全文获取类型
收费全文 | 1933篇 |
免费 | 50篇 |
国内免费 | 337篇 |
专业分类
安全科学 | 87篇 |
废物处理 | 117篇 |
环保管理 | 122篇 |
综合类 | 681篇 |
基础理论 | 374篇 |
污染及防治 | 640篇 |
评价与监测 | 147篇 |
社会与环境 | 86篇 |
灾害及防治 | 66篇 |
出版年
2023年 | 27篇 |
2022年 | 81篇 |
2021年 | 73篇 |
2020年 | 43篇 |
2019年 | 45篇 |
2018年 | 73篇 |
2017年 | 71篇 |
2016年 | 91篇 |
2015年 | 89篇 |
2014年 | 142篇 |
2013年 | 211篇 |
2012年 | 158篇 |
2011年 | 163篇 |
2010年 | 120篇 |
2009年 | 103篇 |
2008年 | 117篇 |
2007年 | 111篇 |
2006年 | 100篇 |
2005年 | 60篇 |
2004年 | 43篇 |
2003年 | 45篇 |
2002年 | 44篇 |
2001年 | 32篇 |
2000年 | 27篇 |
1999年 | 22篇 |
1998年 | 25篇 |
1997年 | 23篇 |
1996年 | 20篇 |
1995年 | 19篇 |
1994年 | 12篇 |
1993年 | 15篇 |
1992年 | 9篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 7篇 |
1982年 | 6篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1967年 | 3篇 |
1965年 | 2篇 |
1964年 | 4篇 |
1961年 | 3篇 |
1960年 | 4篇 |
1959年 | 6篇 |
1958年 | 12篇 |
1957年 | 5篇 |
1956年 | 7篇 |
1955年 | 2篇 |
排序方式: 共有2320条查询结果,搜索用时 328 毫秒
431.
Characterizing effects of uncertainties in MSW composting process through a coupled fuzzy vertex and factorial-analysis approach 总被引:1,自引:0,他引:1
A coupled fuzzy vertex and factorial-analysis approach was developed in this study for systematically characterizing effects of uncertainties in a municipal solid waste composting process. A comprehensive composting process model was also embedded into the system framework and used to address substrate decomposition and biomass growth, as well as the interactions between moisture contents, temperatures, and oxygen concentrations. The applicability of the proposed method was verified through a custom-made pilot-scale composting system. Results from fuzzy simulation indicated that the fuzzy vertex method could effectively communicate implicit knowledge into dynamic simulations and thus provide valuable information for enhancing composting process control under uncertainty. The factorial analysis was effective in quantifying the proportion to which the uncertainty of each single or interactive effect of model parameters contributes to the overall uncertainty of the system outcomes. Thus, sensitive parameters that may lead to errors or unreasonable predictions can be determined. The proposed study system could not only be used in characterizing combined effects of uncertainties for composting processes, but was also applicable to many other environmental modelling systems. 相似文献
432.
Kraigher H Al Sayegh Petkovsek S Grebenc T Simoncic P 《Environmental monitoring and assessment》2007,128(1-3):31-45
Mycorrhiza is the main spatial and temporal linkage between different constituents in a forest ecosystem. The functional compatibility
and stress tolerance of ectomycorrhizal types is species specific, and therefore the information on the ectomycorrhizal community
structure can add to the understanding of processes in forest ecosystems and can also be applied as tools for bioindication
of pollution stress in forest soils. We have studied the effects of pollution (N and S) on trees and forest soils by: (1)
quantification of ECM types diversity as in situ indicators in forest stands, (2) determination and quantification of pollution-sensitive or -insensitive ECM types as passive
monitors, (3) root growth and development of ECM on nonmycorrhizal spruce seedlings, planted at the studied sites (active
monitors), and (4) ECM infection (a bioassay based on mycorrhizal inoculum potential) of seedlings in an experimental set-up
as ex situ testers. ECM species richness for Norway spruce trees (Picea abies) showed higher values in unpolluted sites than in polluted ones, while the differences were not significant for European
beech trees (Fagus sylvatica). As pollution-sensitive or -insensitive ECM species in spruce forests, we suggest Hydnum rufescens (sensitive) and Paxillus involutus (unsensitive). Mycorrhizal potential in Norway spruce seedlings as a bioassay for soil N and S pollution was effective, and
is suggested as an additional, standardized and widely comparable system in bioindication of soil pollution. 相似文献
433.
大气微生物与气象条件及大气污染物的灰色关联分析 总被引:4,自引:0,他引:4
根据大气微生物浓度、气象因子和大气污染理化因子的监测结果,应用灰色关联分析原理,分析研究大气微生物浓度与气象条件和大气污染物的关联程度,说明气象因子对各类微生物浓度的影响大于大气污染因子,特别是对耐高渗透压霉菌。 相似文献
434.
