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51.
Summary. Young larvae of Adalia bipunctata search an area more intensively when exposed to the odour from other larvae feeding on aphids than when exposed only to the
odour of aphids. In an olfactometer young larvae were significantly attracted either to the odour of crushed aphids or larvae
feeding on aphids, but not to that of aphids, larvae, larvae plus aphids or larvae feeding on an artificial diet. That is,
the change in searching behaviour appears in response to a volatile released by aphids when attacked. The odour released by
crushed aphids is made up entirely of aphid alarm pheromone, β-farnesene. It is likely that the adaptive significance of this
response is that it increases the ability of larvae to locate larvae that have already caught prey. By sharing the aphid kill
of another larva it is likely that a first instar ladybird larva greatly increases its probability of surviving to the next
instar. It is suggested that this social feeding is facilitated by egg clustering, which also may additionally account for
why aphidophagous ladybirds lay their eggs in clusters.
Received 28 February 2000; accepted 24 March 2000 相似文献
52.
In this paper we introduce a new method of analysing the relationship between nitrogen dioxide (NO2) and oxides of nitrogen (NOx) concentrations using data from the UK National Air Quality Archive. The study includes analyses of measurements from two different types of site in London, a kerbside site: Cromwell Rd, and three background sites: Bridge Place, London Bloomsbury and West London, over several years (1991–7). The data in some years showed that hourly NO2 concentrations exceeded the UK Standard of 150 ppb. Data were binned, averaged, and polynomials fitted at each site. Analysis of the resulting polynomials was used to estimate reductions in NOx emission required to achieve the National Air Quality Strategy Objective. Examination of the empirical ratio NO2:NOx (the 'yield') gives an indication of the sensitivity of the NO2 to NOx controls and the amount of NO2 that would arise from modelled values of total oxides of nitrogen. The response of NO2 to emission changes is very non-linear, implying 30–45% controls on NOx may be required. 相似文献
53.
Farwell AJ Vesely S Nero V Rodriguez H McCormack K Shah S Dixon DG Glick BR 《Environmental pollution (Barking, Essex : 1987)》2007,147(3):540-545
The growth of transgenic canola (Brassica napus) expressing a gene for the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase was compared to non-transformed canola exposed to flooding and elevated soil Ni concentration, in situ. In addition, the ability of the plant growth-promoting bacterium Pseudomonas putida UW4, which also expresses ACC deaminase, to facilitate the growth of non-transformed and transgenic canola under the above mentioned conditions was examined. Transgenic canola and/or canola treated with P. putida UW4 had greater shoot biomass compared to non-transformed canola under low flood-stress conditions. Under high flood-stress conditions, shoot biomass was reduced and Ni accumulation was increased in all instances relative to low flood-stress conditions. This is the first field study to document the increase in plant tolerance utilizing transgenic plants and plant growth-promoting bacteria exposed to multiple stressors. 相似文献
54.
Chronic toxicity of As, Co, Cr and Mn to Hyalella azteca can be described using a saturation-based mortality model relative to total-body or water metal concentration. LBC25s (total-body metal concentrations resulting in 25% mortality in 4 weeks) were 125, 103, 152 and 57,900 nmol g-1 dry weight for As, Co, Cr and Mn respectively. LC50s (metal concentrations in water resulting in 25% mortality in 4 weeks) were 5600, 183, 731, and 197,000 nmol L-1, respectively. A hormesis growth response to As exposure was observed. Growth was a more variable endpoint than mortality for all four toxicants; however, confidence limits based on growth and mortality all overlapped, except Cr which had no effect on growth. Mn toxicity was greater in glass test containers compared to plastic. Bioaccumulation of As, Co, Cr, and Mn was strongly correlated with, and is useful for predicting, chronic mortality. 相似文献
55.
56.
东非地区的海洋保护区:它们取得了多大的成功? 总被引:3,自引:0,他引:3
Julius Francis Agneta Nilsson Dixon Waruinge 《Ambio-人类环境杂志》2002,31(7):503-511
本文探讨了东非地区海洋保护区(MPA)及其所包含的珊瑚礁的管理。这一地区包括科摩罗、肯尼亚、马达加斯加、毛里求斯、莫桑比克、坦桑尼亚以及塞舌尔。 相似文献
57.
