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   6197篇
  免费   56篇
  国内免费   26篇
安全科学   88篇
废物处理   391篇
环保管理   422篇
综合类   889篇
基础理论   1322篇
环境理论   9篇
污染及防治   2190篇
评价与监测   561篇
社会与环境   392篇
灾害及防治   15篇
  2023年   71篇
  2022年   178篇
  2021年   221篇
  2020年   84篇
  2019年   82篇
  2018年   218篇
  2017年   198篇
  2016年   318篇
  2015年   175篇
  2014年   363篇
  2013年   596篇
  2012年   396篇
  2011年   388篇
  2010年   302篇
  2009年   222篇
  2008年   363篇
  2007年   382篇
  2006年   304篇
  2005年   224篇
  2004年   179篇
  2003年   159篇
  2002年   146篇
  2001年   85篇
  2000年   67篇
  1999年   52篇
  1998年   25篇
  1997年   19篇
  1996年   17篇
  1995年   34篇
  1994年   24篇
  1993年   15篇
  1992年   11篇
  1991年   10篇
  1990年   14篇
  1989年   9篇
  1985年   7篇
  1967年   9篇
  1966年   13篇
  1965年   16篇
  1964年   31篇
  1963年   12篇
  1962年   17篇
  1961年   11篇
  1960年   9篇
  1959年   27篇
  1958年   37篇
  1957年   20篇
  1956年   14篇
  1955年   19篇
  1954年   7篇
排序方式: 共有6279条查询结果,搜索用时 31 毫秒
191.
Elimination of alkylphenol ethoxylates (APEO) and their degradation products (alkylphenols and alkylphenoxy carboxylates), as well as linear alkylbenzene sulfonates (LAS) and coconut diethanol amides (CDEA), was studied in a pilot plant membrane bioreactor (MBR) working in parallel to a full-scale wastewater treatment plant (WWTP) using conventional activated sludge (CAS). In the CAS system 87% of parent long ethoxy chain NPEOs were eliminated, but their decomposition yielded persistent acidic and neutral metabolites which were poorly removed. The elimination of short ethoxy chain NPEOs (NP(1)EO and NP(2)EO) averaged 50%, whereas nonylphenoxy carboxylates (NPECs) showed an increase in concentrations with respect to the ones measured in influent samples. Nonylphenol (NP) was the only nonylphenolic compound efficiently removed (96%) in the CAS treatment. On the other hand, MBR showed good performance in removing nonylphenolic compounds with an overall elimination of 94% for the total pool of NPEO derived compounds (in comparison of 54%-overall elimination in the CAS). The elimination of individual compounds in the MBR was as follows: 97% for parent, long ethoxy chain NPEOs, 90% for short ethoxy chain NPEOs, 73% for NPECs, and 96% for NP. Consequently, the residual concentrations were in the low mug/l level or below it. LAS and CDEA showed similar elimination in the both wastewater treatment systems that were investigated, and no significant differences were observed between the two treatment processes. Nevertheless, for all studied compounds the MBR effluent concentrations were consistently lower and independent of the influent concentrations. Additionally, MBR effluent quality in terms of chemical oxygen demand (COD), NH(4)(+) concentration and total suspended solids (TSS) was always superior to the ones of the CAS and also independent of the influent quality, which demonstrates high potential of MBRs in the treatment of municipal wastewaters.  相似文献   
192.
In this work, the treatment of an actual industrial waste with three advanced oxidation processes (AOP) has been studied: conductive-diamond electrooxidation (CDEO), ozonation and Fenton oxidation. The wastewater comes from olive-oil mills (OMW) and contains a COD of nearly 3000 mg dm(-3). CDEO allowed achieving the complete mineralization of the waste with high current efficiencies. Likewise, both ozonation and Fenton oxidation were able to treat the wastes, but they obtained very different results in terms of efficiency and mineralization. The accumulation of oxidation-refractory compounds as final products excludes the use of ozonation and Fenton oxidation as a sole treatment technology. This confirms that besides the hydroxyl-radical mediated oxidation, CDEO combines other important oxidation processes such as the direct electro-oxidation on the diamond surface and the oxidation mediated by other electrochemically formed compounds generated on this electrode.  相似文献   
193.
