流动注射分析仪同时测定水样中总氮和总磷

为同时、快速测定水样中总氮和总磷,以合适的消解液消解水样,可实现同时测定总氮和总磷。基于此方法,流动分析仪同时测定总氮总磷快速,准确,呈良好线性关系,线性相关系数为0. 9979。对河流水、湖泊水等实际水样进行了应用分析,并对每个水样重复测试五次,其标准偏差在1%-3%之间,总氮和总磷的检出限均为0.02mg/L,总氮分析加标回收率为97%-106%,总磷分析加标回收率为-,结果表明流动注射分析仪应用于同时测定水样中总氮和总磷可得到广泛的应用。     

测定水中总氮时空白值影响因素的探讨

碱性过硫酸钾消解紫外分光光度法(HJ 636-2012)是目前水中总氮的主要检测方法。但检测过程中空白实验的吸光度值经常存在偏高的现象,致使测定的准确度和精密度差,直接影响测定结果。如何保证分析样品的精密度和准确度,成为测定过程中的关键之一。文章从环境影响、器皿影响、试剂影响等方面进行探讨,提出降低空白试验值的措施。     

高氯水样中COD分析方法比对研究

监测分析水样中COD的浓度,其最主要的干扰是氯离子的含量。本文对氯离子含量为500mg/l、1000mg/l的溶液,用于配制明码标液进行测定,分别用国标法:重铬酸盐法GB11914-89、行业标准:快速消解分光光度法HJ/T399-2007,"兰州某环保科技有限公司"的产品D试剂E试剂、D试剂Eg试剂的四种方法对其进行测定。     

替米考星溶液的紫外分光光度法测定

建立了紫外分光光度法测定替米考星溶液含量的方法。以0.01mol/L的盐酸为溶剂,测定波长为291nm,通过专属性试验、准确度试验、线性关系考察、精密度试验等方法学研究,建立了紫外分光光度法测定替米考星的方法。替米考星测定的线性方程为A=0.026 7ρ+0.005 9,r=0.999 9,线性范围为8～48μg/mL。准确度试验(n=9)平均回收率为100.6%,RSD值为0.5%。以紫外分光光度法测定替米考星溶液的含量,方法准确、简单易行,是适合快速测定替米考星含量的方法。     

高氯废水中低化学需氧量的快速检测研究

在高氯废水低化学需氧量的检测中,常用的检测方法有微波消解法、快速消解分光光度法与氯气校正法等。文章将快速消解分光光度法做为研究对象,对其进行改进处理,进一步提高高氯废水中低化学需氧量的检测速率与检测精度,为工业废水的测定提供更高效的方法。     

紫外分光光度法测定乙二醛溶液中乙二醛的含量

利用醛基与羟胺在酸性条件下的成肟反应产物乙二醛二肟对紫外光的吸收特性,用紫外分光光度法测定乙二醛的含量。结果表明,乙二醛溶液浓度在8.4×10-6~7.2×10-5mol/L范围内符合比耳定律,得出了回归方程,平均回收率为101.1%(n=8),RSD为0.75%。该方法可用于乙醛硝酸氧化法制备乙二醛中乙二醛含量的测定。     

头孢噻呋钠的紫外分光光度法测定

用紫外分光光度法测定头孢噻呋钠的质量浓度,以水为溶剂,在293nm波长处测定吸光度,头孢噻呋钠在7.5~17.5μg/mL范围内吸光度与质量浓度呈良好的线性关系,A=0.04833ρ-0.001800,r=0.9999(n=5)。本法适用于生产过程快速分析。     

微波消解-ICP法测定纺织品中十种微量元素含量

采用微波消解纺织品,其试液用电感耦合等离子体发射光谱仪（ICP- AES）法同时测定样品中As、Ba、Cd、Co、Cr、Cu、Ni、Pb、Sb、Se等10种微量元素。将微波消解条件、仪器分析条件进行了优化,确定了最佳测定条件。结果表明,该检测方法的检出限为0.04-0.068μg/L,回收率可以达到84%-106%。该法具有准确、快速、简便的特点,应用于纺织品中微量元素的测定,结果满意。     

