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71.
Composite Biofilms grown in Acidic Mining Lakes and assessed by Electron Microscopy and Molecular Techniques 总被引:1,自引:0,他引:1
Heinrich Lünsdorf Dirk F. Wenderoth Wolf-Rainer Abraham 《Water, Air, & Soil Pollution: Focus》2002,2(3):69-79
Microbial consortia of composite biofilms, grown in surface water of acidicmining lakes near Lauchhammer, Germany, were investigated. The red-brown colored lake water was acidic (pH 2.5), had high concentrations of Fe(III), Al(III), and sulphate and low concentrations of dissolved organic matter. As a result the abundance of bacteria in the lake is with 104 cells mL-1 rather low. One input of organic material into the lake are autumnal leaves from trees, growing in the lakeside area. From aliquots of unfixed birch leave biofilms the 16S rRNA genes were amplified by PCR and community fingerprints were determined by single-strand conformation polymorphism (SSCP) analysis. Specific bands within the fingerprints were extracted from SSCP gels and sequenced for the taxonomical affiliation.These results were compared with those from the second type of biofilms which were grown on sterile substrata, floating submersed in surface waters of the lakes. By excising the bands from the gel and sequencing the individual bands bacterial taxa, common to both types of biofilms, were found but also some, which were only present in one type of biofilm. Ultrathin sectioned biofilms often showed bacteria associated with electron dense particles as main inorganic constituents. Elemental microanalysis by energy dispersive X-ray analysis (EDX) revealed them to contain iron, sulfur and oxygen as main elemental fractions and electron diffraction ring pattern analysis classified them to be schwertmannite. These bacteria and their interactions with each other as well as with the inorganic minerals formed in this lake generally is of great interest, in order to use these results for bioremediation applications. 相似文献
72.
有机质提升对酸性红壤氮循环功能基因及功能微生物的影响 总被引:4,自引:0,他引:4
外源有机物质输入是提升酸性红壤有机质含量的主要方式,氮素是土壤肥力的重要限制因子.有机质提升后土壤生态系统的变化会影响土壤氮循环过程及功能微生物,但目前还未见报道.本研究选择长期施有机肥的酸性旱地红壤及不施肥对照土壤作为研究材料,基于宏基因组测序及氮循环功能基因数据库比对,研究32 a的连续有机物质输入导致的土壤有机质含量上升对酸性红壤氮循环功能基因及相关功能微生物的影响.结果表明,酸性红壤有机质提升显著增加了土壤总有机碳和总氮含量,缓解了土壤酸化.有机质提升增加了土壤净硝化活性和氨氧化潜势.有机质提升显著增长了编码古菌氨单加氧酶amoA基因和反硝化过程还原酶的功能基因nar、nap、nir、nor和nos的丰度,降低了编码羟胺氧化酶hao基因及执行硝酸盐异化还原成铵过程的功能基因nrf的丰度,提升了有机氮代谢功能基因glnA、gdh、glsA、ansB和nao丰度,改变了硝酸盐同化过程功能基因丰度以及硝化过程功能微生物群落组成.有机质提升后土壤酸化的缓解和总有机碳含量的提升是影响氮循环各过程功能基因丰度及功能微生物组成的最主要因子.本研究全面研究了无机氮和有机氮循环功能基因,关联了氨氧化过程的功能基因、功能微生物类群和功能活性,可为把握酸性红壤氮循环特征提供数据依据,也可为酸性土壤改良提供思路. 相似文献
73.
采用28 d室内连续培养实验,以纳米氢氧化镁和普通氢氧化镁(100、200和300 mg·kg-1)为镉污染土壤钝化剂,研究了纳米氢氧化镁和普通氢氧化镁对不同类型镉污染土壤(1、5、10和15 mg·kg-1)中镉形态的影响.结果表明,在中性土壤上,1、5、10和15 mg·kg-1镉处理中土壤交换态Cd (EX-Cd)形态分布比例FDC为66.7%~81.8%,为土壤镉主要形态.土壤镉含量大小顺序为EX-Cd > 碳酸盐结合态Cd(CAB-Cd) > 残渣态Cd (RES-Cd) > 铁锰氧化态Cd (FeMn-Cd) > 有机结合态Cd (OM-Cd).培养第14d时,土壤EX-Cd FDC达到最低值.培养0~28 d期间,在1、5、10和15 mg·kg-1镉处理下,纳米氢氧化镁和普通氢氧化镁处理的土壤EX-Cd FDC较对照(CK)分别降低了11.4%~67.7%、7.8%~37.2%、7.7%~36.4%、5.0%~28.8%(纳米氢氧化镁)和0.5%~49.5%、0.6%~15.0%、1.0%~18.1%、0.7%~14.6%(普通氢氧化镁).碱性土EX-Cd含量均在培养的第7 d时达到最低;酸性土在1、5和10 mg·kg-1镉处理中土壤EX-Cd含量在第21d时达到最低值.纳米氢氧化镁和普通氢氧化镁均降低了中、酸、碱性土壤EX-Cd含量,且随氢氧化镁施加量的增加,土壤EX-Cd含量呈降低趋势.相同用量下,钝化土壤活性镉的效果以纳米氢氧化镁优于普通氢氧化镁. 相似文献
74.
