全文获取类型
收费全文 | 877篇 |
免费 | 10篇 |
国内免费 | 15篇 |
专业分类
安全科学 | 51篇 |
废物处理 | 20篇 |
环保管理 | 125篇 |
综合类 | 140篇 |
基础理论 | 220篇 |
环境理论 | 1篇 |
污染及防治 | 223篇 |
评价与监测 | 79篇 |
社会与环境 | 35篇 |
灾害及防治 | 8篇 |
出版年
2023年 | 7篇 |
2022年 | 4篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 11篇 |
2018年 | 17篇 |
2017年 | 14篇 |
2016年 | 18篇 |
2015年 | 24篇 |
2014年 | 15篇 |
2013年 | 99篇 |
2012年 | 35篇 |
2011年 | 59篇 |
2010年 | 42篇 |
2009年 | 44篇 |
2008年 | 54篇 |
2007年 | 45篇 |
2006年 | 34篇 |
2005年 | 30篇 |
2004年 | 27篇 |
2003年 | 26篇 |
2002年 | 33篇 |
2001年 | 16篇 |
2000年 | 17篇 |
1999年 | 6篇 |
1998年 | 13篇 |
1997年 | 8篇 |
1996年 | 13篇 |
1995年 | 8篇 |
1994年 | 11篇 |
1993年 | 7篇 |
1992年 | 11篇 |
1991年 | 13篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1971年 | 4篇 |
1969年 | 4篇 |
1960年 | 4篇 |
1956年 | 3篇 |
排序方式: 共有902条查询结果,搜索用时 15 毫秒
251.
Tedesco M Bohlen WF Howard-Strobel MM Cohen DR Tebeau PA 《Environmental monitoring and assessment》2003,81(1-3):35-42
A network of five water quality monitoring stations has been established in Long Island Sound, measuring temperature, salinity, and dissolved oxygen since 1999. The stations are located in areas of extreme water quality degradation (western Long Island Sound) as well as in pristine areas (eastern Long Island Sound). The data from these stations are collected every 15 minutes and posted to the project web site in real time as provisional data. After subsequent quality assurance procedures, the data are archived to the project File Transfer Protocol (FSP) site for downloading by the user community. The network of stations is in part supported logistically by a number of partners, including state and local agencies, schools, and non-governmental organizations. Data from the monitoring programs of some of these partners are also published to the project website providing a more comprehensive and complete picture of the status of the Sound than can be provided independently. This repository of information is used by marine educators, resource managers, scientists, and the general public, each with a different end purpose. We use the data from two of the stations to show that these high frequency time series measurements can be used to complement and enhance other monitoring programs within the Sound, documenting in greater detail the occurrence and duration of hypoxic events. 相似文献
252.
Frank A. Vertucci 《Environmental monitoring and assessment》1989,12(1):59-59
Wilderness lakes in the U.S. are at risk to the effects of atmospheric pollution. The results of the EPA Western Lake Survey, for example, show that many of the lakes in the West have very low concentrations of dissolved constituents, and are sensitive to acidification. Lakes located in wilderness areas were found to be particularly sensitive: median ANC values of 91.4 eq/1 compared to 282.7 eq/1 in non-wilderness areas. Sampling remote wilderness lakes is difficult and expensive. For example, the cost of sampling each lake in the National surface water survey was about $ 4000 per lake. Remote sensing methods may provide an alternative means of monitoring the chemistry of wilderness lakes. This study defines the feasibility of the remote monitoring of lake chemistry in the Adirondack Park region of New York by comparing measured lake chemistry with field reflectance measurements, remote reflectance measurements from aircraft and satellite and laboratory and airborne laser fluorosensor data.Water samples collected from a representative population of Adirondack Park lakes were analyzed for pH, acid neutralizing capacity (ANC), dissolved organic carbon (DOC), total reactive aluminum and plant pigment concentration concurrent with the collection of remote sensing data. Lake parameters estimated from field reflectance measurements which directly effect lake optical properties, total pigments, DOC, and turbidity were estimated with less error and more precision than those parameters not directly related to lake optics, pH, ANC and A1 concentration. Results from airborne MSS and Landsat MSS data produced lower R2 values than estimates using field reflectance.The concentration of DOC can be estimated remotely by using laser fluorosensing. The spectral-fluorescence properties of DOC were correlated with the pH and aluminum concentrations in the lake water. Remotely measurable DOC fluorescence spectra were used to estimate DOC, H, and A1 concentrations.Of the methods investigated, laser fluorosensing shows the most promise for the remote prediction of lake DOC, hydrogen ion and aluminum concentration