全文获取类型
收费全文 | 587篇 |
免费 | 26篇 |
国内免费 | 8篇 |
专业分类
安全科学 | 18篇 |
废物处理 | 13篇 |
环保管理 | 129篇 |
综合类 | 115篇 |
基础理论 | 171篇 |
环境理论 | 3篇 |
污染及防治 | 108篇 |
评价与监测 | 33篇 |
社会与环境 | 24篇 |
灾害及防治 | 7篇 |
出版年
2023年 | 10篇 |
2022年 | 9篇 |
2021年 | 20篇 |
2020年 | 27篇 |
2019年 | 25篇 |
2018年 | 27篇 |
2017年 | 29篇 |
2016年 | 31篇 |
2015年 | 35篇 |
2014年 | 23篇 |
2013年 | 48篇 |
2012年 | 38篇 |
2011年 | 56篇 |
2010年 | 31篇 |
2009年 | 21篇 |
2008年 | 30篇 |
2007年 | 32篇 |
2006年 | 30篇 |
2005年 | 20篇 |
2004年 | 10篇 |
2003年 | 17篇 |
2002年 | 10篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 8篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有621条查询结果,搜索用时 15 毫秒
161.
In recent years, the use of postfire mulch treatments to stabilize slopes and reduce soil erosion in shrubland ecosystems
has increased; however, the potential effects on plant recovery have not been examined. To evaluate the effects of mulching
treatments on postfire plant recovery in southern California coastal sage scrub, we conducted a field experiment with three
experimental treatments, consisting of two hydromulch products and an erosion control blanket, plus a control treatment. The
area burned in 2007, and treatments were applied to six plot blocks before the 2008 growing season. Treatment effects on plant
community recovery were analyzed with a mixed effects ANOVA analysis using a univariate repeated measures approach. Absolute
plant cover increased from 13 to 90% by the end of the second growing season, and the mean relative cover of exotic species
was 32%. The two hydromulch treatments had no effect on any plant community recovery response variable measured. For the erosion
control blanket treatment, the amount of bare ground cover at the end of the second growing season was significantly lower
(P = 0.01), and greater shrub height was observed (P < 0.01). We conclude that postfire mulch treatments did not provide either a major benefit or negative impact to coastal
sage scrub recovery on the study area. 相似文献
162.
Sarah E. Rothenberg Lester McKee Alicia Gilbreath Donald Yee Mike Connor Xuewu Fu 《Atmospheric environment (Oxford, England : 1994)》2010,44(10):1255-1262
Hg species (total mercury, methylmercury, reactive mercury) in precipitation were investigated in the vicinity of the Lehigh Hanson Permanente Cement Plant in the San Francisco Bay Area, CA., USA. Precipitation was collected weekly between November 29, 2007 and March 20, 2008, which included the period in February and March 2008 when cement production was minimized during annual plant maintenance. When the cement plant was operational, the volume weighted mean (VWM) and wet depositional flux for total Hg (HgT) were 6.7 and 5.8 times higher, respectively, compared to a control site located 3.5 km east of the cement plant. In February and March, when cement plant operations were minimized, levels were approximately equal at both sites (the ratio for both parameters was 1.1). Due to the close proximity between the two sites, meteorological conditions (e.g., precipitation levels, wind direction) were similar, and therefore higher VWM HgT levels and HgT deposition likely reflected increased Hg emissions from the cement plant. Methylmercury (MeHg) and reactive Hg (Hg(II)) were also measured; compared to the control site, the VWM for MeHg was lower at the cement plant (the ratio = 0.75) and the VWM for Hg(II) was slightly higher (ratio = 1.2), which indicated the cement plant was not likely a significant source of these Hg species to the watershed. 相似文献
163.
Nitrogen (N) pollution is a growing concern in forests of the greater Sierra Nevada, which lie downwind of the highly populated
and agricultural Central Valley. Nitrogen content of Letharia vulpina tissue was analyzed from 38 sites using total Kjeldahl analysis to provide a preliminary assessment of N deposition patterns.
Collections were co-located with plots where epiphytic macrolichen communities are used for estimating ammonia (NH3) deposition. Tissue N ranged from 0.6% to 2.11% with the highest values occurring in the southwestern Sierra Nevada (range:
1.38 to 2.11). Tissue N at 17 plots was elevated, as defined by a threshold concentration of 1.03%. Stepwise regression was
used to determine the best predictors of tissue N from among a variety of environmental variables. The best model consisted
only of longitude (r
2 = 0.64), which was reflected in the geographic distribution of tissue values: the southwestern Sierra Nevada, the high Sierras
near the Tahoe Basin, and the Modoc Plateau, are three apparent N hotspots arranged along the tilted north–south axis of the
study area. Withholding longitude and latitude, the best regression model suggested that NH3 estimates and annual number of wetdays interactively affect N accumulation (r
2 = 0.61; % N ∼ NH3 + wetdays + (NH3 × wetdays)). We did not expect perfect correspondence between tissue values and NH3 estimates since other N pollutants also accumulate in the lichen thallus. Additionally, other factors potentially affecting
N content, such as growth rate and leaching, were not given full account. 相似文献
164.