Seventeen sediment samples at three representative sites (the Yuqiao Reservoir, the Haihe River and the Haihe River Estuary) in Tianjin, northern China, were analyzed to investigate the pollution status, accumulation and mobility of mercury (Hg). The results show that the Haihe River has to be considered as moderate to strongly contaminated with Hg (2 < mean I(geo) = 2.35 < 3), where total Hg contents were ca. 3 to 24 orders of magnitude greater than the regional background value. The sediments collected near a coal-fired power plant in an urban area were found to have very high Hg concentrations, which were significantly related to Hg emissions from coal-fired utility boilers. In the Yuqiao Reservoir, the surface sediments have to be considered as unpolluted with Hg (mean I(geo) = -0.05 < 0) and the Haihe River Estuary sediments have to be considered as unpolluted to moderately polluted with Hg (0 < mean I(geo) = 0.18 < 1). Sediment-bound Hg in the Yuqiao Reservoir and the Haihe River Estuary was found to be predominantly associated with the organo-chelated phase of the sediment (38.3% and 50.5%, respectively). However, unlike the Yuqiao Reservoir and the Haihe River Estuary, Hg in the Haihe River sediments existed mainly as sulfide Hg and elemental Hg, which accounted for 54.2% and 30.7% of total Hg, respectively. The availability of this element seemed restricted. The majority of Hg contamination in the Haihe River sediments had been attributed to historic and modern atmospheric deposition and Hg released from the Haihe River sediments didn't seem to be an important pollutant pathway into the Haihe River Estuary. The results provide new insights into Hg contamination in this region. 相似文献
435.
湖泊富营养化与氮、磷及有机物含量过高密切相关,建立数字型营养物基准能够防止富营养化对水体指定用途造成影响.太湖流域是我国华东地区经济腹地,近年来流域内湖泊水质每况愈下,对其基准研究可为湖泊治理提供依据.详细介绍了压力响应关系法制定湖泊营养物基准的步骤,并将此方法运用到太湖流域营养物基准制定研究中.为满足大多数水体指定用途,研究中将该流域湖泊基本功能确定为娱乐、永生生物栖息地及饮用水,以此构建流域概念模型.选择压力变量为总氮(TN)、总磷(TP)和有机物,响应变量为叶绿素a(chl-a).用非参数分析法和线性回归法分别建立压力-响应模型,通过2种方法相互验证得到TN、TP和CODMn基准分别为0.593、0.067和4.092 mg/L. 相似文献
436.
利用淮河流域旱涝易发区的安徽省寿县农田下垫面陆气相互作用观测试验资料,重点分析观测期内CO2通量、能量交换和水汽输送的季节变化,并讨论了与此有关的辐射分量通量、下垫面反射率、波恩比、能量闭合守恒、土壤温度和土壤湿度的季节变化。结果表明:CO2通量、能量分配受地表农作物长势影响明显,其中,水稻灌浆、成熟期,被稻田吸收的CO2通量最大可超过2 mg.m-2.s-1,潜热通量达到正的极大值。稻田光合作用最旺盛时期吸收的CO2通量和释放的潜热通量均大于小麦田光合作用最旺盛时期的对应量。较大土壤热通量对应于较低的土壤水含量。试验观测期的下垫面平均反射率为0.14。作物生长期,稻田表面潜热是下垫面吸收能量的主要消费者,小麦田表面潜热和感热相当。能量闭合率ε的变化范围为0.4~1。 相似文献
437.
某火电厂亚临界锅炉墙式再热器蒸汽出口至屏式再热器联络管母管及排空气管接管座产生裂纹发生渗漏。通过对墙式再热器出口管道排空气管接管座裂纹特征、结构型式、管道现场布置情况、运行环境等方面进行综合分析,认为排空气管道安装布置不合理,无保温措施,导致冷凝水倒流,形成热疲劳裂纹并逐步延伸扩展。确认产生裂纹的原因后,优化管道安装布置、对接管座结构型式做出改进并对产生裂纹的管道进行了更换,改进后锅炉运行约1.8× 104 h后复检无缺陷。 相似文献
438.
石漠化是指在热带、亚热带湿润半湿润气候条件和岩溶极其发育的自然背景下,受人为活动干扰,使地表植被遭受破坏,造成土壤严重侵蚀,基岩大面积裸露,砾石堆积的土地退化现象,是石山地区土地退化的极端形式。 相似文献
439.
3株反硝化聚磷菌的分离与鉴定 总被引:5,自引:0,他引:5
通过烛缸法培养富集、分离,结合除磷试验、硝酸盐还原产气试验及异染颗粒和PHB颗粒染色辅助检验相结合的方法筛选,得到3株具有较高脱氮除磷效率的反硝化聚磷菌DNPA8, DNPA9和DNPA10。在富氮富磷培养基中培养48 h,各菌株的脱氮率均大于75%,除磷率均大于78%。采用多相分类的方法确定了3株反硝化聚磷菌的分类地位,DNPA8为嗜麦芽寡养单胞菌,DNPA9为水生丛毛单胞菌属首次发现的反硝化聚磷菌;DNPA10为约翰逊氏不动杆菌。该研究结果为富营养化水体的治理提供了有效的菌种资源。 相似文献
440.
Peidong Su Xiangyu Gao Junke Zhang Ridha Djellabi Bo Yang Qi Wu Zhen Wen 《Frontiers of Environmental Science & Engineering》2021,15(6):130