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   603篇
  免费   71篇
  国内免费   191篇
安全科学   78篇
废物处理   35篇
环保管理   73篇
综合类   386篇
基础理论   115篇
污染及防治   105篇
评价与监测   34篇
社会与环境   28篇
灾害及防治   11篇
  2024年   2篇
  2023年   12篇
  2022年   11篇
  2021年   14篇
  2020年   18篇
  2019年   27篇
  2018年   19篇
  2017年   18篇
  2016年   34篇
  2015年   42篇
  2014年   41篇
  2013年   52篇
  2012年   60篇
  2011年   60篇
  2010年   51篇
  2009年   55篇
  2008年   33篇
  2007年   30篇
  2006年   52篇
  2005年   14篇
  2004年   20篇
  2003年   29篇
  2002年   22篇
  2001年   35篇
  2000年   24篇
  1999年   11篇
  1998年   11篇
  1997年   11篇
  1996年   5篇
  1995年   16篇
  1994年   6篇
  1993年   5篇
  1992年   6篇
  1991年   2篇
  1990年   5篇
  1989年   1篇
  1988年   2篇
  1987年   1篇
  1986年   1篇
  1985年   3篇
  1980年   1篇
  1977年   1篇
  1972年   1篇
  1971年   1篇
排序方式: 共有865条查询结果,搜索用时 875 毫秒
381.
煤矿抽采出的低浓度瓦斯直接排空不仅浪费清洁能源而且加剧温室效应。离子液体(IL)是近年来用于气体分离的热点研究对象。综述了利用IL分离气体,特别在溶解CH_4气体方面的研究进展,归纳了具有高效溶解CH4能力的IL结构特征,以及阴阳离子对IL溶解CH_4的影响规律。分析结果表明CH_4在大部分ILs中的溶解度较小;与咪唑类ILs相比,阴离子为[FAP]~-、[doc]~-、[Tf_2N]~-、[TMPP]~-,阳离子取代链为长烷烃的季膦类和季胺类ILs具有更强的溶解CH_4的能力。特别是[P4444][TMPP]和[P(14)666][TMPP]对CH_4表现出优越的溶解性,可考虑用这2种ILs存储CH_4。至于两者能否用于浓缩CH_4,还需实验测试[P4444][TMPP]和[P(14)666][TMPP]溶解CO_2和N_2的情况,以及对溶解过程的影响。  相似文献   
382.
零价铁活化过硫酸钠降解2-萘磺酸   总被引:1,自引:1,他引:0       下载免费PDF全文
近几年来,基于SO-4·的新型高级氧化技术逐渐成为水处理领域的研究热点。利用零价铁活化过硫酸钠产生SO-4·对水溶液中2-萘磺酸开展了降解研究。考察了零价铁投加量、过硫酸钠浓度、温度、p H值、腐殖酸、富里酸、硫酸盐及2-萘磺酸初始浓度对2-萘磺酸降解效果的影响。结果表明:温度升高,酸性或中性环境下有利于2-萘磺酸的降解;零价铁投加量为0.1 g/L、过硫酸钠浓度为3.0 mmol/L时,2-萘磺酸的降解率高达96.8%;腐殖酸和富里酸的存在有利于2-萘磺酸降解,硫酸钠的存在会抑制2-萘磺酸降解。研究表明:采用零价铁活化过硫酸盐降解技术去除水溶液中2-萘磺酸具有广阔的应用前景。  相似文献   
383.
This study introduces a new and parsimonious classification of supervisor monitoring (observational monitoring and interactional monitoring) and examines the effects of these two monitoring styles on subordinate innovation. Guided by social exchange theory, we propose that the two monitoring styles influence subordinate job attitudes (trust and distrust in their supervisor), relationship quality (leader–member exchange), and work behaviors (feedback‐seeking behaviors), which, in turn, affect their innovation. The pilot study developed the scales for the two monitoring styles and tested their content validity among 189 undergraduate students. Using a sample of 385 subordinates, Study 1 assessed the construct validity of the two monitoring styles. In Study 2, the results of a survey of 388 supervisor–subordinate dyads show support for the proposed theoretical model. Specifically, observational monitoring and interactional monitoring were related to subordinates' trust and distrust in their supervisor. Trust and distrust in the supervisor, in turn, were related to the quality of the leader–member exchange, feedback‐seeking behaviors, and ultimately, supervisor‐rated innovation. These findings suggest that supervisors' monitoring styles have both positive and negative effects on their subordinates' innovation, which depends on the type of monitoring supervisors engage in. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
384.
