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   1918篇
  免费   181篇
  国内免费   980篇
安全科学   113篇
废物处理   119篇
环保管理   212篇
综合类   1576篇
基础理论   449篇
污染及防治   461篇
评价与监测   75篇
社会与环境   60篇
灾害及防治   14篇
  2023年   12篇
  2022年   32篇
  2021年   46篇
  2020年   43篇
  2019年   50篇
  2018年   46篇
  2017年   83篇
  2016年   83篇
  2015年   111篇
  2014年   136篇
  2013年   219篇
  2012年   172篇
  2011年   182篇
  2010年   156篇
  2009年   164篇
  2008年   125篇
  2007年   208篇
  2006年   227篇
  2005年   176篇
  2004年   137篇
  2003年   119篇
  2002年   88篇
  2001年   79篇
  2000年   73篇
  1999年   69篇
  1998年   56篇
  1997年   33篇
  1996年   22篇
  1995年   32篇
  1994年   30篇
  1993年   21篇
  1992年   14篇
  1991年   10篇
  1990年   5篇
  1988年   4篇
  1987年   1篇
  1983年   1篇
  1982年   4篇
  1980年   2篇
  1979年   1篇
  1978年   2篇
  1973年   2篇
  1971年   1篇
  1970年   1篇
  1967年   1篇
排序方式: 共有3079条查询结果,搜索用时 437 毫秒
981.
本文根据城市工业生态经济系统的构成及特点,分析了城市工业生态经济系统进行持续发展的现实意义,针对城市工业生态经济持续发展中存在的主要问题进行原因剖析,并提出了相应的治理对策及措施,以达环境与经济及城市生态经济优化决策之目的  相似文献   
982.
污水处理技术的新发展   总被引:14,自引:1,他引:14  
概述了污水处理的各种技术,总结了国外污水处理技术的最新发展动态。  相似文献   
983.
三相生物流化床处理炼油厂含酚废水的实验研究   总被引:1,自引:0,他引:1  
酚是一类剧毒性物质 ,是我国重点控制的污染物之一。本文利用三相生物流化床对人工含酚废水和燕山石化集团炼油厂含酚废水进行实验室模拟降解实验 ,生物颗粒使用海藻酸钠、氯化钙和从活性污泥筛选驯化的四种细菌用微生物包埋法制作。结果显示 ,在 3h时段内对酚的降解显著 ,t testP <0 .0 1。在三相生物流化床中使用微生物包埋法制作的生物颗粒处理含酚废水 ,处理效果良好 ,并且用海藻酸钠、氯化钙为主要原料制作生物颗粒可以大大降低处理成本。  相似文献   
984.
稠油及超稠油污水具有黏度大、油水密度差小、乳化严重、水温高、水质水量变化大、成分复杂等特点,该废水的B/C小于0.3,属于难生物降解污水.通过试验表明,采用预处理工艺先除油、除悬浮物,再进行生物处理工艺去除可生化降解COD,最后经过深度处理工艺去除残余的难生化降解COD,可保证处理后水质全面达标.  相似文献   
985.
In this research, we evaluated the toxic effect of metal ions on mycelial growth and phosphate-solubilising activity of soil-borne micromycetes isolated from the Phragmites australis rhizosphere using Pikovskaya-agar plates supplemented with four metal concentrations. The diameter growth rate (DGR) decreased as the metal concentration rise for all tested fungi. Trichoderma atroviride had the fastest growth rate (1.48?cm2?day?1) and was the least susceptible to Al3+, Cd2+, Cr3+, Cu2+ and Pb2+ with a median effective concentration (MEC50) of 12.19, 0.48, 4.51, 11.44 and 50.05?mM, respectively. Aspergillus japonicus was the most tolerant to Co2+, Ni2+ and Zn2+, with MEC50 values of 3.36, 1.095 and 2.34?mM, respectively. Penicillium italicum was the most tolerant to Cr6+ (MEC50?=?0.677?mM). The ability to solubilise phosphate remained, despite the decrease in the DGR, and P. italicum and Penicillium dipodomyicola had the highest Phosphate Solubilisation Indexes (PSIs) at 1.97 and 2.12, respectively. In particular, P. italicum recorded the highest PSI of all the studied isolates at 0.62?mM Cr3+ (PSI?=?4.74). A. japonicus and T. atroviride were the most tolerant isolates to all tested metals, which suggests that these isolates are promising candidates for further study with regard to mycoremediation and biofertilisation of metal-polluted soils.  相似文献   
986.
