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1.
The aim of this work is (1) to discuss approaches and tools to set management goals using operational indicators for coastal management (i.e., indicators that are easy to measure, understand and predict) and validated predictive models and (2) to discuss remedial strategies for sustainable coastal management regarding water quality and the abundance of fish, waterfowl and large aquatic plants. These approaches are exemplified using data from Ringkøbing Fjord, Denmark, which has undergone two major regime shifts during the last decades. This work discusses the changes taken place during the period from 1980 to 2004 (when there are good empirical data). For Ringkøbing Fjord, which is a very shallow, well-oxygenated lagoon dominated by resuspension processes, we have targeted on the following operational indicators, which are meant to reflect seasonal median values for the entire defined coastal area (the ecosystem scale) and not conditions at individual sites or data from shorter time periods: Secchi depth (as a standard measure of water clarity) and chlorophyll-a concentrations (as a key measure of algal biomass). The operational indicators are regulated by a set of standard abiotic factors, such as salinity, suspended particulate matter (SPM), nutrient concentrations (N and P), coastal morphometry and water exchange. Such relationships are quantified using well-tested, general quantitative models, which illustrate how these indicators are interrelated and how they reflect fundamental aspects of coastal ecosystems. We demonstrate that the regime shift in the lagoon can be modelled and quantitatively explained and is related to changes in salinity and nutrient inflow. A very important threshold is linked to increased salinities in the lagoon. For example, when the mean annual salinity is higher than about 9.5‰, large numbers of saltwater species of clams can survive and influence the structure and function of the ecosystem in profound ways. The model also illustrates the dynamic response to changes in nutrient loading. We have presented several management strategies with the goal of keeping the Secchi depth at 2 m, which would stimulate the growth of higher aquatic plants, which are fundamental for fish production and bird abundance in the lagoon. Given the fact that the Secchi depth depends on many variable factors (temperature, TP-inflow from land, salinity, changes in biomasses of macrophytes and clams, which are accounted for in these simulations), our results indicate that in practice it will likely be very difficult to reach that goal. However, it would be realistic to maintain a Secchi depth of 1.5 m if the variability in salinity is minimized and the mean salinity is kept at about 10.2‰. 相似文献
2.
Environmental risk perception, environmental concern and propensity to participate in organic farming programmes 总被引:4,自引:0,他引:4
This paper aims to identify the factors underlying farmers' propensity to participate in organic farming programmes in a Romanian rural region that confronts non-point source pollution. For this, we employ structural equation modelling with latent variables using a specific data set collected through an agri-environmental farm survey in 2001. The model includes one 'behavioural intention' latent variable ('propensity to participate in organic farming programmes') and five 'attitude' and 'socio-economic' latent variables ('socio-demographic characteristics', 'economic characteristics', 'agri-environmental information access', 'environmental risk perception' and 'general environmental concern'). The results indicate that, overall, the model has an adequate fit to the data. All loadings are statistically significant, supporting the theoretical basis for assignment of indicators for each latent variable. The significance tests for the structural model parameters show 'environmental risk perception' as the strongest determinant of farmers' propensity to participate in organic farming programmes. 相似文献
3.
为深入探索地铁应急疏散过程中疏散者的心理异质性及其路径选择行为机制,建立潜类别模型(LCM)。首先通过潜在剖面分析(LPA),利用心理潜变量将人群分类,并根据拟合指标确定最优心理潜类别数目;然后通过方差分析验证分类的可靠性;最后分析不同心理潜类别人群的路径选择偏好,对比模型预测路径选择结果与实际选择结果。研究表明:疏散者可分为5种心理潜类别,其中第3类人群只倾向于选择最短路径,第5类人群对最短路径的选择偏好近似于对不拥挤路径的选择偏好,其路径选择策略更加灵活;LCM相比于不分类的总体模型预测准确率更高,并且更加接近实际选择概率。 相似文献
4.
《Process Safety and Environmental Protection》2014,92(6):723-731
Recently production of hydrogen from water through the Cu–Cl thermochemical cycle is developed as a new technology. The main advantages of this technology over existing ones are higher efficiency, lower costs, lower environmental impact and reduced greenhouse gas emissions. Considering these advantages, the usage of this technology in new industries such as nuclear and oil is increasingly developed. Due to hazards involved in hydrogen production, design and implementation of hydrogen plants require provisions for safety, reliability and risk assessment. However, very little research is done from safety point of view. This paper introduces fault semantic network (FSN) as a novel method for fault diagnosis and fault propagation analysis by using evolutionary techniques like genetic programming (GP) and neural networks (NN), to uncover process variables’ interactions. The effectiveness, feasibility and robustness of the proposed method are demonstrated on simulated data obtained from the simulation of hydrogen production process in Aspen HYSYS®. The proposed method has successfully achieved reasonable detection and prediction of non-linear interaction patterns among process variables. 相似文献
5.
