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   213篇
  免费   16篇
  国内免费   166篇
安全科学   9篇
废物处理   7篇
环保管理   22篇
综合类   214篇
基础理论   68篇
污染及防治   62篇
评价与监测   7篇
社会与环境   5篇
灾害及防治   1篇
  2023年   5篇
  2022年   7篇
  2021年   11篇
  2020年   7篇
  2019年   15篇
  2018年   10篇
  2017年   9篇
  2016年   15篇
  2015年   18篇
  2014年   14篇
  2013年   41篇
  2012年   33篇
  2011年   15篇
  2010年   18篇
  2009年   15篇
  2008年   20篇
  2007年   24篇
  2006年   27篇
  2005年   18篇
  2004年   14篇
  2003年   15篇
  2002年   6篇
  2001年   6篇
  2000年   3篇
  1999年   10篇
  1998年   1篇
  1997年   2篇
  1996年   5篇
  1995年   1篇
  1994年   1篇
  1992年   3篇
  1991年   1篇
  1989年   1篇
  1988年   2篇
  1981年   1篇
  1980年   1篇
排序方式: 共有395条查询结果,搜索用时 15 毫秒
391.
The conflict between city development and urban carrying capacity is getting ever prominent. In order to study and predict the restriction factors and prominent problems in the development of the Shandong Peninsula Blue Economic Zone as well as promote the transfer of economic development pattern in this region, this study starts from four single factor carrying capacity indicators of water, earth, transportation and environment in the city and its comprehensive carrying capacity indicator, evaluates and analyzes its carrying capacity and then papooses policy suggestions for improving its carrying capacity.  相似文献   
392.
Place branding strategies play a significant role in the professional composition of landscape imagery, including the depiction of “natural” landscapes. In this paper, Brand Blue Mountains, a brand currently implemented in the Blue Mountains region (Australia), is discursively analyzed. The brand sets out an all-encompassing “Vision” defining the identity, values and personality of the World Heritage listed Blue Mountains landscape, summarized in the tagline Elevate Your Senses. This “vision” is visually translated into a strictly coordinated and copyrighted suite of logos, graphic design, color, fonts and various photographic styles. Analysis reveals that the degree of control that place brand strategists seek to exert over the visual expression of landscape identity is significant. A highly selective narrative of positive nature-based sensory experience is constructed through the holistic application of contemporary visual media. The brands' communications strategy naturalizes and reinforces a particular market-friendly version of place. The framework that brands set for the representation of landscapes overall amounts to an exercise in calculated aesthetics, whereby the form and content of landscape images of various kinds is measured to achieve the greatest market differentiation and impact which technologies allow. The result of this calculated aesthetic system, with its taglines, saturated color, careful composition and magazine-format brevity, is a reduction in the complexity of landscape representations and a perpetuation of nature stereotypes.  相似文献   
393.
This paper presents a hypothesis that could explain why blue light appears to dominate non-image-forming (NIF) ocular photoreception in marine as well as terrestrial vertebrates. Indeed, there is more and more evidence suggesting that 'novel' retinal photoreceptors, which are sensitive to blue light and were only discovered in the 1990s, could be a feature shared by all vertebrates. In our view, blue light photoreception evolved and persisted as NIF photoreception because it has been useful in the colonisation of extensive photo-dependent oceanic habitats and facilitated the move of vertebrates from an aquatic to a terrestrial environment. Because the available scattered evidence is compatible with the validity of our hypothesis, we hope that our rationale will be followed up. Indeed, it (1) involves testable predictions, (2) provides plausible explanations for previous observations, (3) unites phenomena not previously considered related to one another and (4) suggests tests that have not been carried out before. Overall, our approach not only embraces cross-disciplinary links; it, moreover, serves as a reminder of an all-embracing evolutionary history, especially with regard to a ubiquitous photoreceptive 'clockwork-blue' in marine and terrestrial vertebrates.  相似文献   
394.
稀土铒掺杂TiO_2光催化剂的吸附和光催化活性研究   总被引:5,自引:2,他引:3  
通过溶胶-凝胶法成功的制备了一系列Er3+掺杂的TiO2光催化剂,并通过XRD、DRS对催化剂进行了表征,结果表明所制催化剂为锐钛矿型,Er3+的掺杂有利于抑制晶粒生长,提高晶体的热稳定性。紫外-可见吸收(DRS)光谱证实,Er3+的掺杂增强了催化剂在可见光区域的吸收能力。吸附实验结果表明,Er3+的掺杂显著提高了橙黄I在TiO2催化剂表面的吸附能力,随掺杂量增加,吸附增强。活性实验结果表明,Er3+的掺杂显著提高了TiO2的光催化活性,最佳掺杂量为1.5%。  相似文献   
395.
以钛酸丁酯为原料,乙醇为溶剂,利用溶胶凝胶法制备纳米TiO2微粒。以紫外灯为光源,以橙黄Ⅱ、酸性品红和亚甲基蓝溶液为降解对象,实验考察了纳米TiO2微粒的光催化活性,同时比较了不同结构的染料的降解效果。结果表明:自制的纳米TiO2对染料废水具有明显的降解,不同结构的染料中,具有单偶氮结构的染料橙黄Ⅱ的降解效果最好。  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