全文获取类型
收费全文 | 4379篇 |
免费 | 382篇 |
国内免费 | 780篇 |
专业分类
安全科学 | 601篇 |
废物处理 | 38篇 |
环保管理 | 606篇 |
综合类 | 2401篇 |
基础理论 | 720篇 |
污染及防治 | 182篇 |
评价与监测 | 375篇 |
社会与环境 | 403篇 |
灾害及防治 | 215篇 |
出版年
2024年 | 17篇 |
2023年 | 83篇 |
2022年 | 126篇 |
2021年 | 166篇 |
2020年 | 134篇 |
2019年 | 141篇 |
2018年 | 130篇 |
2017年 | 189篇 |
2016年 | 225篇 |
2015年 | 237篇 |
2014年 | 235篇 |
2013年 | 322篇 |
2012年 | 410篇 |
2011年 | 412篇 |
2010年 | 315篇 |
2009年 | 280篇 |
2008年 | 231篇 |
2007年 | 283篇 |
2006年 | 287篇 |
2005年 | 227篇 |
2004年 | 153篇 |
2003年 | 143篇 |
2002年 | 118篇 |
2001年 | 98篇 |
2000年 | 108篇 |
1999年 | 86篇 |
1998年 | 54篇 |
1997年 | 50篇 |
1996年 | 44篇 |
1995年 | 37篇 |
1994年 | 45篇 |
1993年 | 29篇 |
1992年 | 21篇 |
1991年 | 26篇 |
1990年 | 16篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1974年 | 2篇 |
1972年 | 3篇 |
1971年 | 2篇 |
排序方式: 共有5541条查询结果,搜索用时 836 毫秒
421.
差异性区域网格化环境管理是在环境状况存在明显分异区域进行环境管理的有效的方式。依托网格化管理在资源整合和信息共事方面的优势.探讨在环境状况差异明显区域构建网格化管理体系的目标、步骤与管理思路。以上海市宝山区的实践为例.根据区内环境现状差异明显的特征。将全区划分为150个网格.从中选取环境矛盾较为突出的网格.开展区域环境综合整治与环境建设.逐年逐块提升区域网格环境状况.实现区域环境网格等级的提升.初步达成区域生态、生产、生活的协调。实践表明.差异性区域网格化管理是建设环境友好型社会的一种有效的环境管理手段。 相似文献
422.
用于评价水污染的生物指数 总被引:13,自引:0,他引:13
对各国学者所建立的应用较广泛的生物指数作了综述 ,通过分析各种生物指数的优点与缺陷 ,指出了目前建立生物指数方法上的不足 ,并提出了建立生物指数应该采用的更合理的方法。 相似文献
423.
This paper aims to identify the main driving force for changes of total primary energy consumption in Beijing during the period of 1981-2005. Sectoral energy use was investigated when regional economic structure changed significantly. The changes of total primary energy consumption in Beijing are decomposed into production effects, structural effects and intensity effects using the additive version of the logarithmic mean Divisia index (LMDI) method. Aggregate decomposition analysis showed that the major contributor of total effect was made by the production effect followed by the intensity effect, and the structural effect was relatively insignificant. The total and production effects were all positive. In contrast, the structural effect and intensity effect were all negative. Sectoral decomposition investigation indicated that the most effective way to slow down the growth rate of total primary energy consumption (TPEC) was to reduce the production of the energy-intensive industrial sectors and improving industrial energy intensity. The results show that in this period, Beijing's economy has undergone a transformation from an industrial to a service economy. However, the structures of sectoral energy use have not been changed yet, and energy demand should be increasing until the energy-intensive industrial production to be reduced and energy intensity of the region reaches a peak. As sequence energy consumption data of sub-sectors are not available, only the fundamental three sectors are considered: agriculture, industry and service. However, further decomposition into secondary and tertiary sectors is definitely needed for detailed investigations. 相似文献
424.