in Adirondack lakes while reflectance measures may be used to estimate lake chlorophyll, DOC and transparency. Given the large number of wilderness lakes and the difficulty of sampling in remote wilderness, remote sensing methods may provide an alternative, while less precise, method of monitoring lake chemistry. The applicability of these findings to lakes in other wilderness areas is unknown. Similar studies of the feasibility of monitoring Western wilderness lake chemistry with remote sensing methods are being initiated.Supported by an A. W. Mellon Foundation Grant to Dr. G. E. Likens while a student in the Section of Ecology and Systematics, Cornell University, Ithaca, NY and a Fellow of the Institute for Ecosystem Studies, New York Botanical Garden, Mary Flagler Cary Arboretum, Millbrook, NY.Contribution from Fourth World Wilderness Congress-Acid Rain Symposium, Denver (Estes Park), Colorado, September 11–18, 1987. 相似文献
253.
R. Frank K. I. Stonefield H. Luyken P. Suda 《Environmental monitoring and assessment》1986,6(3):259-265
Kidney and muscle samples were collected from 197 bovine and 33 porcine carcasses and liver and muscle from 115 poultry carcasses across the province. These tissues were analyzed for the following 13 elements, Ag, As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Sb, Se, and Zn. The intent of the study was to determine normal background levels. Tissue concentration of these elements fell into five orders of magnitude ranging from < 10 g kg–1 for Ag to over 10 mg kg–1 for Zn. Similar concentrations were observed in the three specie tissues being compared except for higher concentrations of Cd and Sb in bovine kidneys. In avian tissues Mo contents were higher in liver than muscle. When samples from all three species were grouped by age, no distinct trends were observed to indicate an increase in metal contents with age, with the exception of Cd in bovine kidneys. 相似文献
254.
W. C. Schutte R. S. Cole K. R. Long C. W. Frank 《Environmental monitoring and assessment》1982,1(3):257-261
Twenty seven UFFI homes in Colorado and Wisconsin were sampled for formaldehyde levels. The formaldehyde concentrations found in these homes averaged 0.059 ppm. Two homes were monitored for an extended period to determine the impact of ambient climatic conditions. 相似文献
255.
James C. McFarlane Amy Cross Clyde Frank Robert D. Rogers 《Environmental monitoring and assessment》1981,1(1):75-81
Gaseous benzene was rapidly depleted in exposure chambers containing viable soils and plants. When separate components of the system were analyzed, no benzene was detected in soils, plants, or water. Soil microorganisms were shown to be responsible for metabolizing benzene, yielding CO2 as the main product. The rates were sufficiently rapid to suggest that this reaction forms a major pathway for the elimination of benzene from the environment.This work was sponsored and conducted at the Environmental Protection Agency-Environmental Monitoring Systems Laboratory, Las Vegas, Nevada, U.S.A. 相似文献
256.
Bignert A Riget F Braune B Outridge P Wilson S 《Journal of environmental monitoring : JEM》2004,6(4):351-355
The goal of this paper is to describe and discuss statistical power with respect to mercury in Arctic biota, using data gathered during the past two or three decades, mostly under the auspices of AMAP Phases I and II. It will describe the current levels of power of existing data sets to detect temporal trends of Hg concentrations. If the desired power is fixed to an appropriate magnitude, the minimum size of a detectable trend within a specified time period or the number of years that is required to detect a certain trend could be estimated provided that the random between-year variation for the current time-series is known. These various measures of performance of the AMAP mercury time-series, derived from the power analysis, are discussed in some detail. The number of years required to detect a certain trend at a particular power at a specific Type I error rate (alpha) is compared with the actual number of years available when the AMAP Phase II assessment was carried out. In general the investigated time-series were too short to possess an acceptable statistical power. The effect of varying the Type-I error rate, the slope of a trend and the desired power is investigated to rank the importance of the various components regulating the statistical power. The consequence of sampling less frequently than once a year is considerable loss of power. 相似文献
257.