浅谈水质总氮测定中不同过硫酸钾对空白值影响

碱性过硫酸钾消解紫外分光光度法测定总氮时,经常会出现空白吸光值偏高的情况。通过一系列对比试验,发现不同的过硫酸钾是是测定总氮空白值偏高的关键因素。     

紫外一可见分光光度法测定氧氟沙星片的含量

采用紫外-可见分光光度法测定氧氟沙星片的含量,用0.1 mol/L盐酸为溶剂,294 nm作为测定波长,质量浓度为2～12 mg/L时,吸光度与质量浓度呈线性关系,此方法的平均回收率为99.5％,RSD值为0.3％.该法操作简单、快速,结果准确.     

增强Linux系统安全性的措施

L inux系统的安全取决于系统管理员如何来管理它。本文探讨了一系列可以增强安全性的技巧与策略 ,包括 :系统安装原则、BIOS安全、口令安全策略、设计帐户自动注销功能、文件系统和日志安全策略、使用 SSH及 TCP-WRAPPERS,隐藏系统信息、删除所有特殊帐户、关闭控制台程序、限制系统中的 SUID/ SGID程序等。本文最后向 L inux系统管理员提出了一些安全管理方面的建议     

Comparing FTTH access networks based on P2P and PMP fibre topologies

There is an ongoing discussion in the market which Next Generation Access (NGA) architecture best suits future needs and which investment and cost differences exist. The discussion can be subsumed as P2P vs. GPON, which is somewhat misleading as this article reveals. The discussion is driven by the fact that the high capital cost and the long asset life time of fibre mean that the technology choices made today will dominate the opportunities for telecommunication business of all market players, incumbents, competitors, content providers and business and residential users for many years in the future.The paper analyzes the cost and other differences between Fibre-to-the-Home (FTTH) access network architectures and their related different wholesale approaches by using the well-known and understood steady state approach applied in other NGA analyses in the past. In addition to the steady state analysis a dynamic cost evaluation is included taking into account the different investment behaviour of the FTTH architectures over time. The results describe investment and cost differences between architectures, incumbents and wholesale based competitive operators. The analysis has been performed for different geotypes (clusters) of decreasing population density in a representative European settlement structure.     

CIS与现代企业管理美学

概括性介绍了 ＣＩＳ（Ｃｏｒｐｏｒａｔｅ Ｉｄｅｎｔｉｔｙ Ｓｙｓｔｅｍ）的三大基本组成，并阐述了它与现代企业管理密不可分的相互联系及所处的举足轻重的地位，指出导入ＣＩＳ是现代企业谋求发展的重要手段。     

Divergent patterns of engagement in Internet standardization: Japan,Korea and China

This article analyzes the engagement of Japanese, Korean and Chinese participants in the development of Internet standards at IETF on the basis of four quantitative metrics: attendance, patenting, authorship and leadership. The results are strikingly divergent. Japanese involvement in Internet standardization began early and Japan was, for many years, second only to the U.S. in terms of IETF participation. Though Japanese participation has declined since the early 2000s, Japan remains a major contributor to IETF standardization. Korean involvement in IETF has always been significant, but below the levels of Japan and major European countries. Korean participation in IETF has also declined over the past decade, and has been dominated by one firm, Samsung. Though meaningful Chinese involvement in IETF did not begin until the mid-2000s, it has rapidly expanded in recent years. Today, China is a major player in numerous areas of Internet standardization in terms of three metrics (participation, patenting and leadership), and is rapidly gaining in terms of document authorship as well. Most of China׳s recent IETF involvement can be attributed to Huawei, though other Chinese firms have recently begun to increase their participation in the organization. Thus, contrary to some views that China׳s engagement with standardization is primarily one of indigenous innovation and “catching up”, China׳s experience with IETF demonstrates deliberate and effective engagement with a major Western standards-development organization on its own terms.     

