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121.
Guy Beauchamp 《Behavioral ecology and sociobiology》2014,68(9):1473-1479
Animals that forage in groups can produce their own food patches or scrounge the food discoveries of their companions. Mean tactic payoffs are expected to be the same at equilibrium for phenotypically equal foragers. Scrounging is also typically viewed as a risk-averse foraging strategy that provides a more even food intake rate over time. The occurrence of scrounging and the payoffs from different foraging modes have rarely been investigated in the field. Over two field seasons, I examined patch sharing in semipalmated sandpipers (Calidris pusilla) foraging on minute food items at the surface of the substrate. Birds could find patches on their own, a producing event, or join the food patches discovered by others, a scrounging event. I found that the average search time per patch did not differ between producing and scrounging but that the average time spent exploiting a patch was reduced nearly by half when scrounging. As a result, the proportion of time spent exploiting a patch, a measure of foraging payoffs, was significantly lower when scrounging. The variance in payoffs was similar for producing and scrounging. When producing their own patches, individuals that scrounged spent the same proportion of time exploiting a patch as those that only produced. However, within the same individuals, the search time for a scrounged patch was longer than the search time for a produced patch. The results show unequal payoffs for producing and scrounging in this system and suggest that low success in finding patches elicited scrounging. 相似文献
122.
H. L. I. Bornett J. H. Guy P.J. Cain 《Journal of Agricultural and Environmental Ethics》2003,16(2):163-186
The European Union welfare standardsfor intensively kept pigs have steadilyincreased over the past few years and areproposed to continue in the future. It isimportant that the cost implications of thesechanges in welfare standards are assessed. Theaim of this study was to determine theprofitability of rearing pigs in a range ofhousing systems with different standards forpig welfare. Models were constructed tocalculate the cost of pig rearing (6–95 kg) in afully-slatted system (fulfilling minimum EUspace requirements, Directive 91630/EEC); apartly-slatted system; a high-welfare,straw-based system (complying with the UK-basedRoyal Society for the Prevention of Cruelty toAnimals, Freedom Food standards) and afree-range system. The models were also used toassess the consequences of potential increasesin space allowance, and to estimate the cost ofrearing pigs under organic standards.The cost of rearing pigs ranged from92.0 p/kg carcass weight (cw) and 94.6 p/kgcw forthe partly-slatted and fully-slatted systems,to 98.8 p/kgcw and 99.3 p/kgcw for the FreedomFood and free-range systems respectively. Whenspace allowance was increased by 60% to levelsin a recent proposal to revise pig welfareDirective (91/630/EEC), the rearing costs wereunchanged for the free-range system but rose by4.6 p/kgcw for the fully-slatted system. Rearingcosts under organic standards were 31% higherthan in the free-range system. These resultssuggest that improved pig welfare can beachieved with a modest increase in costAt present, price premiums received for meatproduced under high welfare systems in the UKoffset the higher costs of production in thesesystems. To ensure profitability in the longterm, it is important that these premiums aremaintained. 相似文献
123.
Claude Amoros Jean -Claude Rostan Guy Pautou Jean -Paul Bravard 《Environmental management》1987,11(5):607-617
The wetland ecosystems occurring within alluvial floodplains change rapidly. Within the ecological successions, the life span of pioneer and transient stages may be measured in several years or decades depending on the respective influences of allogenic (water dynamics, erosion, and deposition) and autogenic developmental processes (population dynamics, eutrophication, and terrestrialization). This article emphasizes the mechanisms that are responsible for the ecosystem changes and their importance to environmental management. Two case studies exemplify reversible and irreversible successional processes in reference to different spatial and temporal scales. On the scale of the former channels, the standing-water ecosystems with low homeostasis may recover their previous status after human action on the allogenic processes. On the scale of a whole reach of the floodplain, erosion and deposition appear as reversible processes that regenerate the ecological successions. The concepts of stability and reversibility are discussed in relation to different spatiotemporal referential frameworks and different levels of integration. The reversible process concept is also considered with reference to the energy inputs into the involved subsystems. To estimate the probability of ecosystem regeneration or the cost of restoration, a concept of degrees of reversibility is proposed. 相似文献
124.
