首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1987篇
  免费   22篇
  国内免费   30篇
安全科学   80篇
废物处理   137篇
环保管理   180篇
综合类   301篇
基础理论   339篇
污染及防治   663篇
评价与监测   193篇
社会与环境   135篇
灾害及防治   11篇
  2023年   30篇
  2022年   66篇
  2021年   85篇
  2020年   41篇
  2019年   36篇
  2018年   88篇
  2017年   86篇
  2016年   107篇
  2015年   67篇
  2014年   95篇
  2013年   197篇
  2012年   138篇
  2011年   146篇
  2010年   104篇
  2009年   84篇
  2008年   121篇
  2007年   100篇
  2006年   107篇
  2005年   91篇
  2004年   64篇
  2003年   39篇
  2002年   32篇
  2001年   13篇
  2000年   6篇
  1999年   11篇
  1998年   7篇
  1997年   5篇
  1996年   5篇
  1995年   5篇
  1994年   5篇
  1993年   2篇
  1992年   2篇
  1991年   4篇
  1990年   4篇
  1988年   5篇
  1987年   2篇
  1986年   3篇
  1985年   3篇
  1984年   2篇
  1983年   2篇
  1979年   2篇
  1966年   2篇
  1962年   2篇
  1961年   2篇
  1960年   2篇
  1959年   2篇
  1953年   2篇
  1930年   1篇
  1929年   1篇
  1928年   2篇
排序方式: 共有2039条查询结果,搜索用时 265 毫秒
101.
Pinna nobilis is a large bivalve, endemic to the Mediterranean Sea that was shown in a previous study to ingest significantly different proportions of different food items according to its shell height. Fatty acid profiling of total lipids was used to examine these differences in diet in relation to shell size. Small (shell height 23.0 ± 3.3 cm), medium (SH 41.5 ± 5.5 cm) and large (SH 62.7 ± 4.8 cm) P. nobilis were collected from Mali Ston Bay, Adriatic Sea, in March 2010, and fatty acid analysis was performed on digestive gland and adductor muscle tissues. Based on the analysis of the digestive gland, small P. nobilis were associated with a detrital food chain, characterized by saturated and branched-chain fatty acids, while the diets of medium and large individuals had a greater proportion of polyunsaturated fatty acids. This likely reflects the fact that smaller individuals feed within the benthic boundary layer where the detritus concentrations are high. Fatty acid incorporation into the adductor muscle, likely representative of food taken up over a longer time period, was reversed, that is, larger individuals had lower levels of polyunsaturated fatty acids. This most probably reflects energy expenditure, which typically increases with increasing organism size.  相似文献   
102.
A future business-as-usual scenario (A1FI) was tested on two bloom-forming cyanobacteria of the Baltic Proper, Nodularia spumigena and Aphanizomenon sp., growing separately and together. The projected scenario was tested in two laboratory experiments where (a) interactive effects of increased temperature and decreased salinity and (b) interactive effects of increased temperature and elevated levels of pCO2 were tested. Increased temperature, from 12 to 16 °C, had a positive effect on the biovolume and photosynthetic activity (F v/F m) of both species. Compared when growing separately, the biovolume of each species was lower when grown together. Decreased salinity, from 7 to 4, and elevated levels of pCO2, from 380 to 960 ppm, had no effect on the biovolume, but on F v/F m of N. spumigena with higher F v/F m in salinity 7. Our results suggest that the projected A1FI scenario might be beneficial for the two species dominating the extensive summer blooms in the Baltic Proper. However, our results further stress the importance of studying interactions between species.  相似文献   
103.
The inadequate and indiscriminate disposal of sugarcane vinasse in soils and water bodies has received much attention since decades ago, due to environmental problems associated to this practice. Vinasse is the final by-product of the biomass distillation, mainly for the production of ethanol, from sugar crops (beet and sugarcane), starch crops (corn, wheat, rice, and cassava), or cellulosic material (harvesting crop residues, sugarcane bagasse, and wood). Because of the large quantities of vinasse produced, alternative treatments and uses have been developed, such as recycling of vinasse in fermentation, fertirrigation, concentration by evaporation, and yeast and energy production. This review was aimed at examining the available data on the subject as a contribution to update the information on sugarcane vinasse, from its characteristics and chemical composition to alternatives uses in Brazil: fertirrigation, concentration by evaporation, energy production; the effects on soil physical, chemical and biological properties; its influence on seed germination, its use as biostimulant and environmental contaminant. The low pH, electric conductivity, and chemical elements present in sugarcane vinasse may cause changes in the chemical and physical–chemical properties of soils, rivers, and lakes with frequent discharges over a long period of time, and also have adverse effects on agricultural soils and biota in general. Thus, new studies and green methods need to be developed aiming at sugarcane vinasse recycling and disposal.  相似文献   
104.
Chitosan (a biopolymer) is an aminopolysaccharide that can be used for the treatment of colored solutions by coagulation–flocculation (as an alternative to more conventional processes such as sorption). Acid Blue 92 (a sulfonic dye) was selected as a model dye for verifying chitosan's ability to treat textile wastewater. A preliminary experiment demonstrated that chitosan was more efficient at color removal in tap water than in demineralized water, and that a substantially lower concentration of chitosan could be used with tap water. Dye removal reached up to 99% under optimum concentration; i.e., in terms of the acidic solutions and the stoichiometric ratio between the amine groups of the biopolymer and the sulfonic groups in the dye. The flocs were recovered and the dye was efficiently removed using alkaline solutions (0.001–1 M NaOH solutions) and the biopolymer, re-dissolved in acetic acid solution, was reused in a further treatment cycle.  相似文献   
105.
