全文获取类型
收费全文 | 1189篇 |
免费 | 139篇 |
国内免费 | 386篇 |
专业分类
安全科学 | 81篇 |
废物处理 | 170篇 |
环保管理 | 127篇 |
综合类 | 822篇 |
基础理论 | 150篇 |
污染及防治 | 242篇 |
评价与监测 | 81篇 |
社会与环境 | 26篇 |
灾害及防治 | 15篇 |
出版年
2024年 | 2篇 |
2023年 | 24篇 |
2022年 | 36篇 |
2021年 | 46篇 |
2020年 | 34篇 |
2019年 | 42篇 |
2018年 | 52篇 |
2017年 | 47篇 |
2016年 | 51篇 |
2015年 | 64篇 |
2014年 | 57篇 |
2013年 | 70篇 |
2012年 | 64篇 |
2011年 | 107篇 |
2010年 | 86篇 |
2009年 | 86篇 |
2008年 | 81篇 |
2007年 | 90篇 |
2006年 | 80篇 |
2005年 | 76篇 |
2004年 | 62篇 |
2003年 | 50篇 |
2002年 | 54篇 |
2001年 | 70篇 |
2000年 | 47篇 |
1999年 | 42篇 |
1998年 | 32篇 |
1997年 | 40篇 |
1996年 | 30篇 |
1995年 | 18篇 |
1994年 | 11篇 |
1993年 | 11篇 |
1992年 | 13篇 |
1991年 | 12篇 |
1990年 | 7篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1975年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有1714条查询结果,搜索用时 271 毫秒
471.
以马尾松为指示植物,对韶关的土壤进行了长期淋溶模拟并记录其化学状态。结果发现,土壤溶液的pH值下降到4.0,Bs值下降到几乎为零,有较大量的A1离子溶出。最后选取土壤溶液pn〉4.0、KS〉10%和[Al^3+]〈0.1mmol/L为临界化学指标,参考国内外应用广泛的MAGIC模型和SMART模型,确定韶关酸沉降临界负荷(S的临界负荷)为14.1keq/hm^2.a。 相似文献
472.
473.
Guor-Cheng Fang Hung-Che Chiang Yu-Cheng Chen You-Fu Xiao Yuan-Jie Zhuang 《Environmental Forensics》2014,15(4):296-305
This study characterized the dry deposition flux and dry deposition velocity (Vd) of metallic elements attached on particulate matter. Specifically, large particles (>10 μm), coarse particles (10 μm~2.5 μm), and fine particles (<2.5 μm) were studied at the Gong Ming Junior High School (Taichung Airport) and Taichung Harbor sampling sites in central Taiwan. Ambient air samples were collected to determine total suspended particulate matter (TSP), dry deposition plate (DDP), Vd, coarse particulate matter (PM2.5–10) and fine particulate matter (PM2.5), and metallic elements concentrations at the Airport and Taichung Harbor sites between June 17, 2013, and November 14, 2013. The results revealed that the average TSP, DDP, Vd, PM2.5–10, and PM2.5 particulate at the Airport were 54.55 (μg/m3), 902.25 (μg/m2-min), 17.11 (m/sec), 0.003 (μg/m3), and 0.010 (μg/m3), respectively; while these values at Taichung Harbor were 63.66 (μg/m3), 539.69 (μg/m2-min), 9.94 (m/sec), 0.003 (μg/m3), and 0.014 (μg/m3), respectively. In addition, the results showed that the average Cu and Pb concentrations were higher than Cr, Ni, and Cd for both the airport and harbor sampling sites. Furthermore, Cr, N, Cu, Cd, and Pb had the highest average concentrations versus those reported for other study areas, with one exception: The results obtained in Kacanik, Kosovo, during 2005. The average metallic elements concentrations order was Cu > Pb > Cr > Ni > Cd. 相似文献
474.
湿磨系统在湿法脱硫中应用非常广泛,但也存在不少问题。分析了湿式球磨机运行电流下降、系统堵塞等堵磨现象产生的原因,探讨了湿磨系统堵磨后的处理方法。采取针对性的检修及运行措施,形成一套完整的方案,可以预防湿式球磨机堵磨事件发生,为湿式球磨机堵磨处理及预防提供了参考。 相似文献
475.
