首页 | 官方网站   微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   207篇
  免费   15篇
  国内免费   2篇
工业技术   224篇
  2023年   4篇
  2022年   4篇
  2021年   5篇
  2020年   3篇
  2018年   3篇
  2017年   3篇
  2016年   5篇
  2015年   13篇
  2014年   12篇
  2013年   9篇
  2012年   13篇
  2011年   17篇
  2010年   11篇
  2009年   14篇
  2008年   9篇
  2007年   13篇
  2006年   13篇
  2005年   12篇
  2004年   11篇
  2003年   11篇
  2001年   9篇
  2000年   8篇
  1999年   4篇
  1998年   4篇
  1997年   5篇
  1996年   2篇
  1995年   1篇
  1994年   3篇
  1992年   1篇
  1985年   1篇
  1984年   1篇
排序方式: 共有224条查询结果,搜索用时 46 毫秒
1.
己二酸二乙酯合成新工艺的研究   总被引:2,自引:0,他引:2  
本文以离子交换树脂作为液固相酯化反应的催化剂 ,甲苯作为带水剂 ,合成己二酸二乙酯。应用本法 ,酯化反应产率高达 78%。同时对影响产率的诸因素进行了考察 ,其最佳反应条件为 :酸醇摩尔比 1∶4 ,催化剂用量为酸质量的 2 5 % ,反应时间为 10小时 ,反应温度 86~ 87℃ ,催化剂重复使用 4次 ,未出现活性明显下降 ,此工艺操作简单 ,反应条件温和 ,产率高 ,具有显著的工业应用价值。  相似文献   
2.
The effects of α‐form and β‐form nuclei on polymorphic morphology of poly(butylene adipate) (PBA) upon recrystallization from the molten state up to various Tmax values were examined by differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD) and polarized light microscopy (PLM). In this study, PBA with complex melting and polymorphism behaviour was used as a model for examining different types and extents of residual nuclei. As the PBA initially containing the sole α‐crystal was brought to a molten state of various Tmax, the extents of trace α‐form crystal nuclei varied and were dependent on Tmax. Furthermore, it did not matter whether, initially, the PBA contained α‐ or β‐form crystals (or both) because only a single type of α‐nuclei could be left upon treatment to the molten liquid state at Tmax. Therefore, only the α‐crystal in PBA had ‘memory capacity’ in the molten liquid state while the β‐crystal did not. This was so because the latter had been completely transformed into the solid state prior to being heated into a liquid. PBA crystallized before α‐nuclei could be packed into α‐crystal, regardless of the crystallization temperature (Tc). For recrystallization from molten PBA without any nuclei, the crystalline polymorphism was correspondingly influenced by Tc. Copyright © 2005 Society of Chemical Industry  相似文献   
3.
以固体超强酸SO2 -4/TiO2 MoO3 为催化剂 ,通过己二酸和正丁醇反应合成了己二酸二丁酯 ,并探讨了诸因素对产率的影响。正交实验结果表明 :SO2 -4/TiO2 MoO3 具有良好的催化活性 ,醇酸物质的量比为 6∶1,催化剂用量为反应物料总质量的 3.3% ,反应时间 1.5h ,反应温度 10 6~ 10 9℃ ,酯收率可达 77.6 %。  相似文献   
4.
6,7-二氢-5H-环戊烷并[b]吡啶主要用于药物、杀菌剂和抗菌剂的研究,也被广泛应用于制备植物保护剂和合成树脂、防老剂以及塑料制品等。目前因其被作为第四代抗生素头孢匹罗的侧链而成为研究者竞相开发的热点。6,7-二氢-5H-环戊烷并[b]吡啶有实用价值的合成方法主要有N-羟基邻苯二甲酰胺法、丙烯醛法和己二酸二乙酯法。丙烯醛法中6,7-二氢-5H-环戊烷并[b]吡啶的收率为87.4%,具有较好的开发前景。  相似文献   
5.
负载钛酸酯催化剂催化合成己二酸二异辛酯   总被引:4,自引:0,他引:4  
聚乙烯醇与四氯化钛在二甲基亚砜和无水乙醇的混合溶剂中反应,制得负载钛酸酯催化剂PVAC-1,用红外光谱对其进行了表征。结果表明:合成中投入3g聚乙烯醇,3mL四氯化钛时,过程容易控制,且催化剂的活性已达很高。确定了在PVAC-1催化作用下,合成己二酸二异辛酯的最佳反应条件及结果:即200℃~210℃下,加入0.3g催化剂,0.1mol己二酸与0.3mol异辛醇反应60min后,己二酸的转化率可达99.7%,PVAC-1重复使用16次后,己二酸的转化率仍保持在96%以匕。  相似文献   
6.