We propose a biodiversity credit system for trading endangered species habitat designed to minimize and reverse the negative
effects of habitat loss and fragmentation, the leading cause of species endangerment in the United States. Given the increasing
demand for land, approaches that explicitly balance economic goals against conservation goals are required. The Endangered
Species Act balances these conflicts based on the cost to replace habitat. Conservation banking is a means to manage this
balance, and we argue for its use to mitigate the effects of habitat fragmentation. Mitigating the effects of land development
on biodiversity requires decisions that recognize regional ecological effects resulting from local economic decisions. We
propose Landscape Equivalency Analysis (LEA), a landscape-scale approach similar to HEA, as an accounting system to calculate
conservation banking credits so that habitat trades do not exacerbate regional ecological effects of local decisions. Credits
purchased by public agencies or NGOs for purposes other than mitigating a take create a net investment in natural capital
leading to habitat defragmentation. Credits calculated by LEA use metapopulation genetic theory to estimate sustainability
criteria against which all trades are judged. The approach is rooted in well-accepted ecological, evolutionary, and economic
theory, which helps compensate for the degree of uncertainty regarding the effects of habitat loss and fragmentation on endangered
species. LEA requires application of greater scientific rigor than typically applied to endangered species management on private
lands but provides an objective, conceptually sound basis for achieving the often conflicting goals of economic efficiency
and long-term ecological sustainability. 相似文献
258.
An assessment of household willingness to pay for curbside recycling: a comparison of payment card and referendum approaches 总被引:8,自引:0,他引:8
Curbside recycling is a tool that communities use to reduce the need for landfill space. This study provides contingent valuation estimates of household willingness to pay (WTP) to continue a curbside recycling program in the face of budget cuts. Comparisons of two forms of the contingent valuation method (CVM) are provided: a single bounded referendum and a payment card. Neither approach emerges as unambiguously superior. Response rates were virtually identical. Both approaches show that support for curbside recycling is highly sensitive to price. Regression results from the payment card provided a more thorough identification of socio-demographic variables associated with WTP than the referendum, but the explanatory power of the two regressions did not differ significantly. The referendum estimates of mean WTP exceed those from the payment card, although the disparities are less than those typically reported in the CVM literature. Local policy makers cited the CVM results as influencing their decisions regarding funding options for the future of the program, and seemed to appreciate the fact that the two approaches provided a fairly narrow range of estimates of WTP. In an era when more of the burden of financing of environmental programs is being shifted to the local level, use of CVM to estimate the WTP of consumers for highly disaggregated goods and services designed to achieve environmental improvement will likely become more relevant to local decision makers who are interested in understanding their constituents' views. 相似文献
259.
260.
John Cosgrove Frank Doyle John Littlewood Paul Wilgeroth 《International Journal of Sustainable Engineering》2017,10(4-5):233-240
AbstractEnergy management in small to medium enterprises (SMEs) remains undeveloped due to competing priorities and a lack of specialist knowledge. However considerable savings can be demonstrated where companies take the time to investigate their energy use. Savings of over 20% can be achieved through changes to operational and behavioural practice. Additional benefits, such as improved production tracking and improved maintenance, can been seen which add to the value in undertaking an energy monitoring and targeting (M&T) plan. The method described involves the application of a series of ‘virtuous’ cycles of engagement and energy savings that can be applied from the highest factory level right down to a specific machine. The analysis of overall energy use from utility bills and the visualisation of typical machine power profiles aid in understanding the drivers of energy consumption and in engaging management in energy efficiency. The monitoring of specific machines in production highlights the significant consumption of electricity during non-productive times. The development of energy performance indicators is described for product variations which can be useful in tendering for business and selecting optimum production pathways. The approach is illustrated with data from a case study of a precision engineering SME based in Limerick, Ireland. 相似文献