全文获取类型
收费全文 | 16641篇 |
免费 | 4579篇 |
国内免费 | 27868篇 |
专业分类
安全科学 | 1534篇 |
废物处理 | 726篇 |
环保管理 | 1347篇 |
综合类 | 32443篇 |
基础理论 | 3245篇 |
污染及防治 | 7231篇 |
评价与监测 | 1596篇 |
社会与环境 | 355篇 |
灾害及防治 | 611篇 |
出版年
2024年 | 8篇 |
2023年 | 142篇 |
2022年 | 444篇 |
2021年 | 340篇 |
2020年 | 830篇 |
2019年 | 2067篇 |
2018年 | 2301篇 |
2017年 | 2373篇 |
2016年 | 2137篇 |
2015年 | 2569篇 |
2014年 | 3247篇 |
2013年 | 3603篇 |
2012年 | 3297篇 |
2011年 | 2949篇 |
2010年 | 2565篇 |
2009年 | 2573篇 |
2008年 | 2306篇 |
2007年 | 2228篇 |
2006年 | 1746篇 |
2005年 | 1293篇 |
2004年 | 1129篇 |
2003年 | 951篇 |
2002年 | 791篇 |
2001年 | 787篇 |
2000年 | 941篇 |
1999年 | 796篇 |
1998年 | 649篇 |
1997年 | 589篇 |
1996年 | 591篇 |
1995年 | 544篇 |
1994年 | 358篇 |
1993年 | 294篇 |
1992年 | 342篇 |
1991年 | 300篇 |
1990年 | 253篇 |
1989年 | 204篇 |
1988年 | 147篇 |
1987年 | 75篇 |
1986年 | 76篇 |
1985年 | 54篇 |
1984年 | 55篇 |
1983年 | 41篇 |
1982年 | 45篇 |
1981年 | 36篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1972年 | 5篇 |
1971年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
401.
水溶液中非离子氨百分比的计算 总被引:1,自引:0,他引:1
根据平衡常数与温度的关系,求出非离子氨百分比α(pH,t)的表达式,运用公式计算可以提高数据的准确性和批量计算的工作效率。 相似文献
402.
403.
浮选剂污染河段大型底栖无脊椎动物的群落特征及其对水质的评价 总被引:2,自引:0,他引:2
利用大型底栖动物的群落结构及其行为反应对有毒化合物——浮选剂污染河段水质进行评价,并提出了受浮选剂污染的污水生物系统评价标准.结果表明,主要污染物丁基磺药对涡虫(Dugesia gonocephala)的24h LC_51为78ppm.根据受污河段底栖动物群落的变化和涡虫在各断面河水中的行为反应,浮选剂污水生物系统可以划分成α-多污带,β-多污带,α-中污带,β-中污带和寡污带。并对所提出的浮选剂污水生物系统进行了讨论。 相似文献
404.
The waterquality of the downstream of Nanfei River and the northwest area of Lake Chao is evaluated from organic analysis aspect. PAHs such as fluoranthene, pyrene are detected in the waters collected from downstream river and river mouth. More phenolic compounds are found in the river water. Some halogenated hydrocarbons are present in the river and lake waters. A great many of aliphatic hydrocarbons and benzene hydrocarbons found in all the water samples are about one third of the total organics detected. The hydrophobic components are found to be present not only in water but also in suspended sediment. The ratio of the amount existing is 0.4 in sediment and 1 in particle-free water. The quantity of humic materials existing in lake water is larger than that in river water. The proportion of the humic materials in lake water to that in river water is 1.9 to 1. In the lake water, some natural substances, such as dimethyl disulfide, alpha-pinene, azulene, and 6- methyl -2-heptanone are observed. 相似文献
405.
A study for the photochemical behavior of some polyaromatic hydrocarbons (PAH), for example B(a )P, B( k )F and fluoranthene in coal smoke particles was performed by using indoor Teflon smog chamber.Experiments suggest that the photochemical reaction of PAH is first order reaction and kinetic rates of some PAH were obtained. It was shown that the reaction rate constant is proportional to light intensity and water vapor concentration. Temperature and PAH loading also have influence on PAH decay rate. A model for PAH loss has been set up on the basis of the results of our experiments and the simulating results of this model suggest that coal particle PAH half lives are of the order of a period of days in winter and a few hours in summer. Other factors which may have effect on the photochemical reaction of PAH have also been discussed. 相似文献
406.
This paper, based on the autonomy concept, continues to investigate hierarchical forms and spatial structure of ecosystems. The former can lead to limits for the selection of the component parts of an ecosystem and a distinction between its endogenous and exogenous variables; and the latter can be lead to a hypothesis of the space of an ecosystem: the space of an ecosystem = its habitat area + supporting area + impact area, and two characteristics of ecosystems, space-overlapping and the area of ecosystem space, have been further studied referring to human activities. 相似文献
407.
Alan B. Bolten Peter Feinsinger Herbert G. Baker Irene Baker 《Die Naturwissenschaften》1990,77(9):452-452
408.
409.