全文获取类型
收费全文 | 113篇 |
免费 | 4篇 |
专业分类
电工技术 | 1篇 |
综合类 | 1篇 |
化学工业 | 55篇 |
金属工艺 | 4篇 |
机械仪表 | 1篇 |
建筑科学 | 2篇 |
能源动力 | 3篇 |
轻工业 | 28篇 |
无线电 | 6篇 |
一般工业技术 | 7篇 |
冶金工业 | 7篇 |
自动化技术 | 2篇 |
出版年
2023年 | 4篇 |
2022年 | 3篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 5篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2014年 | 5篇 |
2013年 | 15篇 |
2012年 | 3篇 |
2011年 | 2篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2007年 | 4篇 |
2006年 | 4篇 |
2005年 | 7篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 3篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1991年 | 1篇 |
排序方式: 共有117条查询结果,搜索用时 15 毫秒
41.
Solid-phase crystallisation of Si thin films on glass fabricated by plasma enhanced chemical vapour deposition is compared at different annealing temperatures. Four independent techniques, optical transmission microscopy, Raman and UV reflectance spectroscopy, and X-ray diffraction, are used to characterise the crystallisation kinetics and film properties. The 1.5 μm thick films with the n+/p−/p+ solar cell structure have incubation times of about 300, 53, and 14 min and full crystallisation times of about 855, 128, and 30 min at 600 °C, 640 °C, and 680 °C respectively. Estimated activation energies for incubation and crystal growth are 2.7 and 3.2 eV respectively. The average grain size in the resulting polycrystalline Si films measured from scanning electron microscopy images gradually decreases with a higher annealing temperature and the crystal quality becomes poorer according to the Raman, UV reflection, and X-ray diffraction results. The dopant activation and majority carrier mobilities in heavily doped n+ and p+ layers are similar for all crystallisation temperatures. Both the open-circuit voltage and the spectral response are lower for the cells crystallised at higher temperatures and the minority carrier diffusion lengths are shorter accordingly although they are still longer than the cell thickness for all annealing temperatures. The results indicate that shortening the crystallisation time by merely increasing the crystallisation temperature offers little or no merits for PECVD polycrystalline Si thin-film solar cells on glass. 相似文献
42.
43.
Hydrolytic degradation of intrinsically amorphous poly(DL -lactic acid) was re-examined in pH 7.4 isoosmolar phosphate buffer at 37°C. Size-exclusion chromatogarphy, X-ray scattering and differential scanning calorimetry were used to monitor molecular weight and morphology changes up to the ultimate degradation stage. It was found that heterogeneous degradation of poly(DL -lactic acid) yielded a crystalline residual material of low molecular weight. Comparison with a stereocomplex made of equimolar poly(L -lactic acid) and poly(D -lactic acid) showed that the poly(DL -lactic acid) degradation residue was actually an oligomeric stereocomplex. The formation of stereoregular oligomeric enantiomers agreed well with the predominantly isotactic structure of poly(DL -lactic acid) obtained by ring-opening polymerization of DL -lactide and argued in favour of the stereodependence of main chain ester bond cleavage. 相似文献
44.
Persistent luminescence of Eu/Dy-doped Sr2MgSi2O7 glass-ceramics processed by aerodynamic levitation
《Journal of the European Ceramic Society》2022,42(16):7596-7608
Glass beads of the Sr2MgSi2O7 stoichiometric composition and a non-stoichiometric composition with higher SiO2/SrO ratio doped with Eu2O3/Dy2O3 were prepared through aerodynamic levitation coupled to CO2 laser heating. The glass beads were subsequently treated at 1100 ºC to produce glass-ceramics with Sr2MgSi2O7: Eu2+, Dy3+ as the main crystalline phase. The doped glasses exhibit red emissions; after crystallisation, the corresponding glass-ceramics emit blue light under UV excitation. The starting glass composition considerably affects the crystallisation process, resulting in Sr2MgSi2O7 glass-ceramics with very different microstructures which, in turn, have a significant influence on the luminescence properties. The photoluminescence emission spectra of the glass-ceramics under UV light show a broadband emission (λ = 400–500 nm) with a main peak assigned to the typical Eu2+ transition under excitation at 365 nm. Both the intensity of the emission and the persistence time significatively increase on decreasing temperature. Glass-ceramics from the non-stoichimetric glass composition co-doped with 1Eu2O3/0.5Dy2O3 (mol%.) provided the longest persistence times. 相似文献
45.
《Journal of Experimental Nanoscience》2013,8(2):171-183
Fe-doped nanocrystalline samples of titanium oxide have been synthesised by sol–gel route and conventional sintering process at 450°C under atmospheric conditions. These samples are characterised by X-ray diffraction (XRD), X-ray photoelectron spectroscopy, transmission electron microscopy (TEM) and dielectric property measurement. Samples with Fe content more than 4?mole% crystallises in rutile phase and those with less than 4?mole% crystallises in anatase phase. Nanocrystallite size has been controlled by Fe doping. Crystallite size was found to decrease with Fe concentration in the anatase phase samples whereas reverse happens in rutile phase samples of titanium oxide. There is a slight variation in numerical values of crystallite sizes measured by the two techniques: TEM and XRD peak broadening. The highest crystallite size was 86?nm in 10?mole% Fe-doped samples and the lowest 20?nm in 4?mole% Fe-doped sample. Large dispersions and anomalous values of the dielectric constant, εr were observed at low frequency in anatase phase samples. Rutile phase samples exhibit little dispersion over the measurement frequency range of 20?Hz to 10?MHz. The dielectric constant value of all the samples stabilises to a constant value at higher frequencies. This value is dependent on the final crystalline phase but independent of the crystallite size. The anomalous dielectric behaviour of anatase samples at low frequencies is assigned to the adsorbed –OH ions on the sample surface. 相似文献
46.
