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41.
Landscape fragmentation affects wildlife population viability, in part, through the effects it has on individual dispersal. In addition, some forms of human disturbance impinge on dispersal without physically fragmenting habitats. Here, we use the term "landscape resistance" to capture constraints to dispersal that cannot be linked directly to fragmentation. The extent to which landscape resistance can influence population persistence is not well understood. Agricultural development over the past 60?years has resulted in considerable habitat fragmentation in the Riding Mountain National Park (RMNP) region in southwestern Manitoba, Canada. We examined how park boundaries, roads outside park boundaries and negative human attitudes have altered dispersal success and population persistence. We examined whether stochastic disturbance, representing infectious disease epidemics, further reduced long-term population persistence for various scenarios. Finally, we assessed whether the simultaneous occurrence of the three features had additive effects. We simulated dispersal using HexSim, a spatially explicit individual-based population model, parameterised with data on wolves (Canis lupus) in the RMNP region. Simulations that separately accounted for negative human attitudes and roads outside the park boundaries exhibited lower mean population size than those that ignored these details. Increasing deflection from park boundaries did not appear to have significant impacts. Our results did not indicate the presence of additive effects, and scenarios incorporating all three features had similar results as that of roads. Stochastic disturbance further reduced mean population size. Our results do illustrate how less-visible human disturbances (i.e. those that do not clearly alter landscape characteristics) can significantly limit dispersal and population persistence.  相似文献   
42.
High genetic diversity is important for the functioning of large insect societies. Across the social Hymenoptera (ants, bees, and wasps), species with the largest colonies tend to have a high colony-level genetic diversity resulting from multiple queens (polygyny) or queens that mate with multiple males (polyandry). Here we studied the genetic structure of Trigona spinipes, a stingless bee species with colonies an order of magnitude larger than those of polyandrous honeybees. Genotypes of adult workers and pupae from 43 nests distributed across three Brazilian biomes showed that T. spinipes colonies are usually headed by one singly mated queen. Apart from revealing a notable exception from the general incidence of high genetic diversity in large insect societies, our results reinforce previous findings suggesting the absence of polyandry in stingless bees and provide evidence against the sperm limitation hypothesis for the evolution of polyandry. Stingless bee species with large colonies, such as T. spinipes, thus seem promising study models to unravel alternative mechanisms to increase genetic diversity within colonies or understand the adaptive value of low genetic diversity in large insect societies.  相似文献   
43.
Sustainable development, as it emerged in Agenda 21 from the Rio conference in 1992, will only be meaningful when it touches the lives of ordinary people; then it becomes a reality. Local Agenda 21 (LA21) seeks to achieve that objective. This article assesses the origins of LA21, reviews its social and political significance, and considers its prospects in the light of case study experience emerging from the UK, Germany and Norway, focusing on the role of local government as a major stakeholder in Agenda 21 (A21). The range of response to LA21 has proved to be varied. A successful transformation to a more sustainable world will require visionary political leadership, supportive administrations, networks of experience sharing, alliances with non-governmental organisations and local industry, and effective community mobilisation. All of that, in turn, requires equally supportive economic and social policy backing from national governments. This article will indicate that, not surprisingly, it is the domestic political context, nationally and locally, which in the main determines the speed and nature of response to LA21, now and in the future. By understanding and being aware of these contexts, factors impeding progress towards LA21 may be addressed, whilst at the same time retaining the diversity of response which is an essential part of local sustainability.  相似文献   
44.
45.
The radiation protection community has only recently started the important work of preparedness for long-term post-accidental management of radioactively contaminated areas, like for instance the EC projects STRATEGY, FARMING and EURANOS and the French authorities' CODIRPA and PAREX programmes. There are, however, different views concerning how long a long-term management might last. Based on the Norwegian and former Soviet Union experience after the Chernobyl accident, it is clear that a nuclear accident can entail decades of necessary management and rehabilitation of living conditions. The time period is dependent on a number of factors, e.g. amount of fallout, type of radionuclides, land use of contaminated area, number and density of people affected and available techniques and resources for implementing countermeasures. This paper discusses the management strategy implemented in Norway after the Chernobyl accident, the need for changing strategy over time and the important involvement of affected groups. Careful planning and reflections should be undertaken before actions are taken in the recovery phase, keeping in mind the possibility of decades with problems.  相似文献   
46.
