全文获取类型
收费全文 | 179篇 |
免费 | 27篇 |
国内免费 | 61篇 |
专业分类
安全科学 | 61篇 |
废物处理 | 2篇 |
环保管理 | 12篇 |
综合类 | 96篇 |
基础理论 | 76篇 |
污染及防治 | 14篇 |
评价与监测 | 2篇 |
社会与环境 | 3篇 |
灾害及防治 | 1篇 |
出版年
2023年 | 7篇 |
2022年 | 7篇 |
2021年 | 12篇 |
2020年 | 11篇 |
2019年 | 17篇 |
2018年 | 11篇 |
2017年 | 19篇 |
2016年 | 19篇 |
2015年 | 9篇 |
2014年 | 14篇 |
2013年 | 24篇 |
2012年 | 8篇 |
2011年 | 16篇 |
2010年 | 7篇 |
2009年 | 7篇 |
2008年 | 12篇 |
2007年 | 14篇 |
2006年 | 8篇 |
2005年 | 7篇 |
2004年 | 9篇 |
2003年 | 2篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1983年 | 2篇 |
排序方式: 共有267条查询结果,搜索用时 17 毫秒
211.
为探究土壤中锰(Mn)污染对蔬菜食用安全性的影响,以上海市常见的4种蔬菜(青椒,CA;黄瓜,CS;豇豆,VU;菠菜,SO)为试验材料,采用温室盆栽土培试验方法研究了不同土壤Mn含量梯度下的蔬菜生物量变化以及各部位Mn转运累积特征,并基于各蔬菜食用安全分析了土壤中Mn的安全阈值。研究结果表明,Mn对4种蔬菜的生长均表现出低含量促进、高含量抑制现象,SO和VU对Mn的耐受度强于CA和CS。Mn主要富集在SO的茎叶,以及CA、CS和VU的茎叶和根部,可食部分中Mn含量大小排序为SO>VU>CS>CA。SO可食部分Mn含量与土壤Mn含量呈显著对数相关(P<0.01),其他3种蔬菜的可食部分Mn含量与土壤Mn含量均呈显著指数相关(P<0.01)。依据新鲜蔬菜中Mn食用安全限量值,推导出各蔬菜对应的土壤Mn安全阈值预测区间为:SO 992.5~1 097.3 mg·kg~(-1),VU 2 607.5~2 910.0 mg·kg~(-1),CS 3 147.5~3 494.6 mg·kg~(-1),CA3 618.0~3 921.5 mg·kg~(-1)。Mn污染土壤的安全利用应优先选择种植CA、CS和VU等低累积品种。 相似文献
212.
The effect of monoammonium phosphate (NH4H2PO4) particles on 5 μm aluminum dust flames is investigated experimentally and computationally. NH4H2PO4 in three particle size is employed to determine the inhibition efficiency on aluminum flame propagation. Flame inhibition mechanism considering both gas and surface chemistry of aluminum particles is developed. Results show that the inhibition effectiveness monotonously increases as NH4H2PO4 particle size is reduced to 25 μm. Flame morphology and flame microstructure change with the addition of different particle size NH4H2PO4. Small NH4H2PO4 particles within the range studied have a greater reduction in average flame propagation compared to the coarser one. Meanwhile, the fine NH4H2PO4 particles almost decompose completely during the penetration of aluminum flame and then undergo a sufficient chemical interaction with the flame. The simulations indicate that the decomposition products of NH4H2PO4 particles obstruct the oxidation of aluminum particles through flame radical consumption. Additionally, the addition of NH4H2PO4 can reduce the vaporization rate and surface reaction rate of aluminum particles. 相似文献
213.
