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891.
用Na_2CO_3催化焙烧法将CuS转化为Cu。最佳的转化条件;反应温度为750℃,CuS:Na_2CO_3(摩尔比)为1:2,在空气中反应90min。CuS的转化率可达到99%。  相似文献   
892.
针对农村玛瑙染色工业废水中存在高浓度Cr(Ⅵ)、SO42-和H+等污染严重、难处理的问题,基于玉米芯、花生壳和铁屑,分别构造了1#(玉米芯)、2#(花生壳)、3#(铁屑+玉米芯)、4#(铁屑+花生壳)动态柱实验模型,研究了生物质材料及其与铁屑协同处理玛瑙染色废水中Cr(Ⅵ)、SO42-、H+的效果和机理.结果表明,铁屑+玉米芯、铁屑+花生壳动态柱对Cr(Ⅵ)、SO42-的平均去除率分别为95.97%、96.42%和72.17%和59.55%,高于玉米芯、花生壳动态柱的89.67%、90.74%和39.00%、28.73%的平均去除率,且具有较强的抗污染负荷变化和一定的pH值提升的能力.对比分析可见,经过铁屑强化的生物质动态柱对Cr(Ⅵ)、SO42-、H+有更好、更稳定的去除效果.  相似文献   
893.
热解镀层石墨管在无标准分析法测定环境样品中镉的应用   总被引:1,自引:0,他引:1  
马怡载  朱雷 《环境化学》1994,13(4):332-339
本文选择了最佳实验条件和混俣基体改进剂(钯+酒石酸),使热解镀层石墨等有可能用于无标准分析法测定各种环境标准参考物质中的镉。引入有效原子化温度(Teff)概念后,在Teff大于1600K和使用钯和酒石酸为混合基体改进剂,用各种环境标准参考物溶液得到的实验特征量值,接近理论特征量值。  相似文献   
894.
小麦根系吸收土壤中的~(14)C-辛硫磷,经茎转运到植株地上各部分,累积在小麦叶片中的~(14)C-辛硫磷残留物再通过蒸腾、代谢和光解等途径不断转移和消解,或以~(14)CO_2,或以其它含~(14)C-化合物形式向体外逸出,经过整个生育期(90天)的转移和消解,麦收后土壤中仍有少量~(14)C-辛硫磷残留物,这些残留物或以含~(14)C土壤蒸发液形式、或由土壤微生物作用分解成~(14)CO_2逸出土壤。  相似文献   
895.
本文根据对南岳上封寺森林群落野外实地考察以及研究结果,选用了24个有代表性的物种多样性测定公式,并采用重要值、株数或鲜重、优势度或盖度作为测度指标对南岳上封寺森林群落植物物种多样性进行了研究。结果表明,南岳上封寺森林群落植物物种多样性水平较高,但又低于南岳广济寺。此外,不同测度指标对物种多样性指数的结果并无明显的规律性变化。  相似文献   
896.
Experiments were carried out on a diesel engine operating on Euro V diesel fuel, pure biodiesel and biodiesel blended with methanol. The blended fuels contain 5%, 10% and 15% by volume of methanol. Experiments were conducted under five engine loads at a steady speed of 1800 rev min−1 to assess the performance and the emissions of the engine associated with the application of the different fuels. The results indicate an increase of brake specific fuel consumption and brake thermal efficiency when the diesel engine was operated with biodiesel and the blended fuels, compared with the diesel fuel. The blended fuels could lead to higher CO and HC emissions than biodiesel, higher CO emission but lower HC emission than the diesel fuel. There are simultaneous reductions of NOx and PM to a level below those of the diesel fuel. Regarding the unregulated emissions, compared with the diesel fuel, the blended fuels generate higher formaldehyde, acetaldehyde and unburned methanol emissions, lower 1,3-butadiene and benzene emissions, while the toluene and xylene emissions not significantly different.  相似文献   
897.
Volatile organic compound (VOC) emissions from furnishings have created a major indoor air pollution problem in China. The aim of this study was to investigate the VOC emission of larch particleboard under different processing conditions. VOCs collection chamber, parts per billion VOC monitor, and gas chromatography–mass spectrometer were used to analyze the VOC components and quantities. The results were shown as follows: (1) concentration and emission rate of VOCs were significantly affected by hot-pressing temperature and time. With the increase of hot-pressing temperature and time, both the earlier emission concentration and the amount of total volatile organic compounds increased. (2) The composition of VOCs was also influenced by temperature and time, especially the variety of terpene, benzene, and derivative. The existence and quantities of esters were still the main components of VOCs emissions.  相似文献   
898.
