全文获取类型
收费全文 | 1438篇 |
免费 | 108篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 41篇 |
综合类 | 3篇 |
化学工业 | 364篇 |
金属工艺 | 38篇 |
机械仪表 | 62篇 |
建筑科学 | 67篇 |
矿业工程 | 2篇 |
能源动力 | 118篇 |
轻工业 | 117篇 |
水利工程 | 9篇 |
石油天然气 | 15篇 |
无线电 | 122篇 |
一般工业技术 | 267篇 |
冶金工业 | 61篇 |
原子能技术 | 5篇 |
自动化技术 | 266篇 |
出版年
2024年 | 3篇 |
2023年 | 31篇 |
2022年 | 52篇 |
2021年 | 87篇 |
2020年 | 74篇 |
2019年 | 89篇 |
2018年 | 119篇 |
2017年 | 121篇 |
2016年 | 93篇 |
2015年 | 80篇 |
2014年 | 103篇 |
2013年 | 152篇 |
2012年 | 89篇 |
2011年 | 107篇 |
2010年 | 71篇 |
2009年 | 70篇 |
2008年 | 44篇 |
2007年 | 28篇 |
2006年 | 24篇 |
2005年 | 19篇 |
2004年 | 11篇 |
2003年 | 14篇 |
2002年 | 9篇 |
2001年 | 11篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1976年 | 2篇 |
排序方式: 共有1557条查询结果,搜索用时 15 毫秒
991.
Sriraj Srinivasan George Kalfas Violeta I. Petkovska Christopher Bruni Michael C. Grady Masoud Soroush 《应用聚合物科学杂志》2010,118(4):1898-1909
This article presents an experimental study of the spontaneous thermal homopolymerization of methyl acrylate (MA) and n‐butyl acrylate (nBA) in the absence of any known added initiators at 120 and 140°C in a batch reactor. The effects of the solvent type, oxygen level, and reaction temperature on the monomer conversion and polymer average molecular weights were investigated. Three solvents, dimethyl sulfoxide (DMSO; polar, aprotic), cyclohexanone (polar, aprotic), and xylene (nonpolar) were used. The spontaneous thermal polymerization of MA and nBA in DMSO resulted in a lower conversion and higher average molecular weights in comparison to polymerization in cyclohexanone and xylene under the same conditions. The highest final conversion of both monomers was obtained in cyclohexanone. The high polymerization rate in cyclohexanone was most likely due to an additional initiation mechanism where cyclohexanone complexed with the monomer to generate free radicals. Bubbling air through the mixture led to a higher monomer conversion during the early stage of the polymerization and a lower polymer average molecular weight in xylene and cyclohexanone; this indicated the existence of a distinct behavior between the air‐ and nitrogen‐purged systems. Matrix‐assisted laser desorption/ionization time‐of‐flight analysis of the polymer samples taken from nitrogen‐bubbled batches did not reveal fragments from initiating impurities. On the basis of the identified families of peaks, monomer self‐initiation is suggested as the principal mode of initiation in the spontaneous thermal polymerization of MA and nBA at temperatures above 100°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
992.
Sayed Siavash Madaeni Masoud Rahimi Mahdiah Abolhasani 《Korean Journal of Chemical Engineering》2010,27(1):206-213
The accumulation of deposited layer on membrane surface in cross-flow microfiltration was investigated. This study provides
a basis for elucidation of the membrane segments with superior tendency for cake deposition due to fouling. A commercially
available GVWP membrane was fouled with a colored (blue indigo suspension in water) feed. The deposition pattern or fouling
tendency was obtained using a digital camera, scanning electron microscope (SEM) and image analysis. The effects of feed concentration,
transmembrane pressure and cross-flow velocity on cake deposition were investigated. In the early stages of the filtration
trials, cake deposition was increased from the commencement portion (feed inlet) towards the furthermost part (concentrate
outlet) of the membrane surface. However, at the completion of filtration, no pronounced difference was realized between cake
deposition in the median and end parts of the membrane. Computational fluid dynamics (CFD) modeling of the membrane was carried
out to predict the fouling behavior in various segments of the membrane at different operating conditions. The results of
CFD modeling are in acceptable agreement with the experimental data. Accomplishment of the membrane sections with higher tendency
for accumulation of foulants may provide a basis for manipulation of conditions to diminish the buildup of fouling deposition
in the proposed segments. This results in lower cake deposition on vital parts to minimize the overall fouling. 相似文献
993.
The construction and performance characteristics of PVC membrane (PME) and coated graphite (CGE) Fe3+ ion selective electrodes based on 1-phenyl-3-pyridin-2-yl-thiourea (PPT) are described. The electrodes exhibit a Nernstian slope of 20.2 ± 0.8 (CGE) and 19.9 ± 0.4 (PME) mV decade−1 of activity in Fe3+ ion over a wide concentration range from 3.0 × 10−7 to 1.0 × 10−2 M for CGE and 6.9 × 10−7 to 1.0 × 10−2 M Fe3+ for PME. The lower detection limits by CGE and PME are 2.0 × 10−7 and 3.9 × 10−7 M, respectively, in the pH range of 1.8-5.6 for PME and 1.8-5.8 for CGE with a fast response time (<10 s). The standard electrode potentials were determined at different temperatures and used to calculate the isothermal coefficient of the PME. The PME showed the working temperature range of 22-55 °C with isothermal temperature coefficient of 1.33 × 10−3 V/°C and it was also used in non-aqueous solvents. The electrodes were successfully applied to determine iron(III) in water samples. 相似文献
994.
