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   1332篇
  免费   167篇
  国内免费   443篇
安全科学   217篇
废物处理   37篇
环保管理   143篇
综合类   963篇
基础理论   189篇
污染及防治   160篇
评价与监测   108篇
社会与环境   82篇
灾害及防治   43篇
  2024年   10篇
  2023年   32篇
  2022年   85篇
  2021年   99篇
  2020年   86篇
  2019年   79篇
  2018年   63篇
  2017年   89篇
  2016年   60篇
  2015年   96篇
  2014年   72篇
  2013年   101篇
  2012年   106篇
  2011年   123篇
  2010年   121篇
  2009年   101篇
  2008年   101篇
  2007年   109篇
  2006年   88篇
  2005年   72篇
  2004年   53篇
  2003年   35篇
  2002年   41篇
  2001年   34篇
  2000年   25篇
  1999年   9篇
  1998年   7篇
  1997年   10篇
  1996年   8篇
  1995年   8篇
  1994年   2篇
  1993年   5篇
  1992年   7篇
  1990年   3篇
  1986年   1篇
  1983年   1篇
排序方式: 共有1942条查询结果,搜索用时 859 毫秒
861.
基于现阶段烟气汞的排放情况,介绍当前燃煤电站的几种烟气脱汞技术。主要是先将零价汞氧化为二价汞,再进行脱除。其中利用现有烟气控制设备,活性炭吸附及添加改性物质,有比较好的脱汞效率,电催化、光催化以及等离子体脱汞等新技术处于研发阶段,而烟气中多种污染物协同脱除有较好的应用前景。  相似文献   
862.
Sensitivity and severity parameters are critical for risk assessment and safety management of dust explosions. In this paper, to reveal the effects of material thermal characteristics on dust explosions parameters during monobasic alcohols dust explosions, three long chain monobasic alcohols, being solid at room temperature and similar in physical–chemical properties, were chosen to carry out experiments in different functional test apparatus according to the internationally accepted ASTM standards. As a result, it was found that the material thermal characteristics strongly affected these basic explosive parameters. On the one hand, for the sensitivity parameters, Minimum Ignition Temperature, Minimum Ignition Energy and Electrical Resistivity were the highest in the Eicosanol dust cloud, while Minimum Explosible Concentration in this cloud was the lowest. On the other hand, for severity parameters, Maximum Explosion Pressure in Eicosanol dust cloud always maintained the highest values as varying the dust concentrations. In contrast, Deflagration Index showed a complex trend.  相似文献   
863.
以锦鲤为试验对象,研究中药复方制剂对锦鲤的诱食活性及促生长的影响。实验分为4组,Ⅰ为对照组,饲喂基础饲料;Ⅱ、Ⅲ、Ⅳ为实验组,分别在基础饲料中添加150mL/kg、200mL/kg、250mL/kg的中药复方。喂食20d后的结果表明,各实验组均有较强的诱食活性(P<0.05),Ⅱ组效果最显著(P<0.01);Ⅱ组和Ⅲ组质量增加率和肥满度均显著高于对照组(P<0.05),Ⅱ组效果最显著(P<0.01),各实验组均能明显降低饲料系数(P<0.05)。  相似文献   
864.
Journal of Material Cycles and Waste Management - The massive generation of municipal solid waste (MSW) has become an essential social problem that not only damages the ecological environment but...  相似文献   
865.
乌海市是我国典型的煤焦化工业基地,大气污染物排放总量较大且近年来夏季O3污染问题逐渐突出,明确大气污染物排放特征,探究O3污染形成机制是客观认识其O3污染现状,科学制定污染控制措施的基础.基于"系数法"采用自下而上的方式构建了2018年乌海市高分辨率大气污染源排放清单(HEI-WH18),利用WRF-Chem对HEI-WH18的适用性和准确性进行评估,并结合模式诊断模块探究了乌海市夏季O3污染形成的原因.排放清单结果表明,2018年乌海市SO2、NOx、CO、PM10、PM2.5、VOCs、NH3、BC和OC的排放总量分别为65943、40934、172867、159771、47469、69191、1407、1491和1648 t ·a-1.与MEIC清单相比,利用HEI-WH18能更好地捕捉到O3及其前体物的排放变化规律和量级,适用于乌海市夏季O3的模拟及其来源分析研究.从O3及前体物的空间分布来看,乌海市海勃湾城区白天为O3高值区,3个工业园区无论白天和夜间均为O3低值区和NO2高值区,CO的空间分布特征与煤层及矸石堆自燃源一致.根据对O3污染过程的诊断分析,边界层中高层O3浓度的升高主要是平流输送和化学过程共同作用的结果,低层O3浓度的升高是垂直混合和平流输送导致的,化学过程在低层的贡献较为复杂,其正贡献起到了维持高O3浓度的作用,负贡献结合平流输送造成了O3污染的最终消散.  相似文献   
866.
