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   585篇
  免费   76篇
  国内免费   185篇
安全科学   127篇
废物处理   37篇
环保管理   67篇
综合类   384篇
基础理论   41篇
污染及防治   125篇
评价与监测   32篇
社会与环境   17篇
灾害及防治   16篇
  2024年   5篇
  2023年   18篇
  2022年   33篇
  2021年   35篇
  2020年   18篇
  2019年   23篇
  2018年   21篇
  2017年   25篇
  2016年   34篇
  2015年   30篇
  2014年   38篇
  2013年   71篇
  2012年   70篇
  2011年   53篇
  2010年   32篇
  2009年   31篇
  2008年   35篇
  2007年   37篇
  2006年   40篇
  2005年   26篇
  2004年   24篇
  2003年   29篇
  2002年   18篇
  2001年   25篇
  2000年   9篇
  1999年   10篇
  1998年   12篇
  1997年   16篇
  1996年   5篇
  1995年   8篇
  1994年   2篇
  1993年   1篇
  1992年   4篇
  1991年   2篇
  1986年   1篇
  1985年   1篇
  1982年   2篇
  1979年   1篇
  1974年   1篇
排序方式: 共有846条查询结果,搜索用时 15 毫秒
791.
土壤污染修复技术研究进展   总被引:5,自引:0,他引:5  
总结了当前针对污染土壤的物理化学、生物及联合修复技术研究进展,归纳了纳米材料、生物炭和表面活性剂等新兴修复材料的优缺点及应用情况。提出今后的研究方向为强化生物修复技术,开展联合修复技术、复合材料修复技术及土壤修复技术风险防范研究。  相似文献   
792.
烟火材料的自燃与对策   总被引:1,自引:0,他引:1  
从物质自燃现象的一般属性出发,通过对自燃加速曲线的分析,引伸出了烟火材料自燃特有的内涵。按照放热反应的不同形式对可自燃的烟火材料进行了分类。提出了发生自燃事故的统计规律以及防止事故的一些技术和管理措施。  相似文献   
793.
The thermal explosion problem of cumene hydroperoxide exothermic reaction which is used in chemical industries for production of some chemical materials is investigated. The analytical solutions of the problem to determine the margin between ignition and non-ignition systems are presented. The solution offers different analytical expressions which relate between the critical parameters for both steady and unsteady-states in different planes of solutions for different cases. The numerical solutions in different planes offer different trajectories of solution as sub-critical (non-ignition) and supercritical (ignition). Also from the numerical solution the relations between the critical parameters are presented. The critical behaviors from both analytical and numerical solutions are concise and pertained the same results.  相似文献   
794.
为合理选择公路运输危险品路线,保障运输安全,将用于求解静态路径规划问题的Diikstra标号法进行推广和改进,提出指标累积值标号法,运用该方法并依据危险品罐车运输事故统计数据,建立了时变条件下以路段泄漏事故率、路侧人口密度及路段运输费用为指标的危险品罐车公路运输路线选择模型.并给出待选路线对比原则.实例应用表明,该模型充分考虑了事故概率、事故后果及运输成本3大危险品运输路线选择影响因素,使用方便且受主观因素影响小,具有较好的实用性.  相似文献   
795.
为解决现有清除溢油技术存在的效率低、自动化程度低、成本高等问题,针对其无法适应海面油污清理的机械化、智能化的需求,自主研发了一种超疏水亲油材料,即泡沫金属基浮油收集材料,设计并制作了溢油回收装置,结合自主水面机器人平台,研制出溢油清除水面机器人系统,该系统具有自主持续性吸油、自主巡航、自动识别油污等功能。实验表明,该超疏水亲油材料吸油效果良好,效率高,且吸油材料能够循环利用。通过水面机器人模拟测试分析可知,该溢油清除水面机器人系统能够实现海面油污清除的智能化、自动化,且具有较好的发展前景和应用前景。  相似文献   
796.
沉水植物与2种不同辅料混合好氧堆肥   总被引:1,自引:0,他引:1  
沉水植物富含氮、磷和钾等营养元素,通过堆肥实现营养物质的回收和利用是沉水植物资源化的有效途径。但是沉水植物含水率高、碳氮比低,需要对其进行一定的优化才能实现更好的堆肥效果。本研究采用麦秸、树叶分别作为辅料和沉水植物进行混合好氧堆肥实验,沉水植物好氧堆肥作为控制组。通过测定温度、挥发分、耗氧速率、电导率、种子发芽率(GI)、总氮、总磷和总钾等以评价堆肥产品的腐熟度和养分。结果表明,沉水植物好氧堆肥具有一定可行性,堆肥产品总养分含量为6.01%,符合有机肥使用标准(NY525-2012)中对总养分的要求,具有较好腐熟度,但堆肥产品pH值为8.90,大于标准值8.50,氮素损失率为35.11%;通过分别添加麦秸、树叶与沉水植物混合堆肥,堆肥产品pH值分别为8.33和8.24,氮素损失率分别为20.25%和11.21%;由电导率、GI、碳氮比综合分析3组堆肥产品腐熟度从高到低顺序为沉水植物与树叶 > 沉水植物与麦秸 > 沉水植物。通过添加富碳辅料如麦秸、树叶与沉水植物混合堆肥可以提高堆肥产品腐熟度,减少氮素损失提高肥效。  相似文献   
797.