Fast and clean functionalization of carbon nanotubes by dielectric barrier discharge plasma in air compared to acid treatment 总被引:1,自引:0,他引:1
Masoud Vesali Naseh Yadollah Mortazavi Fathollah Pourfayaz Morteza Maghrebi 《Carbon》2010,48(5):1369-1379
Multi-walled carbon nanotubes (MWCNTs) have been functionalized by a dielectric barrier discharge plasma in air and compared to those functionalized in HNO3. The MWCNTs were prepared by chemical vapor deposition of xylene using ferrocene as a catalyst at 850 °C. Air oxidation followed by acid treatment was used to purify the MWCNTs, which were then annealed in helium. The MWCNTs were functionalized in air in a plasma reactor at room temperature. Quantitative analyses of gases evolved during the temperature programmed desorption of the functionalized nanotubes were carried out using Fourier transform infrared spectroscopy and gas chromatography. The influence of plasma parameters, including power in the range of 8-90 W and treatment time in the range of 1-9 min, on the number of the functional groups was investigated. It is shown that the extent of functionalization increases with increasing discharge power, provided that the exposure time of the MWCNTs in the plasma atmosphere does not exceed a certain period of time. Compared to acid treatment, plasma functionalization offers the advantages of much shorter treatment time, and produces less damage. 相似文献
995.
996.
Hamideh Haghjoo Fatemeh Sadat Sangsefidi Masoud Salavati-Niasari 《Journal of Materials Science: Materials in Electronics》2018,29(10):8002-8009
Pure Pb2SiO4 nanostructures were fabricated using amines as alkaline agents by sol–gel method and characterized via X-ray powder diffraction (XRD), Fourier-transformed infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), and Energy-dispersive X-ray spectroscopy (EDS). The average crystallite size of the products in presence and absence of the alkaline agent in the reaction was calculated about 18 and 34 nm by XRD technique, respectively. The type of alkaline agent was evaluated to achieve the optimized nanostructure. The results showed that the ethylenediamine as an alkaline agent has a better performance than the other alkaline agents (ammonia, triethylenetetramine, and tetraethylenepentamine). Optical property of optimized nanostructure was studied by diffuse reflectance spectroscopy (DRS) and its band gap was estimated to about 3.3 eV. It is the first time that photo-catalytic behavior of Pb2SiO4 nanostructure was investigated. The photo-catalytic performance of optimized Pb2SiO4 nanostructure was evaluated in the presence of various concentrations of Reactive Red198 and Reactive Orange16 dyes. The degradation percentage of dyes in various concentrations (5, 7, and 9 ppm) was obtained for Reactive Red198 and Reactive Orange16 about 100, 57, and 52% and also 100, 52, and 42% after 75 min ultraviolet irradiation, respectively. At 5 ppm concentration, Reactive Orange16 pollutant destruction was faster than Reactive Red198. 相似文献
997.
998.
999.
Sahar Zinatloo-Ajabshir Zahra Salehi Masoud Salavati-Niasari 《Ceramics International》2018,44(4):3873-3883
An effective and simple route is developed for production of Dy2Ce2O7 nanostructures by applying juice of Punica granatum as fuel and metal nitrates. Juice of Punica granatum has for the first time been exploited as a new fuel for simple synthesis of various structures of Dy2Ce2O7 in terms of shape, photocatalytic efficiency and particle size at different time and temperature for production. TEM, Raman, DRS, XRD, FESEM and EDS are exploited for study and characterization the obtained nano-sized structures of Dy2Ce2O7. Photocatalytic efficiencies have been evaluated with destruction of erythrosine and methylene blue pollutants under visible illumination over the various structures of Dy2Ce2O7. Results clearly demonstrated that the nano-sized structures of Dy2Ce2O7 obtained by application of juice of Punica granatum as new fuel at 450 °C for 4 h revealed excellent photocatalytic efficiency for the destruction of erythrosine and methylene blue pollutants. 相似文献
1000.
Ali Salehabadi Masoud Salavati-Niasari Tahereh Gholami 《International Journal of Hydrogen Energy》2017,42(22):15308-15318
A green synthesis method, solution combustion, were performed to synthesize BaAl2O4/BaCO3 nanoparticles by using stoichiometric amount of cations, Ba2+ and Al3+, in rational fraction of a fuel (maltose). Single fuel led to the formation of combustion reaction required further annealing at 700 °C in order to achieve pure crystals. The average crystallite sizes of the BaAl2O4/BaCO3 nanopowders were obtained about 36 nm using modified Scherrer equation. In order to improve the electrochemical hydrogen storage capacity of BaAl2O4/BaCO3 nanoparticles, a novel admixture was designed by introducing copper phthalocyanine (CuPc) into an inorganic phase. The reaction profiles of BaAl2O4/BaCO3-CuPc nanocomposites were confirmed by FTIR analysis. The structural and elemental analysis were confirmed the formation of nanocomposites. Morphological analysis confirmed the nanoscale formation of the host material. In addition, TEM results clearly confirmed the morphology of BaAl2O4/BaCO3 sample and its nanocomposites. The Band gap energy was calculated for host, CuPc and its respective nanocomposites using Tauc method obtained at 4.95, 2.10 and 2.54/4.89 eV, respectively. Electrochemical performances of the materials were confirmed a large Ipa for BaAl2O4/BaCO3-CuPc nanocomposites as compare to the host materials. This was directly reflected in hydrogen storage capacities of the materials (900 mA h/g discharge capacity for BaAl2O4/BaCO3 (~3.17%) and >1500 mA h/g for BaAl2O4/BaCO3-CuPc nanocomposites (~5.3%)). 相似文献