全文获取类型
收费全文 | 2569篇 |
免费 | 131篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 42篇 |
综合类 | 4篇 |
化学工业 | 636篇 |
金属工艺 | 72篇 |
机械仪表 | 29篇 |
建筑科学 | 120篇 |
矿业工程 | 11篇 |
能源动力 | 35篇 |
轻工业 | 205篇 |
水利工程 | 4篇 |
石油天然气 | 3篇 |
无线电 | 190篇 |
一般工业技术 | 571篇 |
冶金工业 | 250篇 |
原子能技术 | 22篇 |
自动化技术 | 511篇 |
出版年
2023年 | 30篇 |
2022年 | 29篇 |
2021年 | 65篇 |
2020年 | 44篇 |
2019年 | 42篇 |
2018年 | 60篇 |
2017年 | 49篇 |
2016年 | 72篇 |
2015年 | 67篇 |
2014年 | 91篇 |
2013年 | 142篇 |
2012年 | 130篇 |
2011年 | 152篇 |
2010年 | 116篇 |
2009年 | 108篇 |
2008年 | 132篇 |
2007年 | 117篇 |
2006年 | 93篇 |
2005年 | 88篇 |
2004年 | 96篇 |
2003年 | 62篇 |
2002年 | 58篇 |
2001年 | 48篇 |
2000年 | 56篇 |
1999年 | 55篇 |
1998年 | 90篇 |
1997年 | 60篇 |
1996年 | 53篇 |
1995年 | 44篇 |
1994年 | 27篇 |
1993年 | 27篇 |
1992年 | 38篇 |
1991年 | 28篇 |
1990年 | 29篇 |
1989年 | 23篇 |
1988年 | 19篇 |
1987年 | 21篇 |
1986年 | 25篇 |
1985年 | 28篇 |
1984年 | 14篇 |
1983年 | 21篇 |
1982年 | 15篇 |
1980年 | 14篇 |
1979年 | 14篇 |
1978年 | 11篇 |
1977年 | 18篇 |
1976年 | 22篇 |
1974年 | 8篇 |
1973年 | 8篇 |
1969年 | 8篇 |
排序方式: 共有2705条查询结果,搜索用时 98 毫秒
1.
2.
Seidel A.R. Bisogno F.E. Pinheiro H. do Prado R.N. 《Industrial Electronics, IEEE Transactions on》2003,50(6):1267-1274
This paper presents a simple alternative for an electronic ballast operating in self-sustained oscillating mode with dimming capability for fluorescent lamps. A simple modification in one of the gate drivers side circuit allows the lamp to dim without compromising the simplicity, reliability, and low cost which characterize the self-oscillating electronic ballast (SOEB). A qualitative analysis is presented to explain the behavior of the proposed self-oscillating electronic ballast with dimming feature. In addition, the stability and the key equations for the design are derived using the extended Nyquist criterion and describing function method. Experimental results from two 40-W electronic ballasts are presented to demonstrate the performance and to validate the analysis carried out. 相似文献
3.
Hans-Jürgen Odenthal Herbert Pfeifer Ina Lemanowicz Rainer Gorissen 《Metallurgical and Materials Transactions B》2002,33(2):163-172
The present work describes quantitative digital particle image velocimetry measurements of a full-scale water model of a thin
slab mold. Different casting speeds and two submerged entry nozzles with one and two outlet ports have been investigated.
The flow pattern of the single-port nozzle shows a counterclockwise-rotating double vortex that is nearly steady-state but
leads to high stationary surface waves. The flow jets out of the two-port nozzle oscillate and produce a transient flow pattern
with low wave amplitudes. The amplitudes for the one-port nozzle show a linear variation with the volumetric flow rate. The
experimental results lead to a good interpretation of the flow phenomena and are used to validate steady-state numerical simulations
with the commercial program, CFX, on the basis of the Reynolds equations. To describe anisotropic turbulence effects, the
Reynolds stress model (RSM) is used for the flat single-port nozzle and the standard k-ɛ model for the mold flow. The calculated mean velocities and wave amplitudes, predicted from pressure distribution at the
water surface, are generally in the consensus of the experimental data.
An erratum to this article is available at . 相似文献
4.
5.
6.
7.
In recent years, a wide range of generalized barycentric coordinates has been suggested. However, all of them lack control over derivatives. We show how the notion of barycentric coordinates can be extended to specify derivatives at control points. This is also known as Hermite interpolation. We introduce a method to modify existing barycentric coordinates to higher order barycentric coordinates and demonstrate, using higher order mean value coordinates, that our method, although conceptually simple and easy to implement, can be used to give easy and intuitive control at interactive frame rates over local space deformations such as rotations. 相似文献
8.
Until recently, numerical simulations of discontinuities in highly super-Alfvénic plasmas have been severely limited by comparatively crude resolution and accuracy. Significant progress in the numerical simulation of such plasmas was achieved with the recently implemented Central Weighted Essentially Non-Oscillatory (CWENO) scheme. Combining this technique with that of adaptive mesh refinement (AMR), we have developed a third-order numerical scheme, which is able to efficiently capture strong gradients on spatial scales being small compared to the overall scale of the plasma system considered. Here, we first describe important algorithmic aspects of the scheme as well as the physics included in it. Second, we present the results of various performance tests. And, third, we illustrate its application to ‘real world problems’ using the example of the dynamics of a Sedov-type explosion. 相似文献
9.
10.
Here, we describe the development of a reacting flow multi-species/combustion methodology, implemented as an extension to the differential reduced ejector analysis (DREA) computer program [Mathematical and computer modeling, vol. 31, 2000, p. 21; Appl. Math. Model. 25 (2001) 427; Comput. Math. Appl. 43(10–11); NASA Contractor Report, 1998]. Use of the single fluid IVP solver framework that was developed for the original DREA model has been directly coupled into the combustion formulation. With these modifications, the analysis has an elementary single step reaction Fuel+Oxidizer→Product combustion capability. Though approximate in nature, the simplicity and efficiency of the DREA formulation make it suitable for its original niche, namely design and preliminary design environments where more complex and expensive models may be inappropriate. 相似文献