全文获取类型
收费全文 | 8725篇 |
免费 | 639篇 |
国内免费 | 271篇 |
专业分类
安全科学 | 1751篇 |
废物处理 | 138篇 |
环保管理 | 3344篇 |
综合类 | 2268篇 |
基础理论 | 878篇 |
环境理论 | 10篇 |
污染及防治 | 276篇 |
评价与监测 | 343篇 |
社会与环境 | 345篇 |
灾害及防治 | 282篇 |
出版年
2024年 | 92篇 |
2023年 | 183篇 |
2022年 | 163篇 |
2021年 | 242篇 |
2020年 | 315篇 |
2019年 | 247篇 |
2018年 | 204篇 |
2017年 | 261篇 |
2016年 | 321篇 |
2015年 | 268篇 |
2014年 | 322篇 |
2013年 | 469篇 |
2012年 | 549篇 |
2011年 | 575篇 |
2010年 | 393篇 |
2009年 | 500篇 |
2008年 | 363篇 |
2007年 | 476篇 |
2006年 | 477篇 |
2005年 | 362篇 |
2004年 | 393篇 |
2003年 | 299篇 |
2002年 | 279篇 |
2001年 | 271篇 |
2000年 | 271篇 |
1999年 | 206篇 |
1998年 | 133篇 |
1997年 | 135篇 |
1996年 | 109篇 |
1995年 | 108篇 |
1994年 | 50篇 |
1993年 | 62篇 |
1992年 | 57篇 |
1991年 | 47篇 |
1990年 | 34篇 |
1989年 | 27篇 |
1988年 | 34篇 |
1987年 | 33篇 |
1986年 | 28篇 |
1985年 | 23篇 |
1984年 | 27篇 |
1983年 | 19篇 |
1982年 | 22篇 |
1981年 | 18篇 |
1980年 | 25篇 |
1979年 | 33篇 |
1978年 | 21篇 |
1973年 | 14篇 |
1972年 | 16篇 |
1971年 | 14篇 |
排序方式: 共有9635条查询结果,搜索用时 15 毫秒
91.
Francisco Olivera Milver Valenzuela R. Srinivasan Janghwoan Choi Hiudae Cho Srikanth Koka Ashish Agrawal 《Journal of the American Water Resources Association》2006,42(2):295-309
This paper presents ArcGIS‐SWAT, a geodata model and geographic information system (GIS) interface for the Soil and Water Assessment Tool (SWAT). The ArcGIS‐SWAT data model is a system of geodatabases that store SWAT geographic, numeric, and text input data and results in an organized fashion. Thus, it is proposed that a single and comprehensive geodatabase be used as the repository of a SWAT simulation. The ArcGIS‐SWAT interface uses programming objects that conform to the Component Object Model (COM) design standard, which facilitate the use of functionality of other Windows‐based applications within ArcGIS‐SWAT. In particular, the use of MS Excel and MATLAB functionality for data analysis and visualization of results is demonstrated. Likewise, it is proposed to conduct hydrologic model integration through the sharing of information with a not‐model‐specific hub data model where information common to different models can be stored and from which it can be retrieved. As an example, it is demonstrated how the Hydrologic Modeling System (HMS) ‐ a computer application for flood analysis ‐ can use information originally developed by ArcGIS‐SWAT for SWAT. The application of ArcGIS‐SWAT to the Seco Creek watershed in Texas is presented. 相似文献
92.
Aaron C. Kite‐Powell Anna K. Harding 《Journal of the American Water Resources Association》2006,42(4):975-987
ABSTRACT: Approximately 4.5 million people in the United States who rely on well water are exposed to nitrate‐N concentrations exceeding the 10 mg/l standard. In this study in the Southern Willamette Valley in Oregon we reassessed nitrate‐N in rural wells sampled in 2000–2001, compared nitrate‐N concentrations among geological units, and surveyed residents about their perceptions of well water quality. Nitrate‐N concentrations were again sampled in 2002 and found to have increased significantly from the previous period. With rapid population growth in the area, the potential health risk in drinking well water that exceeds 10 mg/l nitrate‐N warrants continued public education. Nitrate‐N concentrations were found to be higher in the Holocene alluvium of the Willamette River and the Pleistocene sand and gravel post‐Missoula Flood deposits. Researchers conducting future studies may choose to stratify and monitor wells by geologic unit and by other parameters that estimate input of nutrients to the environment. Opinions differed between agricultural landowners and nonagricultural landowners with regard to the impact that agricultural fertilizers may have on water quality. Participants were supportive of a range of regulatory actions that might be used by homeowners or landowners to address ground water contamination. Given that the area is now designated a Groundwater Management Area, understanding local stakeholders’perceptions is critical and strategic and has the potential to help public agencies manage potential conflicts of opinion among stakeholders, build consensus, and help guide the approach to restoring ground water quality. 相似文献
93.
