全文获取类型
收费全文 | 32498篇 |
免费 | 416篇 |
国内免费 | 885篇 |
专业分类
安全科学 | 1027篇 |
废物处理 | 1584篇 |
环保管理 | 3829篇 |
综合类 | 5786篇 |
基础理论 | 8394篇 |
环境理论 | 19篇 |
污染及防治 | 8815篇 |
评价与监测 | 2270篇 |
社会与环境 | 1856篇 |
灾害及防治 | 219篇 |
出版年
2023年 | 161篇 |
2022年 | 393篇 |
2021年 | 409篇 |
2020年 | 297篇 |
2019年 | 352篇 |
2018年 | 550篇 |
2017年 | 574篇 |
2016年 | 864篇 |
2015年 | 679篇 |
2014年 | 1053篇 |
2013年 | 2661篇 |
2012年 | 1229篇 |
2011年 | 1611篇 |
2010年 | 1308篇 |
2009年 | 1316篇 |
2008年 | 1566篇 |
2007年 | 1601篇 |
2006年 | 1357篇 |
2005年 | 1166篇 |
2004年 | 1043篇 |
2003年 | 1132篇 |
2002年 | 1002篇 |
2001年 | 1274篇 |
2000年 | 892篇 |
1999年 | 552篇 |
1998年 | 377篇 |
1997年 | 382篇 |
1996年 | 381篇 |
1995年 | 442篇 |
1994年 | 463篇 |
1993年 | 368篇 |
1992年 | 386篇 |
1991年 | 362篇 |
1990年 | 390篇 |
1989年 | 343篇 |
1988年 | 301篇 |
1987年 | 282篇 |
1986年 | 227篇 |
1985年 | 251篇 |
1984年 | 265篇 |
1983年 | 260篇 |
1982年 | 243篇 |
1981年 | 224篇 |
1980年 | 177篇 |
1979年 | 194篇 |
1978年 | 176篇 |
1975年 | 140篇 |
1974年 | 117篇 |
1972年 | 131篇 |
1971年 | 133篇 |
排序方式: 共有10000条查询结果,搜索用时 18 毫秒
991.
Persistence and dissipation of flubendiamide and its risk assessment on gherkin (Cucumis anguria L.)
M. Paramasivam C. Selvi S. Chandrasekaran 《Environmental monitoring and assessment》2014,186(8):4881-4887
A supervised open field trial was conducted to evaluate the dissipation pattern and risk assessment of flubendiamide in gherkin fruits following foliar application of Fame 480 SC at 60 and 120 g a.i.?ha?1. Samples of gherkin fruits were drawn at different time intervals and quantified by HPLC-DAD. The maximum initial deposits of flubendiamide on gherkin were found to be 0.79 and 1.52 mg kg?1, respectively, at recommended and double the recommended doses. The dissipation pattern of flubendiamide followed a first-order kinetics with half-lives of 1.87 to 2.16 days at 60 and 120 g a.i.?ha?1, respectively. The limit of quantification of flubendiamide and desiodo flubendiamide was observed to be 0.01 mg kg?1 for gherkin fruit and soil substrates. Theoretical maximum residue contribution (TMRC) for flubendiamide was calculated and found to be well below the maximum permissible intake (MPI) on gherkin fruits. Thus, the application of flubendiamide at the recommended dose on gherkin fruits presents no human health risks and safe to consumers. 相似文献
992.
This research article demonstrates biodiesel synthesis through the methanolysis of the oily contents (4.02 ± 0.27% w/w on dried basis) of Dictyota dichotoma collected from the coast of Hawksbay, Pakistan. The metal oxides (CaO, MgO, ZnO, and TiO2) used as nanocatalysts were refluxed (5% K2SO4), calcinated (850 °C) and characterized by Atomic Force Microscopy (AFM) which produced 93.2% w/w FAME (biodiesel) at relatively mild condition (5% catalyst, 65 °C, 3 h, 18:1 molar ratio) using CaO. Whereas, MgO, ZnO, and TiO2 produced 92.4%, 72.5%, and 31.8% w/w FAME, respectively at elevated condition (225 °C). Thus, CaO was considered to be the best catalyst among the others. This tri-phase reaction require continuous fast mixing and the yield depends on the reaction parameters like catalyst amount, temperature, reaction time and molar ratio (methanol: oil). The reusability of these heterogeneous catalysts simplified the purification step, reduced the waste generation and make the final product technically and economically viable. 相似文献
993.
