全文获取类型
收费全文 | 8796篇 |
免费 | 711篇 |
国内免费 | 3018篇 |
专业分类
安全科学 | 871篇 |
废物处理 | 434篇 |
环保管理 | 785篇 |
综合类 | 5523篇 |
基础理论 | 1371篇 |
污染及防治 | 2223篇 |
评价与监测 | 467篇 |
社会与环境 | 426篇 |
灾害及防治 | 425篇 |
出版年
2024年 | 31篇 |
2023年 | 139篇 |
2022年 | 457篇 |
2021年 | 375篇 |
2020年 | 392篇 |
2019年 | 327篇 |
2018年 | 337篇 |
2017年 | 445篇 |
2016年 | 445篇 |
2015年 | 503篇 |
2014年 | 624篇 |
2013年 | 862篇 |
2012年 | 764篇 |
2011年 | 890篇 |
2010年 | 669篇 |
2009年 | 665篇 |
2008年 | 683篇 |
2007年 | 635篇 |
2006年 | 584篇 |
2005年 | 391篇 |
2004年 | 293篇 |
2003年 | 303篇 |
2002年 | 254篇 |
2001年 | 211篇 |
2000年 | 226篇 |
1999年 | 163篇 |
1998年 | 140篇 |
1997年 | 145篇 |
1996年 | 112篇 |
1995年 | 107篇 |
1994年 | 81篇 |
1993年 | 76篇 |
1992年 | 73篇 |
1991年 | 47篇 |
1990年 | 29篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
661.
A hydroponic experiment was carried out to study the effect of cadmium (Cd) on growth, Cd accumulation, lipid peroxidation, reactive oxygen species (ROS) content and antioxidative enzymes in leaves and roots of Arabis paniculata F., a new Cd hyperaccumuator found in China. The results showed that 22-89 microM Cd in solution enhanced the growth of A. paniculata after three weeks, with 21-27% biomass increase compared to the control. Cd concentrations in shoots and roots increased with increasing Cd supply levels, and reached a maximum of 1662 and 8670 mg kg(-1) Cd dry weight at 178 microM Cd treatment, respectively. In roots, 22-89 microM Cd reduced the content of malondialdehyde (MDA), superoxide (O(2)(-1)) and H(2)O(2) as well as the activities of superoxide dismutase (SOD), guaiacol peroxidase (GPX), ascorbate peroxidase (APX) and glutathione reductase (GR). In leaves, the contents of MDA, O(2)(-1) and H(2)O(2) remained unaffected by 22-89 microM Cd, while 178 microM Cd treatment significantly increased the MDA content, 69.5% higher than that of the control; generally, the activities of SOD, catalase (CAT), GPX and APX showed an increasing pattern with increasing Cd supply levels. Our present work concluded that A. paniculata has a great capability of Cd tolerance and accumulation. Moderate Cd treatment (22-89 microM Cd) alleviated the oxidative stress in roots, while higher level of Cd addition (178 microM) could cause an increasing generation of ROS, which was effectively scavenged by the antioxidative system. 相似文献
662.
Sorption of nonpolar (phenanthrene and butylate) and polar (atrazine and diuron) organic chemicals to oil-contaminated soil was examined to investigate oil effects on sorption of organic chemicals and to derive oil–water distribution coefficients (Koil). The resulting oil-contaminated soil–water distribution coefficients (Kd) for phenanthrene demonstrated sorption-enhancing effects at both lower and higher oil concentrations (Coil) but sorption-reducing (competitive) effects at intermediate Coil (approximately 1 g kg−1). Rationalization of the different dominant effects was attempted in terms of the relative aliphatic carbon content which determines the accessibility of the aromatic cores to phenanthrene. Little or no competitive effect occurred for butylate because its sorption was dominated by partitioning. For atrazine and diuron, the changes in Kd at Coil above approximately 1 g kg−1 were negligible, indicating that the presently investigated oil has little or no effect on the two tested compounds even though the polarity of the oil is much less than soil organic matter (SOM). Therefore, specific interactions with the active groups (aromatic and polar domains) are dominantly responsible for the sorption of polar sorbates, and thus their sorption is controlled by available sorption sites. This study showed that the oil has the potential to be a dominant sorptive phase for nonpolar pollutants when compared to SOM, but hardly so for polar compounds. The results may aid in a better understanding of the role of the aliphatic and aromatic domains in sorption of nonpolar and polar organic pollutants. 相似文献
663.
664.
665.
666.
667.
陕西省雷电灾害易损性分析、评估及易损度区划 总被引:7,自引:2,他引:5
根据2002~2007年陕西省10个市的雷暴日和雷电灾害统计资料,结合陕西各市的经济和人口密度特征,提出了雷暴日数、雷电灾害频度、生命易损模数及经济易损模数作为各市雷电灾害易损性评估指标,并在此基础上,给出了陕西各市雷电灾害易损度评估结构.采用四级分区法对上述雷电灾害易损性评估指标进行了分级,并赋予各等级如下定值:极高级为1.0、高级为0.8、中级为0.5、低级为0.2.将陕西省10市按照四个雷电灾害易损性评估指标的所属等级获取相应等级值,将各市四个评估指标的等级值累加得到平均值作为雷电灾害易损性评估的评价指数,并利用上述四级分区法形成陕西省雷电灾害易损度区划. 相似文献
668.
669.
670.
非饱和土土-水特征曲线(SWCC)表示了土中含水量与吸力之间的关系。针对非饱和土干-湿循环过程中的吸力变化特征,开展试验研究。采用体积压力板仪实现非饱和土的脱湿和吸湿过程。试验成果显示:(1)土-水特征曲线是不稳定的,它与土体含水率的变化路径有关;(2)在干湿循环过程中,相同的基质吸力具有不同的含水量。 相似文献