Bruce Thompson J. Ananda Ranasinghe Sarah Lowe Aroon Melwani Stephen B. Weisberg 《Environmental monitoring and assessment》2013,185(3):2281-2295
The spatial and temporal distribution of macrobenthic assemblages in the San Francisco Estuary and Sacramento–San Joaquin River Delta were identified using hierarchical cluster analysis of 501 samples collected between 1994 and 2008. Five benthic assemblages were identified that were distributed primarily along the salinity gradient: (1) a polyhaline assemblage that inhabits the Central Bay, (2) a mesohaline assemblage that inhabits South Bay and San Pablo Bay, (3) a low-diversity oligohaline assemblage primarily in Suisun Bay, (4) a low-diversity sand assemblage that occurs at various locations throughout the Estuary, and (5) a tidal freshwater assemblage in the Delta. Most sites were classified within the same assemblage in different seasons and years, but a few sites switched assemblage designations in response to seasonal changes in salinity from freshwater inflows. 相似文献
165.
The effect of visitors' pressure on the spatial variability of soil properties was investigated in three open green areas in Tel Aviv. Six types of micro-environments were chosen: under oak and pine tree canopy with low (OL and PL) and high (OH and PH) visitors' pressure; herbaceous area without visitors' pressure (HE); and resting area under high visitors' pressure (RA). For each micro-environment soil samples were collected from the upper 0-5 cm depth for organic matter content and moisture determination. Before sampling, soil surface compaction and litter biomass were measured. Soil properties were affected by visitors' pressure and by the type of micro-environment. Soil organic matter content and soil moisture proved significantly higher under oak trees at low visitors' pressure. Average litter biomass significantly decreased with increasing visitors' pressure in the tree micro-environments. Average penetration depth decreased significantly with increased visitors' pressure in all micro-environments. In all the cases where averages significantly decreased, variance significantly decreased too, but the coefficient of variations increased. This means that variances changed slower than averages. Changes in averages were accompanied by a change of data population structure, which indicated more soil spatial homogeneity under high visitors' pressure. The data from different intervals of data population of soil properties demonstrated the different sensitivity to visitors' pressure. 相似文献
166.
Sophie?GourguetEmail author Olivier?Thébaud Sarah?Jennings L.?Richard?Little Catherine?M.?Dichmont Sean?Pascoe Roy?A.?Deng Luc?Doyen 《Environmental Modeling and Assessment》2016,21(3):371-389
Fisheries management must address multiple, often conflicting objectives in a highly uncertain context. In particular, while the bio-economic performance of trawl fisheries is subject to high levels of biological and economic uncertainty, the impact of trawling on broader biodiversity is also a major concern for their management. The purpose of this study is to propose an analytical framework to formally assess the trade-offs associated with balancing biological, economic and non-target species conservation objectives. We use the Australian Northern Prawn Fishery (NPF), which is one of the most valuable federally managed commercial fisheries in Australia, as a case study. We develop a stochastic co-viability assessment of the fishery under multiple management objectives. Results show that, due to the variability in the interactions between the fishery and the ecosystem, current management strategies are characterized by biological and economic risks. Results highlight the trade-offs between respecting biological, economic and non-target species conservation constraints at each point in time with a high probability and maximizing the net present value of the fishery. 相似文献
167.
Marie E. DeLorenzo Sarah C. Wallace Loren E. Danese Thomas D. Baird 《Journal of environmental science and health. Part. B》2013,48(5):455-460
This study investigated the effects of increased temperature and salinity, two potential impacts of global climate change, on the toxicity of two common pesticides to the estuarine grass shrimp, Palaemonetes pugio. Larval and adult grass shrimp were exposed to the fungicide chlorothalonil and the insecticide Scourge® under standard toxicity test conditions, a 10°C increase in temperature, a 10 ppt increase in salinity, and a combined increased temperature and salinity exposure. Toxicity of the fungicide chlorothalonil increased with temperature and salinity. Toxicity of the insecticide Scourge® also increased with temperature; while increased salinity reduced Scourge® toxicity, but only in adult shrimp. These findings suggest that changes in temperature and salinity may alter the toxicity of certain pesticides, and that the nature of the effect will depend on both the organism's life stage and the chemical contaminant. Standard toxicity bioassays may not be predictive of actual pesticide toxicity under variable environmental conditions, and testing under a wider range of exposure conditions could improve the accuracy of chemical risk assessments. 相似文献
168.
