全文获取类型
收费全文 | 144篇 |
免费 | 9篇 |
国内免费 | 2篇 |
专业分类
化学工业 | 39篇 |
金属工艺 | 2篇 |
机械仪表 | 1篇 |
建筑科学 | 1篇 |
能源动力 | 11篇 |
轻工业 | 35篇 |
水利工程 | 2篇 |
石油天然气 | 3篇 |
无线电 | 13篇 |
一般工业技术 | 27篇 |
冶金工业 | 11篇 |
原子能技术 | 1篇 |
自动化技术 | 9篇 |
出版年
2023年 | 1篇 |
2022年 | 6篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 8篇 |
2018年 | 10篇 |
2017年 | 13篇 |
2016年 | 5篇 |
2015年 | 5篇 |
2014年 | 12篇 |
2013年 | 8篇 |
2012年 | 5篇 |
2011年 | 7篇 |
2010年 | 14篇 |
2009年 | 8篇 |
2008年 | 2篇 |
2007年 | 5篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2002年 | 2篇 |
1999年 | 2篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1994年 | 3篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有155条查询结果,搜索用时 31 毫秒
21.
Biodiesel production via transesterification of mustard oil with methanol using solid oxide catalyst derived from waste shell of Turbonilla striatula was investigated. The shells were calcined at different temperatures for 4 h and catalyst characterizations were carried out by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), Fourier transform infrared spectrometer (FT-IR), thermogravimetric analysis (TGA)/differential scanning calorimetry (DSC) and Brunauer-Emmett-Teller (BET) surface area measurements . Formation of solid oxide i.e. CaO was confirmed at calcination temperature of 800 °C. The effect of the molar ratio of methanol to oil, the reaction temperature, catalyst calcination temperature and catalyst amount used for transesterification were studied to optimize the reaction conditions. Biodiesel yield of 93.3% was achieved when transesterification was carried out at 65 ± 5 °C by employing 3.0 wt.% catalyst and 9:1 methanol to oil molar ratio. BET surface area indicated that the shells calcined in the temperature range of 700 °C-900 °C exhibited enhanced surface area and higher pore volume than the shells calcined at 600 °C. Reusability of the catalysts prepared in different temperatures was also investigated. 相似文献
22.
L. J. Konwar D. Deka 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2018,40(6):601-607
In the wake of increasing environmental constraints, this work is aimed at developing a catalyst purely prepared from waste biomass source as the raw material. The catalyst is investigated for its applicability in transesterification of vegetable oil with the objectives: (i) to use waste shells of mollusk as raw material for the preparation of activated carbon and CaO; (ii) to use it as heterogeneous catalyst in the transesterification of waste cooking oil; (iii) to optimize the different parameters affecting the transesterification reaction; and (iv) to study its reusability. Under optimized conditions it was observed that a conversion >90% was possible and the catalyst could be reused five times with a slight loss in activity. This study indicates that the biomass source could also be used as a potential raw material in the synthesis of environmentally benign catalysts. 相似文献
23.
This study was carried out to determine the phytochemical and antioxidant properties of two pigmented rice cultivars viz., Lingkang taker ame, Umling ame, and a non-pigmented rice Pungpo taker ame. Fourier transform infrared and high-performance liquid chromatography analysis of phenolic compounds were carried out for the rice cultivars. The highest level of total phenolic, anthocyanin, and scavenging activities were observed in Umling ame cultivar. Fourier transform infrared result of rice cultivars showed wide range of frequency (1131.60–3538.75 cm–1) which confirmed the presence of various phenolic compounds. Seven phenolic acids were detected in the rice cultivars. The highest value of salicylic acid (302.06 ± 0.01 mg/L), ferulic acid (17.21 ± 0.02 mg/L), apigenin (7.03 ± 0.01 mg/L), and gallic acid (0.98 ± 0.04 mg/L) were detected in Umling ame; whereas the highest value of quercetin (611.46 ± 0.01 mg/L) and caffeic acid (1.83 ± 0.01 mg/L) were found in Pungpo taker ame and Lingkang taker ame cultivars, respectively. Results revealed that the colored rice Umling ame showed higher phenolic content than other two rice cultivars Lingkang taker ame and Pungpo taker ame. 相似文献
24.
25.
