全文获取类型
收费全文 | 2240篇 |
免费 | 174篇 |
国内免费 | 63篇 |
专业分类
安全科学 | 127篇 |
废物处理 | 17篇 |
环保管理 | 1041篇 |
综合类 | 597篇 |
基础理论 | 365篇 |
环境理论 | 2篇 |
污染及防治 | 50篇 |
评价与监测 | 57篇 |
社会与环境 | 129篇 |
灾害及防治 | 92篇 |
出版年
2023年 | 26篇 |
2022年 | 51篇 |
2021年 | 49篇 |
2020年 | 52篇 |
2019年 | 51篇 |
2018年 | 59篇 |
2017年 | 85篇 |
2016年 | 94篇 |
2015年 | 92篇 |
2014年 | 77篇 |
2013年 | 121篇 |
2012年 | 80篇 |
2011年 | 130篇 |
2010年 | 89篇 |
2009年 | 105篇 |
2008年 | 97篇 |
2007年 | 113篇 |
2006年 | 107篇 |
2005年 | 82篇 |
2004年 | 70篇 |
2003年 | 75篇 |
2002年 | 51篇 |
2001年 | 56篇 |
2000年 | 53篇 |
1999年 | 68篇 |
1998年 | 41篇 |
1997年 | 37篇 |
1996年 | 42篇 |
1995年 | 40篇 |
1994年 | 27篇 |
1993年 | 17篇 |
1992年 | 22篇 |
1991年 | 18篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 13篇 |
1987年 | 21篇 |
1986年 | 22篇 |
1985年 | 24篇 |
1984年 | 22篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1980年 | 15篇 |
1979年 | 17篇 |
1978年 | 20篇 |
1977年 | 14篇 |
1975年 | 10篇 |
1973年 | 16篇 |
1972年 | 14篇 |
1971年 | 16篇 |
排序方式: 共有2477条查询结果,搜索用时 0 毫秒
991.
David Meko Charles W. Stockton W. R. Boggess 《Journal of the American Water Resources Association》1995,31(5):789-801
ABSTRACT: Frequent and persistent droughts exacerbate the problems caused by the inherent scarcity of water in the semiarid to arid parts of the southwestern United States. The occurrence of drought is driven by climatic variability, which for years before about the beginning of the 20th century in the Southwest must be inferred from proxy records. As part of a multidisciplinary study of the potential hydrologic impact of severe sustained drought on the Colorado River, the physical basis and limitations of tree rings as indicators of severe sustained drought are reviewed, and tree-ring data are analyzed to delineate a “worst-case” drought scenario for the Upper Colorado River Basin (UCRB). Runs analysis of a 121-site tree-ring network, 1600–1962, identifies a four-year drought in the 1660s as the longest-duration large-scale drought in the Southwest in the recent tree-ring record. Longer tree-ring records suggest a much longer and more severe drought in 1579–1598. The regression estimate of the mean annual Colorado River flow for this period is 10.95 million acre-feet, or 81 percent of the long-term mean. The estimated flows for the 1500s should be used with caution in impact studies because sample size is small and some reconstructed values are extrapolations. 相似文献
992.
Gerald E. Galloway 《Journal of the American Water Resources Association》2011,47(3):563-570
Galloway, Gerald E., 2011. If Stationarity Is Dead, What Do We Do Now? Journal of the American Water Resources Association (JAWRA) 47(3):563‐570. DOI: 10.1111/j.1752‐1688.2011.00550.x Abstract: In January 2010, hydrologists, climatologists, engineers, and scientists met in Boulder, Colorado, to discuss the report of the death of hydrologic stationarity and the implications this might have on water resources planning and operations in the United States and abroad. For decades planners have relied on design guidance from the Interagency Advisory Committee on Water Data Bulletin 17B that was based upon the concept of stationarity. After 2½ days of discussion it became clear that the assembled community had yet to reach an agreement on whether or not to replace the assumption of stationarity with an assumption of nonstationarity or something else. Hydrologists were skeptical that data gathered to this point in the 21st Century point to any significant change in river parameters. Climatologists, on the other hand, point to climate change and the predicted shift away from current conditions to a more turbulent flood and drought filled future. Both groups are challenged to provide immediate guidance to those individuals in and outside the water community who today must commit funds and efforts on projects that will require the best estimates of future conditions. The workshop surfaced many approaches to dealing with these challenges. While there is good reason to support additional study of the death of stationarity, its implications, and new approaches, there is also a great need to provide those in the field the information they require now to plan, design, and operate today’s projects. 相似文献
993.
