全文获取类型
收费全文 | 151篇 |
免费 | 9篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 54篇 |
机械仪表 | 6篇 |
建筑科学 | 4篇 |
能源动力 | 2篇 |
轻工业 | 24篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 13篇 |
一般工业技术 | 26篇 |
冶金工业 | 6篇 |
自动化技术 | 20篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 7篇 |
2020年 | 5篇 |
2019年 | 14篇 |
2018年 | 12篇 |
2017年 | 14篇 |
2016年 | 12篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 16篇 |
2012年 | 8篇 |
2011年 | 16篇 |
2010年 | 13篇 |
2009年 | 3篇 |
2008年 | 3篇 |
2007年 | 4篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有160条查询结果,搜索用时 15 毫秒
71.
The mathematical equations for heat transfer between a flowing fluid and both slab-shaped and spherical particles with intraparticle conduction in a fixed bed, are numerically solved using the method of lines. The solution for spherical particles was used to confirm previous results for zero and non-zero Biot numbers. Conditions are identified under which heat transfer to beds of slabs should not be approximated by available solutions for spheres. 相似文献
72.
73.
Catalytic polymerization of catechol was performed employing the cationic porphyrin and horseradish peroxidase (HRP) as catalysts. The obtained results demonstrate that the cationic metalloporphyrin is a more-efficient catalyst than the HRP in the catechol polymerization. The oxidative polymerization was carried out in the presence of polystyrene sulfonate (PSS) as a template. According to TGA data, poly(catechol) that is synthesized by porphyrin catalyst exhibits more thermal stability than the enzymatic catalyzed product. The GPC indicate higher molecular weight of polymer synthesized by porphyrin as a catalyst. Cyclic voltammetry measurements show that the synthesized polymers have convenient electroactivity. The poly(catechol) and its methyl and methoxy derivatives that are synthesized by porphyrin catalyst show low electrical conductivity. 相似文献
74.
Dependence of Semiconductor to Metal Transition of VO2(011)/NiO{100}/MgO{100}/TiN{100}/Si{100} Heterostructures on Thin Film Epitaxy and Nature of Strain 下载免费PDF全文
Reza Bayati Roya Molaei Fan Wu Jagdish Narayan Sergey Yarmolenko 《Journal of the American Ceramic Society》2015,98(4):1201-1208
We have studied semiconductor to metal transition (SMT) characteristics of VO2(011) thin films integrated epitaxially with Si(100) through NiO{001}/MgO{001}/TiN{001} buffer layers and correlated with the details of epitaxy and nature of residual stresses and strains across the VO2/NiO interface. Thin film epitaxy at both room and elevated temperatures is studied in detail by electron microscopy and in situ high‐temperature X‐ray diffraction techniques. The epitaxial relationship across the interface between monoclinic VO2 and NiO is determined to be (011)VO2||{100}NiO and [01]VO2||[001]NiO at room temperature. The epitaxial alignment at the temperature of growth where tetragonal VO2 is stable is determined as: (110)VO2||{100}NiO and [001]VO2||[100]NiO. A cube‐on‐cube crystallographic alignment is established across the NiO{100}/MgO{100}/TiN{100}/Si{100} interfaces. The misfit strains across the VO2/NiO interface at the growth temperature are calculated and the mechanism of strain relaxation is discussed. The out‐of‐plane orientation is found to be relaxed in both monoclinic and tetragonal states of VO2. It is shown that a compressive strain of 31.65% along the [001] direction of tetragonal VO2 is fully relaxed via matching of multiple domains. However, a small tensile misfit strain of about 5% along [10] direction cannot relax and remains in the lattice. This tensile residual strain leads to a compressive strain along [001] axis which, in turn, results in an SMT temperature slightly lower than that of freestanding strain‐free VO2. SMT characteristics of VO2(011) epilayers are assessed where an amplitude of near five orders of magnitude, and a hysteresis of less than 3.6 °C are obtained. This study introduces VO2/NiO thin film heterostructure integrated with silicon as a promising candidate for multifunctional devices with novel characteristics where a combination of sensing, manipulation, and response functions is needed. 相似文献
75.
Mahtab Pourzaki Roya Kavkhani Abbas Kianvash Abdollah Hajalilou 《Ceramics International》2019,45(5):5710-5716
Co-Mg ferrites, (x?=?0.0, 0.2, 0.4, 0.6, 0.8 and 1.0, 0?<?y?<?0.34 and 0?<?z?<?0.67), were synthesized via a standard ceramic route, and the structural, morphological, magnetic properties and transmission parameter of the samples were studied. The thermal behavior of the ground powder was characterized using a differential thermal analysis technique (DTA). The XRD patterns proved the formation of single phase Mg-ferrite in the samples with "x" contents varying from 0.0 to 0.8. The sample with x?=?1.0 showed two phases: a spinel Mg-ferrite and a secondary (Co,Mg)O phase. The lattice parameter and crystallite size of the samples increased remarkably by increasing the x content. The SEM images revealed that Co substitution in Mg ferrite at x?=?0.2 causes the particle growth, but their growth was not significant until x?=?0.8. For x?=?1.0, a remarkable particle growth was again observed. A maximum bulk density of 4.94?g/cm3 was obtained for x?=?0.8. Magnetic properties of the sintered samples showed an increase in coercive force up to 113?Oe by increasing Co substitution up to x?=?1.0. Saturation magnetization reached a maximum value of ~45.40?emu/g at x?=?0.8. Studying the microwave transmission behavior of the samples, using a vector network analyzer (VNA), indicated that by increasing Co, the transmission loss was reduced from ??15?dB for x?=?0.0 to less than ??10?dB for x?=?0.8 in the frequency range of 8–12?GHz. 相似文献
76.
