全文获取类型
收费全文 | 526篇 |
免费 | 52篇 |
国内免费 | 92篇 |
专业分类
安全科学 | 54篇 |
废物处理 | 11篇 |
环保管理 | 88篇 |
综合类 | 273篇 |
基础理论 | 111篇 |
污染及防治 | 22篇 |
评价与监测 | 45篇 |
社会与环境 | 59篇 |
灾害及防治 | 7篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 14篇 |
2021年 | 19篇 |
2020年 | 13篇 |
2019年 | 16篇 |
2018年 | 10篇 |
2017年 | 19篇 |
2016年 | 17篇 |
2015年 | 34篇 |
2014年 | 26篇 |
2013年 | 40篇 |
2012年 | 41篇 |
2011年 | 41篇 |
2010年 | 39篇 |
2009年 | 38篇 |
2008年 | 34篇 |
2007年 | 35篇 |
2006年 | 35篇 |
2005年 | 36篇 |
2004年 | 23篇 |
2003年 | 18篇 |
2002年 | 12篇 |
2001年 | 21篇 |
2000年 | 17篇 |
1999年 | 12篇 |
1998年 | 17篇 |
1997年 | 8篇 |
1996年 | 3篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1981年 | 2篇 |
排序方式: 共有670条查询结果,搜索用时 15 毫秒
231.
Indicators for hydraulic and pollution retention assessment of stormwater infiltration basins 总被引:1,自引:0,他引:1
Infiltration basins are frequently used for stormwater management even though their long-term evolution is not well understood nor controlled. The two main problems encountered are clogging which compromises the hydraulic capacity of the basin and possible contamination of underlying soil and groundwater. This paper defines a framework for evaluating the hydraulic and pollution retention performance of infiltration basins in the long-term. Sets of context and performance indicators are proposed, along with two complementary modes of evaluation. Context indicators are identified in order to define the clogging and contamination states of the basins. Performance indicators are developed to assess several aspects of basin performance: drainage duration, overflow frequency, predictive life period, particle filtration and pollution trapping. Modes of evaluation include field investigation and long-term simulation modeling. Indicators are tested on five infiltration basins in suburban Lyon (France). Both context indicators and hydraulic performance indicators are reliable and their evaluation is representative of basin behavior. This is not the case for pollution retention performance indicators. Their assessment is difficult because of data quality. Field data has high uncertainties. The model is satisfactory for the hydraulic simulation and the evolution of clogging. Improvements are necessary for pollution flow simulation and the acquisition of better quality data is required. 相似文献
232.
辽宁省干线公路网络通达性研究 总被引:1,自引:0,他引:1
以辽宁省干线公路网络和14个地市、21个主要县市为研究对象,以最短距离原则为基础,选取距离、时间和通达性系数来衡量城市通达性水平的高低;以行车速度为指标,得到不同速度下通达性水平的空间格局;在100km/h的行车速度下,计算一个城市在1h、2h、3h、5h内连接的城市数目,并对通达性水平的特点和空间格局进行分析。结果显示,35个城市的通达性水平呈现出"同心圈"结构,"核心—外围"模式明显。以沈阳和鞍山为核心,由核心向外围通达性水平逐步降低,且随着行车速度的提高,通达性水平呈现出明显的上升趋势。由于通达水平的提高,在未来的几年里辽宁省将逐渐形成5个交通圈,同时实现"一个工作日,全省通达"的目标。 相似文献
233.
Antonio Bucci Vincenzo Alloc Gino Naclerio Giovanni Capobianco Fabio Divino Francesco Fiorillo Fulvio Celico 《环境科学学报(英文版)》2015
The aim of the research was to evaluate, at site scale, the influence of freezing and freeze/ thaw cycles on the survival of faecal coliforms and faecal enterococci in soil, in a climate change perspective. Before the winter period and during grazing, viable cells of faecal coliforms and faecal enterococci were detected only in the first 10 cm below ground, while, after the winter period and before the new seasonal grazing, a lower number of viable cells of both faecal indicators was detected only in some of the investigated soil profiles, and within the first 5 cm. Taking into consideration the results of specific investigations, we hypothesise that the non-uniform spatial distribution of grass roots within the studied soil can play an important role in influencing this phenomenon, while several abiotic factors do not play any significant role. Taking into account the local trend in the increase of air temperature, a different distribution of microbial pollution over time is expected in spring waters, in future climate scenarios. The progressive increase in air temperature will cause a progressive decrease in freeze/thaw cycles at higher altitudes, minimising cold shocks on microbial cells, and causing spring water pollution also during winter. 相似文献
234.
235.