Nigel Roome 《Journal of Environmental Planning and Management》1984,27(1):12-17
The Countryside Commission's report A Better Future for the Uplands puts forward a new strategy for public intervention in the uplands of England and Wales. The aim of the report is to integrate rural policies and to promote higher environmental priorities in rural areas. This paper considers the degree to which the report is successful in planning to achieve these ends. The paper is specifically concerned with the planning methodology on which the report is based. The paper argues for an approach to rural planning which permits the consideration of more radical solutions to rural problems, along with the application of a more systematic planning methodology, in order to assist in the choice of an appropriate direction for planned change. 相似文献
994.
Donald A. Wilhite Deborah A. Wood 《Journal of the American Water Resources Association》1985,21(1):31-38
ABSTRACT: Although droughts are a frequent occurrence over much of the United States, response by state and federal government has been ineffective and poorly coordinated. Recently, several states have recognized the value of drought emergency planning and have developed plans to assist them in responding more effectively to prolonged periods of water shortage. These states have created an organizational structure to coordinate the assessment and response activities of state and federal agencies. Each state's drought response plan is unique since each state's water supply and management problems, and their consequent impacts, are unique. The drought response plans developed by Colorado, South Dakota and New York are reviewed here in detail. We recommend that other states affected by frequent and severe water shortages also develop drought emergency plans. These plans will enhance state government's ability to implement effective measures in a timely manner and, ultimately, may provide added incentive for the federal government to develop the national drought response plan called for by the General Accounting Office in 1979. 相似文献
995.
Jerry Delli Priscoli 《Journal of the American Water Resources Association》1977,13(5):953-958
ABSTRACT: While federal water resources laws and regulations require social analysis, no one workable formula exists for integrating it into water resources planning. Two primary problems in integrating social analysis into planning are examined; making trade-offs between policy acceptability and theoretical competence, and managing social analysis in planning. For illustration, the article builds on emerging trends within the U.S. Army Corps of Engineers. It concludes by observing that creative application of social theory to policy problems along with innovative data gathering techniques are the primary routes to managing these problems. 相似文献
996.
Frank Dobrowolski Leonard Grillo 《Journal of the American Water Resources Association》1977,13(3):455-460
ABSTRACT: The current 201 study by the Bergen County Sewer Authority illustrates possibilities for improving the currently defined relationships between 201, 208 and 303 studies. The Bergen County Sewer Authority serves 115 square miles in northeast New Jersey, providing sewerage service to 507,000 people in 43 municipalities. Its STP discharges to the Hackensack River, a tidal estuary recently classified as Water Quality Limited, and which receives significant non-plant loading. The subject 201 study is concurrent with 208 and 303 planning by NJDEP. Preliminary evaluations show that detailed 201 work can affect the conclusions of 303 and 208 studies, and that a wider (environmental - social as well as economic) interpretation of cost-effectiveness can demand re-examination of prior assumptions and decisions, a task not typically part of 208–303 work. Increased flexibility is needed in applying 303 and 208 recommendations to defining 201 studies and NPDES permit criteria, particularly in analysis of water use objectives, water quality parameters and future flows, loadings and facility costs. Further, perception of alternatives can be clarified by broadening analysis of costs and control and plant strategies. Inclusion of 201 planning at all stages of regional planning can synergistically improve the total planning process. 相似文献
997.
