全文获取类型
收费全文 | 700篇 |
免费 | 10篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 6篇 |
综合类 | 18篇 |
化学工业 | 375篇 |
金属工艺 | 18篇 |
机械仪表 | 15篇 |
建筑科学 | 59篇 |
矿业工程 | 13篇 |
能源动力 | 10篇 |
轻工业 | 64篇 |
水利工程 | 3篇 |
石油天然气 | 11篇 |
武器工业 | 4篇 |
无线电 | 18篇 |
一般工业技术 | 88篇 |
冶金工业 | 4篇 |
原子能技术 | 7篇 |
自动化技术 | 3篇 |
出版年
2023年 | 12篇 |
2022年 | 12篇 |
2021年 | 13篇 |
2020年 | 12篇 |
2019年 | 9篇 |
2018年 | 10篇 |
2017年 | 21篇 |
2016年 | 12篇 |
2015年 | 19篇 |
2014年 | 28篇 |
2013年 | 62篇 |
2012年 | 38篇 |
2011年 | 42篇 |
2010年 | 27篇 |
2009年 | 32篇 |
2008年 | 31篇 |
2007年 | 29篇 |
2006年 | 30篇 |
2005年 | 25篇 |
2004年 | 37篇 |
2003年 | 36篇 |
2002年 | 35篇 |
2001年 | 31篇 |
2000年 | 21篇 |
1999年 | 18篇 |
1998年 | 25篇 |
1997年 | 12篇 |
1996年 | 7篇 |
1995年 | 11篇 |
1994年 | 9篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 3篇 |
排序方式: 共有716条查询结果,搜索用时 0 毫秒
1.
N. JostJ. Karger-Kocsis 《Polymer》2002,43(4):1383-1389
Curing kinetics of a vinylester-urethane hybrid (VEUH) resin consisting of vinylester resin (VE) diluted in styrene and novolac type polyisocyanate (NPI) have been studied by differential scanning calorimetry (DSC). As VEUH is crosslinked via free radical polymerisation between the vinyl functions of styrene and VE, and polyaddition reaction between the secondary -OH groups of VE and -NCO of NPI, it was necessary to study these reactions separately. This was achieved by studying the curing with and without incorporating the NPI. The curing reaction was monitored by measuring the heat of reaction under isothermal and dynamic temperature conditions. Models describing the curing were developed, which are in good agreement with the experiments. A comparison between the curing of the VEUH and the VE resin without NPI leads to the conclusion that the curing of the VEUH as accessed by DSC is dominated by the radical polymerisation of styrene with VE although the two reactions are not time separated. 相似文献
2.
Ingo Alig Dirk Lellinger Harald Oehler Sergey A. Adamovsky Christoph Schick 《Progress in Organic Coatings》2008,61(2-4):166-175
A new microcalorimeter with eight parallel channels using robust, low cost sensors for characterization of coatings and adhesives is described and first experiments on coatings and adhesives are presented. The calorimetric sensors are based on thin glass plates (20 mm × 20 mm, thickness 150 μm) with heater and thermocouple sputtered on the surfaces (calorimetric active area of about 9 mm2). The setup allows heating and cooling experiments as well as isothermal measurements in the temperature-modulated mode with up to eight sensors in parallel. The measured quantities are the real (C′p) and imaginary part (C″p) of the complex heat capacity (), the related absolute value of the heat capacity () and the heat flow . An industrial computer (NI PXI system) with specific software for calibration and data recording controls the electronic components. Sensors can be embedded in a temperature controlled oven (heating and cooling by Peltier elements) or alternatively in a climatic cabinet with controlled temperature and humidity.
The method has been applied successfully to monitoring of film formation of aqueous polymer dispersions (styrene-acrylate copolymer) and curing of coatings. 相似文献
3.
介绍一种新型酚醛--丁腈并用耐高温高强度单组分浆状结构胶粘剂和组成比例以及固化条件对粘接强度的影响,该胶适用于粘接刹车制动蹄和飞机轻金属结构等。 相似文献
4.
室温固化高温使用环氧胶粘剂的进展 总被引:3,自引:1,他引:3
本文介绍了室温固化高温使用环氧胶粘剂的主要成份、结构、性能及其特点,并对其存在的问题及未来的发展趋势化了简述. 相似文献
5.
