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1.
鸭绿江下游及河口附近水质现状评价及变化趋势 总被引:1,自引:0,他引:1
作者根据1991 ̄1995年鸭绿江下游及河口附近水质监测结果,对该区域水体的污染作出分析和评价,提出鸭绿江下游水质逐年好转,河口附近水质逐年变坏的观点,并利用灰色理论对1996 ̄2000年期间水体中的主要污染物--石油类的变化趋势作出预测。 相似文献
2.
在盒形件拉伸成形过程中,毛料展开是冲压工作的重要课题。此文根据数学理论,用亚椭圆方法建立数学模型来摸拟盒形件毛料尺寸展开外形,是提高一次成形、减少压延次数的有效方法。 相似文献
3.
Jari Syväranta Julien Cucherousset Dorothée Kopp Aurélia Martino Régis Céréghino Frédéric Santoul 《Die Naturwissenschaften》2009,96(5):631-635
Many anadromous fish species, when migrating from the sea to spawn in fresh waters, can potentially be a valuable prey for
larger predatory fish, thereby efficiently linking these two ecosystems. Here, we assess the contribution of anadromous fish
to the diet of European catfish (Silurus glanis) in a large river system (Garonne, southwestern France) using stable isotope analysis and allis shad (Alosa alosa) as an example of anadromous fish. Allis shad caught in the Garonne had a very distinct marine δ13C value, over 8‰ higher after lipid extraction compared to the mean δ13C value of all other potential freshwater prey fish. The δ13C values of European catfish varied considerably between these two extremes and some individuals were clearly specializing
on freshwater prey, whereas others specialized on anadromous fish. The mean contribution of anadromous fish to the entire
European catfish population was estimated to be between 53% and 65%, depending on the fractionation factor used for δ13C. 相似文献
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5.
Water management in Uzbekistan (Central Asia) is facing tremendous challenges. They are rooted in past and present environmental degradation, the socio-economic transition after the breakup of the Soviet Union, and the impacts of climate change. The Uzbek government has initiated reforms in the agricultural and water sectors to steer the socio-economic transition and address the threats of increasing water scarcity and decreasing agricultural productivity. However, despite the urgency of the problems and massive international assistance changes to the water management regime have only been minimal so far. In this paper we identify major structural barriers for adaptation of the water management regime through an analysis of two recent policy processes. Both processes address pressing water management issues such as “coping with extreme events” and “providing water for ecosystems”. They were analyzed using the Management and Transition Framework as well as a group model building exercises with stakeholders on the national, regional and local levels. The analyses reveal a lack of vertical integration across administrative levels of the formal system and a still prevailing strong centralization of water management. Moreover the water management regime is strongly influenced by informal institutions that shape the outcomes of policy processes. The interactions guided by informal institutions provide an informal link between different administrative levels of the regime. However, those informal networks and the social capital embedded in them rather prevent needed changes. The resulting combination of top down institutional change initiated by socio-economic transition and bottom-up consolidation of the existing status quo via informal processes and networks prevents social learning. It also slows down an adaptation process that potentially could lead to a transition towards a more adaptive regime. 相似文献
6.
A rare chromosomal aberration consisting of a chromosomal shift was found in a woman who had prenatal diagnosis because she had previously had a malformed girl with phenotypic features compatible with the diagnosis of Patau syndrome. Chromosome analysis using G, C, and NOR banding showed a direct intrachromosomal insertion of bands 13q12 to 13q14 onto the short arm of chromosome 13 at band 13p13. We discuss this observation and compare it with other published reports of chromosomal shifts. 相似文献
7.
Klaus Eisenack Rebecca Stecker Diana Reckien Esther Hoffmann 《Mitigation and Adaptation Strategies for Global Change》2012,17(5):451-469
This paper identifies the literature that deals with adaptation to climate change in the transport sector. It presents a systematic
review of the adaptations suggested in the literature. Although it is frequently claimed that this socially and economically
important sector is particularly vulnerable to climate change, there is comparatively little research into its adaptation.
