全文获取类型
收费全文 | 982篇 |
免费 | 18篇 |
国内免费 | 7篇 |
专业分类
安全科学 | 34篇 |
废物处理 | 32篇 |
环保管理 | 173篇 |
综合类 | 114篇 |
基础理论 | 283篇 |
环境理论 | 1篇 |
污染及防治 | 253篇 |
评价与监测 | 68篇 |
社会与环境 | 43篇 |
灾害及防治 | 6篇 |
出版年
2023年 | 27篇 |
2022年 | 32篇 |
2021年 | 14篇 |
2020年 | 12篇 |
2019年 | 29篇 |
2018年 | 23篇 |
2017年 | 33篇 |
2016年 | 39篇 |
2015年 | 25篇 |
2014年 | 42篇 |
2013年 | 84篇 |
2012年 | 35篇 |
2011年 | 81篇 |
2010年 | 52篇 |
2009年 | 42篇 |
2008年 | 46篇 |
2007年 | 55篇 |
2006年 | 59篇 |
2005年 | 32篇 |
2004年 | 32篇 |
2003年 | 35篇 |
2002年 | 33篇 |
2001年 | 19篇 |
2000年 | 6篇 |
1999年 | 3篇 |
1998年 | 11篇 |
1997年 | 14篇 |
1996年 | 15篇 |
1995年 | 6篇 |
1994年 | 10篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 8篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1965年 | 1篇 |
1941年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有1007条查询结果,搜索用时 187 毫秒
591.
Greenhouse gases are more sampled than ever because of environmental interests. Gas samples are often inserted into vials with gas tight butyl rubber septa before concentration analysis. Little is known on the global transfer property of butyl rubber septa for CO2, N2O and CH4. Sorption kinetics were measured by injecting CO2, N2O or CH4 into glass vials with either one of four butyl rubber septa types and stored during 90 days. CO2 and N2O concentrations decreased during storage depending upon septa type and initial concentration, with the highest linear rate being 0.023 for CO2 and 0.0015 mg L(-3) day(-1) for N2O. When a low concentration was injected, CH4 concentration changes over time were small and did not differ between septa types. Sorption isotherms were measured using nine concentrations and stored during 45 days. CO2 sorption isotherms ranged from 0 to 3.7 x 10(-3) m(3) m(-2) and N2O from 0.3 to 1.4 x 10(-3) m(3) m(-2). Examples of errors associated with the use of these butyl rubber septa are given. 相似文献
592.
We compared naturally alkaline streams with limestone lithology to freestone streams with and without acid mine drainage (AMD) to predict benthic macroinvertebrate community recovery from AMD in limestone-treated watersheds. Surrogate-recovered (limestone) and, in many cases, freestone systems had significantly higher macroinvertebrate densities; diversity; taxa richness; Ephemeroptera, Plecoptera, and Trichoptera (EPT) taxa; EPT/chironomid ratios; scraper/collector-gatherer ratios; herbivores; collector-filterers; and scrapers. AMD-influenced systems had significantly greater numbers of Diptera and collector-gatherers. An entire trophic level (herbivores) was "restored" in surrogate-recovered streams, which also showed greater trophic specialization. Indicator analysis identified seven taxa (within Crustacea, Diptera, Nematoda, Trichoptera, and Ephemeroptera) as significant indicators of limestone systems and six taxa (within Ephemeroptera, Plecoptera, Tricoptera, Coleoptera, and Mollusca) as significant freestone indicators, all useful as biological indicators of recovery from AMD. 相似文献
593.
Accurate estimates of the extent and distribution of wetlands and streams are the foundation of wetland monitoring, management, restoration, and regulatory programs. Traditionally, these estimates have relied on comprehensive mapping. However, this approach is prohibitively resource-intensive over large areas, making it both impractical and statistically unreliable. Probabilistic (design-based) approaches to evaluating status and trends provide a more cost-effective alternative because, compared with comprehensive mapping, overall extent is inferred from mapping a statistically representative, randomly selected subset of the target area. In this type of design, the size of sample plots has a significant impact on program costs and on statistical precision and accuracy; however, no consensus exists on the appropriate plot size for remote monitoring of stream and wetland extent. This study utilized simulated sampling to assess the performance of four plot sizes (1, 4, 9, and 16 km2) for three geographic regions of California. Simulation results showed smaller plot sizes (1 and 4 km2) were most efficient for achieving desired levels of statistical accuracy and precision. However, larger plot sizes were more likely to contain rare and spatially limited wetland subtypes. Balancing these considerations led to selection of 4 km2 for the California status and trends program. 相似文献
594.
