全文获取类型
收费全文 | 953篇 |
免费 | 67篇 |
国内免费 | 465篇 |
专业分类
安全科学 | 65篇 |
废物处理 | 45篇 |
环保管理 | 130篇 |
综合类 | 750篇 |
基础理论 | 255篇 |
环境理论 | 1篇 |
污染及防治 | 176篇 |
评价与监测 | 34篇 |
社会与环境 | 26篇 |
灾害及防治 | 3篇 |
出版年
2024年 | 2篇 |
2023年 | 23篇 |
2022年 | 46篇 |
2021年 | 44篇 |
2020年 | 49篇 |
2019年 | 70篇 |
2018年 | 75篇 |
2017年 | 58篇 |
2016年 | 77篇 |
2015年 | 64篇 |
2014年 | 79篇 |
2013年 | 135篇 |
2012年 | 75篇 |
2011年 | 75篇 |
2010年 | 61篇 |
2009年 | 71篇 |
2008年 | 69篇 |
2007年 | 48篇 |
2006年 | 48篇 |
2005年 | 29篇 |
2004年 | 18篇 |
2003年 | 53篇 |
2002年 | 26篇 |
2001年 | 29篇 |
2000年 | 28篇 |
1999年 | 13篇 |
1998年 | 12篇 |
1997年 | 11篇 |
1996年 | 8篇 |
1995年 | 23篇 |
1994年 | 15篇 |
1993年 | 8篇 |
1992年 | 9篇 |
1991年 | 8篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1979年 | 1篇 |
排序方式: 共有1485条查询结果,搜索用时 296 毫秒
101.
膜生物反应器(MBR)是一种高效的污水处理工艺,而微生物燃料电池(MFC)能有效降解污泥中的胞外生物有机质(EBOM)并回收电能.将MFC与MBR联用,建立了一套能够有效抑制膜污染同时回收电能的新系统——MFC-MBR耦合系统,MBR的剩余污泥经MFC处理后回流.以传统MBR为对照,对耦合系统中污水处理效果、膜污染情况和污泥混合液的性质进行研究.研究表明,耦合系统的污水处理效果没有明显恶化,COD去除率为94%,NH4+-N的去除率为92%.耦合系统能够有效减缓膜污染的发生,清洗周期延长了28%.污泥混合液的MLVSS/MLSS稳定在80% ~ 88%,系统内几乎没有无机颗粒积累.松散结合态胞外聚合物(LB-EPS)降低了48%,使污泥混合液性质得到改善.较低的污泥比阻(2.69×1012m/kg)和标准化毛细吸水时间(1.67 s·L/g MLSS),证明耦合系统污泥混合液脱水性能提高了. 相似文献
102.
Effect of microbial siderophore DFO-B on Cd accumulation by Thlaspi caerulescens hyperaccumulator in the presence of zeolite 总被引:1,自引:0,他引:1
Hyperaccumulators are grown in contaminated soil and water in order that contaminants are taken up and accumulated. Transport of metals from soil to plant is initially dependent on the solubility and mobility of metals in soil solution which is controlled by soil and metal properties and plant physiology. Complexation with organic and inorganic ligands may increase mobility and availability of metals for plants. In this work the influence of desferrioxamine-B (DFO-B), which naturally is produced in the rhizosphere, and zeolite on Cd accumulation in root and shoot of Thlaspi caerulescens (Cd hyperaccumulator) was investigated. Plants were grown in pots with clean quartz sand, amended with 1% zeolite; treatment solutions included 0, 10, and 100 μM Cd and 70 μM DFO-B. Addition of zeolite to the quartz sand significantly reduced Cd concentration in plant tissues and translocation from root to shoot. On contrary, DFO-B considerably enhanced Cd sorption by roots and translocation to aerial part of plants. Treating the plants with zeolite and DFO-B together at 10 μM Cd resulted in reduction of the bioaccumulation factor but enhancement of Cd translocation from root to shoot at the rate of 13%. In contrast, at 100 μM Cd in the solution both bioaccumulation and translocation factors decreased. Total metal accumulation as a key factor for evaluating the efficiency of phytoremediation was highly influenced by treatments. Presence of zeolite in pots significantly decreased total Cd accumulation by plants, whereas, DFO-B clearly enhanced it. 相似文献
103.
