全文获取类型
收费全文 | 280篇 |
免费 | 25篇 |
国内免费 | 181篇 |
专业分类
安全科学 | 8篇 |
废物处理 | 40篇 |
环保管理 | 20篇 |
综合类 | 266篇 |
基础理论 | 64篇 |
污染及防治 | 87篇 |
社会与环境 | 1篇 |
出版年
2023年 | 3篇 |
2022年 | 6篇 |
2021年 | 2篇 |
2020年 | 7篇 |
2019年 | 14篇 |
2018年 | 12篇 |
2017年 | 9篇 |
2016年 | 18篇 |
2015年 | 21篇 |
2014年 | 26篇 |
2013年 | 39篇 |
2012年 | 34篇 |
2011年 | 30篇 |
2010年 | 19篇 |
2009年 | 16篇 |
2008年 | 20篇 |
2007年 | 18篇 |
2006年 | 33篇 |
2005年 | 25篇 |
2004年 | 17篇 |
2003年 | 11篇 |
2002年 | 19篇 |
2001年 | 14篇 |
2000年 | 9篇 |
1999年 | 12篇 |
1998年 | 9篇 |
1997年 | 10篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1989年 | 1篇 |
1988年 | 1篇 |
排序方式: 共有486条查询结果,搜索用时 156 毫秒
121.
腐殖酸影响剩余污泥厌氧消化过程实验研究 总被引:2,自引:1,他引:1
以实验室培养、几乎不含腐殖质和金属离子的剩余污泥作为研究对象,选择与市政污泥中腐殖酸特征相近的市售腐殖酸为外加填充物,实验研究污泥中所含腐殖质对污泥厌氧消化过程的抑制作用.通过设置腐殖酸不同投加比例(0、5%、10%、15%和20%,以VSS计),探究腐殖酸对厌氧消化不同过程的影响.实验结果表明,腐殖酸抑制厌氧消化生物气产气量.填加15%腐殖酸时对厌氧消化产气量抑制作用最为明显,较未添加腐殖酸对照组产气量下降了35%;但并未对生物气中CH_4体积比产生太大影响,说明抑制影响是对生物气整体性的.腐殖酸亦可抑制厌氧水解过程,投加20%腐殖酸实验组实验结束时残留于上清液中的溶解性多糖、蛋白质浓度分别是对照组的2.2和1.6倍.然而,腐殖酸作为外源电子受体,可以在一定程度上促进酸化过程,其程度在填加20%腐殖酸实验组表现最高,较对照组VFAs提高了11.3%.腐殖酸投加未对系统pH产生明显影响,各实验组pH值均在7.09~7.54间变化. 相似文献
122.
为了研究氮添加对森林土壤有机碳氮组分稳定性的影响,选取我国亚热带典型常绿阔叶林(浙江桂天然林和罗浮栲天然林)和针叶林(杉木人工林),开展为期5年的野外模拟氮沉降试验,分别设置对照〔0 kg/(hm2·a),以NH4NO3中的N计,下同〕、低氮〔75 kg/(hm2·a)〕和高氮〔150 kg/(hm2·a)〕3个氮添加水平,用H2SO4分2步酸水解获得LPⅠ(活性有机库Ⅰ)、LPⅡ(活性有机库Ⅱ)和RP(惰性有机库),定量研究土壤活性和惰性有机碳氮组分以及微生物生物量碳氮对氮添加的响应. 结果表明:氮添加仅对w(LPⅡ-C)(LPⅡ-C为活性有机碳Ⅱ)有显著影响,而对其他活性和惰性有机碳氮组分的影响不显著,并且对不同林分的影响存在差异. 与对照处理相比,低氮处理下浙江桂天然林、罗浮栲天然林和杉木人工林土壤w(LPⅡ-C)的增幅分别为15.3%、29.8%、68.8%;高氮处理下杉木人工林土壤w(LPⅠ-C)(LPⅠ-C为活性有机碳Ⅰ)、w(LPⅠ-N)(LPⅠ-N为活性有机氮Ⅰ)和w(RP-C)(RP-C为惰性有机碳)的增幅分别为32.4%、78.6%、28.7%;氮添加使得土壤w(SMB-C)(土壤微生物生物量碳)的增幅为18.1%~202.5%、w(SMB-N)(土壤微生物生物量氮)的增幅为0%~103.6%;在氮添加处理下,除杉木人工林土壤SMB-N/LPⅠ-N〔w(SMB-N)/w(LPⅠ-N)〕是随着氮添加水平的增加而降低外,微生物对其他林分土壤活性有机氮的利用均表现为随着氮添加水平的增加而增加. 研究显示,氮添加对阔叶林和针叶林土壤活性和惰性有机碳氮组分的影响存在差异,但差异不显著,这与它们归还土壤的凋落物性质差异有关,并且凋落物的分解差异也可能是影响土壤不同碳氮组分变化的原因. 相似文献
123.
124.
125.
Deivis E. Lujan-Rhenals Rubén O. Morawicki Steven C. Ricke 《Journal of environmental science and health. Part. B》2013,48(4):305-311
The objective of this research was to determine the minimum inhibitory concentration of 5-hydroxymethyl furfural, furfural, and acetic acid on Saccharomyces cerevisiae (NRRL Y-2233) and Zymomonas mobilis subspecies mobilis (NRRL B-4286) in both detoxified hydrolyzed soybean meal and synthetic YM broth spiked with the three compounds. Soybean meal was hydrolyzed with dilute sulfuric acid (0.0, 0.5, 1.25, and 2.0% wt v?1) at three temperatures (105, 120, and 135°C) and three durations (15, 30, and 45 min) followed by detoxification with activated carbon. Of all the combinations, only the treatments obtained at 135°C, 2.0% H2SO4, and 45 min and the one at 135°C, 1.25% H2SO4, and 45 min showed inhibition in the growth of the tested microorganisms. Spiked YM broths showed inhibition for the highest levels of inhibitors, either applied individually or in combination. 相似文献
126.
