全文获取类型
收费全文 | 696篇 |
免费 | 45篇 |
国内免费 | 20篇 |
专业分类
安全科学 | 241篇 |
废物处理 | 6篇 |
环保管理 | 88篇 |
综合类 | 202篇 |
基础理论 | 48篇 |
污染及防治 | 14篇 |
评价与监测 | 31篇 |
社会与环境 | 33篇 |
灾害及防治 | 98篇 |
出版年
2023年 | 5篇 |
2022年 | 19篇 |
2021年 | 18篇 |
2020年 | 22篇 |
2019年 | 18篇 |
2018年 | 13篇 |
2017年 | 25篇 |
2016年 | 20篇 |
2015年 | 27篇 |
2014年 | 28篇 |
2013年 | 37篇 |
2012年 | 60篇 |
2011年 | 48篇 |
2010年 | 42篇 |
2009年 | 45篇 |
2008年 | 38篇 |
2007年 | 38篇 |
2006年 | 56篇 |
2005年 | 28篇 |
2004年 | 30篇 |
2003年 | 29篇 |
2002年 | 29篇 |
2001年 | 27篇 |
2000年 | 14篇 |
1999年 | 14篇 |
1998年 | 5篇 |
1997年 | 7篇 |
1996年 | 2篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1986年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有761条查询结果,搜索用时 234 毫秒
671.
A nation-wide ecosystem science network for Canada was formed in 1994. At that time, mercury was a re-emerging issue in Canada and the Coordinating Office for the networksought collaboration to assess the issue. The key mechanismsby which the network has added value in addressing this issue are: 1) Information Dissemination, the network has organised, facilitated and co-hosted a number of regional,national and international mercury events (meetings, conferences and workshops) which have served to bring theexpertise together, the network also disseminates informationon it's web page, and the Coordinating Office hosts an annualNational Science Conference; 2) Collaborative Mercury Monitoring, network partners advocated the need for a singlehemispheric mercury network which resulted in the developmentof a compatible Canada–U.S. mercury deposition network, whichmay also be expanded into Mexico, and 3) Environmental Reporting, the network has collaborated with others to reporton current mercury findings through initiatives such as the 1998 Northeast States and Eastern Canadian Mercury Study, a 1999 Mercury Case Study and is presently a partner in the University of Quebec's proposal to form a Collaborative Mercury Ecosystem Research Network in Canada. 相似文献
672.
A. T. Hodgson D. Faulkner D. P. Sullivan D. L. DiBartolomeo M. L. Russell W. J. Fisk 《Atmospheric environment (Oxford, England : 1994)》2003,37(39-40):5517
A study of the relationship between outside air ventilation rate and concentrations of volatile organic compounds (VOCs) generated indoors was conducted in a call center office building. The building, with two floors and a total floor area of 4600 m2, is located in the San Francisco Bay Area, CA. Ventilation rates were manipulated with the building's four air handling units (AHUs). VOC and CO2 concentrations in the AHU returns were measured on 7 days during a 13-week period. VOC emission factors were determined for individual zones on days when they were operating at near steady-state conditions. The emission factor data were subjected to principal component (PC) analysis to identify groups of co-varying compounds. Potential sources of the PC vectors were ascribed based on information from the literature. The per occupant CO2 generation rates were 0.0068–0.0092 l s−1. The per occupant isoprene generation rates of 0.2–0.3 mg h−1 were consistent with the value predicted by mass balance from breath concentration and exhalation rate. The relationships between indoor minus outdoor VOC concentrations and ventilation rate were qualitatively examined for eight VOCs. Of these, acetaldehyde and hexanal, which likely were associated with material sources, and decamethylcyclopentasiloxane, associated with personal care products, exhibited general trends of higher concentrations at lower ventilation rates. For other compounds, a clear inverse relationship between VOC concentrations and ventilation was not observed. The net concentration of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate isomers, examples of low-volatility compounds, changed very little with ventilation likely due to sorption and re-emission effects. These results illustrate that the efficacy of ventilation for controlling VOC concentrations can vary considerably depending upon the operation of the building, the pollutant sources and the physical and chemical processes affecting the pollutants. Thus, source control measures, in addition to adequate ventilation, are required to limit concentrations of VOCs in office buildings. 相似文献
673.
674.
