全文获取类型
收费全文 | 2537篇 |
免费 | 252篇 |
国内免费 | 23篇 |
专业分类
电工技术 | 54篇 |
综合类 | 9篇 |
化学工业 | 764篇 |
金属工艺 | 101篇 |
机械仪表 | 137篇 |
建筑科学 | 119篇 |
矿业工程 | 10篇 |
能源动力 | 173篇 |
轻工业 | 326篇 |
水利工程 | 36篇 |
石油天然气 | 34篇 |
无线电 | 192篇 |
一般工业技术 | 437篇 |
冶金工业 | 61篇 |
原子能技术 | 24篇 |
自动化技术 | 335篇 |
出版年
2024年 | 13篇 |
2023年 | 48篇 |
2022年 | 80篇 |
2021年 | 191篇 |
2020年 | 175篇 |
2019年 | 187篇 |
2018年 | 223篇 |
2017年 | 214篇 |
2016年 | 217篇 |
2015年 | 117篇 |
2014年 | 194篇 |
2013年 | 301篇 |
2012年 | 188篇 |
2011年 | 192篇 |
2010年 | 144篇 |
2009年 | 104篇 |
2008年 | 59篇 |
2007年 | 38篇 |
2006年 | 26篇 |
2005年 | 17篇 |
2004年 | 12篇 |
2003年 | 11篇 |
2002年 | 7篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1976年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有2812条查询结果,搜索用时 15 毫秒
171.
Babak Abbasi Seyed Taghi Akhavan Niaki 《The International Journal of Advanced Manufacturing Technology》2010,50(5-8):823-830
The capability analysis of production processes where there are more than one correlated quality variables is a complicated task. The problem becomes even more difficult when these variables exhibit nonnormal characteristics. In this paper, a new methodology is proposed to estimate process capability indices (PCIs) of multivariate nonnormal processes. In the proposed methodology, the skewness of the marginal probability distributions of the variables is first diminished by a root transformation technique. Then, a Monte Carlo simulation method is employed to estimate the process proportion of nonconformities (PNC). Next, the relationship between PNC and PCI is found, and finally, PCI is estimated using PNC. Several multivariate nonnormal distributions such as Beta, Weibull, and Gamma are taken into account in simulation experiments. A real-world problem is also given to demonstrate the application of the proposed procedure. The results obtained from both the simulation studies and the real-world problem show that the proposed method performs well and is able to estimate PCI properly. 相似文献
172.
Homam Naffakh Moosavy Mohammad-Reza Aboutalebi Seyed Hossein Seyedein Carlo Mapelli 《Journal of Materials Processing Technology》2013,213(11):1875-1884
The Scheil equation was used to model the solidification path, microsegregation of alloying elements in the interdendritic regions, solidification temperature ranges, and to predict the formation of secondary structures and the castability behavior of as-cast superalloys. 4 experimental alloys with pre-specified γ-Ti,Nb,Al,Mo composition containing different Nb, Ti and Al contents were designed using vacuum induction melting furnace. The produced as-cast superalloys were characterized using optical and scanning electron microscopy equipped with energy dispersive X-ray spectrometer and TG–DSC analysis. The experiments showed logic conformity to the modeling results. The model and experiment confirmed the highest segregation behavior for Ti and Nb. All the experimental superalloys indicated the remarkable tendency to form secondary eutectic structures at the last stages of solidification. Superalloy with chemical composition of γ-3.5%Mo,1.8%Al,4%Ti,2.9%Nb showed the shorter solidification temperature range and the best castability. 相似文献
173.
M. Ehteshamzadeh A.H. Jafari Esmaeel Naderi M.G. Hosseini 《Materials Chemistry and Physics》2009,113(2-3):986-993
In this investigation, attempts have been made to study the inhibitive effect of N,N′-ortho-phenylen acetyle acetone imine (S1) and 4-[(3-{[1-(2-hydroxy phenyl) methylidene] amino} propyl] ethanemidol]-1,3-benzenediol (S2) in the concentration range of 50–400 ppm for mild steel with two different microstructures resulted from two different heat treatments (annealed (A) and quenched and tempered (Q&T)) in 1 M hydrochloric acid by ac impedance spectroscopy. The tests were conducted in acid solutions in the absence and presence of different concentrations of S1 and S2 Schiff bases for both microstructures. A sole time constant was observed from Bode-phase angle plots in the presence of inhibitors which reveals that the action of inhibitors is through adsorption on the surface. The charge transfer resistance and inhibition efficiency increases with the increase in Schiff bases concentration for both microstructures. The perlite samples in the absence of inhibitors in 1 M hydrochloric acid indicated slightly less corrosion than martensite ones, which was because of more protective oxide layers. Furthermore in the presence of S1 and S2, these samples showed better adsorption than martensite one. Schiff base S1 showed a better inhibition against corrosion in comparison with S2. Both S1 and S2 adsorbed on steel surface according to a Langmuir adsorption isotherm model. The associated Gibbs free energies for S1 on both microstructures are more than S2. 相似文献
174.