Walter D. Koenig Eric L. Walters Joseph Haydock 《Behavioral ecology and sociobiology》2009,63(11):1659-1665
In cooperatively breeding acorn woodpeckers (Melanerpes formicivorus), helper males have a large positive effect on fledging success in good acorn crop years but only a small positive effect
in poor acorn crop years, while helper females exhibit the opposite pattern. Based on these findings, we tested the “concealed
helper effects” hypothesis, which proposes that laying females reduce investment in eggs (with respect to their size, number,
or quality) in a way that confounds helper effects and results in an absence of a relationship between helpers and breeding
success. Results generally failed to support the hypothesis. Mean egg size was positively related to temperatures during the
10 days prior to egg-laying and negatively related to the food supply as indexed by the prior fall’s acorn crop, but there
were no significant differences vis-à-vis helpers except for interactions with the acorn crop that only partly corresponded
to those predicted. With respect to clutch size, females laid larger clutches when assisted by female helpers, opposite the
pattern predicted. Although our results suggest that egg size is adjusted to particular ecological circumstances, we conclude
that neither egg nor clutch size is adjusted in a way that confounds the apparent effects of helpers, as proposed by the concealed
helper effects hypothesis. 相似文献
595.
William Whipple Donald Duflois Neil Grigg Edwin Herricks Howard Holme Jonathan Jones Conrad Keyes Mike Ports Jerry Rogers Eric Strecker Scott Tucker Ben Urbonas Bud Viessman Don Vonnahme 《Journal of the American Water Resources Association》1999,35(4):713-716
ABSTRACT: The planning and developing of water resources to meet the country's needs for water supply, flood control, hydroelectric power, irrigation, and navigation now needs to take more account of environmental needs and regulations. Water resource development is often beneficial to the environment, but may also be harmful, as in cases involving salmon and various other endangered species. As a national objective, the environment must be preserved and in some cases restored; but how can this be done consistent with other national objectives, relating to life and welfare of human beings? This problem has aroused the concern of many engineers and water scientists. As a result, a national conference on this subject was held in Chicago in June 1998, as an integral part of ASCE's Annual Conference on Water Resources Planning and Management and the Annual Conference on Environmental Engineering. At the conclusion of that conference, a post-conference meeting was held by a group of prominent water resource practitioners. It was concluded at this meeting that action should be taken by our government to establish a new form of interagency approach, involving the states, as a means of coordination in cases of national importance. 相似文献
596.
597.
598.
Eric Helland 《Journal of Environmental Economics and Management》1998,35(3):242-261
The EPA suggests states inspect polluters at least once a year and use sampling and nonsampling inspections equally. States face two separate pressures in their attempts to comply with these mandates: political and budgetary. Budgetary considerations arise because inspections are costly while political pressures arise because the stringency of enforcement, in part, determines the cost abatement. This study estimates the relative importance of political and budgetary pressures in the stringency with which the Clean Water Act is enforced. The results suggest that inspections determined by budgetary concerns and the stringency of inspections is determined, in part, by political factors. 相似文献
599.
600.
Viel JF Floret N Deconinck E Focant JF De Pauw E Cahn JY 《Environment international》2011,37(2):449-453
Organochlorine chemicals may contribute to an increased risk of non-Hodgkin lymphoma (NHL) within non-occupationally exposed populations. Among these chemicals, dioxins and furans were mainly released by municipal solid waste incinerators (MSWIs) until a recent past in France, a source of exposure that is of public concern. We investigated organochlorines and the risk of NHL among neighbors of a French MSWI with high levels of dioxin emissions (Besan?on, France), using serum concentrations to assess exposure. The study area consisted of three electoral wards, containing or surrounding the MSWI. Pesticides, dioxins, furans, and polychlorinated biphenyls (PCBs) were measured in the serum of 34 newly diagnosed NHL cases (2003-2005) and 34 controls. Risks of NHL associated with each lipid-corrected serum concentration were estimated using exact logistic regression. The pesticides β-hexachlorocyclohexane (odds ratio [OR]=1.05, 95% confidence interval [CI]=1.00-1.12, per 10 ng/g lipid) and p,p' dichloro-diphenyl-trichloroethane (DDT) (OR=1.20, 95% CI=1.01-1.45, per 10 ng/g lipid) were associated with NHL risk. Evidence indicated an increased NHL risk associated with cumulative WHO(1998)-toxic equivalency factor (TEQ) concentrations (dioxins, OR=1.12, 95% CI=1.03-1.26; furans, OR=1.16, 95% CI=1.03-1.35; dioxin-like PCBs, OR=1.04, 95% CI=1.00-1.07; and total TEQ, OR=1.04, 95% CI=1.01-1.05), as well as with non dioxin-like PCBs (OR=1.02, 95% CI=1.01-1.05, per 10 ng/g lipid). Most congener-specific associations were statistically significant. This study provides strong and consistent support for an association between serum cumulative WHO(1998)-TEQ concentrations, at levels experienced by people residing in the vicinity of a polluting MSWI, and risk of NHL. 相似文献