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171.
In recent years, a significant part of the studies on air pollutants has been devoted to improve statistical techniques for forecasting the values of their concentrations in the atmosphere. Reliable predictions of pollutant trends are essential not only for setting up preventive measures able to avoid risks for human health but also for helping stakeholders to take decision about traffic limitations. In this paper, we present an operating procedure, including both pollutant concentration measurements (CO, SO2, NO2, O3, PM10) and meteorological parameters (hourly data of atmospheric pressure, relative humidity, wind speed), which improves the simple use of neural network for the prediction of pollutant concentration trends by means of the integration of multivariate statistical analysis. In particular, we used principal component analysis in order to define an unconstrained mix of variables able to improve the performance of the model. The developed procedure is particularly suitable for characterizing the investigated phenomena at a local scale.  相似文献   
172.
Flight responses of the aphid parasitoid Aphidius ervi to tomato volatiles have recently demonstrated that different plant stresses can lead to increases in attractiveness for this parasitoid. For example, infestation of tomato plants by the aphid Macrosiphum euphorbiae results in the overexpression of defensive genes, as well as the release of volatile compounds that attract aphid parasitoids. Here, we determine which of the induced compounds elicit a significant electrophysiological response from parasitoid antennae. Compounds shown to be detected at the antennal level were then tested at a range of doses in a wind tunnel assay. A significant electroantennogram response was demonstrated for three compounds, (8S,9R)-(E)-caryophyllene, methyl salicylate, and (Z)-3-hexen-1-ol, over four concentrations. These compounds proved to be significantly attractive in the wind tunnel at a rate not always proportionally dependent upon the dose. The practical implications of these findings are discussed in the framework of sustainable control for pest aphids in agriculture.  相似文献   
173.
It is discussed that the electromagnetic potential can cause the emergence of the coherent structures that in view of their coherence, openness and non-linearity, are able to self-organize and form various hierarchical levels of ecosystems. In the meantime the electromagnetic potential is also the physical agent acting as a messenger in these coherent structures. So it plays the task of reducing the number of independent microstates of a coherent system, becoming a candidate for implementing the concept of negentropy. Electromagnetic potential is shown to be essential for the self-organization and the time evolution of ecosystems, providing the mechanism for their non-locality, complexity and self-consistency (self-maintaining).  相似文献   
174.
Organic wastes have been reported to reduce saturation of the exchange complex by Al in Al-rich acid soils. For 3 years, the main soil fertility properties were studied in plots sown with mixed pasture species. These plots were fertilized with cattle slurry, dairy sludge (DS), or granulated broiler litter (BL) in comparison with mineral fertilizer. Al saturation levels were low after the initial inorganic liming treatment (19.00-33.71%) but tended to rise under all treatments (21.09-61.37%) except BL (8.45-30.98%), which was also associated with the highest average soil pH and the highest average levels of exchangeable Ca2+, Mg2+, and K+. Treatment DS performed similarly to mineral fertilizer in most respects, but it led to greater available P levels. Under the dry conditions of the second and third years of the study, BL and DS treatments were associated with significantly greater forage yields than the other treatments. Under DS treatment, available P levels were too low to allow the maintenance of mixed pasture, clover being eliminated by the less P-dependent species.  相似文献   
175.
Human-caused wildfire risk rating for prevention planning in Spain   总被引:6,自引:0,他引:6  
This paper identifies human factors associated with high forest fire risk in Spain and analyses the spatial distribution of fire occurrence in the country. The spatial units were 6,066 municipalities of the Spanish peninsular territory and Balearic Islands. The study covered a 13-year series of fire occurrence data. One hundred and eight variables were generated and input to a dedicated Geographic Information System (GIS) to model different factors related to fire ignition. After exploratory analysis, 29 were selected to build a predictive model of human fire ignition using logistic regression analysis. The binary model estimated the probability of high or low occurrence of forest fires, as defined by an ignition danger index that is currently used by the Spanish forest service (number of fires divided by forest area in each municipality). Thirteen explanatory variables were identified by the model. They were related to agricultural landscape fragmentation, agricultural abandonment and development processes. The prediction agreement found between the model binary outputs and the historical fire data was 85.3% for the model building dataset (60% of municipalities). A slightly lower predictive power (76.2%) was found for the validation data (the remaining 40%). The probabilistic output of the logistic was significantly related to the raw ignition index (Spearman correlation of 0.710) used by the Spanish Forest Service. Therefore, the model can be considered a good predictor of human-caused fire risk, aiding spatial decisions related to prevention planning in Spanish municipalities.  相似文献   
176.