Bárbara Medeiros Fonseca Luciana de Mendonça-Galvão Claudia Padovesi-Fonseca Lucijane Monteiro de Abreu Adriana Cristina Marinho Fernandes 《Environmental monitoring and assessment》2014,186(1):19-33
The aquatic systems responsible for water supply in the Brazilian Federal District (FD) have been threatened by anthropogenic pressures, especially considering the expressive demographic increase in the region during the last decades. The purposes of this research were: (a) to assess the water quality in streams located in the FD by monitoring physical–chemical variables; (b) to define baselines for these variables among different ecological status categories. The 14 investigated streams were sampled between 2006 and 2009, in the dry (August–September, 2006, 2008, 2009) and rainy (March–April, 2008, 2009) seasons. All sampling sites were classified in four categories (“very impacted”, “impacted”, “in transition” and “natural”) using an adaptation of a rapid habitat assessment protocol. Differences in water quality among sites were generally well predicted in the four ecological status categories defined by the protocol, which showed a gradient in nutrient concentrations from reference sites classified as “natural” (medians: electrical conductivity?=?7.3 μS cm?1; nitrate?=?0.040 mg L?1; ammonium?=?0.039 mg L?1; soluble reactive phosphorus (SRP)?=?<0.001 mg L?1; total phosphorus (TP)?=?0.006 mg L?1; ) to those classified as “very impacted” (medians: electrical conductivity?=?87.7 μS cm?1; nitrate?=?0.247 mg L?1; ammonium?=?0.219 mg L?1; SRP?=?0.010 mg L?1; TP?=?0.035 mg L?1). Point sources inputs were the main factor for water quality deterioration. The nutrient baselines reported were relatively low when compared to data collected from reference areas in Brazil (e.g., São Paulo State) or temperate regions, especially for TP. 相似文献
994.
Hugo Olvera-Vargas Nihal Oturan C. T. Aravindakumar M. M. Sunil Paul Virender K. Sharma Mehmet A. Oturan 《Environmental science and pollution research international》2014,21(14):8379-8386
In this work, the electrochemical degradation of the dye azure B in aqueous solutions was studied by electrochemical advanced oxidation processes (EAOPs), electro-Fenton, and anodic oxidation processes, using Pt/carbon-felt and boron-doped diamond (BDD)/carbon-felt cells with H2O2 electrogeneration. The higher oxidation power of the electro-Fenton (EF) process using BDD anode was demonstrated. The oxidative degradation of azure B by the electrochemically generated hydroxyl radicals (?OH) follows a pseudo-first-order kinetics. The apparent rate constants of the oxidation of azure B by ?OH were measured according to pseudo-first-order kinetic model. The absolute rate constant of azure B hydroxylation reaction was determined by competition kinetics method and found to be 1.19?×?109 M?1 s?1. It was found that the electrochemical degradation of the dye leads to the formation of aromatic by-products which are then oxidized to aliphatic carboxylic acids before their almost mineralization to CO2 and inorganic ions (sulfate, nitrate, and ammonium). The evolution of the TOC removal and time course of short-chain carboxylic acids during treatment were also investigated. 相似文献
995.
M. El-Fadel J. Hashisho 《Journal of the Air & Waste Management Association (1995)》2014,64(9):1073-1084
The management of landfill leachate is challenging, with relatively limited work targeting high-strength leachate. In this study, the performance of the membrane bioreactor (MBR) and sequencing batch reactor (SBR) technologies are compared in treating high-strength landfill leachate. The MBR exhibited a superior performance with removal efficiencies exceeding 95% for BOD5, TN, and NH3 and an improvement on SBR efficiencies ranging between 21 and 34%. The coupled experimental results contribute in filling a gap toward improving the management of high-strength landfill leachate and providing comparative guidelines or selection criteria and limitations for MBR and SBR applications.
ImplicationsWhile the sequencing batch reactor (SBR) technology offers some flexibility in terms of cycle time and sequence, its performance is constrained when considering landfill leachate associated with significant variations in quality and quantity. Combining membrane separation and biodegradation processes or the membrane bioreactor (MBR) technology improved removal efficiencies significantly. In the context of leachate management using the MBR technology, more efforts have targeted low-strength leachate with limited attempts at moderate to high strength leachate. In this study, the SBR and MBR technologies were tested under different operating conditions to compare and evaluate their feasibility for the management of high-strength leachate from a full-scale operating landfill. Such a comparison has not been reported for high-strength leachate. 相似文献
996.