This paper presents a theoretical comparison between fuel cell (FC) power train and conventional petrol driven propulsion system. FC has potential to reduce the CO2-emissions from road. However, FC power trains require energy storing device, to meet the peak power during extreme drive situations and also able to recover the kinetic energy of the vehicle during break operation. The proposed system includes a polymer electrolyte membrane fuel cell (PEMFC) based drive train and a super capacitor connected in parallel. The system is designed and dimensioned for a conventional petrol driven propulsion system of the Mercedes B-Class160. The feasibility study also includes comparison between the existing conventional systems. It is shown that although FC power train is heavier compared to existing system, urban performance is better and produces no CO2 and other harmful emissions. 相似文献
104.
105.
Household firewood use has become increasingly popular in the United States over the past few years. Significant problems remain in estimating firewood consumption. Methods of determining the amount of wood consumed vary from state to state. Units used for measuring firewood vary, but the cord remains the researcher's favorite. Factors used for converting other units, such as pickup truck loads to cords also vary. People who do not use firewood are less likely to respond to mailed surveys, resulting in potential overestimates of statewide consumption. This paper identifies some problems associated with estimating household firewood consumption and recommends methods of dealing with them. 相似文献
106.
Dynamics of Bacterial Abundance,Biomass, Activity,and Community Composition in the Oligotrophic Traunsee and the Traun River (Austria) 总被引:1,自引:0,他引:1
Klammer Susanne Posch Thomas Sonntag Bettina Griebler Christian Mindl Birgit Psenner Roland 《Water, Air, & Soil Pollution: Focus》2002,2(4):137-163
The holomictic Traunsee is the deepest and second largest lakein Austria. The special characteristic of this ecosystem isthe fact that local salt and soda industries presumably alterthe lake by the discharge of waste materials. Since thebeginning of the 20th century salt and soda works areannually releasing up to 50,000 tons of solid wastes and up to150,000 tons of chloride into Traunsee. To assess potentialeffects of these anthropogenic impacts on the bacterioplanktonthree sampling sites, influenced as well as not influenced bythe industrial discharge, were chosen for comparison andsampled monthly from November 1997 to October 1998. Bacterialabundance ranged between 0.4 to 3.0 × 106 cells ml-1 with decreasing numbers along the depth profile. Theproportion of actively respiring bacteria, i.e. INT [2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyltetrazolium chloride]reducing cells, never exceeded 10% of DAPI (4',6'-diamidino-2-phenylindole) stained cells. Fluorescence in situ hybridization (FISH) was used to examine the seasonal and spatial distribution of dominant phylogenetic groups of thebacterioplankton. Up to 84% of bacteria detected with DAPIcould be detected via FISH applying the universal bacterialprobe EUB338. Percentages of alpha- and beta-Proteobacteriaand members of the Cytophaga-Flavobacterium cluster did notexceed 60% of DAPI-stained cells.Beta-Proteobacteriaappeared to be the most abundant group, not only in Traunsee butalso in two reference lakes, Attersee and Hallstättersee. No significant differences in any of the bacterial parameters couldbe detected between the three sampling sites and all measurementswere found in the range reported for oligotrophic lakes. The highdischarge of the Traun River, resulting in a lake water renewaltime of only one year, may diminish possible effects of industrial waste discharge in the pelagic zone. 相似文献
107.
108.
Gholam‐Abbas Barani Mohammad Javad Khanjani 《Journal of the American Water Resources Association》2002,38(4):1053-1060
ABSTRACT: To measure crop evapotranspiration, a large double tank, electronic weighting lysimeter system was designed and installed at the Shahid Bahonar University farm, Kerman, Iran. The system was installed in a 50 m2 underground building. It includes two tanks of 3.00 m in diameter and 1.75 m deep. The weighing mechanism for each tank is a set of three compression strain gage load cells, which are fixed on 1.20 m height column above the floor. According to the specification of the load cells, the maximum possible weighing error may be about 0.01 percent of total mass, which is equivalent to 0.28 mm of water, but the measured error was equal to 1 kg mass, which is equivalent to 0.14 mm of water. The load cell data from each tank and the on‐site environmental data (temperature, humidity, and wind velocity and direction) are automatically recorded and saved in a personal computer hard disk for further use and analysis. 相似文献
109.
110.