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281.
Thermal hazard in a batch process involving hydrogen peroxide 总被引:1,自引:0,他引:1
P. De Filippis C. Giavarini R. Silla 《Journal of Loss Prevention in the Process Industries》2002,15(6):449-453
Hydrogen peroxide is a versatile and interesting reagent for many industrial processes; nevertheless, it is very sensitive to impurities that can catalyze its decomposition, so that the desired reaction could be accompanied by undesired parallel and consecutive reactions. As an example, the butadiene free radical polymerization with hydrogen peroxide in the presence of an organic solvent was studied. Batch polymerization occurs in the liquid phase at about 120 °C. Because of the involved reactive compounds and the relatively high temperature, this is an intrinsically dangerous reaction. Therefore calorimetric data can give important information about safety and process optimization during the scale-up. The aim of this research project was to study the influence of impurities on the overall heat of reaction. The experiments were made in a high-pressure reaction calorimeter. The study has revealed that impurities do indeed affect the reaction course. Most importantly, the presence of carboxylic acids and/or ionic iron must be avoided and the recycle of unreacted reagents must be carefully controlled to minimize the build-up of these impurities. 相似文献
282.
本研究以磁性硅藻土为载体,负载纳米过氧化钙(CaO_2),制备了一种可高效吸附磷酸盐且可回收的复合材料(MDCP),并利用SEM、EDX-mapping、XRD、XDS和VSM等技术对MDCP的微观形貌、内部结构、晶体组成以及元素组成进行了表征.结果表明,MDCP表面成功负载了CaO_2,并具有良好的磁性. MDCP对水中磷酸盐的吸附数据符合Langmuir等温吸附模型,根据Langmuir模型确定当T=20℃时MDCP对水中磷酸盐的最大单位吸附容量为191. 84 mg·g~(-1).吸附等温线与吸附动力学的结果表明,MDCP对磷酸盐的吸附过程属于化学吸附. pH对MDCP吸附磷酸盐具有显著的影响,MDCP对磷酸盐的有效吸附pH范围为4~10,且MDCP对溶液pH具有调节效果,可使溶液pH保持在7~9的水平.当溶液共存Cl-、SO_4~(2-)、CO3_~(2-)、HCO_3~(2-)、F-和NO_3~-等阴离子时,MDCP对水中磷酸盐仍具有良好的选择吸附性.回收后的MDCP可用HCl溶液对其吸附的磷酸盐进行解吸,解吸后的MDCP再次负载CaO_2后对磷酸盐去除率仍可达到初次吸附量的70%. 相似文献
283.
为了探究基于纳米过氧化钙(CaO2)的类芬顿氧化技术(Modified Fenton,MF)修复污染地下水的可行性,本研究先对纳米CaO2制备方法进行改进,制备出有效含量高达88.35%的纳米CaO2粉末;其次,通过分析静态试验中反应体系的pH值、DO以及硝基苯浓度变化,探究纳米CaO2降解硝基苯的过程和影响因素,确定了硝基苯的降解动力学和最佳反应条件;通过掩蔽实验探究不同自由基的作用效力;最后进行一维模拟柱动态模拟,综合分析评估纳米CaO2去除硝基苯的机理和效果.结果表明:CaO2投加量、EDTA-Fe2+浓度与硝基苯初始物质的量浓度满足48:8:1时降解效果最佳,其降解曲线符合一级动力学曲线,且反应过程中起主要降解作用的自由基是·OH,但降解效果会受到HCO3-、SO42-、Ca2+、Mg2+等离子的影响;一维模拟柱的模拟结果表明,在存在适量铁的条件下,纳米CaO2可以作为过氧化氢缓释剂,通过类芬顿催化产生自由基降解污染物,这说明纳米CaO2在场地修复中具有较好的应用前景. 相似文献
284.
The maximum laminar burning velocity (LBV) of a fuel-air mixture is an important input parameter to vapor cloud explosion (VCE) blast load prediction methods. In particular, the LBV value has a significant impact on the predicted blast loads for high reactivity fuels with the propensity to undergo a deflagration-to-detonation transition (DDT). Published data are available for the maximum LBV of many pure fuel-air mixtures. However, little test data are available for mixtures of fuels, particularly for mixtures of fuels and inert species. Such mixtures are common in the petroleum refining and chemical processing industries. It is therefore of interest to be able to calculate the maximum LBV of a fuel/inert mixture based on the mixture composition and maximum LBV of each component.This paper presents measured test data for the maximum LBV of H2/inert and C2H4/inert mixtures, with both nitrogen and carbon dioxide as the inert species. The LBV values were determined using a constant-volume vessel and the pressure rise method. This paper also provides a comparison of the measured LBV values with simplified LBV prediction methods. 相似文献
285.