PEM water electrolysis is one of the most efficient methods for the production of hydrogen because of produced high purity of the gases and environmentally friendly. In the present study, Phosphorus-doped Graphene (PG) was synthesized by thermal annealing of triphenylphosphine (TPP) and graphene oxide (GO). The PG supported palladium (Pd/PG) electrocatalysts were synthesized by chemical reduction method and used as the cathode for hydrogen evolution reaction (HER) electrode. Structural properties and electrochemical performances of the synthesized Pd/PG electrocatalyst were studied by FE-SEM, EDS, ICP, FT-IR, XRD, and Cyclic voltammetry (CV) methods, respectively. The membrane electrode assemblies (MEA’s) were fabricated using Pd/PG as cathode for HER electrode and RuO2 as anode for OER electrode. Also, their electrochemical performances along with the corresponding hydrogen yields were evaluated in single cell PEM water electrolyzer at various experimental conditions such as different current densities from 0.1 to 2.0 A cm?2 and temperatures (28–80°C). The synthesized Pd/PG electrocatalyst was observed a current density of 1 A cm?2 with 1.95 V at 80°C. Further, long-term stability studies were carried out continuously up to 2000 h which showed a reasonable stability. Hence, the synthesized Pd/PG can be used as an alternative to Pt-based electrocatalysts for the HER in PEM water electrolysis.  相似文献   
385.
Bauxite tailings are a major type of solid wastes generated in the flotation process. The waste by-products caused significant environmental impact. To lessen this hazardous effect from poisonous mine tailings, a feasible and cost-effective solution was conceived and implemented. Our approach focused on reutilization of the bauxite tailings by converting it to 4A zeolite for reuse in diverse applications. Three steps were involved in the bauxite conversion: wet-chemistry, alkali fusion, and crystallization to remove impurities and to prepare porous 4A zeolite. It was found that the cubic 4A zeolite was single phase, in high purity, with high crystallinity and well-defined structure. Importantly, the 4A zeolite displayed maximum calcium ion exchange capacity averaged at 296 mg CaCO3/g, comparable to commercially-available zeolite (310 mg CaCO3/g) exchange capacity. Base on the optimal synthesis condition, the reaction yield of zeolite 4A from bauxite tailings achieved to about 38.43%, hence, this study will provide a new paradigm for remediation of bauxite tailings, further mitigating the environmental and health care concerns, particularly in the mainland of PR China.  相似文献   
386.
Abstract:  Europe is one of the world's most densely populated continents and has a long history of human-dominated land- and seascapes. Europe is also at the forefront of developing and implementing multinational conservation efforts. In this contribution, we describe some top policy issues in Europe that need to be informed by high-quality conservation science. These include evaluation of the effectiveness of the Natura 2000 network of protected sites, implications of rapid economic and subsequent land-use change in Central and Eastern Europe, conservation of marine biodiversity and sustainability of fisheries, the effect of climate change on movement of species in highly fragmented landscapes, and attempts to assess the economic value of ecosystem services and biodiversity. Broad policy issues such as those identified are not easily amenable to scientific experiment. A key challenge at the science–policy interface is to identify the research questions underlying these problem areas so that conservation science can provide evidence to underpin future policy development .  相似文献   
387.
用弱碱性离子交换树脂分离2-萘磺酸的研究   总被引:3,自引:0,他引:3  
李长海  史鹏飞 《化工环保》2001,21(6):320-323
介绍了采用弱碱性离子交换树脂回收2-萘磺酸废水中的2-萘磺酸的试验研究。进行了pH、交换温度、共存阴离子等影响因素的条件试验及树脂再生试验,在较佳条件下,2-萘磺酸交换吸附率达98%以上,洗脱率接近100%。  相似文献   
388.
滤筒式除尘器的改进及在白云石生产中的应用   总被引:2,自引:0,他引:2  
介绍了利用改进滤筒、增加导流装置等一系列技术措施,提高滤筒式除尘器性能,使之应用于轻烧白云石除尘系统。实践表明,设备运行稳定,效果良好。  相似文献   
389.
A hypothesis is considered that the establishment and maintenance of mass exchange processes in the Paramecium bursariasymbiotic complex (infusorian–alga) depends on the presence of the third component—bacteria—whose role is underestimated but essential for completing the exchange cycle. The role of this component in the symbiotic cycle of Paramecium bursariais possible to reveal using special bactericidal preparations specifically inhibiting the bacteria involved in the metabolic cycle but having no effect on the functions of the host cell and the zoochlorella population. Experiments with various preparations of this type were performed, and the response to treatment was estimated from growth rates of the symbiotic complex and its components. This allowed identification of an antibiotic (rifampicin) that had no adverse influence on free-living zoochlorella and chlorella-free paramecia (the basic components of the symbiotic cycle) but drastically inhibited the growth of the P. bursariasymbiotic complex, which could be interpreted as evidence in favor of the hypothesis concerning the existence of the third symbiotic component.  相似文献   
390.
In this article, we describe a parallel agent-based model of spatial opinion diffusion that is driven by graphics processing units (GPUs). Modeling opinion exchange and diffusion across landscapes often involves the simulation of large numbers of geographically located individual decision-makers and a massive number of individual-level interactions. This simulation requires substantial computational power. GPU-enabled computing resources provide a massively parallel processing platform based on a fine-grained shared memory paradigm. This massively parallel processing platform holds considerable promise for meeting the computing requirement of agent-based models of spatial problems. In this article, we focus on the parallelization of an agent-based spatial opinion model using GPU technologies. We discussed key algorithms designed for parallel agent-based opinion modeling: including domain decomposition and mutual exclusion. Experiments conducted to examine computing performance show that GPUs provide a computationally efficient alternative to traditional parallel computing architectures and substantially accelerate agent-based models of large-scale opinion exchange among individual decision makers.  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