全文获取类型
收费全文 | 2186篇 |
免费 | 67篇 |
国内免费 | 43篇 |
专业分类
安全科学 | 81篇 |
废物处理 | 77篇 |
环保管理 | 455篇 |
综合类 | 267篇 |
基础理论 | 674篇 |
环境理论 | 6篇 |
污染及防治 | 447篇 |
评价与监测 | 143篇 |
社会与环境 | 118篇 |
灾害及防治 | 28篇 |
出版年
2023年 | 20篇 |
2022年 | 37篇 |
2021年 | 47篇 |
2020年 | 38篇 |
2019年 | 37篇 |
2018年 | 64篇 |
2017年 | 77篇 |
2016年 | 81篇 |
2015年 | 85篇 |
2014年 | 80篇 |
2013年 | 184篇 |
2012年 | 99篇 |
2011年 | 156篇 |
2010年 | 109篇 |
2009年 | 112篇 |
2008年 | 157篇 |
2007年 | 138篇 |
2006年 | 112篇 |
2005年 | 84篇 |
2004年 | 77篇 |
2003年 | 63篇 |
2002年 | 47篇 |
2001年 | 27篇 |
2000年 | 23篇 |
1999年 | 28篇 |
1998年 | 27篇 |
1997年 | 21篇 |
1996年 | 20篇 |
1995年 | 24篇 |
1994年 | 29篇 |
1993年 | 21篇 |
1992年 | 22篇 |
1991年 | 11篇 |
1990年 | 15篇 |
1989年 | 17篇 |
1988年 | 13篇 |
1987年 | 10篇 |
1986年 | 12篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 9篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1973年 | 2篇 |
1968年 | 4篇 |
排序方式: 共有2296条查询结果,搜索用时 15 毫秒
1.
Regional Environmental Change - Agro-ecosystem energy profiles reveal energy flows into, within, and out of US Great Plains farm communities across 140 years. This study evaluates external... 相似文献
2.
3.
4.
5.
A new, simple method for directly measuring activated sludge density was developed and applied, and the effects of biomass density on activated sludge settling in full-scale systems were evaluated. The driving force of sedimentation is the physical weight of the biological solids, but the role of biomass density in sedimentation has been largely ignored. Biomass density varied amongst treatment systems and this variability was correlated with settleability. Floc densities were approximately normally distributed within individual samples. Nonsoluble phosphorus content was a major contributor to density, and plants with enhanced biological phosphorus removal (EBPR) configurations generally had higher densities and better settleability than non-EBPR plants with similar filament contents. These results suggest that future work may benefit from consideration of density as a factor affecting activated sludge settling. 相似文献
6.
7.
Henrietta M. Lidiard Joy E. Rae Andrew Parker 《Environmental geochemistry and health》1993,15(2-3):93-104
A number of Mn-oxide minerals in soils from a farm in North Devon have been tentatively identified using a combination of
advanced analytical techniques: scanning electron microscopy (SEM), scanning electron microprobe (SEMP), X-ray diffraction
(XRD) and bulk chemical analysis by wet digestion followed by inductively-coupled plasma spectrometry (ICP). The minerals
lithiophorite and hollandite are thought to occur throughout the study area although there is considerable geographical variation
in the proportions of minerals present. Bimessite, vernadite, romanechite, todorokite and cryptomelane may also be present,
although in smaller amounts.
The use of SEMP, together with a simple sorption experiment, has allowed a study of the extent of uptake of Co and Cu by different
Mn-oxide minerals. Lithiophorite appears to take up Co and Cu more effectively than hollandite within a pH range of 4–6. 相似文献
8.
Evolution of environmental impact assessment as applied to watershed modification projects in Canada
Herman J. Dirschl Nicholas S. Novakowski M. Husain Sadar 《Environmental management》1993,17(4):545-555
This article reviews the application of environmental impact assessment (EIA) procedures and practices to three watershed
modification projects situaled in western Canada. These ventures were justified for accelerating regional economic development,
and cover the period during which public concerns for protecting the environment rapidly made their way into the national
political agenda. An historical account and analysis of the situation, therefore, seems desirable in order to understand the
development of EIA processes, practices, and methodologies since the start of construction of the first project in 1961. This
study concludes that there has been good progress in predicting and evaluating environmental and related social impacts of
watershed modification proposals. However, a number of obstacles need to be overcome before EIA can firmly establish itself
as an effective planning tool. These difficulties include jurisdictional confusions and conflicts, division of authority and
responsibility in designing and implementing appropriate mitigative and monitoring measures, lack of tested EIA methodologies,
and limited availability of qualified human resources. A number of conclusions and suggestions are offered so that future
watershed modification proposals may be planned and implemented in a more environmentally sustainable fashion. These include:
(1) EIA processes must be completed before irrevocable decisions are made. (2) Any major intrusion into a watershed is likely
to impact on some major components of the ecosystem(s). (3) Mitigation costs must form part of the benefit-cost analysis of
any project proposal. (4) Interjurisdictional cooperation is imperative where watersheds cross political boundaries. (5) The
EIA process is a public process, hence public concerns must be dealt with fairly. (6) The role of science in the EIA process
must be at arms length from project proponents and regulators, and allowed to function in the interest of the protection of
the environment and public health and safety.
The views expressed here are the authors’ own and do not necessarily reflect those of FEARO and/or other government agencies
and officials involved in the review of these projects. 相似文献
9.
The occurrence and impact of psychological contract violations were studied among graduate management alumni (N = 128) who were surveyed twice, once at graduation (immediately following recruitment) and then two years later. Psychological contracts, reciprocal obligations in employment developed during and after recruitment, were reported by a majority of respondents (54.8 per cent) as having been violated by their employers. The impact of violations are examined using both quantitative and qualitative data. Occurrence of violations correlated positively with turnover and negatively with trust, satisfaction and intentions to remain. 相似文献
10.