175.
A. R. Moghadassi S. M. Hosseini B. Yasini E. Joudaki A. R. Fazlali 《Petroleum Science and Technology》2013,31(10):1036-1045
Abstract Optimization in the chemical and petroleum industry is gaining increased interest because of its importance in maintaining product quality and enhancing production levels while improving profit margins. In this article, simulation of the atmospheric distillation unit of an existing petroleum refinery is carried out. Optimization was performed on the prepared simulation through the use of a sequential quadratic programming approach (SQP). The objective function consisted of energy minimization and production level maximization. The results obtained from optimization were implemented on the real process and it was demonstrated that the suggested changes increased overhead production levels and maintained product quality. Furthermore, a net economical balance between the increment of overhead products and the energy consumption showed an energy savings in the refinery. 相似文献
176.
Ali Rafe Seyed M. A. Razavi 《International Journal of Food Science & Technology》2013,48(9):1924-1931
Effect of pH (4.5–7.5) and Ca2+ (0.01–0.5 m ) on gelation of single and mixed systems of 10% β‐lactoglobulin (BLG) and 1% basil seed gum (BSG) was investigated. The gelling point of BLG and BSG gels was strongly pH‐dependent, and stiffer gels formed at higher pH. The BLG gels were formed upon heating to 90 °C and reinforced on cooling to 20 °C; however, the gelation of BSG occurred at temperatures below 70 °C. By increasing Ca2+ concentration, storage modulus of BLG and BSG gels were increased, although pH had a greater effect than Ca2+. In contrast, mixed systems showed two distinct types of behaviour: BLG gel formation and BSG network, suggesting that phase‐separated gels were formed. In addition, higher strength was obtained for BLG‐BSG mixture at higher Ca2+ concentration. 相似文献
177.
The main aim of this article is studying the coupled sine-Gordon equations in nonlinear optics, which describe the propagation of an optical pulse in fibre waveguide. New exact solutions of the coupled sine-Gordon equations have been derived through the use of the well-organized modified Kudryashov method. 相似文献
178.
Jaber Jahanbin Sardroodi Seyed Masood Seyed Ahmadian Gholam Reza Pazuki Moayad Hossaini Sadr Mahdi Esmaili 《Calphad》2006
The osmotic coefficient of the solution, activity of the solvent and activity coefficient of the solute in solutions of 1- and 2-naphthol in methanol and ethanol have been measured by the isopiestic method. The experimental osmotic coefficient data were correlated using the Non-Random Two Liquid model (NRTL), the Non-Random Factor model (NRF), the two suffix Margules equation and a polynomial in terms of the molality of the solute. The models give reliable results for the correlation of the osmotic coefficient data. The activity coefficients of 1- and 2-naphthol were evaluated according to the considered methods using the parameters obtained by the correlation of osmotic coefficients. 相似文献
179.
This paper presents a software-based error detection scheme called enhanced committed instructions counting (ECIC) for embedded and real-time systems using commercial off-the-shelf (COTS) processors. The scheme uses the internal performance monitoring features of a processor, which provides the ability to count the number of committed instructions in a program. To evaluate the ECIC scheme, 6000 software induced faults are injected into a 32-bit Pentium® processor. The results show that the error detection coverage varies between 90.52% and 98.18%, for different workloads. 相似文献
180.
An investigation into the wear process of five polymers tested under different contact conditions is presented. Polymer pin on metal plate and metal pin on polymer plate configurations were used. The metal pin on polymer plate configuration gave significantly lower wear rates compared to that observed for the polymer pin on metal plate configuration. The results are discussed in terms of morphology of wear debris generated. 相似文献