Shabir A. Dar Hui Tan Aaron D. Peacock Peter Jaffe Lucie N'Guessan Kenneth H. Williams Sarah Strycharz‐Glaven 《补救:环境净化治理成本、技术与工艺杂志》2013,23(2):31-49
Analysis of the physiological status of subsurface microbial communities generally relies on the study of unattached microorganisms in the groundwater. These approaches have been employed in studies on bioremediation of uranium‐contaminated groundwater at a study site in Rifle, Colorado, in which Geobacter species typically account for over 90 percent of the microbial community in the groundwater during active uranium reduction. However, to develop efficient in situ bioremediation strategies it is necessary to know the status of sediment‐associated microorganisms as well. In order to evaluate the distribution of the natural community of Geobacter during bioremediation of uranium, subsurface sediments were packed into either passive flux meters (PFMs) or sediment columns deployed in groundwater monitoring wells prior to acetate injection during in situ biostimulation field trials. The trials were performed at the Department of Energy's (DOE's) Rifle Integrated Field Research Challenge site. Sediment samples were removed either during the peak of Fe(III) reduction or the peak of sulfate reduction over the course of two separate field experiments and preserved for microscopy. Direct cell counts using fluorescence in situ hybridization (FISH) probes targeting Geobacter species indicated that the majority of Geobacter cells were unattached during Fe(III) reduction, which typically tracks with elevated rates of uranium reduction. Similar measurements conducted during the sulfate‐reducing phase revealed the majority of Geobacter to be attached following exhaustion of more readily bioavailable forms of iron minerals. Laboratory sediment column studies confirmed observations made with sediment samples collected during field trials and indicated that during Fe(III) reduction, Geobacter species are primarily unattached (90 percent), whereas the majority of sulfate‐reducing bacteria and Geobacter species are attached to sediment surfaces when sulfate reduction is the predominant form of metabolism (75 percent and 77 percent, respectively). In addition, artificial sediment experiments showed that pure cultures of Geobacter uraniireducens, isolated from the Rifle site, were primarily unattached once Fe(III) became scarce. These results demonstrate that, although Geobacter species must directly contact Fe(III) oxides in order to reduce them, cells do not firmly attach to the sediments, which is likely an adaptive response to sparsely and heterogeneously dispersed Fe(III) minerals in the subsurface. © 2013 Wiley Periodicals, Inc. 相似文献
169.
One of the chemical breakdown products of nonylphenol ethoxylates, 4-nonylphenol (4-NP), accumulates in organisms and is of concern as an environmental pollutant due to its endocrine disrupting effects. We measured 4-NP levels in the seawater, sediment, and twelve organisms within the California estuary, Morro Bay, and examined biomagnification of 4-NP using stable isotope abundances (δ15N and δ13C) to quantify trophic position. 4-NP concentrations in organisms from Morro Bay included 25000 ± 8600 ng g−1 lw in liver of California sea lion, 14000 ± 5600 ng g−1 lw in liver of harbor porpoise, 138000 ± 55000 ng g−1 lw in liver of sea otters, 15700 ± 3600 ng g−1 lw in liver of seabirds, 36100 ± 6100 ng g−1 lw in arrow goby fish, 62800 ± 28400 ng g−1 lw in oysters, and 12700 ± 1300 ng g−1 lw in mussels. 4-NP levels generally showed a pattern of trophic dilution among organisms in Morro Bay, with exceptions of biomagnification observed between three trophic links: mussel to sea otter (BMF 10.9), oyster to sea otter (BMF 2.2), and arrow goby to staghorn sculpin (BMF 2.7). Our examination of other west coast estuaries of USA and Canada revealed that mean 4-NP concentrations in gobies and mussels from Morro Bay were significantly higher than those from a more urbanized estuary, San Francisco Bay (goby: 11100 ± 3800 ng g−1 lw) and from a remote estuary, Bamfield Inlet, Canada (goby: 9000 ± 900 ng g−1 lw, mussel: 6100 ± 700 ng g−1 lw). Relative to other estuaries worldwide, 4-NP levels in seawater (0.42 ± 0.16 μg L−1) and sediment (53 ± 14 ng g−1 dw) of Morro Bay are low, but gobies and oysters have higher 4-NP levels than comparable fauna. 相似文献
170.
Uncertainties in projected ultraviolet (UV) radiation may lead to future increases in UV irradiation of freshwater lakes. Because dissolved organic carbon (DOC) is the main binding phase for mercury (Hg) in freshwater lakes, an increase in DOC photo-oxidation may affect Hg speciation and bioavailability. We quantified the effect of DOC concentration on the rate of abiotic DOC photo-oxidation for five lakes (DOC=3.27-12.3 mg L(-1)) in Kejimkujik National Park, Canada. Samples were irradiated with UV-A or UV-B radiation over a 72-h period. UV-B radiation was found to be 2.36 times more efficient at photo-oxidizing DOC than UV-A, with energy-normalized rates of dissolved inorganic carbon (DIC) production ranging from 3.8×10(-5) to 1.1×10(-4) mg L(-1)J(-1) for UV-A, and from 6.0×10(-5) to 3.1×10(-4) mg L(-1)J(-1) for UV-B. Energy normalized rates of DIC production were positively correlated with DOC concentrations. Diffuse integrated attenuation coefficients were quantified in situ (UV-A K(d)=0.056-0.180 J cm(-1); UV-B K(d)=0.015-0.165 J cm(-1)) and a quantitative depth-integrated model for yearly DIC photo-production in each lake was developed. The model predicts that, UV-A produces between 3.2 and 100 times more DIC (1521-2851 mg m(-2) year(-1)) than UV-B radiation (29.17-746.7 mg m(-2) year(-1)). Future increases in UV radiation may increase DIC production and increase Hg bioavailability in low DOC lakes to a greater extent than in high DOC lakes. 相似文献