快速成形技术的应用及热点分析

基于快速成形技术的原理,展示了快速成形技术在快速模具制造、金属零件直接成形、反求工程等领域的广泛应用,总结了快速成形制造技术研究的热点,即研发新材料和新设备、提高成形精度、建立RPM的反求工程系统、建立成形技术的统一标准和扩大成形技术的应用领域。     

Whose Image is it Anyway?: Some Considerations of the Curricular Importance of Subject Image in Secondary School Design and Technology Education

This paper explores the idea that a sense of school subject image is a necessary feature of curriculum management and a potent force for change. The discussion centres on the view that all school subjects have an image and that if those intimately involved with the subject do not control the image then someone else does! In such circumstances the image is the product of past encounters and old euphemisms and is unlikely to hold the changed realities.The UK developments in Design and Technology education (the term Design and Technology is used to denote the school subject defined under this heading by the UK National Curriculum, 1995) have created something of an image problem which has interesting international parallels. Some of these problems are due to clearly discernible internal tensions and an ambiguous relationship with other subject areas.Through greater attention to subject image internal controversies might be acknowledged and resolved, relationships with other subject areas can be more meaningfully understood and practitioners can be helped to make sense of curriculum change.     

Indigenous peoples’ nutrition transition in a right to food perspective

In indigenous communities the nutrition transition characterized by a rapid westernization of diet and lifestyle is associated with rising prevalence of chronic disease. Field work and literature reviews from two different policy environments, Argentina (Jujuy) and Canada (Nunavut), identified factors that add to indigenous peoples’ disease risk. The analytical framework was the emerging human right to adequate food approach to policies and programmes. Indigenous peoples’ chronic disease risk tends to increase as a result of government policies that infringe on indigenous peoples’ livelihoods and territories, undermining their economic system, values and solidarity networks. Policies intended to increase food security, including food aid, may also fuel the nutrition transition. There is a need to explore further the connection between well-intended policies towards indigenous peoples and the development of chronic diseases, and to broaden the understanding of the role that different forms of discrimination play in the westernization of their lifestyles, values and food habits. Food policies that take due account of indigenous peoples’ human rights, including their right to enjoy their culture, may counteract the growth of chronic disease in these communities.     

Diffusion and usage of public e-services in Europe: An assessment of country level indicators and drivers

We analyze the state of the art of indicators on e-government, e-health, e-procurement and e-participation. We survey the main methodological properties of these indicators, and highlight their heuristic potential. Further, we address empirically the issue of the explanation of the availability scores, i.e. how the supply of the various e-services in each country is affected by political, institutional and socio-economic differences, and is followed by actual usage. The econometric analysis uncovers the importance of broadband penetration and higher education as drivers for most of the types of e-services and users (citizens and businesses). Moreover, a corruption-free and agile public sector proves to be an important pre-condition for more effective supply and usage. Despite data limitations and the complexity of the underlying diffusion phenomena, our study is the first truly longitudinal contribution aimed at disentangling the common drivers of such an important phenomenon – the e-services availability and usage across European countries. As such, this work appears useful to inform the policy debate and practice, in a phase characterized by a prospective reorientation of the public e-services provision and policy agenda.     

一种高精度的频率标准比对系统

频率标准源可以提供精确的标准频率,在测定频率标准源的各项性能指标时,要求测试系统必须具有很高的比对精度。所设计的频率标准比对系统采取多级倍频 混频方式使频率偏差逐级扩大后再测量,从而避免了直接进行高次倍频的困难,提高了测量精度,可以对高精度的频率标准的准确度、长短期频率稳定度进行快速测量,是一种高精度时畴参数测量系统。     

HSE走进中国石油

企业管理水平的好坏直接影响着企业的经济效益,运用HSE管理能提高企业管理水平,HSE管理模式将健康,安全,环境三者视为一个有机的整体。HSE管理认为人的安全是第一位的,人是创造财富的原动力,是企业的最大财产,HSE管理体系强调的是“蝴蝶效应”。