全文获取类型
收费全文 | 2363篇 |
免费 | 330篇 |
国内免费 | 789篇 |
专业分类
安全科学 | 377篇 |
废物处理 | 69篇 |
环保管理 | 187篇 |
综合类 | 1800篇 |
基础理论 | 367篇 |
污染及防治 | 271篇 |
评价与监测 | 134篇 |
社会与环境 | 150篇 |
灾害及防治 | 127篇 |
出版年
2024年 | 19篇 |
2023年 | 46篇 |
2022年 | 164篇 |
2021年 | 139篇 |
2020年 | 147篇 |
2019年 | 115篇 |
2018年 | 95篇 |
2017年 | 152篇 |
2016年 | 107篇 |
2015年 | 118篇 |
2014年 | 150篇 |
2013年 | 205篇 |
2012年 | 227篇 |
2011年 | 218篇 |
2010年 | 208篇 |
2009年 | 190篇 |
2008年 | 181篇 |
2007年 | 191篇 |
2006年 | 179篇 |
2005年 | 141篇 |
2004年 | 102篇 |
2003年 | 77篇 |
2002年 | 79篇 |
2001年 | 58篇 |
2000年 | 61篇 |
1999年 | 40篇 |
1998年 | 19篇 |
1997年 | 16篇 |
1996年 | 12篇 |
1995年 | 9篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有3482条查询结果,搜索用时 15 毫秒
271.
引入生态可持续性指数,在风险矩阵的框架下与土地生态安全指数相结合,构建了土地生态安全二维预警模型,并应用于临湘市土地生态安全预警.研究表明:土地生态安全指数逐年上升,土地生态系统自身稳定性及其对社会经济发展的支撑能力不断提高;生态可持续性指数逐年下降,土地生态系统对社会经济发展的支撑能力的可持续性逐渐减弱,如不采取相应措施,未来将难以避免跌入不可持续状态;2005~2019年土地生态安全警情呈“中警-轻警-中警-轻警”的波折变化,最终稳定为轻警,预测2020~2025年将延续轻警,跌入重警的可能性较小,但仍存在跌回中警的风险.临湘市应通过发展生态友好型产业、加大环保投入、有序扩张第二产业和建设用地、节制消费和应用新技术提高生产力等措施,综合改善土地生态安全状况.研究认为二维预警模型可有效避免传统模型预警失真的问题,有利于提高土地生态安全预警结果的全面性、前瞻性和合理性. 相似文献
272.
Mingjie Zhang Gang Yang Shuai Liu Jiahui Yu Hongzhe Li Liwen Zhang Yipei Chen Ruitang Guo Tao Wu 《环境科学学报(英文版)》2022,34(6):163-174
Due to the ever-tightening regulation on mercury emission in recent decades, there is an urgent need to develop novel materials for the removal of elemental mercury at coal-fired power plants. In this study, a series of MoS2 quantum dots (QDs)-based MoS2/HKUST-1 composite materials were prepared. It is found that MoS2 QDs were encapsulated by HKUST-1 and enhanced the crystallinity and specific surface area of HKUST-1. The MoS2/HKUST-1 showed excellent performance in catalytic oxidation of Hg0 as compared with pristine HKUST-1. It is found that surface layer of lattice oxygens is active and participates in Hg0 oxidation, while the consumption of surface oxygens then leads to the formation of oxygen vacancies on the surface. These vacancies are effective in the adsorption and dissociation of O2, which subsequently participates in the oxidation of Hg0. Moreover, the study on the influence of commonly seen gas components, such as SO2, NO, NH3 and H2O, etc., on Hg0 oxidation demonstrated that synergistic effects exist among these gas species. It is found that the presence of NO promotes the oxidation of Hg0 using oxygen as the oxidant. 相似文献
273.
274.
土壤微生物决定着土壤生态系统的养分周转状况,其死生物物质在土壤有机碳(SOC)积累中发挥关键作用.然而,目前缺乏对土壤微生物群落丰度及其死生物物质如何响应农业土地集约利用程度调整的了解.为弥补这一知识缺口,基于土地集约化利用程度,设置小麦-玉米周年轮作(CC)、临时草地与小麦种植交替(TG)和多年生草地(PG)这3个处理开展长期定位试验,采用基于数字PCR和微生物标志物氨基糖的检测技术,以探究农业土地集约利用程度调整对土壤细菌和真菌数量,以及细菌、真菌和总微生物死生物物质C积累及其对土壤SOC封存贡献的影响,进一步明确驱动细菌、真菌和总微生物死生物物质C积累的关键因子.结果表明,与土壤细菌群落丰度相比,真菌群落丰度受到农业土地集约利用程度调整的强烈影响,随土地集约利用程度的降低而增加.在3种土地集约利用程度处理下,土壤总微生物死生物物质C均主导SOC积累,对SOC的贡献率分别达到52.78%、 58.36%和68.87%,呈现随土地集约利用程度降低而升高的趋势;真菌死生物物质C占总微生物死生物物质C的比例均大于80%,说明其对总微生物死生物物质C的绝对主导地位,且受土地集约利用程度降低... 相似文献
275.
