全文获取类型
收费全文 | 4276篇 |
免费 | 33篇 |
国内免费 | 13篇 |
专业分类
安全科学 | 52篇 |
废物处理 | 278篇 |
环保管理 | 255篇 |
综合类 | 679篇 |
基础理论 | 885篇 |
环境理论 | 4篇 |
污染及防治 | 1496篇 |
评价与监测 | 418篇 |
社会与环境 | 247篇 |
灾害及防治 | 8篇 |
出版年
2023年 | 44篇 |
2022年 | 139篇 |
2021年 | 128篇 |
2020年 | 47篇 |
2019年 | 56篇 |
2018年 | 158篇 |
2017年 | 117篇 |
2016年 | 218篇 |
2015年 | 116篇 |
2014年 | 251篇 |
2013年 | 426篇 |
2012年 | 259篇 |
2011年 | 258篇 |
2010年 | 201篇 |
2009年 | 151篇 |
2008年 | 235篇 |
2007年 | 239篇 |
2006年 | 219篇 |
2005年 | 146篇 |
2004年 | 119篇 |
2003年 | 107篇 |
2002年 | 92篇 |
2001年 | 59篇 |
2000年 | 46篇 |
1999年 | 35篇 |
1998年 | 14篇 |
1997年 | 14篇 |
1996年 | 8篇 |
1995年 | 25篇 |
1994年 | 18篇 |
1993年 | 14篇 |
1992年 | 7篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1982年 | 6篇 |
1970年 | 11篇 |
1967年 | 10篇 |
1966年 | 12篇 |
1965年 | 17篇 |
1964年 | 28篇 |
1963年 | 12篇 |
1962年 | 17篇 |
1961年 | 12篇 |
1960年 | 13篇 |
1959年 | 28篇 |
1958年 | 31篇 |
1957年 | 18篇 |
1956年 | 15篇 |
1955年 | 19篇 |
1954年 | 7篇 |
排序方式: 共有4322条查询结果,搜索用时 250 毫秒
211.
Germán A. Kopprio Gerhard Kattner R. Hugo Freije Susana José de Paggi Rubén J. Lara 《Environmental monitoring and assessment》2014,186(5):3139-3148
The seasonal variability of inorganic and organic nutrients and stable isotopes and their relations with plankton and environmental conditions were monitored in Lake Chasicó. Principal component analysis evidenced the strong influence of the river runoff on several biogeochemical variables. Silicate concentrations were controlled by diatom biomass and river discharge. Higher values of nitrate and soluble reactive phosphorus (SRP) indicated agricultural uses in the river basin. Elevated pH values (~9) inhibiting nitrification in the lake explained partially the dominance of ammonium: ~83 % of dissolved inorganic nitrogen (DIN). The low DIN/SRP ratio inferred nitrogen limitation, although the hypotheses of iron and CO2 limitation are relevant in alkaline lakes. Particulate organic matter (POM) and dissolved organic matter (DOM) were mainly of autochthonous origin. The main allochthonous input was imported by the river as POM owning to the arid conditions. Dissolved organic carbon was likely top-down regulated by the bacterioplankton grazer Brachionus plicatilis. The δ13C signature was a good indicator of primary production and its values were influenced probably by CO2 limitation. The δ15N did not evidence nitrogen fixation and suggested the effects of anthropogenic activities. The preservation of a good water quality in the lake is crucial for resource management. 相似文献
212.
Elena Crespo Pablo Lozano Julián Blasco Ignacio Moreno-Garrido 《Environmental monitoring and assessment》2014,186(8):4647-4654
Marine epibionts are organisms that grow on submerged surfaces. Those found on seagrass leaves are especially important because of their interactions with the plants, their contribution to primary production in these ecosystems, and their role as food source for heterotrophic fauna. Given the relative lack of ecotoxicological studies on epibionts, the aim of this study is to evaluate the effect of environmental pollution on epiphytes experimentally attached to artificial devices (mimes) consisting of thermally-sealed silicone tubes supported on bamboo sticks that mimic the morphology of seagrasses and serve as an anchor surface for marine epibionts. Mimes were installed on the sea floor in subtidal waters of the Rio San Pedro (Cádiz), collected after 28 days, and incubated in the laboratory with environmental concentrations of atrazine (herbicide), Irgarol (anti-fouling substance), and copper. Tube-dwelling diatoms formed the major component of the epiphyte community. Average surface covering, chlorophyll, and biomass content did not show significant differences between controls and treatments. The glutathione peroxidase activity increased significantly with 4 μg L?1 of atrazine and 5 μg L?1 of copper. This enzymatic activity increase seems to be sufficient to prevent oxidative cellular damage by removing reactive oxygen substances produced by oxidative stress; in addition to this enzyme, there might be other antioxidant enzymes which have not been measured in this study, that have also protected the organism from oxidative damage. Thus, the measurement of antioxidant enzymatic activity in epiphytes may be a useful toxicity indicator for coastal biomonitoring. 相似文献
213.