Measurements of carbonyls in a 13-story building 总被引:1,自引:0,他引:1
Báez AP Padilla HG García RM Belmont RD Torres Mdel C 《Environmental science and pollution research international》2004,11(6):400-404
BACKGROUND, AIM AND SCOPE: Formaldehyde and acetaldehyde are emitted by many mobile and stationary sources and secondary aldehydes are intermediates in the photo-oxidation of organic compounds in the atmosphere. These aldehydes are emitted indoors by many materials such as furniture, carpets, heating and cooling systems, an by smoking. Carbonyls, mainly formaldehyde and acetaldehyde, have been studied because of their adverse health effects. In addition, formaldehyde is a suspected carcinogen. Therefore, the concentrations of formaldehyde and acetaldehyde were determined to assess the inhalation exposure doses to carbonyls for people who work in a 13-story building and in order to evaluate the cancer hazard. METHODS: Carbonyl compounds in indoor and outdoor air were measured at a 13-story building located in Mexico City. The mezzanine, fifth and tenth floors, and the third level-parking garage were selected for sampling. Samples were collected in two sampling periods, the first from April 20 to 29, 1998 and the second from December 1 to 20, 1998. Carbonyls were sampled by means of DNHP-coated cartridges at a flow rate of 1 l min(-1) from 9:00 to 19:00 hours, during 2-hour time intervals and analyzed by HPLC with hours, during 2-hour time intervals and analyzed by HPLC with UV/VIS detection. RESULTS: Mean carbonyl concentrations were highest in the 3rd level-parking garage, with the formaldehyde concentration being the highest ranging from 108 to 418 microg m(-3). In working areas, the highest carbonyl arithmetic mean concentrations (AM) were observed on the 5th floor. Acetone and formaldehyde concentrations were highest in April ranging from 161 to 348 microg m(-3) (AM = 226) and from 157 to 270 microg m(-3) (AM = 221), respectively. Propionaldehyde and butyraldehyde were present in smaller concentrations ranging from 2 to 25 and 1 to 28 microg m(-3), respectively, considering all the samples. Mean indoor/outdoor ratios of carbonyls ranged from 1.8 to 9.6. A reduction of inhalation exposure doses of 41% and 45% was observed in the fifth floor air after the air conditioning systems had been repaired. Formaldehyde and acetaldehyde concentrations were higher in smoking environments. CONCLUSION: Indoor carbonyl concentrations were significantly greater than outdoor concentrations. Tobacco smoke seems to be the main indoor source of formaldehyde. After the air conditioning system was maintained and repaired (as was recommended), an important reduction in the emission of formaldehyde and acetaldehyde was achieved on all floors, except for the 3rd level parking garage, thereby reducing the inhalation exposure doses. RECOMMENDATION: The results obtained in this research demonstrated that maintenance of air conditioning systems must be carried out regularly in order to avoid possible adverse effects on health. Additionally, it is mandatory that isolated smoking areas, with air extraction systems, be installed in every public building. 相似文献
675.
676.
浅谈建筑材料利用与环境保护 总被引:2,自引:0,他引:2
建筑材料在取材、生产加工、运输、使用和废弃的过程中,排放出大量废水、废气和废渣,对人类的健康造成威胁,产生有害物质,导致大气、水体和土壤污染.因此要开发与生产资源节约型和环保型建筑材料,制定健全的建材环保法规来保护环境. 相似文献
677.
根据钢结构建筑构件耐火性能的特点,应用建筑防火安全性能化设计系统方法对钢结构建筑发生火灾时热、烟对建筑结构和建筑内人员的影响进行了分析研究,确定了火灾下人员与建筑结构的安全准则。运用FDS4.0对一建筑实例建模,通过模型与建筑实际火灾相似性的计算机数值模拟研究,得出了火灾情况下建筑内的热、烟蔓延情况,同时采用ANSYS8.0分析技术对火灾下钢结构的结构反应进行了研究。以性能化设计系统方法对钢结构建筑发生火灾进行了耐火分析研究,在此基础上给出了定量的分析方法,为钢结构建筑的火灾安全工程设计和应用提供了一种新的技术。 相似文献
678.
张泽江 《中国安全生产科学技术》2006,2(1):28-30
本文从火灾保险发展历程出发,阐述了进行火灾风险评估的必要性。概述了火灾风险评估的概念的内涵,介绍了国内外较新的火灾风险评估方法,然后对火灾风险评估现状进行了总结;重点叙述了火灾损失评估技术发展情况,并提出了当前急需开展火灾机理和预防措施研究,火灾损失率的数学期望和方差的确定等研究的方向。 相似文献
679.
680.