全文获取类型
收费全文 | 3847篇 |
免费 | 261篇 |
国内免费 | 22篇 |
专业分类
电工技术 | 50篇 |
综合类 | 32篇 |
化学工业 | 1070篇 |
金属工艺 | 101篇 |
机械仪表 | 139篇 |
建筑科学 | 81篇 |
能源动力 | 275篇 |
轻工业 | 471篇 |
水利工程 | 41篇 |
石油天然气 | 29篇 |
无线电 | 386篇 |
一般工业技术 | 740篇 |
冶金工业 | 158篇 |
原子能技术 | 38篇 |
自动化技术 | 519篇 |
出版年
2024年 | 15篇 |
2023年 | 94篇 |
2022年 | 216篇 |
2021年 | 298篇 |
2020年 | 197篇 |
2019年 | 203篇 |
2018年 | 270篇 |
2017年 | 227篇 |
2016年 | 236篇 |
2015年 | 163篇 |
2014年 | 234篇 |
2013年 | 378篇 |
2012年 | 279篇 |
2011年 | 266篇 |
2010年 | 163篇 |
2009年 | 132篇 |
2008年 | 79篇 |
2007年 | 65篇 |
2006年 | 56篇 |
2005年 | 40篇 |
2004年 | 47篇 |
2003年 | 35篇 |
2002年 | 35篇 |
2001年 | 35篇 |
2000年 | 21篇 |
1999年 | 20篇 |
1998年 | 50篇 |
1997年 | 32篇 |
1996年 | 29篇 |
1995年 | 26篇 |
1994年 | 28篇 |
1993年 | 22篇 |
1992年 | 14篇 |
1991年 | 15篇 |
1990年 | 10篇 |
1989年 | 17篇 |
1988年 | 18篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 2篇 |
排序方式: 共有4130条查询结果,搜索用时 0 毫秒
101.
Uncrosslinked and chemically crosslinked ethylene‐vinyl acetate copolymers (EVAs) with 5–25 volume percentages of zeolite were prepared in a melt‐mixing process and then compression‐molded on a hot‐press machine according to standard test specifications. The mechanical properties measured by tensile test showed a reduction in tensile strength and elongation at break with increasing zeolite content. However, an increasing trend was observed for tensile modulus with addition of zeolite. Experimental results for ultimate stress were compared with those from Pukanszky equation. The experimental data showed a good fit to the Pukanszky model. The improvement in the interfacial interaction for crosslinked composites was also confirmed by this model. Morphological changes of EVA/zeolite composites were analyzed by scanning electron microscopy (SEM). The fractured surface of the composites indicated more complex morphology at higher zeolite loading. The influence of crosslinking induced by 2 wt% of dicumyl peroxide on the properties of EVA/zeolite composites was also investigated. The crosslinked composites showed better tensile properties than the uncrosslinked ones, a result which might be an indication of enhanced interaction between the EVA and zeolite. Density measurements, gel content determinations, and Fourier transform infrared analyses were also performed to evaluate the crosslink content of the composites. The changes in the properties of chemically crosslinked EVA/zeolite composites were observed. Meanwhile, SEM micrographs of the crosslinked EVA/zeolite composites showed better interfacial strength between zeolite and the EVA matrix as compared to that of the uncrosslinked composites. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers 相似文献
102.
Khamirul Amin Matori Loy Chee Wah Mansor Hashim Ismayadi Ismail Mohd Hafiz Mohd Zaid 《International journal of molecular sciences》2012,13(12):16812-16821
We report on a recycling project in which α-Al2O3 was produced from aluminum cans because no such work has been reported in literature. Heated aluminum cans were mixed with 8.0 M of H2SO4 solution to form an Al2(SO4)3 solution. The Al2(SO4)3 salt was contained in a white semi-liquid solution with excess H2SO4; some unreacted aluminum pieces were also present. The solution was filtered and mixed with ethanol in a ratio of 2:3, to form a white solid of Al2(SO4)3·18H2O. The Al2(SO4)3·18H2O was calcined in an electrical furnace for 3 h at temperatures of 400–1400 °C. The heating and cooling rates were 10 °C/min. XRD was used to investigate the phase changes at different temperatures and XRF was used to determine the elemental composition in the alumina produced. A series of different alumina compositions, made by repeated dehydration and desulfonation of the Al2(SO4)3·18H2O, is reported. All transitional alumina phases produced at low temperatures were converted to α-Al2O3 at high temperatures. The X-ray diffraction results indicated that the α-Al2O3 phase was realized when the calcination temperature was at 1200 °C or higher. 相似文献
103.
