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521.
de Figueiredo DR Ferreira RV Cerqueira M de Melo TC Pereira MJ Castro BB Correia A 《Environmental monitoring and assessment》2012,184(1):471-485
The information on bacterial community composition (BCC) in Portuguese water bodies is very scarce. Cértima River (central
western Portugal) is known to have high levels of pollution, namely organic. In the present work, the BCC from a set of 16
water samples collected from Cértima River Basin and its main tributaries was characterized using 16S rDNA–denaturing gradient
gel electrophoresis, a culture-independent molecular approach. Molecular data were related to environmental parameters through
multivariate analysis to investigate potential impact of water pollution along the river. Principal component analysis using
environmental data showed a water quality gradient from more pristine waters (at the mountain tributaries) to waters with
increasingly eutrophic potential (such as Fermentelos Lake). This gradient was mainly defined by factors such as organic and
inorganic nutrient sources, electrical conductivity, hydrogen carbonate concentration, and pH. Molecular results showed variations
in BCC along Cértima River Basin but in the main river section, a Bacteroidetes phylotype (Flavobacterium sp.) proved to be dominant throughout the river course. Multivariate analysis suggests that spatial variation of BCC along
the Cértima River Basin depended mainly on parameters such as Chl a, total suspended solid (TSS), total organic carbon, electrical conductivity, and HCO
_boxclose^-_{3}^{-} levels. Bacteroidetes phylotypes were all related to higher electrical conductivity and HCO3-_{3}^{-} levels although some of these were also correlated with high SO42-_{4}^{2-} and others with high soluble reactive phosphorus, nitrate, TN, and Kjeld-N levels. The Gammaproteobacteria occurrence was correlated with high SO42-_{4}^{2-} levels. One of the Betaproteobacteria phylotypes showed to correlate with low redox potential (Eh) and high temperature, pH, TSS, and Chl a levels while another one showed a negative correlation with Chl a values. 相似文献
522.
Chlorinated paraffins (CPs) are straight chain hydrocarbons that are produced as complex mixtures and are used as flame retardants
and paint additives. These mixtures are extremely difficult to characterize using conventional chromatographic methods, as
conventional gas chromatography results in unresolved complex chromatograms that preclude the identification and quantification
of individual congeners or any reasonable assessment of the average carbon chain length. Carbon chain length is an important
parameter for assessing physical properties and the toxicity of these materials. We have modified and improved a previously
published gas chromatography–flame ionization detector method that uses Pd catalyst held in the gas chromatograph injector
to simultaneously dechlorinate the CPs and separate the resulting alkanes. In addition, we have adapted this method to gas
chromatography–mass spectrometry. Dehalogenation of other compounds was also studied with this system to investigate potential
application to other complex halogenated mixtures. 相似文献
523.
A sensitive spectrophotometric method has been developed for determination of ametryn in agricultural samples. The proposed
method was based on reaction with pyridine and further coupling with sulfanilic acid to form a colored product. The absorbance
was measured at 400 nm with a molar absorptivity of 2.1 × 105 L mol−1 cm−1. The method shows a linear range from 0.2–20 μg mL−1 with limit of detection and limit of quantification 0.16 and 0.54 μg mL−1, respectively. The method has been successfully applied to the determination of ametryn in sugarcane juice and commercial
formulations after separation of ametryn from triazine herbicides based on solvent extraction. Recovery values were found
to be in the range of 96.0 ± 0.2% to 98.4 ± 0.1%. 相似文献
524.
Gas–particle concentration,distribution, and health risk assessment of polycyclic aromatic hydrocarbons at a traffic area of Giza,Egypt 总被引:1,自引:0,他引:1
Atmospheric particulate and gaseous polycyclic aromatic hydrocarbons (PAHs) samples were collected from an urban area in Dokki
(Giza) during the summer of 2007 and the winter of 2007–2008. The average concentrations of PAHs were 1,429.74 ng/m3 in the particulate phase, 2,912.56 ng/m3 in the gaseous phase, and 4,342.30 ng/m3 in the particulate + gaseous phases during the period of study. Dokki has high level concentrations of PAH compounds compared
with many polluted cities in the world. The concentrations of PAH compounds in the particulate and gaseous phases were higher
in the winter and lower in the summer. Total concentrations of PAHs in the particulate phase and gaseous phase were 22.58%
and 77.42% in summer and 36.97% and 63.03% in winter of the total (particulate + gaseous) concentrations of PAHs, respectively.