城镇化对进城农民环保行为影响研究 总被引:1,自引:0,他引:1
改革开放以来,伴随中国经济的迅速增长和工业化进程提速,我国城镇化速度明显加快,之前较多的研究关注了城镇化对于我国资源和环境的压力,而较少有研究者从城镇化影响进城人口环保行为的微观视角来探讨城镇化对于降低环境压力的正向效应。采用中国社会综合调查2013年数据,本研究通过比较进城农民和留守农民环保行为的差异验证了城镇化对进城农民环保行为的影响,考虑到由选择性误差引起的内生性问题,本研究采用倾向值匹配的方法对内生性问题进行了修正,结果支持城镇化对进城农民环保行为的改善效应。另外,本研究发现进城农民和留守农民在私人领域的环保行为参与程度差距较大,而在公共领域环保行为参与程度差距较小。最后本研究提出了两个城镇化影响进城农民环保行为的中间机制并进行了初步验证:一是农村户籍居民进城后通过媒体接触,与城市居民互动获得更多环境知识进而改善自身环保行为,二是农民通过改善了环境关注水平,环境重要性认知等环境态度进而改善自身环保行为。本研究认为城镇化对于进城农民环保行为的正向影响对于降低城市环境压力有着积极的作用,因此公共决策部门应继续利用城市载体对规模人群的辐射效应,并不断通过政府引导、媒体宣传和社会参与来提升公众环保意识,营造出全民保护环境的城市社会环境进而不断改善公众环保行为。另外,针对进城农民在公共领域环保行为参与率较低的现状,城市政府既要不断提升进城农民的城市融入水平以改善进城农民对融入城市的环境关心水平,也应不断健全公共领域环保行为的参与机制以保障其参与渠道畅通。 相似文献
214.
高含固厌氧消化污泥流变特性 总被引:3,自引:0,他引:3
采用完全混合式反应器R1、R2和R3(搅拌频率分别设为不搅拌、每10 min转动5 min和每10 min转动8min),在序批式运行的状态下,考察了不同搅拌频率对高含固厌氧消化过程中污泥流变特性的影响,探究了污泥表观黏度降低的主要原因以及污泥流变特性与各项物化指标的关系。结果表明,各个反应器消化污泥表观黏度μ值在发酵的前4天均出现大幅降低,下降幅度依次达到73.3%、77.8%和80.0%,从厌氧装置设计和运行的角度来看,脱水污泥高含固厌氧消化具有可行性。各反应器消化污泥的含固率(total solid,TS)以及挥发性固体(volatile solid,VS)占TS的比例VS/TS与表观黏度μ值以及稠度系数K值呈现显著性的指数关系,而污泥颗粒中胞外聚合物(extracellular polymeric substance,EPS)的含量与污泥表观黏度之间的相关关系则较弱。厌氧消化的初始阶段,微生物(主要是水解菌与产酸菌)的作用是污泥黏度急剧降低的主要原因。 相似文献
215.
Jeremy L. Ringma Brendan Wintle Richard A. Fuller Diana Fisher Michael Bode 《Conservation biology》2017,31(5):1029-1038
Conservation fences are an increasingly common management action, particularly for species threatened by invasive predators. However, unlike many conservation actions, fence networks are expanding in an unsystematic manner, generally as a reaction to local funding opportunities or threats. We conducted a gap analysis of Australia's large predator‐exclusion fence network by examining translocation of Australian mammals relative to their extinction risk. To address gaps identified in species representation, we devised a systematic prioritization method for expanding the conservation fence network that explicitly incorporated population viability analysis and minimized expected species’ extinctions. The approach was applied to New South Wales, Australia, where the state government intends to expand the existing conservation fence network. Existing protection of species in fenced areas was highly uneven; 67% of predator‐sensitive species were unrepresented in the fence network. Our systematic prioritization yielded substantial efficiencies in that it reduced expected number of species extinctions up to 17 times more effectively than ad hoc approaches. The outcome illustrates the importance of governance in coordinating management action when multiple projects have similar objectives and rely on systematic methods rather than expanding networks opportunistically. 相似文献
216.
