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171.
Adopting a principle of “check-accept for the first rank, inspection for the second rank”, this paper briefly discusses the rationale of the sampling inspection and the sampling inspection schemes to digital products in GIS. The OC curve is drawn to explain the deficiency of the percent sampling inspection. Meanwhile, the method of One Time Limiting Quality of count selection is presented as the inspection scheme for production departments while the method of One Time After-inspection Mean Percent Defective Upper Limit of count selection is for acceptance departments.  相似文献   
172.
Abstract

I argue that scientific disciplines are esteemed, supported, and patronized largely to the degree to which they are perceived as providing a “return” on invested societal resources. This “return” takes the form of scholarly products that help answer deep human questions or otherwise materially benefit members of the society whose resources they are. Such a view implies that disciplines exist in a “market” in which members compete for these limited resources by delivering products seen as valuable. In such a market, disciplinary relevance and survival are ultimately tied to decisions individual scholars practicing within the disciplines make about which research they pursue, the greater the perceived “return” the better for the long-term health of the discipline.  相似文献   
173.
Bezafibrate (BZF), a widely used lipid regulator, is a potential threat to ecosystems and human health in water, and the recent research showed that advanced oxidation processes (AOPs) are much more effective for BZF degradation. In this study, we investigated the photochemical decomposition of BZF in surface water and effluent from waste water treatment plants (WWTP) by UV/H2O2 process. The results showed that the UV/H2O2 process was a promising method to remove BZF at low concentration, generally at µg L?1 level. When initial concentrations reach 100 µg L?1 in the deionized water, >99.8% of BZF could be removed in 16 min under UV intensity of 61.4 µm cm?2, at the H2O2 concentration of 0.1 mg L?1, and neutral pH condition. Moreover, BZF degradation was inhibited in this process when humic acid (HA) and inorganic solution anions were added to the deionized water solutions, including chloride, nitrate, bicarbonate, and sulfate, significantly. In the surface water and effluent of WWTP, however, the removal efficiency of BZF was lower than that in the deionized water because of the interference of complex constituents in the surface water and effluent. Some main intermediates at the m/z range of 100–400 were observed by high performance LC‐MS (HPLC/MS) and a simple pathway of BZF degradation by UV/H2O2 was proposed.  相似文献   
174.
In this study the occurrence of diclofenac and sub‐products in effluent emerging from the University Hospital at the Federal University of Santa Maria was investigated. One metabolite was identified and, in aqueous solution, three degradation products. The quantification was conducted by means of HPLC‐DAD, and the determination of metabolite and degradation products by LC–ESI–MS/MS–QTrap. For the HPLC‐DAD method, a 70:30 mixture of methanol/sodium phosphate was used in isocratic mode. For the LC–ESI–MS/MS–QTrap determinations, a mobile phase, where phase A was an ammonium acetate solution 5 × 10?3 mol L?1, and phase B was methanol (5 × 10?3 mol L?1)/ammonium acetate (9:1, v/v), on gradient mode. The LDs for the HPLC and LC–MS/MS methods, respectively, were 2.5 and 0.02 µg L?1, the LQs, 8.3 and 0.05 µg L?1, and the linear range from 10 up to 2000 µg L?1 and 0.05 up to 10 µg L?1. As expected, the LC–ESI–MS/MS–QTrap method was more sensitive and less laborious. The metabolite 4′‐hydroxy‐diclofenac was identified. Photolysis was used for the degradation studies and three products of diclofenac were identified (m/z of 214, 286 and 303) in aqueous solution. These results notwithstanding, no degradation products of diclofenac were found in the hospital effluent.  相似文献   
175.
《Marine pollution bulletin》2014,78(1-2):196-200
Although contamination of the marine ecosystems by plastics is becoming recognised as a serious pollution problem, there are few studies that demonstrate the contribution made by freshwater catchments. Over a three month period from September to December 2012, at seven localities in the upper Thames estuary, 8490 submerged plastic items were intercepted in eel fyke nets anchored to the river bed. Whilst there were significant differences in the numbers of items at these locations, the majority were some type of plastic. Additionally in excess of 20% of the litter items were components of sanitary products. The most contaminated sites were in the vicinity of sewage treatment works. While floating litter is visible, this study also demonstrates that a large unseen volume of submerged plastic is flowing into the marine environment. It is therefore important that this sub-surface component is considered when assessing plastic pollution input into the sea.  相似文献   
176.