通过施加外加偏压把TiO2/Ti薄膜阳极产生的光生电子转移到阴极,并对其在阴极的电化学行为进行了研究.用水杨酸探针法对阴极溶液中产生的活性氧自由基进行了检测,探讨了pH值、恒电流值和连接类型等因素对阴极室溶液中对苯醌降解效果的影响.实验结果表明,在酸性条件下,转移至阴极的光生电子可将溶液中的溶解氧还原生成H2O2,再进而生成·OH;在pH值为2.0、恒电流为3.5mA和阳离子膜作为反应器双室连接类型的条件下,在60min内,阴极溶液中对苯醌的降解率可达到82.3%. 相似文献
286.
本研究模拟原位覆盖CaO2流失后状态,以修复后表层2cm底泥为研究对象,通过扫描电子显微镜(SEM)和X射线能谱仪(EDX)对底泥修复前后表面进行观察和元素分析,发现CaO2重塑明显改变了底泥结构,去除底泥表面附着的大部分有机物和铁锰氧化物,提高底泥颗粒孔隙率,增加底泥表面Ca2+含量;CaO2重塑使底泥内源磷更加稳定,TP含量减少约20%,潜在活性磷含量减少约30%,Ca-P和Res-P含量明显增加,同时厌氧环境下重塑底泥磷释放量明显小于原始底泥,表明CaO2重塑极大降低了底泥内源磷释放风险;Langmuir模型与Freundlich和Dubinin-Radushkevich模型相比,更适用于描述CaO2重塑底泥对水中磷酸盐的等温吸附行为,CaO2重塑明显提高底泥对水中磷酸盐的吸附能力,其最大磷吸附量由1.44 mg·g-1增加到20.91 mg·g-1,其对水中磷酸盐的吸附机制由化学吸附转变为物理化学吸附共同作用,此外准二级动力学模型可以较好地描述CaO2重塑底泥对水中磷酸盐的吸附动力学过程,且CaO2重塑显著提高底泥对水中的磷酸盐的吸附速率. 相似文献
287.
Sarah D. Lever Maria Papadaki 《Journal of Loss Prevention in the Process Industries》2005,18(4-6):392-396
When ortho-nitrated benzoic acids are chlorinated in xylene and acetonitrile, the product gases, HCl and SO2, dissolve in the solvent mixture. Previously measured solubilities [Lever, S. D., Papadaki, M. (2004a). o-Chlorination of 2-nitrobenzoic acid with thionly chloride in xylene and acetonitrile. Solubility study of hydrogen chloride and sulphur dioxide in xylene and acetonitrile, IChemE transactions part B. Process Safety and Environmental Protection. 48–60.] were compared to other published data and found to be in very good agreement. The heat of solution of SO2 in xylene was evaluated calorimetrically and compared to the value obtained from our previous experimental work. In our previous work [Lever, S. D., Papadaki, M. (2004b). Study of condition-dependent decomposition reactions—the thermal behaviour and decomposItion of 2-nitrobenzoyl chloride part_I. Journal of Hazardous Materials. 115; pp. 91–100], it was reported that the products of the decomposition are condition dependent. The current study showed that the decomposition is extensively promoted by the presence of HCl. This has important safety implications should the process operating temperature be reduced and HCl solution in the solvent mixture be increased. If a thermal runaway began in the increased availability of HCl, an undesirable escalation of the runaway could occur. 相似文献
288.
废铁屑—H2O2法处理炼油厂含酚废水 总被引:6,自引:0,他引:6
用废铁屑作催化剂,H2O2作氧化剂,对炼厂汽提后含硫废水进行了除酚试验研究,考察了初始PH、H2O2投加量、废铁屑投加量对酚去除率的影响。对含酚量为331.5mg/L的废水,将其初始PH调至7.2,30%H2O2的投加量为7.5mL/L,废铁屑的投加量为3-8g/L,经2h反应后,酚的脱除率可达99.9%。 相似文献
289.
由丁二烯过氧化物引发的爆炸事故已受到社会的关注和重视 ,国内外一些学者针对丁二烯过氧化物的危险特性进行了一些研究工作 ,并取得了一定进展。但由于丁二烯过氧化物本身合成与测试的复杂性和危险性 ,深入而系统地研究丁二烯过氧化物的危险性及其机理显得十分必要 ,同时将面临重重困难。 相似文献
290.