全文获取类型
收费全文 | 4737篇 |
免费 | 389篇 |
国内免费 | 1691篇 |
专业分类
安全科学 | 480篇 |
废物处理 | 242篇 |
环保管理 | 358篇 |
综合类 | 3015篇 |
基础理论 | 794篇 |
环境理论 | 1篇 |
污染及防治 | 1229篇 |
评价与监测 | 263篇 |
社会与环境 | 215篇 |
灾害及防治 | 220篇 |
出版年
2024年 | 28篇 |
2023年 | 132篇 |
2022年 | 346篇 |
2021年 | 277篇 |
2020年 | 263篇 |
2019年 | 230篇 |
2018年 | 229篇 |
2017年 | 242篇 |
2016年 | 261篇 |
2015年 | 283篇 |
2014年 | 321篇 |
2013年 | 460篇 |
2012年 | 414篇 |
2011年 | 451篇 |
2010年 | 329篇 |
2009年 | 312篇 |
2008年 | 334篇 |
2007年 | 284篇 |
2006年 | 239篇 |
2005年 | 186篇 |
2004年 | 119篇 |
2003年 | 141篇 |
2002年 | 138篇 |
2001年 | 97篇 |
2000年 | 109篇 |
1999年 | 94篇 |
1998年 | 91篇 |
1997年 | 70篇 |
1996年 | 84篇 |
1995年 | 58篇 |
1994年 | 26篇 |
1993年 | 42篇 |
1992年 | 35篇 |
1991年 | 26篇 |
1990年 | 16篇 |
1989年 | 9篇 |
1988年 | 13篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1984年 | 4篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1975年 | 1篇 |
1958年 | 1篇 |
1956年 | 2篇 |
排序方式: 共有6817条查询结果,搜索用时 281 毫秒
51.
52.
随着旅游和假日经济的日益升温,旅游资源的环境保护就显得更为迫切。本文基于旅游业的可持续发展要求,提出了有效保护旅游资源环境的几点对策 相似文献
53.
54.
采用水解酸化厌氧好氧混凝吸附工艺处理洁霉素生产丁提高浓度有机废水,工程实践表明,CODCr和BOD5去除率在99%以上,所排废水各项指标达到国家排放标准。 相似文献
55.
56.
57.
A Simulation of Temporal and Spatial Variations in Carbon at Landscape Level: A Case Study for Lake Abitibi Model Forest in Ontario,Canada 总被引:2,自引:0,他引:2
Xiaolu Zhou Changhui Peng Qing-Lai Dang Jiaxin Chen Sue Parton 《Mitigation and Adaptation Strategies for Global Change》2007,12(4):525-543
Using a case study of the Lake Abitibi Model Forest (LAMF), this study aims to assess the temporal and spatial variability
in carbon storage during 1990–2000, and to present a comprehensive estimation of the carbon budget for LAMF's ecosystems.
As well, it provided the information needed by local forest managers to develop ecological and carbon-based indicators and
monitor the sustainability of forest ecosystems. Temporal and spatial carbon dynamics were simulated at the landscape level
using ecosystem model TRIPLEX1.0 and Geographical Information System (GIS). The simulated net primary productivity (NPP) and
carbon storage in forest biomass and soil were compared with field data and results from other studies for Canada's boreal
forests. The results show that simulated NPP ranged from 3.26 to 3.34 tC ha−1 yr−1 in the 1990s and was consistent with the range measured during the Boreal Ecosystem-Atmosphere Studies (BOREAS) in central
Canada. Modeled NPP was also compared with the estimation from remote sensing data. The density of total above-and belowground
biomass was 125.3, 111.8, and 106.5 tC ha−1 for black spruce, trembling aspen, and jack pine in the LAMF ecosystem, respectively. The total carbon density of forested
land was estimated at 154.4 tC ha−1 with the proportion of 4:6 for total biomass and soil. The analysis of net carbon balance of ecosystem suggested that the
LAMF forest ecosystem was acting as a carbon sink with an allowable harvest in the 1990s. 相似文献
58.
Given the key role of biogenic volatile organic compounds(VOCs) to tropospheric chemistry and regional air quality, it is important to generate accurateVOCs emission inventories. However, only a less fraction of plant species, in temperate grassland of Inner Mongolia, has been characterized by quantitative measurements. A taxonomic methodology, which assigns VOCs measurements to unmeasured species, is an applicable and inexpensive alternation for extensive VOCs emission survey, although data are needed for additional plant families and genera to further validate the taxonomic approach in grassland vegetation. In this experiment, VOCs emission rates of 178 plant species were measured with a portable photoionization detector( PID). The results showed the most of genera and some families have consistent feature of their VOCs emission, especially for isoprene, and provide the basic premise of taxonomic methodology to develop VOCs emission inventories for temperate grassland. Then, the taxonomic methodology was introduced into assigning emission rate to other 96 species, which no measured emission rates available here. A systematical emission inventory of temperate grassland vegetation in Inner Mongolia was provided and further evidence that taxonomy relationship can serve as a useful guide for generalizing the emissions behavior of many, but not all, plant families and genera to grassland vegetation. 相似文献
59.
一个耐受镉毒害的拟南芥突变体的筛选 总被引:3,自引:0,他引:3
从甲基磺酸乙酯(EMS)诱变获得的拟南芥M2代群体(Columbia型)中筛选获得一个耐受镉Cd2 毒害能力显著增强的拟南芥突变体(命名为cdr1-1).遗传分析表明,该突变性状为隐性单基因突变,与野生型相比,cdr1-1突变体在不同发育时期均能耐受Cd2 毒害,且其对Cd2 的积累能力也显著高于野生型.此外,还发现cdr1-1突变体体内的还原型谷胱甘肽(GSH)水平显著高于野生型,用GSH合成抑制剂丁硫氨酸亚矾胺处理cdr1-1突变体,导致其耐受Cd2 毒害能力显著下降,几乎接近野生型水平,表明cdr1-1突变体对Cd2 的耐受性至少部分依赖于GSH介导的途径. 相似文献
60.