全文获取类型
收费全文 | 468篇 |
免费 | 42篇 |
国内免费 | 96篇 |
专业分类
安全科学 | 36篇 |
废物处理 | 1篇 |
环保管理 | 141篇 |
综合类 | 204篇 |
基础理论 | 90篇 |
环境理论 | 1篇 |
污染及防治 | 50篇 |
评价与监测 | 15篇 |
社会与环境 | 57篇 |
灾害及防治 | 11篇 |
出版年
2023年 | 13篇 |
2022年 | 9篇 |
2021年 | 17篇 |
2020年 | 16篇 |
2019年 | 16篇 |
2018年 | 12篇 |
2017年 | 19篇 |
2016年 | 27篇 |
2015年 | 23篇 |
2014年 | 31篇 |
2013年 | 41篇 |
2012年 | 35篇 |
2011年 | 35篇 |
2010年 | 25篇 |
2009年 | 27篇 |
2008年 | 23篇 |
2007年 | 49篇 |
2006年 | 24篇 |
2005年 | 18篇 |
2004年 | 15篇 |
2003年 | 6篇 |
2002年 | 10篇 |
2001年 | 11篇 |
2000年 | 10篇 |
1999年 | 10篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 11篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1969年 | 1篇 |
排序方式: 共有606条查询结果,搜索用时 15 毫秒
121.
122.
ROBYN S. WILSON 《Conservation biology》2008,22(6):1452-1460
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
123.
不同轮作模式下作物根际土壤养分及真菌群落组成特征 总被引:2,自引:8,他引:2
为研究宁夏中部干旱带不同轮作模式下土壤养分及真菌群落组成的特征,以谷子轮作大豆(MRG)、轮作籽粒苋(MRA)、轮作藜麦(MRQ)及谷子连作(CK)为对象,测定了土壤养分含量,并利用Illumina MiSeq高通量测序平台测定了土壤真菌的ITS变异区序列.结果表明,不同轮作模式对土壤养分的影响存在差异.3种轮作模式下土壤pH和电导率均有所下降,土壤全氮、全钾、全磷和有机质含量均上升,OTUs数和α多样性指数均高于连作.真菌群落组成研究结果显示,子囊菌门(Ascomycota)为4种模式下的优势菌群.聚类分析显示MRA和MRG的真菌属组成最为相似,其次是MRQ, CK与3种轮作模式相差较大.相关性分析显示,土壤养分与几种优势真菌属呈显著相关性(P<0.05或P<0.01),土壤全氮、全钾、硝态氮和有机质含量是影响土壤真菌群落最主要的因子.主成分分析(PCA)表明,MRG轮作模式优于MRA和MRQ模式.综上所述,轮作提高了真菌群落多样性指数,改变了土壤真菌群落结构,改善了土壤肥力状况,其中以谷子与大豆轮作效果最佳,建议将谷豆轮作作为中部干旱带杂粮产业中主要的轮作模式之一进行推... 相似文献
124.
Extreme value analysis of Munich air pollution data 总被引:1,自引:0,他引:1
We present three different approaches to modelling extreme values of daily air pollution data. We fitted a generalized extreme
value distribution to the monthly maxima of daily concentration measures. For the exceedances of a high threshold depending
on the data, the parameters of the generalized Pareto distribution were estimated. Accounting for autocorrelation, clusters
of exceedances were used. To obtain information about the relationship of the exceedance of the air quality standard and possible
predictors we applied logistic regression. Results and their interpretation are given for daily average concentrations of
ozone and nitrogen dioxide at two monitoring sites within the city of Munich. 相似文献
125.
This study analyzed a time series data of daily subPSI values to determine the temporal and spatial characteristics of ambient air-quality in Taiwan by employing the Varimax rotational method. The first and second rotational principal components nearly accounted for 54 and 19% for the variation of subPSI values over Taiwan. The factor loadings between rotational principal components and subPSI values of air pollutants identified the first and second components as combustion and photochemical sources, respectively. Time series analysis of rotational component scores associated with regions showed the relationships between rotational components and subPSI values and also revealed the optimum simulation period for combustion and photochemical sources. 相似文献
126.
Jackie Sellers Ronald M. North 《Journal of the American Water Resources Association》1979,15(1):167-181
ABSTRACT: The “principles and standards for planning water and related land resources” were made effective October 25, 1973. The document was noticeably deficient in suggestions for the necessary implementing procedures to ensure its success. Current implementing procedures are based on an incorrect premise of maximizing a single objective subject to non-quantified constraints. A successful implementation of multiple objective planning requires optimizing simultaneously several competitive goals. A system of goal programming has been developed and applied to decisionmaking situations as a test of its usefulness in planning for multiple objective water resources projects. The result is a project planning process which can be replicated for adjustments in expected resource supplies or demands to provide a tradeoff matrix between economic and environmental objectives as well as traditional functional purposes. This procedure, tested on the Cross Florida Barge Canal, is an integrated analysis of economic and environmental values which may be as effective in implementing multiple objective planning as the “Green Book” was in developing the now inappropriate benefit cost analysis. 相似文献
127.
