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831.
A coupled three-dimensional hydrodynamic–ecological model was used for the assessment of water quality in Narva Bay during one biologically active season. Narva Bay is located in the south-eastern Gulf of Finland. Narva River with a catchment’s area covering part of Russia and Estonia discharges water and nutrients to Narva Bay. The ecological model includes phytoplankton carbon, nitrogen and phosphorus, chlorophyll a, zooplankton, detritus carbon, nitrogen and phosphorus, inorganic nitrogen, inorganic phosphorus and dissolved oxygen as state variables. Both the hydrodynamic and ecosystem models were validated using a limited number of measurements. The hydrodynamic model validation included comparison of time series of currents and temperature and salinity profiles. The ecological model results were compared with the monitoring data of phytoplankton biomass, total nitrogen and phosphorus and dissolved oxygen. The comparison of hydrodynamic parameters, phytoplankton biomass, surface layer total phosphorus and dissolved oxygen and near-bottom layer total nitrogen was reasonable. Time series of spatially mean values and standard deviations of selected parameters were calculated for the whole Narva Bay. Combining model results and monitoring data, the characteristic concentrations of phytoplankton biomass, total nitrogen and phosphorus and near-bottom dissolved oxygen were estimated. Phytoplankton biomass and total phosphorus showed seasonal variations, of 0.6–1.1 and 0.022–0.032 mg/l, respectively, during spring bloom, 0.1–0.3 and 0.015–0.025 mg/l in summer and 0.2–0.6 and 0.017–0.035 mg/l during autumn bloom. Total nitrogen and near-bottom oxygen concentrations were rather steady, being 0.25–0.35 and 2–6 mg/l, respectively. The total nitrogen and phosphorus concentrations show that according to the classification of Estonian coastal waters, Narva Bay water belongs to a good water quality class. 相似文献
832.
The purpose of the present study was to evaluate the groundwater contamination due to the construction and operation of the
municipal landfill of Amari, Rethymno, Crete. The groundwater flow and leachate transport in the vadose and saturated zones
were studied and simulated, using three different models: the one-dimensional groundwater flow and contaminant transport model
for the vadose zone Pesticide Root Zone Model (PRZM-3), the Geographical Information System (GIS) Argus ONE and the three-dimensional
groundwater flow and contaminant transport model Princeton Transport Code (PTC). The simulation time was 30 and 20 years,
and the results obtained, according to the models and the existing hydrogeological conditions, were very encouraging and reassuring
about the groundwater quality of the broad region. 相似文献
833.
Sonja Peterson 《Environmental Modeling and Assessment》2006,11(1):1-17
The analysis of climate change is confronted with large uncertainties that need to be taken into account to arrive at meaningful
policy recommendations. The main contribution of economics to this interdisciplinary task is to provide formal frameworks
and techniques for analyzing climate policy in the context of uncertainty. This paper will give an overview of existing approaches
and findings to provide a broad picture of what economics can contribute to the debate. 相似文献
834.
Abbas Al-Omari Manar Fayyad Abed Abdel Qader 《Environmental Modeling and Assessment》2005,9(4):245-252
A mathematical model that expresses Total trihalomethane (TTHM) concentration in terms of initial chlorine concentration, total organic carbon, bromide ion concentration, contact time, and pH is developed for Zai water treatment plant which supplies water to Jabal Amman. The developed mathematical model is for constant temperature of 20°C. To adjust model calculated TTHM concentrations for temperatures other than 20°C, another mathematical model that expresses TTHM growth rate as function of temperature is also developed. To test the ability of the two developed models in predicting TTHM concentrations throughout water supplies, a sampling program that aimed at measuring TTHM concentrations in addition to the predictors in the two developed mathematical models namely; chlorine concentration, bromide ion concentration, total organic carbon, temperature and pH throughout Jabal Amman water supply was conducted. The two developed mathematical models and WaterCad, which was used to determine water age, were used to predict TTHM concentrations throughout Jabal Amman water supply. Predicted TTHM concentrations were compared to actual TTHM concentrations measured during the sampling program. Results showed that there is good agreement between measured and, calculated TTHM concentrations, which means that the method presented in this paper, can be used to obtain good estimates of TTHM concentrations throughout networks. 相似文献
835.
J. E. Sickles II J. C. Suggs L. M. Vorburger 《Environmental monitoring and assessment》2000,65(3):485-502
Ozone levels at Clean Air Status andTrends Network (CASTNet) and nearby rurally-designatedState and Local Air Monitoring Stations (SLAMS) siteslocated in the eastern United States (U.S.) arecompared using daily indicators (i.e., maximum, range,and SUM06) based on hourly O3 measurements. Comparisons are also made using monthly and summertimethree-month SUM06 determinations aggregated from dailydata. Comparison of O3 indicators at the pairedCASTNet-SLAMS sites generally shows better agreementfor O3 maximum than for range or SUM06. Thehighest correlation of daily O3 indicators occursfor paired sites that are separated by less than 100miles, and the correlation diminishes with increasingseparation distance. Correlation coefficients exceed0.70 in 49% of the comparisons of maximum, in23% of range comparisons and in 5% ofSUM06 comparisons, suggesting that substitution ofSLAMS for CASTNet O3 measurements would fail tocapture a substantial amount of the variability inO3 indicators present at the CASTNet sites. Correlations of O3 indicators at CASTNet andpaired nearby SLAMS sites are 0.80 in a relativelysmall number of cases. Despite the high correlationin even these cases, O3 behavior at paired sitesis not identical and shows systematic differences thatare reflected in the O3 minimum, hourly averageconcentrations, and the monthly and three-month SUM06. Ozone measurements at nearby rurally-designated SLAMSsites may not capture the `rural' nature of the airquality being monitored at CASTNet sites and, in mostcases, may not be sufficiently representative of theconcentration at CASTNet sites to permit O3measurements at SLAMS sites to be used in lieu ofmeasurements at CASTNet sites. As a result, if ruralO3 concentration data are needed, then O3monitoring at carefully chosen, rurally representativesites is recommended. 相似文献
836.