Chelant-enhanced phytoextraction of heavy metals is an emerging technological approach for a non-destructive remediation of contaminated soils. The main objectives of this study were (i) to assess the extraction efficiency of two different synthetic chelating agents (ethylenediaminetetraacetic acid (EDTA) and ethylenediaminedisuccinic acid (EDDS)) for desorbing Pb from two contaminated agricultural soils originating from a mining and smelting district and (ii) to assess the phytoextraction efficiency of maize (Zea mays) and poplar (Populus sp.) after EDTA application. EDTA was more efficient than EDDS in desorbing and complexing Pb from both soils, removing as much as 60% of Pb. Maize exhibited better results than poplar when extracting Pb from the more acidic (pH approximately 4) and more contaminated (up to 1360 mg Pb kg(-1)) agricultural soil originating from the smelting area. On the other hand, poplars proved to be more efficient when grown on the near-neutral (pH approximately 6) and less contaminated (up to 200 mg Pb kg(-1)) agricultural soil originating from the mining area. Furthermore, the addition of EDTA led to a significant increase of Pb content especially in poplar leaves, proving a strong translocation rate within the poplar plants.  相似文献   
194.
A method for simultaneous quantitative determination of alkyl benzyl, dialkyl and trialkyl quaternary ammonium compounds (QACs) has been developed, validated and subsequently applied to real water samples in Austria. The method employs liquid-liquid extraction (LLE) followed by liquid chromatography/tandem mass spectrometry (LC-MS/MS), using electrospray ionization (ESI) in positive mode. The overall method quantification limits range from 4 to 19ng/L for the enrichment of 500mL water samples and analyte recoveries are between 80 and 99%. The method was applied to 62 of the respective water samples without filtration to avoid the loss of the analytes due to the high adsorption capacity of these compounds. Maxima in the mg/L range, especially in the wastewater of hospitals and laundries, could be detected for the selected target compounds.  相似文献   
195.
The characterisation by ICP-MS of an isolated Pu-U hot particle originating from the nuclear weapons accident in Palomares (Spain) shows, for the first time, that its uranium content is highly enriched in (235)U. The enrichment has been confirmed by independent analyses of two surface soil samples collected in a heavily contaminated area close to the impact point of one of the bombs. This finding clarifies better the composition of the weapons involved in the accident and is of importance when the inventory of U and Pu in the contaminated area are to be calculated.  相似文献   
196.
National POPs inventories carried out currently in many countries as a part of the implementation of Stockholm Convention revealed the need for detailed information about a distribution of pollutants in various regions. Screening for the residues of selected organochlorinated pesticides (chlordane, heptachlor, dieldrin, aldrin, endrin, isodrin, endosulfan I, endosulfan II, methoxychlor, mirex) in soil and biotic samples from the Czech Republic was performed. Although these pesticides have never been used in large quantities in this region, results indicate that their residues still persist in the top layer soils more than 20 years after they have been banned. The fact that their soil concentrations in the mountains are generally higher than those in agricultural areas, and detection of the traces of pesticides that have never been used in this region suggest on their occurrence in soils due to the atmospheric redistribution rather than as a result of direct application.  相似文献   
197.
A pilot-scale pyrolysis process was carried out for the treatment of a mixture of two types of waste, sewage sludge and cattle manure, comparing the results with others obtained under laboratory conditions (semi-pilot scale). The aim of this study was to obtain the energetic valorization of the products. Owing to the specific characteristics of the plant, two products were obtained from the process: gas and carbonized solid. As no liquid fraction was obtained, the gas fraction is a greater percentage made up of both condensable and non-condensable compounds, which were obtained separately at the laboratory scale. The pilot plant was designed so that the gases produced by thermolysis were burnt continuously in a combustion chamber, while the carbonized fraction was fed in batches for co-combustion. To determine composition and combustion ability, the gas and solid products from the pilot process were characterized by chromatographic analysis of the gaseous fraction and chemical analysis and programmed-temperature combustion of the carbonized solid. The composition of the combustion gases, rich in light hydrocarbons, and the carbon present in the carbonized fraction enable the energetic valorization of these products. The combustion gases were subjected to a cleaning process and their composition analysed twice: before and after the gas cleaning treatment. The study led to a positive assessment of the possible use of the process products as fuel, provided that the combustion gases are treated. As most of the sulphur and chlorine from the original waste are mainly concentrated in the solid fraction, the use of char as a fuel will depend on the effectiveness of clean-up techniques for combustion gases. During gas cleansing, neutralizing with sodium bicarbonate proved effective, especially for the acidic compounds HCl, HF and SO(2).  相似文献   
198.