环境友好催化剂催化合成己二酸二乙酯   总被引:7,自引:0,他引:7  
评述了强酸性阳离子交换树脂、十二水合硫酸铁铵、硫酸铜、一水硫酸氢钠、固体超强酸、杂多酸和分子筛催化制备己二酸二乙酯的方法。阐述了在上述催化剂作用下的反应条件、催化剂的性质以及合成工艺的特点,列举了各种催化剂在反应时间、带水剂、产率以及是否可重复使用等方面所具有的优势,指出上述讨论的几种固体催化剂都是合成己二酸二乙酯的优良催化剂。  相似文献   
7.
磷钨酸掺杂聚苯胺催化剂催化合成己二酸二丁酯   总被引:3,自引:1,他引:3  
制备了磷钨酸掺杂聚苯胺催化剂 ,应用于己二酸和正丁醇反应 ,合成了己二酸二丁酯 ,探讨了磷钨酸掺杂聚苯胺催化剂对酯化反应的催化活性 ,研究了原料物质的量比、催化剂用量、反应时间诸因素对产品收率的影响。实验表明 ,磷钨酸掺杂聚苯胺催化剂是合成己二酸二丁酯的良好催化剂 ,在n正丁醇∶n己二酸 =4 .0∶1 ,催化剂用量为反应物料总质量的 1 .0 % ,环己烷为带水剂 ,反应时间 2 .0h的优化条件下 ,己二酸二丁酯的收率可达 79.7%。  相似文献   
8.
Poly(butylene adipate‐co‐terephthalate) (PBAT) composites containing polyaniline (PANI) were prepared using a melt blending process. Acrylic‐acid‐grafted PBAT (PBAT‐g‐AA) and PANI were used to improve the compatibility and dispersibility of PANI within the PBAT matrix. The composites were characterised morphologically using scanning electron microscopy, chemically using Fourier transform IR spectrometry and 13C solid‐state nuclear magnetic resonance, and optically using UV‐visible spectroscopy. The electrical conductivity of the composites was also evaluated with a resistance tester and a cyclic voltameter. Escherichia coli (BCRC 10239) was chosen as the standard bacterium for determining the antibacterial properties of the composite materials. The anti‐static properties of the composites were also evaluated. The PBAT‐g‐AA/PANI composite showed markedly enhanced antibacterial and anti‐static properties due to the formation of amide bonds by the condensation of the carboxylic acid groups of PBAT‐g‐AA with the amino groups of PANI. The optimal level of PANI was 9 wt%, as excess PANI led to separation of the two organic phases, lowering their compatibility. Copyright © 2012 Society of Chemical Industry  相似文献   
9.
Blown films from poly(butylene adipate‐co‐terephthalate) and poly(lactide) (PLA) blends were investigated. The blends were prepared in a twin‐screw extruder, in the presence of small amounts of dicumyl peroxide (DCP). The influence of DCP concentration on film blowing, rheological, mechanical, and thermal properties of the blends is reported in this article. Rheological results showed a marked increase in polymer melt strength and elasticity with the addition of DCP. As a consequence, the film homogeneity and the stability of the bubble were improved. The modified blend films, compared with the unmodified blend, showed an improvement in tensile strength and modulus with a slight loss in elongation. Fourier transform infrared and gel results revealed that chain scission and branching were more significant than crosslinking when the DCP loadings in the blends were not higher than 0.7%. A reduction in melt temperatures of PLA was observed due to difficulty in chain crystallization. The concentrations of DCP strongly affected the melting temperatures but had an insignificant effect on the decomposition behavior of the blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   
10.
甘油氯化制备二氯丙醇过程中会有副产物产生,通过分析二氯丙醇精馏釜余物的组成发现,高沸点物质主要是己二酸酯类,采用酯交换、水解、氢化还原3种方法进行处理,结果发现Pd/C催化加氢效果最好,己二酸的收率92.57%,二氯丙醇的收率78.53%。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号