全文获取类型
收费全文 | 2845篇 |
免费 | 343篇 |
国内免费 | 351篇 |
专业分类
安全科学 | 368篇 |
废物处理 | 23篇 |
环保管理 | 637篇 |
综合类 | 1035篇 |
基础理论 | 455篇 |
环境理论 | 54篇 |
污染及防治 | 112篇 |
评价与监测 | 126篇 |
社会与环境 | 335篇 |
灾害及防治 | 394篇 |
出版年
2024年 | 9篇 |
2023年 | 83篇 |
2022年 | 91篇 |
2021年 | 120篇 |
2020年 | 124篇 |
2019年 | 168篇 |
2018年 | 155篇 |
2017年 | 161篇 |
2016年 | 178篇 |
2015年 | 183篇 |
2014年 | 144篇 |
2013年 | 292篇 |
2012年 | 205篇 |
2011年 | 220篇 |
2010年 | 165篇 |
2009年 | 135篇 |
2008年 | 117篇 |
2007年 | 144篇 |
2006年 | 120篇 |
2005年 | 92篇 |
2004年 | 104篇 |
2003年 | 80篇 |
2002年 | 66篇 |
2001年 | 47篇 |
2000年 | 83篇 |
1999年 | 64篇 |
1998年 | 29篇 |
1997年 | 31篇 |
1996年 | 20篇 |
1995年 | 12篇 |
1994年 | 14篇 |
1993年 | 20篇 |
1992年 | 6篇 |
1991年 | 8篇 |
1990年 | 9篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 1篇 |
1984年 | 5篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1973年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有3539条查询结果,搜索用时 31 毫秒
261.
P. Gyau-Boakye 《Environment, Development and Sustainability》2001,3(1):17-29
The Akosombo dam was constructed on the Volta river primarily for the generation of hydropower. The resultant Volta lake which was formed between 1962 and 1966 in Ghana will probably long be one of the greatest man-made lakes. It produces 912MW of electricity at its maximum operating capacity. The Akosombo hydroelectric project (HEP) was meant among others to open up Ghana to rapid industrialization and hence modern development. Other positive impacts of the HEP include fishing, farming, transportation and tourism. However, there are equally negative impacts, some of which the project did not envisage and these are felt on the physical, biological and human subsystems within the immediate project environments and places much more distant from them. Recently, there have been declines in the lake levels resulting most probably from inadequate rainfall and/or runoff from the river catchments that feed the lake, and also from the observed rising temperatures. Comparisons of the runoff from two most important tributaries of the Volta (White Volta and Oti) for two time periods of 1951–1970 and 1971–1990 showed reductions in mean streamflows of 23.1% on the White Volta and 32.5% on the Oti. Similarly, a plot of the mean annual temperatures for the upper Volta basin indicated a 1^C rise in temperature from 1945–1993. 相似文献
262.
263.
秦皇岛市50年来气候变暖变干,年平均气温提高2.3℃,≥10℃年积温增加11.4%,无霜期延长22天,但年平均降水量却减少12.6%。这对农业和工业的影响弊大于利,对旅游业的影响则有利有弊。为此应趋利避害,加强水资源的开源节流,发展节水经济和循环经济,发展休闲度假旅游,延长旺季。 相似文献
264.
突发性环境污染事故具有不确定性,因此要求应急监测准备工作常备不懈;应急监测准备和响应贯穿于事前、事发、事后几个阶段,包括日常准备、应急监测、结果发布、跟踪监测、经验总结等主要环节。 相似文献
265.
266.
267.
268.
针对我国现行的民航灾害应急联动救援体系所存在着多头指挥、组织形式不明确、责任关系不协调、信息沟通不顺畅、资源调度不合理等问题,运用文献检索、理论分析与实地调研相结合的方法,笔者提出优化思路:民航灾害应急联动机制应以各级民航管理当局的飞行事故应急指挥部为主要指挥决策者,采用虚拟的网络式组织形式,理顺联动单位的责任与关系,将应急联动的信息网络与各地突发公共危机事件的信息平台接轨,成立全国统一的、具有双重功能的民航灾害应急资源调度中心。其中,对民航灾害应急联动虚拟网络组织形式的设计,较好地改进了现行组织的效率,体现了快速反应和协调行动的要求。 相似文献
269.
Fredrick W. Kaurish Tamim Younos 《Journal of the American Water Resources Association》2007,43(2):533-545
Abstract: There is a significant need for a science‐based approach to interpret water‐monitoring data and to facilitate the rapid transfer of information to water resource managers and the general public. The water quality Index (WQI) is defined as a single numeric score that describes the surface water quality condition at a particular time and location. The objective of this paper is to describe the WQI concept and the approach for developing an ecoregion‐specific standardized WQI that meets the needs described above. The premise of the proposed WQI is based on categorizing scientifically documented aquatic life responses to changes in instream water chemistry. The method uses an aggregated procedure that matches the entire range of standardized probable biological responses to standardized narrative water quality evaluation categories and standardized rank score categories. The calculation of WQI and decision‐making process are performed within an Excel spreadsheet software program. The article includes examples of the proposed WQI applications that could enhance effective water resource management and facilitate timely communication of water quality conditions to water resource managers and the general public. 相似文献
270.
Abstract: Identifying relationships between landscape hydrogeological setting, riparian hydrological functioning and riparian zone sensitivity to climate and water quality changes is critical in order to best use riparian zones as best management practices in the future. In this study, we investigate water table dynamics, water flow path and the relative importance of precipitation, deep ground water (DG) and seep water as sources of water to a riparian zone in a deeply incised glacial till valley of the Midwest. Data indicate that water table fluctuations are strongly influenced by soil texture and to a lesser extent by upland sediment stratigraphy producing seeps near the slope bottom. The occurrence of till in the upland and at 1.7‐2 m in the riparian zone contributes to maintaining flow parallel to the ground surface at this site. Lateral ground‐water fluxes at this site with a steep topography in the upland (16%) and loam soil near the slope bottom are small (<10 l/d/m stream length) and intermittent. A shift in flow path from a lateral direction to a down valley direction is observed in the summer despite the steep concave topography and the occurrence of seeps at the slope bottom. Principal component and discriminant analysis indicate that riparian water is most similar to seep water throughout the year and that DG originating from imbedded sand and gravel layers in the lower till unit is not a major source of water to riparian zones in this setting. Water quality data and the dependence of the riparian zone for recharge on seep water suggest that sites in this setting may be highly sensitive to changes in precipitation and water quality in the upland in the future. A conceptual framework describing the hydrological functioning of riparian zones on this setting is presented to generalize the finding of this study. 相似文献