Paul M. Salmon Michael G. Lenné Neville A. Stanton Daniel P. Jenkins Guy H. Walker 《Safety Science》2010,48(10):1225-1235
Despite the provision of various theoretical models and error management methods, error and error-causing conditions remain omnipresent within road transport. This article presents a review of human error models and selected error management approaches, and their applications in a road transport context. The review indicates that such applications, although extant, are limited, and that, compared to other domains, the impact of the models and methods discussed has been only minimal. Reasons for this are discussed, and potential ways in which the models and methods can contribute to road safety are proposed. In conclusion, it is argued that human error models and management methods, although already well integrated within most safety critical domains, still have much to offer to the enhancement of road safety. Further, it is argued that advances in the area, in terms of theoretical and methodological development and validation, are still to be made, and that applications of the error management methods discussed are required to enable such advances. 相似文献
125.
The mechanisms of regulating worker reproduction in bumblebees were studied by direct behavioral observations and by measuring
ovarian development and juvenile hormone (JH) biosynthesis rates in workers under different social conditions. Workers in
the last stage of Bombus terrestris colony development (the competition phase) had the lowest ovarian development and JH biosynthesis rates. Callows introduced
into colonies immediately after queen removal (dequeened colonies) demonstrated a significant increase in ovarian development
before, but not during, the competition phase. These findings differ from the higher ovarian development in colonies during
the competition phase predicted by the prevailing hypothesis that worker reproduction starts in response to a decrease in
queen inhibition. Reproduction of callows housed with dominant workers in small queenless groups was inhibited as in queenright
colonies. This suggests that the reduced ovarian development and JH biosynthesis rates observed in dequeened and normally
developing colonies during the competition phase also reflect inhibition by dominant workers. Thus, two distinct stages of
inhibition of reproduction seem to exist: (1) before the competition phase, when the queen slows down worker ovarian development
and prevents oviposition; (2) during the competition phase, when dominant workers inhibit ovarian development of other workers.
Between these stages there seems to be a temporal “window” of enhanced worker reproductive development. The queen's typical
switch to haploid egg production was not associated with changes in worker ovarian development or JH biosynthesis rates. These
findings suggest that regulation of worker reproduction in B. terrestris is not determined by simple changes in the queen's inhibition capacity or by the sex of offspring and that the worker's role
is more important than previously believed.
Received: 18 March 1998 / Accepted after revision: 18 July 1998 相似文献
126.
Grais RF Coulombier D Ampuero J Lucas ME Barretto AT Jacquier G Diaz F Balandine S Mahoudeau C Brown V 《Disasters》2006,30(3):364-376
Emergencies resulting in large-scale displacement often lead to populations resettling in areas where basic health services and sanitation are unavailable. To plan relief-related activities quickly, rapid population size estimates are needed. The currently recommended Quadrat method estimates total population by extrapolating the average population size living in square blocks of known area to the total site surface. An alternative approach, the T-Square, provides a population estimate based on analysis of the spatial distribution of housing units taken throughout a site. We field tested both methods and validated the results against a census in Esturro Bairro, Beira, Mozambique. Compared to the census (population: 9,479), the T-Square yielded a better population estimate (9,523) than the Quadrat method (7,681; 95% confidence interval: 6,160-9,201), but was more difficult for field survey teams to implement. Although applicable only to similar sites, several general conclusions can be drawn for emergency planning. 相似文献
127.
Ayodeji Ogedengbe Kingsley Achiobu Santiago Scoccimarro Sylvain Brunet Guy Gagnon Michael Fabrik 《International Journal of Green Energy》2020,17(8):521-528
ABSTRACT Sodium sulfate is a common low-value industrial by-product but can be managed using the Glaserite process to convert it into high-value potassium sulfate. The aim of the study is to investigate the potential for implementing this process in an industrial application. Experimental studies were completed to determine the yield and purity of both glaserite and potassium sulfate. Process simulation using SysCAD was utilized to optimize a two-stage glaserite process to produce potassium sulfate. Comparison of experimental and simulated data was made to validate the simulator’s results, finding the AAD in solid and liquid phase for glaserite production to be 6.9% and 5.7%, respectively, and for potassium sulfate to be 5.7% and 2.3%, respectively. For a process treating seven MT/hr of Na2SO4, a KCl feed strategy of 3.0 MT/hr to the glaserite reactor and 4.5 MT/hr to the K2SO4 reactor was found to maximize yield and minimize water demand. It was also found that ambient temperatures were preferred for the K2SO4 reactor and that K2SO4 yield suffered significantly under certain conditions when the glaserite reactor operated at 50°C or above. 相似文献
128.
