全文获取类型
收费全文 | 545篇 |
免费 | 71篇 |
国内免费 | 128篇 |
专业分类
安全科学 | 125篇 |
废物处理 | 29篇 |
环保管理 | 67篇 |
综合类 | 346篇 |
基础理论 | 39篇 |
污染及防治 | 73篇 |
评价与监测 | 32篇 |
社会与环境 | 17篇 |
灾害及防治 | 16篇 |
出版年
2024年 | 5篇 |
2023年 | 13篇 |
2022年 | 27篇 |
2021年 | 30篇 |
2020年 | 15篇 |
2019年 | 18篇 |
2018年 | 17篇 |
2017年 | 18篇 |
2016年 | 26篇 |
2015年 | 28篇 |
2014年 | 35篇 |
2013年 | 61篇 |
2012年 | 71篇 |
2011年 | 50篇 |
2010年 | 29篇 |
2009年 | 29篇 |
2008年 | 33篇 |
2007年 | 34篇 |
2006年 | 32篇 |
2005年 | 21篇 |
2004年 | 24篇 |
2003年 | 25篇 |
2002年 | 16篇 |
2001年 | 24篇 |
2000年 | 8篇 |
1999年 | 8篇 |
1998年 | 10篇 |
1997年 | 14篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1982年 | 2篇 |
1979年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有744条查询结果,搜索用时 15 毫秒
621.
622.
The thermal explosion problem of cumene hydroperoxide exothermic reaction which is used in chemical industries for production of some chemical materials is investigated. The analytical solutions of the problem to determine the margin between ignition and non-ignition systems are presented. The solution offers different analytical expressions which relate between the critical parameters for both steady and unsteady-states in different planes of solutions for different cases. The numerical solutions in different planes offer different trajectories of solution as sub-critical (non-ignition) and supercritical (ignition). Also from the numerical solution the relations between the critical parameters are presented. The critical behaviors from both analytical and numerical solutions are concise and pertained the same results. 相似文献
623.
624.
A specific problem encountered in ecosystem-level simulation of Arctic ecosystems is the depth and extent of the driving variable record. Often, climate records are of short duration, gathered at locations different from the area to be simulated, or do not contain all the variables required by a given model. This paper addresses this problem for ecosystem simulation in Alaska with the development of a weather generator. The generator, called WGENAL, is based on the WGEN climate generator developed and validated in the 48 conterminous states. Because of the extreme variability of weather in Alaska that is not accommodated by the statistical metrics in the earlier model, a new climate generator was developed. WGENAL generates daily values of precipitation, maximum temperature, minimum temperature, solar radiation, and wind run. Precipitation is generated using a Markov chain-gamma model. A two-parameter gamma distribution is used to generate wind run. Temperatures and solar radiation are generated using procedures developed in the earlier study. Validation of the generator shows it provides adequate diurnal and seasonal weather records for Fairbanks. Other comparisons of synthetic weather with observed weather for sites north of the Brooks Range in Alaska are also within the error of the original data. 相似文献
625.
Kensuke Ushijima Shinya Kanno Itoko Kanno Mitsuhiro Ohnishi 《Journal of environmental science and health. Part. B》2016,51(3):170-175
Scallop hepatopancreas, fishery waste, contains relatively high levels of Cd and organic nitrogen compounds, the latter of which represent a fertilizer. In this study, raw scallop hepatopancreas tissue was thermally treated with sawdust and red loam in the presence of an iron catalyst to produce compost-like materials (CLMs). Two CLM samples were prepared by varying the content of raw scallop hepatopancreas tissue: 46 wt.% for CLM-1 and 18 wt.% for CLM-2. Mixtures of control soil (CTL) and CLMs (CLM content: 10 and 25 wt.%) were examined for the growth of alfalfa (Medicago sativa L.) to evaluate the risks and benefits of using this material for fertilization. The Cd content in shoots and roots of alfalfa, that were grown in the presence of CLMs, was significantly higher than those for the plants grown in the CTL, indicating that Cd had accumulated in the plants from CLMs. The accumulation of Cd in the alfalfa roots was quite high in the case of the 25% CLM-1 sample. However, alfalfa growth was significantly promoted in the presence of 10% CLM-1. This can be attributed to the higher levels of nitrogen and humic substances, which serve as fertilizer components. Although the fertilization effect in case of CLM-1showed a potential benefit, the accumulation of Cd in alfalfa was clearly increased in the presence of both CLMs. In conclusion, the use of CLMs produced from raw scallop hepatopancreas tissue can be considered to have a desirable benefit from standpoint of its use as fertilizer, but is accompanied by a risk of the accumulation of Cd in alfalfa plants. 相似文献
626.
