全文获取类型
收费全文 | 2282篇 |
免费 | 106篇 |
国内免费 | 846篇 |
专业分类
安全科学 | 173篇 |
废物处理 | 146篇 |
环保管理 | 162篇 |
综合类 | 1278篇 |
基础理论 | 392篇 |
污染及防治 | 772篇 |
评价与监测 | 82篇 |
社会与环境 | 67篇 |
灾害及防治 | 162篇 |
出版年
2024年 | 1篇 |
2023年 | 44篇 |
2022年 | 120篇 |
2021年 | 108篇 |
2020年 | 66篇 |
2019年 | 75篇 |
2018年 | 81篇 |
2017年 | 116篇 |
2016年 | 146篇 |
2015年 | 173篇 |
2014年 | 167篇 |
2013年 | 235篇 |
2012年 | 188篇 |
2011年 | 198篇 |
2010年 | 156篇 |
2009年 | 130篇 |
2008年 | 157篇 |
2007年 | 124篇 |
2006年 | 105篇 |
2005年 | 76篇 |
2004年 | 64篇 |
2003年 | 75篇 |
2002年 | 61篇 |
2001年 | 58篇 |
2000年 | 60篇 |
1999年 | 83篇 |
1998年 | 61篇 |
1997年 | 57篇 |
1996年 | 50篇 |
1995年 | 49篇 |
1994年 | 28篇 |
1993年 | 38篇 |
1992年 | 31篇 |
1991年 | 24篇 |
1990年 | 14篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1984年 | 3篇 |
1981年 | 2篇 |
1958年 | 1篇 |
排序方式: 共有3234条查询结果,搜索用时 15 毫秒
851.
峨嵋山冷杉衰亡与酸性降水关系的初步研究 总被引:3,自引:0,他引:3
本文报道了峨嵋山高海拔地区冷杉衰亡与酸性降水关系的调查和研究,内容包括酸性降水和气态污染物状况的观察,冷杉枝叶生长状况和针叶解剖,树干解剖和根系观察,冷杉冠层对酸性降水的反应及酸性降水在生态系统中的变化,土壤和冷杉的元素分析等方面,并就酸性降水对冷杉衰亡的影响进行了初步评价结果指出,峨嵋山高海拔地区的酸性降水污染严重,雨水的平均pH值为1.37,酸雨频率达85.1:雾水的pH值为1.62,酸雾频率达100 有可能对冷杉产生直接和间接影响。 相似文献
852.
The formation and aging mechanism of secondary organic aerosol (SOA) and its influencing factors have attracted increasing attention in recent years because of their effects on climate change, atmospheric quality and human health. However, there are still large errors between air quality model simulation results and field observations. The currently undetected components during the formation and aging of SOA due to the limitation of current monitoring techniques and the interactions among multiple SOA formation influencing factors might be the main reasons for the differences. In this paper, we present a detailed review of the complex dynamic physical and chemical processes and the corresponding influencing factors involved in SOA formation and aging. And all these results were mainly based the studies of photochemical smog chamber simulation. Although the properties of precursor volatile organic compounds (VOCs), oxidants (such as OH radicals), and atmospheric environmental factors (such as NOx, SO2, NH3, light intensity, temperature, humidity and seed aerosols) jointly influence the products and yield of SOA, the nucleation and vapor pressure of these products were found to be the most fundamental aspects when interpreting the dynamics of the SOA formation and aging process. The development of techniques for measuring intermediate species in SOA generation processes and the study of SOA generation and aging mechanism in complex systems should be important topics of future SOA research. 相似文献
853.
介绍了一种将氯乙酰胺和牛磺酸反应,一步法合成N-(2-乙酰胺基)-2-氨基乙烷磺酸的新方法,所得产物为白色结晶 ,产率为45%-55%,以此ACES配制的BCYEα培养基与进口的ACES配制的增减基相比,两者在军团菌培养上效果十分接近。 相似文献
854.
杭州煤场煤尘环境影响预测分析 总被引:1,自引:0,他引:1
介绍杭州煤场煤炭堆放,装卸及运输过程过程中 煤尘产生量的估算法,估算煤尘的分粒瞬时源强,单源及多源叠加下风向煤尘预测浓度公式及预测为同类型煤场大气环境影响评价提供参考。 相似文献
855.
856.
Particles from ambient air and combustion sources including vehicle emission, coal combustion and biomass burning were collected and chemically pretreated with the purpose of obtaining isolated BC (black carbon) samples. TEM (transmission electron microscopy) results indicate that BC from combustion sources shows various patterns, and airborne BC appears spherical and about 50 nm in diameter with a homogeneous surface and turbostratic structure. The BET (Barrett–Emmett–Teller) results suggest that the surface areas of these BC particles fall in the range of 3–23 m2/g, with a total pore volume of 0.03–0.05 cm3/g and a mean pore diameter of 7–53 nm. The nitrogen adsorption–desorption isotherms are indicative of the accumulation mode and uniform pore size. O2-TPO (temperature programmed oxidation) profiles suggest that the airborne BC oxidation could be classified as the oxidation of amorphous carbon, which falls in the range of 406–490°C with peaks at 418, 423 and 475°C, respectively. Generally, the BC characteristics and source analysis suggest that airborne BC most likely comes from diesel vehicle emission at this site. 相似文献
857.
858.
介绍了剩磁法原理和剩磁检测依据标准,使用雷电流发生器和高斯计对磁钢棒的剩磁状况进行了初步的试验研究。 相似文献
859.
860.
阐述了炼化企业变更管理系统的6个环节:识别潜在的变更、评估可能的影响、变更审批、变更实施、变更验收和变更追踪,并提出了确保变更质量的保障措施。 相似文献