全文获取类型
收费全文 | 9477篇 |
免费 | 57篇 |
国内免费 | 30篇 |
专业分类
安全科学 | 195篇 |
废物处理 | 444篇 |
环保管理 | 615篇 |
综合类 | 2288篇 |
基础理论 | 2188篇 |
环境理论 | 9篇 |
污染及防治 | 2340篇 |
评价与监测 | 583篇 |
社会与环境 | 869篇 |
灾害及防治 | 33篇 |
出版年
2022年 | 100篇 |
2021年 | 78篇 |
2020年 | 54篇 |
2019年 | 81篇 |
2018年 | 154篇 |
2017年 | 172篇 |
2016年 | 204篇 |
2015年 | 159篇 |
2014年 | 251篇 |
2013年 | 603篇 |
2012年 | 263篇 |
2011年 | 417篇 |
2010年 | 327篇 |
2009年 | 335篇 |
2008年 | 446篇 |
2007年 | 413篇 |
2006年 | 383篇 |
2005年 | 320篇 |
2004年 | 291篇 |
2003年 | 306篇 |
2002年 | 301篇 |
2001年 | 327篇 |
2000年 | 235篇 |
1999年 | 150篇 |
1998年 | 81篇 |
1997年 | 96篇 |
1996年 | 96篇 |
1995年 | 107篇 |
1994年 | 109篇 |
1993年 | 87篇 |
1992年 | 98篇 |
1991年 | 97篇 |
1990年 | 102篇 |
1989年 | 84篇 |
1988年 | 79篇 |
1987年 | 75篇 |
1986年 | 81篇 |
1985年 | 66篇 |
1984年 | 72篇 |
1983年 | 65篇 |
1982年 | 72篇 |
1981年 | 54篇 |
1978年 | 55篇 |
1977年 | 55篇 |
1976年 | 60篇 |
1974年 | 54篇 |
1973年 | 59篇 |
1965年 | 64篇 |
1964年 | 59篇 |
1958年 | 66篇 |
排序方式: 共有9564条查询结果,搜索用时 738 毫秒
71.
The degradation and corresponding product manifold for the pesticide fipronil was determined in three replicate estuarine mesocosms. Aqueous fipronil concentrations rapidly decreased over the 672 h timescale of the experiment (95% removal). Loss was apparently first-order in fipronil, although there appeared to be a change in the removal mechanism after 96 h that corresponded to a dramatic slowdown in its disappearance. The reduction product of fipronil, fipronil sulfide, was not detected in the water column; however, it formed rapidly in sediments and was identified as the major product of fipronil degradation in the system (20% yield at 672 h, with respect to initial fipronil concentration). Fipronil sulfone is thought to form primarily via biological oxidation; and, although it was generated rapidly in the water column (10% yield), only trace amounts were detected in the sediment (1% yield). The direct photolysis product of fipronil, fipronil desulfinyl, was present in all samples; it formed rapidly in the water column (4% yield) and partitioned into the sediment phase (7% yield) over the course of the experiment. The mass balance on fipronil and associated products was 42% at 672 h. 相似文献
72.
Review on the annual PM10 concentrations over a 10-year period shows that Macau is subjected to severe fine particulate pollution. Investigations of its variation in monthly and daily time scales with the local meteorological records reveal further details. It is found that a distinct feature of the Asian monsoon climates, the changes of wind direction, mainly controls the general trend of PM10 concentration in a year. The monsoon driven winter north-easterly winds bring upon Macau dry and particle enriched air masses leading to a higher concentration in that period while the summer south-westerly winds transport humid and cleaner air to the region leading to a lower PM10 value. This distinct seasonal feature is further enhanced by the lower rainfall volume and frequency as well as mixing height in winter and their higher counterparts in summer. It is also found that the development of tropical cyclones near Macau could also impose episode like PM10 concentration spikes due to the pre-typhoon induced stagnant air motion followed by the swing of wind direction to the northerly. 相似文献
73.
Risk-Based Prioritization of Air Pollution Monitoring Using Fuzzy Synthetic Evaluation Technique 总被引:1,自引:0,他引:1
Air pollution monitoring programs aim to monitor pollutants and their probable adverse effects at various locations over concerned area. Either sensitivity of receptors/location or concentration of pollutants is used for prioritizing the monitoring locations. The exposure-based approach prioritizes the monitoring locations based on population density and/or location sensitivity. The hazard-based approach prioritizes the monitoring locations using intensity (concentrations) of air pollutants at various locations. Exposure and hazard-based approaches focus on frequency (probability of occurrence) and potential hazard (consequence of damage), respectively. Adverse effects should be measured only if receptors are exposed to these air pollutants. The existing methods of monitoring location prioritization do not consider both factors (hazard and exposure) at a time. Towards this, a risk-based approach has been proposed which combines both factors: exposure frequency (probability of occurrence/exposure) and potential hazard (consequence).This paper discusses the use of fuzzy synthetic evaluation technique in risk computation and prioritization of air pollution monitoring locations. To demonstrate the application, common air pollutants like CO, NOx, PM10 and SOx are used as hazard parameters. Fuzzy evaluation matrices for hazard parameters are established for different locations in the area. Similarly, fuzzy evaluation matrices for exposure parameters: population density, location and population sensitivity are also developed. Subsequently, fuzzy risk is determined at these locations using fuzzy compositional rules. Finally, these locations are prioritized based on defuzzified risk (crisp value of risk, defined as risk score) and the five most important monitoring locations are identified (out of 35 potential locations). These locations differ from the existing monitoring locations. 相似文献
74.
