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951.
In order to assess the quality and suitability of waters in the Kor-Sivand river basin, 60 water samples from the Kor river and 90 water samples from wells in the basin were studied. Assessments were based on Piper's and Gibbs' diagrams for water quality, Food and Agricultural Organization's (FAO) guidelines, and US Salinity Laboratory diagram for water suitability. The results showed that the river water is of Ca-HCO(3) type, while well water is of Ca-Cl and Na-Cl type. Based on Gibbs' diagram, the source of soluble ions in the river water samples is the weathering of stones over which water flows, while evaporation was found to be the dominant process in the ion concentration of the well samples. According to the FAO Guidelines, the salinity of surface water for irrigation did not cause great restrictions; however, many of these waters could create potential permeability problems. In the groundwater samples, a high salt concentration is more important than the infiltration problem. Mg hazard values at some sites limit its use for agricultural purposes. One third of the river water samples and two thirds of well waters had more than 50% magnesium. Saturation indices showed that 94% of the analyzed water samples are supersaturated with calcite, aragonite, and dolomite. Based on the US Salinity Laboratory diagram, river water samples were classified as C(2)S(1) and C(3)S(1), while C(4)S(3), C(4)S(4), C(2)S(1), and C(3)S(1) were the most dominant classes in well samples. Some management practices necessary for sustainable development of water resources in the study area were discussed briefly, including appropriate selection of crops, adequate drainage, leaching, blending and cyclic use of saline water, proper irrigation method, and addition of soil amendment.  相似文献   
952.
In this work, spectrophotometer was used as a detector for the determination of uranium from water, biological, and ore samples with a flow injection system coupled with solid phase extraction. In order to promote the online preconcentration of uranium, a minicolumn packed with XAD-4 resin impregnated with nalidixic acid was utilized. The system operation was based on U(VI) ion retention at pH 6 in the minicolumn at flow rate of 15.2 mL min?1. The uranium complex was removed from the resin by 0.1 mol dm?3 HCl at flow rate of 3.2 mL min?1 and was mixed with arsenazo III solution (0.05 % solution in 0.1 mol dm?3 HCl, 3.2 mL min?1) and driven to flow through cell of spectrophotometer where its absorbance was measured at 651 nm. The influence of chemical (pH and HCl (as eluent and reagent medium) concentration) and flow (sample and eluent flow rate and preconcentration time) parameters that could affect the performance of the system as well as the possible interferents was investigated. At the optimum conditions for 60 s preconcentration time (15.2 mL of sample volume), the method presented a detection limit of 1.1 μg L?1, a relative standard deviation (RSD) of 0.8 % at 100 μg L?1, enrichment factor of 30, and a sample throughput of 42 h?1, whereas for 300 s of the preconcentration time (76 mL of sample volume), a detection limit of 0.22 μg L?1, a RSD of 1.32 % at 10 μg L?1, enrichment factor of 150, and a sampling frequency of 11 h?1 were reported.  相似文献   
953.
Environmental monitoring and indoor radon measurement are important for public health, to estimate the cancer risk of respiratory system and, if necessary, to suggest proper methods that reduce indoor radon level. In this research, indoor radon concentration in the air has been measured in 150 apartments in Mashhad city. The result demonstrates about 94.7% of apartments have radon concentration less than 100 Bq/m3, taken by WHO as the action level, and 5.3% have the concentration higher than this level. As well as, annual radon dose has been assessed using the equation for annual effective dose calculation introduced by United Nations Scientific Committee on the Effects of Atomic Radiation.  相似文献   
954.
In the experiment, mineral contents of the head, caudal, central fleshy part, and spinal columns of fishes were determined by inductively coupled plasma atomic emission spectrometry. The Ca content of base fleshy part ranged from 1,682 to 5,505 mg/kg. The Ca contents of central fleshy part were found between 104 and 428 mg/kg. This value was found between 5,582 and 7,368 in the spinal column parts. The K content in general ranged from 2,411 (Carassius gibellio) and 4,419 mg/kg (Scomber scombrus). The highest potassium was found on the central fleshy part and ranged between 3,214 and 4,419. The P content was found mostly on the bones and it range between 28,833 and 34,726. The least phosphor amount was found on the central fleshy part. While the Cd content ranges between 0.019 ppm and 0.104 mg/kg, Cr content changed between 1.32 and 4.20 ppm.  相似文献   
955.