Use of agricultural land evaluation and site assessment in Whitman County,Washington, USA 总被引:2,自引:0,他引:2
Melanie Tyler Liese Hunter Frederick Steiner Dennis Roe 《Environmental management》1987,11(3):407-412
Whitman County, Washington, USA, one of the largest wheat producing counties in the country, developed a land evaluation and site assessment system for evaluating proposed conversions of agricultural land to heavy commercial uses. The system uses soil potential indices to determine a land evaluation score and a nine-factor site assessment system to weigh suitability for development. Details on each of these are provided along with results for four sample sites.Scientific Paper no. 7165, College of Argiculture and Home Economics Research Paper, Washington State University, Pullman, Washington, project no. 0010. 相似文献
998.
Richard Hill‐Rowley Thomas McClain Matthew Malone 《Journal of the American Water Resources Association》2003,39(1):99-111
ABSTRACT: This paper presents a methodology for preparing a static water level map using a sample of water level measurements obtained from the well log records of private wells that are finished in glacial drift. The test was conducted in Tyrone Township, located in east central Michigan. A variety of selection criteria were examined and the resulting maps were compared with a ground truth map that was prepared from water level measurements obtained in the field. The map prepared from a random sample of wells at a density of two points per section best approximates the ground truth map. Using a sample of records from the Michigan Statewide Groundwater Database to create static water levels that are used in community ground water vulnerability analyses will provide a more accurate map than using the complete dataset or other selection criteria based on temporal groupings or seasonality. 相似文献
999.
Thomas E. Croley Carol L. Luukkonen 《Journal of the American Water Resources Association》2003,39(1):149-163
ABSTRACT: Computer simulations involving general circulation models, a hydrologic modeling system, and a ground water flow model indicate potential impacts of selected climate change projections on ground water levels in the Lansing, Michigan, area. General circulation models developed by the Canadian Climate Centre and the Hadley Centre generated meteorology estimates for 1961 through 1990 (as a reference condition) and for the 20 years centered on 2030 (as a changed climate condition). Using these meteorology estimates, the Great Lakes Environmental Research Laboratory's hydrologic modeling system produced corresponding period streamflow simulations. Ground water recharge was estimated from the streamflow simulations and from variables derived from the general circulation models. The U.S. Geological Survey developed a numerical ground water flow model of the Saginaw and glacial aquifers in the Tri‐County region surrounding Lansing, Michigan. Model simulations, using the ground water recharge estimates, indicate changes in ground water levels. Within the Lansing area, simulated ground water levels in the Saginaw aquifer declined under the Canadian predictions and increased under the Hadley. 相似文献
1000.
Bryan Boulanger Nikolaos P. Nikolaidis 《Journal of the American Water Resources Association》2003,39(2):325-336
ABSTRACT: Abundant use of copper based products has resulted in increased violation of copper water quality criteria in runoff from urban storm water systems. The objectives of this work were to understand the mobility and toxicity of copper in an urban watershed and to apportion the amount of copper entering the freshwater receiving stream from different urban land covers using a mass balance approach. Sixteen rainfall events collected from the University of Connecticut study watershed between August 1998 and September 2000 were analyzed to assess copper flux in an urban storm water system. Mean flow weighted dissolved copper concentrations observed in the study for copper based architectural material runoff, pervious area runoff, impervious area runoff, and in the receiving stream were 1210 ± 840, 9 ± 3, 8 ± 2, and 14 ± 7 μg/L, respectively. Mean dissolved copper concentrations in the receiving stream exceeded Connecticut's water quality criteria. Despite exceeding the dissolved concentration based criteria, cupric ion concentrations at the system outlet remained below 0.05 μg/L for all storms analyzed, and no acute toxicity (using Daphnia pulex as the test organism) was measured in samples collected from the stream. 相似文献