首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2529篇
  免费   187篇
  国内免费   890篇
安全科学   186篇
废物处理   145篇
环保管理   210篇
综合类   1256篇
基础理论   494篇
污染及防治   971篇
评价与监测   124篇
社会与环境   95篇
灾害及防治   125篇
  2024年   21篇
  2023年   62篇
  2022年   137篇
  2021年   97篇
  2020年   83篇
  2019年   90篇
  2018年   82篇
  2017年   109篇
  2016年   139篇
  2015年   176篇
  2014年   219篇
  2013年   265篇
  2012年   196篇
  2011年   210篇
  2010年   192篇
  2009年   167篇
  2008年   163篇
  2007年   128篇
  2006年   148篇
  2005年   102篇
  2004年   89篇
  2003年   77篇
  2002年   85篇
  2001年   112篇
  2000年   74篇
  1999年   70篇
  1998年   72篇
  1997年   51篇
  1996年   39篇
  1995年   36篇
  1994年   30篇
  1993年   21篇
  1992年   18篇
  1991年   7篇
  1990年   14篇
  1989年   3篇
  1988年   5篇
  1987年   6篇
  1986年   4篇
  1985年   2篇
  1984年   2篇
  1983年   2篇
  1982年   1篇
排序方式: 共有3606条查询结果,搜索用时 15 毫秒
881.
IMPLICATIONS: During the production of penicillin, a mass of waste bacterial residue is generated. In the past, the bacterial residues have been used for food additives. Unfortunately, doubts of their suitability as a feedstock have been raised because of the small amount of antibiotics and the degradation products remaining in the bacterial residues. So, penicillin bacterial residue is one of the hazardous wastes. Therefore, penicillin bacterial residue should be managed in accordance with the hazardous waste. To get a right method, the penicillin bacterial residue was characterized.  相似文献   
882.
883.
884.
Environmental Science and Pollution Research - Fusarium wilt caused by the fungus Fusarium oxysporum f. sp. cucumerinum (FOC) is the most severe soil-borne disease attacking cucumber. To assess the...  相似文献   
885.
Hydrotalcite and its calcination product were used to treat pure water spiked with various concentrations of boron and geothermal water containing boron as a major undesirable element. The kinetics process of boron sorption by uncalcined hydrotalcite is controlled by the diffusion of boron from bulk solution to sorbent-solution boundary film and its exchange with interlayer chloride of hydrotalcite, whereas the removal rate of boron by calcined hydrotalcite rests with the restoration process of its layered structure. The results of isotherm sorption experiments reveal that calcined hydrotalcite generally has much stronger ability to lower solution boron concentration than uncalcined hydrotalcite. The combination of adsorption of boron on the residue of MgO–Al2O3 solid solution and intercalation of boron into the reconstructed hydrotalcite structure due to “structural memory effect” is the basic mechanism based on which the greater boron removal by calcined hydrotalcite was achieved. As 15 geothermal water samples were used to test the deboronation ability of calcined hydrotalcite at 65 °C, much lower boron removal efficiencies were observed. The competitive sorption of the other anions in geothermal water, such as HCO3 ?, SO4 2?, and F?, is the reason why calcined hydrotalcite could not remove boron from geothermal water as effectively as from pure boron solution. However, boron removal percents ranging from 89.3 to 99.0 % could be obtained if 50 times of sorbent were added to the geothermal water samples. Calcined hydrotalcite is a good candidate for deboronation of geothermal water.  相似文献   
886.
成都市生态城市建设的路径设计   总被引:5,自引:0,他引:5  
文章结合成都市自然资源的优势和特点,依据生态原理的基本思想,从城市河流生态的保护与建设;成都绿化的生态建设与城市生态社区示范建设;城乡融合生态系统的基本设计;成都郊县市生态农业、生态聚落的建设和生态建设总体布局与功能分区等五个方面进行了具体的分析,提出了相关的设计路径和措施。  相似文献   
887.
888.
• Aquatic plants are more likely to absorb TiO2 NPs that are beneficial to them. • Ag NPs inhibited the growth of aquatic plants under both 5- and 60-day exposure. • CeO2 NPs had positive/negative impact on plant in 5/60-day exposure, respectively. • TiO2 NPs presence could enhance the photosynthesis and increase the plant biomass. • The ENPs changed plant activity, which resulted in changes of wetland performance. Engineered nanoparticles (ENPs) threaten the environment through wastewater discharging. Generally, constructed wetlands (CWs) are efficient methods for ENPs removal. However, the biotoxicity of ENPs on plants in CWs is unclear. Here, we investigated the distribution and bio-impacts of different ENPs (Ag NPs, TiO2 NPs, and CeO2 NPs) in plants under 5- and 60-day exposure to 1 and 50 mg/L concentrations. Results showed that ENPs appeared in the vascular bundle and mesophyll cell space, which induced the variation in antioxidase activities (e.g., superoxide dismutase [SOD], peroxidase [POD], and catalase [CAT] activities) as well as overproduction of malondialdehyde (MDA). Additionally, Ag NPs inhibited photosynthesis rate and root activity during two exposure phases. CeO2 NPs had positive and negative impacts on plants in 5- and 60-day exposure, respectively. Inversely, TiO2 NPs enhanced photosynthesis and root activity under 60-day exposure. Finally, the contents of the C, N, and P elements in plants fluctuated in response to ENPs stress. All results have a positive correlation with the wetland performance under ENPs exposure except for TiO2 NPs treatment. Overall, our study systematically reveals aquatic plants' responses to ENPs and provides a reference for building ecological treatment systems to purify wastewater containing ENPs.  相似文献   
889.
滇缅大震与长江巨洪的遥相关   总被引:10,自引:0,他引:10  
长江、珠江巨大洪水的预测对国计民生关系甚大。本文提出了滇缅地区7级以上大震发生后一年内长江和珠江有可能发生巨洪的预测指标。这一点和后来某些气象学家得到的青藏高原南部(95°E以西)超前异常增温与江淮巨洪有关的结果是一致的,可以说这是相互验证。但这些气象学家未讨论增温的原因,我们的研究则包含这个问题的回答。另外在预测北方旱涝时也要考虑滇缅地区的大震发生与否。  相似文献   
890.
本文提供了被认为比较准确的32种有机分子特征基团红外光谱吸收范围;提出了红外仪扫描时计算机同时采集数据,红外扫描结束后,计算机不用人工干予自动利用有机分子基团的特征吸收峰的峰位、强度信息判断有机分子所含基团的图谱解析方法。并提供了程序设计框图。给出了40个较有代表性化合物的图谱解析实验结果。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号