全文获取类型
收费全文 | 785篇 |
免费 | 75篇 |
国内免费 | 190篇 |
专业分类
安全科学 | 67篇 |
废物处理 | 22篇 |
环保管理 | 138篇 |
综合类 | 447篇 |
基础理论 | 152篇 |
污染及防治 | 67篇 |
评价与监测 | 48篇 |
社会与环境 | 62篇 |
灾害及防治 | 47篇 |
出版年
2024年 | 5篇 |
2023年 | 7篇 |
2022年 | 26篇 |
2021年 | 16篇 |
2020年 | 21篇 |
2019年 | 22篇 |
2018年 | 17篇 |
2017年 | 33篇 |
2016年 | 46篇 |
2015年 | 41篇 |
2014年 | 40篇 |
2013年 | 62篇 |
2012年 | 74篇 |
2011年 | 54篇 |
2010年 | 63篇 |
2009年 | 47篇 |
2008年 | 46篇 |
2007年 | 53篇 |
2006年 | 80篇 |
2005年 | 49篇 |
2004年 | 48篇 |
2003年 | 29篇 |
2002年 | 30篇 |
2001年 | 24篇 |
2000年 | 25篇 |
1999年 | 24篇 |
1998年 | 15篇 |
1997年 | 13篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1977年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有1050条查询结果,搜索用时 218 毫秒
261.
262.
基于BP神经网络的垃圾堆放场稳定化程度的综合判别 总被引:2,自引:0,他引:2
分析和判别垃圾堆放场的稳定化程度直接关系到是否需要采取加快稳定化进程,缩短垃圾堆放场的稳定化周期以及是否需要采取措施减少它们对环境的不利影响。本文根据我国垃圾堆放场的具体情况,提出稳定化程度的判别评价指标体系,并且确定稳定化程度的判别标准,运用BP神经网络建立垃圾堆放场稳定化程度的综合判别模型。以三峡库区的一个小型垃圾堆放场为例,采用本文所提出的综合评价模型确定它的稳定化程度,演示模型的运行过程,并为三峡库区的环境保护提供帮助。 相似文献
263.
264.
Integration of Case Studies on Global Change by Means of Qualitative Differential Equations 总被引:2,自引:0,他引:2
We present a novel methodology to integrate qualitative knowledge from different case studies on Global Change related issues
into a single framework. The method is based on the concept of qualitative differential equations (QDEs) which represents
a mathematically well-defined approach to investigate classes of ordinary differential equations (ODEs) used in conventional
modeling exercises. These classes are defined by common qualitative features, e.g., monotonicity, signs, etc. Using the QSIM-algorithm
it is possible to derive the set of possible solutions of all ODEs in the class. By this one can formulate a common, qualitatively
specified cause–effect scheme valid for all case studies. The scheme is validated by testing it against the actually observed
histories in the study regions with respect to their reconstruction by the corresponding QDE. The method is outlined theoretically
and exemplary applied to the problem of land-use changes due to smallholder agriculture in developing countries. It is shown
that the seven case-studies used can be described by a single cause–effect scheme which thus constitutes a pattern of Global Change. As a generally valid prerequisite for sustainability of this kind of land-use the presence of wage labor is shown to represent
a decisive factor.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
265.
M.K.B. Lüdeke O. Moldenhauer G. Petschel-Held 《Environmental Modeling and Assessment》1999,4(4):315-326
Starting from the basic assumption of the syndrome concept that essentially all of the present problematic civilization–nature interactions on the global scale can be subdivided into a limited number of typical patterns, the analysis of the response of these patterns (syndromes) to climate change can make a major contribution to climate impact research, surmounting the difficulties of more common sectoral ceteris paribus impact studies with respect to their systemic integration. In this paper we investigate in particular the influence of climate on the regional proneness or disposition towards one of the most important syndromes with respect to famines and malnutrition, the Sahel Syndrome. It describes the closely interlinked natural and socioeconomic aspects of rural poverty driven degradation of soil and vegetation on marginal sites. Two strategies of global climate impact assessment on a spatial 0.5°×0.5° grid were pursued: (a) As a measure for the climate sensitivity of the regional proneness, the absolute value of the gradient of the disposition with respect to the global field of 3} 12 monthy normals of temperature, irradiation and precipitation is calculated. (b) The disposition was evaluated for two different climate forecasts under doubled atmospheric CO2 concentration. For both strategies two new quantitative global models were incorporated in a fuzzy-logic-based algorithm for determining the disposition towards the Sahel Syndrome: a neural-net-based model for plant productivity and a waterbalance model which calculates surface runoff considering vertical and lateral fluxes, both driven by the set of 36 monthly climatological normals and designed to allow very fast global numerical evaluation.Calculation (b) shows that the change in disposition towards the Sahel Syndrome crucially depends on the chosen climate forecast, indicating that the disagreement of climate forecasts is propagated to the impact assessment of the investigated socio-economic pattern. On the other hand the regions with a significant increase in disposition in at least one of the climate scenario-based model runs form a subset of the regions which are indicated by the local climate sensitivity study (a) as highly sensitive – illustrating that the gradient measure applied here provides a resonable way to calculate an upper limit or worst case of negative climate impact. This method is particularly valuable in the case of uncertain climate predictions as, e.g., for the change in precipitation patterns. 相似文献
266.