Georgios Papadopoulos Hanna Kurniawati Ahmed Shafeeq Bin Mohd Shariff Liang Jie Wong Nicholas M. Patrikalakis 《野外机器人技术杂志》2014,31(2):225-244
Over the past 10 years, significant scientific effort has been dedicated to the problem of three‐dimensional (3‐D) surface reconstruction for structural systems. However, the critical area of marine structures remains insufficiently studied. The research presented here focuses on the problem of 3‐D surface reconstruction in the marine environment. This paper summarizes our hardware, software, and experimental contributions on surface reconstruction over the past few years (2008–2011). We propose the use of off‐the‐shelf sensors and a robotic platform to scan marine structures both above and below the waterline, and we develop a method and software system that uses the Ball Pivoting Algorithm (BPA) and the Poisson reconstruction algorithm to reconstruct 3‐D surface models of marine structures from the scanned data. We have tested our hardware and software systems extensively in Singapore waters, including operating in rough waters, where water currents are around 1–2 m/s. We present results on construction of various 3‐D models of marine structures, including slowly moving structures such as floating platforms, moving boats, and stationary jetties. Furthermore, the proposed surface reconstruction algorithm makes no use of any navigation sensor such as GPS, a Doppler velocity log, or an inertial navigation system. 相似文献
104.
Zahid Hussain Shar Mary T. Fletcher Gul Amer Sumbal Syed Tufail Hussain Sherazi Cindy Giles Muhammad Iqbal Bhanger 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2016,33(5):849-860
This work reports the application of banana peel as a novel bioadsorbent for in vitro removal of five mycotoxins (aflatoxins (AFB1, AFB2, AFG1, AFG2) and ochratoxin A). The effect of operational parameters including initial pH, adsorbent dose, contact time and temperature were studied in batch adsorption experiments. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and point of zero charge (pHpzc) analysis were used to characterise the adsorbent material. Aflatoxins’ adsorption equilibrium was achieved in 15 min, with highest adsorption at alkaline pH (6–8), while ochratoxin has not shown any significant adsorption due to surface charge repulsion. The experimental equilibrium data were tested by Langmuir, Freundlich and Hill isotherms. The Langmuir isotherm was found to be the best fitted model for aflatoxins, and the maximum monolayer coverage (Q0) was determined to be 8.4, 9.5, 0.4 and 1.1 ng mg?1 for AFB1, AFB2, AFG1 and AFG2 respectively. Thermodynamic parameters including changes in free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were determined for the four aflatoxins. Free energy change and enthalpy change demonstrated that the adsorption process was exothermic and spontaneous. Adsorption and desorption study at different pH further demonstrated that the sorption of toxins was strong enough to sustain pH changes that would be experienced in the gastrointestinal tract. This study suggests that biosorption of aflatoxins by dried banana peel may be an effective low-cost decontamination method for incorporation in animal feed diets. 相似文献
105.
Anum Kayani Muhammad Asim Raza Arsalan Raza Tajamal Hussain Muhammad Sarfraz Akram Aneela Sabir Atif Islam Bilal Haider Rafi Ullah Khan Sang Hyun Park 《International journal of molecular sciences》2021,22(5)
Chitosan and polyethylene glycol (PEG-600) membranes were synthesized and crosslinked with 3-aminopropyltriethoxysilane (APTES). The main purpose of this research work is to synthesize RO membranes which can be used to provide desalinated water for drinking, industrial and agricultural purposes. Hydrogen bonding between chitosan and PEG was confirmed by displacement of the hydroxyl absorption peak at 3237 cm−1 in pure chitosan to lower values in crosslinked membranes by using FTIR. Dynamic mechanical analysis revealed that PEG lowers Tg of the modified membranes vs. pure chitosan from 128.5 °C in control to 120 °C in CS-PEG5. SEM results highlighted porous and anisotropic structure of crosslinked membranes. As the amount of PEG was increased, hydrophilicity of membranes was increased and water absorption increased up to a maximum of 67.34%. Permeation data showed that flux and salt rejection value of the modified membranes was increased up to a maximum of 80% and 40.4%, respectively. Modified films have antibacterial properties against Escherichia coli as compared to control membranes. 相似文献
106.
