全文获取类型
收费全文 | 596篇 |
免费 | 29篇 |
国内免费 | 245篇 |
专业分类
安全科学 | 27篇 |
废物处理 | 43篇 |
环保管理 | 46篇 |
综合类 | 349篇 |
基础理论 | 116篇 |
环境理论 | 1篇 |
污染及防治 | 202篇 |
评价与监测 | 33篇 |
社会与环境 | 31篇 |
灾害及防治 | 22篇 |
出版年
2024年 | 1篇 |
2023年 | 10篇 |
2022年 | 33篇 |
2021年 | 25篇 |
2020年 | 11篇 |
2019年 | 22篇 |
2018年 | 22篇 |
2017年 | 25篇 |
2016年 | 29篇 |
2015年 | 25篇 |
2014年 | 43篇 |
2013年 | 53篇 |
2012年 | 45篇 |
2011年 | 46篇 |
2010年 | 39篇 |
2009年 | 38篇 |
2008年 | 42篇 |
2007年 | 34篇 |
2006年 | 47篇 |
2005年 | 26篇 |
2004年 | 22篇 |
2003年 | 27篇 |
2002年 | 37篇 |
2001年 | 19篇 |
2000年 | 30篇 |
1999年 | 22篇 |
1998年 | 18篇 |
1997年 | 17篇 |
1996年 | 16篇 |
1995年 | 10篇 |
1994年 | 14篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有870条查询结果,搜索用时 51 毫秒
461.
Yaoyang Xu Qinghua Cai Xinqin Han Meiling Shao Ruiqiu Liu 《Environmental monitoring and assessment》2010,169(1-4):237-248
We evaluated a 4-year data set (July 2003 to June 2007) to assess the trophic state and its limiting factors of Three-Gorges Reservoir (TGR), China, a large subtropical reservoir. Based on Carlson-type trophic state index (TSI)CHL, the trophic state of the system was oligotrophic (TSIS?< 40) in most months after the reservoir became operational, although both TSITP and TSITN were higher than the critical value of eutrophic state (TSIS?>?50). Using Carlson’s (1991) two-dimensional approach, deviations of the TSIS indicated that factors other than phosphorus and nitrogen limited algal growth and that nonalgal particles affected light attenuation. These findings were further supported by the significant correlation among the values of TSICHL ? TSISD and nonvolatile suspended solids and water residence time. The logarithmic model showed that an equivalent TSICHL and TSISD could be found at τ?=?54 days in the TGR (Fig. 7). Accordingly, nonalgal particulates dominated light attenuation and limited algal biomass of the reservoir when τ?<?54 days. 相似文献
462.
Characterization of mineral particles in winter fog of Beijing analyzed by TEM and SEM 总被引:1,自引:0,他引:1
Aerosol samples were collected during winter fog and nonfog episodes in Beijing. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were applied to study morphologies, sizes, and compositions of aerosol particles. TEM observation indicates that most mineral particles collected in fog episode are scavenged in fog droplets. Number–size distributions of mineral particles collected in fog and nonfog episodes show two main peaks at the ranges of 0.1–0.3 and 1–2.5 μm, respectively. Based on their major compositions, mineral particles mainly include Si-rich, Ca-rich, and S-rich. Average S/Ca ratio of mineral particles collected in fog episode is 6.11, being eight times higher than that in nonfog episodes. Development mechanism of individual mineral particles in fog droplets is proposed. It is suggested that mineral particles with abundant alkaline components (e.g., “Ca-rich” particles) occurred in air should alleviate acidic degree of fog and contribute to complexity of fog droplets in Beijing. 相似文献
463.
Xiaomin Gu Yong Xiao Shiyang Yin Xingyao Pan Yong Niu Jingli Shao Yali Cui Qiulan Zhang Qichen Hao 《Environmental monitoring and assessment》2017,189(10):514
In this study, the hydrochemical characteristics of shallow groundwater were analyzed to get insight into the factors affecting groundwater quality in a typical agricultural dominated area of the North China Plain. Forty-four shallow groundwater samples were collected for chemical analysis. The water type changes from Ca·Na-HCO3 type in grass land to Ca·Na-Cl (+NO3) type and Na (Ca)-Cl (+NO3+SO4) type in construction and facility agricultural land, indicating the influence of human activities. The factor analysis and geostatistical analysis revealed that the two major factors contributing to the groundwater hydrochemical compositions were the water-rock interaction and contamination from sewage discharge and agricultural fertilizers. The major ions (F, HCO3) and trace element (As) in the shallow groundwater represented the natural origin, while the nitrate and sulfate concentrations were related to the application of fertilizer and sewage discharge in the facility agricultural area, which was mainly affected by the human activities. The values of pH, total dissolved solids, electric conductivity, and conventional component (K, Ca, Na, Mg, Cl) in shallow groundwater increased from grass land and cultivated land, to construction land and to facility agriculture which were originated from the combination sources of natural processes (e.g., water-rock interaction) and human activities (e.g., domestic effluents). The study indicated that both natural processes and human activities had influences on the groundwater hydrochemical compositions in shallow groundwater, while anthropogenic processes had more contribution, especially in the reclaimed water irrigation area. 相似文献
464.
