全文获取类型
收费全文 | 9370篇 |
免费 | 829篇 |
国内免费 | 2299篇 |
专业分类
安全科学 | 404篇 |
废物处理 | 164篇 |
环保管理 | 1893篇 |
综合类 | 6595篇 |
基础理论 | 1144篇 |
环境理论 | 6篇 |
污染及防治 | 710篇 |
评价与监测 | 1094篇 |
社会与环境 | 432篇 |
灾害及防治 | 56篇 |
出版年
2024年 | 41篇 |
2023年 | 202篇 |
2022年 | 294篇 |
2021年 | 378篇 |
2020年 | 391篇 |
2019年 | 331篇 |
2018年 | 272篇 |
2017年 | 363篇 |
2016年 | 378篇 |
2015年 | 463篇 |
2014年 | 485篇 |
2013年 | 679篇 |
2012年 | 616篇 |
2011年 | 709篇 |
2010年 | 563篇 |
2009年 | 563篇 |
2008年 | 474篇 |
2007年 | 657篇 |
2006年 | 642篇 |
2005年 | 474篇 |
2004年 | 434篇 |
2003年 | 480篇 |
2002年 | 408篇 |
2001年 | 377篇 |
2000年 | 362篇 |
1999年 | 260篇 |
1998年 | 192篇 |
1997年 | 172篇 |
1996年 | 151篇 |
1995年 | 113篇 |
1994年 | 112篇 |
1993年 | 77篇 |
1992年 | 70篇 |
1991年 | 59篇 |
1990年 | 41篇 |
1989年 | 19篇 |
1988年 | 14篇 |
1987年 | 29篇 |
1986年 | 15篇 |
1985年 | 12篇 |
1984年 | 7篇 |
1982年 | 15篇 |
1981年 | 17篇 |
1980年 | 13篇 |
1979年 | 10篇 |
1978年 | 16篇 |
1977年 | 5篇 |
1973年 | 8篇 |
1972年 | 9篇 |
1971年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
71.
David L. Peterson 《Environmental monitoring and assessment》2000,64(1):81-91
A quantitatively robust yet parsimonious air-quality monitoring network in mountainous regions requires special attention to relevant spatial and temporal scales of measurement and inference. The design of monitoring networks should focus on the objectives required by public agencies, namely: 1) determine if some threshold has been exceeded (e.g., for regulatory purposes), and 2) identify spatial patterns and temporal trends (e.g., to protect natural resources). A short-term, multi-scale assessment to quantify spatial variability in air quality is a valuable asset in designing a network, in conjunction with an evaluation of existing data and simulation-model output. A recent assessment in Washington state (USA) quantified spatial variability in tropospheric ozone distribution ranging from a single watershed to the western third of the state. Spatial and temporal coherence in ozone exposure modified by predictable elevational relationships ( 1.3 ppbv ozone per 100 m elevation gain) extends from urban areas to the crest of the Cascade Range. This suggests that a sparse network of permanent analyzers is sufficient at all spatial scales, with the option of periodic intensive measurements to validate network design. It is imperative that agencies cooperate in the design of monitoring networks in mountainous regions to optimize data collection and financial efficiencies. 相似文献
72.
73.
Bertram P Stadler-Salt N Horvatin P Shear H;State of the Lakes Ecosystem Conferences 《Environmental monitoring and assessment》2003,81(1-3):27-33
Many administrative jurisdictions have authority over parts of the Great Lakes, sometimes with competing purposes as well as governance at differing scales of time and space. As demand increases for high quality information that is relevant to environmental managers, environmental and natural resource agencies with limited budgets must look to interdisciplinary, collaborative approaches for the collection, analysis and reporting of data. The State of the Lakes Ecosystem Conferences (SOLEC) were begun in 1994 in response to reporting requirements of the Great Lakes Water Quality Agreement between Canada and the U.S. The biennial conferences provide independent, science-based reporting on the state of health of the Great Lakes ecosystem components. A suite of indicators necessary and sufficient to assess Great Lakes ecosystem status was introduced in 1998, and assessments based on a subset of the indicators were presented in 2000. Because SOLEC is a multi-agency, multi-jurisdictional reporting venue, the SOLEC indicators require acceptance by a broad spectrum of stakeholders in the Great Lakes basin. The SOLEC indicators list is expected to provide the basis for government agencies and other organizations to collaborate more effectively and to allocate resources to data collection, evaluation and reporting on the state of the Great Lakes basin ecosystem. 相似文献
74.
This paper presents development of a first approximation of a Namibian, national level, land degradation monitoring system.
The process involved a large number of stakeholders and led to the definition of four primary indicators that were regarded
as related to land degradation in Namibia: population pressure, livestock pressure, seasonal rainfall and erosion hazards.
These indicators were calculated annually for the period 1971–1997. Annual land degradation risk maps were produced for the
same period by combining the indicators. A time series analysis of results generated by indicators was undertaken at two sites.
The analysis revealed a general trend towards an increased land degradation risk over the period 1971–1997. A decrease in
annual rainfall and an increase in livestock numbers caused this negative trend at one site, while decreased annual rainfall
and increased human population were the causes at a second site. Evaluation of resulting maps through direct field observations
and long-term monitoring at selected study sites with different conditions relevant for the indicators defined, is an essential
next step. 相似文献
75.
青铜峡铝厂氟污染对广武乡玉米影响的调查分析 总被引:1,自引:0,他引:1
监测了青铜峡铝厂东南方向4.5km的广武乡玉米叶,得知含氟量为43.94-166.1mg/kg,对照样品树新林场玉米叶的含氟均值为13.15mg/kg,广武乡的玉米受到了严重的氟污染,农作物减产严重。 相似文献
76.
77.
淮河流域污染"久治不愈"原因浅析及治理措施建议 总被引:9,自引:0,他引:9
根据淮河流域水质和产业结构现状、近几年来主要污染物排放量变化以及流域内污水处理情况,初步分析了淮河流域污染反弹“久治不愈”的几个原因并提出了几点相应的建议。 相似文献
78.
经济手段在环境管理中的作用及涉及到政府与各利益关系人之间的博弈过程。本文就政府与一次性餐具生产者,销售者之间的博弈关系,分析如何应用经济手段使其在防治“白色污染”中发挥更好的作用。 相似文献
79.
80.
阿图什市空气质量变化趋势分析 总被引:1,自引:0,他引:1
分析了阿图什市“八五”至“九五”期间空气质量监测数据不同年度、不同季节及不同污染因子的动态变化趋势.结合当地能源结构、气候特征、城市环境综合发展水平,指出影响阿图什市空气质量的主要因素,为防治和减轻阿图什市的空气污染提供了科学依据。 相似文献