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291.
The suitability of a 0.5 M HCl solution for extraction of Fe, Mn, Cd, Co, Cu, Pb, and Zn from Nile River sediments was evaluated by comparing its effectiveness with that of conventional acid ammonium oxalate (Tamm's solution) and aqua regia extraction solutions. The present study has shown that although the extraction data indicate that both 0.5 M HCl and acid ammonium oxalate solutions are able to extract heavy metals simultaneously from the adsorbed, organic, and precipitated phases of Nile sediments, the 0.5 M HCl solution is preferred. It provides a rapid, reliable, and inexpensive method of measuring environmentally mobile metal concentrations in the aquatic sediments. From an analytical chemistry point of view, the 0.5 M HCl extracts do not clog the atomizer of the spectrophotometer. Extraction with dilute HCl solution obviates the need to use chemicals, some of which are toxic or not available readily as a high-purity grade. A standard extraction method should be relatively simple, to conduct a routine analysis of large numbers of sediment samples, yet at the same time it should provide sufficient information for assessment of the environmental impact of particulate metals. Therefore, extraction with 0.5 M HCl solution is very suitable for heavy-metal pollution monitoring in the Nile River 相似文献
292.
Mohammed Rasheed Christian Wild Carin Jantzen Mohammed Badran 《Chemistry and Ecology》2006,22(1):13-20
In situ and laboratory incubation experiments in a fringing reef in the Gulf of Aqaba were performed to study degradation rates of particulate organic matter in reef sediments. Coral mucus, clam eggs, and zooxanthellae were used as model particulate organic compounds for these experiments. Aerobic and anaerobic mineralization rates were calculated by dissolved inorganic carbon (DIC) and O2 fluxes from the sediments under different particulate organic matter additions. Fast enhancement (approximately twofold) of O2 and DIC fluxes were found with the addition of coral mucus and clam eggs compared with control incubations without addition. Most of the degradation is believed to have occurred anaerobically rather than aerobically (DIC:O2 ratios were 4.3-28.1). Higher degradation rates of coral mucus and clam eggs were estimated in carbonate sediment than in silicate sediment (1.2-1.6-fold), which was attributed to the different physical and chemical properties of both sediments. Our study shows the significance of the reef sediment as a suitable site for microbial degradation of particulate organic material excreted from different reef community organisms. This may increase the regeneration of nutrients in the reef environment necessary to sustain high biological productivity. 相似文献
293.
294.
为了解祊河河流沉积物重金属情况,以祊河橡胶坝至沂蒙路大桥段为主研究对象,对河段内8个断面沉积物的3个指标(Cu、Zn、Cd)进行监测调查,参照国内有关标准,建立了适合该区域的沉积物污染评价标准,主要运用潜在生态危害指数法和内梅罗法标准指数法对检测结果进行生态风险和污染程度评价。结果表明:祊河橡胶坝至沂蒙路大桥段沉积物重金属生态危害指数高达3418.5,内梅罗污染指数为6.95,为重度污染,说明祊河沉积物重金属污染非常严重。 相似文献
295.
296.
Characteristics of heavy metals and Pb isotopic signatures in sediment cores collected from typical urban shallow lakes in Nanjing, China 总被引:2,自引:0,他引:2
To investigate the contamination levels and sources for heavy metals that have occurred during the development of cities, sediment cores collected from typical urban shallow lakes (Xuanwu Lake and Mochou Lake) in Nanjing, China were analyzed for Cu, Pb, Zn, Cd, Cr, Ni, and for Pb stable isotopic ratios. No significant differences were found in the concentrations of Cu, Ni and Cd among sediment layers from Xuanwu or in the levels of Cr and Ni among sediment layers from Mochou. However, there were significant differences among the layers in the concentrations of Cr, Zn and Pb in Xuanwu and Cu, Zn, Cd and Pb in Mochou. Based on geoaccumulation indexes and enrichment factors, Cd was the primary pollutant at all depths in the sediment cores. The ratios of (206)Pb/(207)Pb and (208)Pb/(206)Pb differ significantly among sediment layers in Xuanwu. No significant differences were found on the ratios of (208)Pb/(206)Pb in Mochou, but the ratios of (206)Pb/(207)Pb differ significantly among some of the sediment layers in Mochou. The range of (208)Pb/(206)Pb and (206)Pb/(207)Pb ratios was found to be 2.098-2.106 and 1.170-1.176, respectively, for sediment cores from Mochou Lake and 2.091-2.104 and 1.168-1.183, respectively, for cores from Xuanwu Lake. The differences in heavy metal concentrations and the Pb isotopic ratios with depth for the cores from Xuanwu and Mochou confirmed that the contamination sources changed during the formation of the different sediment layers. Furthermore, the ratios of (206)Pb/(207)Pb demonstrated that gasoline and vehicular Pb were not the primary sources of Pb contamination at different depths in the sediment cores in Xuanwu Lake and Mochou Lake. 相似文献
297.
Role of buffer strips in management of waterway pollution: A review 总被引:11,自引:0,他引:11
A buffer strip can perform a multitude of functions, and these include channel stability, a filter for sediment and nutrients,
water purification (e.g., bacteria and pathogens), a nondisturbance area, and the provision of terrestrial and stream habitat.
