全文获取类型
收费全文 | 2280篇 |
免费 | 95篇 |
国内免费 | 727篇 |
专业分类
安全科学 | 127篇 |
废物处理 | 153篇 |
环保管理 | 153篇 |
综合类 | 1244篇 |
基础理论 | 394篇 |
污染及防治 | 761篇 |
评价与监测 | 98篇 |
社会与环境 | 82篇 |
灾害及防治 | 90篇 |
出版年
2024年 | 1篇 |
2023年 | 21篇 |
2022年 | 99篇 |
2021年 | 73篇 |
2020年 | 59篇 |
2019年 | 60篇 |
2018年 | 78篇 |
2017年 | 91篇 |
2016年 | 85篇 |
2015年 | 107篇 |
2014年 | 158篇 |
2013年 | 184篇 |
2012年 | 164篇 |
2011年 | 180篇 |
2010年 | 145篇 |
2009年 | 114篇 |
2008年 | 123篇 |
2007年 | 114篇 |
2006年 | 126篇 |
2005年 | 101篇 |
2004年 | 80篇 |
2003年 | 92篇 |
2002年 | 78篇 |
2001年 | 92篇 |
2000年 | 96篇 |
1999年 | 91篇 |
1998年 | 90篇 |
1997年 | 62篇 |
1996年 | 67篇 |
1995年 | 65篇 |
1994年 | 42篇 |
1993年 | 40篇 |
1992年 | 27篇 |
1991年 | 14篇 |
1990年 | 16篇 |
1989年 | 9篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1973年 | 1篇 |
排序方式: 共有3102条查询结果,搜索用时 140 毫秒
651.
谷孝鸿 《生态与农村环境学报》1994,(4)
鲁西北地区是黄淮海平原中低产田渍涝洼地的主要分布区之一。在鲁西北的禹城市,利用挖鱼塘、建台田的工程措施,综合改造利用这类洼地。工程实施后,通过水盐调控,改善了洼地的环境状况。监测结果表明:洼地台田土壤含盐量降低,土壤逐渐熟化。土壤有机质大量整治前后分别为0.582%(1986年)、0.989%(1989年).土壤中的全氮、全磷也由整冶前的0.02%、0.14%上升到整治后的0.061%和0.158%。土壤盐分含量逐年降低,由0.50~0.92%下降到0.06~O29%。挖鱼塘建台田的生态工程措施,使浅层地下水地表化,解决了洼地积水蒸发等形成的盐渍化问题。综合环境效应显示,洼地原有的自然状况向良性转化,达到了初步治理的目的。 相似文献
652.
沈兵 《生态与农村环境学报》1997,(1)
苍山洱海是国家级自然保护区,同时又是国家级风景名胜区,由于旅游业的开展而引发的环境、生态问题日趋突出。针对客观实际,在保护和开发并举的原则下,对该区域的旅游区、旅游模式等进行了规划,提出了旅游区域的环境保护指标、旅游容量,同时制定了相应的管理措施 相似文献
653.
水样品中重碳酸根离子排斥色谱法研究 总被引:3,自引:0,他引:3
本文研究了用离子排斥色谱法分析了水样品中重碳酸根的最佳色谱条件,分离方式和流动相的选择,样品溶液pH值与峰高的关系,实验结果显示,该方法具有简便,用样量少,灵敏度高于和干扰少等优点,测量下限为0.12μg.ml^-1HCO^-3在1-10μg.m^-1和10-100μg.ml^-1浓度范围内,HCO3浓度与峰高的线性相关系数在0.995以上,该方法用于自来水和油田水样品的分析获得较好的结果。 相似文献
654.
655.
Spectroscopic characterization of the structural and functional properties of natural organic matter fractions 总被引:31,自引:0,他引:31
Natural organic matter (NOM) is known to be complex in nature with varying structural and functional characteristics. In this study, an aquatic NOM was fractionated into the polyphenolic-rich (NOM-PP) and the carbohydrate-rich (NOM-CH) fractions in an attempt to better characterize their chemical and structural properties along with a reference soil humic acid (SHA). Various spectroscopic techniques were employed for the study, including ultraviolet-visible (UV/Vis). 13C-nuclear magnetic resonance, Fourier-transform infrared, fluorescence, and electron paramagnetic resonance spectroscopies. Results indicate that the relative abundance of aromatic C=C and methoxyl (-OCH3) functional groups are in the order of SHA > NOM-PP > NOM-CH. However, the aquatic NOM-PP and NOM-CH fractions are characterized by high contents of carboxylic and alcoholic functional groups relative to the SHA. In particular, the NOM-PP fraction appears to contain more phenolic and ketonic functional groups than the NOM-CH and SHA fractions, and it gives a strong fluorescence and high paramagnetic spin count. On the other hand, the NOM-CH fraction possesses a relatively low amount of carbon but a high amount of oxygen or oxygen-containing structural features, such as carbohydrate-OH and carboxylic groups, and shows the least fluorescence intensity and paramagnetic spin counts. Results of these spectroscopic studies confirm the heterogeneous nature of NOM, and point out the importance of isolation and improved characterization of various NOM subcomponents in order to better understand the behavior and roles of NOM in the natural environment. 相似文献
656.