pH和负压对生活垃圾焚烧厂渗沥液蒸发处理的影响 总被引:3,自引:1,他引:2
生活垃圾焚烧厂贮坑渗沥液含有弱电解质类的挥发性污染物,pH和压强是影响其蒸发过程中气液相分布的主要因素,实验研究了蒸发操作压强及渗沥液初始pH对蒸发冷凝液中污染物分配的影响.结果表明,操作压强16~39kPa对冷凝液的组成基本没有影响;而pH的变化则改变了挥发性弱电解质类污染物在渗沥液中的存在形态,进而显著地改变了其在冷凝液中的分配情况.当渗沥液的初始pH为5时,冷凝液主要成份为挥发性有机酸和低碳醇类物质,不含氨氮;pH>10时,冷凝液中挥发性有机酸减少,氨氮增加.渗沥液原液经一级蒸发可显著改善其可处理性. 相似文献
465.
Yixiang Cai Zhiyong Yan Yingjuan Ou Boshang Peng Lihua Zhang Jihai Shao Yiqing Lin Jiachao Zhang 《环境科学学报(英文版)》2022,34(1):240-248
This research investigated the effects of ciprofloxacin(CIP)(0.5, 5, and 20 mg/L) on SBR systems under different carbon source conditions. Microbial community abundance and structure were determined by quantitative PCR and high-throughput sequencing, respectively.The biodegradation production of CIP and possible degradation mechanism were also studied. Results showed that CIP had adverse effects on the nutrient removal from wastewater.Compared with sodium acetate, glucose could be more effective... 相似文献
466.
467.
生态环境保护与可持续发展 总被引:3,自引:0,他引:3
简述了可持续发展提出的历史背景及其内涵,以及生态环境保护在实行可持续发展战略中的地位和作用,指出我国生态环境中存在的问题及其原因,就我国生态环境存在的问题及解决途径作了阐述。 相似文献
468.
针对常规生活污水CODCr、BOD5、氮磷浓度高的特点,以某部队驻地生活污水为例,采用改良AAO处理工艺对生活污水进行处理.介绍了该工艺的流程、设计参数及运行效果,运行结果表明,出水CODcr、BOD5、总氮、氨氮、总磷等指标可达到《城镇污水处理厂污染物排放标准》GB/T18918-2002中的一级A标准,工艺运行稳定... 相似文献
469.
The effect of nitrate concentration on sulfide-driven autotrophic denitrification in marine sediment 总被引:3,自引:0,他引:3
Copepods have been widely used to evaluate toxicity of metals present in marine environments. However, a technical difficulty is to understand the possible routes of metal uptake and to identify in which tissues or organs metals are being accumulated. Traditional techniques are hard to be employed once each organ has to be analyzed separately. Autoradiography is an alternative technique to circumvent this limitation, since metal distribution in tissues can be visualized and quantified, even in small organisms like copepods. In the present study, accumulation and distribution of 64Cu in the copepod Calanus hyperboreus was studied using autoradiography. Copepods were exposed for 2 h to copper (2.3 mg L−1; 1.08 MBq 64Cu mg−1 Cu) and then allowed to depurate for 2 h in clean seawater. Total 64Cu was determined by gamma-spectrometry after a metal exposure and a depuration period. 64Cu distribution was determined based on images generated by autoradiography. Metal accumulation was observed on all external surfaces of the copepods, being accumulated mostly on the ventral region, followed by dorsal, urossoma and internal regions. After depuration, radioactivity levels had a decrease in the sum of external body surface. Our results show that copper uptake by C. hyperboreus is fast and that a non-negligible proportion of the accumulated metal can reach internal tissues, which may lead to detrimental physiological effects. Moreover, whole-body autoradiography was demonstrated to be an efficient technique to study copper accumulation and body distribution in a very small organism such as the copepod C. hyperboreus. 相似文献
470.