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941.
Multiresidue analysis of pesticides in fruits and vegetables by gas chromatography-mass spectrometry
Araoud M Douki W Rhim A Najjar MF Gazzah N 《Journal of environmental science and health. Part. B》2007,42(2):179-187
A multiresidue method was assessed for the determination of several pesticides (organochlorine, organophosphorus, pyrethroids, triazole, amidine) using gas chromatography/mass spectrometry. The extraction of pesticides was carried out by liquid-liquid extraction (LLE) and solid-phase extraction (SPE) using two types of columns (CN and C18). The extracts were cleaned by the addition of florisil, the pesticides were separated by capillary column gas chromatography and detected by mass spectrometry in the electron impact mode. The extraction using C18 column provided the best results for most of the analyzed pesticides. The majority of pesticides recoveries from the four fruits and vegetables (apples, pears, tomatoes and pepper) were greater than 60%. Linearity and precision were satisfactory. The estimated limits of detection and limits of quantification ranged from 0.01 to 0.1 mg/kg and from 0.02 to 0.3 mg/kg, respectively. The proposed procedure was found to be useful for the multiresidue analyses of pesticides in agricultural products for routine monitoring programs. 相似文献
942.
The Distribution and Sources of Polycyclic Aromatic Hydrocarbons in Surface Sediments Along the Egyptian Mediterranean Coast 总被引:2,自引:0,他引:2
El Nemr A Said TO Khaled A El-Sikaily A Abd-Allah AM 《Environmental monitoring and assessment》2007,124(1-3):343-359
Coastal marine sediment samples were collected from 31 sampling stations along the Egyptian Mediterranean Sea coast. All sediment
samples were analyzed to determine aliphatic and polycyclic aromatic hydrocarbons (PAHs) as well as total organic carbon (TOC)
contents and grain size analysis. Total concentrations of 16 EPA-PAHs in the sediments were varied from 88 to 6338 ng g−1 with an average value of 154 ng g−1 (dry weight). However, the concentrations of total aliphatic were varied from 1.3 to 69.9 ng g−1 with an average value of 15.6 ng g−1 (dry weight). The highest contents of PAHs were found in the Eastern harbor (6338 ng g−1), Manzala (5206 ng g−1) and El-Jamil East (4895 ng g−1) locations. Good correlations observed between a certain numbers of PAH concentrations allowed to identify its origin. The
average total organic carbon (TOC) percent was varied from 0.91 to 4.54%. Higher concentration of total pyrolytic hydrocarbons
(∑COMB) than total fossil hydrocarbons (∑PHE) declared that atmospheric fall-out is the significant source of PAHs to marine
sediments of the Egyptian Mediterranean coast. The selected marked compounds, a principal component analysis (PCA) and special
PAHs compound ratios (phenanthrene/anthracene vs fluoranthene/pyrene; ∑COMB/∑EPA-PAHs) suggest the pyrogenic origins, especially
traffic exhausts, are the dominant sources of PAHs in most locations. Interferences of rather petrogenic and pyrolytic PAH
contaminations were noticed in the harbors due to petroleum products deliveries and fuel combustion emissions from the ships
staying alongside the quays. 相似文献
943.
The level of concentrations of polycyclic aromatic hydrocarbons (PAHs) in surface soils from petroleum handling facilities
(kerosene tank, generating plant, petrol stations, mechanic workshops, leaking pipeline and air port fuel dump) from Calabar
metropolis southeastern Nigeria was determined by gas chromatography/ mass spectrometry. The results show that total polycyclic
aromatic hydrocarbons (PAHs) varied from 1.80 to 334.43 mg/kg with a mean of 50.31 mg/kg. The lowest value of 1.80 mg/kg was
obtained from petrol station while the highest value of 334.43 mg/kg was obtained from facility characterised by petrol stations
and mechanic workshops. The ratio of phenanthrene/anthracene and fluoranthene/pyrene, varied from 0.43 to 27.72 and from 0.14
to 17.76 respectively. These ratios indicate various sources for the PAH. The two to three ring PAHs are the most abundant.
Based on the PAH ratios and content alone it is not possible to distinguish between contribution from motor vehicle exhaust,
gasoline spillage, used engine oil or petroleum production. However, considering the area of the study, it is very likely
that the major source of soil contamination is originating from petroleum product. 相似文献
944.
