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471.
简要统计了2015年3-4月国内发生的各种环境事件112起,包括沙尘天气17起,污染事件21起,地震42起,山体滑坡和泥石流7起,旱灾4起以及其他自然灾害21起. 相似文献
472.
简要统计了2015年9-10月国内发生的各种环境事件96起,包括污染事件13起,地震41起,山体滑坡和泥石流15起,旱灾5起以及其他自然灾害22起. 相似文献
473.
Abstract: Active adaptive management looks at the benefit of using strategies that may be suboptimal in the near term but may provide additional information that will facilitate better management in the future. In many adaptive‐management problems that have been studied, the optimal active and passive policies (accounting for learning when designing policies and designing policy on the basis of current best information, respectively) are very similar. This seems paradoxical; when faced with uncertainty about the best course of action, managers should spend very little effort on actively designing programs to learn about the system they are managing. We considered two possible reasons why active and passive adaptive solutions are often similar. First, the benefits of learning are often confined to the particular case study in the modeled scenario, whereas in reality information gained from local studies is often applied more broadly. Second, management objectives that incorporate the variance of an estimate may place greater emphasis on learning than more commonly used objectives that aim to maximize an expected value. We explored these issues in a case study of Merri Creek, Melbourne, Australia, in which the aim was to choose between two options for revegetation. We explicitly incorporated monitoring costs in the model. The value of the terminal rewards and the choice of objective both influenced the difference between active and passive adaptive solutions. Explicitly considering the cost of monitoring provided a different perspective on how the terminal reward and management objective affected learning. The states for which it was optimal to monitor did not always coincide with the states in which active and passive adaptive management differed. Our results emphasize that spending resources on monitoring is only optimal when the expected benefits of the options being considered are similar and when the pay‐off for learning about their benefits is large. 相似文献
474.
农村生活污染开展环境统计的思考 总被引:3,自引:1,他引:2
污染源排放数据是各项环境管理的关键基础和重要依据,目前,环保部门对除农村生活污染以外的其他污染源排放数据已基本摸清。在"三农"发展的同时,农村环境保护已被提上国家日程,日前国务院下发了《关于加强环境保护重点工作的意见》,要求开展农村环境统计,环境统计主管部门也在考虑"十二五"期间将农村生活污染纳入环境统计的可能性。鉴于农村生活污染的特点,开展环境统计尚存在较多难点。因此,分析农村生活污染的特点,思考将其纳入环境统计的可行性和操作性,对健全环境统计体系、改善农村环境质量、全方位掌控和监管各类污染源排放,具有高度的前瞻性和重要性。 相似文献
475.
Eugene Z. Stakhiv 《Journal of the American Water Resources Association》2011,47(6):1183-1196
Stakhiv, Eugene Z., 2011. Pragmatic Approaches for Water Management Under Climate Change Uncertainty. Journal of the American Water Resources Association (JAWRA) 47(6):1183–1196. DOI: 10.1111/j.1752‐1688.2011.00589.x Abstract: Water resources management is in a difficult transition phase, trying to accommodate large uncertainties associated with climate change while struggling to implement a difficult set of principles and institutional changes associated with integrated water resources management. Water management is the principal medium through which projected impacts of global warming will be felt and ameliorated. Many standard hydrological practices, based on assumptions of a stationary climate, can be extended to accommodate numerous aspects of climate uncertainty. Classical engineering risk and reliability strategies developed by the water management profession to cope with contemporary climate uncertainties can also be effectively employed during this transition period, while a new family of hydrological tools and better climate change models are developed. An expansion of the concept of “robust decision making,” coupled with existing analytical tools and techniques, is the basis for a new approach advocated for planning and designing water resources infrastructure under climate uncertainty. Ultimately, it is not the tools and methods that need to be revamped as much as the suite of decision rules and evaluation principles used for project justification. They need to be aligned to be more compatible with the implications of a highly uncertain future climate trajectory, so that the hydrologic effects of that uncertainty are correctly reflected in the design of water infrastructure. 相似文献
476.
Measurements of low-level radioactivity often give results of the order of the detection limit. For many applications, interest is not only in estimating activity concentrations of a single radioactive isotope, but focuses on multi-isotope analyses, which often enable inference on the source of the activity detected (e.g. from activity ratios). Obviously, such conclusions become questionable if the measurement merely gives a detection limit for a specific isotope. This is particularly relevant if the presence of an isotope, which shows a low signal only (e.g. due to a short half-life or a small transition probability), is crucial for gaining the information of interest. 相似文献
477.
478.
本次吊扇电机温升水平测试活动采用平行样品试验方案,尽管通过了严格的样品定制、测试和筛选以控制样品离散性,但所收集到的水平测试数据经过稳健统计法和Z值评估法的分析后发现平行样品的离散性对水平测试结果的影响不可忽略,导致所给出的评价结果是具有较大的风险性和不公平性。这意味着该次水平测试活动采用平行样品试验方案一种错误的选择。 相似文献
479.
ESTABLISHING STATISTICAL DESIGN CRITERIA FOR WATER QUALITY MONITORING SYSTEMS: REVIEW AND SYNTHESIS1
Robert C. Ward Jim C. Loftis 《Journal of the American Water Resources Association》1986,22(5):759-767
ABSTRACT: Regulatory water quality management has placed fairly extensive information expectations on routine, fixed-station monitoring without a corresponding emphasis being placed on the need to design monitoring systems to meet these expectations. To correct the situation there is increasing interest in developing more quantitative monitoring system design procedures which incorporate the statistical nature of sampling. In examining the development of such quantitative criteria, this paper describes the roles of statistics in a systematic approach to monitoring - initial design and routine reporting of results - and reviews the use of statistics in each. The paper emphasizes the need to tie the two together, via statistical design criteria, in order for the identified information expectations to be met in a statistically sound manner. However, the use of statistics in water quality monitoring is noted as currently being as much an art as it is a science. 相似文献
480.
Vijay P. Singh Kulwant Singh 《Journal of the American Water Resources Association》1987,23(6):1185-1189
ABSTRACT: The principle of maximum entropy (POME) was used to derive an alternative method for parameter estimation for the three parameter lognormal (TPLN) distribution. Six sets of annual peak discharge data were used to evaluate this method and compare it with the methods of moments and maximum likelihood estimation. 相似文献