全文获取类型
收费全文 | 29355篇 |
免费 | 3047篇 |
国内免费 | 8319篇 |
专业分类
安全科学 | 3841篇 |
废物处理 | 509篇 |
环保管理 | 4867篇 |
综合类 | 19631篇 |
基础理论 | 5026篇 |
环境理论 | 55篇 |
污染及防治 | 2101篇 |
评价与监测 | 1861篇 |
社会与环境 | 2160篇 |
灾害及防治 | 670篇 |
出版年
2024年 | 126篇 |
2023年 | 752篇 |
2022年 | 1120篇 |
2021年 | 1323篇 |
2020年 | 1288篇 |
2019年 | 1290篇 |
2018年 | 1110篇 |
2017年 | 1443篇 |
2016年 | 1611篇 |
2015年 | 1681篇 |
2014年 | 1602篇 |
2013年 | 2468篇 |
2012年 | 2537篇 |
2011年 | 2613篇 |
2010年 | 1967篇 |
2009年 | 2000篇 |
2008年 | 1545篇 |
2007年 | 2088篇 |
2006年 | 2033篇 |
2005年 | 1645篇 |
2004年 | 1422篇 |
2003年 | 1238篇 |
2002年 | 944篇 |
2001年 | 830篇 |
2000年 | 810篇 |
1999年 | 592篇 |
1998年 | 434篇 |
1997年 | 399篇 |
1996年 | 306篇 |
1995年 | 313篇 |
1994年 | 239篇 |
1993年 | 224篇 |
1992年 | 153篇 |
1991年 | 93篇 |
1990年 | 73篇 |
1989年 | 54篇 |
1988年 | 51篇 |
1987年 | 17篇 |
1986年 | 29篇 |
1985年 | 15篇 |
1984年 | 17篇 |
1983年 | 17篇 |
1982年 | 27篇 |
1981年 | 35篇 |
1980年 | 23篇 |
1979年 | 19篇 |
1978年 | 15篇 |
1977年 | 16篇 |
1973年 | 18篇 |
1971年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
982.
根据社会组织中客观存在的层级结构,描述了环境监测站的层级构成及其基本职能, 认识和合理利用层级管理制度有利于内设机构的设置、合理地配置其职能并确保机构高效 运行。 相似文献
983.
城市光污染侵害案件法律适用问题的探讨 总被引:1,自引:0,他引:1
在城市光污染侵害案件日益增多的同时,我国光污染侵害的法律救济手段和救济结果却不尽人意。虽然我国在宪法、环境保护法等法律、法规及民法中都有处理光污染侵害案件的法律依据,但由于缺少直接的规定,使环境保护法律体系存在太大的缺陷。因此,亟待制定有关的标准和修改相关的法律,从而更好地防治光污染,维护受害人的合法权益。 相似文献
984.
本文结合博兴县污水处理厂实行BOT融资模式,有的放矢的探讨了环保基础设施建 设引入BOT机制的积极作用与风险。 相似文献
985.
David Fowler Jennifer B. A. Muller Lucy J. Sheppard 《Water, Air, & Soil Pollution: Focus》2004,4(6):3-8
This paper provides the background to this special issue, outlining the extent to which the global atmospheric nitrogen cycle has been modified by human activity and outlining the range of effects. The global total emissions of reduced and oxidized nitrogen, amount to 124 Tg N, and exceed those from natural sources (34 Tg N) by almost a factor of four showing the extent to which anthropogenic activity has taken over the global N cycle. Of the 124 Tg N, 70 Tg N is emitted in the oxidized form, largely as NO and 70% of which results directly from anthropogenic activity. The remaining 54 Tg N is emitted as NH3, (66% anthropogenic). The enhanced nitrogen emissions are associated with a range of local, regional and global issues including, acidification, eutrophication, climate change, human health and tropospheric O3. The paper also places the Global Nitrogen Enrichment (GaNE) research programme in the UK in a wider perspective. 相似文献
986.
Nugraha E. Suyatma Alain Copinet Lan Tighzert Veronique Coma 《Journal of Polymers and the Environment》2004,12(1):1-6
Biodegradable film blends of chitosan with poly(lactic acid) (PLA) were prepared by solution mixing and film casting. The main goal of these blends is to improve the water vapor barrier of chitosan by blending it with a hydrophobic biodegradable polymer from renewable resources. Mechanical properties of obtained films were assessed by tensile test. Thermal properties, water barrier properties, and water sensitivity were studied by differential scanning calorimeter analysis, water vapor permeability measurements, and surface-angle contact tests, respectively. The incorporation of PLA to chitosan improved the water barrier properties and decreased the water sensitivity of chitosan film. However, the tensile strength and elastic modulus of chitosan decreased with the addition of PLA. Mechanical and thermal properties revealed that chitosan and PLA blends are incompatible, consistent with the results of Fourier transform infrared (FTIR) analysis that showed the absence of specific interaction between chitosan and PLA. 相似文献
987.
Gregory M. Glenn Artur K. Klamczynski Bor-Sen Chiou Delilah Wood William J. Orts Syed H. Imam 《Journal of Polymers and the Environment》2004,12(3):189-196
Starch aquagel-based lightweight concrete has properties similar to those of other lightweight concrete products. However, starch aquagels are unstable in the strongly alkaline conditions typical of Portland Cement-based concrete and may interfere with the setting process. The effect of alkali treatments on the physical, mechanical, and functional properties of starch aquagels and aquagels from starch/polymer blends was investigated. Starch was blended at 100–115°C in a twin-screw extruder with five different polymers to determine whether the blends improved alkaline resistance. Polymer blends containing 5%, 15%, and 30% of the polymer hydrated and formed aquagels when equilibrated in water for 24 h. However, equilibrium moisture content was lower for the blends compared to the starch control. Aquagels equilibrated in 0.15 N NaOH swelled, lost compressive strength and had greater than 90% moisture. The blend of starch and 30% PVOH absorbed less moisture and was more resistant to alkaline dissolution in 1 N NaOH than the other blends tested making it a more suitable material for aquagel-based concrete. The moisture content of starch-based aquagels and mixing time were critical factors in determining setting times. The size of aquagel blends had a minor effect on density and compressive strength. 相似文献
988.
989.
以最大信息熵原理为理论基础的熵法估参方法,是一种具有严格物理和数学意义的新型参数估计方法,本文针对珠江广州河段主要污染物含量长年监测数据,对比熵法与传统方法矩法对四参数Г分布的估参结果,并以频率绝对离盖和最小为准则进行判定,结果表明,熵法估参结果与矩法总体上相当接近,且大部分样本的熵法估计参数优于矩法,在环境监测数据频率分析中具有实用性和推广价值。 相似文献
990.