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521.
为综合评价尾矿库的安全状态,基于尾矿库灾变机理和大量工程实践构建了一套包括3级指标、22个因素的评价指标体系,并确定了评价指标的等级量值区间。采用EAHP和熵权法结合的方式确定指标权重,基于可拓理论评价尾矿库的安全等级。以湖南黄金集团责任有限公司旗下的7座尾矿库为案例,评价其安全状态,根据蒙特卡洛模拟基本理论,基于Crystal Ball对案例进行敏感性分析,找出具体敏感因素,为后期尾矿库安全管理提供简单有效的控制方法。  相似文献   
522.
Abstract: Habitat connectivity is required at large spatial scales to facilitate movement of biota in response to climatic changes and to maintain viable populations of wide‐ranging species. Nevertheless, it may require decades to acquire habitat linkages at such scales, and areas that could provide linkages are often developed before they can be reserved. Reserve scheduling methods usually consider only current threats, but threats change over time as development spreads and reaches presently secure areas. We investigated the importance of considering future threats when implementing projects to maintain habitat connectivity at a regional scale. To do so, we compared forward‐looking scheduling strategies with strategies that consider only current threats. The strategies were applied to a Costa Rican case study, where many reserves face imminent isolation and other reserves will probably become isolated in the more distant future. We evaluated strategies in terms of two landscape‐scale connectivity metrics, a pure connectivity metric and a metric of connected habitat diversity. Those strategies that considered only current threats were unreliable because they often failed to complete planned habitat linkage projects. The most reliable and effective strategies considered the future spread of development and its impact on the likelihood of completing planned habitat linkage projects. Our analyses highlight the critical need to consider future threats when building connected reserve networks over time.  相似文献   
523.
Abstract: Application of island biogeography theory to prediction of species extinctions resulting from habitat loss is based on the assumption that the transformed landscape matrix is completely inhospitable to the taxa considered, despite evidence demonstrating the nontrivial influence of matrix on populations within habitat remnants. The island biogeography paradigm therefore needs refining to account for specific responses of taxa to the area of habitat “islands” and to the quality of the surrounding matrix. We incorporated matrix effects into island theory by partitioning the slope (z value) of species–area relationships into two components: γ, a constant, and σ, a measure of taxon‐specific responses to each component of a heterogeneous matrix. We used our matrix‐calibrated model to predict extinction and endangerment of bird species resulting from land‐use change in 20 biodiversity hotspots and compared these predictions with observed numbers of extinct and threatened bird species. We repeated this analysis with the conventional species–area model and the countryside species–area model, considering alternative z values of 0.35 (island) or 0.22 (continental). We evaluated the relative strength of support for each of the five candidate models with Akaike's information criterion (AIC). The matrix‐calibrated model had the highest AIC weight (wi = 89.21%), which means the weight of evidence in support of this model was the optimal model given the set of candidate models and the data. In addition to being a valuable heuristic tool for assessing extinction risk, our matrix‐calibrated model also allows quantitative assessment of biodiversity benefits (and trade‐offs) of land‐management options in human‐dominated landscapes. Given that processes of secondary regeneration have become more widespread across tropical regions and are predicted to increase, our matrix‐calibrated model will be increasingly appropriate for practical conservation in tropical landscapes.  相似文献   
524.
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   
525.
The courts have provided the traditional battleground for conflicts between environmental interest groups and those whose actions in some way have an adverse impact on the environment The judicial process is a time-consuming one in which all sides usually must concede to some points. Environmental disputes involve complex scientific issues which the court system is not set up to comprehend, so that the process gives the parties to a dispute the sense of having lost control of their own destinies. An increasing number of parties to environmental disputes are turning to negotiation, or mediation, as an alternative in which they can be active parties in the settlement-making process rather than the victims of a court-imposed solution When do the parties to a dispute choose a negotiated settlement over a court battle? To what extent does each party make the concessions necessary to reach an agreement? These questions can be answered by the game theory that provides a model for analyzing the negotiation process. This paper will apply game theory to two environmental conflict cases A series of questions pertinent to the analysis of all environmental disputes will be raised  相似文献   
526.
ABSTRACT: Mathematical models have been widely used in business to minimize cost and maximize profit. In this paper such models are used to help determine the optimum strategy for a beach renourishment project including the initial and subsequent fill quantities and the length of a complete renourishment cycle. The importance of considering economic factors is emphasized, and the sensitivity of the optimal values to changes in the basic parameters of the models are discussed. The possible extensions and limitations of the models are considered.  相似文献   
527.
ABSTRACT. Interest in the geochemistry of groundwater is increasing owing to the great number of current projects involving underground liquid waste storage, artificial recharge of potable water, accidental contamination of groundwater bodies, sanitary landfills, and pollution monitoring. Geochemical techniques used to facilitate the understanding of a groundwater system range from extremely simple to those requiring sophisticated theories, equipment, and procedures. An interpretation of the simple trilinear diagram for samples collected from the Yucatan Peninsula of Mexico provided evidence that the fresh-water body was only a few tens of meters thick and was underlain everywhere by an extensive body of salt water. A geochemical technique that has been used effectively to identify the source of salt water in coastal aquifers is measurement of the carbon-14 concentrations. Carbon-14 has been used in a regional carbonate aquifer to determine the velocity of groundwater movement, rates of chemical reactions, and distribution of hydraulic conductivity. The application of principles of irreversible thermodynamics to groundwater systems provides a basis for constructing models which permit prediction, over both time and space, of changes in head distribution and chemical character of the water resulting from imposed stresses on the system. In essence, proper application of irreversible thermodynamics combines the potential theory of Hubbert with principles of reversible chemical thermodynamics, such as solution of carbonate minerals, to describe and explain controlling chemical reactions and processes of groundwater systems.  相似文献   
528.
人们在重视治理大气和江河湖海等大环境安全问题的时候 ,却忽视了直接危害人身健康甚至生命的室内环境安全问题。在现代社会 ,室内环境安全已经成为影响人们身心健康与安全的重要因素。由于影响室内环境安全的因素复杂 ,科学合理地评价其安全状况对改善室内环境安全具有重要意义。笔者针对建筑室内环境安全系统特征 ,在合理确定评价指标体系的基础上 ,建立了基于灰色关联理论的室内环境安全评价模型 ,并给予了实例验证 ,为室内环境安全评价提供了具有指导意义的技术和方法。  相似文献   
529.
煤层底板突水的突变理论预测方法及其应用   总被引:10,自引:6,他引:10  
基于煤层底板突水的尖点突变特征 ,应用突变理论的方法 ,针对煤层底板突水预测指标监测信号 ,分析了单变量序列尖点突变模型及其稳定判据 ,提出了煤层底板突水的突变理论预测方法。实例表明 ,预测结果与现场工程实际情况相一致 ,证明了该方法可望成为预测煤层底板突水危险性的一条新的有效途径  相似文献   
530.
浅埋型矿井涌水量预测预报的灰色模型   总被引:5,自引:1,他引:5  
矿井涌水量预测 ,对矿井安全及正常生产都至关重要。矿井涌水量预测采用的常规方法对各含水层的水文地质参数依赖性较大 ,而对各因素之间的影响程度难以区分和把握 ,因此 ,在预测预报中的精度较差 ;而采用灰色理论则具有高度的概括性 ,可以把各种不确定因素 ,统统用一个简单的“灰数”来表示 ,并且预测精度高而简单实用。笔者在分析浅埋型矿井涌水量的构成要素的基础上应用灰色系统理论对其涌水量进行了预测 ,其方法与结果对推动矿井水文地质工作有一定的现实意义和指导作用。  相似文献   
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