生态城市建设的基本思路及其指标体系的评价标准 总被引:47,自引:0,他引:47
根据生态城市的基本内涵,提出生态城市建设的基本思路,运用专家咨询等方法从100多项有关指标中筛选出44个主要指标,构成能反映生态城市建设进程的相对完整的指标体系,并提出各指标因子的量化评价标准值。 相似文献
236.
贵阳市循环经济发展度量的研究 总被引:16,自引:0,他引:16
循环经济指标体系旨在度量区域循环经济发展的系统目标和工作进展。该文在“驱动力-压力-状态-响应”(DPSR)框架下设计度量区域循环经济发展的指标体系,含有状态指标、压力指标、驱动力指标、响应指标以及分离指标共5类指标集合。其中,分离指标集合作为循环经济的特征指标来表征经济发展与资源投入和污染产出分离的效果和趋势。考察贵阳循环经济规划案例表明:贵阳如果走循环经济的发展道路,可以转变经济增长方式,实现经济增长与资源投入和污染产出的分离。 相似文献
237.
传统的区域竞争力评价主要是侧重于经济指标,对生态环境要素涉及较少,在经济快速发展地区,生态环境已成为保证区域发展的重要基础条件。以安徽沿江地区为例,提出了生态环境竞争力的概念。以县(市、区)为评价基本单元,从生态环境压力、生态环境现状、经济发展需求和主动协调能力4个方面,设计了区域生态竞争力的评价指标体系,将各单元的生态环境竞争力水平分为5个等级:水平较高的地区主要位于南部、西部山地和合肥市区,竞争力水平较低的地区主要分布在和县-无为平原传统农业区和马鞍山、铜陵重工业区。生态环境竞争力不仅与自然生态系统的本底质量有关,也与区域经济技术水平、生态环境建设的投入水平、管理水平有关。最后对各区生态环境存在问题和提升优化途径进行了讨论。 相似文献
238.
Vegetation-permafrost relationships in the zone of sporadic permafrost distribution in the Kamchatka Peninsula 总被引:1,自引:0,他引:1
Studies on vegetation and permafrost table depth in the zone of sporadic permafrost distribution in the Uksichan River valley (the central Kamchatka Peninsula) have provided evidence that these components of biogeocenosis are interrelated and develop coordinately. In open larch forests with green forest mosses dominating in the ground vegetation layer, the permafrost table lies approximately 60 cm below the soil surface. When the ground vegetation layer is dominated by sphagnums, the permafrost table rises to 40–20 cm. In areas with a dwarf shrub-lichen ground layer, the soil thaw depth increases. A hypothesis is proposed that cyclic successional replacement of plant communities may take place in open larch forests on permafrost soils, including four consecutive stages with dominance of green mosses, sphagnums, lichens, and dwarf shrubs. In areas disturbed by fires, pioneer moss or herbaceous communities develop in the ground layer. 相似文献
239.
Lam K.C. 《中国人口.资源与环境(英文版)》2004,2(2)
The paper demonstrates why it is necessary to take the restoration of marine coastal ecosystem health as a new goal for integrated catchment management, in coastal area of the Tolo Harbour. The present goal of integrated catchment management (ICM) in the Tolo Harbour is to meet with Water Quality Objectives. The performance of an ICM plan, Tolo Harbour Action Plan (THAP), is evaluated by using marine coastal ecosystem health indicators including stress indicators and responses indicators. Since the implementation of THAP in 1988, some significant reduction in pollution loading has been observed - reduction of 83 % of BOD load and 82 % of TN between 1988 and 1999. There has been an improvement in the health state of Tolo Harbour marine coastal ecosystem as evidenced in the trends of the physical, chemical and biological indicators, although some reverse fluctuations in some periods exist. However, this can only be considered as the first sign of the ecosystem health restoration, since ecosystem health co 相似文献
240.
Chen Ying Zhao Yong & Liu ChangmingSchool of Environment Beijing Normal University State Key Joint Laboratory of Environment Simulation Pollution Control Beijing ChinaChina Institute of Water Resources Hydraulic Research Beijing China 《中国人口.资源与环境(英文版)》2004,2(2)
Water saving and developing water conservation society are the two key strategies both for wise water allocation and sustainable utilization. The paper analyses the connotation of water saving and water conservation society. Essentially, water saving means freeing up water from non-beneficial uses and providing it to some more productive uses. Basic principles for setting indicator are presented by providing efficient use of water, considering social issues and ecological protection. An integrated assessing water saving system aiming at more sustainable and efficient consumption is given considering unbalanced social and economic development in regions and basins. The hierarchy indicator system provides qualified tools to the practice of water conservation and evaluates the value for water conservation society construction. 相似文献