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501.
利州区农产品基地土壤重金属污染评价   总被引:1,自引:0,他引:1  
肖再亮  兰石  田犀  陈钢  苏培生 《四川环境》2010,29(3):131-135
运用指数法对利州区农产品基地土壤重金属污染进行分析评价,并尝试运用聚类法对重金属进行了聚类分析和污染源推测。从单项污染指数来看,利州区农产品基地8个采样点中所有点元素均不超标。土壤中重金属元素平均单项污染指数由高到低依次为:AsHgCdCuCrPb,其中最高值为As,其值为0.42,可知农产品基地土壤中重金属平均单项污染指数均小于1。从上可以说明该基地的重金属含量受人为影响已在土壤中有所积累,但是总体状况良好。从综合污染指数来看,土壤中重金属平均内梅罗综合污染指数为0.31,其值小于1,属于清洁水平,适合发展有机食品和发展无公害食品生产。聚类分析法得出Pb和Hg的相关系数最大,其值为0.72。说明两者之间具有强正相关性,它们的含量会同时出现增减变化,而Cd和Cu的相关系数为-0.705,说明两者之间是有此消彼长相互抑制的关系。  相似文献   
502.
金沙江流域植被覆盖时空变化特征   总被引:1,自引:0,他引:1  
金沙江流域是长江上游生态脆弱地区,是长江上游水土保持重点防治工程、天然林保护工程和退耕还林工程等生态建设工程的重点实施区。首次利用遥感数据的归一化差值植被指数,采取线性相关分析方法,借助地理信息系统软件,定量化的分析金沙江流域生态建设工程对流域植被的影响。研究结果表明:1999~2008年,金沙江流域年均NDVI在波动中呈显著增加趋势,变化趋势的空间分布存在明显的区域差异,增加速率最快的是农田植被,增加趋势最显著的是灌丛植被;季节平均的NDVI空间分布与年内变化具有明显的空间分异性,不同季节NDVI的变化趋势也存在空间分异性,春、夏、秋和冬季金沙江流域NDVI呈增加趋势的像元分别占总像元的1650%、830%、1170%和1403%;春、夏和秋季都是灌丛NDVI的增加占主导地位,冬季则是草地NDVI的增加占主导地位。基于分析,在“长治”工程、天然林保护工程和退耕还林工程等生态建设工程的综合治理和气候变化的双重影响下,金沙江流域环境向有利的方向发展  相似文献   
503.
应用地累积指数法对珠江(广州河段)表层沉积物中重金属污染程度进行了调查与评价.结果表明,其表层沉积物中重金属的地累积指数大小顺序为:Cu>Cd>Zn>Pb>As>Cr>Hg,其中Cu是主要污染物,Cd、Zn和Pb的地累积指数较高.在所有监测断面中,地累积级别达到4级(强污染)的有5个断面,即4#(雅瑶大桥)、5#(黄歧)、6#(黄沙)、7#(横滘)和16#(花地涌北出口).  相似文献   
504.
For nearly two decades, the Yeast Estrogen Screen (YES) has been used as a valuable tool for determining the total estrogenic potency of various environmental samples, including influent and effluent streams at municipal wastewater plants. However, applying the YES assay to wastewater sludges and stabilized biosolids has been problematic. This is due to co-extracted compounds from the solids either proving toxic to the yeast or masking the presence of estrogenic substances. The present research describes the development and validation of sample preparation steps that mitigate the toxicity effects of municipal wastewater sludge and biosolid samples in the YES assay, while allowing for reliable dose-dependent expression of estrogenic activity. A copper work-up for sulfur removal and chromatographic cleanup with silica and alumina were required in addition to solid-phase extraction to adequately remove interfering compounds. Sample stabilization methods such as autoclaving, lyophilization and formaldehyde treatment were found to be detrimental to the assay. Hence, heat-drying is recommended to prevent cytotoxicity and the degradation of estrogenic substances.  相似文献   
505.
Mayer and Frantz (2004) proposed that their connectedness to nature scale (CNS) provides a measure of people's emotional connection to nature. After reanalyzing data from their article, collecting and analyzing our own data, and conducting a content analysis of CNS scale items, we conclude that the CNS does not measure an emotional connection to nature. Although results from our Study 1 and Study 2 support Mayer and Frantz's conclusion that the CNS measures one predominant factor, we suggest that factor measures cognitive beliefs and not emotional connections. Results from our Studies 3 and 4 suggest that the self-referential, less negatively toned wording of CNS items may account for differences in correlations, between the CNS and environmentalism (a measure of environmental identity) and between the New Ecological Paradigm Scale (a measure of environmental beliefs) and environmentalism, reported by Mayer and Frantz. In Study 5, we suggest that correlation differences reported by Mayer and Frantz may also be attributable to method variance, as opposed to content differences between the CNS and the New Ecological Paradigm scale. We provide recommendations for revising the CNS to focus on beliefs about their connection to nature.  相似文献   
506.