William Heasom Robert G. Traver Andrea Welker 《Journal of the American Water Resources Association》2006,42(5):1329-1347
ABSTRACT: The goal of this research was to develop a methodology for modeling a bioinfiltration best management practice (BMP) built in a dormitory area on the campus of Villanova University in Pennsylvania. The objectives were to quantify the behavior of the BMP through the different seasons and rainfall events; better understand the physical processes governing the system's behavior; and develop design criteria. The BMP was constructed in 2001 by excavating within an existing traffic island, backfilling with a sand/soil mixture, and planting with salt tolerant grasses and shrubs native to the Atlantic shore. It receives runoff from the asphalt (0.26 hectare) and turf (0.27 hectare) surfaces of the watershed. Monitoring supported by the hydrologic model shows that the facility infiltrates a significant fraction of the annual precipitation, substantially reducing the delivery of nonpoint source pollution and erosive surges downstream. A hydrologic model was developed using HEC‐HMS to represent the site and the BMP using Green‐Ampt and kinematic wave methods. Instruments allow comparison of the modeled and measured water budget parameters. The model, incorporating seasonally variable parameters, predicts the volumes infiltrated and bypassed by the BMP, confirming the applicability of the selected methods for the analysis of bioinfiltration BMPs. 相似文献
94.
95.
Analysis tools that combine large spatial and temporal scales are necessary for efficient management of wildlife species,
such as the burrowing owl (Athene cunicularia). We assessed the ability of Ripley’s K-function analysis integrated into a geographic information system (GIS) to determine changes in burrowing owl nest clustering
over two years at NASA Ames Research Center. Specifically, we used these tools to detect changes in spatial and temporal nest
clustering before, during, and after conducting management by mowing to maintain low vegetation height at nest burrows. We
found that the scale and timing of owl nest clustering matched the scale and timing of our conservation management actions
over a short time frame. While this study could not determine a causal link between mowing and nest clustering, we did find
that Ripley’s K and GIS were effective in detecting owl nest clustering and show promise for future conservation uses. 相似文献
96.
Ben A. Minteer Elizabeth A. Corley 《Journal of Agricultural and Environmental Ethics》2007,20(4):307-333
Few disputes in the annals of US environmentalism enjoy the pedigree of the conservation-preservation debate. Yet, although
many scholars have written extensively on the meaning and history of conservation and preservation in American environmental
thought and practice, the resonance of these concepts outside the academic literature has not been sufficiently examined.
Given the significance of the ideals of conservation and preservation in the justification of environmental policy and management,
however, we believe that a more detailed analysis of the real-world use and understanding of these ideas is needed. In this
paper, we describe the results of a qualitative, semantic study of the concepts of conservation and preservation undertaken
in the context of the Chattahoochee National Forest (CNF), located in northern Georgia (USA). Thirty in-depth interviews were
conducted with scientists and north Georgia residents either interested or involved in the future management of the forest.
Respondents were asked to define conservation and preservation in their own words and to indicate which approach they felt
was more appropriate for the management of the CNF. Qualitative content analysis was used to elicit a set of recurring themes
for each foundational concept. Taken together, these themes help to flesh out the meaning of conservation and preservation
for citizens and scientists today, and illustrate the evolving nature of two of the more significant and venerable ideas animating
US environmental policy and management. 相似文献
97.
Copper is the biocide of choice for present-day antifouling (AF) paints. It is also a major source of copper loading in to
the marine environment and, as such, might cause local copper levels to exceed water quality criteria. The present study is
multifaceted and looks into the overall impact of copper-based AF paints on copper concentrations along a 64-km stretch of
the Indian River Lagoon and at Port Canaveral, Florida. This preliminary study is one of the first to outline issues and present
background evidence on the current status of copper and copper-based AF usage in Florida and to address the need for management.
Previous measurements of copper levels in these waters show a history of copper contamination close to marinas, boatyards,
and at Port Canaveral that often exceed state and federal water quality standards. Further, we estimate that the total annual
copper input into the Indian River Lagoon is between 1.7 tons/year (sailboats) and 2.1 tons/year (powerboats) from boats in
14 marinas. We estimate the copper input into Port Canaveral to be about 1.4 tons/year from seven cruise ships. A brief survey
of marina operators and boat owners revealed attitudes and practices associated with AF paint usage that ranged from excellent
to inferior. Management recommendations are made for a proactive approach to improving AF paint selection and application,
assessing the environmental status of copper, and redefining existing management practices for sustainable AF paint usage
and environmental health. 相似文献
98.
