全文获取类型
收费全文 | 1353篇 |
免费 | 123篇 |
国内免费 | 224篇 |
专业分类
安全科学 | 200篇 |
废物处理 | 11篇 |
环保管理 | 213篇 |
综合类 | 707篇 |
基础理论 | 226篇 |
污染及防治 | 55篇 |
评价与监测 | 76篇 |
社会与环境 | 146篇 |
灾害及防治 | 66篇 |
出版年
2024年 | 5篇 |
2023年 | 30篇 |
2022年 | 53篇 |
2021年 | 62篇 |
2020年 | 54篇 |
2019年 | 47篇 |
2018年 | 50篇 |
2017年 | 59篇 |
2016年 | 49篇 |
2015年 | 62篇 |
2014年 | 59篇 |
2013年 | 72篇 |
2012年 | 85篇 |
2011年 | 113篇 |
2010年 | 75篇 |
2009年 | 103篇 |
2008年 | 67篇 |
2007年 | 89篇 |
2006年 | 85篇 |
2005年 | 58篇 |
2004年 | 60篇 |
2003年 | 49篇 |
2002年 | 39篇 |
2001年 | 48篇 |
2000年 | 39篇 |
1999年 | 34篇 |
1998年 | 22篇 |
1997年 | 23篇 |
1996年 | 15篇 |
1995年 | 15篇 |
1994年 | 12篇 |
1993年 | 13篇 |
1992年 | 14篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 4篇 |
1976年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有1700条查询结果,搜索用时 31 毫秒
991.
以城市总体规划为指导,对南京市声环境功能区划进行调整。根据相关技术规范,按照宜粗不宜细的原则,对城市和乡村功能区分别进行划分;明确了4类声功能区的距离范围,更加符合噪声传播特性;针对噪声污染特点,对于相关规范未涵盖的内容作了补充规定,使声环境管理更具针对性。区划结果表明,主城区1类区和3类区比例有所减小,2类区比例有所增加,全市范围内1类区比例仍为最高。 相似文献
992.
993.
中国西北地区地表植被覆盖特征的时空变化及影响因子分析 总被引:20,自引:4,他引:16
归一化的植被指数(NDVI)自然正交分解结果显示,自上世纪80年代初期至1994年前后,中国西北部区域地表植被覆盖呈增加的过程;1994~2000年,地表植被覆盖状况开始退化,植被退化强度空间分布不匀.TOVS云覆盖数据与地表特征时间变化的一致性,间接证明1994年之后西北部地区植被退化的事实.通过降水和NDVI的相关分析,划分出西北地区地表植被覆盖变化气候影响显著区域、气候与人为影响共同作用显著区域.并从气候和人为影响2个方面分析了造成西北部地区地表植被覆盖状况下降的原因.在降水和NDVI相关显著区域,气候干旱因素是造成1994年后植被覆盖退化的主要原因;而黄河等流域1994年后植被退化的区域,气候干旱和人为活动因素是造成植被覆盖退化的主要因素. 相似文献
994.
995.
海洋牧场建设是中国扩增海洋碳汇,实现碳中和战略目标的有效途径。碳汇具有明显的外部性,只有确定合理的补偿标准才能调动海洋牧场建设经营者积极性。以海洋牧场中藻类、贝类、鱼类、甲壳及其他类经济性碳汇资源为研究对象,利用最优化模型核算了碳汇资源生态价值的补偿标准。研究结果表明:藻类、贝类、鱼类、甲壳及其他类的生态补偿标准分别为134.94元/t、820.05元/t、782.39元/t、3764.16元/t,补偿标准存在种类间差异性。研究结果可为优化当前海洋牧场生态补偿政策提供理论参考。 相似文献
996.