John Munthe Eva Brorström-Lundén Magnus Rahmberg Leo Posthuma Rolf Altenburger Werner Brack Dirk Bunke Guy Engelen Bernd Manfred Gawlik Jos van Gils David López Herráez Tomas Rydberg Jaroslav Slobodnik Annemarie van Wezel 《Environmental Sciences Europe》2017,29(1):13
Background
This paper describes a conceptual framework for solutions-focused management of chemical contaminants built on novel and systematic approaches for identifying, quantifying and reducing risks of these substances.Methods
The conceptual framework was developed in interaction with stakeholders representing relevant authorities and organisations responsible for managing environmental quality of water bodies. Stakeholder needs were compiled via a survey and dialogue. The content of the conceptual framework was thereafter developed with inputs from relevant scientific disciplines.Results
The conceptual framework consists of four access points: Chemicals, Environment, Abatement and Society, representing different aspects and approaches to engaging in the issue of chemical contamination of surface waters. It widens the scope for assessment and management of chemicals in comparison to a traditional (mostly) perchemical risk assessment approaches by including abatement- and societal approaches as optional solutions. The solution-focused approach implies an identification of abatement- and policy options upfront in the risk assessment process. The conceptual framework was designed for use in current and future chemical pollution assessments for the aquatic environment, including the specific challenges encountered in prioritising individual chemicals and mixtures, and is applicable for the development of approaches for safe chemical management in a broader sense. The four access points of the conceptual framework are interlinked by four key topics representing the main scientific challenges that need to be addressed, i.e.: identifying and prioritising hazardous chemicals at different scales; selecting relevant and efficient abatement options; providing regulatory support for chemicals management; predicting and prioritising future chemical risks. The conceptual framework aligns current challenges in the safe production and use of chemicals. The current state of knowledge and implementation of these challenges is described.Conclusions
The use of the conceptual framework, and addressing the challenges, is intended to support: (1) forwarding sustainable use of chemicals, (2) identification of pollutants of priority concern for cost-effective management, (3) the selection of optimal abatement options and (4) the development and use of optimised legal and policy instruments.129.
Waha Katharina Krummenauer Linda Adams Sophie Aich Valentin Baarsch Florent Coumou Dim Fader Marianela Hoff Holger Jobbins Guy Marcus Rachel Mengel Matthias Otto Ilona M. Perrette Mahé Rocha Marcia Robinson Alexander Schleussner Carl-Friedrich 《Regional Environmental Change》2017,17(6):1623-1638
Regional Environmental Change - The Middle East and North Africa (MENA) region emerges as one of the hot spots for worsening extreme heat, drought and aridity conditions under climate change. A... 相似文献
130.
An enhanced dual coil 2,4-dinitrophenylhydrazine (DNPH) derivatization method (dual coil/DNPH) allowed the quantitative determination
of formaldehyde (HCHO) in ambient air. In this method, traceable HCHO was collected using a coil sampler connected in series
and lacking a long sampling tube. It was then analyzed using liquid chromatography followed by UV detection of the DNPH derivatives.
The method is based on the reaction of formaldehyde with DNPH to produce 2,4-dinitrophenylhydrazone. The detection limits
(3σ) were 0.10–0.40 ppbv with a precision ranging from 0.84 to 4.09% RSD. The results of dual coil/DNPH and conventional DNPH
cartridge methods were generally well correlated: HCHO (dual coil/DNPH) = 0.97 (±0.13) vs. HCHO (DNPH Cartridge) + 0.33 (±0.33),
r = 0.82. The dual coil/DNPH method was used to measure gaseous HCHO in the atmosphere of Metropolitan Seoul during the summer
2000 and 2001, and in Gwangju during the fall of 2001 and 2002. The daytime mean concentration of HCHO was 4.52 (±5.69) and
3.21 (±1.27) ppbv in Metropolitan Seoul for 10–12 August 2000 and 29–31 May 2001, respectively, and 1.73 (±0.98), 3.04 (±2.25),
2.70 (±1.70), and 2.01 (±2.28) ppbv in Gwangju City during 22–27 September 2001, 17–24 October 2001, 9–13 October 2002, and
28 October to 2 November 2002, respectively. The HCHO in Seoul from 10–12 August 2000 was mainly the result of photochemical
processes, while direct emissions from vehicles and long-range transport of air from China contributed during 29–31 May 2001.
During 22–27 September 2001, 17–24 October 2001, and 9–13 October 2002 in Gwangju, the HCHO came primarily from photochemical
processes, although some air affected by biomass burning admixed in the late afternoon. The increase in the HCHO concentration
on 20 October 2001 and from 28 October to 2 November 2002 was attributed mainly to direct emissions from biomass burning in
farmland near the measurement site. 相似文献