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   255篇
  免费   1篇
安全科学   7篇
废物处理   16篇
环保管理   28篇
综合类   61篇
基础理论   36篇
污染及防治   70篇
评价与监测   24篇
社会与环境   12篇
灾害及防治   2篇
  2023年   3篇
  2022年   6篇
  2021年   5篇
  2020年   4篇
  2019年   5篇
  2018年   8篇
  2017年   13篇
  2016年   15篇
  2015年   12篇
  2014年   17篇
  2013年   21篇
  2012年   21篇
  2011年   17篇
  2010年   7篇
  2009年   13篇
  2008年   8篇
  2007年   10篇
  2006年   10篇
  2005年   10篇
  2004年   13篇
  2003年   6篇
  2002年   6篇
  2001年   1篇
  2000年   1篇
  1997年   3篇
  1995年   2篇
  1994年   2篇
  1993年   2篇
  1992年   2篇
  1991年   2篇
  1990年   3篇
  1989年   1篇
  1986年   1篇
  1984年   1篇
  1961年   1篇
  1958年   1篇
  1943年   1篇
  1941年   1篇
  1938年   1篇
排序方式: 共有256条查询结果,搜索用时 31 毫秒
161.
In Italy quarrying causes relevant environmental damages and alterations to the land and the ecosystems. Despite the present Italian legislation requiring the restoration of the sites after exploitation, most of the quarries, both the abandoned and the still operational ones, are not restored.The objective of this work is to indicate a monitoring methodology in order to survey the present state of the quarry sites and their evolution in time, which are the basic data needed to implement an adequate land reclamation project.Such methodology has been applied to several abandoned limestone quarries in the Latina province (close to Rome), characterised by a typical Mediterranean vegetation, but it can be applied to any other kind of litology and vegetation.The land monitoring has been realised both by using remote sensing techniques, supported by a Geographic Information System of the studied area, and by in situ surveying. The in situ surveying was able to assess the capability of the remote sensing model to describe the state of each site.  相似文献   
162.
The aim of this paper is to propose an alternative approach for outlining policy responses to stimulate the automotive industry. The scientific community has developed and employed the Delphi method to collect and convey perspectives and impressions, and also define a number of financially viable proposals. The panel of experts takes the view that traditional industrial policy measures denote limited effects to stimulate car demand, in a context of a macro-economic downturn. By contrast, the panel also believe incentives for car demand are important for environmental purposes, for safety and for the diversification of energy sources. The policy measures proposed are fundamental from the viewpoint of overturning path dependencies in the automotive industry which impede the diffusion of alternative vehicles, with respect to business models and consumer attitudes.  相似文献   
163.
164.
A holistic assessment procedure has been used in this study for comparing conventional activated sludge (CAS) and membrane bioreactor (MBR) processes for the treatment of municipal wastewater. Technical, social, administrative, economic and environmental impacts have been evaluated based on 1 year of operational data from three full-scale lines (one MBR and two CAS) working in parallel in a large municipal treatment plant. The comparative assessment evidences a slight advantage of the conventional process in the studied case, essentially due to lower costs, complexity and energy consumption. On the other hand, the MBR technology has a better social acceptance and similar overall environmental footprint. Although these results are influenced by site-specific parameters and cannot be generalized, the assessment procedure allowed identifying the most important factors affecting the final scores for each technology and the main differences between the compared technologies. Local conditions can affect the relative importance of the assessed impacts, and the use of weighting factors is proposed for better tailoring the comparative assessment to the local needs and circumstances. A sensitivity analysis on the weighted final scores demonstrated how local factors are very important and must be carefully evaluated in the decision making process.  相似文献   
165.
The main aim of this systematic review was to explore the outcome of fetuses with isolated echogenic bowel (EB) on antenatal ultrasound. Inclusion criteria were singleton pregnancies with isolated EB no associated major structural anomalies at the time of diagnosis. The outcomes observed were: chromosomal anomalies, cystic fibrosis (CF), associated structural anomalies detected only at follow-up scans and at birth, regression during pregnancy, congenital infections, intra-uterine (IUD), neonatal (NND) and perinatal (PND) death. Twenty-five studies (12 971 fetuses) were included. Chromosomal anomalies occurred in 3.3% of the fetuses, mainly Trisomy 21 and aneuploidies involving the sex chromosomes. Cystic fibrosis occurred in 2.2%. Congenital infections affected 2.2%, mainly congenital Cytomegalovirus (CMV) infection. The majority of fetuses with EB experienced regression or disappearance of the EB at follow-up scans. Associated anomalies were detected at a follow-up scan in 1.8%. Associated anomalies were detected at birth and missed at ultrasound in 2.1% of cases. IUD occurred in 3.2% of cases while the corresponding figures for NND and PND were 0.4% and 3.1%. Fetuses with EB are at increased risk of adverse perinatal outcome, highlighting the need for a thorough antenatal management and postnatal follow-up. Assessment during pregnancy and after birth should be performed in order to look for signs of fetal aneuploidy, congenital infections and associated structural anomalies.  相似文献   
166.
167.