Rainwater samples were collected from Tamale town in the 1997 and 1998 rainy seasons. During this period road construction in the Tamale area resulted in the generation of suspended dust in the atmosphere. Analysis of the samples for major ions showed elevated levels of Cl–. Ion ratios with Cl– (Na+/Cl–, K+/Cl–, Ca2+/Cl–/Cl– Mg2+/Cl– and SO4
2–/Cl–) in rainwater samples were higher than the corresponding ratios in seawater. Some samples also showed elevated concentrations of Fe, Mn, Al and Zn, all of which except Zn showed a correlation with the dry periods between rainfall events. Consequently, it was concluded that dust generated from lateritic soils was probably the major cause of the increase in concentration of these metals. Aluminium and Fe concentrations were observed to be higher than the World Health Organization drinking water guide limits. 相似文献
476.
Evaluating Controlling Factors to Ali/(Ca + Mg) Molar Ratio in Acidic Soil Water, Southern and Southwestern China: Multivariate Approach 总被引:2,自引:0,他引:2
Guo JH Zhang XS Vogt RD Xiao JS Zhao DW Xiang RJ Luo JH 《Environmental monitoring and assessment》2007,129(1-3):321-329
Ali/(Ca + Mg) molar ratio in soil water has been used as an indicator to the effects of acid deposition on terrestrial ecosystems.
However, the main factors controlling this ratio have not been well documented in southern and southwestern China. In this
study, we presented the variation in inorganic aluminum (Ali) and Ali/(Ca + Mg) molar ratio in different sites and soil horizons based on two to three years monitoring data, and evaluated the
main factors controlling Ali/(Ca + Mg) molar ratio using principle component analysis (PCA) and partial least square (PLS) regression. Monitoring data
showed although Ali/(Ca + Mg) molar ratios in most soil water were lower than assumed critical 1.0, higher molar ratios were found in some soil
water at TSP and LXH site. Besides acid loading, both soil properties and soil water chemistry affected the value of Ali/(Ca + Mg) molar ratio in soil water. Partial least square (PLS) indicated that they had different relative importance in
different soil horizons. In A-horizon, soil aluminum saturation (AlS) had higher influence on Ali/(Ca + Mg) molar ratio than soil water chemistry did; higher soil aluminum saturation (AlS) led to higher Ali/(Ca + Mg) molar ratio in soil water. In the deeper horizons (i.e., B1-, B2- and BC-horizon), inorganic aluminum (Ali) in soil water had more and more important role in regulating Ali/(Ca + Mg) molar ratio. On regional scale, soil aluminum saturation (AlS) as well as cation exchange capacity (CEC) was the
dominant factor controlling Ali/(Ca + Mg) molar ratio. This should be paid enough attention on when making regional acid rain control policy in China. 相似文献
477.
Background, Aim and Scope
Acid deposition has become a concern in south China in recent years. This phenomenon has increased to a dramatic extent with
the large use of cars and coal- fueled power plants. As a consequence, soils are becoming acidified and their element dynamics
will change. A decrease in the nutrient availability will lead to slower plant growth and maybe to a change in the forest
type with current species being replaced by new ones with less nutrient requirements. Because of these reasons, it is important
to understand how the dynamics of elements will change and what mechanism is part of the process. This knowledge is important
for modeling the acidification process and either finding ways to counter it or to predict its consequences. The primary purpose
of this study was to provide information about how the dynamics of K, Na, Ca, Mg and P are affected by acid deposition in
a typical forest in southern China.
Materials and Methods:
Experimental soils and saplings were collected directly from the monsoon evergreen broad-leaved forest in Dinghushan. All
saplings were transplanted individually into ceramic pots in August 2000 and placed in an open area near their origin site.
Pot soils were treated weekly from October, 2000 to July, 2002 with an acidic solution at pH 3.05, pH 3.52, pH 4.00 or pH
4.40, or with tap water as a control. The concentrations of SO42-, NO3-, K+, Na+, Ca2+, Mg2+ and available P and the pH were
measured in soil and leachate samples taken at different times. The sapling leaves were collected and their element concentrations
were measured at the end of the experiment.
