全文获取类型
收费全文 | 1081篇 |
免费 | 160篇 |
国内免费 | 234篇 |
专业分类
安全科学 | 229篇 |
废物处理 | 77篇 |
环保管理 | 164篇 |
综合类 | 655篇 |
基础理论 | 92篇 |
环境理论 | 1篇 |
污染及防治 | 137篇 |
评价与监测 | 38篇 |
社会与环境 | 48篇 |
灾害及防治 | 34篇 |
出版年
2024年 | 5篇 |
2023年 | 33篇 |
2022年 | 53篇 |
2021年 | 63篇 |
2020年 | 69篇 |
2019年 | 40篇 |
2018年 | 43篇 |
2017年 | 50篇 |
2016年 | 58篇 |
2015年 | 46篇 |
2014年 | 67篇 |
2013年 | 88篇 |
2012年 | 78篇 |
2011年 | 93篇 |
2010年 | 66篇 |
2009年 | 54篇 |
2008年 | 47篇 |
2007年 | 68篇 |
2006年 | 72篇 |
2005年 | 58篇 |
2004年 | 53篇 |
2003年 | 58篇 |
2002年 | 37篇 |
2001年 | 37篇 |
2000年 | 33篇 |
1999年 | 17篇 |
1998年 | 23篇 |
1997年 | 23篇 |
1996年 | 8篇 |
1995年 | 11篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1988年 | 1篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1977年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有1475条查询结果,搜索用时 15 毫秒
821.
822.
基于物质流分析的密云水库上游流域磷循环特征 总被引:5,自引:3,他引:5
运用物质流分析方法,对北京市地表饮用水源地--密云水库流域进行了磷循环特征的研究;分析了研究区域内种植业、畜牧业、人口和简单子系统内部及子系统间的磷输入输出状况,以及系统整体的代谢效率特征,讨论了流域水体磷污染负荷的影响因素.研究结果表明:①化肥、饲料添加剂和农药是流域磷输入的主要来源,占直接物质磷输入总量的52.9%;整个系统向环境输入磷2868.44t,其中的26.5%直接进入水体.②在水体磷负荷中,畜牧业系统的贡献最大,为1800.26 t,达到输出总量的82%,其次为种植业系统,占9.4%.③系统整体结构不协调.呈现单向和开放状态.研究区种植业系统运行出现磷亏缺,并具有区域性和不均衡性的特点;而畜牧业系统则出现磷盈余,整体结构不协调;畜禽的排泄物未能得到有效处置和循环再生,其中进入水体的量占畜禽粪尿磷总量的40.9%,从而造成严重的资源浪费和广泛的生态环境影响.④水体污染负荷与城市化率密切相关. 相似文献
823.
How does agricultural intensification modulate changes in plant community composition? 总被引:1,自引:0,他引:1
Laura José-María José M. Blanco-MorenoLaura Armengot F. Xavier Sans 《Agriculture, ecosystems & environment》2011,145(1):77-84
Agricultural intensification, at local and landscape scales, has caused a decrease in plant diversity and changes in species composition in cereal fields. To better understand the role of landscape complexity and farming systems in shaping plant assemblages, it is of interest to focus on functional traits rather than on floristic composition, which may help to highlight trends in vegetation patterns. We analysed the relative abundance of various functional attributes (different life forms, growth forms, wind-pollinated species and wind-dispersed species) at three contrasted field positions (boundary, edge and centre) of 29 organic and 29 conventional cereal fields distributed in 15 agrarian localities of NE Spain. Agricultural intensification affected the biological attributes of the vegetation in dryland Mediterranean cereal fields; local factors (farming system and position) had a more prominent role in affecting plant functional composition than the surrounding landscape. Local factors were important for life form distribution, growth form and pollination type, whereas landscape complexity mainly affected the proportion of wind-dispersed species. Therefore, depending on the objective of the study, it is important to select functional attributes sensitive to the different scales of agricultural intensification, especially because landscape complexity and land-use intensity are commonly related. 相似文献
824.
双筒型微生物燃料电池产电及污水净化特性的研究 总被引:3,自引:0,他引:3
构建了双筒型微生物燃料电池并考察了产电和污水净化特性,在此基础上考察不同阳极填料对微生物燃料电池产电的影响.通过稳态放电法和电流中断法测量得到微生物燃料电池的内阻,以颗粒石墨作为阳极填料的双筒型微生物燃料电池内阻为38.9 Ω,阳极内阻、欧姆内阻和阴极内阻分别为5.1、 14.1和18.7 Ω,最大产电功率密度为6 253 mW/m3,双筒型微生物燃料电池的构型能有效提高单位体积质子膜面积.双筒型微生物燃料电池对COD的去除负荷为1.6 kg/(m3·d),库仑效率约为10%~12%.阳极填料为大颗粒石墨、小颗粒石墨、碳毡和穿孔型碳毡的双筒型微生物燃料电池的内阻分别为47、 39、 28和33 Ω,稳定运行周期分别为20、 18、 11和18 d.从兼顾产电和稳定运行角度出发,穿孔型碳毡和小颗粒石墨更适合用作MFC阳极填料. 相似文献
825.
