全文获取类型
收费全文 | 1620篇 |
免费 | 164篇 |
国内免费 | 377篇 |
专业分类
安全科学 | 364篇 |
废物处理 | 36篇 |
环保管理 | 211篇 |
综合类 | 925篇 |
基础理论 | 229篇 |
污染及防治 | 117篇 |
评价与监测 | 99篇 |
社会与环境 | 38篇 |
灾害及防治 | 142篇 |
出版年
2024年 | 5篇 |
2023年 | 24篇 |
2022年 | 49篇 |
2021年 | 88篇 |
2020年 | 53篇 |
2019年 | 54篇 |
2018年 | 41篇 |
2017年 | 69篇 |
2016年 | 78篇 |
2015年 | 106篇 |
2014年 | 89篇 |
2013年 | 92篇 |
2012年 | 144篇 |
2011年 | 136篇 |
2010年 | 95篇 |
2009年 | 121篇 |
2008年 | 85篇 |
2007年 | 119篇 |
2006年 | 122篇 |
2005年 | 113篇 |
2004年 | 74篇 |
2003年 | 60篇 |
2002年 | 56篇 |
2001年 | 56篇 |
2000年 | 45篇 |
1999年 | 33篇 |
1998年 | 25篇 |
1997年 | 27篇 |
1996年 | 15篇 |
1995年 | 20篇 |
1994年 | 16篇 |
1993年 | 8篇 |
1992年 | 11篇 |
1991年 | 10篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有2161条查询结果,搜索用时 15 毫秒
751.
752.
基于JC法尾矿坝稳定性可靠度研究 总被引:5,自引:2,他引:3
论述了可靠度理论在尾矿坝稳定性评价中可有效弥补定值法(安全系数法)存在的不足。文中选用JC法作为可靠度分析方法,结合实例对尾矿坝进行稳定性分析,分别求出了尾矿坝在正常和洪水工况下运行时的可靠度指标。并通过与定值法(安全系数法)比较,发现可靠度指标对坝体材料物理力学参数变异性的敏感度高于安全系数,因而得出可靠度方法可以更加全面、客观的反映出尾矿坝稳定性的真实状态。 相似文献
753.
Development of a Bird Integrity Index: Measuring Avian Response to Disturbance in the Blue Mountains of Oregon, USA 总被引:1,自引:0,他引:1
Bryce SA 《Environmental management》2006,38(3):470-486
The Bird Integrity Index (BII) presented here uses bird assemblage information to assess human impacts to 28 stream reaches
in the Blue Mountains of eastern Oregon. Eighty-one candidate metrics were extracted from bird survey data for testing. The
metrics represented aspects of bird taxonomic richness, tolerance or intolerance to human disturbance, dietary preferences,
foraging techniques, and nesting strategies that were expected to be positively or negatively affected by human activities
in the region. To evaluate the responsiveness of each metric, it was plotted against an index of reach and watershed disturbance
that included attributes of land use/land cover, road density, riparian cover, mining impacts, and percent area in clearcut
and partial-cut logging. Nine of the 81 candidate bird metrics remained after eliminating unresponsive and highly correlated
metrics. Individual metric scores ranged from 0 to 10, and BII scores varied between 0 and 100. BII scores varied from 78.6
for a minimally disturbed, reference stream reach to 30.4 for the most highly disturbed stream reach. The BII responded clearly
to varying riparian conditions and to the cumulative effects of disturbances, such as logging, grazing, and mining, which
are common in the mountains of eastern Oregon. This BII for eastern Oregon was compared to an earlier BII developed for the
agricultural and urban disturbance regime of the Willamette Valley in western Oregon. The BII presented here was sensitive
enough to distinguish differences in condition among stream riparian zones with disturbances that were not as obvious or irreversible
as those in the agricultural/urban conditions of western Oregon. 相似文献
754.
755.
当前,构建以渔民生态种养为主的生计转型长效机制,确保渔民“稳得住,能致富”是政府部门和学术界共同关注的重点。本文基于“生计恢复力”理论构建了“缓冲—自组织—学习”三维分析框架,借助必要条件分析(NCA)和模糊集定性比较分析(fsQCA)两种分析方法,从组态视角对长江退捕渔民生态种养采纳意愿的关键驱动条件、作用路径和潜在替代关系进行研究。研究发现:(1)NCA与QCA分析结果显示,单一条件无法形成渔民生态种养采纳意愿程度高的必要条件,但fsQCA组态分析显示,自组织能力尤其是对奖补惠及和政策新闻的关注能单独引致解释结果的产生。(2)渔民生态种养采纳意愿存在三种驱动路径,分别是自组织主导型、自组织—学习驱动型和缓冲—学习驱动型。同时,渔民生态种养采纳意愿存在三种抑制类型,分别是学习抑制型、自组织—学习抑制型及缓冲—自组织抑制型。(3)在特定条件下,自组织能力可以与其他两种能力的条件组合等效替代,以“殊途同归”的方式提升渔民生态种养采纳意愿。 相似文献
756.
Effect of oxidation treatment on the adsorption and the stability of mercury on activated carbon 总被引:1,自引:0,他引:1
HU Chang-xing ZHOU Jin-song LUO Zhong-yang HE Sheng WANG Guang-kai CEN Ke-fa 《环境科学学报(英文版)》2006,18(6):1161-1166
Oxidation treatment on the adsorption and the stability of Hg on activated carbon (AC) was inrestigated. Both MnO2-AC and FeCl3-AC were produced during oxidation treatment. The measurement of modified AC's mercury adsorption capacity was conducted in a simulated coal-fired flue gas by adsorbing test apparatus. TCLP and column leaching methods were used to test the stability of mercury adsorbed on ACs. The results indicate that the oxidation treatment changed the pore structure of the AC and modified the carbon surface by creating chemical components such as MnO4^-, Mn^4+, O, NO^3-, Fe^3+, Cl^-, etc. The Hg sorption capacity on MnO2-AC or FeCl3-AC was about three times higher than that of untreated carbon. In addition, the mercury control cost of each of the formers was about the half cost of the untreated carbon. The stability of Hg absorption was studied, it found that mercury adsorbed on the oxidation treated AC was not better than that of untreated carbon. It could concluded that the insoluble form of Hg is very important to the stability of mercury adsorbed on AC. This study suggests that the FeCl3-AC is the best absorbent for Hg with high adsorption capacity, better Hg adsorption stability in leaching environment, and lower cost among the three ACs tested. 相似文献
757.
758.
759.
三峡工程全面蓄水在即,库水位周期性的变动必定引起大范围的塌岸。以巴阳移民新村库岸为例,选取典型剖面,根据饱和—非饱和渗流理论,应用GEO-SLOPE软件分析了水位变动条件下库岸渗流场变化,进一步分析了库岸稳定性的变化趋势,并选用卡丘金法和极限平衡搜索法对塌岸范围进行了预测。结果表明:在蓄水至145m1、56 m1、75 m及175 m骤降至145 m四种工况中,随着库水位的上升,库岸稳定性有下降的趋势,在库水从175m骤降至145 m时稳定系数最低,预测塌岸范围24.5 m和29.5 m,为移民区土地利用提供了科学的依据。 相似文献
760.
从溶解氧含量变化分析博斯腾湖水质现状 总被引:2,自引:0,他引:2
通过对博斯腾湖2002 - 2006年水质溶解氧含量变化的分析研究,得出博斯腾湖水位下降,水质溶解氧含量呈下降趋势,博斯腾湖的部分区域有富营养化的趋势的结论.并提出合理调配用水量、在湖周边保持适量的湿地、利用外力加速水质的循环等对策和建议. 相似文献