全文获取类型
收费全文 | 4720篇 |
免费 | 395篇 |
国内免费 | 410篇 |
专业分类
安全科学 | 1096篇 |
废物处理 | 62篇 |
环保管理 | 850篇 |
综合类 | 1821篇 |
基础理论 | 646篇 |
环境理论 | 2篇 |
污染及防治 | 172篇 |
评价与监测 | 288篇 |
社会与环境 | 343篇 |
灾害及防治 | 245篇 |
出版年
2024年 | 12篇 |
2023年 | 67篇 |
2022年 | 93篇 |
2021年 | 161篇 |
2020年 | 169篇 |
2019年 | 121篇 |
2018年 | 92篇 |
2017年 | 181篇 |
2016年 | 218篇 |
2015年 | 203篇 |
2014年 | 220篇 |
2013年 | 305篇 |
2012年 | 371篇 |
2011年 | 458篇 |
2010年 | 323篇 |
2009年 | 305篇 |
2008年 | 220篇 |
2007年 | 271篇 |
2006年 | 307篇 |
2005年 | 225篇 |
2004年 | 170篇 |
2003年 | 153篇 |
2002年 | 108篇 |
2001年 | 91篇 |
2000年 | 87篇 |
1999年 | 64篇 |
1998年 | 70篇 |
1997年 | 49篇 |
1996年 | 57篇 |
1995年 | 49篇 |
1994年 | 31篇 |
1993年 | 36篇 |
1992年 | 25篇 |
1991年 | 19篇 |
1990年 | 12篇 |
1989年 | 18篇 |
1988年 | 10篇 |
1987年 | 14篇 |
1986年 | 10篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1981年 | 14篇 |
1980年 | 11篇 |
1979年 | 15篇 |
1978年 | 8篇 |
1977年 | 7篇 |
1973年 | 10篇 |
1972年 | 12篇 |
1971年 | 6篇 |
排序方式: 共有5525条查询结果,搜索用时 15 毫秒
991.
Introduction
Generalized linear modeling (GLM), with the assumption of Poisson or negative binomial error structure, has been widely employed in road accident modeling. A number of explanatory variables related to traffic, road geometry, and environment that contribute to accident occurrence have been identified and accident prediction models have been proposed. The accident prediction models reported in literature largely employ the fixed parameter modeling approach, where the magnitude of influence of an explanatory variable is considered to be fixed for any observation in the population. Similar models have been proposed for Indian highways too, which include additional variables representing traffic composition. The mixed traffic on Indian highways comes with a lot of variability within, ranging from difference in vehicle types to variability in driver behavior. This could result in variability in the effect of explanatory variables on accidents across locations. Random parameter models, which can capture some of such variability, are expected to be more appropriate for the Indian situation.Method
The present study is an attempt to employ random parameter modeling for accident prediction on two-lane undivided rural highways in India. Three years of accident history, from nearly 200 km of highway segments, is used to calibrate and validate the models.Results
The results of the analysis suggest that the model coefficients for traffic volume, proportion of cars, motorized two-wheelers and trucks in traffic, and driveway density and horizontal and vertical curvatures are randomly distributed across locations.Conclusions
The paper is concluded with a discussion on modeling results and the limitations of the present study. 相似文献992.
Robin M. Pitblado John L. Woodward 《Journal of Loss Prevention in the Process Industries》2011,24(6):827-836
The authors have recently undertaken a major review of LNG consequence modeling, compiling a wide range of historical information with more recent experiments and modeling approaches in a book entitled “LNG Risk-Based Safety: Modeling and Consequence Analysis”. All the main consequence routes were reviewed – discharge, evaporation, pool and jet fire, vapor cloud explosions, rollover, and Rapid Phase Transitions (RPT’s). In the book, experimental data bases are assembled for tests on pool spread and evaporation, burn rates, dispersion, fire and radiation and effects on personnel and structures. The current paper presents selected highlights of interest: lessons learned from historical development and experience, comparison of predictions by various models, varying mechanisms for LNG spread of water, a modeling protocol to enable acceptance of newer models, and unresolved technical issues such as cascading failures, fire engulfment of a carrier, the circumstances for a possible LNG BLEVE, and accelerated evaporation by LNG penetration into water. 相似文献
993.