During the last decades, high population growth and export-oriented economics in Vietnam have led to a tremendous intensification of rice production, which in turn has significantly increased the amount of pesticides applied in rice cropping systems. Since pesticides are toxic by design, there is a natural concern on the impact of their presence in the environment on human health and environmental quality. The present study was designed to examine the water regime and fate of pesticides (fenitrothion, dimethoate) during two consecutive rice crop seasons in combined paddy rice-fish pond farming systems in northern Vietnam. Major results revealed that 5 and 41% (dimethoate), and 1 and 17% (fenitrothion) of the applied mass of pesticides were lost from the paddy field to the adjacent fish pond during spring and summer crop seasons, respectively. The decrease of pesticide concentration in paddy surface water was very rapid with dissipation half-life values of 0.3 to 0.8 and 0.2 d for dimethoate and fenitrothion, respectively. Key factors controlling the transport of pesticides were water solubility and paddy water management parameters, such as hydraulic residence time and water holding period. Risk assessment indicates that the exposure to toxic levels of pesticides for aquaculture (, ) is significant, at least shortly after pesticide application.  相似文献   
177.
We investigated contamination by endocrine-disrupting chemicals in drinking water from 35 major Italian cities and five popular Italian brands of bottled mineral water. The quality of Italian drinking water was assessed by combing chemical analysis with bioassay to quantify specific estrogenic contaminants and to characterize the actual biological effect of the mixture of chemicals present in drinking water including the contribution of not targeted compounds. The selected contaminants were natural and synthetic steroid estrogens, alkylphenols and bisphenol A, linuron, triazine herbicides, and their metabolites. A specific analytical method was developed based on solid phase extraction of 1 L of water and concentration to 100 μL for quantification by electrospray ionization liquid chromatography tandem mass spectrometry, achieving quantification limits of 0.05–0.36 ng/L for herbicides and 0.64–7.70 ng/L for steroids and phenols. No steroid estrogens were detected in any of the samples, while bisphenol A and nonylphenols were detected in the ranges of 0.82–102.00 and 10.30–84.00 ng/L respectively. Herbicides and their degradation products, when present, were found from slightly above the quantification limits up to 49.91 ng/L, mainly from cities in northern Italy. Chemical analyses were complemented by the performance of a bioassay for the determination of the estrogenic activity in the extracts based on the transactivation of estrogen receptor α-transfected reporter HeLa-ERE-Luciferase-Neomycin cell line. Activity was generally low with maximum estrogenicity of 13.6 pg/L estradiol equivalents.  相似文献   
178.
179.
本研究基于生态文明体制改革的迫切需求,立足我国不同区域现实状况的差异,以我国东部某省为研究对象,基于充分的文献研究、专家咨询和实地调研,以自然资源保护及污染综合防治为核心,深入分析省级层面生态文明管理体制现状,识别当前存在的主要问题,结合国家生态文明体制改革思路和该省实际情况,制订生态文明管理体系及协调机制改革的总体框架,提出重组机构职能配置、优化自然资源管理、理顺污染防治体系、健全有效督政机制、发展绿色化决策等五个针对性的改革建议,为我国省级层面生态文明体制改革提供参考借鉴。  相似文献   
180.
This study investigates the effect of environmental investment and related spillover effects on productivity in the agricultural sector by using a panel data of horticultural firms in Andalusia (Southern Spain). The results indicate a positive relationship between firm investment in environmental practices and productivity improvement, also showing the presence of positive environmental spillovers. In a second-stage of analysis, the incidence of environmental factors in firm specific individual technical efficiency is estimated. This analysis also shows the link between environmental knowledge diffusion and horticultural firms' performance.  相似文献   
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