全文获取类型
收费全文 | 2550篇 |
免费 | 74篇 |
国内免费 | 24篇 |
专业分类
安全科学 | 181篇 |
废物处理 | 151篇 |
环保管理 | 541篇 |
综合类 | 298篇 |
基础理论 | 586篇 |
环境理论 | 3篇 |
污染及防治 | 582篇 |
评价与监测 | 179篇 |
社会与环境 | 92篇 |
灾害及防治 | 35篇 |
出版年
2023年 | 13篇 |
2022年 | 19篇 |
2021年 | 27篇 |
2020年 | 26篇 |
2019年 | 26篇 |
2018年 | 61篇 |
2017年 | 58篇 |
2016年 | 76篇 |
2015年 | 72篇 |
2014年 | 70篇 |
2013年 | 231篇 |
2012年 | 108篇 |
2011年 | 148篇 |
2010年 | 114篇 |
2009年 | 131篇 |
2008年 | 127篇 |
2007年 | 143篇 |
2006年 | 133篇 |
2005年 | 97篇 |
2004年 | 85篇 |
2003年 | 107篇 |
2002年 | 71篇 |
2001年 | 54篇 |
2000年 | 53篇 |
1999年 | 41篇 |
1998年 | 39篇 |
1997年 | 34篇 |
1996年 | 33篇 |
1995年 | 26篇 |
1994年 | 34篇 |
1993年 | 31篇 |
1992年 | 21篇 |
1991年 | 24篇 |
1990年 | 13篇 |
1989年 | 11篇 |
1988年 | 16篇 |
1987年 | 19篇 |
1986年 | 13篇 |
1985年 | 19篇 |
1984年 | 12篇 |
1983年 | 18篇 |
1982年 | 19篇 |
1981年 | 24篇 |
1980年 | 13篇 |
1979年 | 10篇 |
1978年 | 6篇 |
1977年 | 9篇 |
1971年 | 6篇 |
1957年 | 5篇 |
1955年 | 5篇 |
排序方式: 共有2648条查询结果,搜索用时 0 毫秒
281.
Integrity of chloroplast membranes is essential to photosynthesis. Loss of thylakoid membrane integrity has been proposed as a consequence of ozone (O(3)) exposure and therefore may be a mechanistic basis for decreased photosynthetic rates commonly associated with ozone exposure. To investigate this hypothesis, Pinus ponderosa seedlings were exposed to ambient air or ozone concentrations maintained at 0.15 or 0.30 microliter l(-1) for 10 h day(-1) for 51 days during their second growing season. Over the course of the study, foliage samples were periodically collected for thylakoid membrane, chlorophyll and protein analyses. Additionally, gas-exchange measurements were made in conjunction with foliage sampling to verify that observed chloroplastic responses were associated with ozone-induced changes in photosynthesis.Needles exposed to elevated ozone exhibited decreases in chlorophyll a and b content. The decreases were dependent on the duration and intensity of ozone exposure. When based on equal amounts of chlorophyll, ozone-exposed sample tissue exhibited an increase in total protein. When based on equal amounts of protein, ozone-exposed samples exhibited an increase in 37 kDa proteins, possibly consisting of breakdown products, and a possible decrease in 68 kDa proteins, Rubisco small subunit. There was also a change in the ratio of Photosystem I protein complexes CPI and CPII that may have contributed to decreased photosynthesis. Net photosynthetic rates were decreased in the high ozone treatment suggesting that observed structural and biochemical changes in the chloroplast were associated with alterations of the photosynthetic process. 相似文献
282.
Local Agenda 21 (LA21) has emerged as the principal means of addressing sustainable development practice at the local government level. In the UK, progressive local authorities have emphasised the need for participatory processes and innovative policy options. This requires commitment and active involvement from a variety of individuals and organisations. Participants in LA21 have been interviewed to determine their motivations and perceptions, and their responses are represented in terms of the storylines of various constituencies of interest. The key themes seem to be those of actively promoting widespread participation, gaining competence in innovative techniques, taking a holistic approach to quality of life concerns, and claiming the legitimacy of local government as a key player in sustainable development. 相似文献
283.
Predicted increases in coral disease outbreaks associated with climate change have implications for coral reef ecosystems
and the people and industries that depend on them. It is critical that coral reef managers understand these implications and
have the ability to assess and reduce risk, detect and contain outbreaks, and monitor and minimise impacts. Here, we present
a coral disease response framework that has four core components: (1) an early warning system, (2) a tiered impact assessment
program, (3) scaled management actions and (4) a communication plan. The early warning system combines predictive tools that
monitor the risk of outbreaks of temperature-dependent coral diseases with in situ observations provided by a network of observers
who regularly report on coral health and reef state. Verified reports of an increase in disease prevalence trigger a tiered
response of more detailed impact assessment, targeted research and/or management actions. The response is scaled to the risk
posed by the outbreak, which is a function of the severity and spatial extent of the impacts. We review potential management
actions to mitigate coral disease impacts and facilitate recovery, considering emerging strategies unique to coral disease
and more established strategies to support reef resilience. We also describe approaches to communicating about coral disease
outbreaks that will address common misperceptions and raise awareness of the coral disease threat. By adopting this framework,
managers and researchers can establish a community of practice and can develop response plans for the management of coral
disease outbreaks based on local needs. The collaborations between managers and researchers we suggest will enable adaptive
management of disease impacts following evaluating the cost-effectiveness of emerging response actions and incrementally improving
our understanding of outbreak causation. 相似文献
284.