The 63 sources we found are analysed following an action framework of adaptation. This distinguishes different adaptational
functions and means of adaptation. By an open coding procedure, a total of 245 adaptations are found and classified. The paper
shows a broad diversity of interdependent actors to be relevant—ranging from transportation providers to public and private
actors and households. Crucial actors are hybrid in terms of being public or private. A substantial share of the identified
adaptations follows a top-down adaptation policy pattern where a public or hybrid operator initiates action that affects private
actors. Most of the exceptions from this pattern are technical or engineering measures. Identified adaptations mostly require
institutional means, followed by technical means, and knowledge. Generally, knowledge on adapting transport to climate change
is still in a stage of infancy. The existing literature either focuses on overly general adaptations, or on detailed technical
measures. Further research is needed on the actual implementation of adaptation, and on more precise institutional instruments
that fill the gap between too vague and too site-specific adaptations. 相似文献
8.
Bruce L. Umminger 《Die Naturwissenschaften》1978,65(3):144-150
The known cases elucidating the role of hormones in the regulation of physiological and biochemical changes which occur when fish are acclimated to low temperatures are sparse, but evidence is accumulating to implicate prolactin, glucagon, insulin and perhaps thyroxine and cortisol in at least some of the physiological adjustments observed in some species. The need for further research on hormonal control mechanisms at work during low-temperature acclimation is discussed, with special emphasis placed on neuroendocrine relationships. 相似文献
9.
As climate change adaptation is increasingly discussed and becoming a mainstream concept, different types of users are asking themselves if and when they should develop an adaptation strategy, often not knowing where to begin. Climate experts, on the other hand, have access to an enormous amount of data that could be useful to users but often do not know how to translate it into something practical. Both users and experts can be linked through two timescales, the system lifespan and climate vulnerability. While the system lifespan relies on the user’s estimation of his planning timeframe, the climate vulnerability is estimated from climate model projections and observations. We propose a simple tool to relate user and climate expert knowledge by combining the two timescales. To be reliable, the interconnection implies a dialogue to first identify what sensitive climate variable will impact the system and subsequently the extent of the impact. Climate data can then be used to identify, with the use of a simple graph, how sensitive a system is likely to be and help users position themselves about the urgency of adaptation. The concept has been successfully presented and applied to the tourism industry, notably the ski industry, which is showcased in this paper. 相似文献
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<正>应对气候变化,需要整合和应用多学科研究成果以最大程度地使区域和全球获益。今天,对气候变化的研究已经超越了自然科学的范畴,社会科学的视角被引入并发挥着越来越重要的作用。其中,气候传播的关注重点是如何使气候变化的科学信息更准确、高效地传播到目标受众,从而调动更多利益相关方一起参与到应对气候变化的实际行动中。考虑到占人口绝大多数的社会公众对应对气候变化成效发 相似文献
12.
It is now widely accepted that climate change is happening and that future changes will impact on many aspects of society,
including agriculture. To maintain food supplies, the agricultural industry must address climate change adaptation. Key to
this is the attitudes of those within the industry likely to have responsibility for adapting. This study investigated stakeholder
attitudes towards adaptation to climate change in the livestock industry. Findings reveal four attitudinal groups. First,
there is a ‘farmer-focused group’ that has a positive attitude about the ability of livestock farmers to adapt to climate
change, but that also has the opinion that they will need additional support to adapt. Second, there is an ‘incentive for
enterprise, anti-GM (genetic modification) group’ with an attitudinal position stressing that the government should have a
role in implementing regulations and providing finance. This group has a negative attitude towards GM technology and does
not think it will be the answer to climate change. Third, there is an ‘information and education group’ whose attitude is
that the provision of information is crucial for ensuring that the livestock industry adapts. Fourth, there is a ‘pro-technology
group’ who have a positive attitude towards GM technology and who are therefore willing to embrace it as the route to adaptation.
