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971.
为研究安全帽安全性与保护性问题,利用落锤冲击实验,对不同材质安全帽吸能率、冲击力峰值进行研究。结果表明:随冲击能量增加,安全帽受冲击力峰值呈指数倍增长,吸能率呈指数倍下降;ABS树脂与玻璃钢材质安全帽头模受冲击力峰值小于HDPE材质安全帽;当冲击能量大于60 J,HDPE材质安全帽丧失保护功能;ABS安全帽能够承受最大冲击力能量值为70 J,玻璃钢安全帽最大承载力高于ABS树脂安全帽。研究结果可为安全帽质量设计提供理论依据。  相似文献   
972.
为更系统地归纳安全氛围与安全绩效的关系,探究安全氛围、安全绩效及安全结果间的影响机制,采用Meta分析方法,通过2000—2020年54篇文献的55个独立研究样本进行定量综合分析,并进一步探讨安全氛围与安全绩效各维度间的关系,同时运用Meta二元回归探究潜在调节变量对2者间关系的调节作用。结果表明:安全氛围显著正向影响安全绩效,在高危行业中安全氛围对安全绩效影响更大;安全氛围与安全参与、安全遵守均显著正相关,且安全氛围对安全参与的影响强于对安全遵守的影响;安全氛围和安全绩效均与安全结果显著负相关,且安全绩效对安全结果的影响强于安全氛围对安全结果的影响。  相似文献   
973.
阐述环境执法存在的问题,对其现状、原因及进一步完善环境执法、提高依法行政水平提出了设想和建议。  相似文献   
974.
利用高效体积排阻色谱法测量了百花湖水中溶解有机质的分子量及其分布。结果表明百花湖水中溶解有机质(DOM)主要以分子量小于3500道尔顿(Da)的组分为主,其中重均(Mw)和数均(Mn)分子量分别界于2300~2500 Da和1900~2150 Da之间,说明其主要来源于降水对土壤有机物的淋滤和径流作用。根据色谱分析的结果,可以把溶解有机质的分子量分布分为四个组分:大分子量组分(MW〉3500 Da);中等偏大分子量组分(3500~2000 Da);中等分子量组分(2000~1000 Da)和小分子量组分(MW〈1000 Da)。由于生物活动和光降解作用以及有机物的分解作用,导致各分子量组分随深度的变化规律不同,其中分子量在3500~2000 Da之间的有机物的含量随深度的增大而增大,其余组分的含量随深度的增大而减少。计算所得的溶解有机质的Mw和Mn在表层较小,在中部随深度基本保持不变,到底部又变大。这种变化趋势与分子量组分的变化结果一致。  相似文献   
975.
In general, reproductive output in long-lived bird species increases in older compared to younger individuals. Therefore, experienced mates should be advantageous for first-time breeders. To examine requirements and consequences of experienced pair mates we investigated the first pair bonds of common terns, Sterna hirundo, recruiting to their natal colony. We found that male recruits were usually the same age as their mates, whereas female recruits were usually the younger member of the pair. In order to acquire experienced mates, it was necessary for males to arrive early in the year of recruitment. Mates with 2 or more years of breeding experience were only attainable by male recruits characterised by greater body mass and age. Female recruits arrived more than 1 week later than their experienced mates and significantly later in the season than male recruits paired with experienced females. In general, females first bred at a younger age than males, and neither the female recruits body mass nor their age was related to the level of experience of their first mate. These sex-specific differences in obtaining an experienced mate did not result in different levels of reproductive success between the sexes. Male and female recruits with mates with 2 or more years breeding experience benefited from having experienced mates: they had greater reproductive success. First-time breeders paired with mates with only 1 year of breeding experience did not differ from pairs where both members were breeding for the first time in terms of reproductive success, but clutches were larger. Our results illustrate not only different prerequisites for males and females, but also males need for experienced mates. Delayed male breeding (postponing breeding for another year), supposed to be a negative trait, and high body mass, supposed to be a trait of superior individual quality, can be combined in some individuals, improving reproductive success and showing that breeding common terns use a range of tactics to begin reproduction.Communicated by F. Trillmich  相似文献   
976.
《组织行为杂志》2017,38(6):895-916
Prior literature examining the antecedents of employee affect has largely ignored subtle affective influences in the workplace and their impact on employees' affective experiences and behaviors. A substantial body of evidence from basic psychology research suggests that individuals' affect can be influenced by minimal stimulus input. The primary objective of this research is to take an initial step towards understanding the “real‐world” impact of subtle affective stimuli in the workplace. Specifically, in a field experiment with a within‐subjects design, we collected data from 68 sales representatives and examined the effect of a subtle affective stimulus (i.e., a black‐and‐white picture of a woman smiling printed on the backdrop of paper–pencil surveys) on employees' affect, well‐being, and performance. Results showed that the smiling picture significantly enhanced participants' positive affect, which in turn influenced employees' extra‐role performance and emotional exhaustion. The smiling picture also indirectly influenced employees' in‐role performance and emotional exhaustion via negative affect. Theoretical and practical implications of these findings are discussed at the end of the paper. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   
977.
Objective: The objective of this study was to look for dose– and concentration–effect relationships in experimental studies on single-dose administration of morphine on traffic-relevant behavioral tests by a systematic literature review and possibly to see whether a dose/concentration could be defined below which few or no tests would be affected.

