全文获取类型
收费全文 | 271篇 |
免费 | 6篇 |
国内免费 | 41篇 |
专业分类
安全科学 | 30篇 |
废物处理 | 5篇 |
环保管理 | 53篇 |
综合类 | 97篇 |
基础理论 | 62篇 |
污染及防治 | 27篇 |
评价与监测 | 27篇 |
社会与环境 | 11篇 |
灾害及防治 | 6篇 |
出版年
2023年 | 8篇 |
2021年 | 10篇 |
2020年 | 7篇 |
2019年 | 8篇 |
2018年 | 9篇 |
2017年 | 7篇 |
2016年 | 12篇 |
2015年 | 13篇 |
2014年 | 13篇 |
2013年 | 14篇 |
2012年 | 11篇 |
2011年 | 12篇 |
2010年 | 14篇 |
2009年 | 22篇 |
2008年 | 24篇 |
2007年 | 19篇 |
2006年 | 15篇 |
2005年 | 15篇 |
2004年 | 8篇 |
2003年 | 10篇 |
2002年 | 3篇 |
2001年 | 7篇 |
2000年 | 7篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 6篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有318条查询结果,搜索用时 15 毫秒
131.
城市富营养化河道复合酶-原位生物修复技术研究 总被引:6,自引:0,他引:6
研究了复合酶类生物激活物质对河道中微生物的作用机理,通过测定河道中微生物的生化呼吸线、细菌数、脱氢酶、纤维素酶、脲酶和磷酸酶的酶活性来表征生物激活物质对河道自净过程的促进作用。研究结果表明,复合酶污水净化剂对微生物活性具有激活作用,累积耗氧量明显增加,酶激活率达到14%~136%,有效增强了水体的自净能力。复合酶原位生物修复技术在上海、北京和福州等多条受严重污染的富营养化河道的工程应用表明,复合酶污水净化剂在不同的地域条件下均可发挥良好的作用,具有安全、高效和适用性广等特点。 相似文献
132.
Dany Garant Julian J. Dodson Louis Bernatchez 《Behavioral ecology and sociobiology》2005,57(3):240-244
Inbreeding has negative effects on individual and population performances. Therefore, enhancement of offspring genetic diversity is believed to play a major role in shaping mating systems. However, no study has clearly separated the direct effect of having multiple partners from the indirect effect of having more outbred offspring on the resulting reproductive success of individuals in the wild. In this study, we report significant associations between both multiple mating and within-individual genetic diversity of offspring, and an increased reproductive success of wild female Atlantic salmon, Salmo salar. Specifically, we found that females with a higher number of mates also have more outbred offspring (within-individuals), and that both of these characteristics increased their reproductive success expressed in terms of offspring surviving when combining all freshwater juvenile stages. Our findings also indicate that determinants of fitness are different among sexes as within-individual offspring genetic diversity was not a strong predictor of male reproductive success, while the number of mates was important. We also show that females mated with more outbred males than on average, which potentially increased their chances of producing outbred offspring. These results therefore suggest that there could be more important indirect genetic benefits of multiple mating for females than for males.Communicated by M. Abrahams 相似文献
133.
李衍 《中国特种设备安全》2013,(12):43-47
介绍超声相控阵扇形(s型)扫查法对焊缝实施全体积检测的优势:信号(色码幅度)实时显示,自动存储,特别是检测数据可三维(5D)显示,又可多视角观测,缺陷四定(定位、定性、定量、定级)更方便,符合国际权威法规ASME最新版(2011a)的有关要求。期盼UT人员能在日常焊缝检测中熟练运用相控阵三维可视化技术。 相似文献
134.