A novel bisphenol(1,2-dihydro-2-(4-((4-hydroxy)phenyliminomethylidene)phenyl)-4-(4-((4-(4-hydroxy)phenyliminomethylidene)phenoxy)phenyl)(2H)phthalazin-1-one, DPP) and a diamine(1,2-dihydro-2-(4-aminophenyl)-4-(4-(4-aminophenoxy)phenyl)(2H)phthalazin-1-one, DAP) were synthesized and characterized. The novel epoxy polymers containing phthalazinone and/or azomethine moieties were prepared by binary polymerization of DAP (or DPP) with diglycidyl ether of biphenyl A (DGEBA) and ternary polymerization of hybrid curing agents, DAP/DPP (DAP and DPP under different molar ratios) with DGEBA. The cure behaviors of these new epoxy systems were studied by dynamic differential scanning calorimeter (DSC) and Infrared (IR) scans. Especially, the activation energy of DAP/DGEBA calculated by Kissinger and Ozawa methods were 73.8 and 77.4 kJ/mol, respectively. For ternary epoxy system, it was found that hybrid curing agents of DAP/DPP exhibited significant associated effect on their reactivity towards the oxirane group. Glass transition temperatures (Tg's) of these new epoxy polymers were all above 150 °C from the results of DSC, and the initial thermal decomposition temperatures (Td,5%'s) and integral procedure decomposition temperatures (IPDT's) of these new epoxy polymers are above 350 and 850 °C, respectively from results of thermogravimetric analyses (TGA). These results show that new epoxy polymers containing phthalazinone and/or azomethine moieties exhibited excellent thermal properties. Especially, thermal properties of the ternary epoxy polymers could be modified by changing the content of DAP and DPP. The linear relationships between char yield (Yc,wt%) and the structural compositions of these new polymers (weight percentage of phthalazinone, azomethine and nitrogen, C/H weight ratio) were built. 相似文献
6.
Recent studies have shown that cobalt catalysts, used for curing of alkyd coatings, are potentially carcinogenic, and hence replacement by new environmental friendly catalysts is needed. The influence of different metal based catalysts on the oxidation process has been studied extensively in model systems, consisting of unsaturated oils. However, these results may not be representative for real coatings, since in these systems the oxygen diffusion is much lower than in model systems and therefore may have a large effect on the curing. In this paper, we will show how the curing of an alkyd coating depends on the type of catalyst (cobalt or manganese based). The curing process is studied using a high spatial resolution nuclear magnetic resonance (NMR) setup. The final network structure and cross-link density are found to be correlated with the catalyst used, i.e. a cobalt based catalyst and two manganese based catalysts. The difference in final network structure is investigated by NMR T2 relaxation analysis and the glass transition temperature Tg measured using a differential scanning calorimeter (DSC). In case of the cobalt based catalyst a cross-linking front was observed and a high cross-link density was found, compared to the manganese based catalysts, in which case no sharp cross-linking front was observed. To interpret the observed NMR profiles in more detail, simulations based on a reaction-diffusion model were performed. From the results of these simulations estimates were obtained for the reaction constants and the diffusion of oxygen for the different catalysts. 相似文献
7.
Mechanistic approach to the curing of carboxylated nitrile rubber (XNBR) by zinc peroxide/zinc oxide
The crosslinking of carboxylated nitrile rubber (XNBR) with a special preparation based on zinc oxide/zinc peroxide (Struktol ZP1014) is studied. It is shown that ionic species, by metallic salts formation, and covalent crosslinks, by zinc peroxide decomposition, are formed. The complete process can be empirically split in two contributions, with mathematical modeling rendering a satisfactory fit to experimental data. However, infrared and calorimetric analyses support the contribution of at least three mechanisms to the torque build-up: a very fast ionic species formation process by the initial zinc oxide present; covalent crosslinks and additional ionic species formation coming from zinc peroxide decomposition and contributing at all times from the beginning but decaying with time; and a third, not yet determined, contribution that accounts for the torque increment at long times. 相似文献
8.
通过正交试验获得磷石膏—矿渣—粉煤灰—石灰—水泥胶凝体系的优化配合比为磷石膏∶矿渣∶粉煤灰∶生石灰∶水泥=30∶25∶24.5∶10.5∶10,并通过XRD、SEM微观分析手段和宏观测定强度的方法探讨了养护制度对该胶凝体系性能的影响。研究结果表明:该胶结料90℃下蒸养7 h,然后自然养护,28 d抗压强度高达43.9MPa,凝结时间正常,耐水性良好。胶结料强度随养护温度的升高而增加;90℃下,胶结料强度随蒸养时间的增加而增加,此温度下蒸养13 h所得制品,7 d抗压强度便达到39.6 MPa。利用最优配比成型的免烧砖能达到非烧结粘土砖15级的要求。 相似文献
9.
环氧与酚醛改性环氧涂层固化反应与吸水性关系的研究 总被引:3,自引:0,他引:3
采用示差扫描量热分析技术,研究了一种环氧树脂粉末涂料与酚醋改性的该种涂料的固化反应机制和两种涂膜的交联结构,并结合两种涂膜有90℃蒸馏水中的静态浸泡实验结果,分析了涂膜交联结构对涂膜吸水性的影响。结果表明:酚醛改性环氧粉末涂料的固化反应包括酚醛树脂与一部分环氧树脂的共聚反应,环氧树脂与固化剂的交联反应,以及少量酚醛树脂的自聚反应。而环氧粉末涂料的固化反应只有环氧树脂与固化剂-双氰胺的交联反应。酚醛 相似文献
10.