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121.
122.
Introduction: Rear-end crashes are one of the most frequent crash types in China, leading to significant economic and societal losses. The development of active safety systems – such as Automatic Emergency Braking System (AEBS) – could avoid or mitigate the consequences of these crashes in Chinese traffic situations. However, a clear understanding of the crash causation mechanisms is necessary for the design of these systems. Method: Manually coded variables were extracted from a naturalistic driving study conducted with commercial vehicles in Shanghai. Quantitative analyses of rear-end crashes and near crashes (CNC) were conducted to assess the prevalence, duration, and location of drivers’ off-path glances, the influence of lead vehicle brake lights on drivers’ last off-path glance, and driver brake onset, and the influence of off-path glances and kinematic criticality on drivers’ response to conflicts. Results: The results indicate that the Chinese truck drivers in our study rarely engage in distracting activities involving a phone or other handheld objects while driving. Instead, they direct their off-path glances mainly toward the mirrors, and the duration of off-path glances leading to critical situations are shorter compared to earlier analyses performed in Western countries. The drivers also often keep small margins. Conclusions: Overall, the combination of short time headway with off-path glances directed toward the mirror originates visual mismatches which, associated to a rapid change in the kinematic situation, cause the occurrence of rear-end CNC. When drivers look back toward the road after an off-path glance, a fast response seems to be triggered by lower values of looming compared to previous studies, possibly because of the short time headways. Practical Application: The results have practical implications for the development of driver models, for the design of active safety systems and automated driving, and for the design of campaigns promoting safe driving. 相似文献
123.
试验了水样预处理过程中所加氢氧化铝悬浮液的数量,以加1ml,并作了以活性炭代替树酯的试验,结果表明对测定结果的精密度和准确度均无影响。简化了操作手续,节省了时间。 相似文献
124.
研究了ECR-CTMAB体系测定土壤中活性铝的流动注射分析。结果表明,该方法具有快速、灵敏的特点,进样频率为60个样/时,检出限为0.05μg/ml。用不同提取液提取各地区土壤中活性铝并进行了测定。 相似文献
125.
A new coal pillars design method in order to enhance safety of the retreat mining in room and pillar mines 总被引:1,自引:0,他引:1
Most of the proposed methods for coal pillar design determine pillar dimensions using pillar load estimation only through the tributary area theory. Designing pillar based on these methods is not appropriate in room and pillar mines with pillar recovery because retreat mining and gob creation generate abutment loads. Neglecting abutment loads in design stage may lead to pillar failure and destructive effects during retreat mining. Thus proper pillar design has a remarkable effect on mining safety. In this paper, a step-by-step method is presented to design pillars with square shape in room and pillar mines with regard to existing pillars in the active mining zone (AMZ) and estimating abutment loads according to experimental equations. A decrease in pillar failure risk during retreat mining is the most significant benefit of this method. This method has been applied to determine optimum pillar dimensions in the main panel of Tabas Central Mine (TCM), located in the mid-eastern part of Iran. Obtained results show the abutment loads account for 27% of the total loads applied on pillars in AMZ in this panel. Pillar width, based on this method, is also obtained 11.6 m. 相似文献
126.
变光焊接护目镜光电响应特性研究 总被引:2,自引:1,他引:1
为促进变光焊接护目镜新技术新产品的应用和发展 ,为制定该产品专业标准提供依据 ,通过对焊接弧光特性、可见光特性、焊工盲目引弧过程、焊工闪光盲、变光护目镜响应时间和保持时间等的分析和研究 ,提出了变光焊接护目镜响应时间和保持时间应该根据焊工引弧时眼睛最大允许照射量和允许闪光盲时间来确定 ,并进一步提出了变光焊接护目镜响应时间和保持时间的定义、指标值 ,以及测试系统设计要求 相似文献
127.
基于紫外辐照/硼氢化钾/亚硫酸氢钠(UV/KBH4/NaHSO)3体系下对活性艳红X-3B进行还原脱色反应,重点探讨了该体系下还原降解活性艳红X-3B的反应机理,考察了硼氢化钾和亚硫酸氢钠的摩尔比(B/S)、辐射光强对其反应机理的影响。结果发现,UV/KBH4/NaHSO3处理染液具有明显协同作用,初步推测光助硼氢化钾和亚硫酸氢钠还原活性艳红X-3B的脱色反应是SO2-参与的自由基反应;脱色反应的B/S最佳摩尔比为1:30;增加辐射光的强度对染液的还原脱色反应过程具有明显的促进作用。 相似文献
128.
Series of Fe/Cu-SSZ-13 catalysts with different Fe loading content were synthesized by simple one-pot strategy. The obtained catalysts were subjected to selective catalytic reduction (SCR) of NOx with NH3 and were characterized by various techniques. The results show that Fe0.63/Cu1.50-SSZ-13 catalyst with proper Fe content exhibits excellent catalytic activity with widest operation temperature window from 160 to 580°C, excellent hydrothermal stability as well as good resistance to sulfur poisoning when compared with Cu-SSZ-13, signifying its great potential for practical applications. Further characterizations reveal that the synthesized Fe/Cu-SSZ-13 catalysts present typical chabazite (CHA) structure with good crystallinity, while isolated Cu2+ and monomeric Fe3+ are revealed as the predominant copper and iron species. At low temperatures, isolated Cu2+ species act as primary active sites for SCR reaction, while monomeric Fe3+ species provide sufficient active sites for sustain the SCR activity at high temperature. Moreover, Fe over doping would lead to the damage of zeolite structure, destruction of isolated Cu2+ site, as well as the formation of highly oxidizing Fe2O3, thus causing deterioration of catalytic performances. 相似文献
129.
Active moss biomonitoring of trace elements with Sphagnum girgensohnii moss bags in relation to atmospheric bulk deposition in Belgrade, Serbia 总被引:1,自引:0,他引:1
Anicić M Tasić M Frontasyeva MV Tomasević M Rajsić S Mijić Z Popović A 《Environmental pollution (Barking, Essex : 1987)》2009,157(2):673-679
Active biomonitoring with wet and dry moss bags was used to examine trace element atmospheric deposition in the urban area of Belgrade. The element accumulation capability of Sphagnum girgensohnii Russow was tested in relation to atmospheric bulk deposition. Moss bags were mounted for five 3-month periods (July 2005-October 2006) at three representative urban sites. For the same period monthly bulk atmospheric deposition samples were collected. The concentrations of Al, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, and Pb were determined by instrumental neutron activation analyses and atomic absorption spectrometry. Significant accumulation of most elements occurred in the exposed moss bags compared with the initial moss content. High correlations between the elements in moss and bulk deposits were found for V, Cu, As, and Ni. The enrichment factors of the elements for both types of monitor followed the same pattern at the corresponding sites. 相似文献
130.