本文在分析SBR 工艺特点的基础上,从反应器本身及SBR 反应运行工序的设计两方面对处理难降解有机物新型SBR 反应器的发展作了论述。分析认为SBR 工艺将在中小型企业含难降解有机物工业废水处理中广泛应用。  相似文献   
798.
利用多元多相光催化氧化反应器 ,可更换不同氧化剂、光源、金属氧化物半导体催化膜、电子捕获器 ,进行化学氧化、光氧化、光化学氧化、光催化氧化和光化学催化氧化等 5种类型多种组合试验 ,处理水中难降解有机物效果明显。设备具有持久性、灵活性、捕电性、简易性 ,适用于科研、工程试验中 ,亦可作教学设备  相似文献   
799.
BACKGROUND, AIMS AND SCOPE: The building materials are recognised to be major contributors to indoor air contamination by volatile organic compounds (VOCs). The improvement of the quality of the environment within buildings is a topic of increasing research and public interest. Legislation in preparation by the European Commission may induce, in the near future, European Union Member States to solicit the industries of paints, varnishes and flooring materials for taking measures, in order to reduce the VOC emissions resulting from the use of their products. Therefore, product characterisation and information about the influence of environmental parameters on the VOC emissions are fundamental for providing the basic scientific information required to allow architects, engineers, builders, and building owners to provide a healthy environment for building occupants. On the other hand, the producers of coating building materials require this information to introduce technological alterations, when necessary, in order to improve the ecological quality of their products, and to make them more competitive. Studies of VOC emissions from wet materials, like paints and varnishes, have usually been conducted after applying the material on inert substrates, due to its non-adsorption and non-porosity properties. However, in real indoor environments, these materials are applied on substrates of a different nature. One aim of this work was to study, for the first time, the VOC emissions from a latex paint applied on concrete. The influence of the substrate (uncoated cork parquet, eucalyptus parquet without finishing and pine parquet with finishing) on the emissions of VOC from a water-based varnish was also studied. For comparison purposes, polyester film (an inert substrate) was used for both wet materials. METHODS: The specific emission rates of the major VOCs were monitored for the first 72 h of material exposure in the atmosphere of a standardized test chamber. The air samples were collected on Tenax TA and analysed using thermal desorption online with gas chromatography provided with both mass selective detection and flame ionisation detection. A double exponential model was applied to the VOC concentrations as a function of time to facilitate the interpretation of the results. RESULTS AND DISCUSSION: The varnish, which was introduced in the test chamber 23 h after the application of the last layer of material, emitted mainly glycolethers. Only primary VOCs were emitted, but their concentrations varied markedly with the nature of the substrate. The higher VOC concentrations were observed for the parquets of cork and eucalyptus, which indicated that they have a much higher porosity and, therefore, a higher power of VOC adsorption than the finished pine parquet (and polyester film). The paint was introduced in the chamber just after its application. Only primary VOCs were emitted (esters, phthalates, glycolethers and white spirit) but some compounds, like 2-(2-butoxyethoxy)ethanol and diethylphthalate, were only observed for paint/polyester, which suggested that they were irreversibly adsorbed by the paint/concrete. Compared with the inert substrate, the rate of VOC emissions was lower for concrete in the wet-stage (first hours after the paint application) but slightly higher later (dry-stage) as a consequence of desorption. CONCLUSIONS: As to varnish, the substrates without finishing, like cork and eucalyptus parquets, displayed a higher power of adsorption of VOCs than the pine parquet with finishing, probably because they have a higher porosity. As concerns paint, the total masses of VOCs emitted were lower for concrete than for polyester, indicating that concrete reduces the global VOC emissions from the latex paint. Concrete is seen to have a strong power of adsorption of VOCs. Some compounds, namely 2-(2-butoxyethoxy)ethanol, diethylphthalate and TEXANOL (this partially), were either irreversibly adsorbed by the concrete or desorbed very slowly (at undetected levels). A similar behaviour had not been reported for gypsum board, a paint substrate studied before. RECOMMENDATIONS AND OUTLOOK: The present data suggest that concrete may be a recommendable substrate for paint in an indoor environment. As the nature of the substrate conditions the rate and nature of VOC emissions from wet materials, it must be explicit when emissions from composite materials are reported, in order to allow comparisons and labelling of the product in terms of indoor air quality.  相似文献   
800.
合成了以N-甲基咪唑为配体,Cu为活性中心的络合金属多相催化剂Cu(Ⅰ)-NHC-SBA-15.通过1H-NMR、13C-NMR、有机元素分析和FTIR对各步合成反应产物结构经行了鉴定;用SEM、N2吸附脱附等方法对催化剂进行了表征;用ICP测定了催化剂Cu含量.对催化剂催化2,4-二甲氧基溴苯还原脱溴活性进行了测试.在反应时间为24 h,通过正交实验和单因素实验,考察了催化剂用量、反应温度、还原剂用量等因素对脱溴率的影响,并确定了最佳反应条件:催化剂用量为0.05 g、水合肼用量为2 mL、反应温度为80℃,脱溴效果较好,脱溴率达到98.5%.对催化剂重复使用进行了初步研究.对催化反应动力学进行了初步研究,结果表明,该多相催化反应是由表面反应速度控制,并符合一级动力学反应.对反应机理进行了初步探讨.  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