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   421篇
  免费   26篇
  国内免费   131篇
安全科学   45篇
废物处理   28篇
环保管理   26篇
综合类   213篇
基础理论   67篇
污染及防治   127篇
评价与监测   34篇
社会与环境   19篇
灾害及防治   19篇
  2024年   2篇
  2023年   9篇
  2022年   24篇
  2021年   22篇
  2020年   16篇
  2019年   17篇
  2018年   26篇
  2017年   27篇
  2016年   27篇
  2015年   20篇
  2014年   19篇
  2013年   57篇
  2012年   49篇
  2011年   44篇
  2010年   19篇
  2009年   25篇
  2008年   26篇
  2007年   26篇
  2006年   26篇
  2005年   23篇
  2004年   11篇
  2003年   15篇
  2002年   10篇
  2001年   3篇
  2000年   5篇
  1999年   10篇
  1998年   7篇
  1996年   2篇
  1995年   3篇
  1994年   2篇
  1993年   2篇
  1992年   1篇
  1990年   1篇
  1976年   1篇
  1930年   1篇
排序方式: 共有578条查询结果,搜索用时 132 毫秒
121.
The collapse of the World Trade Center (WTC) on September 11, 2001, generated large amounts of dust and smoke that settled in the surrounding indoor and outdoor environments in southern Manhattan. Sixteen dust samples were collected from undisturbed locations inside two uncleaned buildings that were adjacent to Ground Zero. These samples were analyzed for morphology, metals, and organic compounds, and the results were compared with the previously reported outdoor WTC dust/smoke results. We also analyzed seven additional dust samples provided by residents in the local neighborhoods. The morphologic analyses showed that the indoor WTC dust/smoke samples were similar to the outdoor WTC dust/smoke samples in composition and characteristics but with more than 50% mass in the <53-microm size fraction. This was in contrast to the outdoor samples that contained >50% of mass above >53 microm. Elemental analyses also showed the similarities, but at lower concentrations. Organic compounds present in the outdoor samples were also detected in the indoor samples. Conversely, the resident-provided convenience dust samples were different from either the WTC indoor or outdoor samples in composition and pH, indicating that they were not WTC-affected locations. In summary, the indoor dust/smoke was similar in concentration to the outdoor dust/smoke but had a greater percentage of mass <53 microm in diameter.  相似文献   
122.
在空气气氛下,对医疗废物中几种有代表性的有机质进行非等温热解实验。分析实验结果发现,热解失重曲线与N2气氛下不同,出现多个DTG峰。利用Freeman—CarroⅡ法求出了各有机质的表观动力学参数,并建立了能较好反映各物料失重过程的表观多步反应动力学模型。针对混合物料无法直接求出表观动力学参数,建立了多组分反应动力学模型。  相似文献   
123.
Profiles of PAH emission from steel and iron industries   总被引:5,自引:0,他引:5  
Yang HH  Lai SO  Hsieh LT  Hsueh HJ  Chi TW 《Chemosphere》2002,48(10):3777-1074
In order to characterize the polycyclic aromatic hydrocarbons (PAHs) emission from steel and iron industries, this study measured the stack emission of twelve steel and iron plants in southern Taiwan to construct a set of source fingerprints. The study sampled the emissions by the USEPA's sampling method 5 with the modification of Graseby for the gas and particulate phase PAH and, then, used Hewlett-Packard 5890 gas chromatograph equipped with mass spectrometer detector to analyze the samples. The steel and iron industries are classified into three categories on the basis of auxiliary energy source: Category I uses coal as fuel, Category II uses heavy oil as fuel and Category III uses electric arc furnace. The pollution source profiles are obtained by averaging the ratios of individual PAH concentrations to the total concentration of 21 PAHs and total particulate matter measured in this study. Results of the study show that low molecular weight PAHs are predominant in gas plus particulate phase for all three categories. For particulate phase PAHs, however, the contribution of large molecular weight compounds increases. Two-ring PAHs account for the majority of the mass, varying from 84% to 92% with an average of 89%. The mass fractions of 3-, 4-, 5-, 6-ring PAHs in Category I are found to be more than those of the other two categories. The mass of Category III is dominated by 7-ring PAHs. Large (or heavy) molecular weight PAHs (HMW PAHs) are carcinogenic. Over all categories, these compounds are less than 1% of the total-PAH mass on the average. The indicatory PAHs are benz[a]anthracene, benzo[k]fluoranthene, benzo[ghi]perylene for Category I, benzo[a]pyrene, acenaphthene, acenaphthylene for Category II and coronene, pyrene, benzo[b]chrycene for Category III. The indicatory PAHs among categories are very different. Thus, dividing steel and iron industry into categories by auxiliary fuel is to increase the precision of estimation by a receptor model. Average total-PAH emission factors for coal, heavy oil and electric arc furnace were 4050 μg/kg-coal, 5750 μg/l-oil, 2620 μg/kW h, respectively. Carcinogenic benzo[a]pyrene for gas plus particulate phase was 2.0 g/kg-coal, 2.4 μg/l-oil and 1.4 μg/kW h for Category I, II and III, respectively.  相似文献   
124.