当前,我国环境的根本问题是由粗放式的经济发展模式所引起的,而这一发展模式的根源在于"中国式央地分权"下的政府行为。这种具有中国特色的分权模式的独特之处在于中央政府对地方经济放权的同时,仍然保持政治上的集权控制,上级政府根据绩效考核提拔地方官员,即"经济分权、政治集权"特性。中国式分权下,我国的环境治理体制依据行政区域的划分来设置管理权限,按照政府层级的构成进行垂直式领导,即中央政府统一制定环境政策,地方政府负责各辖区内环境政策的执行。在全国范围内,央地两级政府的关系表现为动态的重复博弈。针对我国现行环境规制执行策略,借助演化经济学研究工具,基于央地分权的视角,将地方政府与中央政府两大主体同时纳入分析框架。根据复制动态方程探讨参与主体的行为演化特征和行为演化稳定策略,在模型求解的基础上,利用MATLAB仿真工具,分析不同情形下参与主体演化稳定策略的走向及其收敛趋势。研究发现,央地两级政府在环境规制策略执行过程中的动态演化,很大程度上取决于地方政府环境规制执行力度、成本、收益和损失以及中央政府监管力度、成本和处罚力度等因素的大小。因此,针对地方政府环境策略激励设计,应重点改革政绩考核机制,引入市场机制,并通过环保补贴、财政转移支付等手段降低地方政府环境规制执行成本;中央政府应通过调节政绩考核体系中的经济发展指标和环境指标的权重系数来加强对地方政府环境规制执行情况的监管力度,建立第三方监管机制以降低中央政府监管成本,制定合理的奖惩机制以提高监管效率;以期推动我国环境规制策略的高效执行,促进环境绩效向经济绩效的良性转换,实现双重帕累托改进。 相似文献
128.
Two means by which climate change may increase surface soil erosion in mountainous terrain are: (1) increasing the frequency of extreme rainfall events and (2) decreasing the duration of snow cover on bare soil. We used output from four general circulation models (GCMs) and two greenhouse gas trajectories to produce a suite of hydrologic variables at a daily time‐step for historic and projected 21st Century conditions. We statistically disaggregated the daily rainfall to hourly, using hourly rainfall from a network of nine weather stations in the Tahoe Basin, and filtered out rain falling on a snowpack. We applied published equations to convert hourly intensity to raindrop kinetic energy (KE) for each day and grid cell in the Basin, averaged across grid cells, and created time series of total annual and maximum annual hourly kinetic energy (TKE and MKE) on snow‐free ground. Using the Generalized Extreme Value distribution, we calculated the significance of long‐term trends in KE on snow‐free ground, and estimated energy levels for return periods of 2, 20, and 100 years. We then detrended the snowpack data and compared the resulting trends in KE with the trends resulting from changes in both rainfall energy and snowpack under two GCMs. Principal findings include (1) upward trends in MKE, (2) stronger upward trends in TKE; and (3) an effect of increasing rainfall intensities on KE in some cases, and a strong effect of reduced snowpack in all cases examined. 相似文献
129.
集中供热-缓解乌鲁木齐大气污染的有效途径 总被引:8,自引:1,他引:8
针对乌鲁木齐大气污染的现状,重点介绍了集中供热在治理城市大气污染中发挥的重要作用,阐明了推广热电联产、集中供热以及清洁能源对改善乌鲁木齐市空气环境质量的重要意义.指出在现阶段发展集中供热工程,仍将是缓解和改善乌鲁木齐大气污染的有效途径之一. 相似文献
130.
Designing environmental monitoring networks to measure extremes 总被引:1,自引:0,他引:1
Howard Chang Audrey Qiuyan Fu Nhu D. Le James V. Zidek 《Environmental and Ecological Statistics》2007,14(3):301-321
This paper discusses challenges arising in the design of networks for monitoring extreme values over the domain of a random environmental space-time field {X ij } i = 1, . . . , I denoting site and j = 1, . . . denoting time (e.g. hour). The field of extremes for time span r over site domain i = 1, . . . ,I is given by \(\{Y_{i(r+1)}=\max_{j=k}^{k+n-1} X_{ij}\}\) for k = 1 + rn, r = 0, . . . ,. Such networks must not only measure extremes at the monitored sites but also enable their prediction at the non-monitored ones. Designing such a network poses special challenges that do not seem to have been generally recognized. One of these problems is the loss of spatial dependence between site responses in going from the environmental process to the field of extremes it generates. In particular we show empirically that the intersite covariance Cov(Y i(r+1),Y i′(r+1)) can generally decline toward zero as r increases, for site pairs i ≠ i′. Thus the measured extreme values may not predict the unmeasured ones very precisely. Consequently high levels of pollution exposure of a sensitive group (e.g. school children) located between monitored sites may be overlooked. This potential deficiency raises concerns about the adequacy of air pollution monitoring networks whose primary role is the detection of noncompliance with air quality standards based on extremes designed to protect human health. The need to monitor for noncompliance and thereby protect human health, points to other issues. How well do networks designed to monitor the field monitor their fields of extremes? What criterion should be used to select prospective monitoring sites when setting up or adding to a network? As the paper demonstrates by assessing an existing network, the answer to the first question is not well, at least in the case considered. To the second, the paper suggests a variety of plausible answers but shows through a simulation study, that they can lead to different optimum designs. The paper offers an approach that circumvents the dilemma posed by the answer to the second question. That approach models the field of extremes (suitably transformed) by a multivariate Gaussian-Inverse Wishart hierarchical Bayesian distribution. The adequacy of this model is empirically assessed in an application by finding the relative coverage frequency of the predictive credibility ellipsoid implied by its posterior distribution. The favorable results obtained suggest this posterior adequately describes that (transformed) field. Hence it can form the basis for designing an appropriate network. Its use is demonstrated by a hypothetical extension of an existing monitoring network. That foundation in turn enables a network to be designed of sufficient density (relative to cost) to serve its regulatory purpose. 相似文献