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51.
ABSTRACT: In a study to measure the efficacy of chioramines at inactivating Giardia cysts, the ability of cysts to excyst was measured after exposure to different concentrations of chloramines, for different times, and at different temperatures and pH. The chloramines were generated by mixing ammonium sulfate and sodium hypochlorate in water to approximate a 7:1 chlorine:ammonia ratio by weight. Times of 40, 80, 180, and 270 minutes; temperatures of 3, 10, and 18°C; target chioramine concentrations of 0.4, 1.4, 2.0, and 2.6 mg/L; and pH of 7.0 and 8.5 were the actual values tested. The combinations of these variables that were able to inactivate >99.8 percent of the cysts were a minimum chloramine concentration of 2.26 mg/L applied for 270 minutes at a water temperature of 10°C; and at 18°C, averaged minimum chloramine concentrations of 2.14 and 1.55 mg/L applied for 180 and 270 minutes, respectively. The minimum CT values corresponding to these combinations capable of >99.8 percent cyst inactivation, are 610 at 10°C and 385 at 18°C. Temperature was noted to exert a major effect on the ability of chloramines to inactivate cysts. Modifications of the methods used to generate chloramines may have an effect on the capacity of this disinfectant to inactivate cysts.  相似文献   
52.
MFAM模型在河流水质污染模拟及预测中的应用   总被引:2,自引:0,他引:2  
张学成 《四川环境》1994,13(4):10-15
文中以时间序列分析为基础,介绍了均值生成函数这一崭新概念,并且经成份因子提取分析推导建立了模拟序列的数字模型(简记为MFAM),经对黄河下游花园口断面的1988-1989年实测水质污染指标溶解氧(DO),氨氧,化学耗氧量(COD),五日生化需氧量(BOD5)等序列模拟,结果表明MFAM模型能较好地模拟河流水质污染指标的变化趋势,拟合平均误差只有5.2-6.4%,MFAM模型应用于预测1990-1991年水质污染指标变化,结果表明预测精度达85%以上,文中最后得出结论:MFAM模型应用于河流污染模拟和预测,是完全可行且十分方便。  相似文献   
53.
ABSTRACT: By integrating literature from flood hazard research and urban economics a theoretical structure is developed to explain changes in residential land values following flood events. The negative aspects of the flood hazard are shown to be capitalized in the value of the property. It is further suggested that land values (i.e., capitalization) will vary both spatially across the floodplain and temporally depending on the frequency, severity and spatial characteristics of the flood event. Previous work in this area has not addressed the capitalization process explicitly and has not specifically examined the ability of the land market to recover. This may account for the contradictory findings in the published literature.  相似文献   
54.
A method for evaluating areas for national park status   总被引:1,自引:0,他引:1  
A procedure for evaluating different areas as national parks based on a scoring system is proposed. A National Park Evaluation Form (NPEF) evaluating natural, cultural, and recreational resources in accordance with international criteria for national parks is presented. The evaluation points given to an area indicate the possibility of the area becoming a national park. In this method, subjectivity and bias have been minimized by a special application of the Delphi technique. The method outlined here could help in the efforts of selecting and establishing national parks in many countries.  相似文献   
55.
Methods for life cycle assessment of products (LCA) are most often based on the general prevention principle, as opposed to the risk minimization principle. Here, the desirability and feasibility of a combined approach are discussed, along with the conditions for elaboration in the framework of LCA methodology, and the consequences for LCA practice. A combined approach provides a separate assessment of above and below threshold pollution, offering the possibility to combat above threshold impacts with priority. Spatial differentiation in fate, exposure, and effect modelling is identified to play a central role in the implementation. The collection of region-specific data turns out to be the most elaborate requirement for the implementation in both methodology and practice. A methodological framework for the construction of characterization factors is provided. Along with spatial differentiation of existing parameters, two newly introduced spatial parameters play a key role: the sensitivity factor and the threshold factor. The practicability of the proposed procedure is illustrated by an example of its application. Providing a reasonable data availability, the development of separate LCA characterization factors for the respective assessment of pollution levels above and below environmental threshold values seems to be a feasible task that may add to LCA credibility.  相似文献   
56.
Lake Erie water quality has improved dramatically since the degraded conditions of the 1960s. Additional gains could be made, but at the expense of further investment and reductions in fishery productivity. In facing such cross-jurisdictional issues, natural resource managers in Canada and the United States must grapple with conflicting objectives and important uncertainties, while considering the priorities of the public that live in the basin. The techniques and tools of decision analysis have been used successfully to deal with such decision problems in a range of environmental settings, but infrequently in the Great Lakes. The objective of this paper is to illustrate how such techniques might be brought to bear on an important, real decision currently facing Lake Erie resource managers and stakeholders: the choice of new phosphorus loading targets for the lake. The heart of our approach is a systematic elicitation of stakeholder preferences and an investigation of the degree to which different phosphorus-loading policies might satisfy ecosystem objectives. Results show that there are potential benefits to changing the historical policy of reducing phosphorus loads in Lake Erie.  相似文献   
57.