177.
一种基于卫星遥感和数值预报产品的雾预报方法   总被引:1,自引:0,他引:1       下载免费PDF全文
以气象卫星云图为基础, 应用云雾光谱特征和结构特征进行雾区的动态检测和提取;并利用地面自动气象站资料,采用诊断分析方法探讨雾区变化与多气象要素的关系。分析表明:雾区移动速度与地面风速有关,一定的相对湿度、地气温差和风速大小等要素阈值可以作为雾的排空条件。利用经修正的中尺度数值天气预报模式输出的气象要素产品,对卫星遥感雾区进行0~2 h的外延预报,进而建立了一个大雾短时临近预报业务平台,对2009年和2010年多雾季节的1—4月大雾过程应用统计结果表明,该方法对大雾短时临近预报具有一定的效果。  相似文献   
178.
2011年贵州两次降雪天气过程的多普勒雷达产品特征分析   总被引:1,自引:0,他引:1  
利用常规观测和新一代多普勒天气雷达回波资料对2011年1月17日至20日贵州省出现的两次降雪天气进行详细的特征分析。结果表明:贵州降雪回波强度一般〈30dBz,中心强度普遍在30-40dBz之间,反射率因子的分布梯度不大;但降雪过程中夹杂冰粒的时候,回波中心强度能达到50dBz。降雪回波的顶高一般在7km以下,其中顶高5-7km的情况占到60%左右,发展旺盛时回波顶高可达到8km以上。降雪回波径向速度的等值线比较密集,沿径向梯度变化大。“牛眼”状回波是降雪回波的一个典型特征,“牛眼”状回波正负速度中心值的大小与降雪量存在一定的正比关系。风廓线产品的近地面层风向对于预报降水类型有明显的指示意义,当风廓线产品上近地面1.5km高度的风向由东偏南转为东偏北时,地面冷平流取代暖平流,雨夹雪向纯雪转换,反之,暖平流取代冷平流,则是纯雪向雨夹雪转换,或者降雪减弱消失。  相似文献   
179.
机载LiDAR系统是一种主动式的对地观测系统,主要由中心控制单元、POS系统、激光扫描测距系统和数码相机组成。可以精确、快速地获取地面3维数据以及与其匹配的影像数据,从而生成高精度的4D产品。文中论述了LiDAR工作原理,介绍了机载LiDAR系统的组成,LiDAR数据的处理流程。最后,探讨了机载LiDAR系统在水利行业中的应用。  相似文献   
180.
浙江沿岸海产品中有机氯农药的残留水平   总被引:5,自引:0,他引:5  
1998年、2001年和2003年分别在浙江沿岸13个地区采集了53种海产品,采用GC-9A气相色谱仪对其进行了有机氯农药(HCH和DDT)残留量的检测,对不同类别海产品中HCH和DDT残留在浙江沿岸的分布状况以及有机氯农药异构组分分布的特点进行了分析,结果表明:(1)浙江沿岸海产品普遍受到HCH和DDT的污染,多数生物体内DDT的含量比HCH含量高,鱼类体内HCH含量高于软体动物和甲壳动物体内HCH的含量,而软体动物体内DDT的含量则高于鱼类和甲壳动物体内的DDT含量;(2)不同类别海产品(尤其是鱼类)体内HCH和DDT的残留量在浙江沿岸分布的差异较大,杭州湾、象山湾和乐清湾海产品体内HCH和DDT的残留量较高,而浙南的南麂和东部的普陀海产品体内HCH和DDT的残留量则较低;(3)1998年至2003年,浙江沿岸海产品中HCH含量呈微弱下降趋势,而DDT含量却呈现上升趋势(上升了107%);(4)2003年,浙江沿岸海产品中p,p′-DDT100%检出,其降解产物p,p′-DDD和p,p′-DDE也普遍检出,p,p′-DDT/ΣDDT明显升高,因此在浙江沿岸海域可能还存在DDT新的污染源;(5)浙江沿岸海产品中以p,p′-DDE的含量为最高,但与一些发达国家相比,其有机氯农药尚处于较低的水平。  相似文献   
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