《Environmental Forensics》2013,14(4):239-243
Groundwater contaminated by the gasoline additive methyl tertiary butyl ether (MtBE) is also frequently impacted by tertiary butyl alcohol (tBA). The USEPA recently sponsored a study that discusses the possibility of hydrolysis of MtBE to form tBA during analytical procedures. This finding is important because it suggests that existing tBA data may not accurately depict tBA or MtBE concentrations in groundwater. This article discusses the mechanism and kinetics of MtBE hydrolysis, then presents three case studies of analytical results from sites in California, USA. Although these case studies are limited in scope, the data do not support the occurrence of the hydrolysis of MtBE to form tBA due to acid preservation of groundwater samples. At a minimum, this suggests that MtBE hydrolysis may not be as pervasive a problem as suggested in USEPA's study; therefore, concerns about the validity of historical tBA data may not be warranted. The reason for this result may be simple: there are two necessary factors that promote hydrolysis: low pH and high temperature (above 40°C). Although the static headspace analysis method used to obtain the data in the White et al. study may require heating to achieve adequate sensitivity, many laboratories perform purge-and-trap analyses without heating. Under those conditions, hydrolysis may not occur. However, it may be prudent to preserve samples with alkaline preservatives, to eschew high temperatures during the analysis of groundwater samples, or to neutralize the sample pH before heating. 相似文献
127.
Dibyajyoti Haldar 《International Journal of Green Energy》2018,15(6):406-413
In current work, an optimum solid loading (solid: liquid = 1:20), pH (4.8), temperature (50°C), and enzyme dosing of 20 filter paper unit (amount of enzyme required to release 1 µmol of glucose as reducing sugar from filter paper in per mL per minute) were enumerated for enzymatic hydrolysis of banana stem using cellulase from Trichoderma reesei. Further, inhibition study on enzymatic hydrolysis of banana stem was investigated by the supplementation of monosaccharides (glucose, galactose, mannose, xylose, and arabinose), disaccharide (cellobiose), and inhibitors (acetic acid and furfural obtained from pre-enzymatic hydrolysis steps). Glucose and cellobiose showed inhibitory effect on enzymatic hydrolysis of pretreated banana stem at or above 8 g/L while galactose, mannose, and xylose showed a significant inhibitory effect at or above 4 g/L. Instead of inhibition, arabinose enhanced the enzymatic hydrolysis with increase in total reducing sugars. Acetic acid did not show any significant inhibition while furfural inhibited the system at a comparative low concentration of 2 g/L. Further, scanning electron microscopy analysis was performed to investigate the difference in ultra-structural morphology of raw biomass, pretreated biomass, and biomass obtained after enzymatic hydrolysis. 相似文献
128.
Somsubhra Chakraborty Bhabani S. Das Md. Nasim Ali Bin Li M.C. Sarathjith K. Majumdar D.P. Ray 《Waste management (New York, N.Y.)》2014,34(3):623-631
The aim of this study was to investigate the feasibility of using visible near-infrared (VisNIR) diffuse reflectance spectroscopy (DRS) as an easy, inexpensive, and rapid method to predict compost enzymatic activity, which traditionally measured by fluorescein diacetate hydrolysis (FDA-HR) assay. Compost samples representative of five different compost facilities were scanned by DRS, and the raw reflectance spectra were preprocessed using seven spectral transformations for predicting compost FDA-HR with six multivariate algorithms. Although principal component analysis for all spectral pretreatments satisfactorily identified the clusters by compost types, it could not separate different FDA contents. Furthermore, the artificial neural network multilayer perceptron (residual prediction deviation = 3.2, validation r2 = 0.91 and RMSE = 13.38 μg g?1 h?1) outperformed other multivariate models to capture the highly non-linear relationships between compost enzymatic activity and VisNIR reflectance spectra after Savitzky–Golay first derivative pretreatment. This work demonstrates the efficiency of VisNIR DRS for predicting compost enzymatic as well as microbial activity. 相似文献
129.
通过静态和动态连续降解实验,揭示了壬基酚聚氧乙烯醚(NPEO,Nonylphenol ethoxylates,浓度6.25~12.5 mg·L-1)在碱性牛仔布印染废水中的去除规律.批式活性污泥实验表明,厌氧环境下,随着p H值的增加,壬基酚(NP,Nonylphenol)产生受到抑制,短链NPEO(环氧乙烯加成数1~3,NP(1~3)EO)总浓度水平虽然只有500~900μg·L-1,却呈现增加趋势;好氧环境下,尽管NPEO总量降解率超过85%,但产生的各种短链NP(1~3)EO和短链壬基酚聚氧乙烯醚酸酯(NPEC,Nonylphenol polyethoxycarboxylate)浓度区间为10~110μg·L-1,碱性环境下两类物质总量最低,不足100μg·L-1.耦合厌氧水解和好氧曝气的连续实验表明,增设填料的厌氧折板水解池出水中短链NP(1~3)EO的总浓度增至4000~5000μg·L-1,这与厌氧环境下一部分NPEO附着在废水杂质和厌氧污泥上,在污泥龄较长的附着型污泥作用下,生成了大量的NP(1~3)EO有关;好氧段出水中NP(1~3)EO浓度降至230~610μg·L-1,短链NPEC(NP(1~3)EC)总量上升到800~1000μg·L-1,NP(1~3)EC由NP(1~3)EO转化来的可能最大.印染出水中NP及NP(1~3)EO受厌氧段出水中NP及NP(1~3)EO浓度影响明显. 相似文献
130.