Kuei-Ying Huang Tzu-Han Chang Yung-ho Chiu Chih-Yu Yang Tai-Yu Lin 《Natural resources forum》2023,47(3):578-601
China is the country with the largest coal mining production and consumption in the world, but due to a large amount of coal burning, air pollution and climate change are exasperating related problems. The previous literature mainly has discussed coal mine production and environmental pollution, but failed to take into account external factors such as climate change and seldom discussed the relationship between coal mine land use and land restoration. Therefore, this study uses the meta-Epsilon-Based Measure two-stage Data Envelopment Analysis under the exogenous model and incorporates coal mine land use and land restoration use into the model to explore the relationship between the two under climate change. The research results are as follows. (1) If the external climate factors are not considered, then the phenomenon of overestimation or underestimation of the technology gap arises. (2) The efficiency value of the coal mining stage in most provinces is generally higher than the land restoration efficiency value. 相似文献
6.
7.
The exact distributions of the ratio X/Y are derived when X and Y are independent random variables and come from type I, type II or type III extreme value distributions. A detailed application of the results is provided to extreme rainfall data from Korea. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
8.
选择合适的多时相遥感影像合成方法以及建模变量对于土壤有机碳含量的估测及其空间分布反演具有重要作用. 以新疆博斯腾湖流域土壤有机碳含量为研究对象,按照最小值、中值以及均值Sentinel-2多时相卫星影像合成方法生成光谱变量,同时引入气候和地形等环境变量作为建模变量. 结合Boruta变量筛选算法和随机森林(RF)模型分析探究不同影像合成方法以及变量集合对耕层土壤有机碳含量估测的影响及差异. 结果表明:①环境变量结合光谱变量能够较好地估测土壤有机碳含量,环境变量中的气候变量对博斯腾湖流域土壤有机碳含量的建模估测发挥着关键作用;②相对于全变量集合,经过Boruta变量筛选算法后的特征变量模型估测精度要更好;③均值合成的影像光谱变量结合环境变量的建模效果最好,最优模型的估测精度R2为0.97,RMSE为2.919 g·kg-1,RPD为5.319. 使用Boruta变量筛选算法对多时相均值合成光谱变量与环境变量所建立的RF模型能够准确地实现博斯腾湖流域土壤有机碳含量的空间反演估测,为该流域土壤有机碳含量的准确估测提供技术支持. 相似文献
9.
隧道爆破振动影响因素的灰色关联分析 总被引:1,自引:1,他引:0
为优化隧道爆破方案,降低爆破振动危害,采用灰色关联分析法(GRA)对爆破振动的影响因素进行分析.首先确定振动速度、主振频率和振动持续时间作为系统特征变量,确定总药量、最大段药量、掏槽孔最大段药量、雷管段数、爆心距、最小延期间隔时间、临空面数等作为相关因素变量;再结合厦门某隧道爆破实测数据,进行灰色关联计算;然后对计算结果进行排序和优势分析,得到爆破振动影响因素的主次顺序,其中准优因素为爆心距,可控准优因素为雷管段数和掏槽眼最大段药量;最后对隧道爆破参数进行优化,测点爆破振速由1.2cm/8减小到0.74 cm/8,降振率达38.3%.结果表明,采用GRA确定爆破振动主要影响因素,为有效控制爆破振动提供理论依据. 相似文献
10.
面向粮食产量空间化的多元回归分析模型中的两个关键问题探讨 总被引:1,自引:0,他引:1
为比较不同区域尺度变量对模型拟合效果的影响,在全国不分区和分区两种情况下,分别基于县级和地市级两个区域尺度上的样本构建粮食产量与水田、水浇地、旱地面积之间的多元线性回归模型,结果显示,用地市级数据作分析样本比用县级数据作分析样本好,分区建模比不分区建模效果好。因此,将全国划分为7个区,以地市级数据作为区域尺度的变量,在区域、栅格、亚栅格三个尺度上探讨变量(因变量、自变量)尺度和常数项取值这两个因素对模型应用的影响。得到以下结论:1)基于区域尺度样本构建的多元回归模型,如果常数项不为0,则不能用于空间化计算;如果常数项为0,则可以用于空间化计算;2)基于栅格尺度样本构建的多元回归模型,不论常数项是否为0,均可应用于空间化计算;3)基于亚栅格尺度样本构建的多元回归模型,不论其常数项是否为0,也均可用于空间化计算,但需要将计算结果乘以一个系数,该系数等于栅格单元面积与亚栅格单元面积的比值。上述结论对其他类型的统计数据空间化具有指导和参考价值。 相似文献