Loss of temperature control is one of the major reasons that can lead to runaway reaction. This occurrence is commonly named thermal runway. The aim of this paper is the application of thermal runaway criteria in order to predict the onset of runaway phenomena and define the range of stability related to operating conditions in the reactor, with specific reference to the esterification of acetic anhydride and methanol catalysed by sulphuric acid tested in isoperibolic conditions. The isoperibolic calorimeter has also been used to obtain thermodynamic, kinetic and physical chemistry data necessary to develop a model for the reaction. Some runaway criteria applied in this work require a model for the process, so a model for the analyzed system been developed.Because of the modest reaction enthalpy and low activation energy this reacting system provide a severe test to the runaway criteria.In this work, various runaway criteria have been applied to the experimental and simulated data and the results obtained have been compared.  相似文献   
106.
107.
Poultry litter generated on the Delmarva Peninsula is from phytase-modified bird diet and bisulfate amendment. To establish agronomic application rates in conservation tillage systems, bisulfate-amended phytase-diet poultry litter was investigated for its nutrient release kinetics and supply capacity under simulated weathering conditions. Delmarva poultry litter was packed in PVC columns (15 cm i.d. × 25 cm height) to a depth of 5 cm and leached intermittently with 600 mm of water for 190 days. Concentrations of various nutrients in leachate were analyzed and nutrient release kinetics were modelled. Poultry litter leachate contained high contents of dissolved organic carbon (DOC, 35–11,800 mg L?1), nitrogen (N 6–2690 mg L?1), phosphorus (P 45–225 mg L?1), potassium (K 20–6060 mg L?1), and other nutrients. Release of the nutrients occurred primarily in the starting 5 weeks and mostly followed a first order Exponential-Rise-to-Maximum model. Under the specified conditions, the poultry litter demonstrated a nutrient supply capacity of 11.7 kg N Mg?1, 5.4 kg P Mg?1, and 36.8 kg K Mg?1. Release of the potentially plant-available N and K was nearly finalized within 190 days of leaching/weathering, but it would require two years for full release of the leachable P. The results indicate that with consideration of field conditions, surface application of bisulfate-amended phytase-diet Delmarva poultry litter at recommended 6.6 Mg ha?1 to conservation tillage systems would largely provide P 25.0 kg ha?1, N 106.6 kg ha?1, and K 245.5 kg ha?1 to seasonal crops.  相似文献   
108.
ABSTRACT

The present work was designed to determine the potential genotoxicity at the vicinity of a solid waste incinerator in the metropolitan area of Sâo Paulo, using the Tradescantia stamen-hair bioassay. Experiments were carried out between December 1998 and April 1999 in four regions (40 pots of plants per site) selected on the basis of their pollution levels predicted by theoretical modeling of the dispersion of the incinerator's plume. The exposure sites were defined as follows: highest level (incinerator); a high level (museum) located 1.5 km from the emission point; a moderate level (school, at a distance of 3.5 km from the incinerator); and a control (at Jaguariuna countryside). The difference in genotoxicity among the groups was statistically significant (p < 0.001). The frequency of mutations observed in the countryside was significantly lower [2.25 ± 1.55, mean ± SD (standard deviation)] than that of the sites close to the incinerator. The frequency of mutations measured at the school (3.70 ± 1.36) was significantly lower than that measured at both the museum (4.89 ± 1.12) and the incinerator (5.69 ± 1.34). In conclusion, we found a positive correlation between the spatial distribution of the emissions of the incinerator located in an urban area and the mutagenic events measured by the Tradescantia stamen-hair assay. The in situ approach employed in this study was simple, efficient, and of low cost. No air or chemical extraction of pollutants was necessary for genotoxicity testing as required by other assays.  相似文献   
109.
In the last years pharmaceuticals have aroused great interest as environmental pollutants for their toxic effects towards non target organisms. This study wants to draw attention to a further adverse effect of drugs, the endocrine interference. The most representative drugs of the widespread classes in environment were investigated. The YES-test and the E-screen assay were performed to detect the capability of these substances to bind the human estrogenic receptor α (hERα) in comparison with 17β-estradiol. Out of 14 tested pharmaceuticals, 9 were positive to YES-assay and 11 were positive to E-screen assay; in particular, Furosemide and the fibrates (Bezafibrate, Fenofibrate and Gemfibrozil) gave the maximal estrogenic response. Tamoxifen showed its dual activity as agonist and antagonist of hERα.  相似文献   
110.
Solid waste management (SWM) is one of the most challenging issues faced by developing countries that suffer from serious pollution problems caused by the generation of large waste quantities. This paper presents the case study of SWM in the Nablus district – Palestine. Surveys for household residents' and SWM program operators, field investigations, on-site waste measurements and characterizations were conducted. Per capita waste generation rates varied between different localities although trends were similar. Overall, the majority of waste was organic (65.1% by weight), suggesting a strong resource recovery potential in terms of animal feed or compost. Recyclable waste (plastic, paper and card) made up 16.7% by weight the waste composition suggesting an incentive to introduce source separation. Household attitudes complemented the waste characterization study, revealing the main problems faced. SWM operators quoted on the current status, highlighting problems with disposing in unsanitary landfills, ineffective solid waste fees system, increasing solid waste quantities and lacking equipment and experienced personnel. To enhance sustainable SWM, public awareness, funding, expertise, equipment and facilities and other provisions currently lacking or inappropriate must be provided.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号