A small but growing body of literature adds to our understanding of the role of team reflexivity (i.e., reflecting upon team functioning) in predicting team performance. Although many studies conclude that reflexivity is an asset for teams, the contingencies of team reflexivity have received far less research attention. In this respect, we argue that team reflexivity may be especially helpful for teams with relatively low performance. Teams that are reflexive tend to learn from previous mistakes, errors, and group processes, which in turn will improve the performance of the team. We propose that this relationship will most likely positively affect learning and final team performance under conditions of relatively poor prior performance. When a team is doing relatively well, the relationship between reflexivity and final team performance will be less clear, as reflexivity and learning is less needed. In a longitudinal study (N = 73 teams), we found support for this idea. As predicted, results indicated that this interaction between team reflexivity and initial team performance on future performance was mediated by team learning. We outline how these findings are important for our understanding of the contingencies of team reflexivity and team performance dynamics. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
47.
With the present paper, we aim to provide new conceptual insights and empirical evidence on ethical leadership contingencies: we analyze under what conditions ethical leadership can positively impact follower discretionary work behaviors (extra effort and helping). We argue that followers vary in terms of their sensitivity toward and processing of moral information, as conveyed by ethical leaders, and that these individual differences determine the strength of the link between ethical leadership and follower discretionary work behaviors. In a multisource study with 135 leader–follower dyads, we examine two prototypical examples of affective and cognitive individual differences that involve a heightened inclination toward morality: follower moral emotions and follower mindfulness. Our findings indicate that ethical leadership is more strongly related to follower extra effort and helping at higher levels of follower moral emotions and higher levels of follower mindfulness. We discuss the implications of this moral information processing perspective on ethical leadership for research and managerial practice. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
48.
The combined effect of time and temperature on elemental release and speciation from a metal contaminated soil (Master Old Site, MOS) was investigated. The soil was equilibrated at 10, 28, 45, 70 and 90 degrees C for 2 days, 2 weeks, and 2 months in the laboratory. Dissolved organic carbon (DOC), total soluble elements (by ICP), and labile metals (by DPASV) were determined in the filtered (0.22 microm) supernatants. For the samples equilibrated at 90 degrees C, DOC fractions were size fractionated by filtration and centrifugation; a subsample was only centrifuged while another was also filtered through a 0.45 microm filter. Analyses of the supernatants (ICP, DPASV, DOC) were performed on all size fraction subsamples. Dissolved organic carbon (DOC) increased both with temperature and incubation time; however, metal behavior was not as uniform. In general, total soluble metal release (ICP) paralleled the behavior of DOC, increasing with both time and temperature, and confirming the importance of soil organic matter (SOM) in metal retention. Voltammetric analysis (dpasv) of Cu and Zn showed that very little of these metals remains labile in solution due, presumably, to complexation with dissolved organic matter. Labile concentrations of Cd, on the other hand, constituted a significant portion (50%) of total soluble Cd. Copper and Al increased in solution with time (up to 2 months) and temperature up to 70 degrees C; however, at 90 degrees C the soluble concentration declined sharply. The same behavior was observed after equilibration for longer periods of time (550 days) at lower temperatures (23 and 70 degrees C). While concentrations of labile Cu and total soluble Cu and Al increased in the unfiltered samples, the trend remained the same. DPASV analysis showing shifts in labile Cu complexes with temperature and time, together with the results from the unfiltered samples, lead to the hypothesis that Cu was complexing with large polymers that could form at the elevated temperature, and thus be removed from the analyzed solution. It is possible that Cu and Al released by SOM oxidation has re-sorbed or complexed to more recalcitrant organic matter or to mineral phases. Variations in the relative molecular size fractions present within the DOC pool produced by increased time and temperature may influence the element-DOC complexes present in solution and their behavior in soil environments.  相似文献   
49.
If resource consumption is to be reduced through economic “de-growth”, individuals in industrialized countries may have to accept a reduction in their consumption levels. In democratic societies, implementing this process requires the consent of a majority of the population. However, as long as people have high reference levels of consumption, lower consumption will induce feelings of loss, and hence evoke resistance. This paper summarizes recent experimental evidence on some of the factors that determine the utility costs involved in decreasing consumption. The results suggest that the acceptance of economic de-growth would be facilitated if people's material aspirations were moderated, and the extent to which material achievements are emphasized in our daily environment were reduced.An analysis of the financial and economic crisis that developed during 2008 suggests that it will not contribute to either of these points. Rather, by increasing the public's focus on the economic sphere even beyond pre-crisis levels, it may lead to a further decrease in the acceptance of de-growth policies in the population.  相似文献   
50.
新的斯德哥尔摩可持续城市伙伴关系论坛,通过城市和企业间的伙伴关系,将推动可持续性融入城市规划的进程 .开始于 2000年秋季的这个论坛,标志着 1972年联合国环境大会已届 30周年 .全欧各城市的决策者及其选定的企业界同行将应邀参加 .论坛将举办的活动包括各种专题研讨会和在线讨论会 .  相似文献   
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