全文获取类型
收费全文 | 17482篇 |
免费 | 162篇 |
国内免费 | 184篇 |
专业分类
安全科学 | 442篇 |
废物处理 | 662篇 |
环保管理 | 1925篇 |
综合类 | 5464篇 |
基础理论 | 3599篇 |
环境理论 | 2篇 |
污染及防治 | 4142篇 |
评价与监测 | 888篇 |
社会与环境 | 633篇 |
灾害及防治 | 71篇 |
出版年
2018年 | 213篇 |
2017年 | 207篇 |
2016年 | 304篇 |
2015年 | 232篇 |
2014年 | 327篇 |
2013年 | 1159篇 |
2012年 | 383篇 |
2011年 | 526篇 |
2010年 | 502篇 |
2009年 | 563篇 |
2008年 | 586篇 |
2007年 | 607篇 |
2006年 | 533篇 |
2005年 | 469篇 |
2004年 | 508篇 |
2003年 | 462篇 |
2002年 | 443篇 |
2001年 | 618篇 |
2000年 | 416篇 |
1999年 | 287篇 |
1998年 | 208篇 |
1997年 | 211篇 |
1996年 | 198篇 |
1995年 | 235篇 |
1994年 | 249篇 |
1993年 | 208篇 |
1992年 | 226篇 |
1991年 | 233篇 |
1990年 | 256篇 |
1989年 | 229篇 |
1988年 | 182篇 |
1987年 | 181篇 |
1986年 | 181篇 |
1985年 | 181篇 |
1984年 | 199篇 |
1983年 | 187篇 |
1982年 | 195篇 |
1981年 | 207篇 |
1980年 | 169篇 |
1979年 | 181篇 |
1978年 | 147篇 |
1974年 | 148篇 |
1973年 | 146篇 |
1968年 | 156篇 |
1967年 | 184篇 |
1966年 | 156篇 |
1965年 | 149篇 |
1964年 | 152篇 |
1963年 | 141篇 |
1962年 | 139篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
995.
996.
Giant reed for selenium phytoremediation under changing climate 总被引:1,自引:0,他引:1
Hassan R. El-Ramady Neama Abdalla Tarek Alshaal Ahmed S. Elhenawy Mohamed S. Shams Salah E.-D. A. Faizy El-Sayed B. Belal Said A. Shehata Mohamed I. Ragab Megahed M. Amer Miklós Fári Attila Sztrik József Prokisch Dirk Selmar Ewald Schnug Elizabeth A. H. Pilon-Smits Samia M. El-Marsafawy Éva Domokos-Szabolcsy 《Environmental Chemistry Letters》2015,13(4):359-380
997.
998.
999.
Research on community characteristics of riparian herbs is an important scientific basis of riparian vegetation rehabilitation. This study aimed to investigate the species diversity and quantitative characteristics of riparian herbs in Liaohe River Conservation Area and its tributaries. Herbaceous communities were investigated by sample line method. Group average clustering analysis and detrended correspondence analysis (DCA) were used to find the major environmental factors affecting the distribution pattern of riparian herbaceous communities. The result showed altogether 154 herbaceous species, belonging to 40 families and 96 genera. The riparian herbaceous species diversity was found to be correlated to river slope, sinuosity and stream order, being lower in rivers of mountain area than in rivers of plain area, and higher in tributaries than in Liaohe River Conservation Area. Clustering analysis classified the herbaceous communities into 23 types, being dominated by hygrophytes including communities of Echinochloa crusgalli, Oenanthe javanica, Polygonum hydropiper, Murdannia keisak, Artemisia selengensis, Scirpus triqueter, Heleocharis soloniensis, Pycreus sanguinolentus, Cyperus fuscus, Phragmites australis, Polygonum amphibium, Carex diandra + Artemisia selengensis and Carex diandra + Rorippa islandica. Correlation analysis between DCA ordination axes and environmental factors showed that the altitude, river slope, sinuosity and stream level were the major environmental factors affecting the distribution pattern of herbaceous communities in the riparian zone of Liaohe River Conservation Area and its tributaries. The results of CCA showed that the contribution ratio of stream level was the highest, followed by altitude and slope, with sinuosity the last. The results suggested that riparian herbaceous characteristics are affected by the comprehensive force of altitude, river slope, sinuosity and stream order, and that Calamagrostis epigeios, Triarrhena sacchariflora and Phragmites australis are suitable species for riparian vegetation rehabilitation. 相似文献
1000.
A pot experiment was conducted to study the allelopathic effects of initial decomposing leaf litter of Cinnamomum camphora on growth and physiology of Impatiens balsamina. Three leaf litter treatments included 20, 40 and 80 g of C. camphora leaf litter mixed with 8 kg of soil, namely T1, T2, and T3, respectively. In order to test the effect of leaf litter addition on the permeability and ventilation of soil simultaneously, a parallel trial with steamed leaf litter was conducted with the three treatments of the leaf litter. The leaf litter was steamed for 2 d to remove the secondary metabolites as much as possible, dried, and then mixed with 8 kg of soil, namely Z1, Z2, and Z3, respectively. No leaf litter was added in control (CK). The growth parameters of I. balsamina were determined at the 20 d, 60 d, 100 d and 120 d after sowing and the main physiology indicators were determined at the 60 d. The results indicated that: (1) The ground surface diameter and height of I. balsamina were inhibited significantly at 60 d (P < 0.05). Photosynthetic pigments and gas exchange parameters of I. balsamina were inhibited significantly at 60 d, and the inhibition effect was stronger with increased amount of leaf litter addition. The chlorophyll content, Pn and Ls decreased significantly with increased amount of leaf litter (P < 0.05). The activity of superoxide dismutase (SOD) and peroxidase (POD) in leaves of I. balsamina decreased with the increase of leaf litter addition. The content of MDA in treatments T1, T2 and T3 were all higher than that in CK, which indicated that I. balsamina suffered oxidative damage in a certain degree. The content of free proline (Pro) and soluble sugar (SS) in leaves of I. balsamina decreased significantly with the increase of the leaf litter (P < 0.05), while the content of soluble protein (SP) increased. (2) In the parallel trial, 60 d after sowing, no obvious difference was observed between CK and any steamed leaf litter treatment in terms of the morphological and physiological features stated above (P > 0.05). It indicated that the soil physical properties were not greatly influenced by leaf litter addition in the dose interval designed, or that the release of secondary metabolites from decomposing leaf litter was probably a better reason to explain the inhibition of leaf litter treatment to I. balsamina growth. (3)The compound effect (CE) of leaf litter decomposition on I. balsamina was enhanced with increase of the leaf litter, to 0.169, 0.354, and 0.497, respectively, in treatments of T1, T2 and T3. The study indicated that initial decomposition of C. camphora leaf litter in soil reduces the content of photosynthetic pigments, inhibits photosynthetic capacity and resistance physiology of I. balsamina, weakens its adaptability to the environment, and restrains growth of the plant. © 2015, Science Press. All rights reserved. 相似文献