全文获取类型
收费全文 | 2137篇 |
免费 | 352篇 |
国内免费 | 1182篇 |
专业分类
安全科学 | 296篇 |
废物处理 | 73篇 |
环保管理 | 140篇 |
综合类 | 2110篇 |
基础理论 | 327篇 |
污染及防治 | 323篇 |
评价与监测 | 310篇 |
社会与环境 | 36篇 |
灾害及防治 | 56篇 |
出版年
2024年 | 23篇 |
2023年 | 67篇 |
2022年 | 151篇 |
2021年 | 159篇 |
2020年 | 167篇 |
2019年 | 157篇 |
2018年 | 157篇 |
2017年 | 153篇 |
2016年 | 166篇 |
2015年 | 199篇 |
2014年 | 190篇 |
2013年 | 251篇 |
2012年 | 221篇 |
2011年 | 191篇 |
2010年 | 140篇 |
2009年 | 158篇 |
2008年 | 115篇 |
2007年 | 186篇 |
2006年 | 132篇 |
2005年 | 102篇 |
2004年 | 76篇 |
2003年 | 66篇 |
2002年 | 75篇 |
2001年 | 67篇 |
2000年 | 65篇 |
1999年 | 29篇 |
1998年 | 43篇 |
1997年 | 30篇 |
1996年 | 32篇 |
1995年 | 16篇 |
1994年 | 9篇 |
1993年 | 18篇 |
1992年 | 13篇 |
1991年 | 10篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有3671条查询结果,搜索用时 390 毫秒
751.
PAN Yong-zhan YU Guang-ming WANG Xiao-dong . Henan University of Science Technology Luoyang China . Qingdao Technological University Qingdao China . Pingdingshan Coal Group Pingdingshan China 《地球与环境》2005,33(Z1):130-132
<正>Based on the noncontinuity of rock mass, views it as a system made of blocks that are divided by dissconti-nuties. Take the relative displacement of blocks as order parameter and establish its main equation using the micro-cosmic disposal method of synergetics. Then solve this equation and get its solution of nonstationary state. Narrate the characteristic of change and interrelated factors of blocks' displacement through the analysis of nonstationary state of main equation. 相似文献
752.
Matthew R. Redding Alan Skerman John Ritchie Kenneth D. Casey 《Agriculture, ecosystems & environment》2007,120(2-4):166-178
Nutrient mass balances have been used to assess a variety of land resource scenarios, at various scales. They are widely used as a simple basis for policy, planning, and regulatory decisions but it is not clear how accurately they reflect reality. This study provides a critique of broad-scale nutrient mass balances, with particular application to the fertiliser use of beef lot-feeding manure in Queensland.Mass balances completed at the district and farm scale were found to misrepresent actual manure management behaviour and potentially the risk of nutrient contamination of water resources. The difficulties of handling stockpile manure and concerns about soil compaction mean that manure is spread thickly over a few paddocks at a time and not evenly across a whole farm. Consequently, higher nutrient loads were applied to a single paddock less frequently than annually. This resulted in years with excess nitrogen, phosphorus, and potassium remaining in the soil profile. This conclusion was supported by evidence of significant nutrient movement in several of the soil profiles studied.Spreading manure is profitable, but maximum returns can be associated with increased risk of nutrient leaching relative to conventional inorganic fertiliser practices. Bio-economic simulations found this increased risk where manure was applied to supply crop nitrogen requirements (the practice of the case study farms, 200–5000 head lot-feeders).Thus, the use of broad-scale mass balances can be misleading because paddock management is spatially heterogeneous and this leads to increased local potential for nutrient loss. In response to the effect of spatial heterogeneity policy makers who intend to use mass balance techniques to estimate potential for nutrient contamination should apply these techniques conservatively. 相似文献
753.
A. C. C. van Oppen E. J. Breslau-Siderius Ph. Stoutenbeek A. J. Pull Ter Gunne J. M. W. M. Merkus 《黑龙江环境通报》1991,11(12):915-920
Tuberous sclerosis is a single gene autosomal-dominant disorder, characterized by multiple hamartoma formation. It shows a wide variability of expression. Prenatal diagnosis by means of a DNA or biochemical marker is not yet possible. Ultrasound offers the only way to detect possible antenatal hamartoma formation, which is most commonly found in the central nervous system, the renal system, and the heart. We report a case of fetal involvement that appears unique because of the unusual location of a tumour in the neck of the fetus. 相似文献
754.
755.
756.
IntroductionThesolid/fluidtwophaseflowsareoftenencounteredinmanyenvironmental,chemicalandhydraulicengineering,suchassedimenttransportationinrivers,wastewaterflowwithsolidparticlesandsoon.Recently,considerableeffortsregardingnumericalpredictionshaveb… 相似文献
757.
大气细颗粒物的透射电子显微镜研究 总被引:3,自引:1,他引:3
利用透射电子显微镜(TEM)对北京市区和背景点的细颗粒物(PM2.5)的形貌特征和集聚状态进行分析,结合颗粒物能谱(EDX)和选区电子衍射(SAED)特征,将北京市大气细颗粒物分为烟尘集合体、飞灰、矿物颗粒、硫酸盐和有机颗粒等5种单颗粒类型,并讨论了它们的来源.TEM分析表明,北京市区和背景点大气细颗粒物中不同类型的单颗粒所占比例不同,表明市区和背景点细颗粒物的污染物源有所不同.研究还表明,不同类型的细颗粒之间常常发生聚集. 相似文献
758.
759.
760.