植被是陆地表面主要的覆盖物,也是许多地球系统过程的重要变量。人类活动对植被的影响在区域尺度上是显著的。以重庆市为例,使用滑动平均和SG滤波对SPOT/VGT NDVI时间序列数据进行了平滑处理,结合GDP和人口栅格化数据,从时间序列和空间相关场两个方面分析了植被与人类活动因子之间的时空相关性。结果表明,从1998到2005年,植被的分布和生长状况并没有随GDP和人口的持续增加而增加。在时间序列上,植被覆盖与GDP和人口之间总体上呈显著的负相关关系;在空间上,这种相关关系表现出了较强的异质性。空间相关场表明:较强的负相关主要发生在相对发达的主城区周围,反映了快速的经济发展和城市化使得植被面积和生产力降低;然而在偏远的山区,由于经济落后同时植被覆盖较少,出现了正相关。 相似文献
425.
中国县域资源组合结构的分类研究 总被引:7,自引:0,他引:7
按区域经济的发展,遵循资源分布的地域分异规律,论述了中国县域资源的地域组合结构的分类问题。首先对采用多因素综合作用、自然资源与经济资源兼容组合、资源优势、资源系统良性循环等原则进行了必要性的论证;在此基础上重点对其分类方法进行了具体说明,其主要步骤是在确定10种主要的县域资源,建立相关在指标体系的前提下,鉴于威弗组合指数对于划分县域资源组合结构类型的可行性,运用改造过的,角立县域资源地域组合结构类型的划分程序与计算方法。最后,按此分类法,把我国县域资源地域组合结构类型划分为自然资源型、自然资源主导型、自然资源与经济资源混合型、经济资源主导型、经济资源密集类等5个一级类型及其下属的8个二级类型。 相似文献
426.
427.
Abstract: Habitat fragmentation is a severe threat to tropical biotas, but its long‐term effects are poorly understood. We evaluated longer‐term changes in the abundance of larger (>1 kg) mammals in fragmented and intact rainforest and in riparian “corridors” in tropical Queensland, with data from 190 spotlighting surveys conducted in 1986–1987 and 2006–2007. In 1986–1987 when most fragments were already 20–50 years old, mammal assemblages differed markedly between fragmented and intact forest. Most vulnerable were lemuroid ringtail possums (Hemibelideus lemuroides), followed by Lumholtz's tree‐kangaroos (Dendrolagus lumholtzi) and Herbert River ringtail possums (Pseudocheirus herbertensis). Further changes were evident 20 years later. Mammal species richness fell significantly in fragments, and the abundances of 4 species, coppery brushtail possums (Trichosurus vulpecula johnstoni), green ringtail possums (Pseudochirops archeri), red‐legged pademelons (Thylogale stigmatica), and tree‐kangaroos, declined significantly. The most surprising finding was that the lemuroid ringtail, a strict rainforest specialist, apparently recolonized one fragment, despite a 99.98% decrease in abundance in fragments and corridors. A combination of factors, including long‐term fragmentation effects, shifts in the surrounding matrix vegetation, and recurring cyclone disturbances, appear to underlie these dynamic changes in mammal assemblages. 相似文献
428.
《环境科学学报(英文版)》2023,35(4):483-493
When exposed to different relative humidities (RHs), the optical properties of atmospheric aerosols will change because of changes in the aerosol particle size and complex refractive index (RI), which will affect haze formation and global climate change. The potential contributions of ultrafine particles to the atmospheric optical characteristics and to haze spreading cannot be ignored because of their high particle number concentrations and strong diffusibility; measurement of the optical properties of wet ultrafine particles is thus highly important for environmental assessment. Therefore, a surface plasmon resonance microscopy with azimuthal rotation illumination (SPRM-ARI) system is designed to determine the RIs of single particle aerosols with diameters of less than 100 nm in the hygroscopic growth process. Measurements are taken using mixed single particles with different mass ratios. The RIs of mixed single aerosols at different RHs are retrieved by measuring the scattering light intensity using the SPRM-ARI system and almost all the RIs of the bicomponent particles with different mass ratios decrease with increasing water content under high RH conditions. Finally, for each of the bicomponent particles, the maximum standard deviations for the retrieved RI values are only , and , corresponding to the NaCl and NaNO3 bicomponent particles with a 3:1 mass ratio at 76.0% RH, the NaCl and glucose particles with a 1:3 mass ratio at 89.0% RH, and the NaCl and OA particles with a 1:1 mass ratio at 78.0% RH, respectively; these results indicate that the high-sensitivity SPRM-ARI system can measure the RI effectively and accurately. 相似文献
429.
430.