The probabilistic approach to the evaluation of fire hazard and the effectiveness of fire-precaution measures enables a rational response to the randomness of fire outbreaks. This article employs the statistical analysis methods to elucidate the causes for the ignition of fire on a random sample of industrial buildings in the Republic of Slovenia. The analyses are based on the Structural Equation Modeling (SEM), which is a well established and important statistical analysis technique in the fields of social science, biology, psychology and medicine, but hitherto rarely applied in safety research. The results of the study demonstrate that for the analyzed random sample of industrial buildings the frequency of fire outbreaks statistically significantly depends only on the presence and the probability of exposure to the heat sources (flames, sparks, and hot surfaces), but does not significantly depend on the available quantity of flammable materials within the industrial structure. 相似文献
994.
P.K. Marhavilas D.E. Koulouriotis 《Journal of Loss Prevention in the Process Industries》2011,24(5):671-687
The occupational accidents have a major impact upon human integrity and also bring about high costs for the social health and insurance system of a country. In addition, risk analysis is an essential process for the safety policy of a company, having as main aim the effacement of any potential of damage in a productive procedure, while the quantified risk evaluation is the most crucial part of the whole procedure of assessing hazards in the work. The main goal of this study is double: a) the development and presentation of a new hybrid risk assessment process (HRAP) and b) the application of HRAP in the Greek Public Power Corporation (PPC) (the unique electric power provider and the largest industry in Greece), by using occupational accidents that have been recorded, during the 12-year period of 1993-2004. The new process consists of four distinct phases a) the hazard sources’ identification phase, b) the risk consideration phase, c) the risk-evaluation phase, and d) the phase of the risk assessment and safety-related decision making. The results show that in some cases the risk value has been calculated in PPC to be higher than 500 (in the risk rating of 0-1000), which imposes the taking of suppressive measures for abolishing the danger source, while the fatal accident frequency rate (per 108 man-hrs) is FAFR ≅ 2.4. 相似文献
995.
基于模糊数学的机务维修中人的可靠性综合评价 总被引:1,自引:0,他引:1
基于有关资料数据统计、现场调查研究和理论分析,结合许多专家在人为因素上的研究成果,建立了机务维修中人可靠性评价指标体系,应用层次分析法(AHP)确定了各指标权重.运用模糊综合评价原理构建了机务中人的可靠性模糊综合评价模型,并进行了实例验证,得出了可靠性的综合评价等级.结果表明,该方法简单,易操作,能实现动态的综合评价,... 相似文献
996.
本文简迷了皮肤防护器材--化学防护服(衣)化学防护性能试验与评价用标准物质的重要性,系统地概述了外军化学防护服(衣)化学防护性能试验与评价用标准物质的研究现状,并提出了我国化学防护服(衣)防护性能试验与评价用标准物质研制过程中应注意的一些问题. 相似文献
997.
结合泥石流危险度和公路受泥石流损毁度两个指标,构建了天山公路泥石流风险评价模型,实现了对天山公路全线主要泥石流沟的风险值量化:风险值大于0.80的为极度危险,应以防为主,治为辅;风险值在0.50~0.80之间的为高度危险,应防、治并重;风险值在0.25~0.60之间的为中度危险,应以治为主,防为辅;风险值小于0.25的为轻度危险,应以防为主,治为辅。 相似文献
998.
999.
重大冰雪灾害应急管理能力的评价——以湖南省为例 总被引:1,自引:0,他引:1
针对重大冰雪灾害应急管理的复杂性,基于湖南冰雪灾害案例以及国内外自然灾害及其应急管理的相关文献,提出了重大冰雪灾害应急管理能力评价指标结构。运用熵权法和群决策方法确定指标综合权重,采用群决策方法获得专家群体对一级评价指标的综合偏好,形成评价城市的综合评价矩阵,运用灰色综合评价模型求出各个评价城市应急管理能力的排序向量。最后以湖南省冰雪灾害为案例进行了应用。 相似文献
1000.