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In studies conducted from 1982 to 1983, productivity (14C uptake) of a coral reef algal-turf assemblage was unaffected by oxygen concentration but decreased when pH rose, probably in response to declining CO2 and HCO
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supplies. Release of prefixed 14C was substantially lower in the light than in the dark and was unaffected by oxygen concentration. Release of organic prefixed 14C was greater in the light than in darkness. Total CO2 compensation-points were low, showing no consistent response to oxygen or the photorespiratory inhibitor alpha-hydroxy-2-pyridine-methanesulfonic acid (HPMS). Oxygen has little if any influence upon turf productivity, which was high in comparison to other benthic algae. Decreases in net carbon-fixation rates of this turf more likely result from decreased photosynthesis than increased photorespiration, which is either not significant in turf metabolism under natural conditions or is compensated by efficient refixation of respired carbon.This paper describes research by J. M. Hackney in partial fulfillment of the requirements for the Ph.D. degree at Georgetown University 相似文献
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This article presents a review of the current municipal solid waste (MSW) and domestic waste generation and recovery situation
in Hong Kong and identifies the factors affecting the waste generation rates. The results show that before 1997, MSW and domestic
waste generation rates were driven by population growth and growth in the gross domestic product, with the latter having the
larger effect. But recent waste generation data show poor correlation between waste generation rates and economic and population
figures due to the increase in recycling efforts in the community. The results are also reported of a small-scale survey to
explore the public attitude to waste recovery. The results show that most domestic householders have developed habits to carry
out separation of waste at source for recycling, but the amount of recyclables recovered was low. 相似文献
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The effects of chronic copper exposure on growth and physiological responses of the green mussel Perna viridis were investigated by exposing the mussels to 50 μg l−1 Cu for 3 mo at 17 and 25 °C. These temperatures represent, respectively, the winter and summer seawater temperatures in Hong
Kong. Differences in the level of response between mussels exposed for 3 mo to 50 μg Cu l−1 generally increased with duration of exposure. The tissue concentration of copper had increased by 280 and 450% after 3 mo
exposure at 17 and 25 °C, and growth performances were reduced, with the 25 °C sets suffering from larger negative impact
of copper in most responses. The inhibitory effects of copper on production of the various body components generally followed
the order linear shell growth (greatest) > tissue production > byssus production > shell production. There were also decreases
in the condition index (43 and 35% reductions at 17 and 25 °C), clearance rates (10.3 and 18.5%), faeces production (11 and
16.3%), assimilation efficiency (6.8 and 9.2%) and oxygen consumption rate (12.8 and 24.8%). In contrast, the organic content
of the faeces (9.2 and 13.2% increases at 17 and 25 °C) and rate of ammonia excretion (21 and 28.6%), increased upon chronic
copper exposure. Many of the responses (e.g. changes in tissue copper content, body dry wt, shell organic content, clearance
rate and oxygen consumption rate) exhibited fluctuating levels of impact during prolonged copper exposure, while others (e.g.
faecal production rate, assimilation efficiency, tissue organic content) demonstrated steady decreasing trends with increasing
exposure time.
Received: 17 September 1999 相似文献
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Sze‐Sze Wong 《组织行为杂志》2008,29(5):591-614
Drawing from the structural perspective of social capital theory, this research investigates how internal and external advice network structures influence knowledge overlap and variety and, how these knowledge dimensions in turn influence group effectiveness. Findings from two studies on knowledge‐intensive groups indicate that different advice network structures are associated with knowledge overlap and knowledge variety, and only knowledge variety was significantly associated with group effectiveness. In addition, despite implicit understanding that advice networks aid performance through enhancing knowledge outcomes, only knowledge variety was found to mediate the relationship between external network and group effectiveness. Implications for theory and practice are discussed. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献