全文获取类型
收费全文 | 1337篇 |
免费 | 78篇 |
国内免费 | 130篇 |
专业分类
安全科学 | 212篇 |
废物处理 | 17篇 |
环保管理 | 392篇 |
综合类 | 303篇 |
基础理论 | 338篇 |
环境理论 | 1篇 |
污染及防治 | 85篇 |
评价与监测 | 91篇 |
社会与环境 | 66篇 |
灾害及防治 | 40篇 |
出版年
2023年 | 18篇 |
2022年 | 21篇 |
2021年 | 43篇 |
2020年 | 37篇 |
2019年 | 36篇 |
2018年 | 22篇 |
2017年 | 41篇 |
2016年 | 53篇 |
2015年 | 49篇 |
2014年 | 40篇 |
2013年 | 85篇 |
2012年 | 46篇 |
2011年 | 94篇 |
2010年 | 68篇 |
2009年 | 103篇 |
2008年 | 68篇 |
2007年 | 69篇 |
2006年 | 89篇 |
2005年 | 63篇 |
2004年 | 51篇 |
2003年 | 50篇 |
2002年 | 50篇 |
2001年 | 35篇 |
2000年 | 35篇 |
1999年 | 20篇 |
1998年 | 22篇 |
1997年 | 18篇 |
1996年 | 17篇 |
1995年 | 16篇 |
1994年 | 15篇 |
1993年 | 11篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1981年 | 9篇 |
1980年 | 11篇 |
1979年 | 13篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1973年 | 6篇 |
1972年 | 8篇 |
1971年 | 7篇 |
排序方式: 共有1545条查询结果,搜索用时 234 毫秒
991.
Witold F. Krajewski Karol L. Krajewski 《Journal of the American Water Resources Association》1989,25(2):391-399
ABSTRACT: The problem of real-time quality control of streamflow data is addressed. Five methods are investigated via a Monte-Carlo simulation experiment based on streamflow data from Bird Creek basin in Oklahoma. The five methods include three deterministic approaches and two statistical approaches. The relative performance of the investigated methods is evaluated under hypothesized random mechanism generating isolated outliers. The deterministic method based on streamflow gradient analysis and the statistical method based on forecast residual analysis perform best in detecting such outliers. 相似文献
992.
Fjeld RA Serkiz SM McGinnis PL Elci A Kaplan DI 《Journal of contaminant hydrology》2003,67(1-4):79-94
A conceptual model is proposed to explain the transport behavior of plutonium in laboratory columns packed with a sandy coastal soil from the U.S. Department of Energy (DOE)'s Savannah River Site. The column transport experiments involved the introduction of a finite step input of plutonium, predominately in the +5 oxidation state, into the columns followed by elution with a low-carbonate solution of 0.02 M NaClO4 at pH 3, 5, and 8. Total plutonium concentrations were measured in the effluent as a function of time. These elution profiles suggest at least two distinct physical/chemical forms of plutonium, each with a different mobility. To explain the observed behavior, the following conceptual model was evaluated: [1] equilibrium partitioning of plutonium (V) and plutonium (IV) between the aqueous and sorbed phases as defined by pH-dependent, oxidation-state specific distribution coefficients and [2] kinetic reduction of plutonium (V) to plutonium (IV) in the sorbed phase. The conceptual model was applied to the column experiments through a one-dimensional advective/dispersive mathematical model, and predictions of the mathematical model were compared with the experimental data. Overall, the model was successful in predicting some of the major features observed in the experiments. It also yielded quantitative estimates of the rate constant for surface mediated reduction of plutonium (V) to plutonium (IV) that were of the same order (10(-4) to 10(-5) s(-1)) as those calculated from batch data both for this soil and for goethite. 相似文献
993.
Removal of NAPLs from the unsaturated zone using steam: prevention of downward migration by injecting mixtures of steam and air 总被引:1,自引:0,他引:1
Steam injection for remediation of porous media contaminated by nonaqueous phase liquids has been shown to be a potentially efficient technology. There is, however, concern that the technique may lead to downward migration of separate phase contaminant. In this work, a modification of the steam injection technology is presented, where a mixture of steam and air was injected. In two-dimensional experiments with unsaturated porous medium contaminated with nonaqueous phase liquids, it was demonstrated how injection of pure steam lead to severe downward migration. Similar experiments, where steam and air were injected simultaneously, resulted in practically no downward migration and still rapid cleanup was achieved. The processes responsible for the prevention of downward migration when injecting steam-air mixtures were analyzed using a nonisothermal multiphase flow and transport model. Hereby, three mechanisms were identified and it was demonstrated how the effectiveness of these mechanisms depended on the air-to-steam mixing ratio. 相似文献
994.
Optimization of the Resources Management in Fighting Wildfires 总被引:1,自引:0,他引:1
Wildfires lead to important economic, social, and environmental losses, especially in areas of Mediterranean climate where
they are of a high intensity and frequency. Over the past 30 years there has been a dramatic surge in the development and
use of fire spread models. However, given the chaotic nature of environmental systems, it is very difficult to develop real-time
fire-extinguishing models. This article proposes a method of optimizing the performance of wildfire fighting resources such
that losses are kept to a minimum. The optimization procedure includes discrete simulation algorithms and Bayesian optimization
methods for discrete and continuous problems (simulated annealing and Bayesian global optimization). Fast calculus algorithms
are applied to provide optimization outcomes in short periods of time such that the predictions of the model and the real
behavior of the fire, combat resources, and meteorological conditions are similar. In addition, adaptive algorithms take into
account the chaotic behavior of wildfire so that the system can be updated with data corresponding to the real situation to
obtain a new optimum solution. The application of this method to the Northwest Forest of Madrid (Spain) is also described.
