高粘度PA降粘机理及高强PA6综丝的研制

对不同降粘剂的降粘机理进行了初步探讨,并纺制了一些综丝样品,与常规综丝做了比较。结果表明,实验丝强度比常规丝强度约高35％,大分子链取向也明显高于常规丝,由此可见,在合适的工艺条件下,通过本实验方法可以得到理想的高强度锦纶综丝。     

β-内酰胺类抗生素氨曲南化学合成的研究进展

文章通过头孢他啶侧链活性酯和(3S-反式)-3-氨基-4-甲基-2-氧代-1-氮杂环丁烷磺酸为主要原料先合成叔丁酯氨曲南,然后在酸性条件下水解获得α-氨曲南,再通过无水乙醇条件下转晶获得β-氨曲南,并对合成产物进行表征。实验结果表明,合成产物为β-氨曲南,理化性质均能达到国家药品要求。     

压力变送器检定标准实验室应用初探

根据JJG882—2004压力变送器检定规程和JJF1033—2008计量标准考核规范,通过研究分析HX6100多功能压力检定系统检定原理及性能和实验室压力变送器检定应用实验研究．推荐适合于压力变送器检定的HX6100多功能压力检定系统,并对该系统在压力变送器栓定中的稳定性、重复性、不确定度等进行了应用效果评价。研究表明,该系统达到了国家标准要求,在压力变送器检定中具有较好的准确性、稳定性和实用性,可以有效地减轻压力变送器的检定工作强度。     

3-噻吩丙二酸的合成研究

3-噻吩丙二酸是β-内酰胺类抗生素替卡西林钠的重要侧链中间体,介绍了用简单、易行的合成路线进行3-噻吩丙二酸的合成研究。由3-溴噻吩制得3-碘代噻吩的过程中,通过实验发现最佳反应条件如下:噻吩、CuI的物质的量比为1∶1.5,原料浓度为1.5mol/L(溶剂为喹啉),反应时间为20h,反应温度为140℃时,反应收率可由原来的42.0%提高到68.3%。其熔点与文献报道一致,结构经红外光谱、核磁共振谱得以确认。中试较小试收率提高2.78%。     

聚乙烯辐照交联的研究进展

1前言聚乙烯是一种广泛应用于日常生活及工农业生产中的高分子。作为半晶材料,其性能强烈依赖于内部的聚集态结构。聚乙烯链的规整性赋予其良好的结晶能力,结晶度可在很大范围内变化。另一方面,链与链之间缺乏紧密的结合力,使得整个聚乙烯材料     

N，N-二己基丙烯酰胺的合成

疏水缔合水溶性聚合物是指聚合物亲水性大分子链上带有少量疏水基团的水溶性聚合物。在水溶性大分子链上引入少量的疏水基团使其水溶液表现出独特的流变性能。正是由于这种独特的溶液性质。它可能在许多领域得到应用，如三次采油、制药、太阳能转换、化妆品、涂料、水处     

沈阳龙马耐酸泵制造厂

企业产品主要有两大系列：一、FS、FSZ、FSY、Q41F—10系列玻璃钢泵阀：玻璃钢具有质轻、强度高、耐腐蚀性能好等特点，是隔热、隔音、绝缘性能都很好的材料，通过选用不同树脂配方及成型方法可适应不同的耐腐蚀要求。FS系列泵为单级悬臂式离心泵，输送温度为0-120度，泵的过流部分可以用环氧玻璃钢、酚醛玻璃钢、玻璃纤维增强聚丙稀制成，满足不同客户需要。可选用HX型内装密封、K型动力密封、T型软填料密封、WB2外装密封。     

聚合工艺重点参数的监控及安全控制

聚合工艺普遍应用在塑料、合成橡胶、化学纤维、涂料等工业中,是生产高分子聚合物的主要反应。根据不同的反应机理,聚合工艺可分为逐步聚合和连锁聚合,连锁聚合中又可分为自由基型聚合、离子(阴离子或阳离子)型聚合及配位络合聚合。从聚合的方法分又可分为本体法、溶液法、乳液法、悬浮法等不同的聚合方法。1.聚合工艺的特点及对安全操作的影响高放热、高粘度是聚合工艺共同的特点。带压操作是许多聚合工艺的操作条件,少数超高压聚合工艺其反应压力甚至超过     

科技专题

芳砜纶纤维的四大用途芳砜纶纤维属于对位芳纶系列,学名为聚苯砜对苯二甲酰胺纤维,系由44二氨基二苯砜,33二氨基二苯砜和对苯二甲酰氯的缩聚物制成的纤维。纤维强度为3.0-4.5g/d;伸长率20-25%;初始模量为760kg/mm2;比重为1.416g/cm3。由于芳砜纶既有对位又有间位的结构,大分子链上又有砜基存在,所以具有突出的耐热、耐燃性能,在300℃热空气中加热100小时强力损失小于5%。此外,还有较好的电绝缘性和抗辐射性能。1.防护制品:由于芳砜纶纤维没有熔点,在400℃以上高温下分解,但不熔融,不收缩或仅呈微小收缩;离焰后立即自熄,无阴燃或余燃现象,适…     

浇铸尼龙新型有机复合催化剂的制备方法

浇铸尼龙分子之间有较多的氢键,应用己内酰胺、氢氧化钠和六氢-2H-氮杂卓-2-酮制备的新型复合催化剂,因六氢-2H-氮杂卓-2-酮对于己内酰胺钠化学键的作用,其耐热性能、冲击强度、适应期、微观结构等方面相较于其他产品明显改善,浇铸尼龙的性能更优良。新型复合催化剂能够使浇铸尼龙的耐热性、冲击强度更优化,且结构更加致密规整,适应期更高。     

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.     

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     

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.     

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。     

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。     

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”。     

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。     

Material power and normative conflict in global and local agrifood governance: The lessons of ‘Golden Rice’ in India

This special section aims to investigate the interaction of global and local forces in shaping agrifood governance. It starts from the recognition that a multitude of actors and norms shape today’s agrifood system. The resulting opaqueness of the systems makes it extremely difficult to understand and explain processes and outcomes of agrifood governance. Given the sustainability challenges facing the agrifood system, improvements in our understanding of what the interaction of global and local actors and norms means on the ground are urgently needed, however. The section, therefore, analyses agrifood governance in India across a selected group of cases. It does so by employing a systematic framework emphasizing the material and ideational dimensions of power and their interaction. The section has chosen India as the setting in which to analyze this interaction due to the crucial role the food demand and supply of this rising power plays in today’s agrifood system. This article provides the special sections’ analytical framework, which uses the interplay of material and ideational dimensions of power as a focal lens. In addition, the article applies this framework to an empirical study of the political conflict around GMO foods in India, specifically the case of ‘Golden Rice’.     

蒸汽热量计量应用的探析

研究了石油化工企业的燕汽计量情况,着重对蒸汽热量计量的合理性进行了分析,阐述了蒸汽热量计量的依据及计算方法,以及蒸气热量计量对节能降耗的重要意义.