全文获取类型
收费全文 | 413篇 |
免费 | 48篇 |
国内免费 | 151篇 |
专业分类
安全科学 | 46篇 |
废物处理 | 15篇 |
环保管理 | 47篇 |
综合类 | 239篇 |
基础理论 | 58篇 |
环境理论 | 6篇 |
污染及防治 | 98篇 |
评价与监测 | 10篇 |
社会与环境 | 71篇 |
灾害及防治 | 22篇 |
出版年
2024年 | 1篇 |
2023年 | 14篇 |
2022年 | 20篇 |
2021年 | 16篇 |
2020年 | 11篇 |
2019年 | 29篇 |
2018年 | 47篇 |
2017年 | 37篇 |
2016年 | 29篇 |
2015年 | 31篇 |
2014年 | 30篇 |
2013年 | 54篇 |
2012年 | 32篇 |
2011年 | 25篇 |
2010年 | 23篇 |
2009年 | 27篇 |
2008年 | 16篇 |
2007年 | 30篇 |
2006年 | 28篇 |
2005年 | 21篇 |
2004年 | 13篇 |
2003年 | 12篇 |
2002年 | 16篇 |
2001年 | 12篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1993年 | 3篇 |
1990年 | 2篇 |
1987年 | 3篇 |
1982年 | 1篇 |
1974年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有612条查询结果,搜索用时 263 毫秒
1.
Wildlife provides food, medicine, clothing, and other necessities for humans, but overexploitation can disrupt the sustainability of wildlife resources and severely threaten global biodiversity. Understanding the characteristics of consumer behavior is helpful for wildlife managers and policy makers, but the traditional survey methods are laborious and time-consuming. In contrast, culturomics may more efficiently identify the features of wildlife consumption. As a case study of the culturomics approach, we examined tiger bone wine consumption in China based on social media and Baidu search engine data. Tiger bone wine is one of the most purchased tiger products; its consumption is closely related to tiger poaching, which greatly threatens wild tiger survival. We searched a popular social media website for the term “tiger bone wine” and focused on posts that were originally created from 1 January 2012 to 31 December 2018. We filtered and classified posts related to the purchase, sale, or consumption of tiger bone wine and extracted information on providers, consumption motivations, year of production, and place of origin of the tiger bone wines based on the texts and photos of these posts. We found 756 posts related to tiger bone wine consumption, 113 of which mentioned providers of tiger bone wine, including friends (53%), elder relatives (37%), peer relatives (7%), and others (3%). Out of the 756 posts, 266 indicated the motivations of tiger bone wine consumption. Tiger bone wines were consumed as a tonic (34%), medicine (23%), game product (30%), and a symbol of wealth (28%). Some posts indicated ≥2 consumption motivations. These findings were consistent with the search queries from Baidu index. Such information could help develop targeted strategies for tiger conservation. The culturomics approach illustrated by our study is a rapid and cost-efficient way to characterize wildlife consumption. 相似文献
2.
Kristie Byrum 《Environmental Communication: A Journal of Nature and Culture》2019,13(2):209-221
This study addresses the use of message carriers to convey corporate social responsibility information to promote eco-purchasing involvement. The work tests various media formats transmitted via social media. The effects of corporate vs. peer communication in a corporate social responsibility campaign in stimulating self-reported eco-purchasing involvement are indicated. The research varies communication dimensions of a fictional corporate social responsibility campaign sent through social media. Multiple media formats; new release; article; and advertisement were tested, as was the inclusion of social media persuasive sentiment. The analysis of source/format combinations and source/format/sentiment combinations found statistically significant differences for consumer-to-consumer communication in stimulating eco-purchasing involvement in certain circumstances. This research suggests an emerging role for the consumer communicator as a content co-creator and validates the effective use of articles and news releases instead of advertising on social media, yielding managerial and scholarly implications. 相似文献
3.
亲水性多孔载体在流化床中的生物膜形成过程分析 总被引:2,自引:0,他引:2
采用实验制备的一种新型亲水性多孔聚合物作为流化床反应器中生物膜附着生长的载体,实现流态化水力条件下的生物挂膜过程.在3个结构尺寸相同的流化床反应器中考察了接种污泥浓度、进水有机负荷及载体粒径对亲水性多孔载体生物挂膜量的影响,试验结果表明,接种污泥浓度为30 g VSS/L、进水TOC值为350 mg/L、载体粒径为5~8 mm时载体表面的附着生物量最大,反应器运行12 d的载体附着生物量达到4.45 g VSS/L,膜结构稳定,表现出较活性污泥法更高的活性.在进水TOC、氨氮浓度分别为350 ms/L、50 mg/L,HRT为6 h的情况下,两者的去除率分别达到了97.1%和64.3%,表明载体上的生物膜对污水中TOC及氨氮的去除表现出高效率.挂膜后载体表面上的微生物以丝状菌为主,孔壁上的微生物以球菌和杆菌为主要生物相,证明载体内外表面皆适宜微生物的生长,并且形成合理的生物相分布. 相似文献
4.
