全文获取类型
收费全文 | 307篇 |
免费 | 46篇 |
国内免费 | 240篇 |
专业分类
安全科学 | 36篇 |
废物处理 | 27篇 |
环保管理 | 23篇 |
综合类 | 313篇 |
基础理论 | 105篇 |
污染及防治 | 82篇 |
评价与监测 | 3篇 |
社会与环境 | 4篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 8篇 |
2021年 | 18篇 |
2020年 | 11篇 |
2019年 | 19篇 |
2018年 | 26篇 |
2017年 | 32篇 |
2016年 | 29篇 |
2015年 | 29篇 |
2014年 | 30篇 |
2013年 | 56篇 |
2012年 | 30篇 |
2011年 | 27篇 |
2010年 | 26篇 |
2009年 | 25篇 |
2008年 | 30篇 |
2007年 | 31篇 |
2006年 | 20篇 |
2005年 | 19篇 |
2004年 | 17篇 |
2003年 | 14篇 |
2002年 | 8篇 |
2001年 | 17篇 |
2000年 | 5篇 |
1999年 | 9篇 |
1998年 | 7篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
排序方式: 共有593条查询结果,搜索用时 109 毫秒
121.
The aim of this study was to evaluate the suitability of in vitro enzymatic methods for assaying the biodegradability of new starch-based biopolymers. The materials studied included commercial starch-based materials and thermoplastic starch films prepared by extrusion from glycerol and native potato starch, native barley starch, or crosslinked amylomaize starch. Enzymatic hydrolysis was performed using excessBacillus licheniformis -amylase andAspergillus niger glucoamylase at 37°C and 80°C. The degree of degradation was determined by measuring the dissolved carbohydrates and the weight loss of the samples. Biodegradation was also determined by incubating the samples in a compost environment and measuring the weight loss after composting. The results indicated that the enzymatic method is a rapid means of obtaining preliminary information about the biodegradability of starch-based materials. Other methods are needed to investigate more accurately the extent of biodegradability, especially in the case of complex materials in which starch is blended with other polymers. 相似文献
122.
123.
石化厂皂化废水的厌氧处理 总被引:2,自引:0,他引:2
石化厂以氯醇法生产环氧乙烷过程中排出的皂化废水有机物含量高、含盐量高,并呈强碱性.废水中的物质对厌氧微生物产生强烈的抑制.本工艺通过预处理,减轻了抑制程度.采用厌氧工艺作为主要处理工艺,在水力停留时间≥4天,有机容积负荷COD_(Cr)小于2.0kg/m~3·d的条件下,取得了较好的厌氧处理效果.补充好氧接触氧化法作后处理,出水水质满足排放要求. 相似文献
124.
联苯胺对碱性磷酸酶抑制作用及其动力学研究 总被引:4,自引:0,他引:4
联苯胺作为一种危害严重对环境污染物,对小牛肠碱性磷酸酶的酶活力有明显的抑制作用。这种抑制随着联苯胺浓度的增加而增强,当联苯胺浓度>1.0μg/L时,其抑制程度趋于恒定。运用酶活力研究的动力学模型,在不同的酶底物浓度及不同的抑制剂浓度下,用分光光度法监测酶底物水解产物浓度随时间变化的过程,研究了抑制剂联苯胺对小牛肠碱性磷酸酶活性的抑制动力学,结果表明,联苯胺对小牛肠碱性磷酸酶的抑制是可逆抑制,属于可逆抑制中的竞争性抑制类型;求得其抑制剂常数Ki为1.28×10-7mol/L。 相似文献
125.
应用静态试验,研究了As(Ⅲ),As(Ⅴ)对活性污泥脱氢酶活性、脲酶活性、蛋白酶活性的影响。其结果:抑制10%脱氢酶、脲酶、蛋白酶活性的As(Ⅲ)浓度分别为10.0mg/gMLSS,13.4mg/gMLSS,2.6mg/gMLSS;As(Ⅴ)的浓度则分别为552.6mg/gMLSS,464.4mg/gMLSS,193.7mg/gMLSS。As(Ⅲ)对活性污泥的毒性比As(Ⅴ)平均大53倍。 相似文献
126.
细菌产绿脓菌素对东海原甲藻生长的影响 总被引:1,自引:0,他引:1
以东海原甲藻(Prorocentrumdonghaiense)为实验材料,研究了铜绿假单胞菌(Pseudomonasaeruginosa)产绿脓菌素对藻细胞生长的影响。结果表明,当其浓度达到5.0mg.L-1时,对东海原甲藻的生长表现出明显的抑制效果,并且抑制效果随浓度的增加而增强。对裸甲藻而言,当其浓度增加至15.0mg.L-1时,裸甲藻的生长才开始受到较明显的抑制。8.0和15.0mg.L-1的绿脓菌素在实验初期对湛江叉鞭金藻的生长表现出了一定的抑制作用,但这种抑制作用不能持久。对绿藻而言,即使浓度增加至15.0mg.L-1,绿藻的生长受其影响也很弱。本文首次探讨了细菌产绿脓菌素对东海原甲藻的抑制作用,结果表明该类物质可以选择性的抑制东海原甲藻的生长。 相似文献
127.