J. Badia  T. Do Chi 《Marine Biology》1976,36(2):159-168
The structure and evolution of populations of Squilla mantis (Crustacea: Stomatopoda) have been studied, and the statistical techniques used are discussed. Population studies were performed by multivariate analysis. Thirty-three monthly samples comprising 20 length classes of males and females were examined. Males and females display evolutionary cycles: each cycle begins in June/July and proceeds through a succession of evolution and eventual regression, the later being particularly marked every 2 years.  相似文献   
125.
本文报道了以黄铁矿和还原铁粉或其代用品为原料,制备含砷废水净化剂-硫化亚铁的方法。原料配比为100:35,粒度≤100目,反应温度为200~350℃是制备的最佳条件。本法原料广,工艺简单,成本低,具有良好的开发应用前景。  相似文献   
126.
大学校园的生态足迹探究   总被引:1,自引:0,他引:1  
生态足迹分析法是评价绿色校园建设水平较好的指标之一,能定量揭示学校的生态状况,本文结合黑龙江科技学院的校园状况,简要介绍生态足迹成分法的原理和计算分析方法.研究结果表明,黑龙江科技学院2005年总生态足迹为18410.53 hm2,即需要18410.53 hm2生态生产性土地来支持学校的各类消费以及吸纳废弃物;人均生态足迹为0.94 hm2/人,与全国人均生态足迹1.5 hm2相比较,学校的生态状况比较乐观.  相似文献   
127.
The sol–gel method was used to synthesize a series of metal oxides-supported activated carbon fiber (ACF) and the simultaneous catalytic hydrolysis activity of carbonyl sulfide (COS) and carbon disulfide (CS2) at relatively low temperatures of 60°C was tested. The effects of preparation conditions on the catalyst properties were investigated, including the kinds and amount of metal oxides and calcination temperatures. The activity tests indicated that catalysts with 5 wt.% Ni after calcining at 400°C (Ni(5)/ACF(400)) had the best performance for the simultaneous catalytic hydrolysis of COS and CS2. The surface and structure properties of prepared ACF were characterized by scanning electron microscope-energy disperse spectroscopy (SEM-EDS), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), carbon dioxide-temperature programmed desorption (CO2-TPD) and diffuse reflectance Fourier transform infrared reflection (DRFTIR). And the metal cation defects were researched by electron paramagnetic resonance (EPR) method. The characterization results showed that the supporting of Ni on the ACF made the ACF catalyst show alkaline and increased the specific surface area and the number of micropores, then improved catalytic hydrolysis activity. The DRFTIR results revealed that -OH species could facilitate the hydrolysis of COS and CS2; -COO and -C–O species could facilitate the oxidation of catalytic hydrolysate H2S. And the EPR results showed that high calcination temperature conditions provide more active reaction center for the COS and CS2 adsorption.  相似文献   
128.
随着社会的进步,传统环境监控日渐式微,存在效率低问题。针对这个问题,基于Web环境监控查询系统成为近几年研究的焦点。综合国内外相关研究资料,设计一个基于Web的环境监控数据查询系统。该系统实现了通过网络共享远程终端数据对环境的实时监控,推动环保工作的现代化管理。为验证其有效性,系统在设计完成后在某地进行了为期6个月的投入实验。基于Web的环境监控数据查询系统较传统监控系统效率更高,满足了人们的需求,对未来相似系统设计有一定的借鉴意义。  相似文献   
129.
Nanoscale zero-valent iron(nZVI) assembled on graphene oxide(GO)(rGO-nZVI) composites were synthesized by reduction of GO and ferrous ions with potassium borohydride,for use in Cr(VI) removal from aqueous solution.The results showed that the two-dimensional structure of GO could provide a skeleton support for Fe~0,thus overcoming the bottleneck of aggregation for nZVI.Also,rGO-nZVI would form a ferric-carbon micro-electrolysis system in Cr(VI)-contaminated aquifers,enhancing and accelerating electron transfer,exhibiting high rate and capacity for Cr(VI) removal.The optimum dosage of the applied r GO-nZVI was linearly correlated with the initial Cr(VI) concentration.Characterization of rGO-nZVI before and after reaction with Cr(VI) revealed the process of Cr(VI) removal:r GO-nZVI firstly transferred electrons from Fe~0 cores via their Fe(II)/Fe(III) shells to the GO sheet;there,negatively charged Cr(VI) received electrons and changed into positively charged Cr(III),which was adsorbed by the negatively charged GO sheet,avoiding the capping and passivating of nZVI.rGO-nZVI formed a good electrically conductive network,and thus had long-term electron releasing properties,which was important for groundwater remediation.  相似文献   
130.
This paper reports on a study which explored the possible relationship between road traffic noisescape and urban form in Hong Kong. A total of 212 residential complexes from 11 contrasting urban forms were sampled, and their noise levels assessed both at dwelling and neighbourhood scales by noise mapping. Its findings indicate that residential complexes with different urban forms have significantly different noisescape attributes. There is a strong correlation between the noise characteristics and morphological indicators at the dwelling scale. A less obstreperous noisescape is associated with urban forms with lower road and building densities, and with building arrangements which provide self-noise screening. These findings suggest that urban form is an influential determinant of the noisescape in the urban environment, and they point to the need to rethink the conventional approach to managing the urban acoustic environment.  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