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   602篇
  免费   59篇
  国内免费   510篇
安全科学   30篇
废物处理   122篇
环保管理   38篇
综合类   648篇
基础理论   150篇
污染及防治   178篇
评价与监测   4篇
社会与环境   1篇
  2023年   3篇
  2022年   10篇
  2021年   16篇
  2020年   9篇
  2019年   13篇
  2018年   18篇
  2017年   21篇
  2016年   37篇
  2015年   26篇
  2014年   40篇
  2013年   91篇
  2012年   71篇
  2011年   64篇
  2010年   54篇
  2009年   64篇
  2008年   55篇
  2007年   73篇
  2006年   114篇
  2005年   57篇
  2004年   49篇
  2003年   51篇
  2002年   37篇
  2001年   33篇
  2000年   27篇
  1999年   31篇
  1998年   28篇
  1997年   15篇
  1996年   21篇
  1995年   15篇
  1994年   8篇
  1993年   11篇
  1992年   1篇
  1991年   5篇
  1989年   2篇
  1986年   1篇
排序方式: 共有1171条查询结果,搜索用时 15 毫秒
921.
Laboratory evidence of MTBE biodegradation in Borden aquifer material   总被引:16,自引:0,他引:16  
Mainly due to intrinsic biodegradation, monitored natural attenuation can be an effective and inexpensive remediation strategy at petroleum release sites. However, gasoline additives such as methyl tert-butyl ether (MTBE) can jeopardize this strategy because these compounds often degrade, if at all, at a slower rate than the collectively benzene, toluene, ethylbenzene and the xylene (BTEX) compounds. Investigation of whether a compound degrades under certain conditions, and at what rate, is therefore important to the assessment of the intrinsic remediation potential of aquifers. A natural gradient experiment with dissolved MTBE-containing gasoline in the shallow, aerobic sand aquifer at Canadian Forces Base (CFB) Borden (Ontario, Canada) from 1988 to 1996 suggested that biodegradation was the main cause of attenuation for MTBE within the aquifer. This laboratory study demonstrates biologically catalyzed MTBE degradation in Borden aquifer-like environments, and so supports the idea that attenuation due to biodegradation may have occurred in the natural gradient experiment. In an experiment with batch microcosms of aquifer material, three of the microcosms ultimately degraded MTBE to below detection, although this required more than 189 days (or >300 days in one case). Failure to detect the daughter product tert-butyl alcohol (TBA) in the field and the batch experiments could be because TBA was more readily degradable than MTBE under Borden conditions.  相似文献   
922.
苯乙烯生物滴滤塔生物膜填料的细菌数量分布   总被引:1,自引:0,他引:1  
采用培养驯化污泥菌种、陶粒、循环液装置等构建三个生物滴滤塔。测定不同苯乙烯负荷生物滴滤塔装置不同高度生物膜填料的细菌数量分布,认识苯乙烯浓度对填料细菌数量分布的影响。结果表明,生物膜填料柱细菌数量分布依赖于入口气体苯乙烯浓度和停留时间,在低入口气体苯乙烯浓度(Cin<500mg/m3)时细菌数在柱子底部达到最大值而沿柱子自下而上逐渐降低,受气体停留时间的影响不大;当入口气体苯乙烯浓度Cin=800mg/m3时细菌数在整个柱子上的分布变得相对均匀;而当入口气体苯乙烯浓度超过阈限值Cin=1200mg/m3时细菌分布行为出现了和Cin<500mg/m3时相反的情况,细菌数在柱子顶部达到最大值而沿柱子自上而下逐渐降低。  相似文献   
923.
氯代有机物生物降解研究进展   总被引:3,自引:1,他引:2  
综述了氯代有机物的降解机理、降解影响的因素和目前国内外研究较为活跃的几种生物降解新技术:化学、物理与生物联合处理技术、利用共代谢降解氯代有机物、基因工程菌技术、细胞固定化技术和膜生物反应器处理技术的研究进展,并提出了今后值得关注的几个方向。  相似文献   
924.
More than 100 t of nitrobenzene (NB) and related compounds were discharged into the Songhua River, the fourth longest river in China, because of the world-shaking explosion of an aniline production factory located in Jilin City on November 13, 2005. As one of the efforts to predict the fate of residual NB in the river, NB biodegradation abilities of the microbes in the water and sediments from different river sections were evaluated systematically. The results indicated that microbial communities from any section of the river, including one section at the upper stream of the NB discharging point, had the ability to biodegrade NB under aerobic (for river water samples) conditions at 22±1℃ or anaerobic (for sediment samples) conditions at 10±1℃. NB degradation rates of microbial communities in the downstream sites were markedly higher than those in the upstream site, indicating that the NB degradation abilities were enhanced because of the pollution of NB. Aerobic degradation got neglected at a temperature of 10℃ or lower. The production of nitrosobenzene and aniline during the aerobic biodegradation suggested the existence of at least two different NB degradation pathways, and the occurrence of the catechol-2,3-dioxygenase (C23O) gene and the significant decrease of dissolved organic carbon (DOC) indicated that NB could be mineralized under aerobic conditions. Although it was a fact that the river have frozen-up during the NB accident, it was speculated that biodegradation was not the major process responsible for the decrease of NB flux in the river.  相似文献   
925.
