全文获取类型
收费全文 | 3301篇 |
免费 | 361篇 |
国内免费 | 754篇 |
专业分类
安全科学 | 511篇 |
废物处理 | 44篇 |
环保管理 | 397篇 |
综合类 | 1958篇 |
基础理论 | 552篇 |
污染及防治 | 193篇 |
评价与监测 | 278篇 |
社会与环境 | 305篇 |
灾害及防治 | 178篇 |
出版年
2024年 | 11篇 |
2023年 | 76篇 |
2022年 | 104篇 |
2021年 | 139篇 |
2020年 | 128篇 |
2019年 | 124篇 |
2018年 | 104篇 |
2017年 | 171篇 |
2016年 | 206篇 |
2015年 | 205篇 |
2014年 | 191篇 |
2013年 | 266篇 |
2012年 | 364篇 |
2011年 | 352篇 |
2010年 | 247篇 |
2009年 | 209篇 |
2008年 | 169篇 |
2007年 | 219篇 |
2006年 | 217篇 |
2005年 | 164篇 |
2004年 | 112篇 |
2003年 | 95篇 |
2002年 | 77篇 |
2001年 | 62篇 |
2000年 | 69篇 |
1999年 | 61篇 |
1998年 | 35篇 |
1997年 | 38篇 |
1996年 | 35篇 |
1995年 | 27篇 |
1994年 | 36篇 |
1993年 | 27篇 |
1992年 | 12篇 |
1991年 | 20篇 |
1990年 | 13篇 |
1989年 | 7篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有4416条查询结果,搜索用时 15 毫秒
101.
县级地质灾害防治管理评价指标体系探讨 总被引:2,自引:4,他引:2
通过建立评价指标体系,尽可能定量地评价地质灾害防治管理工作,这是地质灾害防治管理工作科学化、规范化的有益补充.在分析建立县级地质灾害防治工作评价指标体系必要性、可行性的基础上,应用工作分析法和经验总结法征求了指标,运用AHP方法建立了评价指标体系结构,采用专家咨询法确定了权重,提出了一套由16个指标(含40项分指标)构成的较为完整的县级地质灾害防治管理工作评价体系.最后,应用所建立的评价指标体系对部分县进行了评价,验证了评价指标的准确性. 相似文献
102.
103.
中国水灾社会脆弱性评估方法的改进与应用--以长沙地区为例 总被引:17,自引:2,他引:17
中国是洪水灾害发生频繁的国家之一,研究水灾脆弱性对中国的灾害风险管理有重要的意义.但是,合理评估脆弱性尤其是社会脆弱性却面临着极大的挑战.论文对评估社会脆弱性指数的研究现状进行了分析,指出了传统评估方法存在的问题,并尝试改进Hoovering评估模式.选择湘江流域的长沙地区为研究区,应用改进模型对研究区进行了社会脆弱性指数的评估.结果表明,长沙地区社会脆弱性从1980年至2000年基本处于下降趋势,但是在2002年和2003年增长迅速.2003年,长沙5区4县中社会脆弱性指数最大的是开福区,其次是长沙县,而宁乡县的社会脆弱性指数最低. 相似文献
104.
105.
Quantifying and Evaluating Ecosystem Health: A Case Study from Moreton Bay, Australia 总被引:1,自引:0,他引:1
As part of the program monitoring the ecosystem health of Moreton Bay, Queensland, Australia, we developed a means for assessing
ecosystem health that allows quantitative evaluation and spatial representations of the assessments. The management objectives
for achieving ecosystem health were grouped into ecosystem objectives, water quality objectives, and human health objectives.
For the first two groups, aspects of the ecosystem (e.g., trophic status) were identified, and an indicator was chosen for
each aspect. Reference values for each indicator were derived from management objectives and compared with the mapped survey
values. Subregions for which the indicator statistic was equal to or better than the assigned reference value are referred
to as “compliant zones.” High-resolution surface maps were created from spatial predictions on a fine hexagonal grid for each
of the indicators. Eight reporting subregions were established based on the depth and predicted residence times of the water.
Within each reporting subregion, the proportion that was compliant was calculated. These results then were averaged to create
an integrated ecosystem health index. The ratings by a team of ecosystem experts and the calculated ecosystem health indices
had good correspondence, providing assurance that the approach was internally consistent, and that the management objectives
covered the relevant biologic issues for the region. This method of calculating and mapping ecosystem health, relating it
directly to management objectives, may have widespread applicability for ecosystem assessment. 相似文献
106.
Assessment of Soil Erodibility Indices for Conservation Reserve Program Lands in Southwestern Kansas Using Satellite Imagery and GIS Techniques 总被引:2,自引:0,他引:2
The soil erodibility index (EI) of Conservation Reserve Program (CRP) lands, which was the major criterion for CRP enrollment,
was assessed for six counties in southwestern Kansas using USGS seamless digital elevation model data and Geographical Informational
System techniques. The proportion of land areas with EI values of 8 or lower was less than 1% of the entire study area and
most of the land areas (72.5%) were concentrated on EI values between 8 and 24. Although land acreage with EI values of 24
or higher decreased dramatically, the proportion of CRP lands to the other land-use types did not change much from low to
high EI levels. The soil EI and physical soil characteristics of the CRP lands were compared to those of other land-use types.
