全文获取类型
收费全文 | 97篇 |
免费 | 5篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 19篇 |
金属工艺 | 2篇 |
机械仪表 | 2篇 |
建筑科学 | 3篇 |
能源动力 | 8篇 |
轻工业 | 25篇 |
无线电 | 1篇 |
一般工业技术 | 31篇 |
冶金工业 | 1篇 |
自动化技术 | 9篇 |
出版年
2023年 | 2篇 |
2022年 | 6篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2014年 | 8篇 |
2013年 | 6篇 |
2012年 | 5篇 |
2011年 | 9篇 |
2010年 | 5篇 |
2009年 | 7篇 |
2008年 | 10篇 |
2007年 | 3篇 |
2006年 | 4篇 |
2005年 | 5篇 |
2004年 | 1篇 |
2003年 | 1篇 |
1998年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1986年 | 1篇 |
排序方式: 共有102条查询结果,搜索用时 15 毫秒
31.
Helium‐aided sintering of porous unsintered glass is a complex multiscale process, characterised by three different timescales, namely, that of helium diffusion, heat conduction, and radial shrinkage of the glass core. This work presents a multiscale model for quantifying heat and helium diffusion in a shrinking core system by decoupling the timescales based on their orders of magnitude. We obtain analytical solutions of our model, which allow us to quantify the spatio‐temporal profiles of temperature and helium concentration in the glass during the sintering process. Our results show that the introduction of helium increases the sintering rate of glass, and we conclude that pre‐sintering heating followed by helium‐aided sintering is better than simultaneous heating and helium diffusion. We also show that the pre‐sintering heating process for a standard glass sample should not be longer than an hour for the sake of heat economy, following which we may switch to the helium‐aided sintering process, where the sintering should occur under isothermal conditions for approximately 6 h. We perform dynamic simulations using glass porosity as a parameter, and find the sintering rate to be directly proportional to the initial porosity of the glass sample. 相似文献
32.
Conjugated polymers have been the subject of many studies because of their widespread applications in electronic and optoelectronic devices. Poly(p‐phenylene vinylene) is a leading semiconducting polymer in optical applications. This work is focused on the development of thin films of poly(p‐phenylene vinylene) by spin coating and their characterization with Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy to understand their changes. An empirical model has been developed to show the effect of the variables—the spin speed, polymer concentration, and spin time—on the film thickness. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
33.
Asman Tamang Hitoshi Sai Vladislav Jovanov Mohammad I. Hossain Koji Matsubara Dietmar Knipp 《Progress in Photovoltaics: Research and Applications》2016,24(3):379-388
Light trapping and photon management in honeycomb‐textured microcrystalline silicon solar cells are investigated experimentally and by modeling of the manufacturing process and the optical wave propagation. The solar cells on honeycomb‐textured substrates exhibit short circuit current densities exceeding 30 mA/cm2 and energy conversion efficiencies of up to 11.0%. By controlling the fabrication process, the period and height of the honeycomb‐textured substrates are varied. The influence of the honeycomb substrate morphology on the interfaces of the individual solar cell layers and the quantum efficiency is determined. The optical wave propagation is calculated using 3D finite difference time domain simulations. A very good agreement between the optical simulation and experimental results is obtained. Strategies are discussed on how to increase the short circuit current density beyond 30 mA/cm2. In particular, the influence of plasmonic losses of the textured silver (Ag) reflector on the short circuit current and quantum efficiency of the solar cell is discussed. Finally, solar cell structures with reduced plasmonic losses are proposed. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
34.
Very small nanoparticles (size 3-5 nm) of Y2Sn2O7, Y2Sn2O7:Tb3+ and Sb3+ co-doped Y2Sn2O7:Tb3+ were prepared at a relatively low temperature of 700 °C. Y2Sn2O7 host is characterised by an emission around 436 nm, which is arising from the oxygen vacancies present in the lattice. Tb3+ emission improves significantly when Sb3+ ions are co-doped with Y2Sn2O7:Tb3+ nanoparticles. Incorporation of Sb3+ ions at the Y3+ site of Y2Sn2O7 lattice and associated lattice distortion around Tb3+/Y3+ ions brought about by the difference in the stable coordination number of Sb3+ and Y3+ ions are responsible for the improved Tb3+ emission from the co-doped samples. 相似文献
35.
Nanoparticles are now utilized in many diverse biological and medical applications. Despite this, it remains challenging to tailor their surface for specific molecular targeting while maintaining high biocompatibility. To address this problem, we evaluate a phytochelatin-related peptide surface coating to produce functional and biocompatible nanoparticles (NPs) based on fluorescent InP/ZnS and CdSe/ZnS or superparamagnetic FePt and Fe(3)O(4). Using a combination of transmission electron microscopy, size-exclusion chromatography and gel electrophoresis (GE), we demonstrate the excellent colloidal properties of the peptide-coated NPs (pNPs) and the compact nature of the coating (~4?nm thickness). We develop a simple protocol for the monofunctionalization of the pNPs with targeting biomolecules, by combining covalent conjugation with GE purification. We then employ functionalized InP/ZnS pNPs in a live-cell, single-molecule imaging application to specifically target and detect individual proteins in the cell membrane. These findings showcase the versatility of the peptides for preparing compact NPs of various compositions and sizes, which are easily functionalized, and suitable for a broad range of biomedical applications. 相似文献
36.