Biplab K. Deka Ankita Hazarika Jisoo Kim Young‐Bin Park Hyung Wook Park 《国际能源研究杂志》2017,41(10):1397-1411
In the last decades, fuel scarcity and increasing pollution level pave the way for an extensive interest in alternatives to petroleum‐based fuels such as biodiesel, solar cells, lithium ion batteries, and supercapacitors. Among them, structural supercapacitors have been considered as promising candidates for automotive industries in present time. Herein, the use of carbon fiber‐based supercapacitors in automotive applications is reviewed. Carbon fiber is an excellent candidate for vehicle body applications, and its composites could be widely used in the development of supercapacitors that could provide both structural and energy storage functions. Different surface modification processes of the carbon fiber electrode to enhance the electrochemical as well as mechanical performances are discussed. The advantages of the glass fiber separator and its comparison with other types of dielectric media have been incorporated. The synthesis procedures of the multifunctional solid polymer electrolyte and its significance have been also elaborated. The fabrication process, component selection, limitations, and future challenges of these supercapacitors are briefly assimilated in this review. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
26.
27.
A micellar electrokinetic capillary chromatographic (MECC) method has been developed and optimised for the separation of 5-aminolaevulinic acid (ALA) and porphobilinogen (PBG). The running buffer consisted of a mixture of 20 mM sodium phosphate and 20 mM sodium borate containing 50 mM sodium dodecyl sulphate (SDS) adjusted to pH 9.5 with 1 M NaOH. The running voltage and temperature were 20-25 kV and 30 degrees C, respectively. The MECC method for the analysis of PBG is fast and simple and is useful for the screening of PBG in the urine of patients suspected to have acute intermittent porphyria (AIP), and for the confirmation of lead exposure by measuring red-cell ALA-dehydratase (ALA-D) activity with ALA as the enzyme substrate. 相似文献
28.
29.
The objective of an accident-mapping algorithm is to snap traffic accidents onto the correct road segments. Assigning accidents onto the correct segments facilitate to robustly carry out some key analyses in accident research including the identification of accident hot-spots, network-level risk mapping and segment-level accident risk modelling. Existing risk mapping algorithms have some severe limitations: (i) they are not easily ‘transferable’ as the algorithms are specific to given accident datasets; (ii) they do not perform well in all road-network environments such as in areas of dense road network; and (iii) the methods used do not perform well in addressing inaccuracies inherent in and type of road environment. The purpose of this paper is to develop a new accident mapping algorithm based on the common variables observed in most accident databases (e.g. road name and type, direction of vehicle movement before the accident and recorded accident location). The challenges here are to: (i) develop a method that takes into account uncertainties inherent to the recorded traffic accident data and the underlying digital road network data, (ii) accurately determine the type and proportion of inaccuracies, and (iii) develop a robust algorithm that can be adapted for any accident set and road network of varying complexity. In order to overcome these challenges, a distance based pattern-matching approach is used to identify the correct road segment. This is based on vectors containing feature values that are common in the accident data and the network data. Since each feature does not contribute equally towards the identification of the correct road segments, an ANN approach using the single-layer perceptron is used to assist in “learning” the relative importance of each feature in the distance calculation and hence the correct link identification. The performance of the developed algorithm was evaluated based on a reference accident dataset from the UK confirming that the accuracy is much better than other methods. 相似文献
30.
Numerical investigation of crack tip strain localization under cyclic loading in FCC single crystals
In this work, the crack tip strain localization in a face centered cubic single crystal subject to both monotonic and cyclic loading was investigated. The effect of constraint was implemented using T-stress and strain accumulation was studied for both isotropic and anisotropic elastic cases with the appropriate application of remote displacement fields in plane strain. Modified boundary layer simulations were performed using the crystal plasticity finite element framework. The consideration of elastic anisotropy amplified the effect of constraint level on stress and plastic strain fields near the crack tip indicating the importance of its use in fracture simulations. In addition, to understand the cyclic stress and strain behavior in the vicinity of the crack tip, combined isotropic and kinematic hardening laws were incorporated, and their effect on the evolution of yield curves and plastic strain accumulation were investigated. With zero-tension cyclic load, the evolution of plastic strain and Kirchhoff stress components showed differences in magnitudes between isotropic and anisotropic elastic cases. Furthermore, under cyclic loading, ratcheting was observed along the localized slip bands, which was shown to be affected by T-stress as well as elastic anisotropy. Negative T-stress increased the accumulation of plastic strain with number of cycles, which was further amplified in the case of elastic anisotropy. Finally, in all the cyclic loading simulations, the plastic strain accumulation was higher near the \(55^0 \) slip band. 相似文献