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   14126篇
  免费   33篇
  国内免费   10篇
安全科学   84篇
废物处理   942篇
环保管理   1450篇
综合类   2557篇
基础理论   3997篇
环境理论   8篇
污染及防治   2850篇
评价与监测   1217篇
社会与环境   1055篇
灾害及防治   9篇
  2022年   37篇
  2019年   54篇
  2018年   1528篇
  2017年   1426篇
  2016年   1267篇
  2015年   218篇
  2014年   148篇
  2013年   222篇
  2012年   569篇
  2011年   1488篇
  2010年   823篇
  2009年   741篇
  2008年   1075篇
  2007年   1397篇
  2006年   182篇
  2005年   162篇
  2004年   173篇
  2003年   181篇
  2002年   249篇
  2001年   127篇
  2000年   94篇
  1999年   64篇
  1998年   59篇
  1997年   53篇
  1996年   54篇
  1995年   62篇
  1994年   59篇
  1993年   38篇
  1992年   47篇
  1991年   47篇
  1990年   41篇
  1989年   34篇
  1984年   42篇
  1982年   31篇
  1981年   34篇
  1976年   33篇
  1967年   35篇
  1966年   32篇
  1965年   50篇
  1964年   37篇
  1963年   36篇
  1962年   34篇
  1961年   46篇
  1960年   39篇
  1959年   41篇
  1958年   46篇
  1957年   39篇
  1956年   40篇
  1955年   37篇
  1954年   43篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
The chemical recycling of cellulosic fibres may represent a next-generation fibre–fibre recycling system for cotton textiles, though remaining challenges include how to accommodate fibre blends, dyes, wrinkle-free finishes, and other impurities from finishing. These challenges may disrupt the regeneration process steps and reduce the fibre quality. This study examines the impact on regenerated viscose fibre properties of a novel alkaline/acid bleaching sequence to strip reactive dyes and dimethyloldihydroxyethyleneureas (DMDHEU) wrinkle-free finish from cotton textiles. Potentially, such a bleaching sequence could advantageously be integrated into the viscose process, reducing the costs and environmental impact of the product. The study investigates the spinning performance and mechanical properties (e.g., tenacity and elongation) of the regenerated viscose fibres. The alkaline/acid bleaching sequence was found to strip the reactive dye and DMDHEU wrinkle-free finish from the cotton fabric, so the resulting pulp could successfully be spun into viscose fibres, though the mechanical properties of these fibres were worse than those of commercial viscose fibres. This study finds that reactive dyes and DMDHEU wrinkle-free finish affect the viscose dope quality and the regeneration performance. The results might lead to progress in overcoming quality challenges in cellulosic chemical recycling.  相似文献   
2.
The discovery of ordered mesoporous materials in 1992 by Mobil Oil Corporation scientists has opened great opportunities for new applications in many emerging fields such as heterogeneous catalysis, biocatalysis, energy conversion, biosensors, photocatalytic devices and environmental technologies. Porous materials are grouped by the International Union of Pure and Applied Chemistry (IUPAC) into three classes according to their pore diameter: microporous (<?2 nm), mesoporous (2–50 nm) and macroporous (>?50 nm). One of the most versatile methods for the preparation of those materials is the soft template approach which combines the sol–gel process with molecular self-assembly. While the micelles formed by ionic or nonionic surfactants, as well as amphiphilic polymers, have been extensively used as templates, the supramolecular assemblies formed between cyclodextrins and block copolymers have been less investigated, despite their large chemical and structural diversity. This review article focuses mainly on nanostructured porous inorganic materials derived from cyclodextrins or cyclodextrin-based assemblies. More than 100 references are described and discussed, in which we look both at their synthesis and characterization, as well as their applications in the emerging fields of heterogeneous catalysis and photocatalysis. A special attention is paid to the evaluation of the critical parameters that need to be controlled for improving their (photo) catalytic performances.  相似文献   
3.
4.
5.
The purpose of the research is to identify the critical challenges that are impeding the adoption of e-mobility in India. It also aims to give a roadmap how to address these challenges while taking into considerations concerns of all the relevant stakeholders. Based on an in-depth literature review, an exploratory research design is employed to delve deep into various aspects of e-mobility. This is followed by a three-phase Delphi technique to identify and rate the e-mobility challenges in the Indian context. The study successfully identifies four different categories of challenges and proposes integrative framework for e-mobility. Further, the research goes on to lay out the future roadmap for mass adoption of electric vehicles (EVs) in India. The research is novel in terms of presenting a holistic viewpoint on e-mobility in India. Its originality lies in identifying the major inhibitors obstructing EVs adoption in India and then suggesting the roadmap how to overcome these impediments for mass adoption of e-mobility.  相似文献   
6.
7.
8.
9.
10.
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