The gaseous/particulate ratios of PAHs concentration were 3.43 in summer and 1.71 in winter. Significant negative correlation
coefficients were found between the ambient temperature and concentrations of the total PAHs in the particulate and gaseous
phases. The distribution of individual PAHs and different categories of PAHs based on aromatic ring number in the particulate
and gaseous phases during the summer and winter were nearly similar, indicating similar emission sources of PAHs in both two
seasons. Benzo(b)fluoranthene in the particulate phase and naphthalene in the gaseous phase were the most abundant compounds. Diagnostic concentration
ratios of PAH compounds indicate that these compounds are emitted mainly from pyrogenic sources, mainly local vehicular exhaust
emissions. Health risks associated with the inhalation of individual PAHs in particulate and gaseous phases were assessed
on the basis of its benzo(a)pyrene equivalent concentration. Dibenzo(a,h)anthracene and benzo(a)pyrene in the particulate phase and benzo(a)pyrene and benzo(a)anthracene in the gaseous phase were the greatest contributors to the total health risks. The relative mean contributions
of the total carcinogenic activity (concentrations) of all PAHs to the total concentrations of PAHs were 29.37% and 25.15%
in the particulate phase and 0.76% and 0.92% in the gaseous phase during the summer and winter, respectively. These results
suggest that PAHs in the particulate phase in the ambient air of Dokki may pose a potential health risk. 相似文献
525.
Fernandes CE Das A Nath BN Faria DG Loka Bharathi PA 《Environmental monitoring and assessment》2012,184(5):2677-2689
We investigated the influence on bacterial community and biochemical variables through mechanical disturbance of sediment-akin
to small-scale mining in Kalbadevi beach, Ratnagiri, a placer-rich beach ecosystem which is a potential mining site. Changes
were investigated by comparing three periods, namely phase I before disturbance, phase II just after disturbance, and phase
III 24 h after disturbance as the bacterial generation time is ≤7 h. Cores from dune, berm, high-, mid-, and low-tide were
examined for changes in distribution of total bacterial abundance, total direct viability (counts under aerobic and anaerobic
conditions), culturability and biochemical parameters up to 40 cm depth. Results showed that bacterial abundance decreased
by an order from 106 cells g − 1 sediment, while, viability reduced marginally. Culturability on different-strength nutrient broth increased by 155% during
phase II. Changes in sedimentary proteins, carbohydrates, and lipids were marked at berm and dune and masked at other levels
by tidal influence. Sedimentary ATP reduced drastically. During phase III, Pearson’s correlation between these variables evolved
from non-significant to significant level. Thus, simulated disturbance had a mixed effect on bacterial and biochemical variables
of the sediments. It had a negative impact on bacterial abundance, viability and ATP but positive impact on culturability.
Viability, culturability, and ATP could act as important indicators reflecting the disturbance in the system at short time
intervals. Culturability, which improved by an order, could perhaps be a fraction that contributes to restoration of the system
at bacterial level. This baseline information about the potential mining site could help in developing rational approach towards
sustainable harnessing of resources with minimum damage to the ecosystem. 相似文献
526.
The increasing urbanization, along with tourism, has posed a major threat to the Kumaun Himalayan Lakes, Uttarakhand, India.
The total metal concentration in the water, interstitial water, and sediments along with the metal fractionation studies were
carried out to understand the remobilization of the trace metals from the sediments of the lakes. The high concentration of
the metals in the water column of the lakes generally decreases with depth and the metals release from the sediment is mainly
due to the prevalence of anoxic condition at the sediment–water interface and sediment column. The sediment shows that metals
Fe and Cr are derived from detrital source, whereas Co, Ni, and Zn are derived mainly from the organic matter dissolution.