聚β羟基烷酸酯(PHA)是强化生物除磷系统中颗粒污泥胞内重要碳源和能源,其快速测定对强化生物除磷机理研究有重要意义. 采用Savitzky-Golay平滑法(SG)-多元散射校正法(MSC)对污泥的近红外光谱进行预处理,通过改进的偏最小二乘法(iPLS、siPLS、biPLS)建立污泥样品近红外光谱与PHA含量的定量分析模型.结果表明,SG-MSC预处理减弱噪声和背景等表面因素对光谱的影响,采用联合区间偏最小二乘法(siPLS)将全光谱等分为30个子区间, 联合子区间[13 21 24 29]建立的模型预测效果最优,其交互验证均方根误差(RMSECV)和预测均方根误差(RMSEP)分别为0.2018和0.3120,校正集和预测集相关系数分别达到0.9925和0.9391,该光谱区段与PHA分子结构中C-H的伸缩变形、弯曲振动和C=O的伸缩振动密切相关. 改进偏最小二乘有效地优化光谱建模区域,提高模型预测能力,实现污泥胞内PHA含量的快速定量分析.  相似文献   
987.
Wet air oxidation (WAO) is employed in this work for treating high concentration chemical wastewater containing phenol and/or phenolic compounds. Experimental results indicate that over 90% removal of phenol or phenolic compounds can be efficiently achieved in the WAO process. Despite of the high treatment efficiency of the WAO process, the treated wastewater, however, still retains relatively high chemical oxygen demand (COD) concentration and does not meet the safe discharge standard. Hence further treatment of the WAO treated wastewater by an aerobic biological treatment using acclimatized activated sludge is necessary. It is found in the present studies that the combined process, if appropriately operated, is capable of drastically reducing the COD concentration of the high concentration chemical wastewater to meet the safe discharge requirement. The operating conditions of the combined process are investigated to determine their respective effects on the overall treatment efficiency. The experimental data also indicate that the oxidation reaction can be represented by a first order kinetics in terms of the component or COD concentration. For both single component and multicomponent wastewaters, the WAO process was found to have different activation energy for oxidation below and above 200°C, suggesting possibly different reaction mechanisms between these temperature ranges. The experimental results provided in the present work can provide significant and practical information for optimizing the combined treatment method.  相似文献   
988.
To obtain comparable results of multi‐element analysis of plant materials by different laboratories, a harmonized sampling procedure for terrestrial and marine ecosystems is essential. The heterogeneous distribution of chemical elements in living organisms is influenced by different biological parameters. These parameters are mainly characterized by genetic predetermination, seasonal changes, edaphic and climatic conditions, and delocalization processes of chemical substances by metabolic activities.

The biological variations of the element content in plants were divided into 5 systematic levels, which are: 1. the plant species; 2. the population; 3. the stand (within an ecosystem); 4. the individual; and 5. the plant compartment. Each of these systematic levels can be related to: 1. genetic variabilities; 2. different climatic, edaphic and anthropogenic influences; 3. microclimatic or microedaphic conditions; 4. age of plants (stage of development), exposure to environmental influences (light, wind, pollution etc.), seasonal changes; and 5. transport and deposition of substances within the different plant compartments (organs, tissues, cells, organelles).

An expert system for random and systematic sampling for multi‐element analysis of environmental materials, such as plants, soils and precipitation is presented. After statistical division of the research area, the program provides advice for contamination‐free collection of environmental samples.  相似文献   
989.
Book Reviews     
The study focused on the so-called dark coniferous forest belt on the northern slope of Changbai Mountain, at an altitude of 1100 to 1700 m. Forty tree species, 50 shrub species and 165 herb species were recorded in a series of transects. The main impact factors on forest diversity and proposals for sustainable management of this diversity were studied using an altitude and area gradient pattern method. The results showed that the diversity of dark coniferous forest gradually decreased from lower to upper altitude; while the importance value of key species increased. The methodology used to assess attributes for conservation of dark coniferous forest diversity involved measurement of individual trees, number of species, age structure, stand structure, diameter at breast height (DBH), and cumulative wood storage. Different conservation strategies have been developed and are discussed for different parts of the forest.  相似文献   
990.
在4个序批式反应器(SBR)R1、R2、R3和R4中,以静置段代替传统厌氧段,采用后置缺氧,考察进水氨氮浓度分别为20,30,40,50mg/L对静置/好氧/缺氧SBR脱氮除磷性能的影响.结果表明,R1、R2、R3和R4长期运行中磷去除率分别为82.3%、92.8%、92.6%和89.1%,总氮(TN)去除率分别为97.2%、88.6%、84.5%和72.6%.静置段省却搅拌,但仍起厌氧段作用,仍可实现生物强化除磷.4个反应器好氧段均发生同步硝化-反硝化(SND),分别贡献14.7%、16.6%、17.8%和14.8%的进水后TN量,且后置缺氧段利用糖原驱动反硝化,脱氮效果较好,出水TN分别为0.57,4.43,6.61,13.70mg/L.研究表明,进水氨氮浓度可影响静置释磷、好氧摄磷、反硝化除磷.静置段代替厌氧段的后置缺氧工艺可取得较好脱氮除磷效果,且节约成本,简化工艺.  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