Langeveld JW Verhagen A Neeteson JJ van Keulen H Conijn JG Schils RL Oenema J 《Journal of environmental management》2007,82(3):363-376
Intensive agriculture, characterized by high inputs, has serious implications on the environment. Monitoring and evaluation of projects aiming at designing, testing and applying more sustainable practices require instruments to asses agronomic as well as environmental performance. Guidelines for Good Agricultural Practice (GAP) or Good Farming Practice (GFP) define sustainable practices but give limited insight into their environmental performance. Agri-environmental indicators (AEIs) provide information on environmental as well as agronomic performance, which allows them to serve as analytical instruments in research and provide thresholds for legislation purposes. Effective AEIs are quantifiable and scientifically sound, relevant, acceptable to target groups, easy to interpret and cost-effective. This paper discusses application of four AEIs for nitrogen (N) management in three Dutch research projects: 'De Marke', 'Cows and Opportunities' and 'Farming with a future'. 'De Marke' applied Nitrogen Surplus and Groundwater Nitrate Concentration in the design and testing of environmentally sound dairy systems. 'Cows and Opportunities', testing and disseminating dairy systems designed at 'De Marke', mainly applied Nitrogen Surplus, while 'Farming with a future' used Nitrogen Surplus, Groundwater Nitrate Concentration and Residual Mineral Soil Nitrogen to support arable farmers in complying with Dutch legislation (MINAS). Nitrogen Surplus is quantifiable, appealing and easy to interpret, but lacks scientific soundness or a good relationship with groundwater quality. Nitrogen Use Efficiency is sensitive to changes in management, while Residual Mineral Soil Nitrogen is appealing and cheap, but has difficulties in scaling. Groundwater Nitrate Concentration lacks clear rules for sampling, is labor consuming, expensive and mainly used in combination with other indicators. AEIs enhanced improvements in N management by facilitating (i) definition of project goals, (ii) design of desired systems, (iii) evaluation of applied systems and (iv) improving effective communication. AEI applications in other countries show a similar pattern as found in The Netherlands. Limitations to AEI application relate to inconsistencies between different indicators, heterogeneity of soil characteristics and linkages of N, carbon and water management. AEIs should be applied in an integrated evaluation, at a scale that reflects the farm's spatial variability. Simple AEIs like Nitrogen Surplus should be supported by other indicators and/or model calculations. The paper concludes that AEIs proved their value in design, implementation and testing of farming systems, but they should be used with care, always keeping in mind that indicators are simplifications of complex and variable processes. 相似文献
99.
In New Zealand environmental management is essentially the responsibility of land managers. Management decisions affect both production/productivity and the environment. However, responsibility for ensuring positive environmental outcomes falls on both local (Regional) and Central Government, and both they and international agencies such as the OECD would wish to monitor and report on changes. In terms of policy, strong links have been established via Central and Regional Government to land managers. Consumers in the market place are also, increasingly, requiring responsibility for positive environmental outcomes of those who purchase and process primary products. Strong links for responsibility have been established between our international markets and processing businesses and there is a noticeable strengthening of the links from the processors to the land manager/producer. In New Zealand a range of initiatives has been developed and implemented over recent times, whereby land managers are taking increasing responsibility for accounting for the environmental outcomes of their production activities. The range covers the spectrum from voluntary to compulsory (e.g., in order to meet market requirements) and from those initiated by customers to processor and/or producer initiatives. This paper follows the evolution of the principles that drove the predominant activities of the period and the processes that initiated the changes in environmental management. As the focus of agriculturalists changed from pioneering in a new world, to establishing a production base, to economic reality, and finally to environmental responsibility, the processes of extension adapted to meet the new challenge. 相似文献
100.
Jenny Sahlin Tomas Ekvall Mattias Bisaillon Johan Sundberg 《Resources, Conservation and Recycling》2007,51(4):827-846
A tax on waste-to-energy incineration of fossil carbon in municipal solid waste from households was introduced in Sweden on July 1, 2006. The tax has led to higher incineration gate fees. One of the main purposes with the tax is to increase the incentive for recycling of materials, including biological treatment. We investigate whether and to what extent this effect can be expected. A spreadsheet model is developed in order to estimate the net marginal cost of alternative waste treatment methods, i.e., the marginal cost of alternative treatment minus avoided cost of incineration. The value of the households’ time needed for source separation is discussed and included. The model includes the nine largest fractions, totalling 85% (weight), of the household waste currently being sent to waste incineration: food waste, newsprint, paper packaging, soft and hard plastic packaging, diapers, yard waste, other paper waste, and non-combustible waste. Our results indicate that the incineration tax will have the largest effect on biological treatment of kitchen and garden waste, which may increase by 9%. The consequences of an incineration tax depend on: (a) the level of the tax, (b) whether the tax is based on an assumed average Swedish fossil carbon content or on the measured carbon content in each incineration plant, (c) institutional factors such as the cooperation between waste incinerators, and (d) technological factors such as the availability of central sorting of waste or techniques for measurement of fossil carbon in exhaust gases, etc. Information turns out to be a key factor in transferring the governing force of the tax to the households as well improving the households’ attitudes towards material recycling. 相似文献