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921.
ABSTRACT: Among the many concerns associated with global climate change, the potential effects on water resources are frequently cited as the most worrisome. In contrast, those who manage water resources do not rate climatic change among their top planning and operational concerns. The difference in these views can be associated with how water managers operate their systems and the types of stresses, and the operative time horizons, that affect the Nation's water resources infrastructure. Climate, or more precisely weather, is an important variable in the management of water resources at daily to monthly time scales because water resources systems generally are operated on a daily basis. At decadal to centennial time scales, though, climate is much less important because (1) forecasts, particularly of regional precipitation, are extremely uncertain over such time periods, and (2) the magnitude of effects due to changes in climate on water resources is small relative to changes in other variables such as population, technology, economics, and environmental regulation. Thus, water management agencies find it difficult to justify changing design features or operating rules on the basis of simulated climatic change at the present time, especially given that reservoir-design criteria incorporate considerable buffering capacity for extreme meteorological and hydro-logical events.  相似文献   
922.
Abstract: The unit of trade in ecosystem services is usually the use of a proportion of the parcels of land associated with a given service. Valuing small changes in the provision of an ecosystem service presents obstacles, particularly when the service provides non‐use benefits, as is the case with conservation of most plants and animals. Quantifying non‐use values requires stated‐preference valuations. Stated‐preference valuations can provide estimates of the public's willingness to pay for a broad conservation goal. Nevertheless, stated‐preference valuations can be expensive and do not produce consistent measures for varying levels of provision of a service. Additionally, the unit of trade, land use, is not always linearly related to the level of ecosystem services the land might provide. To overcome these obstacles, we developed a method to estimate the value of a marginal change in the provision of a non‐use ecosystem service—in this case conservation of plants or animals associated with a given land‐cover type. Our method serves as a tool for calculating transferable valuations of small changes in the provision of ecosystem services relative to the existing provision. Valuation is achieved through stated‐preference investigations, calculation of a unit value for a parcel of land, and the weighting of this parcel by its ability to provide the desired ecosystem service and its effect on the ability of the surrounding land parcels to provide the desired service. We used the water vole (Arvicola terrestris) as a case study to illustrate the method. The average present value of a meter of water vole habitat was estimated at UK£12, but the marginal value of a meter (based on our methods) could range between £0 and £40 or more.  相似文献   
923.
The perspectives and knowledge of decision makers, especially those at the provincial level, have great impact on the progress of climate change adaptation in China. Therefore, identifying knowledge gaps and enhancing climate adaptation awareness of decision makers at that level is very important. Based on this aim, we conducted a survey of climate change adaptation awareness among 85 administrative and management personnel from governmental departments responsible for climate change adaptation planning in five provinces. Study findings revealed that over half of respondents have knowledge of climate change adaptation measures, but the extent of understanding varied across different adaptation aspects and regions. Among the different aspects, understanding of measures related to human health protection was the lowest. A large majority of respondents indicated an eagerness to obtain knowledge and information about climate change adaptation, but the main barrier is a lack of training and learning material. When making adaptation plans or policies, the greatest obstacle expressed was a funding shortage. Information generated from this study can provide direction and guidance for training and educating provincial decision makers in order to improve the levels of adaptation planning and policy making.  相似文献   
924.
This article describes and tests a systems theory-based policy indicators model. The framework is used to examine propositions about linkages between states' ecological-spatial characteristics and subsequent selected solid waste management (SWM) -related environmental policies. It was hypothesized that state characteristics of: (1) population density (used as a garbage-per-land area index), (2) population convergence within urban areas, and (3) percent population change in the interval 1980–1985, could jointly explain state variation in both the number and the vigor of SWM policy outputs. Greater levels of spatial pressure were proposed to be related directly to more numerous, more convincing policies. Proposals are grounded in the literature of organizational search theory, crisis stimulation, and technological pressure. Results revealed that the sociospatial model in fact could explain a reasonable proportion of policy variation across states. However, not all hypotheses are supported. Population change shows an indirect, rather than the anticipated direct, relationship with policy output levels. In addition, when used in the model as a pollution intensity index, population density failed to contribute significantly to an explanation of differences in state SWM policy levels. The analysis raises questions about changes occurring over time in the nature and direction of linkages between sociospatial measures and policy responses. This study suggests that strengthening policy indicator models may require questioning key assumptions and theoretical bases, conducting longitudinal studies, and factoring in political, economic, and other policy environment forces.  相似文献   
925.
