全文获取类型
收费全文 | 10260篇 |
免费 | 423篇 |
国内免费 | 908篇 |
专业分类
安全科学 | 1254篇 |
废物处理 | 836篇 |
环保管理 | 1253篇 |
综合类 | 6445篇 |
基础理论 | 372篇 |
污染及防治 | 1173篇 |
评价与监测 | 189篇 |
社会与环境 | 18篇 |
灾害及防治 | 51篇 |
出版年
2024年 | 21篇 |
2023年 | 50篇 |
2022年 | 82篇 |
2021年 | 145篇 |
2020年 | 141篇 |
2019年 | 177篇 |
2018年 | 60篇 |
2017年 | 126篇 |
2016年 | 220篇 |
2015年 | 278篇 |
2014年 | 625篇 |
2013年 | 401篇 |
2012年 | 392篇 |
2011年 | 479篇 |
2010年 | 365篇 |
2009年 | 420篇 |
2008年 | 556篇 |
2007年 | 690篇 |
2006年 | 507篇 |
2005年 | 600篇 |
2004年 | 549篇 |
2003年 | 642篇 |
2002年 | 653篇 |
2001年 | 496篇 |
2000年 | 543篇 |
1999年 | 363篇 |
1998年 | 398篇 |
1997年 | 223篇 |
1996年 | 192篇 |
1995年 | 215篇 |
1994年 | 181篇 |
1993年 | 211篇 |
1992年 | 199篇 |
1991年 | 164篇 |
1990年 | 147篇 |
1989年 | 77篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
城镇污水厂污泥处理处置技术政策探讨 总被引:1,自引:0,他引:1
通过对《城镇污水处理厂污泥处理处置及污染防治技术政策(试行)》提出的各种污泥处理处置方式进行技术和经济可行性分析,评述其可操作性。认为含水率80%的污泥集中处理处置设施不宜采用厌氧消化、堆肥、填埋和热干化技术,实行污泥在污水厂内脱水至含水率60%以下是污泥处理处置节能减排最有效的措施。 相似文献
72.
73.
74.
超声处理对剩余污泥的粒径和溶出物的影响 总被引:12,自引:1,他引:11
为了有效地发挥微型动物摄食对剩余污泥的减量作用,研究了超声声能密度和超声时间对剩余污泥的粒径和溶出物(蛋白质、多糖、DNA、COD及BOD)溶出的影响.在脉冲比2:1和超声时间10min的条件下,声能密度为0.2W·mL-1时出现一个污泥粒径变化的转折点,当小于转折点时污泥粒径随声能密度增加明显下降,而当大于转折点时污泥粒径几乎不受声能密度影响.在脉冲比2:1和声能密度0.8W·mL-1的条件下,超声时间5min是个转折点.上清液中溶出物的浓度随超声波声能密度或超声时间的增加而增加,各溶出物指标之间存在显著的相关关系.溶出物指标中蛋白质指标可以较好地反映出污泥破解状态.为了得到既能使污泥粒径变小到微型动物可摄食的程度又能使污泥中溶出物的溶出量最少的效果,建议声能密度或超声时间取上述转折点为限值.个数平均粒径(Dn)和重量平均粒径(Dw)分别反映了污泥的几何粒径变化和溶出物的溶出状况,因此,在超声破解污泥-微型动物摄食污泥的污泥减量工艺中可通过Dn和Dw的并用来决定剩余污泥超声处理的工艺参数. 相似文献
75.
Enzymes play essential roles in the biological processes of sludge treatment. In this article, the ultrasound method to extract enzymes from sludge flocs was presented. Results showed that using ultrasound method at 20 kHz could extract more types of enzymes than that ultrasound at 40 kHz and ethylenediamine tetraacetic acid (EDTA) methods. The optimum parameters of ultrasound extraction at 20 kHz were duration of 10 min and power of 480 W. Under the condition, ultrasound could break the cells and extract both the extracellular and intercellular enzymes. Ultrasound power was apparently more susceptive to enzyme extraction than duration, suggesting that the control of power during ultrasound extraction was more important than that of duration. The Pearson correlation analysis between enzyme activities and cation contents revealed that the different types of enzymes had distinct cation binding characteristics. 相似文献
76.
A novel biphenyl-degrading bacterial strain LA-4 was isolated from activated sludge. It was identified as Dyella ginsengisoli according to phylogenetic similarity of 16S rRNA gene sequence. This isolate could utilize biphenyl as sole source of carbon and energy, which degraded over 95 mg/L biphenyl within 36 h. The major metabolites formed from biphenyl, such as 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid (HOPDA) and benzoic acid, were identified by LC-MS. The crude cell extract of strain LA-4 exhibited the activity of 2,3-dihydroxybiphenyl 1,2-dioxygenase (2,3-DHBD) and the kinetic parameters were Km= 26.48 μmol/L and Vmax= 8.12 μmol/mg protein. A conserved region of the biphenyl dioxygenase gene bphA1 of strain LA-4 was amplified by PCR and confirmed by DNA sequencing. 相似文献
77.
Alkaline and ultrasonic sludge disintegration can both be used as pretreatments of waste activated sludge (WAS) for improving the subsequent anaerobic or aerobic digestion. The pretreatment has been carried out using different combination of these two methods in this study. The effect was evaluated based on the quantity of soluble chemical oxygen demand (SCOD) in the pretreated sludge as well as the degradation of organic matter in the following aerobic digestion. For WAS samples with combined pretreatment, the released COD was in high level than those with ultrasonic or alkaline treatment. When combined with the same ultrasonic treatment, NaOH treatment resulted in more solubilization of WAS than Ca(OH)2. For combined NaOH and ultrasonic treatments with different sequences, the released COD were in the order: simultaneous treatment > ultrasonic treatment following NaOH treatment > NaOH treatment following ultrasonic treatment. For simultaneous treatment, low NaOH dosage (100 g/kg dry solid), short duration (30 min) of NaOH treatment, and low ultrasonic specific energy (7 500 kJ/kg dry solid) were beneficial for sludge disintegration. Using combined NaOH and ultrasonic pretreatment with the optimium parameters, the degradation efficiency of organic matter was increased from 38.0% to 50.7%, which is much higher than with ultrasonic (42.5%) or with NaOH pretreatment (43.5%) in the subsequent aerobic digestion at the same retention time. 相似文献
78.
A bacterial strain that utilized o-chloronitrobenzene(o-CNB) as the sole carbon,nitrogen and energy sources was isolated from an activated sludge collected from an industrial waste treatment plant. It was identified as Pseudomonas putida based on its morphology,physiological,and biochemical characteristics with an automatic biometrical system and the 16S rRNA sequence analysis. Microcosm study showed that the biodegradation of o-CNB was optimized at culture medium pH 8.0 and 32°C. At these conditions,the st... 相似文献
79.
化学强化一级处理-人工湿地处理生活污水效果 总被引:6,自引:1,他引:5
为解决传统的污水二级生化处理工艺运行成本较高问题并满足日趋增长的小城镇污水处理实际需要,开展了粉煤灰基混凝剂化学强化一级处理—潜流式人工湿地(CEPT-SFCW)系统处理生活污水的实验研究。结果表明,在人工湿地负荷率为0.05~0.1m3/(m·2d)的条件下,CEPT-SFCW系统对COD的去除率>85%。同时,CEPT-SFCW系统对总磷的去除率很高,虽然在进水含磷量低时人工湿地会发生磷释放的现象,出水中磷浓度仍可达到GB8978-1996中的二级排放标准。该系统对氨氮去除效率较低,最高可达到10%,去除效果与植物的生长状态有关。 相似文献
80.