Three of these four groups favour soft adaptations that maintain flexibility within the system, and only the fourth is of
the opinion that adaptive capacity is not an issue and that the industry is ready to implement hard adaptations. 相似文献
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14.
A strategy to deal with water crisis under climate change for mainstream in the middle reaches of Yellow River 总被引:1,自引:2,他引:1
Xiao-jun Wang Jian-yun Zhang Rui-min He ElMahdi Amgad ElSawah Sondoss Man-ting Shang 《Mitigation and Adaptation Strategies for Global Change》2011,16(5):555-566
Our planet is increasingly threatened by degradation in water quantity and quality due to climate change, population growth
and development pressures. Water shortage is one of the most challenging environmental problems to humankind in the 21st century
under the changing climate. Water shortages and scarcity escalate risks to food security and economic viability. For decades,
water management has been dominated by supply oriented paradigm of expanding the capacity of accessible water (e.g. building
dams). While large scale infrastructure projects provided effective solutions for chronic water crises in the past, they have
come at expensive, irreversible and delayed ecological, economic and social costs. As more questions are raised concerning
over reliance on infrastructure solutions, discussions about a sustainable future suggest a greater focus on the demand side
of the equation is needed. In this paper, we use multi-recursive and runoff coefficient analysis methods to analyze the annual
runoff of the mainstreams (Kuye River, Tuwei River, Wuding River and Jialu River) in the middle reaches of Yellow River. The
main objective is to estimate the impacts of climate change and human activity on water resources in the study area and test
the potential of water demand management to lessen the gap between supply and demand. Results show remarkable drop in the
average annual runoff as a combined effect of climate change and human activity. Moreover, results show that human activities
are the direct reason for the changes of river runoff, and the proportion of human activities account the biggest is Wuding
river, next is Kuye river, Jialu river is smallest, these changes lead to the decrease of river runoff, and even drying up
in recent years. This result highlights the importance of using WDM to diminish the increasing gap between demand and supply.
Motivated by this, the paper presents a comprehensive framework for implementation WDM in the middle reaches of Yellow River.
The framework includes a wide range of instruments: legislative, economic, technological and educational. The core step of
the framework, collaboration among water planners, water service providers and end-users lies as an essential mechanism for
achieving long term trade-offs between ecological and socio-economic water needs. 相似文献
15.
K. E. Kunkel H.-C. Huang X.-Z. Liang J.-T. Lin D. Wuebbles Z. Tao A. Williams M. Caughey J. Zhu K. Hayhoe 《Mitigation and Adaptation Strategies for Global Change》2008,13(5-6):597-606
An air quality modeling system was used to simulate the effects on ozone concentration in the northeast USA from climate changes projected through the end of the twenty-first century by the National Center for Atmospheric Research’s (NCAR’s) parallel climate model, a fully coupled general circulation model, under a higher and a lower scenario of future global changes in concentrations of radiatively active constituents. The air quality calculations were done with both a global chemistry-transport model and a regional air quality model focused on the northeast USA. The air quality simulations assumed no changes in regional anthropogenic emissions of the chemical species primarily involved in the chemical reactions of ozone creation and destruction, but only accounted for changes in the climate. Together, these idealized global and regional model simulations provide insights into the contribution of possible future climate changes on ozone. Over the coming century, summer climate is projected to be warmer and less cloudy for the northeast USA. These changes are considerably larger under the higher scenario as compared with the lower. Higher temperatures also increase biogenic emissions. Both mean daily and 8-h maximum ozone increase from the combination of three factors that tend to favor higher concentrations: (1) higher temperatures change the rates of reactions and photolysis rates important to the ozone chemistry; (2) lower cloudiness (higher solar radiation) increases the photolysis reaction rates; and (3) higher biogenic emissions increase the concentration of reactive species. Regional model simulations with two cumulus parameterizations produce ozone concentration changes that differ by approximately 10%, indicating that there is considerable uncertainty in the magnitude of changes due to uncertainties in how physical processes should be parameterized in the models. However, the overall effect of the climate changes simulated by these models – in the absence of reductions in regional anthropogenic emissions – would be to increase ozone concentrations. 相似文献
16.
