全文获取类型
收费全文 | 499篇 |
免费 | 6篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 3篇 |
综合类 | 9篇 |
化学工业 | 342篇 |
金属工艺 | 7篇 |
机械仪表 | 1篇 |
建筑科学 | 6篇 |
矿业工程 | 25篇 |
能源动力 | 25篇 |
轻工业 | 17篇 |
水利工程 | 2篇 |
石油天然气 | 15篇 |
无线电 | 2篇 |
一般工业技术 | 55篇 |
冶金工业 | 1篇 |
原子能技术 | 4篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 7篇 |
2020年 | 4篇 |
2019年 | 7篇 |
2018年 | 14篇 |
2017年 | 9篇 |
2016年 | 6篇 |
2015年 | 8篇 |
2014年 | 13篇 |
2013年 | 39篇 |
2012年 | 21篇 |
2011年 | 30篇 |
2010年 | 22篇 |
2009年 | 50篇 |
2008年 | 44篇 |
2007年 | 44篇 |
2006年 | 37篇 |
2005年 | 36篇 |
2004年 | 28篇 |
2003年 | 22篇 |
2002年 | 8篇 |
2001年 | 11篇 |
2000年 | 9篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1988年 | 2篇 |
1987年 | 1篇 |
排序方式: 共有514条查询结果,搜索用时 31 毫秒
31.
本文综述了聚对苯二甲酸丁二醇酯(PBT)/蒙脱土(MMT)纳米复合材料的两种制备方法、性能及其表征方法。用MMT改性PBT可以提高PBT的结晶速率,能改善PBT的热学性能和力学性能,是目前PBT改性的新方向。 相似文献
32.
PVAc/OMMT纳米复合物的制备及其在阻燃PP中的应用 总被引:1,自引:0,他引:1
通过原位乳液插层法制备了有机蒙脱土(OMMT)含量较高的聚醋酸乙烯酯/有机蒙脱土(PVAc/OMMT)纳米复合物,并将其作为阻燃母料与氢氧化镁(MH)复配,与聚丙烯(PP)熔融共混制备了性能良好的无卤阻燃PP,用X射线衍射(XRD)、锥形量热分析(CONE)等对材料进行了表征。结果表明:当OMMT和MH的用量分别为3%和40%时,阻燃PP的热释放速率峰值(PHRR)相比于基体树脂从929.0kW/m2降低至193.7kW/m2,总释放热(THR)从165.2MJ/m2降低到73.6MJ/m2。 相似文献
33.
Christopher Thellen Danielle Froio Jeanne Lucciarini Nandika Ann D'Souza 《Polymer》2005,46(25):11716-11727
Plasticized poly(l-lactide) (PLA) montmorillonite layered silicate (MLS) nanocomposites were compounded and blown-film processed using a co-rotating twin screw extruder. PLA was mixed with 10 wt% acetyltriethyl citrate ester plasticizer and 5 wt% of an organically modified montmorillonite at various screw speeds. Wide-angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM) determined that the compounded pellets and the blown film PLA/MLS nanocomposites were intercalated. The effect of processing screw speeds on the barrier, thermal, mechanical, and biodegradation properties of the nanocomposites were analyzed and compared to the neat polymer. Nanocomposite films show a 48% improvement in oxygen barrier and a 50% improvement in water vapor barrier in comparison to the neat PLA. The thermogravimetric analysis (TGA) showed an overall 9 °C increase in the decomposition temperature for all of the nanocomposites. Differential scanning calorimetry (DSC) has determined that the glass transition, cold crystallization and melting point temperatures were not significantly influenced by the presence of MLS. Mechanical properties of the nanocomposites showed that the Young's modulus increased by 20% and the ultimate elongation of the nanocomposites were not sacrificed in comparison to the neat samples. Biodegradation rates in soil were slightly greater for the PLA/MLS nanocomposite than the pure PLA. However, none of the PLA pure and nanocomposites achieved significant biodegradation levels after 180 days. 相似文献
34.
The effect of sodium montmorillonite source on the morphology and properties of nylon 6 nanocomposites was examined using equivalent experimental conditions. Sodium montmorillonite samples acquired from two well-known mines, Yamagata, Japan, and Wyoming, USA, were ion exchanged with the same alkyl ammonium chloride compound. The resulting organoclays were extruded with a high molecular weight grade of nylon 6 under the same processing conditions. Quantitative analysis of TEM photomicrographs of the two nanocomposites reveal a slightly larger average particle length and a slightly higher degree of platelet exfoliation for the Yamagata based nanocomposite than the Wyoming version, thus, translating into a higher particle aspect ratio. The stress-strain behavior of the nanocomposites appears to reflect the nanocomposite morphology, in that higher stiffness and strengths are attainable with the increased particle aspect ratio. Moreover, the trends in stiffness behavior between the two types of nanocomposites may be explained by conventional composite theory. 相似文献
35.