In general, the mean EI values of the land-use types were strongly correlated with physical soil properties, including organic
matter content, clay content, available water capacity, permeability, and texture. CRP lands were compared in detail with
cropland in terms of their soil characteristics to infer the pivotal cause of the land transformation. Although there was
no significant statistical difference in EI between cropland and CRP soils, soil texture, soil family, and permeability were
statistically different between the two. Statistical analyses of these three variables showed that CRP soils had coarser texture
and higher permeability on average than cropland soils, indicating that CRP lands in the study area are drier than cropland
soils. Therefore, soil moisture characteristics, not necessarily soil erosion potential, might have been the key factor for
CRP enrollment in the study area. 相似文献
107.
土壤碳库管理指数(CPMI)是表征土壤碳库变化的一个重要量化指标,能够反映土壤的碳库变化和碳库质量。选取庐山8种森林植被类型土壤为研究对象,对其土壤有机碳库特征及碳库管理指数进行系统研究。结论表明:(1)土壤有机碳(SOC)主要分布于0~20 cm土层中,随着土层深度增加,不同森林植被类型下SOC含量急剧下降;在0~60 cm土层中,不同森林植被类型下SOC含量的平均值排序为:马尾松林常绿阔叶林灌丛针阔混交林常绿-落叶混交林黄山松林落叶阔叶林竹林。(2)不同森林植被类型下活性有机碳(ASOC)含量为0.24~0.57 g·kg–1,总有机碳(TOC)含量为9.72~14.74 g·kg–1,土壤碳库指数(CPI)为1.63~2.48,碳库活度(A)为0.019~0.062,碳库活度指数(AI)为0.388~1.265。不同森林植被类型下ASOC含量排序:落叶阔叶林黄山松林常绿-落叶阔叶混交林灌丛针阔混交林常绿阔叶林竹林马尾松林;不同森林植被类型下ASOC/TOC(%)排序:落叶阔叶林黄山松林常绿-落叶阔叶混交林竹林灌丛针阔混交林常绿阔叶林马尾松林;不同森林植被类型下CPMI排序为:落叶阔叶林黄山松林常绿-落叶阔叶混交林灌丛针阔混交林常绿阔叶林竹林马尾松林。 相似文献
108.
Textile dye effluents are believed to be toxic as they might exert various harmful effects on living organisms including genotoxicity. These effluents are the main source of direct and continuous input of pollutants into the aquatic ecosystems. In this study, dye effluents from a local silk dyeing industry were analysed for their genotoxic potential by the Allium cepa genotoxicity test. The A. cepa test is characterised as a genotoxicity test where the roots of A. cepa are grown in different concentrations of the test material. The macroscopic results clearly showed that the toxicity of the dye effluents prompted A. cepa root growth inhibition, and this effect increased with higher concentrations of the effluents. At the cellular level, no dividing cells were found at higher concentrations such as 60%, 80% and 100% of the effluents. However, at a lower concentration of 20%, dividing cells were identified, although the mitotic index was much lower than that of the control. Microscopic analysis showed that the dye effluents induced chromosomal aberrations at significant levels. Taken together, these results revealed that the textile dyeing industry effluents are toxic to eukaryotic cells and these dyes have genotoxic properties that can potentially lead to cancer development and adverse health conditions. 相似文献
109.
污染天气分型研究对空气质量预报、污染源总量控制等具有重要的意义。基于2013年1月~2014年12月高空及地面天气形势划分了成都市的天气类型并探讨各天气类型下的空气质量状况及其污染天气特征,以期为空气质量预报和预警提供依据。结果表明,空气污染过程中,500 hpa环流形势主要有两槽一脊型、一槽一脊型、纬向型、槽脊同位相型等,其中两槽一脊型和槽脊同位相型控制下的空气质量最差。发生空气污染时,地面环流形势可分为高压型、高压后部型、高压底部型、低压型、低压顶部型、低压前部型、低压底部型、鞍型场型、冷锋前部型和均压场型,其中高压型、高压底部型、高压后部型控制下的空气质量最差。 相似文献
110.
基于高频分时AQI及各污染物浓度数据,本文使用"AQI小时指数"、首要污染物等进行统计分析并建立VAR模型对关中城市群空气污染的总体情况、日内波动规律以及城市间空气污染的关联规律做了不同层次的挖掘。研究结果表明:(1)关中城市群的空气质量整体较差,春、冬季空气污染程度明显大于夏季,空气污染的"季节效应"和"集簇性"明显,且主要表现为颗粒物污染。(2)空气质量的日内波动规律在春、冬两季表现为下半天优于上半天,夏季夜间优于白天。但在不考虑四季AQI小时指数图"相位"差异的情况下,四季空气污染的日内波动呈现出明显的相似性。(3)各城市空气污染存在明显的关联规律。城市群内一个城市空气污染的恶化会加剧其他城市的空气污染,并且对其他城市空气污染的影响峰值会在24小时之内出现,且该影响会随着空间和时间尺度的增大而逐步衰减。 相似文献