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531.
The maximum likelihood (ML) method for regression analyzes of censored data (below detection limit) for nonlinear models is presented. The proposed ML method has been translated into an equivalent least squares method (ML-LS). A two stage iterative algorithm is proposed to estimate statistical parameters from the derived least squares translation. The developed algorithm is applied to a nonlinear model for prediction of ambient air CO concentration in terms of concentrations of respirable particulate matter (RSPM) and NO2. It has been shown that if censored data are ignored or estimated through simplifications such as (i) censored data are equal to detection limit, (ii) censored data are half of the difference between detection limit and lower limit (e.g., zero or background level) or (iii) censored data are equal to lower limit, this can cause significant bias in estimated parameters. The developed ML-LS method provided better estimates of parameters than any of the simplifications in censored data. 相似文献
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Vikrant Jaryan Sanjay Kr. Uniyal Gopichand R. D. Singh Brij Lal Amit Kumar Varun Sharma 《The Environmentalist》2010,30(2):101-110
Recognizing the importance of sacred groves in biodiversity conservation and management, and the recent threats to them, the
present study was conducted in Shivbari sacred grove of Himachal Pradesh. The study aimed at documenting the floral wealth
of Shivbari and promoting plantation of indigenous species in participation with local people. For this, systematic field
surveys in different seasons were conducted in Shivbari from April 2005 to November 2009, and liaison was maintained with
the local community and temple management authority for gaining insight into the history and problems of Shivbari and initiating
plantation activities. A total of 69 flowering plant species were identified inside the grove, which include 14 trees, 9 shrubs,
3 lianas and 43 herbs. This represents almost 2% of the total flowering plant species occurring in the state of Himachal Pradesh.
Mallotus philippensis followed by Putranjiva roxburghii was the most dominant tree species. Adhatoda
zeylanica was the most common shrub species, while Achyranthes aspera was the most common herb species. The grove harbours 23 plants species that are in high demand in the market, and at the
same time also influences the microclimate of the area. The temperature inside the grove was significantly lower than the
temperature outside the grove. The recent changes in socio-economic status of the local people and a shift towards market-oriented
economy have threatened the survival of Shivbari. However, the deeply held beliefs of the pilgrims, local people and priest
offer a ray of hope. During the course of the study, 3,000 plants were planted inside the grove out of which 60% have survived. 相似文献
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Gupta N Sharma RC Tripathi AK 《Journal of environmental biology / Academy of Environmental Biology, India》2008,29(3):381-386
Aquatic biodiversity is one of the most essential characteristics of the aquatic ecosystem formaintaining its stability and a means of coping with any environmental change. The entire stretch of the Mothronwala swamp has rich riparian vegetation for providing conducive environment for the growth of aquatic organisms. The present work has been undertaken to study the bio-physico-chemical characteristics of the swamp. The data on physico-chemical environmental variables (temperature, total dissolved solutes, size and composition of substratum, pH, dissolved oxygen, alkalinity chlorides, and hardness) have been given under the present contribution. A total of 16 genera of aquatic insects belonging to orders Trichoptera, Coleoptera, Hemiptera, Ephemeroptera, Odonata and Phylum Mollusca represented the macroinvertebrates of Mothronwala swamp. The fresh water swamp of Mothronwala is under threat due to human interference and other anthropogenic activities. Some of the natural and anthropogenic environmental problems of the Mothronwala swamp have been identified and the ameliorative measures for the protection of aquatic environment and the conservation measures for the swamp have been suggested. The qualitative study revealed the present status of the aquatic biodiversity of the swamp and also about the physico-chemical parameters, which would be very helpful for policy makers to take precautionary measures to save the swamp. 相似文献
538.
Pollution level in distillery effluent and its phytotoxic effect on seed germination and early growth of maize and rice 总被引:1,自引:0,他引:1
Pandey SN Nautiyal BD Sharma CP 《Journal of environmental biology / Academy of Environmental Biology, India》2008,29(2):267-270
The effluent from a Lucknow- based distillery (Mohan Meakin Distillery) was analyzed for physico-chemical and biological parameters of pollution and concentration of potentially toxic heavy metals (Cd, Cr, Ni and Zn) and the effect of the distillery effluent, as such and on 50% dilution with tap water was studied on seed germination and seedling growth of maize (Zea mays L.) and rice (Oryza sativa L.). The effluent was wine red in colour and highly acidic (pH approximately 55) and possessed decaying alcoholic smell. The effluent contained high values of different pollution parameters, particularly total solids, 3450 mgl(-1) (soluble plus suspended solids), alkalinity 1500 mgl(-1), biological oxygen demand (BOD, 1649 mgl(-1)) and chemical oxygen demand (COD, 2036 mgl(-1)). It had very low values of dissolved oxygen (DO, 0.34 mgl(-1)). The heavy metals (Cd, Cr, Ni and Zn) content, particularly the nickel concentration (0.029 mg l(-1)) was high. Use of the distillery effluent, even on 1:1 dilution with tap water inhibited germination and early seedling growth of maize and rice. In both maize and rice, more so in the former germination % of seeds, length of radicle and plumule and the fresh and dry weight of the seedlings were significantly reduced. The emerging leaves of the seedlings also developed visible effects of toxicity some of which resembled the symptoms of nickel toxicity. Our observations suggest that the effluent, as discharged from the distillery carry a heavy load of pollutants. Its discharge into the river Gomti poses a potential threat to the aquatic life, perticularly during the summer months when the water flow in the river is drastically reduced. The distillery effluentis also harmful for irrigating crops grown along the drain carrying it. 相似文献
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In the present study different doses (0.05, 2.0 and 5.0?mg per 30?ml nutrient medium) of nano-powder (Azadirachta indica leaves) were applied in Cd contaminated (6?ppm) hydroponic system to regulate the metal uptake in Triticum aestivum (wheat) seedlings. Other physiological attributes including oxidative biomarkers, antioxidants and photosynthetic responses were also assessed. The level of Cd was maximally reduced at the dose of 2.0?mg nano powder per 30?ml nutrient medium by 45 and 49% in the shoot and root, respectively. With the maximum reduction in the Cd uptake at this dose, the generation of oxidative stress markers such as H2O2 (12%), MDA (26%) and SOR (20%) content showed maximum reduction in treated seedlings. At different doses of nano-powder, the activities of antioxidative enzymes were also showed significant variation. Further, the photosynthetic O2 evolution rate was improved with the treatment of nano-powder and the best response was noted at 2.0?mg per 30?ml nutrient medium with the maximum value of fresh shoot biomass (38%). The overall results suggest that, this technique could be easily applied for reducing the metal content and increasing the quality of agricultural crops. 相似文献