Norazah Mohd Suki 《Electronic Commerce Research》2013,13(4):477-491
Shopping on the Internet enables consumers to search for information on products or services and make purchases through direct interaction with online retailers. This study investigates consumer shopping behaviour on the Internet based on four aspects, i.e. the Internet marketing environment, product characteristics, familiarity, and promotional offers. The impact of influencing factors was checked by questionnaire survey, which was then processed and evaluated. Two hundred randomly selected respondents (students and employees in a public higher learning institution in the Federal Territory of Labuan, Malaysia) participated in the survey. Multiple regression analysis was used as a statistical measure to determine the most influential relationship aspect among a series of independent variables of consumer shopping on the Internet. The results revealed that familiarity has a great influence on consumer shopping on the Internet, followed by promotional offers. The assimilation of these aspects, and the empirical examination of the factors that influence consumer shopping on the Internet, advanced understanding of these constructs and their link to dynamic technology deployment for shopping. The paper suggests managerially actionable implications, and future research directions. 相似文献
107.
Shaik Abdul Subhani Karsh Ram Kumar Islam Mohiul Laskar Rabul Hussain 《Multimedia Tools and Applications》2022,81(2):2489-2516
Multimedia Tools and Applications - In the recent digitization era, image hashing is a key technology, including image recognition, authentication and manipulation detection, among many multimedia... 相似文献
108.
Mohd-Shafie Muhammad Luqman Kadir Wan Mohd Nasir Wan Lichter Horst Khatibsyarbini Muhammad Isa Mohd Adham 《Software and Systems Modeling》2022,21(2):717-753
Software and Systems Modeling - Model-based test case generation (MB-TCG) and prioritization (MB-TCP) utilize models that represent the system under test (SUT) for test generation and... 相似文献
109.
Mohammad Asim Mohd T. Paridah M. Chandrasekar Rao M. Shahroze Mohammad Jawaid Mohammed Nasir Ramengmawii Siakeng 《Iranian Polymer Journal》2020,29(7):625-648
Natural fiber-based composites are applied in many structural engineered products from civil constructions to automobile manufacturing due to the properties such as low density, high aspect ratio, biodegradability and ease to work. During the past decades such composites have been thoroughly studied for their mechanical properties and failure behavior and their properties compared with those of synthetic fiber-based composites. Other properties, such as the thermal behavior of natural fibers and composites, have also been studied because they determine the performance of their products possible. It deals with the effect of temperature on adhesive curing, effect of high temperature and fire damage during fabrication. Further, the thermal properties have equal importance in structural applications such as temperature transfer from end to end, load capacity at specific temperature, material behavior and dimensional stability at high temperature. In this respect the isothermal and non-isothermal thermogravimatric analyses are discussed and the improtance of glass transition temperature is studied during prepapration of composites to ensure their ultimate properties. Although there are several works that have been done on thermal behavior, especially thermogravimetric analysis of natural fibers and their composites, there is no review article available specially focused on natural fiber-based composites, hybrid composites, and nanocomposites. The aim of this review was to focus on the advances in the comprehension of thermogravimetric behavior of natural fibers and compare the effect of natural fibers as reinforced materials in polymer composites. 相似文献
110.
Noor-Ul-Ain Babar Yasir Faheem Joya Hassan Khalil Fayyaz Hussain Khurram Saleem Joya 《International Journal of Hydrogen Energy》2021,46(11):7885-7902
Developing only Fe derived bifunctional overall water splitting electrocatalyst both for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) while performing at low onset overpotential and with high catalytic stability is a rare instance. We present here the first demonstration of unique iron-oxide nanobeads (FeOx-NBs) based electrocatalyst executing both OER and HER with high activity. Thin-film electrocatalytic FeOx-NBs assembly is surface grown via simple spray coating (SC). The unique SC/FeOx-NBs propels OER initiating water oxidation just at 1.49 VRHE (η = 260 mV) that is the lowest observable onset potential for OER on simple Fe-oxide based catalytic films reported so far. Catalyst also reveals decently high HER activity and competent overall water splitting performance in the FeOx-NBs two-electrode system as well. Catalyst also presents stable kinetics, with promising high electrochemically active surface area (ECSA) of 1765 cm2, notable Tafel slopes of just 54 mV dec1? (OER) and 85 mV dec1? (HER), high exchange current density of 1.10 mA cm2? (OER), 0.58 mA cm2? (HER) and TOF of 74.29s1?@1.58VRHE, 262s1?@1.62VRHE (OER) and 82.5s1?@-0.45VRHE, 681s1?@-0.56VRHE (HER). 相似文献