This application allowed us to check that it is a helpful tool in the decision-making process. 相似文献
995.
Urban waste recycling behavior: antecedents of participation in a selective collection program 总被引:1,自引:0,他引:1
ABSTRACT/
The aim of this study is to analyze the antecedents of urban waste recycling behavior. To achieve this goal, a concrete urban
waste management program was chosen. The study focuses on the Selective Collection Program (SCP) in Zaragoza, a medium-sized
city in northeastern Spain. The research starts with a conceptual model in which the variables that potentially affect recycling
behavior can be classified into two groups: incentives and barriers. Moreover, the sociodemographic characteristics of the
individuals are included in our study. Given that the proposed model requires specification of latent variables or constructs,
the analysis is based on the Structural Equation Models (SEM) methodology. The results revealed that environmental awareness,
knowledge of the environmental impact of urban waste, and the positive perception of management by local government exercise
a positive effect on individual recycling behavior, while perceived personal difficulties (space and time availability) and
distance to and from the container have a negative effect. As regards sociodemographic variables, this study found that annual
family income sustains a negative relationship with recycling behavior, while age maintains a positive one. The results obtained
clearly show the important role that the public authorities play, especially municipal governments, in achieving the waste
recycling objectives established in accordance with international legislation. 相似文献
996.
Soil pollution data is also strongly scattering at small scale. Sampling of composite samples, therefore, is recommended for pollution assessment. Different statistical methods are available to provide information about the accuracy of the sampling process. Autocorrelation and variogram analysis can be applied to investigate spatial relationships. Analysis of variance is a useful method for homogeneity testing. The main source of the total measurement uncertainty is the uncertainty arising from sampling. The sample mass required for analysis can also be estimated using an analysis of variance. The number of increments to be taken for a composite sample can be estimated by means of simple statistical formulae. Analytical results of composite samples obtained from different fusion procedures of increments can be compared by means of multiple mean comparison. The applicability of statistical methods and their advantages are demonstrated for a case study investigating metals in soil at a very small spatial scale. The paper describes important statistical tools for the quantitative assessment of the sampling process. Detailed results clearly depend on the purpose of sampling, the spatial scale of the object under investigation and the specific case study, and have to be determined for each particular case. 相似文献
997.
Lead removal from contaminated water using mineral adsorbents 总被引:3,自引:0,他引:3
M. N. Rashed 《The Environmentalist》2001,21(3):187-195
This study records experiments undertaken to determine the suitable conditions for the use of naturally occurring minerals (talc, chalcopyrite and barite) as an adsorbent for the removal of lead ions from liquid wastes. The adsorption of lead ions from solutions containing different initial lead concentrations (50, 100, 200, 400, 600, 800 and 1000 mg l–1 Pb as lead nitrate) using different size fractions (<63 m, 63–150 m) of talc, chalcopyrite and barite at different pH (3, 5, 7 and 9) and different adsorption times (24, 48, 72 and 96 hr) was examined. The results revealed that of the studied minerals, the chalcopyrite fraction at 63–150 m showed the highest adsorption capacity. The adsorption data of Pb ions was also analyzed with the help of the Langmuir and Freundlich models to evaluate the mechanistic parameters associated with the adsorption process. The adsorption isotherms obtained from the Langmuir and Freundlich equations were generally linear and the adsorption of Pb by the studied minerals was correlated with the adsorption maximum and binding energy constant of the Langmuir equation and equilibrium partition constant and binding partition coefficient of the Freundlich equation. It was concluded that the equilibrium time of adsorption was 72 hr at an optimum pH from 7 to 9. This technique might be successfully used for the removal of lead ions from liquid industrial wastes and wastewater. 相似文献
998.
This paper presents a dynamic framework for environmental assessment when the system under study is undergoing successional
change. Successional differences between sites for which one wishes to detect a difference because of a treatment are essentially
confounding factors. We show how successional changes over the study period or resulting from differences in study site plot
ages can be factored out by developing a null model of expected behavior over time. The null model for change in state with
time is characterized in terms of a stochastic envelope around a nominal trajectory. Specific tests for the detection of trends
associated with succession are described and illustrated on example data. It is concluded that the methods developed work
particularly well for laboratory microcosm data. 相似文献
999.
H. Tong B. Thanoon G. Gudmundsson 《Journal of the American Water Resources Association》1985,21(4):651-662
ABSTRACT: This paper reports our experience in building time series models which connect the flows in two Icelandic rivers with the meteorological variables of precipitation and temperature. Two rivers with different hydrological characteristics were studied. In areas where precipitation may be either in the form of rain or snow linear models are inadequate to describe the relationship between the river and the meteorological variables. The methodology of threshold models recently developed seems to be well suited for taking into account the sharp difference in the relationship according to whether it is freezing or not. The possibility of identifying an alternative threshold variable is also explored. 相似文献
1000.
Tzay-Rong Jenq Marvin L. Granstrom Shing-Fu Hsueh Christopher G. Uchrin 《Journal of the American Water Resources Association》1984,20(4):511-520
ABSTRACT A linear programming model to assess the cost-effectiveness of appropriate point and nonpoint phosphorus control measures was constructed for Carnegie Lake, an eutrophic lake located in Mercer County, New Jersey. The resultant model was tested for present and future conditions. Feasible solutions were obtained only after significant relaxation of receiving water quality standards. The high levels of point source treatment required to meet the in-stream water quality standards and the mesotrophic loading conditions suggest that a source control solution may not be feasible. 相似文献