全文获取类型
收费全文 | 919篇 |
免费 | 39篇 |
国内免费 | 355篇 |
专业分类
安全科学 | 69篇 |
废物处理 | 48篇 |
环保管理 | 71篇 |
综合类 | 490篇 |
基础理论 | 181篇 |
污染及防治 | 317篇 |
评价与监测 | 38篇 |
社会与环境 | 35篇 |
灾害及防治 | 64篇 |
出版年
2023年 | 27篇 |
2022年 | 56篇 |
2021年 | 40篇 |
2020年 | 30篇 |
2019年 | 29篇 |
2018年 | 34篇 |
2017年 | 44篇 |
2016年 | 42篇 |
2015年 | 65篇 |
2014年 | 71篇 |
2013年 | 95篇 |
2012年 | 76篇 |
2011年 | 105篇 |
2010年 | 84篇 |
2009年 | 53篇 |
2008年 | 71篇 |
2007年 | 50篇 |
2006年 | 53篇 |
2005年 | 49篇 |
2004年 | 32篇 |
2003年 | 25篇 |
2002年 | 25篇 |
2001年 | 20篇 |
2000年 | 19篇 |
1999年 | 26篇 |
1998年 | 20篇 |
1997年 | 12篇 |
1996年 | 15篇 |
1995年 | 21篇 |
1994年 | 9篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有1313条查询结果,搜索用时 531 毫秒
671.
Influence of aggregate pre-wetting and fly ash on mechanical properties of lightweight concrete 总被引:5,自引:0,他引:5
This study has examined the mechanical properties of lightweight aggregate concrete with a density of 1800 kg/m3. The effects of the following parameters on the concrete properties have been analyzed: the pre-wetting time of the lightweight aggregate and the percentage of pulverized fly ash used as cementitious replacement material. The strength of the lightweight aggregate was found to be the primary factor controlling the strength of high-strength lightweight concrete. An increase in the cementitious content from 420 to 450 kg/m3 does not significantly increase the strength of lightweight aggregate concrete. The relationship between the flexural and compressive strength at 28 days can be represented by the equation fr=0.69/fck. The elastic modulus was found to be much lower than that of normal weight concrete, ranging from 15.0 to 20.3 GPa. The addition of PFA increases the slump and density of lightweight aggregate concrete. 相似文献
672.
2005年6月16日,我国首家利用高科技手段和多种互动技术展示公共安全教育的“海淀公共安全馆”在北京建成并正式对外开放。 相似文献
673.
Debrisflowdisasterharmingcities/towns,trafficlinesandwaterconservancyisoneofthemostimportantdisastersandoneoftheprimaryfactorsofrestrictionofeconomicdevelop mentinwesternmountainareasofChina.Withtheimplementofwesterndevelopmentpro gram,mountaincities/townswillgrowrapidly.Theconflictionbetweenrapidgrowthofcities/townsinmountainareasanddeteriorationofdebrisflowwillbemoreserious,thusthere searchesonmitigationcountermeasuresarenecessaryfordevelopmentandconstructionofmountaincities/towns.Actualitya… 相似文献
674.
针对我国职业健康现状,依据预防为主的原则,论述了预防劳动疾病的重点和预防工作中的薄弱环节。提出了减少呼吸吸入引起的职业病的措施。 相似文献
675.
676.
爆炸及其危险性分析与评价 总被引:1,自引:0,他引:1
了解爆炸发生的机理,对危险场所进行爆炸危险性评价是预防爆炸事故发生的有效措施。本文对爆炸及典型的爆炸危险性评价方法进行了简略介绍。 相似文献
677.
1994年世界重要灾害地震32条(其中中国4条),因地震死亡者2400人(中国5人),受伤15500人(中国1149人),其中最严重的5次地震造成约320亿美元的经济损失。全球6级以上地震134次(其中7级以上地震15次),地震多发生于环太洋地震带,尤以西太平洋地区地震活动性较高,并有增强的趋势。 相似文献
678.
山东省地下水位下降引发的灾害及减灾对策 总被引:1,自引:0,他引:1
近二十年来山东省经济迅速发展与水资源匮乏的矛盾不断加剧。超量开采地下水导致地下水位持续的急剧下降,其结果引发了地裂缝、地面塌陷、海(咸)水入侵、生态环境恶化等一系列人为自然灾害。本文分析了这些灾害的基本特征并指出解决水资源不足是促进山东省经济持续高速发展并减轻地下水位下降灾害的根本措施。 相似文献
679.
680.
Effect of elemental sulphur on solubility of soil heavy metals and their uptake by maize 总被引:7,自引:0,他引:7
A pot experiment was conducted to study the influence of elemental sulphur (S) on solubility of soil Pb, Zn and Cd and uptake by maize (Zea mays L.). Two rates of elemental sulphur (S) applied at 0 (S0) and 200 (S200) mmol kg(-1) soil with three rates of each heavy metal at Pb, 0 (Pb0), 200 (Pb200), 400 (Pb400) mg kg(-1) soil, Zn, 0 (Zn0), 100 (Zn100), 200 (Zn200) mg kg(-1) soil and Cd, 0 (Cd0), 50 (Cd50), 100 (Cd100) mg kg(-1) soil, respectively. The result showed that with S application at 200 mmol S kg(-1), soil pH decreased about 0.3 unit and the solubility of the Zn and Cd was significantly increased, but the solubility of Pb had no significant influence. The concentration of Pb, Zn and Cd in maize shoots and roots were increased with increasing rates of heavy metals. However, the concentration of Zn and Cd in shoots and roots were higher with application of S rather than without S but no significant difference was found for Pb. The highest concentration of Zn in the shoots was 2.3 times higher with application of S rather than without at the same rate of Zn, 200 mg kg(-1). Plant biomass was also significantly affected by the application of S and of heavy metals. With heavy metal addition, the shoot and root biomass were decreased with the rates of those of heavy metals increased either with or without application of S. However, the shoot biomass was significantly decreased with S application at the same rate of heavy metals except that with Zn addition. The removal of Cd and Pb by maize uptake and accumulation with application of S had no significant increase compared to that without, but the removal Zn by maize uptake from the soil increased by application of S, 90.9 microg plant(-1) contrast to 25.7 microg plant(-1) at Zn200 within a growth period of only 40 days. 相似文献