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61.
Sodium is the main cooling medium in the circuit of fourth-generation nuclear reactors, and its leakage constitutes a severe fire hazard because of its high chemical activity. In this study, expandable graphite (EG), which is a traditional sodium fire-extinguishing agent, was modified with zinc borate (ZB) as an intercalator, and the modified EGZB was characterized. Moreover, the effectiveness of the modified EGZB in extinguishing sodium fires was tested using a self-developed fire-extinguishing experimental device. This study's results indicated that EG, EGZB had a smaller particle size, higher thermal stability, higher fire-extinguishing speed, and lower powder mass consumption than EG. During the fire-extinguishing process, ZnO decomposed by ZB captured free radicals and inhibited the combustion reaction. Furthermore, B2O3 was adsorbed on the surface of the EG layer, which strengthened covering and asphyxiation. The findings of this study provide crucial information for effectively controlling fires caused by active metals and metallo-organic compounds. 相似文献
62.
对焙烧炉筒体结构进行有限元建模仿真,考虑热应力、压力和重力对筒体结构受力的影响,计算了焙烧炉关键部位的蠕变疲劳寿命,同时探究进气温度、保温层及对流系数等参数的影响。结果表明:热应力是影响结构强度的关键因素;焙烧炉筒体在许用蠕变变形量为5%的情况下,其使用寿命超过设计寿命;在筒体加热过渡段铺设保温层,降低与外界空气对流和提高进气温度,有利于降低筒体应力。 相似文献
63.
目的 系统研究前驱体聚合反应时间对PI膜及其碳化、石墨化后薄膜结构和性能的影响规律。方法 通过调整聚合合成聚酰胺酸(PAA)溶液过程中的反应时间,制备石墨膜前驱体聚酰亚胺(PI)原膜,将不同工艺条件下制得的PI膜进行碳化、石墨化处理,得到高导热率石墨膜。利用扫描电镜、红外光谱、拉曼光谱仪和LFA激光闪射仪对制备的PI膜、碳化膜及石墨膜的微观结构和热导率进行检测。结果 随聚合反应时间的延长,PI膜酰亚胺化程度和石墨膜的石墨化程度及导热性能先增高、后降低。反应时间为3 h时,制得的石墨膜结构致密,石墨片层取向性好,导热性能最好,热导率可达765.2 W/(m.K)。结论 PI膜前驱体聚合反应时间显著影响PI膜酰亚胺化的程度和有序度,进而影响石墨膜的定向性和导热性能。 相似文献
64.
某钢铁企业高炉炼铁车间的出铁场在生产过程中产生大量高浓度的烟尘,对厂区的大气环境及周边的环境造成严重污染,同时直接危害了职工的身体健康。通过对整个出铁场除尘工艺系统及通风状况的分析及实际应用情况,总结出了适合该场合的系统除尘方案。 相似文献
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67.
通过单因子实验考察了无硫膨胀石墨制备过程中氧化剂及插层剂用量、氧化反应及插层反应时间、氧化反应及插层反应温度对无硫膨胀石墨膨胀体积的影响。通过正交实验确定了制备无硫膨胀石墨的最优条件是:石墨(g)∶浓硝酸(mL)∶30%H2O2(mL)∶乙酸酐(mL)=1∶2.25∶0.25∶0.6,在30℃条件下氧化反应60 min,加入插层剂后在60℃条件下插层反应90 min,此条件无硫膨胀石墨的膨胀体积达317 mL/g使用XPS、FT-IR、XRD和SEM对无硫膨胀石墨进行了表征并对其吸油性能和再生性能进行了研究。结果表明,所制备无硫膨胀石墨对原油和柴油的最大吸附量分别为66.3 g/g和62.7 g/g。吸附原油后的无硫膨胀石墨抽滤再生后首次再生率为49.1%,原油的回收率为64.5%。 相似文献
68.
石墨炉法测定铅的基体改进剂的选择 总被引:9,自引:0,他引:9
通过一系列实验,选择了石墨炉法测定铅的最佳基体改进剂,并确定了使用该基体改进剂的最佳灰化温度和原子化温度。 相似文献
69.
Estimation and characterization of PCDD/Fs and dioxin-like PCBs from Chinese iron foundries 总被引:5,自引:0,他引:5
The iron foundry industry is considered to be a potential source of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). This study investigated the emission factors and total emission amounts of PCDD/Fs and dioxin-like polychlorinated biphenyls (DL-PCBs) from iron foundries in China. The concentrations and the World Health Organization toxicity equivalents (WHO-TEQs) are presented and the congener profiles are discussed in this paper.In the present work, 26 fly ash samples were collected and tested to quantify the PCDD/Fs and DL-PCBs generated by 14 plants of different scales, and five stack gas samples were collected from two (named as EFG and LFG) of those plants. The emission levels of PCDD/Fs and DL-PCBs indicated that hot-air cupolas had lower emissions than cold-air cupolas. When iron ore lump and sinter were used as raw material, the emission factors were about 250 ng TEQ t−1 of product. However, if the raw material was scrap, the emission factors varied owing to the different contents of organic materials in the raw materials. It was found that the mean WHO-TEQ values of PCDD/Fs and DL-PCBs were 144 and 34.2 pg Nm−3 in stack gas and 20.0 and 1.58 pg g−1 in fly ash. In multiple tests, it was estimated that the mean emission factors of PCDD/Fs and DL-PCBs were 365 and 10.9 ng WHO-TEQ t−1 released to residue and 2719 and 555 ng TEQ t−1 released to air. The total emission amounts of PCDD/Fs and DL-PCBs from Chinese iron foundries with cupola furnaces released to residue and air were 16.8 and 146 g WHO-TEQ in 2008, respectively. 相似文献
70.