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 156 毫秒
711.
分别用混合酸湿法消解和微波消解两种方法处理鱼虾样品,用原子吸收法测定样品中铜、锌、铅、镉、铬的含量.结果表明微波消解相对标准偏差均在4.0%以下,加标回收率在95.6%~112%之间.湿法消解相对标准偏差在0.3%~5.6%之间,加标回收率在88.9%~115%之间.微波消解比湿法消解的精密度、准确度高,且微波消解操作安全简便,耗时短,适用于样品数量多的情况.混合酸湿法消解操作复杂,耗时长,由于使用了在高温下易爆的高氯酸,又容易发生"炭化"现象,安全性差,在样品数量少的情况下可用此法. 相似文献
712.
1987-1989年春秋季在西南重庆、贵阳、成都和广元等地区采集大气颗粒物和雨水样品,测定了其中S和SO4^2-。探讨了颗粒物中S在粗细粒中的分布及水溶性S的百分比,估算了大气中S在气相(SO2)、液相(H2SO4)及固相(SO4^2-)中的分配比例,得知颗粒物中S对降雨的贡献率为18~50%。 相似文献
713.
714.
介绍了可应用于垃圾渗滤液处理的三种人工湿地植物组合,并采用层次分析法从技术可行性、经济可行性、环境可行性三个方面对这三种组合进行了分析,得出了最优湿地植物组合为芦苇和风眼莲组合。 相似文献
715.
Predicting particle deposition on HVAC heat exchangers 总被引:2,自引:0,他引:2
Jeffrey A. Siegel William W Nazaroff 《Atmospheric environment (Oxford, England : 1994)》2003,37(39-40):5587
Particles in indoor environments may deposit on the surfaces of heat exchangers that are used in heating, ventilation and air conditioning (HVAC) systems. Such deposits can lead to performance degradation and indoor air quality problems. We present a model of fin-and-tube heat-exchanger fouling that deterministically simulates particle impaction, gravitational settling, and Brownian diffusion and uses a Monte Carlo simulation to account for impaction due to air turbulence. The model predicts that <2% of submicron particles will deposit on heat exchangers with air flows and fin spacings that are typical of HVAC systems. For supermicron particles, deposition increases with particle size. The dominant deposition mechanism for 1–10 μm particles is impaction on fin edges. Gravitational settling, impaction, and air turbulence contribute to deposition for particles larger than 10 μm. Gravitational settling is the dominant deposition mechanism for lower air velocities, and impaction on refrigerant tubes is dominant for higher velocities. We measured deposition fractions for 1–16 μm particles at three characteristic air velocities. On average, the measured results show more deposition than the model predicts for an air speed of 1.5 m s−1. The amount that the model underpredicts the measured data increases at higher velocities and especially for larger particles, although the model shows good qualitative agreement with the measured deposition fractions. Discontinuities in the heat-exchanger fins are hypothesized to be responsible for the increase in measured deposition. The model and experiments reported here are for isothermal conditions and do not address the potentially important effects of heat transfer and water phase change on deposition. 相似文献
716.
The EMEP/MSC-W routine model for long-range atmospheric transport of sulphur and nitrogen includes a correction for the unresolved sub-grid-scale deposition in emission grid-squares. A constant fraction of the emissions is assumed to be directly deposited inside the first grid-square. Experiments have been performed to estimate the effects of using factors which vary with emission height and meteorological conditions. Results indicate that the constant local deposition factor used for sulphur dioxide in the routine model, is an overestimate, in particular for high-level emission sources. The change in annual deposition caused by the new local deposition factor for sulphur dioxide, is most clearly seen as a decreased deposition in the grid-squares with the largest emissions such as due for the former German Democratic Republic. The amount of this decrease strongly depends on the source height distribution. With the presently available emission data, a decrease of maximum 36% can be expected in individual grid squares. In grid-squares dominated by transboundary deposition, the increase is typically lower than 10%. 相似文献
717.
718.
Carboxylic acids are ubiquitous and important components of the troposphere; they are currently measured in different environments. They are thought to have several sources comprising primary biogenic and anthropogenic emissions, hydrocarbons gas-phase oxidations, and some carbonyl compounds aqueous-phase oxidations. In the present review we make a synthesis of the concentrations of low molecular weight carboxylic acids in tropospheric aqueous and gaseous phases and in aerosol particles for different environments. We also successively examine the major sources of carboxylic acids and discuss their relative contribution to tropospheric concentrations for various environments as well as the principal sinks of these compounds. 相似文献
719.
Giaufausto Salvadori Sergio P. Ratti Giuseppe Belli 《Environmental science and pollution research international》1997,4(2):91-98
A few case studies will be presented involving both radioactive and chemical pollution at small, medium, and large space-time
scales. Reported are recent advances in the field of environmental pollution involving the use of fractals and multifractals.
The mathematical tools proposed here may offer new perspectives for investigating many of the problems of nonlinear variability
which commonly arise when dealing with pollutants, such as the presence of outliers and the sparseness of the sampling networks.
They may also lead to a simplification of the models adopted for studying natural phenomena, thanks to a scaling approach.
Finally, they may provide parameters whose values are directly related to the nonlinear dynamics involved in the pollutant
distribution in the environment which, in turn, may be relevant for computer simulation and epidemiological or risk assessment
purposes. 相似文献
720.
Herpin U Siewers U Markert B Rosolen V Breulmann G Bernoux M 《Environmental science and pollution research international》2004,11(1):57-66
This paper shows the geographic distribution in Germany of iron (Fe), nickel (Ni) and lead (Pb) analyzed in mosses in 1995/96 and compares it with the results of the 1990/91 pilot study within a European moss-monitoring programme. Other elements (As, Cd, Cr, Cu, Ti, V, Zn) are compared on basis of the overall element medians for Germany of the 1990/91 and 1995/96 survey. Samples of Pleurozium schreberi, Scleropodium purum, Hypnum cupressiforme and Hylocomium splendens were taken at a total of 1026 sites. In the 1995/96 monitoring campaign, 95% of the original sites of the 1990/91 study were resampled. The results from 1995/96 display local elevated values and many cases of areas affected by known sources of heavy-metal emissions. The industrialized and urban regions of Germany are shown up clearly by the 1995/96 moss-monitoring results: the Ruhr area, parts of Saarland and Baden-Württemberg, as well as areas in eastern Germany. Relatively low values for many elements were found in large areas of Lower Saxony and Bavaria. A comparison of the results of the 1990/91 and 1995/96 moss-monitoring programmes shows a fall in the concentration of the presented elements (except cadmium, copper and zinc) over the relevant period. Especially in the former GDR, chromium (Cr), iron (Fe), titanium (Ti) and vanadium (V) decreased significantly. This is, firstly, a reflection of the closure of and/or technological improvements to large power plants; secondly it is due to the fact that lignite has given way to other fuels. Vanadium (V) and nickel (Ni), typical constituents of crude oil, also show a decrease in the western part and thus document changes in the type of fuel consumed. The significant fall in lead concentration in 1995/96 as compared to 1990/91 in what used to be East and West Germany probably results from the increasing use of lead-free petrol. A comparison of the median values for 1990/91 and 1995/96 in mosses to the rate of emission of heavy metals in Germany for 1990 and 1995 shows similar trends in the case of elements such as arsenic (As), chromium (Cr), nickel (Ni), and lead (Pb). The comparison of the medians of the elements analyzed for 19 European countries indicates for most of the elements a general tendency to lower values in 1995, except for Lithuania, Netherlands, Portugal, Italy and United Kingdom. 相似文献