These functions are reviewed with specific application to Australian conditions, and methods for modeling their performance
are outlined. The primary focus is on the use of buffer strips to minimize waterway pollution from diffuse sources since their
use is often justified on this basis. Particular attention is given to the conditions under which a buffer strip will act
as an effective filter and the conditions under which it will fail. Buffer strips are most effective when the flow is shallow
(nonsubmerged), slow, and enters the buffer strip uniformly along its length. Their sediment trapping performance decreases
as the sediment particle size decreases. Nutrients are often preferentially attached to fine sediment. As a result, buffer
strips are better filters of sediment than of nutrients. Buffer strips should only be considered as a secondary conservation
practice after controlling the generation of pollutants at their source and, to be effective, buffer strips should always
be carefully designed, installed, and maintained. 相似文献
298.
Organic matter (OM) is an important component of sediment. Bioturbation/bioirrigation can remobilize OM and heavy metals that were previously buried in the sediment. The remobilization of buried organic matter, thallium (Tl), cadmium (Cd), copper (Cu) and zinc (Zn) from sediment was studied in a laboratory experiment with three organisms: tubificid, chironomid larvae and loach. Results showed that bioturbation/bioirrigation promoted the release of dissolved organic matter (DOM) and dissolved Tl, Cd, Cu and Zn, but only dissolved Zn concentrations decreased with exposure time in overlying water. The presence of organisms altered the compositions of DOM released from sediment, considerably increasing the percentage of fulvic acid-like materials (FA) and humic acid-like materials (HA). In addition, bioturbation/bioirrigation accelerated the growth and reproduction of bacteria to enhance the proportion of soluble microbial byproduct-like materials (SMP). The DOM was divided into five regions in the three-dimensional excitation emission matrix (3D-EEM), and each part had different correlation with the dissolved heavy metal concentrations. Dissolved Cu had the best correlation with each of the DOM compositions, indicating that Cu in the sediment was in the organic-bound form. Furthermore, the organism type and heavy metal characteristics both played a role in influencing the remobilization of heavy metal. 相似文献
299.
The condition of Baiyangdian Lake(BYDL) will improve as the Xiongan New Area evolves and fulfills its role of easing overcrowding and supporting economic growth. Water and sediment samples from BYDL were analyzed to provide information on nitrogen(N) contamination in BYDL. The mean ammonium N(NH_4~+-N), nitrate N, and total N concentrations in the water samples were 0.36, 0.12, and 2.22 mg/L, respectively, and the ranges were 0.003–8.38, 0.06–0.30,and 1.25–10.34 mg/L, respectively. The N concentrations in water gradually increased from the north to the south of BYDL. Sediment at 90% of the sampling sites was in or above the moderately contaminated class(1000–2000 mg/kg) defined in US Environmental Protection Agency total N pollution standards. Positive NH_4~+-N fluxes were found for 28 of the 34 sediment core samples, so the potential for NH_4~+-N being released from sediment was relatively high. The NH_4~+-N fluxes were 5.35–48.76 mg/m~2/day, and the mean and maximum fluxes were 8.71 and 48.76 mg/m~2/day, respectively. Benthic organisms will be affected more by NH_4~+-N and NH_3·H_2O in the surface sediment pore water(mean concentrations 4.93 and 0.13 mg/L, respectively) than by the other forms of N. 相似文献
300.
Changchun Huang Yixin Bai Kunlin Shi Heyu Yu Nana Shang Weiyue Hao Chuan Wang Tao Huang Hao Yang 《环境科学学报(英文版)》2022,34(11):224-233
Receptor models are a useful tool for identifying sources of polycyclic aromatic hydrocarbons (PAHs) in multiple environmental media. In this study, three different receptor models (including the principal component analysis-multiple linear regression (PCA-MLR), positive matrix factorization (PMF), and Unmix models) were used to apportion the sources of 16 priority PAHs in a sediment core of Lake Dagze Co. The ∑PAHs (sum of all 16 measured PAHs) concentrations ranged from 51.89 to 132.82 ng/g with an average of 80.39 ng/g. The ∑PAHs were dominated by 2-3 ring PAHs, accounting for 80.12% on average, thereby indicating that they mainly originated from biomass and coal combustion and/or from long-range atmospheric transportation. The three models produced consistent source apportionment results. The greatest contributor to ∑PAHs was biomass combustion, followed by coal combustion, vehicle emissions, and petrogenic sources. Moreover, the temporal variation of the common sources was well-correlated among models. The multi-method comparison and evaluation results showed that all three models were useful tools for source apportionment of PAHs, with the PMF model providing better results than the PCA-MLR and Unmix models. The temporal trends of factor contributions were verified by PAHs with different ring numbers. Significant correlations were found between the simulated concentrations of each source factor and the PAHs with different ring numbers (P<0.01), except for the petrogenic source identified by the Unmix model (P>0.05). This study can provide useful information for further investigation of source apportionment of PAHs in the sediment cores. 相似文献