Abolfazl Yazdanpanah Reza Kamalian Fathollah Moztarzadeh Masoud Mozafari Roya Ravarian Lobat Tayebi 《Ceramics International》2012,38(6):5007-5014
In this research, the replacement effects of bioactive glass (BG) by nanocrystalline forsterite (NF) on the biomineralization, microstructural and mechanical properties of BG-based nanocomposites were investigated. The hybrid nanocomposites with different NF contents (0, 10, 20, and 30 wt%) were prepared from the nanopowders by means of conventional cold pressing method. Surprisingly, the addition of NF provided redundant mechanisms to improve the toughness of the BG matrix without deteriorating its biomineralization properties. In addition, the resulting enhancement in the fracture toughness, observed for the first time in highly bioactive BG/NF nanocomposites, indicated the potential of the prepared nanocomposites as advanced biomaterials for load-bearing bone tissue engineering applications. 相似文献
77.
Simple synthesis of silver doped TiO2 nanostructured layers by micro arc oxidation process is reported for the first time. The layers consisted of anatase and rutile phases whose characteristic XRD-peaks shifted toward lower diffraction angles when compared to the pure micro arc oxidized TiO2 layers. Silver-doping was confirmed by XPS technique. The anatase phase crystalline size was determined as 27.6 and 21.8 nm for the layers grown under the voltages of 350 and 500 V. Employing a UV-Vis spectrophotometer, a red shift in the absorption edge of the layers was observed when silver was incorporated into the titania lattice. 相似文献
78.
Polymeric materials are prone to creep loading. This paper is aimed to study the effect of multi-walled carbon nanotubes (MWCNTs) on creep behavior of adhesively bonded joints. Neat and MWCNTs-reinforced adhesively bonded joints were manufactured and tested under creep loading at elevated temperatures. Two MWCNT weight percentages of 0.1 and 0.3 were used for reinforcing the single lap joints (SLJs) and the joints were tested at different temperature and load levels. The results showed that 0.1 wt% of MWCNTs resulted maximum improvements in creep behavior of adhesive joints. Adding 0.1 wt% of MWCNTs into the adhesive layer caused maximum reductions of 57%, 60% and 47% in the steady-state creep rates of the joints tested at 30, 40 and 50°C, respectively. Furthermore, 0.1 wt% of MWCNTs resulted maximum reductions of 29%, 33% and 37% in the creep strains corresponding to a specific creep loading time and maximum reductions of 23%, 45% and 49% in the elastic strains corresponding to the time at which creep loading started. 相似文献
79.
Shahram Shoeibi Maryam Amirahmadi Hossein Rastegar Roya Khosrokhavar Amin Mousavi Khaneghah 《Journal of food science》2013,78(5):T792-T796
It is important to have a reliable method to analyze pesticides in tea, a beverage commonly consumed in Iran. A validated method was developed for the determination of 20 pesticides in tea based on QuEChERS sample preparation and capillary gas chromatography‐quadrupole mass spectrometry in selective ion monitoring mode (GC‐MS/SIM) using triphenyl methane (TPM) solution as an internal standard. We used fortified, extracted, and cleaned‐up tea samples instead of calibration standards for quantitation, which substantially reduced adverse matrix‐related effects and negative recovery affected by graphite carbon black (GCB) on pesticide analysis. The recovery of pesticides at 3 concentration (40, 60, and 240 ng/g) ranged from 79.5% to 111.4% (n = 3). The method had acceptable repeatability with RSDr < 20%. The limits of quantification (LOQ) for all pesticides were ≤20 ng/g. The analytical results of the proposed method were in good agreement with proficiency test results (FAPAS, 19116). The recoveries and repeatabilities were in accordance with the criteria set by SANCO Guideline. The validated method was suitable for the analysis of pesticides in tea. 相似文献
80.
Investigating the production and properties of Ag/TiO2/PP antibacterial nanocomposite filament yarns
In this research, investigating the possibility of producing, processing and also characterization of antibacterial organic/inorganic nanocomposite polypropylene fiber has been presented. For this purpose, PP powder and inorganic nanocomposite filler were mixed using a twin screw extruder and modified granule was produced. After producing as-spun filament yarns by a pilot plant melt spinning machine at the take-up speed of 2000 m/min, samples were drawn, textured and finally weft knitted. Physical and structural properties of as-spun and drawn yarns with constant and variable draw ratios were investigated. The experimental results revealed that the crystallinity reduction of modified as-spun yarns could be compensated by drawing process. Tensile properties of modified drawn yarns with the variable draw ratio were higher than the pure PP, whereas the inverse observation was noticed in the case of constant draw ratio. The investigation of antimicrobial activity showed a high percentage of biostatic efficiency on the modified samples. 相似文献