This paper reports high levels and variability in arsenic (As) levels at locations identified as one of the highest As-contaminated locations in Pakistan. Groundwater pollution related to arsenic has been reported since many years in the areas lying in outskirts of District Lahore, Pakistan. A comparative study is done to determine temporal variations of As from three villages, i.e., Kalalanwala (KLW), Manga Mandi (MM), and Shamki Bhattian (SKB). Seventy-three percent of the 30 investigated samples ranging in depth from 20 to 200 m, show an increasing trend in variations of As concentration over a time span of 4 years and 87 % of samples exceeded the WHO standard of 10 μg/L for As while 77 % of samples have As concentration >50 μg/L (national standard). Further results indicate that high levels of As is accompanied with increase pH (r?=?0.8) favoring desorption of As from minerals at higher pH under oxidizing conditions. For health risk assessment of arsenic, the average daily dose, hazard quotient (HQ), and cancer risk were calculated. The residents of the studied areas had toxic risk index in the order of SKB>KLW>MM, with 87 % of samples exceeding the typical toxic risk index 1.00 (ranging from 2.3–48.6) which was 83 % (ranging from 0.3–41) 4 years before. The results of the present study therefore indicate that arsenic concentrations are increasing in the area, which needs an immediate attention to provide alternate sources of water to save people at risk.  相似文献   
956.
The present study investigated the effects of heavy metals (Ni, Zn, Cd, Cu, and Pb) toxicity on the performance of 18 MLD activated sludge process-based sewage treatment plant (STP) during celebration of Holi (festival of colors in India). The composite sampling (n?=?32) was carried out during the entire study period. The findings show a significant decrease in chemical oxygen demand removal efficiency (20%) of activated sludge system, after receiving the heavy metals laden wastewater. A significant reduction of 40% and 60% were observed in MLVSS/MLSS ratio and specific oxygen uptake rate, which eventually led to a substantial decrease in biomass growth yield (from 0.54 to 0.17). The toxic effect of metals ions was also observed on protozoan population. Out of the 12 mixed liquor species recorded, only two ciliates species of Vorticella and Epistylis exhibited the greater tolerance against heavy metals toxicity. Furthermore, activated sludge shows the highest metal adsorption affinity for Cu, followed by Zn, Pb, Ni, and Cd (Cu?>?Zn?>?Pb?>?Ni?>?Cd). Finally, this study proves the robustness of activated sludge system against the sudden increase in heavy metal toxicity since it recovered the earlier good quality performance within 5?days.  相似文献   
957.
In this paper, a new methodology is developed for integrated allocation of water and waste-loads in river basins utilizing a fuzzy transformation method (FTM). The fuzzy transformation method is used to incorporate the existing uncertainties in model inputs. In the proposed methodology, the FTM, as a simulation model, is utilized in an optimization framework for constructing a fuzzy water and waste-loads allocation model. In addition, economic as well as environmental impacts of water allocation to different water users are considered. For equitable water and waste load allocation, all possible coalition of water users are considered and total benefit of each coalition, which is a fuzzy number, is reallocated to water users who are participating in the coalition. The fuzzy cost savings are reallocated using a fuzzy nucleolus cooperative game and the FTM. As a case study, the Dez River system in south-west of Iran is modeled and analyzed using the methodology developed here. The results show the effectiveness of the methodology in optimal water and waste-loads allocations under uncertainty.  相似文献   
958.
For a Bunter formation in the German Federal State of North Rhine Westphalia, we use numerical models to consider reactions between the supercritical, aqueous, and solid phases. These reactions may occur in a CO2-water system representing a saline aquifer CO2 storage scenario. Thus, the models are used for determining the extent of fluid–rock reactions during mineral dissolution or precipitation. In particular, we study the effect of temperature by comparing results for our system set at 100 °C and at 58 °C. Results show that the abundance of dissolved ions changes as a result of elevated temperature. For the entire 10,000-year simulation period, the overall geochemical behavior of the Bunter reservoir rock at the Minden site is explained in terms of different mineral transformations, although some of them are not changed significantly. This mainly comprises the alteration of carbonate minerals such as calcite, and aluminium silicates such as oligoclase, chlorite, illite, albite, kaolinite, and Na-smectite. Another chemical behavior derives from the generation and consumption of new secondary minerals such as dawsonite, pyrite, and Ca-smectite. In contrast to a system temperature of 58 °C, the mineralogical transformations of other minerals such as siderite, ankerite, dolomite, and magnesite are not observed at 100 °C. Also, the numerical simulation results show that at elevated temperature, the dominant role played by hydrodynamic mechanism dwarfs the role of other trapping mechanisms including dissolution and mineralization. Results also demonstrate how geological, petrophysical, and geochemical data can be integrated to estimate quantitatively the magnitude of the fluid–rock reactions. These reactions may entail new geotechnical problems, such as rock self-fracturing which ultimately decreases the CO2 sequestration projects security.  相似文献   
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