214.
The De?le River in Northern France experienced serious contamination from the metallurgical industry, especially from the smelter Metaleurop prior to 2003. In 2002 the surface sediments were collected from the bed of the river around 10 km above and 10 km below the smelter. Total mercury (HgT) and methylmercury (MeHg) concentrations exceeded the background value of 0.1 mg kg(-1). The average concentrations were 19.67 ± 1.02 mg kg(-1) and 10.88 ± 1.08 μg kg(-1), respectively. In 2003 the sediment core samples were collected at two different sites near the factory for survey depth profiles of Hg contamination. The concentrations of HgT and MeHg in sediment cores varied from 10.47 to 259.44 mg kg(-1) and from 3.24 to 82.61 μg kg(-1), respectively. The concentration of total mercury was significantly correlated with the methylmercury concentration in the sediment below a depth of 23.5 cm (R(2) = 0.81, p < 0.01). This may suggest that the production of MeHg is directly related to the HgT concentration. Nevertheless the MeHg/HgT ratio in the upper part of the sediment core was higher than that in the lower part. This suggests that HgT and MeHg may have been co-deposited together. However, the methylmercury production takes place in the surface sediment by microorganisms. The strong correlation observed between MeHg and acid volatile sulfides (AVS) suggests that MeHg variability is associated with the bacterial activity (presence of AVS). 相似文献
215.
rámek V Novotný R Vejpustková M Hůnová I Uhlířová H 《Journal of environmental monitoring : JEM》2012,14(6):1696-1702
The ozone effect on Norway spruce (Picea abies (L) Karst.) and European beech (Fagus sylvatica L.) was studied on 48 monitoring plots in 2005-2008. These plots represent two major forest tree species stands of different ages in eight regions of the Czech Republic. The forest conditions were represented by defoliation and the annual radial increment of individual trees. The ozone exposure was assessed by using modeled values of mean annual O(3) concentration and the AOT40 index. The malondialdehyde (MDA) content of the foliage was analysed and used as an indicator of oxidative stress. The correlation analysis showed a significant relation of Norway spruce defoliation to the AOT40 exposure index, and European beech defoliation to the MDA level. The radial increment response to ozone was significant only for the European beech: (a) the correlation analysis showed its decrease with increasing AOT40; (b) the regression model showed its decrease with increasing mean annual ozone concentration only at lower altitudes (<700 m a.s.l.). 相似文献
216.
Santacatalina M Yubero E Mantilla E Carratalá A 《Environmental monitoring and assessment》2012,184(11):6827-6844
This paper shows the changes in PM(10) levels and chemical composition in a region in southeast Spain between two periods: September 2005-August 2006 and June 2008-May 2009. PM(10) levels in this arid region, with a great number of cement, ceramic and related industries, have decreased in the second period in concordance with the reduction of industrial production due to the economic crisis and the closure of a cement plant. Annual average levels of PM(10) decreased from 41?μg?m(-3) in 2005 to 30?μg?m(-3) in 2008 (27%) and to 23?μg?m(-3) in 2009 (23%). The relative contribution of the different sources has not changed in the area in the latter period and the elements with mineral origin are the main components of the PM(10) composition. There is a reduction in the concentration of the components that have soil-related industries and crustal material resuspension as their main sources, mainly in the case of CO(3) (2-), Ca, Sr, Tl and Pb, but the seasonal patterns were the same in both periods. As a particular case, there is an uncoupling between the seasonal evolution of SO(2) and sulphates in the two study periods, which remarks the existence of a sulphate regional background that does not depend on SO(2) local emissions. The decrease of V, Ni and Tl levels reflects the reduction of the industrial activity during the crisis period, affecting mainly the ceramic sector characterised by a great decrease of Tl levels. 相似文献
217.
Brázová T Hanzelová V Miklisová D Salgovičová D Turčeková L 《Environmental monitoring and assessment》2012,184(11):6553-6561
The distribution and concentrations of polychlorinated biphenyls (PCBs) were determined in fish species (European perch Perca fluviatilis, northern pike Esox lucius, pike perch Sander lucioperca, wels catfish Silirus glanus, common carp Cyprinus carpio, European eel Anguilla anguilla, freshwater bream Abramis brama, goldfish Carassius auratus, and roach Rutilus rutilus) in a heavily polluted water reservoir Zemplínska ?írava (Slovakia). The study performed at two different time points 5?years apart (2004 and 2009) revealed serious PCB contamination of fish muscle tissue and significant interspecies as well as tissue-specific differences in PCB uptake by fish. Total PCBs broadly correlated with the trophic position of individual fish species within a food chain (P?0.01). The concentrations were particularly high in predatory fish species, perch, pike, and pike perch (108.0, 90.1, and 113.0?mg?kg(-1) lipid wt, respectively), but comparable PCB values were also found in non-predatory detrivorous freshwater bream (128.0?mg?kg(-1) lipid wt). The lowest PCB values were surprisingly assessed in European eel (17.1?mg?kg(-1) lipid wt). Tissue analysis showed the highest storage capacity of the liver (hepatopancreas in cyprinids) with maximum concentrations recorded found in northern pike (214.0?mg?kg(-1) lipid wt) and freshwater bream (163.0?mg?kg(-1) lipid wt). Negative correlations, mostly not significant, between the total PCB concentrations and fish weight were observed (P?>?0.05). The study has shown that the kind of fish, its feeding habit, and specific conditions of the habitat are mutually interrelated factors that are responsible for significant variations in fish body burdens. A tendency to PCB biomagnification was also proved in some fish species of this water reservoir. 相似文献
218.