Thilo Wellmann Erik Andersson Sonja Knapp Angela Lausch Julia Palliwoda Jrg Priess Sebastian Scheuer Dagmar Haase 《Ambio》2023,52(3):489
While held to be a means for climate change adaptation and mitigation, nature-based solutions (NbS) themselves are vulnerable to climate change. To find ways of compensating for this vulnerability we combine a focused literature review on how information technology has been used to strengthen positive social–ecological–technological feedback, with the development of a prototype decision-support tool. Guided by the literature review, the tool integrates recent advances in using globally available remote sensing data to elicit information on functional diversity and ecosystem service provisioning with information on human service demand and population vulnerability. When combined, these variables can inform climate change adaptation strategies grounded in local social–ecological realities. This type of integrated monitoring and packaging information to be actionable have potential to support NbS management and local knowledge building for context-tailored solutions to societal challenges in urban environments.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-022-01801-4. 相似文献
826.
A mathematical model for predicting thermal hazard data 总被引:2,自引:0,他引:2
Horng-Jang Liaw Ching-Chir Yur Yung-Fen Lin 《Journal of Loss Prevention in the Process Industries》2000,13(6):579-507
A systematic procedure and mathematical model for predicting thermal behavior is proposed. This model has been verified by experimental data. The results show that the model will predict thermal hazard behavior precisely. A procedure for predicting thermal hazard data is also developed. Some examples of predicting real behavior are simulated. 相似文献
827.
The Appellate Body report in January 2012 had supported the decision of Panel in the"China-measures related to the exportation of various raw materials"case(WT/DS394,395,398)and affirmed that China's restrictions(such as tariffs and quota measures)on the exportation of raw materials violated rules put forth by the WTO,which were required to be modified.In this case China's right to invoke Article 20 of GATT1994("general exception")to justify its exemption from the guidelines in Article 11.3 of the WTO Accession Protocol was denied by the Panel and the Appellate Body.This was due to the fact that the phrasing in Article 11.3 of Protocol failed to mention"GATT."This was the consequence of the two interpretation approaches the Dispute Settlement Body(DSB)adopted-a narrow textual interpretation and a subjective presumption of"legislative silence."The inappropriate use of the two methods of interpretation lead to an imbalance between the right and obligation of China under the additional obligations that were imposed upon China by the WTO,which create a negative impact on China's rare earth case and the protection of domestic natural resources. 相似文献
828.
C. Koroneos V. Karatsiori T. Grgič 《International Journal of Sustainable Engineering》2014,7(3):214-221
Buildings contribute almost half of the world's carbon dioxide (CO2) emissions. Energy and water consumption are some of the largest and fastest growing pressures on the global environment. The use of energy is mainly attributed to the heating and cooling of buildings. The type of materials used in the construction of buildings plays a significant role in the life-cycle emissions of each dwelling. Changing the material use in the construction of an existing building and adding insulation could have a major impact on energy use and the environment of the building in its entire life cycle. This paper investigates the amount of exergy savings and the decrease in CO2 emissions resulting from the refurbishing of an existing building in Ljubljana. This study results from the growing awareness that in the choice of building materials, the designer must consider not only the requirements of the owner and occupier of the building, but also the resulting energy savings, the resource base and the effects of the manufacturing and processing of building materials on the environment. The exergy efficiency of the material use is calculated and the environmental impact assessment of energy and material use is accounted for. 相似文献
829.
车用汽油、柴油有害物质是车用燃料品质的重要指标,而车用燃料品质直接关系到汽车污染物排放和大气污染状况,直接关系到我国第四、五阶段及更严格汽车排放标准能否有效实施和所有在用车的有效减排。研究车用汽油、柴油有害物质控制指标与控制途径对开展大气污染联防联控,有效控制我国城市和城市群大气污染有着重要意义。介绍了我国车用汽油、柴油有害物质控制指标制定的背景、国内外现行油品标准情况,提出了车用油品环境管理建议。 相似文献
830.
在飞机燃油箱内填充网状聚氨酯泡沫材料(以下简称“聚氨酯泡沫”)是一种十分有效的被动抑制损伤的防爆技术。但在飞机地面加油时,燃油与聚氨酯泡沫的高速冲刷与摩擦会产生静电并可能发生静电荷的积聚而使燃油带上高的静电电压,极有可能发生静电火花放电,威胁飞机安全。为了探寻填充聚氨酯泡沫燃油箱系统的静电电压积累规律,设计了简化的实验装置和测量系统,以几种较快的流速进行静电循环冲刷实验,并分类进行各项实验数据的整理和分析。通过Origin7.0软件采用非线性最小二乘法拟合(Levenbergmarquardt算法),编制了自定义参数初始化函数,完成了实验公式的参数求解。该参数估计不受人工干预,且拟合精度较高。通过实验和计算得到了填充聚氨酯泡沫燃油箱系统的静电电压积累数学表达式,基本符合静电电压经典物理公式。 相似文献