Sergey Venevsky 《Mitigation and Adaptation Strategies for Global Change》2006,11(1):241-268
The conceptual scheme of integrated assessment of vulnerability to climate change in Siberian forests is elaborated and applied
to the extensive area in Siberia covered by Larch forests. Forest stakeholders on the provincial level are identified to be
the most relevant for an integrated impact assessment. Organisation of the assessment study as a combination of
'top-down' and 'bottom-up' approaches is suggested. Major biophysical vulnerability indexes and regional syndromes are identified
as the growing stock and current increment averaged by administrative unit. Models and data suitability and quality for an
analysis of biophysical vulnerability in conditions of climate change are studied for Siberian forests and future development
trends are identified. An application of the elaborated conceptual scheme, which employs two models of different type and
forest inventory data, is presented for the Larch area. 相似文献
267.
四论灾害系统研究的理论与实践 总被引:50,自引:13,他引:50
作者曾分别于1991,1995和2001年发表了关于灾害研究理论与实践的3篇文章,对灾害系统的性质、动力学机制等进行了探讨.本文在前3篇文章的基础上,从综合灾害风险管理的角度,完善了灾害系统的结构与功能体系,论证了灾情形成过程中恢复力的作用机制,分析了区域开发与安全建设的互馈关系,构建了区域综合减灾的行政管理体系,提出了由政府、企业与社区构成的区域综合减灾范式.研究结果表明,区域灾情形成过程中,脆弱性与恢复力有着明显的区别,脆弱性是区域灾害系统中致灾因子、承灾体和孕灾环境综合作用过程的状态量,它主要取决于区域的经济发达程度与社区安全建设水平;恢复力则是灾害发生后,区域恢复、重建及安全建设与区域发展相互作用的动态量,它主要取决于区域综合灾害风险行政管理能力、政府与企业投入和社会援助水平.区域安全水平与土地利用的时空格局和产业结构关系密切,通过划定区域高风险“红线区“的办法,调整土地利用时空格局和产业结构,有利于建立区域可持续发展的综合减灾范式.针对区域自然灾害系统存在着相互作用、互为因果的灾害链规律,以及灾害系统所具有的结构与功能特征,完善由纵向、横向和政策协调共同组成的一个“三维矩阵式“的区域综合减灾行政管理体系,构建以政府为主导、企业为主体、社区全面参与的区域综合减灾范式.以此促进在发展中提高区域减灾能力,并在一定安全水平下,建设区域可持续发展模式. 相似文献
268.
Mark Meo Will Focht Lowell Caneday Robert Lynch Fekadu Moreda Blake Pettus Ed Sankowski Zev Trachtenberg Baxter Vieux Keith Willett 《Journal of the American Water Resources Association》2002,38(2):541-554
ABSTRACT: Current research in the Illinois River Basin is designed to develop and test a policy formulation protocol that will foster watershed management policy that is fully legitimated (i.e., policy that is technically effective, economically efficient, administratively implementable, politically feasible, and socially acceptable). This paper describes the results of the initial baseline impact assessment that includes physical, biological, economic, legal, and social systems as well as the development of a watershed management decision support system that is used to integrate technical information and analyses, and to facilitate policy maker and stakeholder negotiation workshops. Numerically modeled and visually simulated environmental impacts serve as the basis for developing alternative policy maker scenarios for prospective watershed management policies. These scenarios, which will be subjected to stakeholder review and negotiation, will undergo iterative review and amendment by policy makers and stakeholder groups to produce a recommended watershed management policy that satisfies all five substantive legitimation criteria. Preliminary results from the baseline social impact assessment indicate that fully legitimated policy is indeed obtainable. 相似文献
269.
270.