生物炭和秸秆还田对微咸水滴灌棉田土壤真菌群落结构多样性的影响 总被引:4,自引:4,他引:0
微咸水灌溉增加土壤盐分,改变土壤环境,进而影响土壤真菌的结构和多样性.在长期微咸水灌溉的基础上,分别添加生物炭和秸秆(采用等碳量设计,分别为3.7 t·hm-2和6 t·hm-2),探究生物炭和秸秆对土壤理化性质和真菌群落结构多样性的影响.结果表明:与不施生物炭和秸秆(对照)相比,生物炭施用显著增加土壤的pH、全碳、速效钾和速效磷含量,但显著降低土壤电导率,降低幅度为20.71%;秸秆处理显著增加土壤的速效钾和速效磷含量,但显著降低土壤容重和电导率,降低幅度为4.17%和64.50%.生物炭和秸秆处理对真菌群落Chao1指数和ACE指数有增加趋势,对Shannon指数和Simpson指数有降低趋势.土壤优势真菌门类为子囊菌门、被孢霉门、担子菌门、壶菌门和球囊菌门;优势真菌属为毛壳菌属、赤霉菌属、镰刀菌属、Idriella和被孢霉属.施加生物炭和秸秆提高子囊菌门、被孢霉门、担子菌门、球囊菌门和毛壳菌属的相对丰度;但降低壶菌门、赤霉菌属和Idriella的相对丰度.LEfSe分析表明,施用生物炭和秸秆还田降低真菌群落潜在生物标志物数量.RDA结果显示,土壤真菌群落结构与EC1:5和TN显著相关.微咸水灌溉给土壤带来了不利影响,其中EC1:5和TN是驱动土壤真菌群落结构变化的主要因子,土壤真菌群落通过生物炭和秸秆对土壤的改良作用来适应盐胁迫环境. 相似文献
276.
某钢铁企业高炉炼铁车间的出铁场在生产过程中产生大量高浓度的烟尘,对厂区的大气环境及周边的环境造成严重污染,同时直接危害了职工的身体健康。通过对整个出铁场除尘工艺系统及通风状况的分析及实际应用情况,总结出了适合该场合的系统除尘方案。 相似文献
277.
278.
279.
BO PAN BAOSHAN XING WENXIN LIU SHU TAO XIUMEI LIN YANXV ZHANG 《Journal of environmental science and health. Part. B》2013,48(8):1333-1347
Sorption characteristics of phenanthrene (PHE) were studied on eight soils with organic carbon contents spanning over an order of magnitude using phase distribution relationships (PDRs) at 1 h, 48 h, and 720 h contact times. A new algebraic method was employed to describe the sorption characteristics at different time intervals (between 1 h and 48 h, and 1 h and 720 h). It was found that nonlinearity increased with increasing contact time and sorption that occurred in the subsequent time interval following the initial 1 h exhibited stronger isotherm nonlinearity. Sorption coefficients were positively correlated with the organic carbon contents of the soils. Detailed sorption dynamics were also examined on these soils. A two-compartment, first-order model was used to describe the sorption dynamics. The rate constants of the two compartments differed 18–170 times, suggesting the dissimilar sorption behaviors of the mathematically separated compartments. These two compartments were labeled fast and slow sorption compartment according to the rate constants. Calculation showed that the fast compartment accounted for over 80% of the overall sorption at the initial 1 h, while the slow compartment predominated the total sorption in the following 47 h. By combining the discussion of PDRs and sorption dynamics, the contributions of the two compartments to linear and nonlinear sorption were differentiated. The slow sorption compartment made a major contribution to nonlinear sorption and possibly to sequestration of organic pollutants by these soils. 相似文献
280.
Zhang Yong Xiao Gang Wang Guanxing Zhou Tao Jiang Dawei 《Waste management (New York, N.Y.)》2009,29(4):1376-1382
Medical waste management is of great importance due to its infectious and hazardous nature that can cause undesirable effects on humans and the environment. The objective of this study was to analyze and evaluate the present status of medical waste management in the light of medical waste control regulations in Nanjing. A comprehensive inspection survey was conducted for 15 hospitals, 3 disposal companies and 200 patients. Field visits and a questionnaire survey method were implemented to collect information regarding different medical waste management aspects, including medical waste generation, segregation and collection, storage, training and education, transportation, disposal, and public awareness.The results indicated that the medical waste generation rate ranges from 0.5 to 0.8 kg/bed day with a weighted average of 0.68 kg/bed day. The segregated collection of various types of medical waste has been conducted in 73% of the hospitals, but 20% of the hospitals still use unqualified staff for medical waste collection, and 93.3% of the hospitals have temporary storage areas. Additionally, 93.3% of the hospitals have provided training for staff; however, only 20% of the hospitals have ongoing training and education. It was found that the centralized disposal system has been constructed based on incineration technology, and the disposal cost of medical waste is about 580 US$/ton. The results also suggested that there is not sufficient public understanding of medical waste management, and 77% of respondents think medical waste management is an important factor in selecting hospital services.The problematic areas of medical waste management in Nanjing are addressed by proposing some recommendations that will ensure that potential health and environmental risks of medical waste are minimized. 相似文献