全文获取类型
收费全文 | 1163篇 |
免费 | 186篇 |
国内免费 | 270篇 |
专业分类
安全科学 | 273篇 |
废物处理 | 14篇 |
环保管理 | 108篇 |
综合类 | 569篇 |
基础理论 | 200篇 |
污染及防治 | 98篇 |
评价与监测 | 38篇 |
社会与环境 | 47篇 |
灾害及防治 | 272篇 |
出版年
2024年 | 6篇 |
2023年 | 25篇 |
2022年 | 58篇 |
2021年 | 69篇 |
2020年 | 61篇 |
2019年 | 66篇 |
2018年 | 50篇 |
2017年 | 47篇 |
2016年 | 72篇 |
2015年 | 69篇 |
2014年 | 87篇 |
2013年 | 109篇 |
2012年 | 107篇 |
2011年 | 118篇 |
2010年 | 95篇 |
2009年 | 80篇 |
2008年 | 60篇 |
2007年 | 91篇 |
2006年 | 54篇 |
2005年 | 49篇 |
2004年 | 45篇 |
2003年 | 37篇 |
2002年 | 32篇 |
2001年 | 19篇 |
2000年 | 23篇 |
1999年 | 13篇 |
1998年 | 12篇 |
1997年 | 9篇 |
1996年 | 9篇 |
1995年 | 9篇 |
1994年 | 9篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有1619条查询结果,搜索用时 31 毫秒
801.
802.
The paper deals with hurricane Katrina, which hit the Gulf coast of the US at the end of August 2005, with disastrous consequences. The paper sketches the chronicle of the main events and deals with preparation and response in New Orleans, exploring the connection between knowledge and disaster management policies, in particular communication policy. The main failures in applying and sharing available information for preventing and limiting damage are attributed to lack of coordination between elected officials, authorities and agencies at all levels. The critical role of the media in shaping the perception of the event and the immediate response to it is also highlighted. 相似文献
803.
本文从煤矿企业生产经营和技术的特点出发,用总资产收益率及增长率与每元经营现金流量及增长率,来定量描述企业成长性的量的表现,从而构造了企业成长性评价指标体系和综合评价方法,定量地测度企业成长性。用企业技术五要素结构分析方法,具体研究了煤矿企业的技术结构,用未确定测度理论定量测度企业技术含量及增长率,来描述煤矿企业成长性的质的表现。根据煤矿企业的特点,研究煤矿企业的成长性及其建立适合煤炭评价指标和方法,为矿业企业可持续发展进行理论指导。 相似文献
804.
Ellen L. Petticrew Philip N. Owens Timothy R. Giles 《Water, Air, & Soil Pollution: Focus》2006,6(5-6):647-656
In August of 2003 a severe wildfire burnt the majority of Fishtrap Creek, a 170 km2 catchment in central British Columbia, Canada. The objective of this study was to determine the short-term (15-month) influence
of the wildfire on the amount and composition of fine sediment delivery and retention in the system and to compare it to a
similar unburnt catchment. In the spring of 2004 automatic water samplers were installed at a gauging site on Fishtrap Creek
to collect suspended sediments from the snowmelt runoff and gravel traps were deployed on the channel bed surface to collect
composite samples of suspended fine sediment. Jamieson, the reference creek, exhibits similar geology and pre-burn vegetation
and was sampled in the same manner for comparison. Composite suspended sediment collected in the traps was removed from the
streams in mid-summer and early September. Quantitative estimates of the amount and particle size structure of the naturally
stored fine sediment in, and on, the gravel creekbed were obtained in pre-melt, mid and late-summer conditions. Estimates
of suspended sediment yields indicated that while the burnt system delivered 66% more material per unit area, the total seasonal
suspended sediment yield was low (855 kg km−2) compared to other fire-disturbed systems. While the burnt catchment was primed to deliver sediment, the hydrologic drivers
were not of sufficient magnitude to generate a substantial response, suggesting that in this first post-fire year the system
was transport-limited, not supply-limited. Differences were noted in the spatial and seasonal composition of the <500 more
OM% composite suspended sedimentswith the burnt catchment having significantly (P≤0.05) more OM%. Seasonally a significant
increase of OM% in late summer samples was associated with instream biofilms and possible delivery of black carbon. The system’s
post-fire response was not geomorphically substantial but significant biological differences were noted in the short-term. 相似文献
805.
806.
地震作用下列车过桥安全性分析 总被引:3,自引:1,他引:3
通过建立的地震荷载作用下车桥系统动力响应分析模型,对不同的高速列车在典型地震荷载作用下通过秦沈客运专线上多跨双线简支箱梁桥的全过程进行了仿真分析,对影响地震发生时高速铁路常用跨度简支梁桥动力响应行为和车辆运行安全的主要因素进行了分析和研究,其结果表明增大桥梁结构的阻尼比可有效改善桥梁本身的抗震性能,但对提高列车在地震时过桥的安全性意义不大;地震作用使车体的横向振动加速度以及脱轨系数、轮重减载率和横向轮轨力等各项安全评价指标均随列车速度的提高而增大,因此,在评价地震作用下高速铁路简支梁桥上列车的走行安全性时,必须考虑列车运行速度的影响;给出了确保地震发生时高速列车在桥上安全运行的临界速度限值。 相似文献
807.
基于GIS的多模式重大危险源监控系统的研究 总被引:4,自引:8,他引:4
重大危险源的动态监控是安全保障和环境保护的重要技术环节,地理信息科学与技术的发展为实现重大危险源动态监控奠定了基础。笔者分析GIS在重大危险源现场环境浓度监测与预警、现场应急救援管理、重大危险源信息管理和事故趋势预测等子系统中应用的技术可行性;在扩展重大危险源管理信息系统基本功能的基础上增加监视和控制功能;为青岛市某化肥厂成功开发了具有监视监测、预报预警、应急辅助决策和处置工艺等一系列模块,涵盖安全保障的预防、预警、应急和处置的各个环节的多模式重大危险源监控系统。实现了多参数实时监控、自动预警和应急辅助决策。 相似文献
808.
Based on the developed neural-fuzzy control system for anaerobic hybrid reactor (AHR) in wastewater treatment and biogas
production, the neural network with backpropagation algorithm for prediction of the variables pH, alkalinity (Alk) and total volatile
acids (TVA) at present day time t was used as input data for the fuzzy logic to calculate the influent feed flow rate that was applied
to control and monitor the process response at di erent operations in the initial, overload influent feeding and the recovery phases. In
all three phases, this neural-fuzzy control system showed great potential to control AHR in high stability and performance and quick
response. Although in the overloading operation phase II with two fold calculating influent flow rate together with a two fold organic
loading rate (OLR), this control system had rapid response and was sensitive to the intended overload. When the influent feeding rate
was followed by the calculation of control system in the initial operation phase I and the recovery operation phase III, it was found that
the neural-fuzzy control system application was capable of controlling the AHR in a good manner with the pH close to 7, TVA/Alk <
0.4 and COD removal > 80% with biogas and methane yields at 0.45 and 0.30 m3/kg COD removed. 相似文献
809.
通过对应急响应手册2008版与2000版进行比较,找出2008版修订的内容,对于增加的内容进行了详细介绍。 相似文献
810.