Lemly AD 《Environmental monitoring and assessment》2007,125(1-3):361-375
This paper gives step-by-step instructions for assessing aquatic selenium hazards associated with mining. The procedure was
developed to provide the U.S. Forest Service with a proactive capability for determining the risk of selenium pollution when
it reviews mine permit applications in accordance with the National Environmental Policy Act (NEPA). The procedural framework
is constructed in a decision-tree format in order to guide users through the various steps, provide a logical sequence for
completing individual tasks, and identify key decision points. There are five major components designed to gather information
on operational parameters of the proposed mine as well as key aspects of the physical, chemical, and biological environment
surrounding it — geological assessment, mine operation assessment, hydrological assessment, biological assessment, and hazard
assessment. Validation tests conducted at three mines where selenium pollution has occurred confirmed that the procedure will
accurately predict ecological risks. In each case, it correctly identified and quantified selenium hazard, and indicated the
steps needed to reduce this hazard to an acceptable level. By utilizing the procedure, NEPA workers can be confident in their
ability to understand the risk of aquatic selenium pollution and take appropriate action. Although the procedure was developed
for the Forest Service it should also be useful to other federal land management agencies that conduct NEPA assessments, as
well as regulatory agencies responsible for issuing coal mining permits under the authority of the Surface Mining Control
and Reclamation Act (SMCRA) and associated Section 401 water quality certification under the Clean Water Act. Mining companies
will also benefit from the application of this procedure because priority selenium sources can be identified in relation to
specific mine operating parameters. The procedure will reveal the point(s) at which there is a need to modify operating conditions
to meet environmental quality goals. By recognizing concerns early in the NEPA process, it may be possible for a mining company
to match operational parameters with environmental requirements, thereby increasing the likelihood that the permit application
will be approved. 相似文献
945.
The need for accurate carbon budgeting, climate change modelling, and sustainable resource management has lead to an increase
in the number of large area forest monitoring programs. Large area forest monitoring programs often utilize field and remotely
sensed data sources. Sampling, via field or photo plots, enables the collection of data with the desired level of categorical
detail in a timely and efficient manner. When sampling, the aim is to collect representative detailed data enabling the statistical
reporting upon the characteristics of larger areas. As a consequence, approaches for investigating how well sample data represent
larger areas (i.e., the sample neighbourhood and the population) are desired. Presented in this communication is a quantitative
approach for assessing the nature of sampled areas in relation to surrounding areas and the overall population of interest.
Classified Landsat data is converted to forest/non-forest categories to provide a consistent and uniform data set over a 130,000 km2 study region in central British Columbia, Canada. From this larger study area 322 2 × 2 km photo plots on a 20 × 20 km systematic
grid are populated with composition and configuration information for comparison to non-sampled areas. Results indicate that
typically, within the study area, the spatial pattern of forest within a photo plot is representative of the forest patterns
found within primary and secondary neighbourhoods and over the entire population of the study. These methods have implications
for understanding the nature of data used in monitoring programs worldwide. The ability to audit photo and field plot information
promotes an increased understanding of the results developed from sampling and provides tools identifying locations of possible
bias. 相似文献
946.
This study assesses the risk of current-use pesticides in a temporarily open estuary in South Africa by developing probabilistic risk estimates. Particle-associated pesticides (chlorpyrifos, prothiofos, cypermethrin, fenvalerate, endosulfan and p,p-DDE) and physicochemical parameters (salinity, temperature, flow, and total organic content (TOC)) were measured in the Lourens River estuary (Western Cape) twice a month over a period of two years and equilibrium partitioning theory was applied to calculate concentrations of pesticides in the water. The 90th percentile concentrations of pesticides associated to suspended particles and the calculated concentrations in water were 34.0microg kg(-1) and 0.15microg l(-1) for prothiofos, 19.6microg kg(-1) and 0.45microg l(-1) for chlorpyrifos and 18.6microg kg(-1) and 0.16microg l(-1) for endosulfan. Highest average concentrations were found around the summer season due to higher application rates and as a result of the low flow during this season. Species sensitivity distribution indicated a 1.5-2.8 times higher toxicity (hazardous concentration HC5) for marine organisms compared to freshwater organisms. The calculated concentrations in the water exceeded all threshold values suggested by international water guidelines. Chlorpyrifos and endosulfan posed the highest acute risk to the Lourens River estuary. No sufficient toxicity data and threshold values were found for prothiofos. 相似文献
947.