Methods: Searches for corresponding literature were conducted using MEDLINE, EMBASE, and PsycINFO, throughout March of 2016. The search strategy consisted of words colligated to cognitive and psychomotor functions of relevance to driving, in relation to morphine administration. The tests were arranged in main groups, and tests showing impairment were categorized by doses as well as calculated plasma concentrations.

Results: Fifteen studies were included in the review. Impairment after the administration of a single intravenously dose of morphine was found in some of the tests on reaction time, attention, and visual functions. No impairment was observed in tests on psychomotor skills and en-/decoding. Tests on reaction time appeared to be less sensitive to the morphine administration, whereas tests on visual functions and attention appeared to be the most sensitive to the morphine administration. Single-dose administration of morphine with dosages up to 5 mg appeared to cause very few effects on traffic-relevant performance tasks. At higher dosages, impairment was found on various tasks but with no clear dose–effect relationship. Plasma morphine concentrations less than 50 nmol/L are most probably accompanied by few effects on traffic-relevant performance tasks.

Conclusions: A plasma morphine concentration of 50 nmol/L (approximately 14.3 ng/mL) could represent an upper level, under which there is little accompanying road traffic risk. A single dose of 5 mg morphine IV and analgetic equivalence doses of fentanyl, hydromorphone, oxycodone, and oxymorphone are presented with the suggestion that few traffic-relevant effects will appear after such doses.  相似文献   

978.
通过使用不同浓度,不同类型的酸溶液,在不同条件下对堇青石载体进行预处理,考察了酸预处理前后载体本征性能的改变和对甲苯催化性能的影响,测试了其失重率,吸水率,上载率本征性能,并通过XRF,BET,SEM等手段进行表征测试分析.结果发现,通过使用20% HCl对堇青石载体进行加热处理3h,可获得最优性能的堇青石载体.吸水率较处理前可提升48.0%以上,活性组分上载率可达14.5%,皮尔逊检验表明吸水率与上载率存在中度正相关的相关性.通过对甲苯催化活性测试,其结果表明,通过酸预处理,堇青石载体比表面积提升10倍以上,由其制得的整体式催化剂催化降解甲苯的T10T90分别为142和200℃.  相似文献   
979.
本研究采用电化学测试和亚甲基蓝(MB)模拟废水处理两种手段评估了填充床电极反应器电催化氧化有机污染物的电极性能.循环伏安(CV)和电化学阻抗谱(EIS)拟合结果表明,填充床体系的电极面积是PbO2/Ti阳极面积的1.54倍(即床层拓展系数l为0.54),PbO2/Ti阳极(γ)和活性炭复极化粒子电极(β)用于MB氧化的有效电流占比分别为0.63、0.34;采用废水处理结果拟合所得的λγ+β为0.54和0.99,所得数值与前者相符,两种方式得以相互验证.对体系能耗和电流效率的回归分析及F检验结果证明了所构建评估策略的准确性,可为填充床体系电极性能评估提供理论与方法支撑.  相似文献   
980.
为研究危险废物填埋场环境下防渗系统HDPE膜(高密度聚乙烯膜)材料老化规律及其对渗滤液产生、渗漏和区域地下水环境的影响,通过HDPE膜缺陷现场检测及室内老化性能测试,获取了HDPE膜初始缺陷特征参数(漏洞密度)和缺陷演化特征参数(老化起始时间和半衰期),并以上述参数作为输入,综合运用HELP模型(填埋场水文过程评估模型)与Landsim模型(填埋场地下水污染风险模拟模型)对HDPE膜老化条件下的渗滤液产生、渗漏和地下水污染过程进行模拟预测.结果表明:①现场条件下HDPE膜在第2年开始老化,第8年达到半衰期.②HDPE膜老化导致漏洞数量和渗透系数增加,进而导致渗滤液渗漏量增加,地下水污染风险逐渐增加.短期(0~5 a)内,地下水超标概率为0,污染风险较小;中期(5~10 a)内,距离填埋场200 m内污染超标概率污染≥ 80%,污染风险较大,但400 m外的污染概率为0,污染风险较小;就长期(>10 a)而言,距离填埋场1 000 m处,污染超标概率达100%,地下水污染风险极大.填埋场现场条件下,防渗材料劣化及老化过程较实验室条件更为迅速,导致渗滤液长期渗漏、地下水污染风险加剧,因此建议加强填埋场设计和运行中HDPE膜抗老化研究,保障危险废物填埋场长期安全运行.   相似文献   
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