全文获取类型
收费全文 | 4556篇 |
免费 | 46篇 |
国内免费 | 90篇 |
专业分类
安全科学 | 105篇 |
废物处理 | 162篇 |
环保管理 | 580篇 |
综合类 | 1070篇 |
基础理论 | 1025篇 |
环境理论 | 5篇 |
污染及防治 | 1032篇 |
评价与监测 | 323篇 |
社会与环境 | 376篇 |
灾害及防治 | 14篇 |
出版年
2023年 | 28篇 |
2022年 | 40篇 |
2021年 | 80篇 |
2020年 | 42篇 |
2019年 | 53篇 |
2018年 | 84篇 |
2017年 | 77篇 |
2016年 | 124篇 |
2015年 | 84篇 |
2014年 | 143篇 |
2013年 | 352篇 |
2012年 | 141篇 |
2011年 | 221篇 |
2010年 | 153篇 |
2009年 | 187篇 |
2008年 | 193篇 |
2007年 | 200篇 |
2006年 | 159篇 |
2005年 | 131篇 |
2004年 | 128篇 |
2003年 | 144篇 |
2002年 | 136篇 |
2001年 | 138篇 |
2000年 | 102篇 |
1999年 | 64篇 |
1998年 | 35篇 |
1997年 | 52篇 |
1996年 | 40篇 |
1995年 | 62篇 |
1994年 | 37篇 |
1993年 | 42篇 |
1992年 | 47篇 |
1991年 | 41篇 |
1990年 | 51篇 |
1989年 | 42篇 |
1988年 | 28篇 |
1987年 | 34篇 |
1985年 | 34篇 |
1984年 | 27篇 |
1983年 | 38篇 |
1982年 | 28篇 |
1981年 | 43篇 |
1980年 | 30篇 |
1979年 | 31篇 |
1978年 | 24篇 |
1977年 | 25篇 |
1976年 | 28篇 |
1975年 | 26篇 |
1970年 | 23篇 |
1965年 | 23篇 |
排序方式: 共有4692条查询结果,搜索用时 31 毫秒
61.
Anthropogenic effects such as contamination affect the genetic structure of populations. This study examined the temporal and geographical patterns of genetic diversity among populations of the benthic crustacean amphipod Melita plumulosa in the Parramatta River (Sydney, Australia), following an industrial chemical spill. The spill of an acrylate/methacrylate co-polymer in naphtha solvent occurred in July 2006. M. plumulosa were sampled temporally between December 2006 and November 2009 and spatially in November 2009. Genetic variation was examined at the mitochondrial cytochrome c oxidase subunit I locus. Notably, nucleotide diversity was low and Tajima’s D was significantly negative amongst amphipods collected immediately downstream from the spill for 10 months. We hypothesize that the spill had a significant localized effect on the genetic diversity of M. plumulosa. Alternate explanations include an alternate and unknown toxicant or a localized sampling bias. Future proposed studies will dissect these alternatives. 相似文献
62.
63.
Gabriel N. de O. Teixeira Arthur M. S. da Cruz Gisella R. L. Samanamud Alexandre B. França Luzia L. R. Naves Diego Melo 《Journal of environmental science and health. Part. B》2020,55(1):19-29
AbstractThe main objective of this study is the degradation of a synthetic solution of atrazine by a modified vermiculite catalyzed ozonation, in a rotating packed bed (RPB) reactor. A 0.5?L RPB reactor was used to perform the experiments, using a Central Composite Design (CCD) response surface to construct the quadratic model based on the factors: pH, catalyst concentration and reactor rotation frequency. The response variable was the removal of the organic load measured in terms of Chemical Oxygen Demand (COD). After the complete quadratic model was constructed through the response surface, the COD degradation process had an optimal removal of 41% under the following conditions: pH 8.0, rotation of 1150?rpm and catalyst concentration 0.66?g L?1. 相似文献
64.
Temporal variation of RNA: weight, RNA: protein, RNA: DNA, and protein: DNA ratios in Stenonema femoratum (Say) was assessed by monitoring at the same site in a small midwestern stream over a two-year period. Variation components were estimated using a two-way mixed model analysis of variance with weight class and collection date as main effects. About 30% of the variation in RNA concentration was within-cell variation associated with differences among individuals and analytical error. Temporal variation accounted for about 50% of the total variability in RNA concentration data. RNA: weight had 11% and RNA: protein had 17% variation attributed to weight class effects indicating that these ratios were dependent on the size of the mayfly. RNA: DNA ratios were not influenced by mayfly weight, suggesting that this ratio would be the most appropriate for comparing populations based on means of mixed individual sizes. Comparison of mean RNA: DNA ratios among collection dates yielded significant increases in the ratio during late fall in two consecutive years. Spatial variations in RNA: DNA ratios of S. femoratum collected from sites of similar habitats were not significantly different. These data encourage the future development of RNA concentration as an in situ biochemical indicator of growth rate and possibly of stress related effects on growth rate. 相似文献
65.