双功能螯合剂在放射性药物的研究、合成、应用,特别是在生物分子的放射性标记方面发挥着极为重要的作用.本文采用简易方法合成了MAMA双功能螯合剂前体,N-(2"-对甲氧苄巯乙基)-2-[(2'-对甲氧苄巯乙基)氨基]乙酰胺,并通过Uv-vis、IR、1HNMR、MS以及元素分析等对其结构组成进行了确证;同时,利用Gaussian 03W程序对其进行了结构优化描述,并计算了相应的分子能量.此外,对制备得到的前体进行了稳定化处理,将其转化为盐酸盐形式,并用IR、1HNMR等进行了检验,确定了此处理是合理可行的.  相似文献   
867.
采用VAMP和密度泛函程序DMol3计算了沙林的生成热,并用VAMP-PM3/UHF半经验方法对沙林裂解的过渡态进行了优化计算,共发现9种过渡态,据此判断化学键断裂的难易顺序为P=O>P-F>P-O>C-O>P-C>C-C>C-H; C-H键断裂的活化能最小,可能与氢原子迁移到氧原子上有关.活化能小于相应的键解离能,计算结果能解释沙林的质谱数据.计算结果对使用低当量小型核武器破坏沙林等生化武器(核除剂)的可行性提供了能量上的参考,即试图通过计算得出有效的原位破坏沙林等生化战剂所需的最低能量,进而研究使用低当量小型核武器破坏沙林等生化武器的可行性.  相似文献   
868.
Although agonistic behavior in the male lobster cockroach, Nauphoeta cinerea, has been known for more than 40 years, this is the first study to directly collect and quantify the emitted pheromones. In the present study, emitted volatile pheromones were collected from each male pair for 60 min during the first encounter fight and identified and quantified by gas chromatography–mass spectrometry. The major compound collected was 3-hydroxy-2-butanone (3H-2B). The strength of the attack by the dominant male was classified into three categories from weakest (C) to strongest (A). Of the 92 pairs, eight (8.7%) showed no agonistic interactions, and the amount of 3H-2B collected was 121.8±37.7 ng/male pair. In the five pairs (5.4%) displaying attack strength C, the amount of 3H-2B collected was 689.6±273.7 ng/male pair, and the attack duration was 9.6±2.4 min. In the 53 pairs (57.6%) showing attack strength B, the corresponding values were 5396.2±449.0 ng/male pair and 22.7±1.6 min, while those for the 26 pairs (28.3%) showing attack strength A were 7910.4±1120.6 ng/male pair and 24.9±2.9 min. For both attack strengths A and B, a linear relationship was found between the amount of 3H-2B collected and attack duration, suggesting that the longer the duration of the attack, the more 3H-2B was emitted. In addition, the rate of 3H-2B emission for attack strength A was significantly higher than that for attack strength B. Using Vaseline-coating, we demonstrated that, in the first encounter fight, the 3H-2B was emitted by the dominant male.  相似文献   
869.
China is a large densely populated country undergoing rapid industrialization and is becoming one of the world's biggest consumers of natural resources. This circumstance provides a sharp contrast with other countries. As China is so significant in the global economy, studies of its eco-industrial development are very important. In this study we examined the state of eco-industrial development in China and have drawn conclusions from this analysis about some of the future prospects for sustainable development. In the analysis, we investigated the application of industrial ecology concepts by reference to several case studies. We have therefore described the current environmental situation in China, and have provided an overview of eco-industrial development and its implementation. Constraints to industrial sustainability in China have also been examined. We consider that eco-industrial development in China is in its infancy, and that closed loops involving chains and industrial symbiotic webs are the technological key and core of successful initiatives in the application of industrial ecology. In the case studies, we found that each system has different characteristics and management concerns. Our major conclusion is that even though China's Agenda 21 highlights the principles and sets the directions for eco-industrial development, these have not yet become essential ingredients in the country's industrial policy and practice for implementing Agenda 21.  相似文献   
870.
河北省小城镇发展中的问题和对策   总被引:3,自引:0,他引:3  
本文分析了河北省小城镇发展中存在的诸多制约因素 :阐述了城乡一体化 ,破除二元结构 ,构建有利于小城镇发展的社会环境的构想 ,并提出了关于改革城乡居民户籍管理制度、乡镇企业向镇区集中等一系列建议和措施  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