Paul Harvey 《Disasters》1998,22(3):200-217
The paper examines the challenge of rehabilitation from complex political emergencies (CPEs) and identifies a strategy that is characterised as a civil society rebuilding approach. It focuses on Somalia and a case study of a CARE project that aims to build the capacity of local NGOs. The paper argues that civil society in CPEs is simultaneously being undermined and contested by warring parties and emerging after state collapse. The scope of the paper is limited to one case study and that case study examines only a single aspect of civil society: national and international NGOs. The paper therefore presents tentative and preliminary results based on limited research. However, in reviewing the literature and presenting a way of approaching the subject, it aims to suggest a starting-point for developing a theoretical framework for such research. The paper finds that international agencies have tended to focus on civil society institutions simply as conduits for aid money and that this has tended to create organisations which lack downward accountability, are dependent on donors and are not addressing the wider roles for civil society envisaged in the approach. Rebuilding civil society does hold out the promise of giving non-military interests a stronger voice and starting a process of changing the aid delivery culture. Achieving these objectives, however, will be a slow and largely indigenous process and there is a need for lowered expectations about what outside assistance can achieve 相似文献
285.
Paul J. Favara Todd M. Krieger Bob Boughton Angela S. Fisher Mohit Bhargava 《补救:环境净化治理成本、技术与工艺杂志》2011,21(3):39-79
The US Sustainable Remediation Forum (SURF) proposes a nine‐step process for conducting and documenting a footprint analysis and life‐cycle assessment (LCA) for remediation projects. This guidance is designed to assist remediation practitioners in evaluating the impacts resulting from potential remediation activities so that preventable impacts can be mitigated. Each of the nine steps is flexible and scalable to a full range of remediation projects and to the tools used by remediation practitioners for quantifying environmental metrics. Two fictional case studies are presented to demonstrate how the guidance can be implemented for a range of evaluations and tools. Case‐study findings show that greater insight into a study is achieved when the nine steps are followed and additional opportunities are provided to minimize remediation project footprints and create improved sustainable remediation solutions. This guidance promotes a consistent and repeatable process in which all pertinent information is provided in a transparent manner to allow stakeholders to comprehend the intricacies and tradeoffs inherent in a footprint analysis or LCA. For these reasons, SURF recommends that this guidance be used when a footprint analysis or LCA is completed for a remediation project. © 2011 Wiley Periodicals, Inc. 相似文献
286.
New fossil spiders (Arachnida: Araneae) from Middle Jurassic (ca. 165 Ma) strata of Daohugou, Inner Mongolia, China are described as Eoplectreurys gertschi gen. et sp. nov. and referred to the modern haplogyne family Plectreuridae. This small family is restricted to southwestern USA, Mexico, and the adjacent Caribbean area today and hitherto has only a sparse Cenozoic fossil record. The morphology of Eoplectreurys is remarkably similar to modern forms and thus demonstrates great evolutionary conservatism. This new discovery not only extends the fossil record of the family by at least 120 Ma to the Middle Jurassic but also supports the hypothesis of a different distribution of the family in the past than today and subsequent extinction over much of its former range. 相似文献
287.
Paul E. Spector 《组织行为杂志》2012,33(2):151-152
This paper introduces a Journal of Organizational Behavior point/counterpoint exchange (this issue) that focuses on the appropriate level of aggregation primarily in the assessment of personality in general and core self‐evaluations (CSE) in particular. Gilad Chen reviews arguments for and against the higher‐order construct of CSE, offering a number of recommendations for strengthening it. Timothy Judge and John Kammeyer‐Mueller offer a defense of CSE, and then extend the discussion to the measurement of other constructs beyond the personality domain. Together these two papers provide important insights about the appropriate level of aggregation of individual measures, and situations in which higher‐order versus lower‐order measures might be preferred. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
288.
Use of geographic information systems for assessing groundwater pollution potential by pesticides in Central Thailand 总被引:12,自引:0,他引:12
This study employed geographic information systems (GIS) technology to evaluate the vulnerability of groundwater to pesticide pollution in Thailand. The study area included three provinces, Kanchana Buri, Ratcha Buri, and Suphan Buri, located in west-central Thailand. Factors used for the vulnerability assessment included soil texture, slope, land use, well depth, and rainfall. These vulnerability factors were reclassified to a common scale, and a weighted average was computed to yield a vulnerability score. Vulnerability factors and weights were assigned considering pesticide concentrations in 90 wells throughout the study area. Well depth was the most significant vulnerability factor. Groundwater vulnerability maps were generated for several pesticides. The eastern, agricultural part of the study area has relatively deep wells and fine soils. Shallow wells are present in the mountainous west; however, fewer pesticides are applied in that region. Consequently, much of the study area had a medium groundwater vulnerability rating, although there were pockets of high vulnerability, for example, in agricultural areas with shallow wells. The groundwater vulnerability maps are effective for identifying locations warranting more detailed groundwater pollution and vulnerability investigations. 相似文献
289.
Paul A.Steenhof 《中国人口.资源与环境(英文版)》2005,3(2)
1 INTRODUCTIONEnergy and environmental issues in China have receivedsignificant attention in both the peer-reviewed literatureand in international energy and environmental policymaking in the last number of years. China's coal dominatedenergy consumption results in significant regional pollutionproblems, most notably acid rain that affects nearly 1/3rdof China's landmass and air pollution that plagues manyof its major cities. China now ranks as the top emitterof sulphur dioxide (SO2) pol… 相似文献
290.
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