全文获取类型
收费全文 | 1467篇 |
免费 | 158篇 |
国内免费 | 241篇 |
专业分类
安全科学 | 253篇 |
废物处理 | 20篇 |
环保管理 | 176篇 |
综合类 | 820篇 |
基础理论 | 217篇 |
污染及防治 | 78篇 |
评价与监测 | 115篇 |
社会与环境 | 110篇 |
灾害及防治 | 77篇 |
出版年
2024年 | 6篇 |
2023年 | 18篇 |
2022年 | 48篇 |
2021年 | 71篇 |
2020年 | 63篇 |
2019年 | 71篇 |
2018年 | 51篇 |
2017年 | 71篇 |
2016年 | 86篇 |
2015年 | 75篇 |
2014年 | 88篇 |
2013年 | 105篇 |
2012年 | 118篇 |
2011年 | 102篇 |
2010年 | 75篇 |
2009年 | 75篇 |
2008年 | 64篇 |
2007年 | 101篇 |
2006年 | 81篇 |
2005年 | 59篇 |
2004年 | 53篇 |
2003年 | 48篇 |
2002年 | 46篇 |
2001年 | 42篇 |
2000年 | 30篇 |
1999年 | 31篇 |
1998年 | 34篇 |
1997年 | 28篇 |
1996年 | 25篇 |
1995年 | 22篇 |
1994年 | 14篇 |
1993年 | 16篇 |
1992年 | 16篇 |
1991年 | 14篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 2篇 |
1977年 | 2篇 |
1973年 | 2篇 |
排序方式: 共有1866条查询结果,搜索用时 193 毫秒
971.
Thomas G. Bobick Author Vitae E.A. McKenzie Jr. Author Vitae Author Vitae 《Journal of Safety Research》2010,41(3):203-211
Introduction
Fall-related occupational injuries and fatalities are serious problems in the U.S. construction industry, especially incidents related to unguarded holes. The National Institute for Occupational Safety and Health, Division of Safety Research, Morgantown, WV conducted a project to evaluate the effectiveness of guardrail systems to prevent falls through roof and floor holes.Methods
Two commercial edge-protection products were evaluated when used as perimeter guarding around a roof hole. Installations of the commercial products were compared to job-built guardrails constructed of 2″ × 4″ construction-grade lumber. Occupational Safety and Health Administration (OSHA) regulations require that “a force of at least 200 pounds” must be supported by the top rail of a guardrail system “in any outward or downward direction at any point along the top edge.” A laboratory testing system was developed to evaluate this requirement. A dynamic 200-lb force was generated against the top rail using a weighted manikin mounted on a hinged steel frame. Nine construction workers, who served as test subjects, each built five different guardrail configurations.Results
All 45 configurations met the 200-lb OSHA requirement. Installation time for one commercial product was 32% quicker than the job-built configuration (25.6 min vs. 37.9 min).Impact on Industry
This study: (a) indicates that the two edge-protection products can be used as perimeter guarding; (b) highlights the importance of using proper materials and fasteners to construct guardrails to protect workers from falling into unguarded roof and floor holes; and (c) discusses an overall-strength-testing methodology that can be used by fall-protection researchers. 相似文献972.
Fisher判别法在煤与瓦斯突出危险程度预测中的应用 总被引:1,自引:0,他引:1
高卫东 《中国安全科学学报》2010,20(10)
为了提高煤与瓦斯突出的预测精度,根据煤与瓦斯突出的综合作用假说,选取开采深度、瓦斯压力、瓦斯放散初速度、煤的普氏系数以及煤体破坏类型作为判别指标。利用国内典型突出矿井20个实测数据作为训练样本,建立煤与瓦斯突出危险程度预测的Fisher判别分析模型,并应用于其他待判样本的预测。结果表明:Fisher判别分析模型能够反映多因素对煤与瓦斯突出的影响,分类性能良好,误判率低,借助SPSS软件实现,具有计算简单的特点,是煤与瓦斯突出预测的一种有效方法。 相似文献
973.
974.
975.
976.