Robert K. Dixon 《Mitigation and Adaptation Strategies for Global Change》2007,12(3):325-341
Performance reliability advances and cost reductions have been achieved with hydrogen and fuel cell technologies in both the
transportation and distributed energy sectors. This paper reviews the status of hydrogen and fuel cell technologies, identifies
key business and policy drivers for the hydrogen economy, critically examines key barriers to implementing the hydrogen economy,
identifies and discusses key national initiatives to advance the hydrogen economy, and identifies and discusses key intergovernmental
initiatives and activities to advance the hydrogen economy. Hydrogen and fuel cell technology advances, coupled with a reduction
in costs and improvements in performance reliability, present new opportunities for developed and developing countries to
achieve energy, economic and environmental security. Substantial national research and development investments in hydrogen
production, storage, transport, end-use technologies (e.g., fuel cells), safety and public education underscore future opportunities.
Intergovernmental bodies such as Asia Pacific Economic Cooperation (APEC), International Energy Agency (IEA) and the International
Partnership for the Hydrogen Economy (IPHE) provide a multilateral framework for development of a global hydrogen economy.
While the pathway forward for the hydrogen economy is precarious alternative energy options offer substantially fewer public
benefits. 相似文献
58.
The global carbon cycle and climate change: responses and feedbacks from below-ground systems 总被引:3,自引:0,他引:3
According to most global climate models, a continued build-up of CO2 and other greenhouse gases will lead to significant changes in temperature and precipitation patterns over large parts of the Earth. Below-ground processes will strongly influence the response of the biosphere to climate change and are likely to contribute to positive or negative biospheric feedbacks to climate change. Current global carbon budgets suggest that as much as 2000 Pg of carbon exists in soil systems. There is considerable disagreement, however, over pool sizes and flux (e.g. CO2, CH4) for various ecosystems. An equilibrium analysis of changes in global below-ground carbon storage due to a doubled-CO2 climate suggests a range from a possible sink of 41 Pg to a possible source of 101 Pg. Components of the terrestrial biosphere could be managed to sequester or conserve carbon and mitigate accumulation of greenhouse gases in the atmosphere. 相似文献
59.
Summary The purpose of this paper is to examine subjects to show the nature and limit of interdisciplinary communication in existing environmental programmes in US graduate schools. Ultimately, this analysis may provide more effective communication with the general public. Following comparative historical reviews of both the sciences and the human activity for environmental protection, and a content analysis of empirical documents used by the public, a mushroom computer model has been produced. This model is based on organizational behaviour theory and contains the following 15 subjects which were originally introduced before the lack of communication resulting from curriculum failure in the 19th century: philosophy, politics, economics, architecture, sociology, biology, medicine, agriculture, ecology, public health, mathematics, physics, chemistry, geology, statistics. The subjects should foster effective communication with the general public, leading to more effective environmental protection.Dr Hong S. Kim is at the Environmental Studies Program, California State University, Fullerton, USA. He received a PhD from the Administration and Management Program at Walden University, Minneapolis, Minnesota, USA. His numerous papers are focused on environmental pollution analysis, environmental impact assessment, environmental management, and environmental law. He has written a book entitledEnvironmentology which is forthcoming.Dr James P. Dixon is the Chairperson of Health Services at Walden University, Minneapolis, Minnesota 55401, USA. He was recently Professor of the Department of Policy and Administration at the University of North Carolina at Chapel Hill, USA. He was also past President of Antioch College (1959–1975). His many publications are concentrated in the areas of organizational development, public health and preventive medicine, and administration of human service organizations. 相似文献
60.
L.C. Alves U. Borgmann D.G. Dixon 《Environmental pollution (Barking, Essex : 1987)》2009,157(8-9):2239-2247
The kinetics of uptake and the effect of body size on uranium (U) bioaccumulation and toxicity to Hyalella azteca exposed to water-only U concentrations in soft water were evaluated. The effect of body size on U bioaccumulation was significant with a slope of ?0.35 between log body concentration and log body mass. A saturation kinetic model was satisfactory to describe the uptake rate, elimination rate and the effect of gut-clearance on size-corrected U bioaccumulation in H. azteca. The one-week lethal water concentrations causing 50% mortality for juvenile and adult H. azteca were 1100 and 4000 nmol U/L, respectively. The one-week lethal body concentration causing 50% mortality was 140 nmol U/g for juvenile H. azteca and 220 nmol U/g for adult H. azteca. One-week bioaccumulation studies that properly account for body-size and gut-clearance times can provide valuable data on U bioavailability and toxicity in the environment. 相似文献