全文获取类型
| 收费全文 | 1078篇 |
| 免费 | 238篇 |
| 国内免费 | 20篇 |
专业分类
| 安全科学 | 222篇 |
| 废物处理 | 13篇 |
| 环保管理 | 124篇 |
| 综合类 | 395篇 |
| 基础理论 | 331篇 |
| 环境理论 | 1篇 |
| 污染及防治 | 88篇 |
| 评价与监测 | 16篇 |
| 社会与环境 | 116篇 |
| 灾害及防治 | 30篇 |
出版年
| 2025年 | 13篇 |
| 2024年 | 25篇 |
| 2023年 | 32篇 |
| 2022年 | 42篇 |
| 2021年 | 47篇 |
| 2020年 | 51篇 |
| 2019年 | 51篇 |
| 2018年 | 47篇 |
| 2017年 | 58篇 |
| 2016年 | 50篇 |
| 2015年 | 53篇 |
| 2014年 | 40篇 |
| 2013年 | 57篇 |
| 2012年 | 77篇 |
| 2011年 | 101篇 |
| 2010年 | 57篇 |
| 2009年 | 69篇 |
| 2008年 | 55篇 |
| 2007年 | 65篇 |
| 2006年 | 72篇 |
| 2005年 | 37篇 |
| 2004年 | 40篇 |
| 2003年 | 31篇 |
| 2002年 | 35篇 |
| 2001年 | 25篇 |
| 2000年 | 24篇 |
| 1999年 | 13篇 |
| 1998年 | 7篇 |
| 1997年 | 9篇 |
| 1996年 | 15篇 |
| 1995年 | 12篇 |
| 1994年 | 6篇 |
| 1993年 | 6篇 |
| 1992年 | 4篇 |
| 1991年 | 2篇 |
| 1990年 | 1篇 |
| 1988年 | 1篇 |
| 1987年 | 1篇 |
| 1986年 | 1篇 |
| 1984年 | 2篇 |
| 1981年 | 1篇 |
| 1980年 | 1篇 |
排序方式： 共有1336条查询结果，搜索用时 15 毫秒
71.
内燃机曲轴系振动响应的多体系统动力学分析方法 总被引：9，自引：0，他引：9
介绍了运用多体系统动力学进行内燃机曲轴系振动响应分析的方法.通过综合运用CAD建模、有限元分析以及机械系统仿真等技术,可以建立包括曲轴柔性体以及随曲轴一起转动的零件刚性体在内的整个曲轴系的模型,计算零件间的相互作用,分析曲轴的动态变形.建立了某车用内燃机曲轴系的多体系统动力学模型,并对其振动响应进行了计算. 相似文献
72.
喀斯特石山地区社会经济与生态环境可持续发展系统研究:以桂西北为例 总被引：7，自引：0，他引：7
本建立了广西西北部喀斯特石山地区可持续发展的系统动力学模型。并用DYNAMO程序预测了未来20年桂西北地区的人口、工业、农业、第三产业，生态环境，土地资源，社会总产值，人均国民收人等的动态变化趋势，结果显示，该地区由于人口，工业资产增加使物质和能源消耗增长太快，而对污染治理的投入又太少，导致桂西北地区的生存环境质量下降，因此应当加大对污染治理的投入力度，改善区域环境质量，这是实现息烽县区域可持续发展的关键，根据区域特点探讨了桂西北喀斯特贫困山区的形成演化，提出了可持续发展的途径。 相似文献
73.
The purpose of the research was to improve prediction of response of buildings to blast waves by including the negative phase and considering clearing of both positive and negative phases. Commonly used structural design practices, which trace their origins to military design manuals, often ignore the negative phase as well as positive phase clearing. For high explosive threats, this approach is conservative in most circumstances. However, negative phase clearing had not previously been studied for blast waves, and the implications for structural response had not been evaluated. This paper presents results of modeling negative phase blast clearing behavior for a typical blast wave and discusses the differences from positive phase clearing. The implications of including positive and negative phase clearing in building blast damage analysis are also investigated through single-degree-of-freedom (SDOF) analyses.Blast waves from explosion sources like a vapor cloud explosion (VCE), pressure vessel burst or high explosive exhibit both positive and negative phases, and the relative magnitude of the positive and negative phases varies among explosion sources and the specific circumstances of each source. A fully reflected blast wave is produced if an incident blast wave were to strike an infinitely tall and wide wall in a normal orientation. Both the positive and negative phases of the blast wave are enhanced by the reflection process. However, when an incident blast wave strikes a wall of finite size in a normal orientation, rarefaction waves are created at the edges of the wall, and the rarefactions sweep down from the roof and inward from sides. The rarefaction waves result in a clearing effect for both the positive and negative phases.Clearing relieves some of the applied blast load on the reflected wall for the positive phase. However, this is not always the case for the negative phase. As shown by the results presented in this paper, clearing may either relieve or enhance the applied negative phase blast load, depending on the duration of the blast wave and the wall dimensions.The impact of negative phase clearing on structural response for generic building components was also investigated. Nonlinear SDOF methods were used to characterize response in terms of peak positive and negative displacements. It was found that the influence of the negative phase is significant and the peak structural response can occur during negative (outward) displacement. 相似文献
74.