Results:
Concentrations of soil exchangeable Ca and Mg decreased quickly over time, although only Ca showed changes with the acidic
solution treatment and soil exchangeable K was stable because of soil weathering. Leaching of K, Mg and Ca was dependent upon
the treatment acidity. Soil available P decreased slowly without any correlation with the acidity of the treatment. All the
NO3- added by the treatment was taken up by the plants, but the SO42- added accumulated in the soil.
Discussion:
Amongst the plant species, Schima superba was little affected by the treatment, the leaf P content was affected in Acmena
acuminatissima plants and Cryptocarya concinna was the most susceptible species to soil acidification, with a marked decrease
of the leaf K, Ca and Mg concentrations when the treatment acidity increased.
Conclusions:
Simulated acid deposition affected the dynamics of K, Ca and Mg in the monsoon evergreen broad-leaved forest. The dynamics
of Ca in the soil and of K, Mg and Ca in the soil leachates were affected by the acidic solution treatment. If such a soil
acidification occurs, Cryptocarya concinna will be amongst the first affected species, but Schima superba will be able to
sustain a good growth and mineral nutrition.
Recommendations and Perspectives:
Acid deposition will lead to imbalance the nutrient elements in the evergreen broad-leaved forest because of accelerated leaching
losses of soil exchangeable Ca and Mg. Measures should be developed to slow down soil acidification or nutrient decrease. 相似文献
478.
鞍山市大气尘和金属元素沉降通量及污染特征 总被引:5,自引:3,他引:2
通过采集鞍山市11个点位的降尘样品以及土壤样品,用ICP-MS分析了Cu、Mn、Zn、Pb等元素含量,并计算其沉降通量。结果表明,鞍山地区大气降尘的沉降通量为2.92~59.8g/(m2.month),其中鞍钢厂区沉降通量均值为31.6g/(m2.month),分别是周边地区和对照地区的4.72倍和10.5倍。重金属As、Cr、Pb和Cd的沉降通量分别为3.78、45.5、42.8、0.457g/(hm2.month)。降尘中各元素的富集系数为0.29~190,其中Cu、Fe、Zn、Mo、Cd、Pb和Se的富集系数大于10,说明这些元素主要来自于人为源。鞍钢厂区土壤中Cu、Pb、Mn、Zn、Mo、Cd、Ca、Fe和Se的含量较辽宁省土壤背景值高,说明其土壤环境已经受到了人类活动的影响。 相似文献
479.
K.M.S. Sundaram 《Journal of environmental science and health. Part. B》2013,48(5-6):601-629
Abstract Deposition and dissipation of aerially sprayed phosphamidon insecticide over a mixed forest consisting of different species of coniferous and deciduous trees were studied. The data showed that the chemical deposited more and dissipated slower from deciduous foliage than from conifer needles. Differences in deposits and persistence were also found within each of the two foliar types. Leaf shape and orientation, crown geometry and foliar morphology appear to have played a role. No correlation was found between initial deposit levels and cuticular wax content of different foliar species. A controlled laboratory study showed that surface area/mass ratio played a more important role on initial deposits than pubescence/serrations present on foliar surfaces. 相似文献
480.
Raquel Melgar Emilio Benitez Rogelio Nogales 《Journal of environmental science and health. Part. B》2013,48(5):488-495
The present work evaluates the possible bioconversion of wet olive cake by low-cost biostabilization (vermicomposting process). Wet olive cake fresh (WOC), precomposted (WOCP), or mixed with biosolids (WOCB), were vermicomposted for 6 months to obtain organic amendments for agricultural and remediation purposes. The results showed initial differences depending on previous treatment. WOCP was initially more stable, presented a low C:N ratio, and showed more dehydrogenase and urease activity. By contrast, there was no dehydrogenase activity initially in WOC and WOCB, due to the presence of some different types of polyphenols. Finally, the end product showed relatively higher amounts of total nitrogen and humic acid and met the standard of quality for composts and vermicomposts for use both in conventional and organic agriculture and soil-restoration programs. 相似文献