In this study, a methodology for the assessment of fireproofing materials performance is presented. The methodology is based on a combined experimental and numerical approach. A modified version of the ASTM E162 standard fire test was used to expose specimens of steel board protected with different types of fireproofing materials to a steady radiation source. The temperature of the steel board was recorded with an infrared camera in order to evaluate the heat up due to the fire and characterize the protective performance. Experimental results were used to validate a simplified mono-dimensional model which allowed simulating more severe conditions and different protection configurations. A specific key performance indicator (KPI) was used for the quantitative assessment of fireproofing effectiveness. Finally, the professional career of Menso Molag, safety pioneer in the framework of hazardous materials transportation, was outlined. 相似文献
627.
高梯度磁分离技术在水处理中的应用及发展 总被引:1,自引:0,他引:1
高梯度磁分离技术是一种新型的水处理技术,目前已经得到了大量应用,具有广阔的应用前景。本文介绍了它的基本原理,综述了该技术在水处理中的应用现状,并做出了展望。 相似文献
628.
《Journal of Loss Prevention in the Process Industries》2011,24(6):805-813
First principles and molecular dynamics methods where used to study energetic materials (EM) of varying sensitivity, particularly nitromethane (NM) and pentaerythritol tetranitrate (PETN). Molecular and electronic structure, as well as anisotropic elastic properties, variation of charge distributions, and stress-strain behavior of these three materials were investigated. Information obtained from different levels of theory is useful to reveal and assess the anisotropic sensitivity of the studied systems. For NM, we observe a crystallographic phase transformation and a drastic change in its mechanical behavior. PETN is observed to be mechanically stable within the studied pressure range, with a marked anisotropic behavior when compressed at elevated temperatures. 相似文献
629.
A. Bernatik P. SenovskyM. Pitt 《Journal of Loss Prevention in the Process Industries》2011,24(1):19-24
The aim of this article is to summarize the safety and security aspects of storing of Liquefied Natural Gas (LNG) as a potential alternative fuel. The contribution deals with possible scenarios of accidents associated with LNG storage facilities and with a methodology for the assessment of vulnerability of such facilities. The protection of LNG storage facilities as element of critical infrastructure should also be a matter of interest to the state. The study presents the results of determination of hazardous zones around LNG facilities in the event of various sorts of release. For calculations, the programs ALOHA, EFFECTS and TerEx were used and results obtained were compared. Scenarios modelled within this study represent a possible approach to the preliminary assessment of risk that should be verified by more detailed modelling (CFD). These scenarios can also be used for a quick estimation of areas endangered by an incident or accident. The results of modelling of the hazardous zones contribute to a reduction in risk of major accidents associated with these potential alternative energy sources. 相似文献
630.
基于改进VRP模型的危险品配送路径优化及其求解研究 总被引:1,自引:0,他引:1
吕品 《中国安全生产科学技术》2011,7(11):87-91
危险品道路运输高风险性,一直受到人们的广泛关注。危险品道路运输路径优化的研究,对于降低运输风险具有十分重要的意义。本文针对危险品运输配送过程中的路径优化问题,提出综合考虑道路运输的风险和费用两方面指标改进VRP模型路径优化目标,并设计遗传算法对改进模型进行了求解。最后通过实例进行了验证。结果表明:用遗传算法对改进VRP模型的求解结果与实际分析结果相符。因此,改进VRP模型及其遗传算法求解设计可以应用于危险品运输的路径优化分析。 相似文献