地面监测得到的近地面细颗粒物PM_(2.5)浓度较为精确,但数据覆盖范围相对较小,卫星遥感反演的气溶胶光学厚度(AOD)数据可以反映污染物浓度分布,具有范围大且速度快的特点,因此,大多数学者通过建立PM_(2.5)-AOD模型来实现卫星遥感监测PM_(2.5)浓度,并通过引入气象要素来优化模型.然而,气象要素的选择与引入往往对模型的精度有较大的影响,如何有效地选择对PM_(2.5)浓度影响较大的气象要素一直是PM_(2.5)-AOD模型中的关键问题.因此,本文基于华东地区2014—2015年的MODIS AOD和地面监测站的PM_(2.5)浓度数据,结合再分析气象资料,利用多元逐步线性回归方法建立PM_(2.5)-AOD模型,从由特定时刻、高度上的气象要素与随时间、高度变化的气象要素组成的气象要素集中,筛选出对因变量PM_(2.5)浓度有显著影响的关键气象要素.结果表明:在地域与季节双重尺度下的PM_(2.5)-AOD模型精度更高;相较于特定时刻高度的气象要素,随时间和高度变化的气象要素对PM_(2.5)-AOD模型的影响更为显著;在地域与季节双重尺度下,1000~850 hPa经向风速差、世界时0:00—6:00近地面温度差、850~600 hPa温度差、6:00边界层高度、12:00—18:00近地面压强差、1000~850 hPa温度差对模型影响较大,但应依据不同季节和不同地区的具体影响程度作为选择标准. 相似文献
135.
大气质量评价上海指数法的改进及应用 总被引:1,自引:0,他引:1
该研究将模糊数学应用于上海指数法,在评价函数中引入半梯形隶属函数和倍斜率隶属函数,提出模糊上海指数法,将此法应用于延安市的大气质量评价工人,欧几里德贴近度法和上海指法的结果进行比较表明,模糊上海指数法的评价结果是科学合理的,并利用地理信息系统Mapinfo制作出基于地理信息的城市大气质量评价图,使评价结果可视化,地图化。 相似文献
136.
137.
138.
Krishan P. Singh 《Journal of the American Water Resources Association》1972,8(4):813-824
ABSTRACT. The role of initial baseflow, or the baseflow at the beginning of storm precipitation, in modifying mathematical rainfall-runoff relations is analyzed by using data from 95 storms over a drainage basin in Illinois. A regression model is set up with total runoff, surface runoff, baseflow runoff, and peak flow as dependent variables, and storm precipitation, initial baseflow, effective and total storm durations, and highest and lowest temperatures during the storm as independent variables. Stepwise regression analyses show that storm precipitation and initial baseflow are the most important variables for making dependent variable estimates. The standard error estimates using only storm precipitation and initial baseflow as predictors show a seasonal trend with a peak in July, August, or September. An understanding of the role of baseflow as an indicator of average soil moisture condition over the basin can be of great help in short-term reservoir regulation and flood warning. 相似文献
139.
In this paper, a mathematical programming-based methodology is presented for the explicit inclusion of life cycle assessment (LCA) criteria as part of the strategic investment decisions related to the design and planning of supply chain networks. By considering the multiple environmental concerns together with the traditional economic criteria, the planning task is formulated as a multi-objective optimization problem. Over a long-range planning horizon, the methodology utilizes mixed integer modelling techniques to address strategic decisions involving the selection, allocation and capacity expansion of processing technologies and assignment of transportation links required to satisfy the demands at the markets. At the operational level, optimal production profiles and flows of material between various components within the supply chain are determined. As such, the formulation presented here combines the elements of the classical plant location and capacity expansion problems with the principles of LCA to develop a quantitative decision-support tool for environmentally conscious strategic investment planning. 相似文献
140.
Manuel E. Ortiz-Santaliestra María José Fernández-Benéitez 《Environmental pollution (Barking, Essex : 1987)》2010,158(3):934-940
The negative effects of pollution on amphibians are especially high when animals are additionally stressed by other environmental factors such as water salinity. However, the stress provoked by salinity may vary among populations because of adaptation processes. We tested the combined effect of a common fertilizer, ammonium nitrate (0-90.3 mg N-NO3NH4/L), and water salinity (0-2‰) on embryos of two Pelophylax perezi populations from ponds with different salinity concentrations. Embryos exposed to the fertilizer were up to 17% smaller than controls. Survival rates of embryos exposed to a single stressor were always below 10%. The exposure to both stressors concurrently increased mortality rate (>95%) of embryos from freshwater. Since the fertilizer was lethal only when individuals were stressed by the salinity, it did not cause lethal effects on embryos naturally adapted to saline environments. Our results underscore the importance of testing multiple stressors when analyzing amphibian sensitivity to environmental pollution. 相似文献