全文获取类型
收费全文 | 3716篇 |
免费 | 67篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 71篇 |
综合类 | 4篇 |
化学工业 | 572篇 |
金属工艺 | 97篇 |
机械仪表 | 73篇 |
建筑科学 | 152篇 |
矿业工程 | 11篇 |
能源动力 | 64篇 |
轻工业 | 223篇 |
水利工程 | 30篇 |
石油天然气 | 16篇 |
无线电 | 328篇 |
一般工业技术 | 525篇 |
冶金工业 | 1049篇 |
原子能技术 | 25篇 |
自动化技术 | 549篇 |
出版年
2022年 | 26篇 |
2021年 | 33篇 |
2019年 | 29篇 |
2018年 | 39篇 |
2017年 | 38篇 |
2016年 | 46篇 |
2015年 | 40篇 |
2014年 | 69篇 |
2013年 | 193篇 |
2012年 | 101篇 |
2011年 | 154篇 |
2010年 | 105篇 |
2009年 | 100篇 |
2008年 | 171篇 |
2007年 | 119篇 |
2006年 | 121篇 |
2005年 | 117篇 |
2004年 | 112篇 |
2003年 | 94篇 |
2002年 | 102篇 |
2001年 | 72篇 |
2000年 | 71篇 |
1999年 | 88篇 |
1998年 | 185篇 |
1997年 | 108篇 |
1996年 | 91篇 |
1995年 | 74篇 |
1994年 | 90篇 |
1993年 | 68篇 |
1992年 | 77篇 |
1991年 | 46篇 |
1990年 | 67篇 |
1989年 | 48篇 |
1988年 | 48篇 |
1987年 | 49篇 |
1986年 | 42篇 |
1985年 | 51篇 |
1984年 | 50篇 |
1983年 | 47篇 |
1982年 | 53篇 |
1981年 | 45篇 |
1980年 | 42篇 |
1979年 | 37篇 |
1978年 | 39篇 |
1977年 | 40篇 |
1976年 | 51篇 |
1975年 | 27篇 |
1974年 | 36篇 |
1973年 | 34篇 |
1970年 | 23篇 |
排序方式: 共有3789条查询结果,搜索用时 15 毫秒
1.
H.W. Choi C.W. Jeon M.D. Dawson 《Photonics Technology Letters, IEEE》2004,16(1):33-35
The fabrication and performance of an InGaN light-emitting diode (LED) array based on a microring device geometry is reported. This design has been adopted in order to increase the surface area for light extraction and to minimize losses due to internal reflections and reabsorption. Electrical characteristics of these devices are similar to those of a conventional large-area LED, while the directed light extraction proves to be superior. In fact, these devices are found to be more efficient when operated at higher currents. This may be attributed to improved heat sinking due to the large surface area to volume ratio. The potential applications of these devices are also discussed. 相似文献
2.
Heng Zhang Jack Gromek Gayath W. Fernando Harris L. Marcus Sam Boorse 《Journal of Phase Equilibria》2002,23(3):246-248
The thermal equilibrium decomposition properties of the PdO-Pd system under oxygen partial pressures ranging from 0.1 to 1.0 atm in a total combined pressure of oxygen and nitrogen of 1.0 atm were investigated by means of thermal-gravimetric analyses. The phase diagram of Pd-PdO over the range of oxygen/nitrogen gas concentration was established. The decomposition temperature of PdO to Pd was found to increase with the partial pressure of oxygen. 相似文献
3.
4.
We develop a characterization for m-fault-tolerant extensions, and for optimal m-fault-tolerant extensions, of a complete multipartite graph. Our formulation shows that this problem is equivalent to an interesting combinatorial problem on the partitioning of integers. This characterization leads to a new procedure for constructing an optimal m-fault-tolerant extension of any complete multipartite graph, for any m⩾0. The proposed procedure is mainly useful when the size of the graph is relatively small, because the search time required is exponential. This exponential search, however, is not always necessary. We prove several necessary conditions that help us, in several cases, to identify some optimal m-fault-tolerant extensions without performing any search 相似文献
5.
Jack J. Domet III T.M. Rajkumar Domet III David Yen 《Information Systems Management》1994,11(4):39-45
The realization of digital multimedia's full business potential requires networking. This article discusses the value-added benefits to the corporation of networked multimedia as well as the choice of architectures and technologies needed to deliver multimedia networking solutions. 相似文献
6.
Nicholas Biery Marc De Graef Jack Beuth Rafel Raban Andrew Elliott Tresa M. Pollock Curt Austin 《Metallurgical and Materials Transactions A》2002,33(10):3127-3136
Tensile experiments have been performed on specimens of four different investment-cast TiAl-based alloys with variations in
casting conditions. The average ductilities obtained in these experiments vary between approximately 0.8 to 2.0 pct plastic
strain to failure in tension. By using the three-parameter form of the Weibull relation, with the 0.2 pct offset yield strength
as the minimum failure strength, the resulting variability in the data can be quantified and is found to be similar for those
alloys with similar microstructural scale (grain size). Large variations in lamellar volume fraction, segregation, and phase
distribution have a minor influence on property variability, compared to changes in the scale of the grain structure caused
by either variations in cooling rate during casting or the addition of grain refiners. 相似文献
7.
8.
Geoffrey M. Eggert Paul R. Dawson Kapil K. Mathur 《International journal for numerical methods in engineering》1991,31(6):1031-1054
A forming model based on a viscoplastic flow formulation is derived which includes the effects of small elastic strains. A significant feature of the formulation is its reliance on the dominant inelastic material characteristics in the formation of the stiffness matrix for large strain problems. The resultant non-linear system of equations is solved by an adaptive descent method which combines the rapid convergence of Newton's method near the solution with the robustness of a method of successive approximations. The use of the adaptive descent method effectively extends the viscoplastic flow formulations into the nearly rate-insensitive range of behaviours exhibited, for example, by metals at low temperature, where slow convergence of the non-linear solution algorithm has traditionally hampered their use. 相似文献
9.
10.
On the learning control of a robot manipulator 总被引:1,自引:0,他引:1
D. M. Dawson Z. Qu J. F. Dorsey F. L. Lewis 《Journal of Intelligent and Robotic Systems》1991,4(1):43-53
This paper derives a learning control law to achieve trajectory following for a robot manipulator. The controller consists of two parts, a computed torque servo for the rigid body terms that can be modelled and a learning law for the unmodelled dynamics. An advantage of this method is that bounds can be assigned to the position and velocity tracking errors. 相似文献