Wind power generation is likely to constitute one of the most extensive human physical exploitation activities of European marine areas in the near future. The many millions of migrating birds that pass these man-made obstacles are protected by international obligations and the subject of public concerns. Yet some bird species are more sensitive to bird–wind turbine mortality than others. This study developed a simple and logical framework for ranking bird species with regard to their relative sensitivity to bird–wind turbine-collisions, and applied it to a data set comprising 38 avian migrant species at the Nysted offshore wind farm in Denmark. Two indicators were selected to characterize the sensitivity of each individual species: 1) relative abundance and 2) demographic sensitivity (elasticity of population growth rate to changes in adult survival). In the case-study from the Nysted offshore wind farm, birds of prey and waterbirds dominated the group of high priority species and only passerines showed a low risk of being impacted by the wind farm. Even where passerines might be present in very high numbers, they often represent insignificant segments of huge reference populations that, from a demographic point of view, are relatively insensitive to wind farm-related adult mortality. It will always be important to focus attention and direct the resources towards the most sensitive species to ensure cost-effective environmental assessments in the future, and in general, this novel index seems capable of identifying the species that are at high risk of being adversely affected by wind farms.  相似文献   
507.
Long-term variability of bioassessments has not been well evaluated. We analyzed a 20-year data set (1984–2003) from four sites in two northern California streams to examine the variability of bioassessment indices (two multivariate RIVPACS-type O/E scores and one multimetric index of biotic integrity, IBI), as well as eight metrics. All sites were sampled in spring; one site was also sampled in summer. Variability among years was high for most metrics (coefficients of variation, CVs ranging from 16% to 246% in spring) but lower for indices (CVs of 22–26% for the IBI and 21–32% for O/E scores in spring), which resulted in inconsistent assessments of biological condition. Variance components analysis showed that the time component explained variability in all metrics and indices, ranging from 5% to 35% of total variance explained. The site component was large (i.e., >40%) for some metrics (e.g., EPT richness), but nearly absent from others (e.g., Diptera richness). Seasonal analysis at one site showed that variability among seasons was small for some metrics or indices (e.g., Coleoptera richness), but large for others (e.g., EPT richness, O/E scores). Climatic variables did not show consistent trends across all metrics, although several were related to the El Ni?o Southern Oscillation Index at some sites. Bioassessments should incorporate temporal variability during index calibration or include climatic variability as predictive variables to improve accuracy and precision. In addition, these approaches may help managers anticipate alterations in reference streams caused by global climate change and high climatic variability.  相似文献   
508.
孙彦君  龙炳清  舒曼  叼剑 《四川环境》2009,28(6):132-135
移植嫁接法是环境工艺创新中的一种重要方法。本文从环境工艺的角度阐述了移植嫁接法的定义,从学科方法和自然过程移植两方面枚举了该法在环境工艺中的应用成果,在此基础上探讨了移植嫁接法中丰富的哲学内涵。  相似文献   
509.
Burg J 《Disasters》2008,32(4):609-630
The concept of vulnerability has become an important part of food security analyses since the 1980s. It is seen as having two sides: exposure to external hazards; and an inability to cope with those shocks, attributed to social, political, and economic factors. Numerous attempts have been made to construct models to determine levels of vulnerability among populations. This paper analyses one such attempt, the Chronic Vulnerability Index (CVI), developed to measure levels of vulnerability to food insecurity in Ethiopia. The example of the CVI reveals many of the difficulties associated with producing a basic model of vulnerability that can be used in disaster mitigation. Ultimately, the CVI assumes that vulnerability is a linear, additive phenomenon with discrete causes and effects and fails to capture interactions between hazards and the human systems that produce and complicate them. The paper concludes with a discussion of alternatives to the CVI.  相似文献   
510.
室内空气质量指数评价模式的研究   总被引:1,自引:0,他引:1  
提出室内空气质量的三级评价标准和五个评价等级,建议依据评价目的,选择相应污染物质作为评价因子。分析常用指数评价模式的特点,建立适用于室内空气质量评价的综合指数模式,该模式是一种客观有效的评价方法。  相似文献   
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