Economic Growth and Marine Biodiversity: Influence of Human Social Structure on Decline of Marine Trophic Levels 总被引:2,自引:0,他引:2
Abstract: We assessed the effects of economic growth, urbanization, and human population size on marine biodiversity. We used the mean trophic level (MTL) of marine catch as an indicator of marine biodiversity and conducted cross-national time-series analyses (1960–2003) of 102 nations to investigate human social influences on fish catch and trends in MTL. We constructed path models to examine direct and indirect effects relating to marine catch and MTL. Nations' MTLs declined with increased economic growth, increased urbanization, and increased population size, in part because of associated increased catch. These findings contradict the environmental Kuznets curve hypothesis, which claims that economic modernization will reduce human impact on the environment. To make informed decisions on issues of marine resource management, policy makers, nonprofit entities, and professional societies must recognize the need to include social analyses in overall conservation-research strategies. The challenge is to utilize the socioeconomic and ecological research in the service of a comprehensive marine-conservation movement. 相似文献
977.
Linked river basin and coastal water models were applied to analyse the effects of an optimal nitrogen management scenario
in the Oder/Odra river basin on water quality in the Oder (Szczecin) Lagoon and the Pomeranian Bay (Baltic Sea). This scenario
would reduce nitrogen loads into the coastal waters by about 35%, a level which is similar to the load of the late 1960’s.
During summer the primary production and algae biomass in the Oder estuary is limited by nitrogen, which makes a nitrogen
management reasonable. The comparison of the late 1960’s and the mid 1990’s shows that an optimal nitrogen management has
positive effects on coastal water quality and algae biomass. However, this realistic nitrogen reduction scenario would not
ensure a good coastal water quality according to the European Water Framework Directive. A good water quality in the river
will not be sufficient to ensure a good water quality in the lagoon. Nitrogen load reductions bear the risk of increased potentially
toxic, blue-green algae blooms, especially in the Baltic coastal sea. However, to reach water quality improvements in lagoons
and inner coastal waters, nitrogen cuts are necessary. A mere focus on phosphorus is not sufficient. 相似文献
978.
Sea-level rise and coastal vulnerability: an assessment of Andhra Pradesh coast,India through remote sensing and GIS 总被引:2,自引:1,他引:1
K. Nageswara Rao P. Subraelu T. Venkateswara Rao B. Hema Malini R. Ratheesh S. Bhattacharya A. S. Rajawat Ajai 《Journal of Coastal Conservation》2008,12(4):195-207
The eustatic sea-level rise due to global warming is predicted to be about 18 to 59 cm by the 2100 (IPCC 2007), which necessitates identification and protection of vulnerable sections of coasts. Assessment of vulnerability level of
Andhra Pradesh (AP) coast as an example is demonstrated in this study using five physical variables, namely coastal geomorphology,
coastal slope, shoreline change, mean spring tide range, and significant wave height. A coastal vulnerability index was prepared
by integrating the differentially weighted rank values of the five variables, based on which the coastline is segmented into
low-, moderate-, high-, and very high risk categories. About 43% of the 1,030-km-long AP coast is under very high-risk, followed
by another 35% under high-risk if the sea level rises by ~0.6 m displacing more than 1.29 million people living within 2.0 m
elevation in 282 villages in the region. 相似文献
979.
Michael E. Fraker 《Behavioral ecology and sociobiology》2008,62(7):1201-1205
The activity level of prey reflects a trade-off between predation risk and foraging gain. A number of theoretical and empirical
studies have shown that a prey's energetic state or the level of its resource should influence this trade-off (i.e., what
the optimal activity level at a level of predation risk is). Here, I show that the energetic state of prey may also influence
the duration of their antipredator behavioral response. Green frog tadpoles (Rana clamitans) reduced their activity level for a shorter time during exposure to the chemical cue of predatory larval dragonflies (Anax spp.) as their time since last feeding increased (i.e., as their energetic state decreased). Interestingly, the tadpoles
strongly reduced their activity level upon cue exposure in all treatments. Thus, the relative activity level of tadpoles at
different energetic states varied over time. 相似文献
980.
报道了1988年-1995年浙江省建筑材料中放射性水平和所致居民剂量的计算结果。采用高纯锗γ能谱法测定了该地区的6种,139个建筑材料样品中放射性核素含量,并收集了1984年以前该地区另外5种,77个建筑材料样品中的放射性水平数据。 相似文献