In this study, the composition of vinasse was first analysed. It was found to contain 8.43% dry matter, 3.3% total ash, 4% crude protein and 0.95% total carbohydrates; BOD load was determined as 63 g litre(-1). Subsequently, the effects of vinasse in various concentrations (1, 2.5, 5, 10, 25, 50, 75 and 100%) on the activity of cellulase and pectin methyl esterase and the chlorophyll and protein contents of Pisum sativum and Helianthus annuus were investigated. The activity of these enzymes and the protein and chlorophyll contents in potted plants showed a gradual increase from the control up to 2.5% concentration of vinasse, but decreased at higher concentrations. These different effects of the effluent may be due to the high BOD load and the presence of cell wall cations in it. 相似文献
66.
The catalytic effects of copper and iron compounds were examined for their behavior in promoting formation of chlorine (Cl2), the major chlorinating agent of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), in an environment simulating that of municipal waste fly ash. Formation of Cl2 occurred as a result of a metal-catalyzed reaction of HCl with O2. Catalytic activity was greatest at a temperature of approximately 400 °C, supporting a theory of de novo synthesis of PCDDs and PCDFs on fly ash particles downstream of waste combustion. 相似文献
67.
Viskari EL Rekilä R Roy S Lehto O Ruuskanen J Kärenlampi L 《Environmental pollution (Barking, Essex : 1987)》1997,97(1-2):153-160
Vertical snow sampling and moss bag transplants were used to estimate the local inorganic and organic pollutant load deposited from traffic along a major highway in Finland. The pH and concentrations of Cl(-), NO(3)(-), SO(4)(2-), Ca(2+), Na(+) and polyaromatic hydrocarbons (PAHs) were determined from snow samples collected in winter at different sites along the highway. In summer, moss bags containing 20 g of fresh red-stemmed feather moss (Pleurozium schreberi) were transplanted at the same sites. The moss bag transplants remained exposed to roadside traffic for a period of one month following which the samples were collected and the PAH profiles and concentrations were analysed. The deposition of inorganic and organic pollutants from road traffic was observed up to 60 m from the road. The prevailing winds had a significant effect on the dispersion of pollutants. Snow appears to be a good collector of inorganic pollutants from the atmosphere and can be used to monitor local airborne pollution from road traffic. Snow packs can also be used as passive collectors of organic pollutant loads from road traffic on a local scale. To monitor organic PAH deposition from the road traffic, moss bags appeared to be better indicators compared to snow sampling. The efficiency of moss bags in accumulating PAH compounds indicate that vegetation may be an important sink for traffic pollution. 相似文献
68.
Accidental releases of waste water from the first Czechoslovak nuclear power plant, A1, caused contamination of sediments of the Dudváh river, flowing into the Vah river, in Slovakia. Rather high concentrations of 137Cs and 90Sr (2150Bq dm−3 and 215Bq dm−3, respectively) were found in bottom sediments of a former channel of the re-engineered river body at a distance of about 250 m from a village, Siladice, with water-supply wells. In order to assess the possibility of contamination of the wells, underground migration of both radionuclides from the contaminated area was simulated using an original layered convection-diffusion model. Kd values determined in laboratory experiments were used. The analysis of the hydrological situation in the area reveals that the critical condition is a dominant horizontal groundwater flow near the water table in the direction from the Váh bank to Siladice, in the periods when the contaminated body lies under the water table. The simulation calculated under conservative conditions showed that the contamination of water-supply wells would not exceed permissible concentration limits. 相似文献
69.
ELECTRE or Concordance Analysis is a French system of multicriteria analysis which is used in economics.The application of ELECTRE for hazard evaluation and risk assessment of chemical substances is suggested, and a first attempt in adapting it for this purpose is presented. 相似文献
70.
François Mermoud Fazil O. Gülaçar Samuel Siles Bernard Chassaing Armand Buchs 《Chemosphere》1982,11(6):557-567
Sediment cores from oxygen depleted zones of lake Léman (lake of Geneva) and from anoxic surface sediment from Voua de la Motte (France) were analyzed for their sterol compositions. 4-methylstanols were found to be major sterols in Motte lake sediment, which is rich in organic matter. In lake Léman, the relative abundances of the same 4-methylstanols increase with the depth in the core, but they remain always minor compounds. An extensive search for a possible external source for these compounds included the analysis of water, of the plankton and of the surrounding soil material. All these results, along with those of an in situ incubation experiment, give strong evidence in favor of their in situ bacterial biosynthesis. 相似文献