The acute toxicity, bioaccumulation, and elimination of avermectin B1a (AVM B1a) in earthworm (Eisenia fetida) were investigated in different exposure systems. The LC50 of AVM B1a on earthworms were 24.1 mg/kg and 17.1 mg/kg, respectively, for 7 and 14 days in artificial soil. The LC50 tested by the filter paper for 2 days was 4.63 microg/cm2. The earthworms were cultivated in artificial soil containing 0.6 mg/kg and 3.0 mg/kg AVM B1a, respectively for bioaccumulation experiments. The AVM B1a residues in earthworms were determined with HPLC-fluorescence method. The results showed that AVM B1a was taken up from the concentrated artificial soil by the earthworms and the steady-state levels were reached after 9-18 days of exposure. On the 18th day, the final concentrations of AVM B1a in the earthworms treated with two different dosages were 107 ng/g and 165 ng/g, respectively; there were not significantly accumulation. About 80.0% and 94.8% of the accumulated AVM B1a were eliminated respectively in two groups within 1 day after they were exposed to AVM B1a-free soil, but a trace amount of AVM B1a was found for a relative long time in earthworms. 相似文献
657.
To gain information on organic pollutants in water-sediment systems, a compartment model was applied to study the sorption course of phenanthrene and pentachlorophenol (PCP) in sediments. The model described the time-dependent interaction of phenanthrene and PCP with operationally defined reversible and irreversible (or slowly reversible) sediment fractions. The interactions between these fractions were described using first order differential equations. By fitting the models to the experimental data, apparent rate constants were obtained using numerical optimization software. The model optimizations showed that the amount of reversible phase increased rapidly in the first 10 d with the sorption time, then decreased after 10 d, while the amount of irreversible phase increased in the total sorption course. That suggested the mass transport between reversible phase and irreversible phase. The extraction efficiency with hot methanol ranged from 36% to 103% for phenanthrene and from 65% to 101% for PCP, with the trend of decreasing with sorption time. 相似文献
658.
Degradation of dyes in aqueous solutions by the Fenton process 总被引:3,自引:0,他引:3
Degradation of 20 different dyes in aqueous solutions by the Fenton process was performed. These dyes include 6 types: acidic, reactive, direct, cationic, disperse and vat dyes. The former four types of dyes were decolorized and their TOC values were decreased greatly, while the color and TOC removals of the latter two types were lower. The catalytic activities of four metal ions on the degradation efficiencies of Vat Blue BO, which was chosen as a model dye because of its lowest color and TOC removals, were compared in the dark and under the ultraviolet light irradiation. The catalytic ability of different metals was Fe2+>Cu2+>Mn2+>Ag+ in the dark, and the same sequence was obtained under irradiation condition with greater degradation efficiency. Furthermore, the efficiencies of three oxidation processes, including H2O2/UV, Fe2+/H2O2 and Fe2+/H2O2/UV were compared. The results showed that the oxidation by Fe2+/H2O2/UV was the strongest, and even greater than the arithmetic sum of the other two processes, which suggests the synergistic effect of ultraviolet and ferrous ions on the degradation reaction. 相似文献
659.
An enrichment consortium and an isolate (isolate TKW) of sulfate-reducing bacteria (SRB) have been obtained from metal-contaminated marine sediments of Tokwawan, Hong Kong SAR. These bacteria are capable of reducing highly toxic and soluble hexavalent chromium (Cr6+) enzymatically into less toxic and insoluble trivalent chromium (Cr3+) under anaerobic conditions. The enrichment consortium almost completely (98.5%) reduced 0.6 mM Cr6+ in 168 h and the rate of reduction was 0.5 g (Cr6+) g(protein)(-1)h(-1). In comparison, with Cr6+ as the sole electron acceptor (as a surrogate for SO4(2-)), isolate TKW reduced 94.5% of the initially added Cr6+ (0.36 mM) in 288 h, with the rate of 0.26 g (Cr6+) g(protein)(-1)h(-1). Adsorption by these bacteria was not the major mechanism contributing to the transformation or removal of Cr6+. The biomass and Cr3+ in the cultures increased simultaneously with the reduction of Cr6+. These indigenous SRB might have potential application in bioremediation of metal contaminated sediments. 相似文献
660.
高氨氮对厌氧生物法处理城市垃圾渗沥液的影响 总被引:1,自引:0,他引:1
研究了高浓度氨氮对厌氧膜生物法处理城市垃圾渗沥液的影响。结果表明,COD去除率、沼气产量、沼气产率、辅酶F420和最大比产甲烷活性均随氨氮浓度的增加而减小;当氨氮浓度〈3600mg/L时,不会对厌氧膜生物反应器的运行产生明显的影响;氨氮对厌氧污泥产甲烷活性的50%抑制浓度为4350mg/L;高浓度氨氮会造成系统VFA浓度增加;当氨氮浓度由4800mg/L降低到2000mg/L后,受重度抑制的厌氧微生物的活性可以在20d里恢复到未受抑制时的活性水平。 相似文献