全文获取类型
收费全文 | 375篇 |
免费 | 35篇 |
专业分类
电工技术 | 3篇 |
综合类 | 2篇 |
化学工业 | 290篇 |
金属工艺 | 3篇 |
机械仪表 | 10篇 |
矿业工程 | 2篇 |
能源动力 | 1篇 |
轻工业 | 1篇 |
石油天然气 | 1篇 |
无线电 | 2篇 |
一般工业技术 | 88篇 |
冶金工业 | 7篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 1篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 11篇 |
2015年 | 11篇 |
2014年 | 25篇 |
2013年 | 26篇 |
2012年 | 33篇 |
2011年 | 42篇 |
2010年 | 46篇 |
2009年 | 43篇 |
2008年 | 42篇 |
2007年 | 47篇 |
2006年 | 44篇 |
2005年 | 9篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 2篇 |
排序方式: 共有410条查询结果,搜索用时 250 毫秒
1.
If a low weight percentage of crude fine fillers can improve properties of polymer materials directly without complicated chemical treatment process involved, it will be significant for many industrial applications. Our previous study indicated that a kind of Cancun natural sand could be an effective filler material for polymer composites. In this current work, the epoxy composites reinforced by this kind of natural sand particles were prepared and thermal and mechanical properties of the composites containing up to 5 wt % of the sand particles were characterized. Results showed that the highest flexural strength appears in the epoxy composite containing 1 wt % sand particles. A damage model was used to interpret the flexural properties, which showed an acceptable agreement with the experimental results. The glass transition temperature, high temperature storage modulus, and dimensional stability of the sand/epoxy composites monotonically increased with the addition of the sand particles. The sand particle/epoxy composites also displayed a noticeable enhancement in thermal conductivity. Theoretical analysis showed that in addition to conduction, other heat transport mechanisms played roles in the improved heat transmission through the composites. As a natural porous micron-scale material, Cancun sand has the potential for applications in cost-effective composites with enhanced mechanical and thermal properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
2.
3.
通过熔体插层法以及常压硫化法制备了橡胶/黏土纳米复合材料,并与模压硫化法制备的复合材料进行了对比,研究了硫化方法对橡胶/黏土纳米复合材料微观分散状态的影响。结果表明:采用熔体插层法制备的橡胶/黏土混合物,其受限状态的橡胶大分子链在高温、高压条件下,在黏土片层之间处于一种热力学不稳定状态;模压处理会对橡胶/黏土混合物的分散状态产生不利影响。透射电子显微镜和X光衍射分析表明,采用模压硫化、常压硫化得到的丁基橡胶或丁苯橡胶/黏土纳米复合材料中黏土片层的微观分散状态不同;排除压力的影响,常压硫化有利于提高橡胶/黏土纳米复合材料中黏土片层的分散程度。 相似文献
4.
吡咯烷基-N-甲酸,丙烯酸乙二醇酯的合成及其光聚合动力学的研究 总被引:1,自引:0,他引:1
合成了不含氢键的低粘度的吡咯烷基-N-甲酸-丙烯酸乙二醇酯(PLW),并采用实时红外光谱法检测了光强和光引发剂浓度对光聚合动力学的影响。随着光强的增加光聚合的最终转化率基本不变,但是光聚合速率有明显的增加,并且达到最大聚合速率的时间也缩短。随着光引发剂浓度的增加,最终转化率和最大聚合速率都有了显著的增加。所合成单体的转化率在30 s内能达到90%以上。 相似文献
5.
The interfacial mechanism and structure of poly(ethylene-co-methacrylic acid)/copper were investigated using reflection-absorption infrared spectroscopy (RAIR). Based on IR spectrum of EMAA/copper, a strong absorption peak appearing at approximate 1,600 cm−1 is attributed to the asymmetric stretching vibration of COO― (υCOOas―) and a relatively weak absorption band at 1,375 cm−1 is assigned to the symmetric stretching vibration of COO― (υCOOs―). Therefore, it can be determined that copper interacts with EMAA through a strong ionic interaction and carboxylate structure is formed in the interfacial regions. And, according to the band intensities of carboxylate stretching modes and different sensitivities of RAIR to perpendicular and parallel transition moments, it can be concluded that EMAA is absorbed onto a copper substrate with a configuration in which the twofold axis of the C2υ point group for carboxylate group inclines certain degree from the normal to the surface. In addition, the interfacial carboxylate structure of EMAA/copper is confirmed to be a monodentate one through calculating the difference (Δυ)between the asymmetric carboxylate stretch (υCOOas―) and the symmetric stretch (υCOOs―). 相似文献
6.