B. Beck-Friis M. Pell U. Sonesson H. Jönsson H. Kirchmann 《Environmental monitoring and assessment》2000,62(3):317-331
Composting can be a source of N2O andCH4 production. In this investigation, differentcompost heaps of organic household waste weremonitored with the focus on potential formation ofCH4 and N2O in the heaps and emission ofthese gases from the heaps. The studied compost heapshad different compost ages, turning intervals andcompost sizes. The analysed compost gases containedbetween 1–3421 L of N2O-N L-1 and 0–470 mL of CH4 L-1. The emission rates ofN2O and CH4 from the compost heaps werebetween 1–1464 mg N2O m-2 day-1 and0–119 000 mg CH4 m-2 day-1. These verylarge differences in compost gas composition andemission indicate the importance of compostmanagement. The results also give an understanding ofwhere in the composting process an increasing emissionof N2O and CH4 can occur. 相似文献
75.
Fagundez LA Fernández VL Marino TH Martín I Persano DA Rivarola Y Benítez M Sadañiowski IV Codnia J Zalts A 《Environmental monitoring and assessment》2001,71(1):61-70
Passive diffusion samplers were employed in San Miguel(Buenos Aires Metropolitan Area) for a preliminary airpollution monitoring. The highest loads were observedin downtown, compared with an urban background site.Total suspended particulate matter (TSPM) varied from0.257 to 0.033 mg cm-2 month-1; dust was examinedfor particle nature and size distribution. A similartrend was observed for nitrogen dioxide (NO2) andTSPM spatial distribution, suggesting that traffic isthe major pollution source. Sulphur dioxide (SO2)values were low and rather homogeneous. Levels for theinvestigated pollutants are below EPA's guide linevalues. Geographic (flat area, near to Rio de LaPlata) and climatologic factors (rainfalls andvariable wind directions) contribute to disperse pollutants. 相似文献
76.
77.
Leal-Granadillo IA Alonso JI Sanz-Medel A 《Journal of environmental monitoring : JEM》2000,2(3):218-222
A GC-MS procedure for the determination of hydrocarbons in air samples from Oviedo, Spain, was developed. Air hydrocarbons were sampled with a high volume sampler equipped with a holder containing a glass fiber filter, to trap the particulate phase, and two polyurethane foams to capture hydrocarbons of the vapour phase. Compounds were extracted with CH2Cl2 by Soxhlet extraction and then fractionated using column chromatography with alumina silica. Analyses of the fractions were performed by GC-MS in the electron ionization mode. PAHs and n-alkanes were the compounds examined in this work. Samples collected in the vicinity of the Faculty of Chemistry (a semi-urban area) were analysed. The total concentration of PAHs in the air samples analysed ranged from 28 to 76 ng m(-3). The total concentration of n-alkanes and PAHs in the vapour phase exceeded the concentration in the particulate phase in the samples analysed. 相似文献
78.
Shaw I 《Journal of environmental monitoring : JEM》2000,2(2):34N-37N
79.
Indoor and outdoor formaldehyde concentrations in homes in residential areas in Greater Cairo 总被引:1,自引:0,他引:1
Khoder MI Shakour AA Farag SA Abdel Hameed AA 《Journal of environmental monitoring : JEM》2000,2(2):123-126
Indoor and outdoor measurements of formaldehyde were conducted at seven flats located in residential areas in Greater Cairo, during spring and summer seasons 1999. The mean daytime formaldehyde concentrations in kitchens, bedrooms and living rooms were 89, 100 and 100 ppb, respectively, in the seven flats. Significant positive correlations were found between the concentrations of formaldehyde found in these three rooms. On the other hand, no significant differences were found between the mean formaldehyde concentrations in these three rooms. The maximum mean concentration of formaldehyde (147 ppb) was recorded in a new flat, while the minimum concentration (43 ppb) was observed in an old flat. The maximum hourly and daytime concentrations were 350 and 225 ppb, respectively. Air temperature, relative humidity and the age of the flat are factors affecting the emission and concentration of formaldehyde. The maximum indoor and outdoor formaldehyde concentrations were recorded during the summer season. During the spring, 38% of the samples indicated that the concentration of formaldehyde in the seven flats exceeded 0.1 ppm, the American Society of Heating, Refrigerating, and Air Conditioning Engineers' (ASHRAE) standard; in the summer, this figure increased to 53%. 相似文献
80.
Manual and automatic welding machines (which use leaded alloys) are considered to be important sources of the emission of lead fumes into the general air of the working environment. Three workplaces at a television factory were selected for the present study, to determine the control class of the working unit. The concentrations of conventional measurements ("A" sampling points) were lower than the administrative control level (statutory standard of lead, 150 microg m(-3)), whereas the maximum concentration of 264.1 microg m(-3) ("B" sampling point) was higher at one working unit than the administrative control level. However, the control classes varied between class III (bad) and class I (good). 相似文献