Leslie S. Loo 《Polymer》2004,45(17):5933-5939
A method to determine the orientation distribution function of montmorillonite clay in nylon 6 nanocomposite films by a combination of infrared (FTIR) trichroic analysis and transmission electron microscopy (TEM) image analysis is described. The structural absorbance of the nanoclay Si-O vibrations was obtained by the sample tilting method described by Schmidt [Schmidt PG. J Polym Sci: Part A 1963;1:1271-1292]. A nonlinear least squares regression was performed to extract the absorbance of individual peaks. The montmorillonite clay orientation in spun cast nylon 6 films can be described by a Gaussian function having a standard deviation of 15° i.e. 95% of the clay platelets are tilted at an angle of within ±30° of the plane of the film. The transition dipole moment angles of the 1018 and 1046 cm−1 clay vibrations are determined to be 18 and 16° relative to the clay surface, respectively. The orientation of nylon 6 in the nanocomposite was also investigated based on the NH stretching mode. The NH bonds are found to be less preferentially oriented along the plane of the film surface compared to pure nylon 6 film. 相似文献
36.
Mechanical and dynamic mechanical properties of various montmorillonite (MMT)/epoxy nanocomposites were investigated. 3-aminopropyltriethoxysilane
functionalized MMT was compared with commercial pristine MMT and ammonium salt substituted MMT. Qualitative evidence of silane
functionalization was confirmed by FT-IR. XRD and TEM were used to characterize the degree of intercalation of MMT in epoxy
nanocomposite. Tensile stress and elongation of MMT/epoxy nanocomposite were improved significantly by the silane functionalization
of MMT. Dynamic mechanical analysis showed that silane functionalization of MMT resulted in active interactions between MMT
and epoxy. 相似文献
37.
A new silicone containing acrylic monomer, methacryloxyethyl polymethylhydrosiloxane ether (MEPMHSE), based on polymethylhydrosiloxane (PMHS) and 2-hydroxyethyl methacrylate (HEMA) has been synthesized for formulation of nanocomposite emulsion. Then Poly (silicone-co-acrylate)/montmorillonite (PSAM)/nanocomposite emulsion were prepared by in situ intercalative emulsion polymerization of methyl methacrylate (MMA), butyl acrylate (BA), methacrylic acid (MAA) and MEPMHSE, in the presence of organic modified montmorillonite (OMMT) with different OMMT contents (0, 0.5, 1.0, 1.5 and 2 wt%) and auxiliary agents in the presence of potassium persulphate (KPS) as initiator. Alkylphenol ethersulphate and Arkupal N-300 were used as anionic and non-ionic emulsifiers, respectively. The resulting monomer was characterized by Fourier transformer infrared spectroscopy (FTIR), proton (1H NMR), and carbon (13C NMR) nuclear magnetic resonance spectroscopes. The OMMT was characterized by FTIR and X-ray diffraction (XRD). The nanocomposite emulsions were characterized by using Fourier transform infrared spectroscopy (FTIR), laser light scattering and surface tension. Thermal properties of the copolymers were studied by using thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMTA) and then the effects of OMMT percent on the water absorption ratio and drying speed were examined. Results showed that OMMT could improve the properties of emulsion, in other words, the properties of nanocomposite emulsion were better when compared with those of the silicone–acrylate emulsion. The property of nanocomposite emulsion containing 1 wt% OMMT was the best one, and the following advantages were obtained: smaller particle size, faster drying speed, smaller surface tension, and improved resistant water by the incorporation of OMMT. 相似文献
38.
María?Luz?Pérez-Rea Fernando?Rojas Victor?M.?CastanoEmail author 《Materials Research Innovations》2003,7(6):341-352
One of the most important structural parameters involved in the characterization of the void space of soils is the pore size distribution. In this work, a nitrogen adsorption method is presented as an alternative to determine the mesopore contribution of slit-shaped pores to the abovementioned parameter in montmorillonite-containing soils. The mesopore size structural parameter obtained via this sorption method is related to montmorillonite d001 interlayer distances proceeding from either X-ray or electron diffraction analysis, if only by assuming during sorption analysis that mesopores resident inside clay grains adopt slit-shaped geometries. Mineralogical analysis and determination of some important geotechnical properties of these montmorillonite-containing soils complement the preceding sorption and structural studies. 相似文献
39.
Ammonia borane (AB) is an intriguing molecular crystal material with extremely high hydrogen density. In the present study, we prepared ruthenium (Ru) nanoparticles immobilized in montmorillonite (MMT) and examine its catalytic effect on the methanolysis reaction of AB. The Ru/MMT catalyst was prepared by cation-exchange method followed by hydrogen reduction at elevated temperatures. Property examinations found that the Ru/MMT catalyst was highly effective and robust for promoting the methanolysis reaction of AB. For example, the methanolysis system employing Ru/MMT catalyst exhibited an average hydrogen generation rate of 29 L min−1 g−1 (Ru). The catalyst at its twentieth usage retained 95% of its initial activity and ensured 100% conversion of AB. Kinetics studies found that the methanolysis reaction of AB employing Ru/MMT catalyst follows first-order kinetics with respect to AB concentration and catalyst amount, respectively. 相似文献
40.
介绍了用矿物化学成分分析法计算蒙脱石化学式的步骤和结果。Crook-County蒙脱石的化学式为(Si_(3.98)Al_(0.02)~N(Al_(1.63)Mg_(0.15)Fe_(0.22)O_(10)(OH)_2Na_(0.39),分子量为376.7。实验结果表明,此方法的可行性取决于蒙脱石的纯化程度。比较蒙脱石阳离子交换容量的测定值与根据化学式计算值的接近程度,可以对蒙脱石的纯化程度作出评价。 相似文献