The sparse correlation of the trace metals with Ti shows most of the metals have chiefly re-precipitated from the water column.
The metals speciation studies also supports that metals experience a high rate of anoxic dissolution and their precipitation
onto the sediments are determined by the sediment composition and organic matter content. The high concentration of manganese
in the interstitial water in the lakes indicates dissolution of organic matter. The released manganese is adsorbed/precipitated
as carbonate phase (Nainital Lake) and oxide pahse (in other lakes). The study shows that the trace metals are regenerated
from the sediments due to oxyhydroxide dissolution and organic matter decomposition. 相似文献
527.
Langston WJ O'Hara S Pope ND Davey M Shortridge E Imamura M Harino H Kim A Vane CH 《Environmental monitoring and assessment》2012,184(1):289-311
Biomonitoring of contaminants (metals, organotins, polyaromatic hydrocarbons (PAHs), PCBs) was undertaken in Milford Haven
Waterway (MHW) and a reference site in the Tywi Estuary (St Ishmael/Ferryside) during 2007–2008. Bioindicator species encompassed
various uptake routes—Fucus vesiculosus (dissolved contaminants); Littorina littorea (grazer); Mytilus edulis and Cerastoderma edule (suspension feeders); and Hediste (=Nereis) diversicolor (sediments). Differences in feeding and habitat preference have subtle implications for bioaccumulation trends though, with
few exceptions, contaminant burdens in MHW were higher than the Tywi reference site, reflecting inputs. Elevated metal concentrations
were observed at some MHW sites, whilst As and Se (molluscs and seaweed) were consistently at the higher end of the UK range.
However, for most metals, distributions in MH biota were not exceptional. Several metal-species combinations indicated increases
in bioavailability upstream, which may reflect the influence of geogenic/land-based sources—perhaps enhanced by lower salinity.
TBT levels in MH mussels were below OSPAR toxicity thresholds and in the Tywi were close to zero. Phenyltins were not accumulated
appreciably in M. edulis, whereas some H. diversicolor populations appear subjected to localized (historical) sources. PAHs in H. diversicolor were distributed evenly across most of MHW, although acenaphthene, fluoranthene, pyrene, benzo(a)anthracene and chrysene were highest at one site near the mouth; naphthalenes in H. diversicolor were enriched in the mid-upper Haven (a pattern seen in M. edulis for most PAHs). Whilst PAH (and PCB) concentrations in MH mussels were mostly above reference and OSPAR backgrounds, they
are unlikely to exceed ecotoxicological thresholds. Bivalve Condition indices (CI) were highest at the Tywi reference site
and at the seaward end of MH, decreasing upstream—giving rise to several significant (negative) relationships between CI and
body burdens. Despite the possible influence of salinity gradient as a complicating factor, multivariate analysis indicated
that a combination of contaminants could influence the pattern in condition (and the biomarkers metallothionein and TOSC).
Integrating bioaccumulation data with biological and biochemical endpoints is seen as a useful way to discriminate environmental
quality of moderately contaminated areas such as MHW and to prioritise cause and effect investigations. 相似文献
528.
Drinking water samples collected from rural areas of three districts of Haryana during pre-monsoon and post-monsoon periods
were analysed for the presence of organochlorine pesticide residues. The main source of drinking water in rural areas, i.e.
groundwater in Ambala and Gurgaon districts and surface water supply in Hisar district, was found to be contaminated with
isomers of HCH and endosulfan and metabolites of DDT, whereas dieldrin remained below detection limits. During the study period,
the mean values observed for total HCH, DDT and endosulfan were 87.6, 848.2, and 27.4 ng/L and 99.8, 275.3 and 164.2 ng/L,
respectively, for Ambala and Gurgaon districts. In the case of Hisar district, the values were 78.5, 115.9, and 53.0 ng/L,
respectively. During the study period, 37% of the samples exceeded the total pesticide level of 500 ng/L indicated in the
EECD directive for drinking water. Seasonal variations of pesticide residues were also observed during the study period. 相似文献
529.
