全文获取类型
收费全文 | 1116篇 |
免费 | 66篇 |
国内免费 | 460篇 |
专业分类
安全科学 | 77篇 |
废物处理 | 62篇 |
环保管理 | 100篇 |
综合类 | 645篇 |
基础理论 | 242篇 |
污染及防治 | 361篇 |
评价与监测 | 35篇 |
社会与环境 | 36篇 |
灾害及防治 | 84篇 |
出版年
2024年 | 1篇 |
2023年 | 17篇 |
2022年 | 58篇 |
2021年 | 51篇 |
2020年 | 40篇 |
2019年 | 35篇 |
2018年 | 52篇 |
2017年 | 52篇 |
2016年 | 56篇 |
2015年 | 81篇 |
2014年 | 94篇 |
2013年 | 117篇 |
2012年 | 113篇 |
2011年 | 114篇 |
2010年 | 81篇 |
2009年 | 74篇 |
2008年 | 78篇 |
2007年 | 68篇 |
2006年 | 57篇 |
2005年 | 52篇 |
2004年 | 26篇 |
2003年 | 33篇 |
2002年 | 31篇 |
2001年 | 30篇 |
2000年 | 31篇 |
1999年 | 27篇 |
1998年 | 29篇 |
1997年 | 27篇 |
1996年 | 24篇 |
1995年 | 27篇 |
1994年 | 11篇 |
1993年 | 9篇 |
1992年 | 11篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有1642条查询结果,搜索用时 15 毫秒
121.
Enhancement of solubilization and acidification of waste activated sludge by pretreatment 总被引:2,自引:0,他引:2
The effects of various pretreatment methods, including thermo-acid, thermo-alkaline, ultrasonic-alkaline and ultrasonic-acid, on solubilization and subsequent acidification efficiency of waste activated sludge (WAS) were investigated. The results showed that both thermo-alkaline and ultrasonic-alkaline significantly improved the solubilization of WAS at a high concentration (7.4% of total solids). Solubilization of volatile solids (VS) and crude protein was 60.2-61.6% and 66.8-67.5%, respectively. Thermo-alkaline or ultrasonic-alkaline pretreatment also enhanced the efficiency of subsequent WAS acidification. Experimental results showed that they had similar effects on the acidification of WAS. The conversion ratio from VS to total volatile fatty acids (TVFAs) was 0.230 in the case of the ultrasonic-alkaline pretreatment. Through this pretreatment, the level of TVFAs was 68% more than the untreated WAS after 252 h of fermentation. The mechanism of TVFAs production under different pretreatment methods was further investigated and the results indicated that soluble protein was the main substrate for TVFAs production from the WAS after the thermo-alkaline or ultrasonic-alkaline pretreatment. 相似文献
122.
Du Yu Wang Chuansheng Fan Jie 《中国人口.资源与环境(英文版)》2007,5(4):64-73
With the further development of socialist market economy, the mobility of factor markets in China, especially the labor market, is strengthened. Externalities interacts with the agglomeration of productive factors. Under the framework of new economic geography, this article presents a theoretical model involving the endogenous population density affected by urban externalities. Results show that the population density is more concentrated around the center because the degree and extent of interaction between individuals intensifies when the distance from the center decreases. When there are several externalities resources, the aggregation of externalities changes the configuration of spatial factor allocation. These results fit well with the empirical facts about the decreasing density of floating population along the cities of Guangzhou, Dongguan and Shenzhen in Guangdong Province which is situated in the eastern coast of the Pearl River Delta. We fred that under the impacts of externalities released from Hong Kong into the coast, floating population was more concentrated around Shenzhen and Dongguan, which are more adjacent to Hong Kong compared with Guangzhou City. 相似文献
123.