In order to improve the dispersion of silica in rubber matrix and to avoid volatility and extractability of the antioxidants, antioxidant functionalized silica is synthesized through reaction of precipitated silica and antioxidant coupling agent which is synthesized by (3-glycidyloxypropyl)trimethoxysilane (A-187) and N-phenyl-1,4-phenylenediamine (PPDA). This antioxidant functionalized silica with different antioxidant content is then incorporated into styrene–butadiene rubber (SBR) to study their reinforcement and antioxidation effects. The tensile strength of these composites is much higher than that of neat silica/SBR, and increases with increasing antioxidant content. It is close to that of bis(triethoxysilylpropyl)tetrasulfane (TESPT) modified silica/SBR when the antioxidant content exceeds 3.9% (by weight to silica). Furthermore, SBR filled with antioxidant functionalized silica has greatly improved stability in thermal oxidative ageing and damp heat ageing. 相似文献
7.
At present, the synthesis of body temperature triggering shape memory polymers usually requires elaborate structural design, which limits their wide application. Herein, starting from bio-based Eucommia ulmoides gum (EUG), a series of EUG/silica hybrids (ESHs) are prepared through a facile one-pot process, in which EUG is epoxied and then self-crosslinked with SiO2 by epoxy ring-open reaction. Varying the amount of H2O2, the shape memory transition temperature (Ttrans) of ESHs is adjusted to 47.4–36.6 ℃, which is close to human body temperature (37 ℃). Among them, ESH-17 exhibited the best body temperature triggering shape memory ability (Ttrans = 36.6 ℃), which can restore the permanent shape within 60 s at 37 ℃ with a shape fixity ratio of 99% and shape recovery ratio near 100%. In addition, the shape memory mechanism is discussed and shows some application scenarios of ESHs. The as-produced materials can be used as smart biomaterials such as self-tightening sutures, self-sealing root canal filling materials, and so on. 相似文献
8.
9.
Synthesis and application of an alternative plasticizer Di(2‐Ethylhexyl)‐1,2‐cyclohexane dicarboxylate 下载免费PDF全文
Cyclohexane dicarboxylic acid esters are environmentally friendly and non‐toxic plasticizers, and have similar performance with phthalates which have potential toxicity to human health. In this article, di(2‐ethylhexyl)‐1,2‐cyclohexane dicarboxylate (DEHCH) was synthesized via esterification between hexahydrophthalic anhydride (HHPA) with iso‐octanol by using concentrated sulfuric acid as a catalyst. The effects of reaction parameters on esterification were studied by investigating the temperature, reaction time, molar ratio of iso‐octanol‐to‐HHPA, and catalyst content. Conversions of HHPA to esters were determined. Functional group analysis was conducted by using FTIR and 1H‐NMR spectroscopy. PVC compounds after addition of the synthesized plasticizer DEHCH presented similar plasticizing performance with DEHP and DINCH, as demonstrated by comparisons of the results of mechanical properties, transparency, and volatilization and migration tests obtained for plasticized PVC compounds. DEHCH can also be considered as an alternative plasticizer for DEHP. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39763. 相似文献
10.
Perfluorosulfonated ionomers membranes: Melt‐processing and characterization for ion exchange applications 下载免费PDF全文
Perflurosulfonated ionomers membranes with different ionic‐exchange capacity were successfully fabricated via melt‐extruding and casting of their –SO2F precursors. A systematical investigation of the thermal stability, crystallinity, and rheological properties of the precursors was performed to secure their optimized processing conditions. The tensile properties of acid‐form membranes are found to increase with base‐hydrolysis time, where a tensile strength of 38.2 MPa is readily obtained after 24 h's base‐hydrolysis. The content of –SO2F or –SO3H containing side‐chains plays an important role in the thermal stability, rheological, and mechanical properties of the precursor or the acid‐form membranes. The strong ionic interactions, attributed to the –SO3H groups, lead to decreased crystallinity and tensile strength for different IEC membranes. The acid‐form membranes exhibit good proton conductivity and low methanol crossover in comparison with reference Nafion membrane. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39944. 相似文献