Cumulative environmental change or cumulative effects may result from the additive effect of individual actions of the same nature or the interactive effect of multiple actions of a different nature. This article reviews conceptual frameworks of cumulative environmental change and describes analytical and institutional approaches to cumulative effects assessment (CEA). A causal model is a common theoretical construct, although the frameworks vary in their emphasis on different components of the model. Two broad approaches to CEA are distinguished: one scientific and the other planning oriented. These approaches should not be interpreted as competing paradigms but rather different interpretations of the scope of CEA. Each approach can provide a distinct but complementary contribution to the analysis, assessment, and management of cumulative effects. A comparison of the institutional and legislative response to CEA in Canada and the United States shows that Canada is following the American example of incorporating the analysis and assessment of cumulative effects into regulatory actions and administrative procedures that also govern environmental impact assessment.  相似文献   
926.
尽管人类对温室效应和全球变化的认识还是很不充分的,但是继续拖延不采取措施是危险的,采取对抗温室效应和全球变化的措施是行不通的。只有在继续进行全球性科学研究的同时,积极寻求适应一定程度全球变化的措施,并立即着手减少温室气体的排放才是唯一明智的态度。化石能源是人类社会生存和发展的基础,既使用化石能源,又不排放二氧化碳是不可能是。首要的任务是减少化石能源的使用。  相似文献   
927.
农业病虫害的灾变预测及预报精度分析   总被引:1,自引:0,他引:1  
赵惠燕  汪世泽 《灾害学》1993,8(4):10-14
在农业病虫害突变规律的研究基础上,建立了定性与定量的尖角突变模型,确定了各病虫的突变区域。根据综合控制变量所确定的边界值,对未来病虫发生发展趋势进行预测。经多年历史资料检验和1992年农业病虫害发生突变的趋势预报证明:准确率高,覆盖面广。  相似文献   
928.
ABSTRACT: The Conservation Areas in South Florida have been considered as one of the major water storage areas to provide a water supply for the Everglades National Park and Lower East Coast (LEC). Due to the increasing water demands of the area, additional backpumping of the surplus runoff from the LEC area into the Conservation Areas has been considered as one of several alternative plans. The Receiving Water Quantity (EPA, 1971) model has been adapted and modified to be applicable in the Conservation Areas to investigate the possible impact of additional inflow under various backpumping cases. The modification of the model included Manning's roughness coefficient, depth of flow, width of hypothetical channels through marsh areas, rainfall input, seepage rate, etc. The use of the Monte Carlo technique for area computations was found to be easy and time saving both in area and weighting rainfall input to each node. Comparison of results generated by this modified model with the recorded values in Conservation Areas 1 and 2A indicated that the model not only can be a very good evaluation tool to simulate the hydraulic regime of the Conservation Areas system but also a proper tool for investigating the impact of additional inflow resulting from the backpumping related to the water use planning and management.  相似文献   
929.
ABSTRACT Attitudes toward the development of the American West have undergone important changes over the past century just as the nature of water resources as factors in development have changed. Viewing these changes processually, stages for water resources definition and use can be identified in the total process of western cultural development. The first stage involves the value of water resource development as a stimulus to population and economic growth in the West. The second stage, still in process', adopts a dominant cultural norm which sees water resource development as inevitable if not necessary to keep up with growth. A third stage to this evolutionary process is incipient. Future cultural values and thinking with respect to water resource development will be to look at development as a means for controlling or managing both the location and quantity of population and economic growth. To this end planners will have to become concerned with the questions of human adaptation. Concern will have to be given to the problems of getting a living which enables individuals to meet the subsistence needs of self and family, to establishing community which provides for cooperation among individuals and the management of conflict, to establishing improved communication which promotes interpersonal interaction, and for fostering innovation which provides the new ideas necessary to adapt to new environmental situations.,  相似文献   
930.
In this paper, we analyze the institutional work that underlies the attempt to institutionalize a more active role of citizens in urban planning. We draw on a case in which a group of citizens aims to redevelop a brownfield site into a vital urban area. This citizens’ initiative is co-creating a new form of urban planning with the municipality, private organizations and individual citizens. The study shows how citizens’ initiatives can be a driver for institutional change, but that uncertainties about new institutions tend to reinforce the maintenance of existing ones. This paradox explains why even if the ambition for a new form of planning is widely shared, actually realizing institutional change can still be difficult and time-consuming.  相似文献   
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