The Science of Nature - 相似文献
17.
Micrographs of retinas from the deep-sea fish Cataetyx laticeps revealed visual cells containing membranous whorls in the ellipsoids of the inner segments resulting from stretching and
modifications of the mitochondria membranes and their cristae. These pathological structures seem to be homologous to the
whorls observed in retinas of human carriers of Tay-Sachs disease. This disease, a genetic disorder, is found in humans and
some mammals. Our findings in fish suggest that the gene responsible can be found throughout the vertebrate evolutionary tree,
possibly dormant in most taxa.
Received: 20 April 2000 / Accepted in revised form: 16 June 2000 相似文献
18.
In insect societies, the presence and condition of egg-layers can be assessed with pheromones. Exocrine secretions are expected to vary in time in order to give up-to-date information on an individuals reproductive physiology. In the queenless monogynous ant Streblognathus peetersi, we allowed a previously infertile high-ranking worker to accede to the alpha rank, thus triggering the onset of her oogenesis (15 replicates). We then studied her interactions with an established egg-layer from the same colony after different durations, ranging from 20 h to several days. Even though her eggs are only ready to be laid after 30 days, the new alpha was recognised within 1–2 days. Detection occurred at a distance of a few millimetres, suggesting the involvement of a pheromone with low volatility, such as cuticular hydrocarbons. When the new alpha had differentiated for >48 h, she was attacked by the established egg-layer. In all cases, low-ranking workers eventually immobilised one of the two alphas: the new alpha was the target if she had differentiated only recently, suggesting that police workers select the dominant worker with the less fertile odour. Using the behaviour of ants as our measure, we demonstrate that a dominants olfactory signal changes rapidly with a modification in her social status, and it occurs well before the onset of egg-laying. 相似文献
19.
The invertebrate neuromodulator octopamine is known to be involved in bees' associative learning, enhancing the responsiveness of a bee to a conditioned stimulus. In this study, we tested the effect of octopamine on the choice behavior of free-flying bumblebees using a two-phase experiment in an array of artificial flowers. During the first phase of the experiment, the bee was allowed to collect octopamine-laden sugar water from two types of equally rewarding flowers (yellow versus blue). In the second phase, one type of flower was set to be unrewarding. The behavior of the bee (proportion of visits to the unrewarding flowers) over the two phases was fitted to a sigmoid regression model. Our results show that octopamine had no significant effect on the bees' equilibrium choice or on the overall rate of the behavioral change in response to the change in reward. Rather, octopamine significantly affected the time interval between the change in reward status and the initiation of behavioral change in the bee. 相似文献
20.
Slobodan Djordjevi? David Butler Philippe Gourbesville Ole Mark Erik PascheAuthor vitae 《Environmental Science & Policy》2011,14(7):864-873
In the context of urban flood management, resilience is equal to resisting, recovering, reflecting and responding. The variety of causes of flooding and their consequences underpin the need for increased and internationally coordinated efforts to enhance technologies and policies for dealing with floods. This paper addresses this issue and presents some novel research ideas related to resilience to flooding in urban areas, which are under development within the EU FP7 project ‘Collaborative research on flood resilience in urban areas’ (CORFU). The approach adopted in this project aims to quantify the cost-effectiveness of resilience measures and integrative and adaptable flood management plans for different scenarios of relevant drivers: urban development, socio-economic trends and climate changes. It is believed that the way in which the different models are being put together, combined with the variability of conditions in case study areas in Asia and in Europe, will ultimately enable more scientifically sound policies for the management of the consequences of urban flooding. 相似文献