传统工艺的塑料生产不仅依赖石油资源的持续开发利用,同时给环境造成了前所未有的压力,近年来生物基聚合物(聚(3-羟基-3-戊酸酯)-PHBV,聚乳酸-PLA)日渐成为传统石油基塑料的替代产品.本文采用呼吸测试手段,旨在揭示均质复合材料在不同环境介质(土壤、熟化堆肥、水体)条件下及有机添加剂(木质素),无机添加剂(蒙脱石)和天然有机物链增长剂(Joncryl)作用下的生物降解特征.结果表明:当链增长剂Joncryl添加量为5%时,对所有介质PHBV和PLA复合材料产生显著抑制作用.Joncryl添加量为0.2%时,未对所测样品的生物降解行为产生干扰作用.在熟化堆肥介质中,PLA复合材料比PHBV基质混合物的生物降解速率明显降低.有机木质纤维添加剂(榛子壳粉末)单独在聚合物中添加或者和链增长剂Joncryl以及非有机添加剂(Dellite72T)共同作用下都可促进PLA聚合物中各组分的相容连接性.实验结果表明,新型添加剂在不同介质中以二元或三元添加的方式对生物降解过程产生重要影响,该研究将为新型材料使用后的生物降解效应提供理论依据. 相似文献
5.
Fence for traffic noise control sometimes causes adverse effect on air pollution. Thus in this study, performance of porous fence as a tool for control of both air pollution and noise pollution was evaluated. A two-dimensional numerical model for flow and pollutant concentration and an analytical model for traffic noise were utilized in the analysis of a double-decked road structure with fences only at ground (Case 1) and at both ground and upper deck (Case 2). Porous fences were assumed only at the ground level since the solid fences at the upper deck usually leads to desirable result on air pollution. Effects of the variable porosity on air quality and noise level near road were evaluated. Obtained results showed: (1) flow pattern in leeward of fence was drastically changed at 40–50% porosity in Case 1 and 50% in Case 2. The porosity larger than 40% excluded presence of a circulation behind the fence. (2) Effect of porous fence on air pollution was different in Cases 1 and 2. In Case 1, the porous fence generally resulted in the reduction of air pollution at the ground level; on the other hand, in Case 2, it rather led to increase of the concentration. (3) Traffic noise level was also largely changed by the porosity of the fence; an example of simultaneous evaluation of the effects of porous fence on both air and noise pollution in Case 1 showed that the fence of 60% porosity leads to reduction of air pollution by 20% compared with solid fence case, and reduction of noise pollution by 4–6% in dB compared with no fence case, at l m high and 10 m from the road. 相似文献
6.
7.
比较了3种生物接触氧化法对富营养化水源水中藻类的去除效果,探讨其去除藻类的途径。试验结果表明:淹没式曝气生物陶粒滤池(I型)在4-6m/h过滤速度条件下,对藻类总数的去除效率稳定,平均为70%左右;采用YDT弹性立体填料的中心导流筒曝气生物接触氧化法(Ⅱ型)与直接微孔曝气生物接触氧化法(Ⅲ型),在试验初期对藻类总数的去除率较低,平均去除率分别为60.2%、51.6%。但随着生物膜厚度的增加,试验后期对藻类的去除效果逐步得到提高,平均达70%以上。生物膜对藻类的生物絮凝、吸附、生物膜的脱落沉降等是生物接触氧化法去除藻类的主要途径。 相似文献
8.
9.
10.
通过构建水生动物-人工介质新型生态系统来研究太湖水源地水质改善效果.中试试验结果表明,对比3d和7d的水力停留时间(HRT),当HRT:7d,系统对TN、NO2--N、NO3--N、TP、PO4--P的平均去除率可分别达到79.00%、63.46%、14.57%、67.43%、35.81%;对比空白池,TN、NO2--N、NO3--N、TP、PO4--P的平均去除率仅为9.67%、7.09%、1.30%、9.92%、7.04%.通过该系统中水生动物的吸收和人工介质上微生物降解的协同作用,使得氮磷类污染物的去除效果明显.可见,水生动物-人工介质生态系统对改善太湖水源地水质有良好的效果,对构建安全的水源地生态系统具有积极的意义. 相似文献