Many governments use technology incentives as an important component of their greenhouse gas abatement strategies. These carrots are intended to encourage the initial diffusion of new, greenhouse-gas-emissions-reducing technologies, in contrast to carbon taxes and emissions trading which provide a stick designed to reduce emissions by increasing the price of high-emitting technologies for all users. Technology incentives appear attractive, but their record in practice is mixed and economic theory suggests that in the absence of market failures, they are inefficient compared to taxes and trading. This study uses an agent-based model of technology diffusion and exploratory modeling, a new technique for decision-making under conditions of extreme uncertainty, to examine the conditions under which technology incentives should be a key building block of robust climate change policies. We find that a combined strategy of carbon taxes and technology incentives, as opposed to carbon taxes alone, is the best approach to greenhouse gas emissions reductions if the social benefits of early adoption sufficiently exceed the private benefits. Such social benefits can occur when economic actors have a wide variety of cost/performance preferences for new technologies and either new technologies have increasing returns to scale or potential adopters can reduce their uncertainty about the performance of new technologies by querying the experience of other adopters. We find that if decision-makers hold even modest expectations that such social benefits are significant or that the impacts of climate change will turn out to be serious then technology incentive programs may be a promising hedge against the threat of climate change. 相似文献
837.
Miroslav Jicha Jiri Pospisil Jaroslav Katolicky 《Environmental monitoring and assessment》2000,65(1-2):343-351
A 3-D Eulerian-Lagrangian approach to moving vehicles is presented that takes into account the traffic induced flow rate and turbulence. The method is applied to pollutants dispersion in a street canyon. The approach is based on CFD calculations using Eulerian approach to the continuous phase and Lagrangian approach to the "discrete phase" of moving objects - vehicles. A commercial CFD code StarCD was used into which the Lagrangian model was integrated. As an example a street canyon is taken into consideration. It has the length of 50 m and the aspect ratio of 1.27. The speed of wind was assigned values of 4, 7 and 12 m/s at the altitude of 300 m. The total height of the domain is 115 m. In the study different traffic situations are considered, namely one-way and two-way traffic with different traffic rates per lane. The predictions show that different traffic situations affect pollutants dispersion in the street canyon and that there are also differences in the pollutants dispersion in case of one- and two-way traffic. 相似文献
838.
839.
Diamando Vlachogiannis Spyros Andronopoulos Artemis Passamichali Nikos Gounaris John G. Bartzis 《Environmental monitoring and assessment》2000,65(1-2):41-48
This study concentrated on the effects of Biogenic Volatile Organic Compounds (BVOC) emissions on ozone (O3) in an area of the Eastern Spain on June 12, 1997, a day characterised by sea breeze. Simulation of meteorology was performed with the three-dimensional model ADREA-I. Comparisons of the model results with observations have revealed overall a good agreement in temperature and wind velocity. Two runs were performed with UAM-IV for the photochemical calculations. The first simulated the effects of the anthropogenic emissions only (run A) and the second the combined effects of anthropogenic and biogenic emissions, (run B). Comparisons of the model O3 concentrations with measurements showed a general agreement with the experimental data. Discrepancies between the calculated results and the observations during the early morning hours could be attributed to inaccuracies in nitrogen oxides (NOx) from the anthropogenic emissions inventory. Comparisons between runs A and B yielded differences up to 30% in the morning, over inland areas. It was deduced that the inclusion of BVOC in total emissions could result in an increase or decrease of tropospheric O3, depending on the available amounts of anthropogenic emissions. 相似文献
840.
C. Schlumpf J. Behringer G. Dürrenberger C. Pahl-Wostl 《Environmental Modeling and Assessment》1999,4(1):1-12
Participatory Integrated Assessment (PIA) is an approach which aims at developing methods which allow to combine evaluations
of experts and lay people in the field of Integrated Assessment. Thus, policy recommendations derived from PIA exercises are
informed by scientific judgments and by valuations of “non-scientists”. For any PIA methodology the provision of insights,
facts and figures about the policy problem at hand is crucial.
In this paper we describe a PIA methodology which combines the social science research instrument “focus group” with a specific
computer information tool, the “Personal CO2 Calculator” (PCC). The tool supports citizens in discussing and recommending measures on climate change policy. Based on
our experiences, we plead for information instruments that are tuned to and assist concrete target groups with their specific
interests. This helps that policy recommendations derived from PIA exercises are based on both scientific knowledge as well
as citizens' and stakeholders' policy preferences.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献