Luke M. Mosley Benjamin Zammit Ann-Marie Jolley Liz Barnett Rob Fitzpatrick 《Environmental monitoring and assessment》2014,186(1):1-18
Large-scale exposure of acid sulfate soils during a hydrological drought in the Lower Lakes of South Australia resulted in acidification of surface water in several locations. Our aim was to describe the techniques used to monitor, assess and manage these acidification events using a field and laboratory dataset (n?=?1,208) of acidic to circum-neutral pH water samples. The median pH of the acidified (pH?<?6.5) samples was 3.8. Significant (p?<?0.05) increases in soluble metals (Al, Co, Mn, Ni and Zn above guidelines for ecosystem protection), SO4 (from pyrite oxidation), Si (from aluminosilicate dissolution) and Ca (from carbonate dissolution and limestone addition), were observed under the acidic conditions. The log of the soluble metal concentrations, acidity and SO4/Cl ratio increased linearly with pH. The pH, alkalinity and acidity measurements were used to inform aerial limestone dosing events to neutralise acidic water. Field measurements correlated strongly with laboratory measurements for pH, alkalinity and conductivity (r 2?≥?0.97) but only moderately with acidity (r 2?=?0.54), which could be due to difficulties in determining the indicator-based field titration endpoint. Laboratory measured acidity correlated well with calculated acidity (r 2?=?0.87, acidity present as AlIII?>>?H+?≈?MnII?>?FeII/III) but was about 20 % higher on average. Geochemical speciation calculations and XRD measurements indicated that solid phase minerals (schwertmannite and jarosite for Fe and jurbanite for Al) were likely controlling dissolved metal concentrations and influencing measured acidity between pH 2 and 5. 相似文献
997.
998.
A. R. T. S. Araujo M. C. Sarraguça M. P. Ribeiro P. Coutinho 《Environmental geochemistry and health》2017,39(3):483-496
Mineral natural waters and spas have been used for therapeutic purposes for centuries, with Portugal being a very rich country in thermal waters and spas that are mainly distributed by northern and central regions where Beira Interior region is located. The use of thermal waters for therapeutic purposes has always been aroused a continuous interest, being dependent on physicochemical fingerprinting of this type of waters the indication for a treatment in a specific pathological condition. In the present work, besides a literature review about the physicochemical composition of the thermal waters of the Beira Interior region and its therapeutic indications, it was carried out an exhaustive multivariate analysis—principal component analysis and cluster analysis—to assess the correlation between different physicochemical parameters and the therapeutic indications claims described for these spas and thermal waters. These statistical methods used for data analysis enables classification of thermal waters compositions into different groups, regarding to the different variable selected, making possible an interpretation of variables affecting water compositions. Actually, Monfortinho and Longroiva are clearly quite different of the others, and Cró and Fonte Santa de Almeida appear together in all analysis, suggesting a strong resemblance between these waters. Thereafter, the results obtained allow us to demonstrate the role of major components of the studied thermal waters on a particular therapeutic purpose/indication and hence based on compositional and physicochemical properties partially explain their therapeutic qualities and beneficial effects on human health. This classification agreed with the results obtained for the therapeutic indications approved by the Portuguese National Health Authority and proved to be a valuable tool for the regional typology of mineral medicinal waters, constituting an important guide of the therapeutic armamentarium for well and specific-oriented pathological disturbs. 相似文献
999.
Feurdean Angelica Munteanu Catalina Kuemmerle Tobias Nielsen Anne B. Hutchinson Simon M. Ruprecht Eszter Parr Catherine L. Perşoiu Aurel Hickler Thomas 《Regional Environmental Change》2017,17(8):2193-2207
Regional Environmental Change - Traditional farming landscapes in the temperate zone that have persisted for millennia can be exceptionally species-rich and are therefore key conservation targets.... 相似文献
1000.
Vinicius T. Kütter Monica Wallner-Kersanach Silvia M. Sella Ana Luiza S. Albuquerque Bastiaan A. Knoppers Emmanoel V. Silva-Filho 《Environmental monitoring and assessment》2014,186(1):559-573
This long-term study, performed during the years 2003–2005 and 2008–2009, investigated the carbon (C), nitrogen (N), and phosphorus (P) contents of the phyto- and zooplankton communities and the nutrient regime of Cabo Frio Bay, SE Brazil. The information intends to serve as baseline of the plankton C, N, and P stoichiometry for the calibration of biogeochemical and ecological models in support to future findings related to the local and regional phenomena of climatic change. Cabo Frio Bay is a small semienclosed system set adjacent to a region subject to sporadic coastal upwelling. Zooplankton exhibited average annual C, N, and P contents of 11.6?±?6.9 %, 2.8?±?1.8 %, and 0.18?±?0.08 %, and phytoplankton (>20 μm) 6.8?±?6.0 %, 1.6?±?1.5 %, and 0.09?±?0.08 %, respectively. The C/N/P ratios correspond to the lowest already found to date for a marine environment. The low C contents must have been brought about by a predominance of gelatinous zooplankton, like Doliolids/ Salps and also Pteropods. Average annual nutrient concentrations in the water were 0.21?±?0.1 μM for phosphate, 0.08?±?0.1 μM for nitrite, 0.74?±?1.6 μM for nitrate, and 1.27?±?1.1 μM for ammonium. N/P ratios were around 8:1 during the first study period and 12:1 during the second. The plankton C/N/P and N/P nutrient ratios and elemental concentrations suggest that the system was oligotrophic and nitrogen limited. The sporadic intrusions of upwelling waters during the first study period had no marked effect upon the systems metabolism, likely due to dilution effects and the short residence times of water of the bay. 相似文献