全文获取类型
收费全文 | 694篇 |
免费 | 22篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 11篇 |
化学工业 | 180篇 |
金属工艺 | 22篇 |
机械仪表 | 12篇 |
建筑科学 | 7篇 |
能源动力 | 30篇 |
轻工业 | 22篇 |
水利工程 | 10篇 |
石油天然气 | 1篇 |
无线电 | 75篇 |
一般工业技术 | 151篇 |
冶金工业 | 103篇 |
原子能技术 | 4篇 |
自动化技术 | 93篇 |
出版年
2023年 | 8篇 |
2022年 | 13篇 |
2021年 | 24篇 |
2020年 | 27篇 |
2019年 | 21篇 |
2018年 | 20篇 |
2017年 | 9篇 |
2016年 | 21篇 |
2015年 | 10篇 |
2014年 | 16篇 |
2013年 | 41篇 |
2012年 | 29篇 |
2011年 | 31篇 |
2010年 | 24篇 |
2009年 | 24篇 |
2008年 | 32篇 |
2007年 | 28篇 |
2006年 | 15篇 |
2005年 | 29篇 |
2004年 | 17篇 |
2003年 | 12篇 |
2002年 | 8篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1999年 | 14篇 |
1998年 | 31篇 |
1997年 | 14篇 |
1996年 | 23篇 |
1995年 | 15篇 |
1994年 | 7篇 |
1993年 | 11篇 |
1992年 | 12篇 |
1991年 | 13篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 9篇 |
1985年 | 18篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1980年 | 2篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1973年 | 4篇 |
1972年 | 2篇 |
1971年 | 3篇 |
排序方式: 共有721条查询结果,搜索用时 296 毫秒
1.
Ajit Sharma Doan Van Thuan Thanh-Dong Pham Mai Hung Thanh Tung Nguyen Thi Thanh Truc Dai-Viet N. Vo 《化学工程与技术》2020,43(4):752-761
FeO-doped TiO2 nanoparticle photocatalysts were immobilized onto the surface of fibrous activated carbon (ACF) via a sol-gel process. As an adsorbent and photocatalyst, FeO-TiO2 on immobilized ACFs (FeO-TiO2/ACF) greatly improved the photocatalysis rate of hydrogen production as compared with pure TiO2 and ACF-TiO2 under UV irradiation and visible light. The addition of ACFs surface significantly reduced the photogenerated pairs of electrons-hole recombination, thereby promoting the photocatalysis action of doped photo-metal oxides of FeO-TiO2. Co-doping of FeO onto the lattice of the TiO2 approach can improve the absorption activity of visible light through photo-metal oxide of TiO2 and further enhance hydrogen production under visible light. The photocatalytic fabrics (FeO-TiO2/ACF) were effortlessly split out from the experimental solution for re-utilization and exhibited high stability even after five complete regeneration cycles. 相似文献
2.
3.
Effect of boron on the low-cycle fatigue behavior and deformation structure of INCONEL 718 at 650 °C
L. Xiao M. C. Chaturvedi D. L. Chen 《Metallurgical and Materials Transactions A》2004,35(11):3477-3487
Symmetrical push-pull low-cycle fatigue (LCF) tests were performed on INCONEL 718 (IN718) containing 12, 29, 60, and 100 ppm
B at 650 °C. The results showed that all the alloys experienced a relatively short period of initial cyclic hardening at low
strain amplitudes, followed by a regime of saturation or slightly continuous cyclic softening. The initial cyclic hardening
phase decreased with increasing strain amplitudes, and disappeared at the high strain amplitudes. A serrated flow was observed
in the plastic regions of cyclic stress-strain hysteresis loops. The saturated cyclic stress amplitude at a given strain amplitude
was highest for the alloy with 60 ppm B, and lowest for the alloy with 12 ppm B. The LCF lifetime increased with increasing
B concentration up to 60 ppm, and then decreased as the B content increased from 60 to 100 ppm. Fractographic analysis suggested
that the fracture mode changed from intergranular to transgranular cracking as the B concentration increased. The characteristic
deformation microstructures produced by LCF tests at 650 °C, examined via transmission electron microscopy, were regularly spaced arrays of planar deformation bands on {111} slip planes in all four
alloys. A ladderlike structure was observed in some local regions in the alloy with 12 ppm B. Heavily deformed planar deformation
bands were observed in the fatigued specimens with 100 ppm B. The mechanism of improvement in the LCF life of IN718 due to
B addition is discussed. 相似文献
4.
Some substituted coumarins have been synthesized by von-Pechmann condensation using SnCl2 · 2H2O (10 mol %) as catalyst in ethanolic medium. The reactions are simple, easy in handling and environmentally benign. 相似文献
5.
Lean philosophy: implementation in a forging company 总被引:2,自引:2,他引:0
Ajit Kumar Sahoo N. K. Singh Ravi Shankar M. K. Tiwari 《The International Journal of Advanced Manufacturing Technology》2008,36(5-6):451-462
This research addresses the implementation of lean philosophy in a forging company with a focus on radial forging production
flow lines. Here, the prime motive is to evolve and test several strategies to eliminate waste on the shop floor. In this
research, a systematic approach is suggested for the implementation of lean principles. This paper describes an application
of value stream mapping (VSM). Consequently, the present and future states of value stream maps are constructed to improve
the production process by identifying waste and its sources. Furthermore, Taguchi’s method of design of experiments is pursued
here to minimize the forging defects produced due to imperfect operating conditions. A noticeable reduction in set-up time
and work-in-process (WIP) inventory level is substantiated. Finally, we conclude with a discussion of managerial implications
and the future scope of research. 相似文献
6.
7.
8.
In this communication, the stability of the double-diffusive solar ponds with non-uniform temperature and salinity gradients has been investigated. This is a further generalization of our approach to this problem initiated in Ref. [7]. Using a stochastic approach, the linearized system of basic equations of motion is reduced to a single integro-differential equation. For convective motion, this equation reduces to a time-independent Schrödinger equation for a particle moving in a potential field ƒ(Z) characterized by the non-uniform temperature and salinity gradients. This equation can, in general, be solved (exactly or approximately depending on the form of the gradient profile) by methods commonly used in quantum mechanics.
In the Appendix, we show that, for a quadratic gradient profile, the above equation has an analytical solution similar to that obtained by Zangrando using numerical computations. 相似文献
9.
10.
Two processes, namely shrinkage and primary fragmentation are known to be the major causes of size reduction of wood during its devolatilization in a fluidized bed combustor. A simple phenomenological model incorporating these effects to compute the average char size at the end of devolatilization is proposed. Experiments are conducted in a bubbling fluidized bed combustor using wood having three different shapes namely, cylinder, cuboid and sphere, to measure the average char size at the end of devolatilization. The model prediction of average char size agrees with the measured values within a deviation of 15%. An experimental correlation is derived to determine the number of fragments and is used to estimate the mean char size. 相似文献