M.-W. Choi 《钢铁冶炼》2018,45(5):441-446
The ‘Petrurgic process’ has become a prominent process to address the energy saving issue in the glass ceramic-making process. If the basic oxygen furnace (BOF) slag could be utilised by this process, the environmental problem caused by dumping the waste without recycling might also be resolved effectively. However, it is difficult to directly use BOF slag itself as a valuable material because of high melting point and large amount of iron oxide. Therefore, the current research was focused on elucidating crystallisation behaviour of the iron oxide-devoid BOF slag melt during cooling process with the intention of using the BOF slag to the Petrurgic process. The slag melt showed two crystallisation processes during cooling: the eutectic reaction at the early stage and the diffusion process at the later stage. In addition, the crystallisation mechanism was similar throughout the cooling rate, although the cooling rate influenced the morphology of the crystallisation product. 相似文献
47.
Protein crystallisation is known to be affected by many factors and inherently difficult to control. Being able to model the crystal growth behaviour, especially at process scale for the population of particles in a crystalliser will no doubt greatly help the formulation and controlled manufacture of protein crystals. In this paper, a morphological population balance model for crystallisation of tetragonal Hen-Egg-White (HEW) lysozyme is presented. Since the population balance model has incorporated crystal shape information, it is able to simulate the dynamic evolution of the shape distribution as well as size distribution. The morphological population balance model requires faceted growth kinetics data, which was obtained from published data in literature for the two identified independent crystallographic faces, {1 0 1} and {1 1 0}, of HEW lysozyme crystals. 相似文献
48.
Polyhedral oligomeric silsesquioxane (POSS)/polypropylene (PP) composites in the presence of β-nucleating agent (β-NAs) were prepared by melt-blending, and the interfacial interaction and crystallisation behaviour were investigated. The experimental results indicated that strong hydrogen bonding interactions were generated between amino groups of β-NAs and silicon hydroxyl groups attached to POSS, allowing the absorption/anchoring of the former on the surface of latter. Compared to POSS, β-NAs exhibited higher nucleation effect on PP, as evidenced by an increment of the crystallisation temperature by 7°C in the presence of β-NAs. As a result, the absorbed β-NAs on the surface of POSS not only improved the interfacial interaction between POSS and polymer matrix using interfacial crystallisation but also promoted the formation of β-crystals with toughening effect, which is very important to prepare excellent-performance PP/POSS composite. 相似文献
49.
Yunwei Lin Wenting Yin Yujie Li Guoqin Liu 《International Journal of Food Science & Technology》2022,57(5):2886-2895
This study aimed to investigate the effect of solid lipids (lauric acid (LAU), myristic acid (MYR), stearic acid (STE), glycerol monostearate (GMS), glycerol 1,3-distearate (GDS), glycerol tristearate (GTS), glycerol trimyristate (GTM) and glycerol trilaurate (GTL)) on the characteristics of novel nanostructured lipid carrier (NLC) containing Antarctic krill oil through ultrasound. The fatty acids (LAU, MYR, STE and GMS) were unsuitable solid lipid materials, as apparent stratification was quickly observed during the NLC preparation. NLCs were successfully prepared using GTS, GTM, GTL and GDS. The zeta potential of all NLCs exceeded −30 mV indicating good uniformity and stability. These NLCs appeared spherical or oval. Differential calorimetry and X-ray diffraction analysis revealed these NLCs formed imperfect crystals. As the carbon chain length of triglycerides increased from C12 to C18, the particle size of NLCs increased from 235.8 ± 2.3 nm to 340.5 ± 2.2 nm, the degree of recrystallisation increased from 39.06% to 49.99%, while the EPA encapsulation efficiency decreased from 88.72 ± 0.47% to 72.86 ± 1.06%. NLC prepared with GDS had the smallest particle size (112.4 ± 0.4 nm), the lowest recrystallisation and the highest EPA encapsulation efficiency (>99%). GDS was the most suitable to prepare high encapsulate efficiency krill oil-loaded NLC. 相似文献
50.
This paper reports an investigation of microstructural characteristics in electroless Ni–3·9W–13·4P (wt.%) coating by laser nanocrystallisation using a quantitative X–ray diffraction (XRD) method and scanning electron microscopy (SEM) with energy dispersive X–ray spectroscopy (EDX). The corrosion resistance of the coatings before and after laser treatment has been evaluated in 0·5 M H2SO4 solution by potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) techniques. The results show that the laser treatment improves the corrosion resistance of the coatings. The corrosion mechanism has been studied and correlated to the microstructural characteristics including volume fraction of INi3P/Itotal, microstrain, and the crystallite size of the Ni and Ni3P phases. 相似文献