The chemical and biological properties of compost made from yard trimmings (YT) composted alone or mixed with slaughterhouse wastes (SHW) were evaluated in seven phases. Mixtures were weighed in a 2:1 proportion (YT:SHW) and placed in composting bins (0.91 m2). Temperature was recorded to determine the time (d) needed to reach the first (1HC) and second heat cycles (2HC). Composting characteristics were measured at 0 d, at the peak of the 1HC and 2HC, and at maturation (0, 20, 50 and 70 d). During 1HC, bacterial isolates were cultivated in both treatments and identified using the Biolog System. Chemical composition was statistically analyzed using a 2 (layers of SHW)x7 (composting phases) factorial arrangement of treatments with the ANOVA procedure of SAS. The pH was neutral for YT and ranged from 7.41 to 6.82 for SHW throughout the process. There was a decrease in organic matter (OM) and carbon (C), and a relative increase in nitrogen (N) in both treatments. At 70 d of maturation, C:N values were similar between treatments, but lower (P>0.05) than the initial values. Final N concentration was higher (P>0.05) for the treatment with SHW. Only the SHW treatment exhibited thermophilic temperatures. At the 1HC in both treatments, different populations of bacteria responsible for the breakdown of OM were identified showing an active heterogeneous population. The presence of pathogenic microorganisms was not detected in treatments containing SHW.  相似文献   
199.
Otero M  Gómez X  García AI  Morán A 《Chemosphere》2007,69(11):1740-1750
Combustion of urban sewage sludge together with coal in existing infrastructures may be a sustainable management option energetically interesting for these materials, usually considered wastes. Thermogravimetric analysis was used to study the combustion of a semianthracite coal and the modifications undergone when adding a small percentage (2%, 5%, 10%) of sewage sludge. Both Differential Scanning Calorimetric analysis and Differential Thermogravimetry burning profiles showed differences between coal and sewage sludge combustion. However, the effects of adding a percentage of sewage sludge equal or smaller than 10% was hardly noticeable in terms of heat release and weight loss during the coal combustion. This was further proved by non-isothermal kinetic analysis, which was used to evaluate the Arrhenius activation energy corresponding to the co-combustion of the blends. This work shows that thermogravimetric analysis may be used as an easy rapid tool to asses the co-combustion of sewage sludge together with coal.  相似文献   
200.
This study examines the feasibility of coupling a Catalytic Wet Air Oxidation (CWAO), with activated carbon (AC) as catalyst, and an aerobic biological treatment to treat a high-strength o-cresol wastewater. Two goals are pursued: (a) To determine the effect of the main AC/CWAO intermediates on the activated sludge of a municipal WasteWater Treatment Plant (WWTP) and (b) To demonstrate the feasibility of coupling the AC/CWAO effluent as a part of the influent of a municipal WWTP. In a previous study, a high-strength o-cresol wastewater was treated by AC/CWAO aiming to establish the distribution of intermediates and the biodegradability enhancement. In this work, the biodegradability, toxicity and inhibition of the most relevant intermediates detected in the AC/CWAO effluent were determined by respirometry. Also, the results of a pilot scale municipal WWTP study for an integrated AC/CWAO-aerobic biological treatment of this effluent are presented. The biodegradation parameters (i.e. maximum oxygen uptake rate and oxygen consumption) of main AC/CWAO intermediates allowed the classification of the intermediates into readily biodegradable, inert or toxic/inhibitory compounds. This detailed study, allowed to understand the biodegradability enhancement exhibited by an AC/CWAO effluent and to achieve a successful strategy for coupling the AC/CWAO step with an aerobic biological treatment for a high-strength o-cresol wastewater. Using 30%, as COD, of AC/CWAO effluent in the inlet to the pilot scale WWTP, the integrated AC/CWAO-biological treatment achieved a 98% of total COD removal and, particularly, a 91% of AC/CWAO effluent COD removal without any undesirable effect on the biomass.  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