Cai Kui Du Juan Dai Cong Hu Huabin . Center for Rural Development Studies Yunnan University Kunming Yunnan China . Institute of Ethnology Yunnan Academy of Social Science Kunming Yunnan China . Institute of Economics Yunnan Academy of Social Science Kunming Yunnan China . Xishuangbanna Tropical Botany Garden Chinese Academy of Sciences Kunming Yunan China 《中国人口.资源与环境(英文版)》2007,5(2):78-83
A three-year study over the Bai, Jingpo and Huayaodai communities in Yunnan Province reveals that the community development is significantly influenced in various ways by such cultural factors as the concepts of development; concepts and traditions of inter-community relationships, consumption, mar- riage and gender; patterns of decision-making and production, resource and income allocation; as well as the role of information dissemination systems, religion and ritual. Based on the analysis over the interactive relevance between each factor and community development, some strategies and methods for dealing with such a cultural relevance in development projects are recommended. 相似文献
124.
Microcystin-LR(MC-LR) is the most abundant and toxic microcystin congener and has been classified as a potential human carcinogen(Group 2B) by the International Agency for Research on Cancer. However, the mechanisms underlying the genotoxic effects of MC-LR during chronic exposure are still poorly understood. In the present study, human–hamster hybrid(AL) cells were exposed to MC-LR for varying lengths of time to investigate the role of nitrogen radicals in MC-LR-induced genotoxicity. The mutagenic potential at the CD59 locus was more than 2-fold higher(p 0.01) in ALcells exposed to a cytotoxic concentration(1 μmol/L) of MC-LR for 30 days than in untreated control cells, which was consistent with the formation of micronucleus. MC-LR caused a dose-dependent increase in nitric oxide(NO) production in treated cells. Moreover, this was blocked by concurrent treatment with the NO synthase inhibitor NG-methyl-L-arginine(L-NMMA), which suppressed MC-LRinduced mutations as well. The survival of mitochondrial DNA-depleted(ρ0) ALcells was markedly decreased by MC-LR treatment compared to that in ALcells, while the CD59 mutant fraction was unaltered. These results provided clear evidence that the genotoxicity associated with chronic MC-LR exposure in mammalian cells was mediated by NO and might be considered as a basis for the development of therapeutics that prevent carcinogenesis. 相似文献
125.
126.
Zrinka Dragun Marijana Erk Dušica Ivanković Roko Žaja Vlatka Filipović Marijić Biserka Raspor 《Environmental science and pollution research international》2010,17(4):977-986
Purpose
The aim of this study was to compare the level of metal contamination in two bays in the middle part of the Eastern Adriatic coastal zone in Croatia using the gills of mussels Mytilus galloprovincialis as indicator tissue. Despite the existing sources of contamination, previous studies with caged mussels only indicated moderate metal contamination of the Kaštela Bay, contrary to the Trogir Bay in which marina and shipyard present a probable source of Cu- and Zn-contamination. 相似文献127.
通过对植被混凝土室内试验结果的归纳和分析,研究了水泥掺入比、龄期和浸水条件对植被混凝土无侧限抗压强度的影响。 相似文献
128.
超声波预处理提高污泥好氧消化性能研究 总被引:4,自引:0,他引:4
为评价超声波预处理对提高污泥生物消化的作用,采用超声波预处理与好氧消化衔接,测试了污泥消化的溶解性有机物(SCOD)、TSS及蛋白酶变化过程.结果表明,污泥超声波预处理效果较好的能量密度与时间分别为12 kW/L和10 min,此时有机物释放与能量输入之比较优;在此条件下,经预处理后的污泥好氧消化性能明显比未处理的高.消化时间为10.5 d时,经超声波预处理的污泥TSS减量42.7%,而未处理的污泥仅减量20.9%.经超声波预处理后,污泥中的蛋白酶活性明显提高;同时,超声波预处理释放出较多的可溶性物质.因此,增加的可溶性物质与蛋白酶活性使得污泥迅速降解,提高了污泥好氧消化效率,缩短了污泥好氧消化时间. 相似文献
129.
130.