An Exploration of the Value of Naturalness and Wild Nature   总被引:2,自引:0,他引:2  
The source of the value of naturalness is of considerable relevance for the conservation movement, to philosophers, and to society generally. However, naturalness is a complex quality and resists straightforward definition. Here, two interpretations of what is “natural” are explored. One of these assesses the naturalness of species and ecosystems with reference to a benchmark date, such as the advent of industrialization. The value of naturalness in this case largely reflects prioritization of the value of biodiversity. However, the foundation of our understanding of naturalness is that it describes processes that are free of human intervention. Conflict between the two interpretations of naturalness is apparent in the claim that naturalness can be enhanced by human intervention, in the form of ecological restoration. Although naturalness in its purest form precludes human intervention, some human activities are also apparently more natural than others. This continuum of naturalness relates to the autonomy of the individual from abstract instrumentalism, which describes a particular form of influence ubiquitous in contemporary society. The value of naturalness reflects both dissatisfaction with these threats to personal autonomy, and respect for wild nature as the embodiment of a larger-than-human realm.  相似文献   
58.
基于2015~2018年苏州张家港站CO2在线观测数据,采用时序检查、选取稳定性数据、异常值剔除等质量控制方法获得可靠数据,并通过平均移动过滤(MAF)本底筛分法获得本底数据,讨论苏南地区CO2变化特征.结果发现:CO2本底浓度日变化为单峰结构,谷值和峰值分别出现在下午15:00和凌晨5:00前后;季节变化为双峰结构,峰值分别出现在12月和4月;日、季节变化的分布特征均与陆地生态系统、气象条件和人类活动有关.此外,2015~2018年CO2浓度呈逐年上升趋势,抬升浓度占比逐年增加,吸收浓度占比波动较小,表明人类活动对CO2浓度的影响正在逐年增加;而陆地生态系统对CO2吸收汇的作用则相对稳定.源汇分析显示,CO2抬升浓度随季节小幅波动;吸收浓度则夏半年较低,冬半年较高;抬升浓度日变化为单峰结构,谷值和峰值分别出现在15:00和8:00前后,早晨正值上班高峰,机动车排放可能为早晨峰值的主要因素;吸收浓度日间低、夜间高,这主要与植物光合作用及对流输送有关.分析CO2浓度与风的关系发现,所有季节静风情况下,CO2浓度偏高均最为明显,大部分方向CO2浓度高低与风速大小有明显的负相关,其中S~WNW方向偏高最为明显,这可能是因为SW~NW方向主要为内陆城市群,且测站周边建筑区主要位于W~N方向,弱风有利于本地排放累积的结果.此外,WNW方向风速较大时浓度仍偏高明显,可能与测站W~N方向为建筑区及内陆城市群有关;而测站偏东方向主要为农田和林区,受人类活动影响较小,且海上气流较为洁净,故偏东风较弱时浓度也不高;说明了CO2浓度除了与风速大小有关外,与周边下垫面类型及较远距离环境特征(城市群或海洋)也有一定的关系.  相似文献   
59.
Abstract: Despite advances in the quality of participatory decision making for conservation, many current efforts still suffer from an inability to bridge the gap between science and policy. Judgment and decision‐making research suggests this gap may result from a person's reliance on affect‐based shortcuts in complex decision contexts. I examined the results from 3 experiments that demonstrate how affect (i.e., the instantaneous reaction one has to a stimulus) influences individual judgments in these contexts and identified techniques from the decision‐aiding literature that help encourage a balance between affect‐based emotion and cognition in complex decision processes. In the first study, subjects displayed a lack of focus on their stated conservation objectives and made decisions that reflected their initial affective impressions. Value‐focused approaches may help individuals incorporate all the decision‐relevant objectives by making the technical and value‐based objectives more salient. In the second study, subjects displayed a lack of focus on statistical risk and again made affect‐based decisions. Trade‐off techniques may help individuals incorporate relevant technical data, even when it conflicts with their initial affective impressions or other value‐based objectives. In the third study, subjects displayed a lack of trust in decision‐making authorities when the decision involved a negatively affect‐rich outcome (i.e., a loss). Identifying shared salient values and increasing procedural fairness may help build social trust in both decision‐making authorities and the decision process.  相似文献   
60.
Coastal flooding affects physical and social place attachments. Values-based approaches to climate change adaptation examine how risks to place attachments are distributed within and among communities, with a view to informing equitable adaptation policies. In this nascent body of research, divergent theoretical frameworks and empirical approaches to measuring social values are evolving. While some studies explore the things people value about their everyday lives generally—the lived values approach, others locate specific social and cultural values in geographic space—the landscape values mapping approach. This study aims to compare the explanatory value of these two approaches for understanding the social risks of sea-level rise, and appraise whether either or both approaches are likely to meet local adaptation planning needs. It does this by examining the potential social impacts of sea-level rise in Kingston Beach, Australia, informed by a mail-out survey of the community. The lived values approach identified that the natural environment, scenery, relaxed lifestyle and safety are highly important to local residents, while the landscape values mapping approach revealed that Kingston Main Beach is the most highly valued of eight coastal landscape units. Incorporating the landscape values mapping into the lived values cluster analysis revealed that while Kingston Main Beach is highly important for its recreational value to some members of the community, for others manmade features such as community halls or sports ovals may be of higher importance because they facilitate social interactions. There is potential to further integrate these two approaches to better inform adaptation policy about how lived and landscape values are distributed among communities, where they are located in space and whether they change over time. A deeper understanding of such assigned values can lead to improved engagement with coastal residents to inform adaptation policy now and into the future.  相似文献   
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