A total of 176 Acinetobacter isolates, including 57 Acinetobacter baumannii originally obtained from 2,287 bulk tank milk (BTM) samples in Korea was investigated for the genetic basis of antimicrobial resistance using molecular methods. In addition, the occurrence and cassette content of integrons were examined and the genetic diversity of A. baumannii strains identified was evaluated. Aminoglycoside-modifying enzyme genes were detected in 15 (88.2%) of the 17 aminoglycoside-resistant Acinetobacter isolates tested. The most common aminoglycoside-modifying enzyme gene identified was adenylyltransferase gene aadB (n = 9), followed by phosphotransferase genes aphA6 (n = 7) and aphA1 (n = 5). Of the 31 isolates resistant to tetracycline, tet(39) was detected in 20 of them. The genetic basis of resistance to sulfonamide was identified in 15 (53.6%) of 28 trimethoprim-sulfamethoxazole-resistant isolates and 9 (32.1%) of them carried both sul1 and sul2 genes. A blaADC-7-like gene was detected in 1 β-lactam-resistant A. baumannii. Furthermore, class 1 integron was identified in 11 Acinetobacter isolates. Two gene cassettes dfrA15, conferring resistance to trimethoprim, and aadA2, conferring resistance to aminoglycosides, were identified in 8 Acinetobacter isolates. None of the isolates was positive for class 2 or class 3 integrons. Pulsed-field gel electrophoresis revealed that most of the A. baumannii strains from BTM samples were genetically diverse, indicating that the occurrence of A. baumannii strains in BTM was not the result of dissemination of a single clone. Elucidation of resistance mechanisms associated with the resistance phenotype and a better understanding of resistance genes may help in the development of strategies to control infections, such as mastitis, and to prevent further dissemination of antibiotic resistance genes. To the best of our knowledge, this is the first report of molecular characterization of antimicrobial-resistant Acinetobacter spp. from milk. 相似文献
37.
Robindro Singh L Ningthoujam RS Sudarsan V Srivastava I Dorendrajit Singh S Dey GK Kulshreshtha SK 《Nanotechnology》2008,19(5):055201
Nanoparticles of Eu(3+) doped Y(2)O(3) (core) and Eu(3+) doped Y(2)O(3) covered with Y(2)O(3) shell (core-shell) are prepared by urea hydrolysis for 3?h in ethylene glycol medium at a relatively low temperature of 140?°C, followed by heating at 500 and 900?°C. Particle sizes determined from x-ray diffraction and transmission electron microscopic studies are 11 and 18?nm for 500 and 900?°C heated samples respectively. Based on the luminescence studies of 500 and 900?°C heated samples, it is confirmed that there is no particle size effect on the peak positions of Eu(3+) emission, and optimum luminescence intensity is observed from the nanoparticles with a Eu(3+) concentration of 4-5?at.%. A luminescence study establishes that the Eu(3+) environment in amorphous Y (OH)(3) is different from that in crystalline Y(2)O(3). For a fixed concentration of Eu(3+) doping, there is a reduction in Eu(3+) emission intensity for core-shell nanoparticles compared to that of core nanoparticles, and this has been attributed to the concentration dilution effect. Energy transfer from the host to Eu(3+) increases with increase of crystallinity. 相似文献
38.
Mahalingam V Sudarsan V Munusamy P van Veggel FC Wang R Steckl AJ Raudsepp M 《Small (Weinheim an der Bergstrasse, Germany)》2008,4(1):105-110
Bright blue-light emission at 410 nm is observed from Mg(2+)-doped GaN nanoparticles prepared by the nitridation of Ga(2)MgO(4) nanoparticles at 950 degrees C. The sintering of these nanoparticles during high-temperature nitridation was prevented by mixing the Ga(2)MgO(4) precursor nanoparticles with La(2)O(3) as an inert matrix before the nitridation process. The Mg(2+)-doped GaN nanoparticles were isolated from the matrix by etching with 10 % nitric acid. The Mg(2+)-doped GaN nanoparticles were characterized by photoluminescence, atomic force microscopy, X-ray diffraction, and IR analyses. 相似文献
39.
Corrosion of Borosilicate Glasses Subjected to Aggressive Test Conditions: Structural Investigations 下载免费PDF全文
Vidya S. Thorat Raman K. Mishra Sudarsan V. Kumaran Amar Kumar Rajesh K. Vatsa Chetan P. Kaushik Avesh K. Tyagi 《Journal of the American Ceramic Society》2016,99(10):3251-3259
Sodium borosilicate (NBS) and barium sodium borosilicate (BBS) glasses, used for immobilization of high‐level nuclear waste with compositions (SiO2)0.477(B2O3)0.239(Na2O)0.170(TiO2)0.023(CaO)0.068(Al2O3)0.023 and (SiO2)0.482(B2O3)0.244(Na2O)0.220(BaO)0.054 were subjected leaching experiments under hydrothermal conditions in an autoclave at 200°C for different time durations. Morphological and structural transformations associated with leaching, have been monitored with techniques like XRD, SEM, solid‐state nuclear magnetic resonance. XRD and SEM along with NMR studies have confirmed that, upon leaching, formation of an aluminosilicate phase, Zeolite‐P (Na6Al6Si10O32·12H2O), occurs with NBS glass. BBS glass upon subjecting to the same conditions leads to formation of multiple amorphous phases having Q4 (silica rich phase) and Q3 structural units of Silicon along with structurally modified residual glass. Upon leaching BO3 structural units preferentially get released from BBS glass. Comparison of results with international simple glass confirmed that, for the latter, mass loss rates are one order of magnitude lower. 相似文献
40.