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排序方式: 共有194条查询结果,搜索用时 31 毫秒
1.
光电设备电子机柜布线工艺研究 总被引:5,自引:0,他引:5
作为信号和电能载体的导线,同时也是噪声的载体和外来噪声侵入设备的媒体。描述了噪声通过导线侵入设备内部的方式,通过降低噪声的途径确定了机柜布线的原则,介绍了布线的要求和方法,最后提出了用布线槽布线的建议。 相似文献
2.
Patrick Dehornoy 《Algebra Universalis》2002,48(2):223-248
We solve the word problem of the identity x(yz) = (xy)(yz) by investigating a certain group describing the geometry of that identity. We also construct a concrete realization of the
one-generated free algebra relative to the above identity.
Received March 23, 2001; accepted in final form July 6, 2002. 相似文献
3.
Chi-So Lee 《中国化学会会志》1987,34(3):207-210
A differential pulse polarographic method for the determination of nitrate ion has been developed. With 0.5 M CaCl2 as supporting electrolyte, NO?3 is reduced to give a peak with E1/2=–1.836 Volt vs. the Ag/AgCl electrode. The differential pulse polarographic peak height is proportional to the nitrate concentration from 20 to 60 ppm. The detection limit for nitrate is 2 ppm in pure aqueous solution. In the determination of 40 ppm nitrate a relative precision (relative standard deviation) of less than 2% was achieved. Nitrite interferes seriously and should be absent if accurate results are required. The method has been applied to the determination of nitrate in Ammonium Uranyl Tricarbonate (AUT) Solution, results obtained by this method are compared to those obtained by ion chromatography. The agreement between the two sets of results suggests that the DPP method can be used with a fair degree of confidence. 相似文献
4.
Fengyang Deng Bin Xu Yong Gao Zheng Liu Duanguang Yang Huaming Li 《Journal of polymer science. Part A, Polymer chemistry》2012,50(18):3767-3774
In this study, a series of linear poly(triazole)s (PTAs) were successfully synthesized by the metal‐ and solvent‐free, thermal click polymerization of diazide and dialkyne (A2 + B2) monomers. All click polymerizations proceeded smoothly at 80 °C in an open atmosphere without protection from oxygen and moisture. After being polymerized for 36 h, the crude polymer was further fractionated into three fractions using a multistep precipitation method. By selectively choosing precipitating agents, this process produced poly(triazole) fractions with low polydispersity index (<1.30). The resulting PTAs are soluble in common organic solvents and stable at a temperature up to 320 °C. Furthermore, the methyl benzoate moieties in the main chain can serve as useful building blocks for further postpolymerization functionalization, yielding 1,2,4‐triazole derivatives. This functionalization strategy offers potential for the development of novel triazole‐based materials. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
5.
A facile method to synthesize high‐molecular‐weight biobased polyesters from 2,5‐furandicarboxylic acid and long‐chain diols 下载免费PDF全文
Vasilios Tsanaktsis George Z. Papageorgiou Dimitrios N. Bikiaris 《Journal of polymer science. Part A, Polymer chemistry》2015,53(22):2617-2632
In this study, biobased furan dicarboxylate polyesters have been prepared using 2,5‐furandicarboxylic acid (FDCA) and diols with high number of methylene groups (long‐chain diols), namely, 8, 9, 10, and 12. Because of the high boiling points of these diols, a modified procedure of the well‐known melt polycondensation was applied in this work. According to this, the dimethyl ester of FDCA (DMFD) reacted in the first transesterification stage with the corresponding diols forming bis‐hydroxy‐alkylene furan dicarboxylates (BHFD). In the second stage, the BHFD reacted with DMFD again at temperatures of 150–170 °C (for 4–5 h), and in the final stage, the temperature was raised to 210–230 °C (vacuum was applied for 2–3 h). The molecular weight of the polyesters and the content of oligomers, as was verified by gel permeation chromatography analysis, depend on the polycondensation time and temperature. The chemical structure of the polyesters was verified from 1H NMR spectroscopy. All the polymers were found to be semicrystalline, with melting temperatures from 69 to 140 °C depending on the diol used. In addition, the mechanical properties also varied with the type of diol. The higher values were observed for poly(octylene 2,5‐furanoate), whereas the lowest values were observed for poly(dodecylene 2,5‐furanoate) with the higher number of methylene groups in its repeating unit. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2617–2632 相似文献
6.
巧用Word绘制有线电视图纸 总被引:1,自引:0,他引:1
给Word的工具栏中添加“有线电视”专用绘图工具栏,充分开发Word的图文编辑功能,实现有线电视设备或其他元器件单元图形的即点即输,可非常方便地编辑出图文并茂的有线电视专业文稿。 相似文献
7.
本文首先简要介绍了IPv6及其地址的特点,然后描述了在Windows 2003环境下如何安装IPv6协议和配置IPv6地址,最后给出了利用Apache构建基于IPv6的Web服务器的实现过程。 相似文献
8.
目前,在许多工程开发的过程中,都要和数据库相关联。例如:Oracle 9i,SQL Server 2000和Access 2003等。虽然每种数据库与Visual Studio.NET 2003中的C#连接方式多种多样,但也有很多相似之处,可以将相似的地方用统一方法写成实用的接口。这样可以很好地对C#Windows Forms程序和ASP.NET程序进行架构的组织,配合微软最近推出的ASP.NET 2.0版本的架构。可以将数据实体层(即数据库层)、业务逻辑层、界面表示层等进行分类。针对这3种数据库与C#.NET接口的相似性来写一种具有统一模式的接口。 相似文献
9.
由于具有较高的安全性、灵活性和可扩展性,VLAN技术得到了广泛的应用。针对当前VLAN设备市场存在的缺点,设计开发了型号为IDS-2003的VLAN设备。IDS-2003具有24个10BaseT/100BaseTx以太网接口、2个千兆以太网口,以及1个ATM口,支持基于端口和标签2种方式划分VLAN,最多达4096个。IDS-2003设计简单,CPU为MPC862,以太网交换机芯片选用Allayer的A1320,AL125和A11022;ATM接口利用了MPC862的ESAR功能。软件采用模块化设计。IDS-2003作为一种宽带业务接入器,具有丰富的业务接入能力,能同时接入数据、语音和图像业务,可满足各种不同速率的要求。 相似文献
10.