全文获取类型
收费全文 | 4033篇 |
免费 | 100篇 |
国内免费 | 53篇 |
专业分类
安全科学 | 250篇 |
废物处理 | 153篇 |
环保管理 | 831篇 |
综合类 | 468篇 |
基础理论 | 1006篇 |
环境理论 | 3篇 |
污染及防治 | 956篇 |
评价与监测 | 312篇 |
社会与环境 | 166篇 |
灾害及防治 | 41篇 |
出版年
2023年 | 31篇 |
2022年 | 41篇 |
2021年 | 46篇 |
2020年 | 57篇 |
2019年 | 70篇 |
2018年 | 85篇 |
2017年 | 123篇 |
2016年 | 140篇 |
2015年 | 109篇 |
2014年 | 134篇 |
2013年 | 351篇 |
2012年 | 185篇 |
2011年 | 236篇 |
2010年 | 182篇 |
2009年 | 203篇 |
2008年 | 210篇 |
2007年 | 221篇 |
2006年 | 205篇 |
2005年 | 178篇 |
2004年 | 156篇 |
2003年 | 138篇 |
2002年 | 136篇 |
2001年 | 97篇 |
2000年 | 69篇 |
1999年 | 63篇 |
1998年 | 48篇 |
1997年 | 64篇 |
1996年 | 50篇 |
1995年 | 54篇 |
1994年 | 56篇 |
1993年 | 46篇 |
1992年 | 39篇 |
1991年 | 31篇 |
1990年 | 29篇 |
1989年 | 27篇 |
1988年 | 23篇 |
1987年 | 17篇 |
1986年 | 17篇 |
1985年 | 23篇 |
1984年 | 18篇 |
1983年 | 28篇 |
1982年 | 22篇 |
1981年 | 32篇 |
1980年 | 19篇 |
1979年 | 18篇 |
1978年 | 13篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1969年 | 4篇 |
排序方式: 共有4186条查询结果,搜索用时 15 毫秒
81.
Chester W. Spicer Michael W. Holdren Kenneth A. Cowen Darrell W. Joseph Jan Satola Bradley Goodwin Howard Mayfield Alexander Laskin M. Lizabeth Alexander John V. Ortega Matthew Newburn Robert Kagann Ram Hashmonay 《Atmospheric environment (Oxford, England : 1994)》2009,43(16):2612-2622
Aircraft emissions affect air quality on scales from local to global. More than 20% of the jet fuel used in the U.S. is consumed by military aircraft, and emissions from this source are facing increasingly stringent environmental regulations, so improved methods for quickly and accurately determining emissions from existing and new engines are needed. This paper reports results of a study to advance the methods used for detailed characterization of military aircraft emissions, and provides emission factors for two aircraft: the F-15 fighter and the C-130 cargo plane. The measurements involved outdoor ground-level sampling downstream behind operational military aircraft. This permits rapid change-out of the aircraft so that engines can be tested quickly on operational aircraft. Measurements were made at throttle settings from idle to afterburner using a simple extractive probe in the dilute exhaust. Emission factors determined using this approach agree very well with those from the traditional method of extractive sampling at the exhaust exit. Emission factors are reported for CO2, CO, NO, NOx, and more than 60 hazardous and/or reactive organic gases. Particle size, mass and composition also were measured and are being reported separately. Comparison of the emissions of nine hazardous air pollutants from these two engines with emissions from nine other aircraft engines is discussed. 相似文献
82.