基于系统动力学的食品企业安全生产监管博弈研究 总被引：1，自引：0，他引：1
为了研究食品安全生产及监管的内在机理、影响因素及监管模式,采用演化博弈论方法建立了政府监管部门与食品企业之间的博弈模型,运用复制动态方程和系统动力学方法深入分析了食品安全生产中相关主体的决策选择。结果表明:食品企业在追求利益最大化的前提下须主动重视食品安全问题,食品企业的策略选择受安全生产投入成本、处罚成本和声誉收益的影响;政府监管部门的监管行为受监管成本、外部负效益及社会成本等多方因素的影响。因此,增大监管部门惩处力度、降低监管成本、完善社会公众监督机制、强化声誉效应是食品安全问题得以解决的有力保障。 相似文献
75.
76.
建筑火灾烟气中CO迁移规律的FDS模拟 总被引：2，自引：1，他引：2
以T型\"侧间-走廊\"典型建筑火灾为模拟对象,分析烟气在走廊中的水平和垂直流动特征,并对火源房门高低、走廊端头启闭和多房门启闭等场景使用火灾模拟软件(FDS)进行了模拟和远距离房间CO浓度的迁移规律的分析.结果表明:烟气从火源房间经拱腹溢出在走廊中形成受限空间的顶棚射流;门檐高度决定了CO能够在走廊中的迁移量;烟气在走廊远距离封闭端头形成上部的热烟气层,中部回流层和下层的补气层;其中中部烟气回流层的高低、流速和CO浓度是影响临近非火源房间CO浓度的重要因素.走廊启闭和多房门火灾场景的模拟结果也进一步证明了CO的迁移规律. 相似文献
77.
In recent years, significant progress has been made to ensure that process industries are among the safest workplaces in the world. However, with the increasing complexity of existing technologies and new problems brought about by emerging technologies, a strong need still exists to study the fundamentals of process safety and predict possible scenarios. This is attained by conducting the corresponding consequence modeling and risk assessments. As a result of the continuous advancement of Computational Fluid Dynamics (CFD) tools and exponentially increased computation capabilities along with better understandings of the underlying physics, CFD simulations have been applied widely in the areas of process safety and loss prevention to gain new insights, improve existing models, and assess new hazardous scenarios. In this review, 126 papers from 2010 to 2020 have been included in order to systematically categorize and summarize recent applications of CFD for fires, explosions, dispersions of flammable and toxic materials from accidental releases, incident investigations and reconstructions, and other areas of process safety. The advantages of CFD modeling are discussed and the future of CFD applications in this research area is outlined. 相似文献
78.
Hydrogen is considered an excellent clean fuel with potential applications in several fields. There are serious safety concerns associated with the hydrogen process. These concerns need to be thoroughly understood and addressed to ensure its safe operation. To better understand the safety challenges of hydrogen use, application, and process, it is essential to undertake a detailed risk analysis. This can be achieved by performing detailed consequence modellings and assessing risk using the computational fluid dynamics (CFD) approach. This study comprehensively reviews and analyses safety challenges related to hydrogen, focusing on hydrogen storage, transmission, and application processes. Range of release and dispersion scenarios are investigated to analyse associated hazards. Approaches to quantitative risk assessment are also briefly discussed. 相似文献
79.
Liquefied natural gas (LNG) has been largely indicated as a promising alternative solution for the transportation and storage of natural gas. In the case of accidental release on the ground, a pool fire scenario may occur. Despite the relevance of this accident, due to its likelihood and potential to trigger domino effects, accurate analyses addressing the characterization of pool fires of LNG are still missing.In this work, the fire dynamic simulator (FDS) has been adopted for the evaluation of the effects of the released amount of fuel and its composition (methane, ethane, and propane), on the thermal and chemical properties of small-scale LNG pool fire. More specifically, the heat release rate, the burning rate, the flame height, and thermal radiation, at different initial conditions, have been evaluated for pool having diameter smaller than 10 m. Safety distances have been calculated for all the investigated conditions, as well.Results have also been compared with data and correlations retrieved from the current literature. The equation of Thomas seems to work properly for the definition of the height over diameter ratio of the LNG pool fire for all the mixture and the investigated diameters.The addition of ethane and propane significantly affects the obtained results, especially in terms of radiative thermal radiation peaks, thus indicating the inadequacy of the commonly adopted assumption of pure methane as single, surrogate species for the LNG mixture. 相似文献
80.
采用连通法,针对甲烷复杂反应机理,成功地进行了不同水平的机理简化研究。通过建立组分依赖关系的正规化Jacobian矩阵,精确地查明了燃烧组分之间的耦合关系,分别构造出仅包含重要化学路径的两个动力学简化模型,获得的简化机理分别包含227和138个反应,分别涉及39和26种组分。通过对层流预混火焰结构的模拟,所得简化机理和原详细反应动力学机理关于火焰结构的计算吻合很好,计算结果显示,两个简化机理具有较高的模拟精度。 相似文献