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   230篇
  免费   1篇
安全科学   9篇
废物处理   19篇
环保管理   19篇
综合类   29篇
基础理论   40篇
污染及防治   49篇
评价与监测   61篇
社会与环境   3篇
灾害及防治   2篇
  2023年   5篇
  2022年   7篇
  2021年   4篇
  2020年   1篇
  2019年   2篇
  2018年   4篇
  2017年   6篇
  2016年   9篇
  2015年   8篇
  2014年   26篇
  2013年   44篇
  2012年   5篇
  2011年   5篇
  2010年   13篇
  2009年   12篇
  2008年   11篇
  2007年   9篇
  2006年   12篇
  2005年   8篇
  2004年   1篇
  2003年   4篇
  2002年   3篇
  2001年   3篇
  2000年   5篇
  1999年   1篇
  1998年   3篇
  1997年   1篇
  1995年   4篇
  1987年   1篇
  1985年   1篇
  1982年   1篇
  1981年   2篇
  1979年   1篇
  1977年   1篇
  1976年   1篇
  1974年   1篇
  1964年   1篇
  1960年   1篇
  1943年   1篇
  1942年   1篇
  1937年   1篇
  1936年   1篇
排序方式: 共有231条查询结果,搜索用时 19 毫秒
41.
42.
In the present study, some heavy metals (Cu, Fe, Zn and Mn) were seasonally determined in water, sediment and some tissues of fish Tinca tinca from Bey?ehir Lake, which is an important bird nesting and visiting area, a water source for irrigation and drinking. In the water, Fe has the highest concentrations among the studied metals. Generally, the metal concentrations increased in the hottest period decreased in warm seasons. Results for levels in water were compared with national and international water quality guidelines, as well as literature data reported for the lakes. Fe was the highest in sediment samples, also Cu and Zn were the highest in spring, while Fe and Mn were in autumn. Among the heavy metals studied, Cu and Mn were below the detection limits in some tissues. Generally, higher concentrations of the tested metals were found in the summer and winter, compared with those during the autumn and spring seasons. High levels of heavy metals were found in liver of T. tinca, while low levels in muscle samples. Metal concentrations in the muscle of examined fish were within the safety permissible levels for human consumption. The present study shows that precautions need to be taken in order to prevent further heavy metal pollution.  相似文献   
43.
Delta-aminolevulinate dehydratase (ALAD) activity has been used in prokaryotes and eukaryotes as a biomarker for environmental lead (Pb) exposure and toxicity. Microorganisms are sensitive indicators of toxicity at the fundamental level of ecological organization, but bacterial biomarker studies are focused on the Pseudomonas strains in Group I and E coli. The objectives of the present work were to determine if Burkholderia gladioli belonging to group II, due to its 16SrRNA similarity, can be used as biomarker in metal contamination and compare its possible usage with Pseudomonas aeruginosa and Citrobacter freundii (previously known as Esherichia freundii) and Bacterium freundii which are classified in Group I. In this study, ALAD activity in an environmental strains of Burkholderia gladioli, Pseudomonas aeruginosa, Citrobacter freundii were investigated to evaluate potential inhibition by Pb and other toxic metals. When the ALAD activity of Burkholderia gladioli was tested, Co and Pb decreased activity by 27 and 71%, respectively. In addition to these findings, Zn increased the activity up to 26%. These effects were found to be statistically meaningful (p < 0.05). It was determined that the increase of lead concentration inhibites the ALAD activity at each of the three strains. There was a statistically significant dose–response relationship between ALAD activity in cells of Burkholderia gladioli and Pb (Pearson correlation coefficent = −0.665; r 2 = 0.665, and p < 0.001). The strongest ALAD inhibition which was measured was 90% at Burkholderia gladioli when protein extracts were incubated with 750 μM of Pb. The relationship between Pb and ALAD activity was statistically described by [ALAD Activity] = 0.476−0.000597 × [Pb]. According to the obtained results, we suggest that the ALAD of Burkholderia gladioli can be used as a biomarker for lead contamination in the environment.  相似文献   
44.
The metal accumulation levels for muscle, skin, gill, liver and intestine tissues of some Cyprinidae species (Carassius carassius, Condrostoma nasus, Leuciscus cephalus and Alburnus alburnus) in Enne Dame Lake (Kütahya/Turkey), which is mostly fed by hot spring waters, were investigated. Analyses were performed for copper (Cu), zinc (Zn), manganese (Mn), iron (Fe), cobalt (Co), magnesium (Mg), nickel (Ni), chrome (Cr) and boron (B) using inductively coupled plasma-optic emission spectroscopy (ICP-OES), and cadmium (Cd) using atomic absorption spectrophotometer (AAS) utilizing microwave digestion techniques. The concentrations of the heavy metals found in the fish varied in the follow ing ranges: Cu: < DL-7.04, Zn: 6.96-357.25, Mn: < DL-20.70, Ni: < DL-6.21, Fe: 9.62-2500.33, Cr: < DL-1.74, Co: < DL-0.54, Cd: 0.01-0.27 and Mg: 197.44-904.90 mg/kg wet weight. While B had the second highest concentration in the water of the lake, it was not encountered in any tissue of the investigated species. In all tissues and the species, While the bioaccumulation factors (BAFs) of Mn, Zn, Fe and Cu were remarkably high, the BAFs of Mg, Cr, Co, and B were also fairly low or none. Although the heavy metal accumulation levels for the muscle were generally lower than other tissues, there were some exceptions. Cd level in the muscle of C. carassius was higher than the permissible limit stated by Turkish legislation, FAO and WHO. The mean metal amounts for all the investigated tissues and species are statistically compared and discussed in this study.  相似文献   
45.