Cora J. Young Michael D. Hurley Timothy J. Wallington Scott A. Mabury 《Atmospheric environment (Oxford, England : 1994)》2009,43(24):3717-3724
Relative rate techniques were used to determine k(Cl + CF3CFCFCF3) = (7.27 ± 0.88) × 10?12, k(Cl + CF3CF2CFCF2) = (1.79 ± 0.41) × 10?11, k(OH + CF3CFCFCF3) = (4.82 ± 1.15) × 10?13, and k(OH + CF3CF2CFCF2) = (1.94 ± 0.27) × 10?12 cm3 molecule?1 s?1 in 700 Torr of air or N2 diluent at 296 K. The chlorine atom- and OH radical-initiated oxidation of CF3CFCFCF3 in 700 Torr of air gives CF3C(O)F in molar yields of 196 ± 11 and 218 ± 20%, respectively. Chlorine atom-initiated oxidation of CF3CF2CFCF2 gives molar yields of 97 ± 9% CF3CF2C(O)F and 97 ± 9% COF2. OH radical-initiated oxidation of CF3CF2CFCF2 gives molar yields of 110 ± 15% CF3CF2C(O)F and 99 ± 8% COF2. The atmospheric fate of CF3CF2C(O)F and CF3C(O)F is hydrolysis to give CF3CF2C(O)OH and CF3C(O)OH. The atmospheric lifetimes of CF3CFCFCF3 and CF3CF2CFCF2 are determined by reaction with OH radicals and are approximately 24 and 6 days, respectively. The contribution of CF3CFCFCF3 and CF3CF2CFCF2 to radiative forcing of climate change will be negligible. 相似文献
83.
Zhao Ma Dennis R. Becker Michael A. Kilgore 《Journal of Environmental Planning and Management》2009,52(8):1035-1051
Following the intent of the National Environmental Policy Act of 1969, many states have adopted policies and procedures directing state agencies and local government units to evaluate the potential environmental impacts of development projects prior to their undertaking. In contrast to a rich literature on federal requirements, current understanding of state environmental review is narrowly focused and outdated. This paper seeks to provide information on the landscape of state environmental review policy frameworks. The paper identifies 37 states with formal environmental review requirements through a document review of state statutes, administrative rules and agency-prepared materials, and confirms this finding through a survey of state administrators. A two-tier classification is used to distinguish states based on the approach taken to address environmental review needs and the scope and depth of relevant policies and procedures implemented. This paper also provides a discussion of policy and programme attributes that may contribute to effective practice, and of the potential for adopting relevant legislation in states where environmental review is currently lacking. 相似文献
84.
Michael D. Kaplowitz Felix K. Yeboah Laurie Thorp Aimee M. Wilson 《Resources, Conservation and Recycling》2009,53(11):612-623
With increasing environmental challenges confronting our planet, colleges and universities are trying different approaches for minimizing their adverse environmental impacts. Among the approaches being used to revitalize campus sustainability efforts, new waste management strategies have included attempts to improve campus-recycling programs. This paper presents select findings from a comprehensive study at a large, Tier I university aimed at, among other things, informing university administration and decision makers working on the planning and implementation of a new campus-wide recycling facility and program. The researchers used a mixed-method approach to help them develop an understanding of the campus community's (1) perceived barriers to recycling, (2) recycling knowledge, (3) program preferences, and (4) environmental attitudes. The results from a web-based survey (n = 3896, RR1 = 24.9%) suggest, communication efforts for recycling programming should focus more on messages concerning what, how, and where to recycle rather than messages on why to recycle. Furthermore, the results suggest recycling-related publicity approaches should differentiate their mode and content for different segments of the community. 相似文献
85.
An indispensable asset at risk: merits and needs of chemicals-related environmental sciences 总被引:1,自引:1,他引:0
86.
A method for quality screening is suggested to detect volatile impurities in inorganic coagulants that are used for drinking water treatment. Static headspace gas chromatography with mass spectrometry detection (HS–GCMS) is sensitive and selective to detect volatiles in low concentrations. This study has discovered that volatile organic impurities are detectable in ferric and aluminium-based coagulants which are used for drinking water treatment. For ferric chloride, 2-propanol was detected at a level of 17–24 μg ml−1, acetone at 0.7–1.7 μg ml−1, 1,1,1-trichloroacetone at 0.02–0.04 μg ml−1, trichloromethane at 0.01–0.02 μg ml−1 and toluene at 0.01–0.12 μg ml−1. For ferric chloride sulfate, acetone was detected at a level of 0.12 μg ml−1, 1,1,1-trichloroacetone at 0.06–0.08 μg ml−1, trichloromethane at 0.13–0.23 μg ml−1, bromodichloromethane at 0.04–0.06 μg ml−1 and dibromochloromethane at 0.04–0.05 μg ml−1. For aluminium hydroxide chloride, only trichloromethane was detectable, but below the method detection limits (MDL). Although the concentrations of these impurities in commercial coagulants are low, this observation is important and should have impact on water industries for them to pay attention to the chemicals they are using for drinking water production. 相似文献
87.