Ventricular aneurysms have rarely been reported prenatally. Their prognosis is variable depending on factors such as early detection, their relative size in comparison to the ventricular cavity, growth on follow-up, and signs of cardiac failure. In view of the fact that it may be useful to report on additional cases in order to make available further information on aetiology, prognosis and neonatal management, we hereby report on two cases of ventricular aneurysm with good mid-term prognosis. One case of apical aneurysm of the left ventricle was associated with a muscular ventricular septal defect, the features of which are compatible with a fetal myocardial infarction and ventricular septal rupture in absence of coronary artery anomalies as demonstrated by catheterisation. Another case of sub-tricuspidal aneurysm of the right ventricle associated with mitral prolapse appears to be a component of diffuse connective dysplasia. Despite the early gestational age at diagnosis, the large size of the aneurysm and the associated defect, both the infants were asymptomatic in infancy prompting a conservative management. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
168.
Attempting to assess the risk of a release from a potentially polluting marine site (PPMS) can be a very subjective process. The Marine Site Risk Index (MaSiRI) is designed to provide a more objective approach to this process by adopting a table-based evaluation scheme, while still allowing for the inevitable unknown conditions by including a subjective ‘expert correction’ in a suitably controlled manner. Building on a geographic database of PPMS records, the MaSiRI algorithm applies data filters to remove PPMS records for which it is not applicable and then estimates a basic risk index based on core data that almost all sites would contain. It can then refine the results for those sites that have auxiliary data, varying the assessed risk as appropriate, according to standard rule-sets. A risk level of confidence is computed and adjusted to express dynamic confidence in the risk value (e.g., due to reliance on estimates rather than measured values), and where appropriate an upper and lower bound of risk can be used to assess the range of values associated with an estimated parameter. This information can be visualized by a composite quality symbol proposed here. MaSiRI is demonstrated on three illustrative shipwrecks and then compared against the DEvelopment of European guidelines for Potentially Polluting (DEEPP) project database from the Pelagos Sanctuary in the western Mediterranean. The aggregate results of the comparison are broadly similar to DEEPP, within the limits of the comparison, but provide a more detailed analysis in the case of estimated pollutant volume and ubiquitous assessment of levels of confidence.  相似文献   
169.
BACKGROUND: Chlorophenols (CPs) constitute a group of organic pollutants that are introduced into the environment as a result of several man-made activities, such as uncontrolled use of pesticides and herbicides, and as byproducts in the paper pulp bleaching. Promising removal technologies of chlorinated aromatics consist in the application of advanced oxidation processes (AOPs) that can provide an almost total degradation of a variety of contaminants. Among these, wide application find Fenton systems based on generation of reactive species having a high oxidizing power, such as hydroxyl radical HO*. Our objective was that of determining the overall degradation efficiency of the model compound 2,4-dichlorophenol (DCP) by thermal Fenton-type oxidation systems with a view toward defining in more details relevant process parameters, the effect of reaction temperature and of co-catalyst Cu2+. METHODS: Reaction conditions were similar to those generally adopted as optimal in many practical applications, i.e. pollutant/Fe2+ (as FeSO4) ratio ca. 20, Fe2+/Cu2+ (co-catalyst) 2:1, pH adjusted and controlled at pH 3, and H2O2 in excess (up to four-fold over the stoichiometric amount required for complete mineralization). RESULTS AND DISCUSSION: The results demonstrate that it is advantageous to carry out the reaction at a temperature markedly higher (70 degrees C) than ambient. The stepwise addition of H2O2 in aliquots yields an efficient transformation, while allowing a convenient control of the reaction exothermicity. Under these conditions, the essentially complete removal of the initial DCP is accomplished using just one equiv of H2O2 during 15 min; excess H2O2 (5 equivalents) yields extensive substrate mineralization. Also relevant, at 70 degrees C dechlorination of the initial DCP (and of derived reaction intermediates) is remarkably extensive (3-5% residual TOX), already with the addition of 1 equiv of H2O2. At the end of the reaction, IC and IC-MS analyses of the solution reveal that only low-molecular weight carboxylic acid (acetic, formic, oxalic, malonic, tartaric, etc.) contribute to the residual TOC. CONCLUSIONS: The whole of the results herein point to the advantage of performing the process at temperatures substantially higher than ambient (70 degrees C). Under the conditions adopted, almost complete degradation of the initial toxic compound can be achieved using hydrogen peroxide in fair excess (e.g., 3.5 equiv H2O2). RECOMMENDATIONS AND OUTLOOK: In applying practical Fenton-type degradation systems to heavily polluted wastes, either for the pre-treatment of waters with a high COD value prior to biodegradation or for complete mineralization of pollutants, the set up of appropriate reaction conditions appears to be a key factor. Also, it is desirable to keep the concentration of iron salts within the lower limits in order to minimize the production and disposal of iron oxide sludges.  相似文献   
170.
A study was done to evaluate the effects of diagnostic ultrasound on sister chromatid exchange (SCE) in first-trimester chorionic villi under controlled technical conditions. Chromosome analysis was performed by the direct method using spontaneous mitoses from the cytotrophoblast layer, and SCE visualization was accomplished by a 72 h treatment with 5-bromodeoxyuridine (BrdU) at a concentration of 10μg/ml. The slides were stained with ac ridine orange. Immediately before first-trimester chorionic villus sampling, a group of ten pregnant women was exposed to diagnostic ultrasound for 20min (in vivo exposure). This group of patients was compared with a control group who were not exposed. A mean value of SCE/cell frequency of 4·2 ± 0·2 was found in the exposed pregnancies, while a value of 3·7 ± 0·2 was observed in the control group. After in vitro exposure of chorionic villi obtained from elective abortions, the frequency of SCE/cell did not differ significantly among samples with different exposures (1,2, and 3 h) and controls. The positive control (mitomycin C) yielded a significant increase in SCE frequency.  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