75.
目的研究交流杂散电流干扰下管线钢的腐蚀机理。方法采用电化学阻抗谱(EIS)、动电位极化扫描(Tafel)等电化学测试技术和表面分析技术研究不同交流电流密度干扰下(0~80 A/m~2)X80管线钢在酸性土壤环境中的腐蚀行为。结果酸性土壤环境中,即使是10 A/m~2的交流电流密度,也会引起X80的交流腐蚀,且钢的腐蚀速率随着交流电流密度的增大而增大。未施加交流电干扰时,钢试样在酸性土壤浸出液中的腐蚀电流密度为9.6μA/cm~2;当施加10 A/m~2的交流电后,试样的腐蚀电流密度增大到11.95μA/cm~2;当干扰交流电流密度增大到80 A/m~2时,腐蚀电流密度为未施加交流电试样腐蚀电流密度的2.25倍。质量损失结果进一步验证了电化学测试结果,当干扰交流电流密度增大到80 A/m~2时,腐蚀速率是未施加交流电试样腐蚀速率的3.5倍。X80钢在酸性土壤环境中主要发生点蚀,交流杂散电流进一步加速了X80钢的点蚀。结论交流电的引入影响了X80钢的电化学腐蚀过程,交流电正半周期钢试样发生氧化反应,而在负半周期钢试样表面发生还原反应。在整个交流电作用的过程中,交流电正半周期的阳极氧化作用远大于负半周期的阴极还原作用。 相似文献
76.
77.
78.
Ahmad Kalbasi Ashtari Amir M. Samani Majd Gerald L. Riskowski Saqib Mukhtar Lingying Zhao 《Frontiers of Environmental Science & Engineering》2016,10(6):3
Slightly acidic solutions are a practical means of removing ammonia from air
Scrubbed NH3 accumulates in solution as NH4+ and should be an excellent fertilizer
Increased air velocity decreased NH3 removal and increased NH4+ collection
Previous research on wet scrubbers has only studied highly acidic scrubbing solutions because of their high ammonia capture efficiencies; however, the high acidity created practical problems. Lower acidity solutions would reduce corrosion, maintenance, and cost; however, designers may need to use strategies for increasing scrubber effectiveness, such as using lower air velocities. The objective of this study was to determine if a spray scrubber with slightly acidic and higher pH scrubbing solution (pH from 2 to 8) could effectively remove NH3 from NH3 laden air (such as animal building exhaust air), and also collect this valuable resource for later use as a fertilizer. A bench-scale spray wet scrubber treated 20 ppmv NH3/air mixture in a countercurrent contact chamber. First, the solution pH was varied from 2 to 8 while maintaining constant air velocity at 1.3 m·s−1. Next, air velocity was increased (2 and 3 m·s−1) while solution pH remained constant at pH6. At 1.3 m·s−1, NH3 removal efficiencies ranged between 49.0% (pH8) and 84.3% (pH2). This study has shown that slightly acidic scrubbing solutions are a practical means of removing ammonia from air especially if the scrubber is designed to increase collisions between solution droplets and NH3 molecules. The NH3 removed from the air was held in solution as NH4+ and accumulates over time so the solution should be an excellent fertilizer. 相似文献
79.
pH值是衡量降水酸性的重要指标。本文研究了都匀市降水pH值的变化趋势,并对其酸性降水的特征进行分析,提出了保护大气质量,降低酸雨频率的对策建议。 相似文献
80.
ATR-FTIR and XPS study on the structure of complexes formed upon the adsorption of simple organic acids on aluminum hydroxide 总被引:2,自引:0,他引:2
Information on the binding of organic ligands to metal (hydr)oxide surfaces is useful for understanding the adsorption behaviour of natural organic matter on metal (hydr)oxide. In this study, benzoate and salicylate were employed as the model organic ligands and aluminum hydroxide as the metal hydroxide. The attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra revealed that the ligands benzoate and salicylate do coordinate directly with the surface of hydrous aluminum hydroxide, thereby forming innersphere surface complexes. It is concluded that when the initial pH is acidic or neutral, monodentate and bridging complexes are to be formed between benzoate and aluminum hydroxide while bridging complexes predominate when the initial pH is alkalic. Monodentate and bridging complexes can be formed at pH 5 while precipitate and bridging complexes are formed at pH 7 when salicylate anions are adsorbed on aluminum hydroxide. The X-ray photoelectron (XP) spectra demonstrated the variation of C 1 s binding energy in the salicyate and phenolic groups before and after adsorption. It implied that the benzoate ligands are adsorbed through the complexation between carboxylate moieties and the aluminum hydroxide surface, while both carboxylate group and phenolic group are involved in the complexation reaction when salicylate is adsorbed onto aluminum hydroxide. The information offered by the XPS confirmed the findings obtained with ATR-FTIR. 相似文献