Michael W. Suplee Vicki Watson Mark Teply Heather McKee 《Journal of the American Water Resources Association》2009,45(1):123-140
Abstract: A public opinion survey was carried out in Montana to ascertain if the public identifies a level of benthic (bottom‐attached) river and stream algae that is undesirable for recreation. The survey had two parts; an On‐River survey and a By‐Mail survey. The On‐River survey was conducted via 44 trips randomly scheduled throughout the state during which recreators were interviewed in‐person at the stream. Selection of stream segments and survey dates/times was based on known, statewide recreational use patterns. By‐Mail survey forms were sent to 2,000 individuals randomly selected from Montana’s Centralized Voter File (CVF) available from the Montana Secretary of State. The CVF was current through 2004 and represented over 85% of the state’s eligible voting population. In both surveys, eight randomly ordered photographs depicting varying levels of stream benthic algae were presented, and participants were asked if the algae level shown was desirable or undesirable for recreation. Survey form design, selection of photographs, and pretesting followed acceptable protocols that limited unintentional bias through survey execution. There were 433 returned forms (389 complete) for the By‐Mail survey, while the On‐River survey documented 563 interviews. In both surveys, as benthic algal chlorophyll a (Chl a) levels increased, desirability for recreation decreased. (Other measures of benthic algae biomass are presented as well.) For the public majority, mean benthic Chl a levels ≥200 mg/m2 were determined to be undesirable for recreation, whereas mean levels ≤150 mg Chl a/m2 were found to be desirable. Error rates were within the survey’s statistical design criteria (≤5%). The largest potential error source was nonresponse in the By‐Mail survey; however, the population represented by nonrespondents would have to exhibit profoundly different perceptions of river and stream algae to meaningfully alter the results. Results support earlier work in the literature suggesting 150 mg Chl a/m2 represents a benthic algae nuisance threshold. 相似文献
88.
Michael J. White Daniel E. Storm Michael D. Smolen Hailin Zhang 《Journal of the American Water Resources Association》2009,45(2):397-406
Abstract: Assessment tools to evaluate phosphorus loss from agricultural lands allow conservation planners to evaluate the impact of management decisions on water quality. Available tools to predict phosphorus loss from agricultural fields are either: (1) qualitative indices with limited applicability to address offsite water quality standards, or (2) models which are prohibitively complex for application by most conservation planners. The purpose of this research was to develop a simple interface for a comprehensive hydrologic/water quality model to allow its usage by farmers and conservation planners. The Pasture Phosphorus Management (PPM) Calculator was developed to predict average annual phosphorus (P) losses from pastures under a variety of field conditions and management options. PPM Calculator is a vastly simplified interface for the Soil and Water Assessment Tool (SWAT) model that requires no knowledge of SWAT by the user. PPM Calculator was validated using 33 months of data on four pasture fields in northwestern Arkansas. This tool has been extensively applied in the Lake Eucha/Spavinaw Basin in northeastern Oklahoma and northwestern Arkansas. PPM Calculator allows conservation planners to take advantage of the predictive capacity of a comprehensive hydrologic water quality model typically reserved for use by hydrologists and engineers. This research demonstrates the applicability of existing water quality models in the development of user friendly P management tools. 相似文献
89.
The dispersion of pollutants from naturally ventilated underground parking garages has been studied in a boundary layer wind tunnel. Two idealized model setups have been analysed, one was simulating pollutant dispersion around an isolated rectangular building and one was representing dispersion in a finite array of idealized building blocks. Flow and dispersion close to modelled ground level emission sources was measured. The results illustrate the complexity of the flow around buildings and provide insight in pollutant transport from ground level sources located directly on building surfaces. As a result, areas critical with respect to high pollutant concentrations could be visualized. Particularly, the results show high concentration gradients on the surface of the buildings equipped with modelled emission sources. Inside the boundary layers on the building walls, a significant amount of pollutants is transported to upwind locations on the surface of the building. The paper documents the potential of physical modelling to be used for the simulation and measurement of dispersion close to emission sources and within complex building arrangements. 相似文献
90.