ABSTRACTIn this study, a Stirling engine with a free-displacer and a kinematically controlled power piston was proposed and analyzed from thermodynamic and dynamic points of view. The analysis intended to reveal the dynamic behaviors of moving components of the engine as well as predicting global thermal performance of it. A dynamic-thermodynamic mathematical model of the engine involving the isothermal gas pressure equation and motion equations of the displacer, power piston and crankshaft was developed. For the solution of the dynamic-thermodynamic model equations, and simulation of the engine’s running, a computer program was prepared in FORTRAN language. By considering a hot-end temperature of 1,000 K and a cold-end temperature of 350 K, dimensions of mechanic, volumetric and thermal components of the engine were quantified interactively. Variations of engine speed, engine power, displacer stroke, and engine torque were examined with respect to the spring constant, displacer mass, displacer damping constant and external load and, results were graphically presented. In comparison with engines having free-piston and kinematically driven displacer, the thermodynamic performance of the free-displacer engine was found to be lower. The engine was found to be able to work at constant speed and power. The values of the displacer mass and spring constant were optimized as 1,500 g and 1,30,000 N/s, respectively and the global speed of the engine was determined to be 47.75 Hz for these values. The effective and the indicated work of the engine were determined to be 113 and 126 J, respectively. 相似文献
217.
218.
Available cross-country, macro-level evidence regarding gender differences in environmental behaviors shows women are more environmentally concerned and responsive than men. However, while such macro-level evidence helps understand patterns of women’s environmental behaviors at a much broader level, it does not allow deeper insights into particular patterns at a single location or in much smaller areas. Tailor-made interventions needed to address livelihood and environmental strategies of poor rural women become meaningful if studies aim at revealing context specific, local variations in women’s environmental behaviors. In this context, there is only little research for Ethiopia regarding what influences women’s response to environmental problems. The objective of this research was to describe women’s response to environmental problems in Pawe Woreda and examine the demographic, socioeconomic, and institutional correlates of this response, with particular emphasis to forest resources. Data were primarily obtained from a sample of 363 households in a multi-stage sample survey and were analyzed mainly using a multivariate logistic regression model. We found that all except one of the demographic and socioeconomic variables included in the model were found to be statistically significant correlates of woman’s environmental response, but the institutional variable was not significantly associated with a woman’s environmental response. However, the qualitative result for additional institutional issues revealed the importance of land tenure. Many of the results are in line with the existing literature. 相似文献
219.
White lupin plants were grown in hydroponics with 0, 90 and 180 µmol L?1 Pb(II) ethylenediaminetetraacetate complex for 30 days. Pb distribution (shoot/root ratio) was 0.34 and 0.46 for both Pb treatments. In the shoots, no decrease in biomass nor in photosynthetic pigment levels and no changes in the concentrations of malondialdehyde and glutathione were detected. In the roots, malondialdehyde increased by 20%, glutathione 2–3.6 times and phytochelatin concentrations 4–5 times. The high tolerance of white lupin makes it a valuable plant for phytoremediation of Pb-contaminated soil. 相似文献
220.
磷与四价硒的共存对小白菜磷、硒吸收及转运的影响 总被引:5,自引:1,他引:4
采用土培盆栽试验和化学分析相结合的方法,研究了不同浓度磷酸盐与四价硒共存对小白菜生长、磷和硒吸收及转运的影响,旨在为安全有效地进行补硒和硒污染土壤的植物修复提供理论依据.结果表明,在供试硒浓度范围内(≤5.0 mg·kg-1),施磷均显著促进了小白菜的生长,表现为地上、地下部生物量的增大(p<0.01).与单施磷相比,硒与磷共存能抑制小白菜根系生长,且抑制其对磷的吸收.磷对小白菜硒吸收的影响与硒、磷浓度有关,表现为促进作用和抑制作用并存,当硒浓度较高时(≥2.5 mg·kg-1),与无磷对照相比施磷可促进小白菜根系对硒的吸收;但高磷处理却导致小白菜地下部硒浓度较低磷处理显著下降.小白菜对磷酸盐的选择性吸收要强于亚硒酸盐,且高浓度磷能抑制硒由小白菜地下部向地上部的转运.故在进行补硒或硒污染土壤修复时,应特别注意合理施磷,以免过量施磷对作物硒吸收和转运的影响. 相似文献