Assessment of drinking water quality using ICP-MS and microbiological methods in the Bholakpur area,Hyderabad, India 总被引:1,自引:0,他引:1
Abdul RM Mutnuri L Dattatreya PJ Mohan DA 《Environmental monitoring and assessment》2012,184(3):1581-1592
A total of 16 people died and over 500 people were hospitalized due to diarrhoeal illness in the Bholakpur area of Hyderabad,
India on 6th May 2009. A study was conducted with immediate effect to evaluate the quality of municipal tap water of the Bholakpur
locality. The study consists of the determination of physico-chemical properties, trace metals, heavy metals, rare earth elements
and microbiological quality of drinking water. The data showed the variation of the investigated parameters in samples as
follows: pH 7.14 to 8.72, EC 455 to 769 μS/cm, TDS 303.51 to 515.23 ppm and DO 1.01 to 6.83 mg/L which are within WHO guidelines
for drinking water quality. The water samples were analyzed for 27 elements (Li, Be, B, Na, Mg, Al, Si, K, Ca, V, Cr, Mn,
Fe, Ni, Co, Cu, Zn, As, Se, Rb, Sr, Mo, Ag, Cd, Sb, Ba and Pb) using inductively coupled plasma-mass spectrometry (ICP-MS).
The concentrations of Fe (0.12 to 1.13 mg/L), Pb (0.01 to 0.07 mg/L), Cu (0.01 to 0.19 mg/L), Ni (0.01 to 0.15 mg/L), Al (0.16
to 0.49 mg/L), and Na (38.36 to 68.69 mg/L) were obtained, which exceed the permissible limits of the World Health Organization
(WHO) for drinking water quality guidelines. The remaining elements were within the permissible limits. The microbiological
quality of water was tested using standard plate count, membrane filtration technique, thermotolerant coliform (TTC), and
most probable number (MPN) methods. The total heterotrophic bacteria ranged from 1.0 × 105 to 18 × 107 cfu/ml. Total viable bacteria in all the water samples were found to be too numerable to count and total number of coliform
bacteria in all water samples were found to be of order of 1,100 to >2,400 MPN index/100 ml. TTC tested positive for coliform
bacteria at 44.2°C. All the water samples of the study area exceeded the permissible counts of WHO and that (zero and minimal
counts) of the control site (National Geophysical Research Institute) water samples. Excessively high colony numbers indicate
that the water is highly contaminated with microorganisms and is hazardous for drinking purposes. Bacteriological pollution
of drinking water supplies caused diarrhoeal illness in Bholakpur, which is due to the infiltration of contaminated water
(sewage) through cross connection, leakage points, and back siphoning. 相似文献
530.
Mayack DT 《Environmental monitoring and assessment》2012,184(4):2497-2516
Many non-linear processes link atmospheric emissions to the bioavailability of metals; consequently, the monitoring of metals
in ecosystem components is required to model their ecodynamics. American mink (Neovison vison) and river otter (Lontra canadensis) have the potential to serve as an upper-level-consumer component in monitoring metals bioavailability. However, the relationship
of bioaccumulated metals to various environmental factors has not been explored nor have the effects of demographic factors
been resolved. To address these limitations, mink and otter, collected throughout New York State during 1998–2002, were analyzed
for hepatic concentrations of total mercury (Hg), cadmium (Cd), and lead (Pb). Relationships were investigated between metals
concentrations and landscape-level factors (physiographic zone, hydrologic unit, and elevation) and demographic factors (gender
and age). Considerable variation in Hg and Cd concentrations was observed relative to both physiographic zone and hydrologic
unit for both species. In contrast with Hg, Cd concentration increased predictably with increasing elevation. Mercury concentrations
were greater, but for Cd less, in otter than mink. Lead concentrations showed little landscape heterogeneity and were independent
of elevation. Age-related bioaccumulation was evident for Hg and Cd, but not for Pb, in both species. Mercury and Cd concentrations
were greater in female than male mink; however, Pb concentrations were greater in males than females. Inverse relationships
of relative growth (weight/length) to metals concentrations explained gender differences in Hg and Cd in mink. For otter,
no gender-related differences in metals concentrations were apparent. The suitability of mink and otter for monitoring programs
is discussed. 相似文献