In 1998, the Agrio and Guadiamar rivers underwent an enormous environmental disaster caused by the rupture of the Aznalcóllar
tailings dam and the release of 6 hm3 of pyrite sludge and acidic water. Both rivers run over recent alluvial materials which form a small-sized aquifer which
is however important because underground water feeds the flow of the rivers. This work analyzes the state of groundwater 10 years
after the spill. Before the dam failure, this aquifer was already contaminated in the zone nearest to the mine, to which the
impact of the spill was added. Contamination levels in the alluvial aquifer of the Agrio River have decreased remarkably.
However, they are still important, with acidic pH values and high concentrations of toxic elements (maximum values of 16 mg/L
of Zn and 15 mg/L of Al). There are also important levels of contamination in the Guadiamar alluvial area closest to the mine,
as well as in specific zones located further south. The concentration of toxic elements is mainly controlled by pH. The evolution
of contaminant levels show a sharp decrease after the first years following the spill, followed by a subsequent stabilization.
It is necessary to take measures for the recovery of the aquifer because, otherwise, groundwater will continue contributing
contaminants into the Agrio and Guadiamar rivers. 相似文献
219.
Caetano M Bernárdez P Santos-Echeandia J Prego R Vale C 《Environmental monitoring and assessment》2012,184(11):6541-6552
Short-sediment cores and flooding water were collected at 0, 5, 15, 25 and 50?min of tidal inundation in the two sites colonised by pure stands of Spartina maritima (low marsh) and Sarcocornia fruticosa (high marsh) from the Rosário salt marsh (Tagus estuary, SW Europe). Concentrations of NH (4) (+) , NO (3) (-) +?NO (2) (-) and HPO (4) (2-) , Fe and Mn were measured in tidal flooding water and pore water. Flooding water is enriched in nutrients, particularly ammonium due to local discharge of untreated urban effluents. Nevertheless, NH (4) (+) and NO (3) (-) +?NO (2) (-) concentrations in flooding waters at t?=?5?min (NH (4) (+) =?246?±?7?μM, NO (3) (-) +?NO (2) (-) =?138?±?1?μM for S. fruticosa and NH (4) (+) =?256?±?8?μM, NO (3) (-) +?NO (2) (-) =?138?±?1?μM for S. maritima) rose sharply at both vegetated sites. An increase was also registered for HPO (4) (2-) and total dissolved Fe although the subsequent decrease was smoother. Advective transport induced by the two daily pulses of inundation is several orders of magnitude higher than the diffusive fluxes during submerged periods. In addition, solutes are exported from the sediment with the inundation and imported in submerged periods. The exported amount of inorganic nitrogen during tidal inundation (export of 3,200?μmol?N?m(-2)?day(-1)to the water column), is not counterbalanced by the sink of -290?μmol?N?m(-2)?day(-1) occurred during the submerged period. 相似文献
220.
Markovics R Kanduč T Szramek K Golobočanin D Milačič R Ogrinc N 《Journal of environmental monitoring : JEM》2010,12(11):2165-2176
Presented here is a study of the geochemical dynamics of the entire River Sava watershed, a major tributary of the River Danube which has not previously been investigated. The sampling was performed at 33 selected locations along the main channel of the stream and at its largest tributaries during three sampling seasons (fall 2005, spring 2006 and fall 2006), going from headwater locations to the mouth near the confluence with the Danube. Almost 80% of the solutes are derived from carbonate mineral weathering and represent over 50% of specific HCO(3)(-) flux normalized to unit basin area at the mouth of the Danube. Statistical analysis indicates that agricultural and industrial sources contribute significantly to increased Na(+), K(+), Cl(-), SO(4)(2-) and NO(3)(-) concentrations in tributary waters. Different processes control the water chemistry along the course of the Sava's drainage-the upper reaches are largely regulated by contributions from carbonate mineral weathering, the middle reaches are influenced by agricultural activity and biological processes related to eutrophication, while the lower reaches tend to have more pronounced parameters related to the industrial processing along with leakages from municipal sanitary systems of these higher population density areas. 相似文献