产品生产、产品营销、产品回收和反向物流。     

大连市环保产业发展趋势分析

介绍了大连市近年来环保产业的发展状况,分析了大连市环保产业市场的特点。对未来15年的发展趋势作了预测,指出了今后面临的挑战和机遇。     

积极发展绿色食品

叙述了绿色食品的概念、特点、标准，并对我国绿色食品的发展历程、发展现状和发展前景进行了分析。