Sewage treatment works are one of the major sources that cause atmospheric odour pollution. The increase in the number of complaints about odour nuisance is due to the increase in environmental concerns. Unfortunately, the legislation on odour nuisance from sewage treatment works is very limited. In order to determine suitable thresholds on which to base legal standards, reliable and efficient odour measurement methods need to be defined. A chemical sensor array was developed for the purpose of measuring wastewater odour. This paper describes the development of the chemical sensor system which is specifically tuned to odours of wastewater origin and which can give an electronic measure of the wastewater odours. Odour emissions from a wastewater treatment facility were detected by using a quartz crystal microbalance (QCM) sensor array. The array consists of nine sensor elements, which were coated with different materials. In this paper, the usage of these novel instruments in the water industry was shown.  相似文献   
46.
A mixed-integer programming model that minimizes the social abatement cost is used to investigate whether a market equilibrium condition could be reached in a newly proposed permit-trading market for nitrogen oxide control in Taiwan. Unlike in previous studies, unit pollution abatement cost is determined endogenously by incorporating technology adoption as a binary decision variable. The results show that when technologies are lumpy and irreversible, disequilibrium might occur due to firms’ inability to manage their emission levels after installing equipment with fixed size and control capacity.
Chao-ning LiaoEmail:
  相似文献   
47.
In the present study, a seasonal and non-seasonal prediction of boron concentrations time series data for the period of 1996–2004 from Büyük Menderes river in western Turkey are addressed by means of linear stochastic models. The methodology presented here is to develop adequate linear stochastic models known as autoregressive integrated moving average (ARIMA) and multiplicative seasonal autoregressive integrated moving average (SARIMA) to predict boron content in the Büyük Menderes catchment. Initially, the Box–Whisker plots and Kendall’s tau test are used to identify the trends during the study period. The measurements locations do not show significant overall trend in boron concentrations, though marginal increasing and decreasing trends are observed for certain periods at some locations. ARIMA modeling approach involves the following three steps: model identification, parameter estimation, and diagnostic checking. In the model identification step, considering the autocorrelation function (ACF) and partial autocorrelation function (PACF) results of boron data series, different ARIMA models are identified. The model gives the minimum Akaike information criterion (AIC) is selected as the best-fit model. The parameter estimation step indicates that the estimated model parameters are significantly different from zero. The diagnostic check step is applied to the residuals of the selected ARIMA models and the results indicate that the residuals are independent, normally distributed, and homoscadastic. For the model validation purposes, the predicted results using the best ARIMA models are compared to the observed data. The predicted data show reasonably good agreement with the actual data. The comparison of the mean and variance of 3-year (2002–2004) observed data vs predicted data from the selected best models show that the boron model from ARIMA modeling approaches could be used in a safe manner since the predicted values from these models preserve the basic statistics of observed data in terms of mean. The ARIMA modeling approach is recommended for predicting boron concentration series of a river.  相似文献   
48.
The mineral contents of seed and seed oils of Capparis species growing wild in Turkey were established by inductively coupled plasma–atomic emission spectrometry. Capparis spinosa var. spinosa (2010) and Capparis ovata var. canescens variety (2009) were determined to be rich in terms of mineral matter as 19,514.60 and 16,995.92 ppm as a total, respectively. C. spinosa var. spinosa collected from Mu?la-Milas region (2009) had the highest amount of Ca with 1,010.67 ppm in C. spinosa species and in C. ovata species. C. ovata var. canescens collected from Ankara-Beypazar? (2010) region had the highest amount of Ca with 833.92 ppm Ca amount in C. spinosa var. spinosa, inermis, herbaceae seeds decreased in 2010. C. spinosa var. inermis collected from Antalya-Serik (2010) in C. spinosa species had rich amount of Ca with 123.78 ppm and C. ovata var. palaestina seed oils collected from Mardin-Savur region (2009) had rich amount of Ca with 253.71 ppm in C. ovata species. The oil of C. spinosa var. herbaceae variety collected from Mardin-Midyat region (2010) was determined to have the highest major mineral matter (Ca, K, Mg, Na, and P) with 1,424.37 ppm in C. spinosa species. It was also determined that as a result, caper seed and oils were found to be important sources of nutrients and essential elements.  相似文献   
49.
A thorough investigation of the impact of rainbow trout (Oncorhynchus mykiss) cultivation on surface water quality in the area known as Bereket HES IV Dam Lake was conducted. Water samples were collected from October 2009 to June 2010 from four stations in the Dam Lake and analyzed for water temperature, pH, dissolved oxygen, electrical conductivity, nitrite nitrogen, nitrate nitrogen, and orthophosphate. Surface water quality was then evaluated based on the comparison of samples collected from three stations located near fish cages to those collected from a reference station outside the cultivation area as well as by the comparison with standards specified in the Water Pollution Registration Act. According to the Water Pollution Registration Act, the surface water quality of the Dam Lake was class I. Additionally, there were no significant differences in water quality within the Dam Lake among any of the sampling stations, including the reference station. Overall, these findings indicate that cage cultivation of rainbow trout may have a negative impact on the entire Dam Lake.  相似文献   
50.
The aim of this study was to determine some mineral contents of prickly pear (Opuntia f?cus-indica L.) seeds collected from different locations. The mineral contents of seeds were established by inductively coupled plasma atomic emission spectrometry. All the seeds contained Ca, K, Mg and P at high levels. Calcium content ranged between 268.5 (sample no. 11) and 674.8 ppm (sample no. 4). The level of K changed between 346.7 (sample no. 1) and 676.1 ppm (sample no. 13). Phosphorus content of seeds varied between 1,173.6 (sample no. 14) and 1,871.3 ppm (sample no. 1). It is apparent that seeds are good sources of the macro and micro minerals and can be consumed as a food ingredient to provide nutrition.  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