In this work Paspalum notatum root material was used to elucidate the influence of acid leaching pre-treatment and of sorption medium on metal adsorption. Ground P. notatum root was leached with 0.14M HNO(3). Leached root material (LRM) and non-leached root material (NLRM) were employed to flow sorption of Ni(II), Cu(II), Al(III) and Fe(III) in 0.5M CH(3)COONH(4) medium at pH 6.5. For LRM the sorption was also studied in 0.5M KNO(3) medium. The acid pre-treatment increased the sorption capacity (SC) for all ions studied. For the KNO(3) medium, Cu(II) and Fe(III) sorption was higher than in CH(3)COONH(4) and the type of the Ni(II) isotherm's model changed. The Freundlich model was the most representative isotherm model to describe metallic ions sorption. The (1)H NMR spectra showed differences between LRM and NLRM and the acid-basic potentiometric titration elucidated that acid-leaching procedure affected the root material sorption sites once only two predominant sorption sites were found for LRM (phenolic and amine, both able cations sorption) and five sorption sites (two carboxylic, amine and two phenolic) were founded for NLRM. 相似文献
948.
This research focuses on column experiments conducted to evaluate the potential of environmentally compatible rhamnolipid biosurfactant produced by Pseudomonas aeruginosa strain BS2 to remove heavy metals (Cd and Pb) from artificially contaminated soil. Results have shown that di-rhamnolipid removes not only the leachable or available fraction of Cd and Pb but also the bound metals as compared to tap water which removed the mobile fraction only. Washing of contaminated soil with tap water revealed that approximately 2.7% of Cd and 9.8% of Pb in contaminated soil was in freely available or weakly bound forms whereas washing with rhamnolipid removed 92% of Cd and 88% of Pb after 36 h of leaching. This indicated that di-rhamnolipid selectively favours mobilization of metals in the order of Cd>Pb. Biosurfactant specificity observed towards specific metal will help in preferential elution of specific contaminant using di-rhamnolipid. It was further observed that pH of the leachates collected from heavy metal contaminated soil column treated with di-rhamnolipid solution was low (6.60-6.78) as compared to that of leachates from heavy metal contaminated soil column treated with tap water (pH 6.90-7.25), which showed high dissolution of metal species from the contaminated soil and effective leaching of metals with treatment with biosurfactant. The microbial population of the contaminated soil was increased after removal of metals by biosurfactant indicating the decrease of toxicity of metals to soil microflora. This study shows that biosurfactant technology can be an effective and nondestructive method for bioremediation of cadmium and lead contaminated soil. 相似文献
949.
Experiments were carried out to evaluate the use of some agroindustrial wastes as supports in solid state cultures for the biodegradation of crude oil Maya in static column reactors over 15-20 days periods. Spent compost and cane bagasse wastes showed superior qualities over peat moss waste as support candidates with the advantage that they contain appreciable densities of autochthonous microorganisms in the order of 10(2) cfu g(-1). Mercuric chloride (2%) was able to completely inhibit growth of these microfloras. Biodegradation was enhanced in the presence of the IMP consortium and highest when microflora from cane bagasse only was the bioaugmentation partner (180.7 mg kg(-1) day(-1)). Combination of these waste materials (3:1 ratio, respectively) was observed to significantly biodegrade the crude oil by approximately 40% in 15 days from an initial concentration of 10,000 mg kg(-1) with a four order of magnitude increase in microbial density during this period. Spent compost and cane bagasse wastes are veritable solid support candidates for use in the biodegradation of crude oil polluted systems. 相似文献
950.
Matyssek R Bytnerowicz A Karlsson PE Paoletti E Sanz M Schaub M Wieser G 《Environmental pollution (Barking, Essex : 1987)》2007,146(3):587-607
Tropospheric ozone (O3) levels are predicted to stay high, being a factor within "global change" with potential effects on the carbon sink strength of forest trees. Hence, new approaches to O3 risk assessment and their validation are required, although appropriate databases for adult trees are scant. Approaches based on external O3 exposure are presently being evaluated against the ones on O3 flux into leaves, as the cumulative uptake has the capacity for deriving O3 risk from cause-effect relationships. The effective dose, however, needs to account for the trees' O3 defence and tolerance in addition to O3 uptake. The current status of promoting the preferable mechanistic O3 flux concept is highlighted for major regions of Europe, addressing refinements and simplifications needed for routine use. At the pan-European scale, however, the flux-based concept is ready for use in O3 risk assessment and has the potential of meso-scale application at the forest ecosystem level. 相似文献