全文获取类型
收费全文 | 801篇 |
免费 | 156篇 |
国内免费 | 557篇 |
专业分类
安全科学 | 64篇 |
废物处理 | 167篇 |
环保管理 | 59篇 |
综合类 | 800篇 |
基础理论 | 201篇 |
污染及防治 | 195篇 |
评价与监测 | 21篇 |
社会与环境 | 4篇 |
灾害及防治 | 3篇 |
出版年
2024年 | 3篇 |
2023年 | 16篇 |
2022年 | 42篇 |
2021年 | 42篇 |
2020年 | 51篇 |
2019年 | 38篇 |
2018年 | 49篇 |
2017年 | 54篇 |
2016年 | 71篇 |
2015年 | 86篇 |
2014年 | 82篇 |
2013年 | 82篇 |
2012年 | 102篇 |
2011年 | 79篇 |
2010年 | 57篇 |
2009年 | 53篇 |
2008年 | 43篇 |
2007年 | 66篇 |
2006年 | 80篇 |
2005年 | 58篇 |
2004年 | 54篇 |
2003年 | 44篇 |
2002年 | 40篇 |
2001年 | 37篇 |
2000年 | 23篇 |
1999年 | 35篇 |
1998年 | 27篇 |
1997年 | 14篇 |
1996年 | 21篇 |
1995年 | 16篇 |
1994年 | 14篇 |
1993年 | 13篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 1篇 |
排序方式: 共有1514条查询结果,搜索用时 15 毫秒
991.
992.
Molecular Weight Changes and Polymeric Matrix Changes Correlated with the Formation of Degradation Products in Biodegraded Polyethylene 总被引:3,自引:0,他引:3
Ann-Christine Albertsson Bengt Erlandsson Minna Hakkarainen Sigbritt Karlsson 《Journal of Polymers and the Environment》1998,6(4):187-195
The molecular weight changes in abiotically and biotically degraded LDPE and LDPE modified with starch and/or prooxidant were compared with the formation of degradation products. The samples were thermooxidized for 6 days at 100°C to initiate degradation and then either inoculated with Arthobacter paraffineus or kept sterile. After 3.5 years homologous series of mono- and dicarboxylic acids and ketoacids were identified by GC-MS in abiotic samples, while complete disappearance of these acids was observed in biotic environments. The molecular weights of the biotically aged samples were slightly higher than the molecular weights of the corresponding abiotically aged samples, which is exemplified by the increase in
from 5200 g/mol for a sterile sample with the highest amount of prooxidant to 6000 g/mol for the corresponding biodegraded sample. The higher molecular weight in the biotic environment is explained by the assimilation of carboxylic acids and low molecular weight polyethylene chains by microorganisms. Assimilation of the low molecular weight products is further confirmed by the absence of carboxylic acids in the biotic samples. Fewer carbonyls and more double bonds were seen by FTIR in the biodegraded samples, which is in agreement with the biodegradation mechanism of polyethylene. 相似文献
993.
YANG Shao-xi FENG Yu-jie WAN Jia-feng LIN Qing-ying ZHU Wan-peng JIANG Zhan-peng 《环境科学学报(英文版)》2005,17(4):523-626
IntroductionPharmaceuticalindustrybecomesmoreandmoreimportantallovertheworld .InChina ,therearemorethan30 0plantsmanufacturingantibioticproduction .However,theplantsoftenproducealotofwastewatercontaininghighconcentrated,colortoxicorganiccompounds.Ifthepol… 相似文献
994.
995.
A new method of determining the cumulate concentration of hydroxyl radicals in the TiO2/Ti photoelectrocatalytic(PEC)oxidation system was established by o-phenanthroline-Fe(Ⅱ)(Fe(phen)32+) spectrophotometry and using anion 相似文献
996.
997.
998.
999.
Liu Ruiping Yang Yanling Li Guibai He Wenjie Han Hongda 《Frontiers of Environmental Science & Engineering in China》2007,1(2):240-245
This study focused on the adsorptive behaviors of humic acid onto freshly prepared hydrous MnO2(s) (δMnO2), and investigated the feasibility of employing δMnO2 for humic acid removal from drinking water. Effects of such parameters as molecular mass of humic acid, kinds of divalent
cations on adsorptive behaviors and possible mechanisms involved were investigated. This study indicated that humic acid with
higher molecular mass exhibited more tendency of adsorbing onto δMnO2 than that with lower molecular mass. Ca2+ facilitated more humic acid adsorption than Mg2+; UV-Vis spectra analysis indicated higher capabilities of Ca2+ coordinating with acidic functional groups of humic acid than that of Mg2+. Additionally, ζ potential characterization indicated that Ca2+ showed higher potential of increasing gz potential of δMnO2 than Mg2+. Ca2+ of 1.0 mmol/L increased ζ potential of δMnO2 from −37 mV (pH 7.9) to +7 mV (pH 7.2), while 1.0 mmol/L Mg2+ increased to lower value as −9 mV (pH 6.5), correspondingly. Fourier transform infrared (FTIR) spectra demonstrated the adsorption
of humic acid onto δMnO2, showing the important roles of-COO− functional groups and surface Mn-OH in the adsorption of humic acid onto δMnO2.
Translated from Acta Scientiae Circumstantiae, 2005, 25(3): 351–355 [译自: 环境科学学报] 相似文献
1000.
详细列出了分子表面积计算中所用的公式,并详尽地说明了所涉及各量的计算方法和应用注意的问题。在此基础上编写的SASA程序成功地应用于酚取代衍生物,所得表面积对于氯化酚能很好地预言其正辛醇/水分配系数,但对于带7种不同取代基的酚取代衍生物,除了分子表面积,还必须引入代基当量作描述变量,才能较好地预言其正辛醇/水分配系数,而且个别化合物应 被看作outlier,不能正确地被预言。 相似文献