以活性污泥脱氢酶的活性作为毒性指标,研究了半导体材料GaAs、Ga~(3+)、Ge~(4+)对活性污泥活性的抑制影响,并用Hg~(2+)作为参比材料;同时对抑制动力学也作了初步研究。实验表明,GaAs、Ga~(3+)、Ge~(4+)及Hg~(2+)的10%抑制浓度分别为45.00,371.63,0.13ppm/gMLSS,GaAs、Ga~(3+)、Ge~(4+)和Hg~(2+)在浓度分别为180,700,250和1.25ppm/g MLSS时的抑制常数分别为1.30×10~(-3),7.05×10~(-3),6.12×10~(-3)和5.49×10~(-3)mmol,且其抑制类型均属可逆非竞争性抑制。 相似文献
128.
Summary Glycosidase inhibitors are widespread in plants and can be sequestered by Lepidoptera, for which they can presumably serve as defences by making the insects indigestible to a range of potential predators. As a result of this study of eight British species of moth and butterfly it was found that glycosidase inhibitors in the insects could then be detected in the larval food plants which were not previously known to contain them; however, some were only detectable in the plants after concentration. In some cases the inhibition of specific glycosidases by Lepidoptera was detected even though the insects had not apparently acquired them from their food plants. Inhibition of-N-acetylglucosaminidase was observed in most of the adult Lepidoptera analysed but further work is required to identify the inhibitors, though they are likely to be nitrogen-containing compounds. Weak anti-HIV activity was also observed in the glycosidase-inhibiting fractions ofAcherontia atropos and the plantUrtica dioica. 相似文献
129.
130.
Almeida CM Mucha AP Vasconcelos MT 《Environmental science and pollution research international》2005,12(5):271-277
Goal, Scope and Background The presence or absence of vegetation can condition sediment characteristics. The main aim of this work was to investigate
the influence of the sea rush Juncus maritimus on metal (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) availability to organisms living
on or in estuarine sediments, from Douro River (NW Portugal), by comparing the characteristics and chemical behaviour of rhizosediments
(collected within the plant assemblage) and those of sediment (collected around the plant). In order to evaluate whether and
how sediment characteristics condition the role of plants on metal availability, sandy and muddy sediments colonised by J.
maritimus were studied in parallel.
Methods Metal availability was estimated by enzymatic digestion with pepsin (ED), which may provide an estimate of metal availability
to organisms living at estuarine sediments. Nevertheless, since no consensus exists yet on the most suitable methodologies
to estimate metal bioavailability in sediments, two more conventional approaches, BCR sequential extraction (SE) and AVS/SEM
model, were also used, in parallel, and the information these approaches provided was compared with that provided by ED. Total-recoverable
metal contents were determined by atomic absorption spectrophotometry after sediment digestion using a high-pressure microwave
system.
Results and Discussion Plants could concentrate metals around its roots and rhizomes. In addition, they were capable of oxidizing (release of oxygen
by the roots) the anaerobic medium surrounding their roots in muddy sediment (reducing AVS). As sulphide oxidation renders
metals (Cd, Cu, Ni, Pb and Zn) into more soluble forms, according to the AVS/SEM model, metals from muddy sites would be more
available in rhizosediment than in sediment. The SE approach led to a similar conclusion. Nevertheless, the results provided
by ED pointed at opposite conclusion, particularly for Cd and Zn, indicating less availability at rhizosediments than in the
surrounding sediment. ED results were interpreted as a consequence of an enrichment of the rhizosediment in organic ligands
exuded by the roots or liberated by dead plants. The effect of complexation of metals by organic compounds, which ED could
not decompose/dissolve, seemed to overcome that caused by sediment oxidation. In general, a comparison of the information
about metal availability by ED, SE, AVS/SEM, showed that it did not always match and in few cases it was even contradictory.
Conclusion and Outlook Therefore, a thorough evaluation of the metal availability in sediments requires a combination of different chemical approaches,
so as to take into consideration differences in ways of organism exposure (interstitial water and/or ingestion of sediment
particles).
- * The basis of this peer-reviewed paper is a presentation at the 9th FECS Conference on 'Chemistry and Environment', 29 August
to 1 September 2004, Bordeaux, France. 相似文献