Nonylphenol ethoxylate (NPEO)-degrading bacteria were isolated from activated sludge using an improved isolation method, and the corresponding degradation behaviours were investigated. Eight NPEO-degrading strains distributed in genera Pseudomonas, Sphingomonas, Sphingobium, Cupriavidus, Ralstonia, Achromobacter, and Staphylococcus were acquired. The latter five genera have never been reported for the degradation of NPEOs. Four degradation patterns were observed for the eight pure strains. In pattern A, NPE...  相似文献   
926.
Bioremediation is a proven alternative for remediating petroleum‐impacted soils at exploration and production (E&P) sites. Monitoring remediation performance can involve detection and quantification of biodegradation resistant compounds such as C3017α(H),21β(H)‐hopane, which requires the use of gas chromatography with mass spectrometry detection (GC/MS). Due to the remoteness of many E&P sites, this technology is not always available, and alternative methods are needed to provide reliable quantitative measurements of petroleum remediation efficiency. This study provides a detailed chemical characterization of lacustrine‐sourced crude oils and a technical basis for measuring the effectiveness of bioremediation efforts for soil impacted by those crudes. We show that the novel isoprenoid hydrocarbon botryococcane is relatively stable in lacustrine‐sourced crude oils compared with C3017α(H),21β(H)‐hopane under moderate biodegradation conditions generally observed in field samples. We have also demonstrated that, due to the stability and relatively elevated concentration of botryococcane in lacustrine oils, it can be reliably measured using the more cost‐effective and available GC/FID methodology, and thereby be used to monitor the progress of ongoing soil bioremediation activities at remote sites.  相似文献   
927.
Elongation properties of extruded cornstarch were improved by blending with glycerol. Further blending of starch-glycerol with polyvinyl alcohol (PVOH) resulted in significant improvements in both tensile strength (TS) and elongation at break. Samples of starch-glycerol without PVOH equilibrated at 50% relative humidity had a TS of 1.8 MPa and elongation of 113%, whereas those containing PVOH had a TS and elongation of 4 MPa and 150%, respectively. Dynamic mechanical analysis (DMA) of starch-glycerol-PVOH blends showed that decreases in glass transition temperatures (T g values) were proportional to glycerol content. Scanning electron microscopy (SEM) of fractured surfaces revealed numerous cracks in starch-glycerol (80:20) samples. Cracks were absent in starch-glycerol (70:30) samples. In both blends, many starch granules were exposed at the surface. No exposed starch granules were visible in blends with added PVOH. Starch-glycerol samples incubated in compost lost up to 70% of their dry weight within 22 days. Addition of PVOH lowered both the rate and extent of biodegradation.  相似文献   
928.
The degradation of two kinds of polyion complex (PIC) fibers, chitosan-gellan (CGF), and poly(L-lysine)-gellan (LGF) fibers, by seven species of soil filamentous fungi has been investigated. All of the pure-line soil filamentous fungi, Aspergillus oryzae, Penicillium caseicolum, P. citrinum, Mucor sp., Rhizopus sp., Curvularia sp., and Cladosporium sp. grew on the two fiber materials. Microscopic observation of the biodegradation processes revealed that P. caseicolum on the CGF and LGF grew, along with the accompanying collapse of the fiber matrices. In the biochemical oxygen-demand (BOD) test, the biodegradation of the LGF by P. caseicolum and Curvularia sp. exceeded 97% carbon dioxide generation and the biodegradation of the CGF by A. oryzae was 59%. These results might offer some clues to the applications of the PIC fibers as environmentally biodegradable materials.  相似文献   
929.
厌氧颗粒污泥对五氯酚(PCP)的吸附、解吸及生物降解   总被引:5,自引:0,他引:5  
以未驯化污泥接种的升流式厌氧污泥床反应器可形成降解五氯酚(PCP)的颗粒污泥.颗粒污泥去除PCP的主要机制是生物降解作用,而不是生物吸附作用.PCP在颗粒污泥上的吸附和解吸符合Freundlich等温方程,吸附和解吸的Freundlich常数K、1/n分别为0.7857mg/gSS、0.5079和1.1095mg/gSS、0.3782,部分PCP被不可逆吸附.与其它活或死的生物材料相比,本试验形成的颗粒污泥对PCP吸附量较小.该方程较准确地表达了UASB反应器内厌氧颗粒污泥对PCP吸附量的变化规律.  相似文献   
930.
Interest in coupled biodegradation and transport of organic contaminants has expanded greatly in the past several years. In a system in which biodegradation is coupled with solute transport, the magnitude and rate of biodegradation is influenced not only by properties of the microbial population and the substrate, but also by hydrodynamic properties (e.g., residence time, dispersivity). By nondimensionalizing the coupled-process equations for transport and nonlinear biodegradation, we show that transport behavior is controlled by three characteristic parameters: the effective maximum specific growth rate, the relative half-saturation constant, and the relative substrate-utilization coefficient. The impact on biodegradation and transport of these parameters, which constitute various combinations of factors reflecting the influences of biotic and hydraulic properties of the system, are examined numerically. A type-curve diagram based on the three characteristic parameters is constructed to illustrate the conditions under which steady and non-steady transport is observed, and the conditions for which the linear, first-order approximation is valid for representing biodegradation. The influence of constraints to microbial growth and substrate utilization on contaminant transport is also briefly discussed. Additionally, the impact of biodegradation, with and without biomass growth, on spatial solute distribution and moments is examined.  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