Eugene Yee 《Environmental Fluid Mechanics》2009,9(4):389-407
The relationships between various normalized higher-order concentration moments in plumes dispersing in a built-up (urban)
environment have been investigated using a large concentration data set obtained in a boundary-layer water channel. This data
set consists of measurements of plume dispersion in a number of idealized obstacle arrays (e.g., cubical and non-cubical obstacles
in aligned and staggered arrangements with uniform, random and alternating heights). A remarkably robust feature of all the
concentration data was the observed collapse of the third- and fourth-order normalized concentration moments on the second-order
normalized concentration moment. The data are shown to collapse to a series of universal curves (independent of the geometry
of the obstacle array) and these curves were found to be identical to those observed previously for open-terrain plumes. The
results imply that the probability law of concentration in a plume dispersing in either a built-up environment or open terrain
has a universal form that can be specified by at most two independent parameters. The universal functions representing the
relationships between the normalized concentration moments were found to be well modeled (approximated) using a two-parameter
clipped-gamma probability law for the concentration. Finally, the clipped-gamma distribution was found to be in very good
conformance with the measured probability distribution of concentration for plumes dispersing in a built-up environment. 相似文献
997.
Rolf Turner 《Environmental and Ecological Statistics》2009,16(2):197-223
In this paper I demonstrate some of the techniques for the analysis of spatial point patterns that have become available due
to recent developments in point process modelling software. These developments permit convenient exploratory data analysis,
model fitting, and model assessment. Efficient model fitting, in particular, makes possible the testing of statistical hypotheses
of genuine interest, even when interaction between points is present, via Monte Carlo methods. The discussion of these techniques
is conducted jointly with and in the context of some preliminary analyses of a collection of data sets which are of considerable
interest in their own right. These data sets (which were kindly provided to me by the New Brunswick Department of Natural
Resources) consist of the complete records of wildfires which occurred in New Brunswick during the years 1987 through 2003.
In treating these data sets I deal with data-cleaning problems, methods of exploratory data analysis, means of detecting interaction,
fitting of statistical models, and residual analysis and diagnostics. In addition to demonstrating modelling techniques, I
include a discussion on the nature of statistical models for point patterns. This is given with a view to providing an understanding
of why, in particular, the Strauss model fails as a model for interpoint attraction and how it has been modified to overcome
this difficulty. All actual modelling of the New Brunswick fire data is done only with the intent of illustrating techniques.
No substantive conclusions are or can be drawn at this stage. Realistic modelling of these data sets would require incorporation
of covariate information which I do not so far have available.
相似文献
Rolf TurnerEmail: |
998.
Judy L. Meyer Michael J. Sale Patrick J. Mulholland N. LeRoy Poff 《Journal of the American Water Resources Association》1999,35(6):1373-1386
ABSTRACT: We review published analyses of the effects of climate change on goods and services provided by freshwater ecosystems in the United States. Climate-induced changes must be assessed in the context of massive anthropogenic changes in water quantity and quality resulting from altered patterns of land use, water withdrawal, and species invasions; these may dwarf or exacerbate climate-induced changes. Water to meet instream needs is competing with other uses of water, and that competition is likely to be increased by climate change. We review recent predictions of the impacts of climate change on aquatic ecosystems in eight regions of North America. Impacts include warmer temperatures that alter lake mixing regimes and availability of fish habitat; changed magnitude and seasonality of runoff regimes that alter nutrient loading and limit habitat availability at low flow; and loss of prairie pothole wetlands that reduces waterfowl populations. Many of the predicted changes in aquatic ecosystems are a consequence of climatic effects on terrestrial ecosystems; shifts in riparian vegetation and hydrology are particularly critical. We review models that could be used to explore potential effects of climate change on freshwater ecosystems; these include models of instream flow, bioenergetics models, nutrient spiraling models, and models relating riverine food webs to hydrologic regime. We discuss potential ecological risks, benefits, and costs of climate change and identify information needs and model improvements that are required to improve our ability to predict and identify climate change impacts and to evaluate management options. 相似文献
999.
以四川省二滩水电站淹没影响的盐边县城迁建前后环境状况变化为例 ,提出水库移民安置中应重视淹没实物环境功能的恢复。 相似文献
1000.