Agricultural activity is one of the most important sources of aerosol particles. To understand the mass distribution and sources of aerosol particles and their inorganic water-soluble ions in a suburb farmland of Beijing, particle samples were collected using a microorifice uniform deposit impactor (MOUDI) in the summer of 2004 in a suburb vegetable field. The distribution of the particles and their inorganic water-soluble ions in the diameter range of 0.18–18 μm were measured. The dominant fine particle ions were SO4 2?, NO3 ?, and NH4 +. The association of day-to-day variation of the concentration of these ions with temperature, humidity, and solar radiation suggested that they are formed by the reaction of NH3 released from the vegetable field with the acid species produced from photochemical reactions. Fine particle K+ is likely from vegetation emission and biomass burning. Coarse particles like Ca2+, Mg2+, NO3 ?, and SO4 2? are suggested to come from the mechanical process by which the soil particle entered the atmosphere, and from the reaction of the acid species at the surface of the soil particle. The results show that fertilizer and soil are important factors determining the aerosol particle over agricultural fields, and vegetable fields in suburban Beijing contribute significantly to the aerosol particle.  相似文献   
899.
To supply the valuable operating parameters for the popular usage of the new denitrifying phosphors removal process, it is essential to study the dominant biochemical reactions and the characteristics of denitrifying phosphorus removing bacteria (DPB). Thus, parallel batch experiments using DPB sludge were carried out to assess the effect of substrates (sewage, HAc, and endogenous carbon source) on denitrifying dephosphorus removal efficiency in this study. The results showed that the initial specific phosphorus release rate increased with the high concentration of the short-chain volatile fatty acids ratio in the influent, and sufficient phosphorus was released by DPB. This improved the subsequent denitrification and phosphorus uptake efficiency. The specific endogenous denitrification mainly relies on the internal carbon source (PHB) stored by poly-P bacteria. Denitrifying phosphorus removing bacteria were very hungry when the internal PHB was consumed. Consequently, the specific endogenous denitrification rate was low and the phosphorus uptake did not happen. On the other hand, in the experiment, the denitrifying phosphorus removal performance under two temperature conditions (8–10°C and 25–26°C) was also investigated and analyzed. It was found that the lower temperature decreased the specific phosphorus release and uptake rate, but did not inhibit the denitrifying phosphorus removal completely. Therefore, the negative influence of the low temperature on the overall phosphorus removal was not significant.  相似文献   
900.
The aim of this paper is to determine and compare the environmental factors controlling vertical colonisation of periphyton on Sparganium erectum in a shallow eutrophic turbid lake, Manyas Lake, and an oligo-mesotrophic deep lake, Sapanca Lake, Turkey during the July 1997--November 1998. To investigate the effect of the environmental factors on periphyton colonization on S. erectum, the stem was cut above the rhizomes and subdivided into three equal sections. Multivariate statistical analyses have been applied to clarify relationships between environmental variables and periphyton colonization on S. erectum. Results indicated that physical disturbance and trophic level of the lakes influenced the colonization of the periphyton. Among the measured parameters, low light intensity, total suspended solids, temperature and water level fluctuation were observed as driving factors in Manyas Lake whereas nutrient deficiency was found as key factor in Sapanca Lake. The zonation of the periphyton, density, composition and dominant/subdominant taxa were significantly different in these lakes. However, Oedogonium sp., Mougeotia sp., Cylindrocapsa sp., Cladophora glomerata (Linn.), Aulacoseira italica (Ehr.) Simonsen, Melosira varians C. Agardh, Navicula tripunctata (O.F. Müller) Bory and Fragilaria ulna (Nitzsch) Lange-Bertalot were found as dominant species at all sections of S. erectum both in Manyas Lake and Sapanca Lake. It can be thought that these species have a broad range of tolerance to several physical, chemical and hydrologic disturbances. This is the first study to introduce how much the water quality and hydrologic drivers have affected vertical colonization of periphyton on S. erectum in two lakes with different mixing regimes.  相似文献   
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