全文获取类型
收费全文 | 19430篇 |
免费 | 1033篇 |
国内免费 | 507篇 |
专业分类
电工技术 | 636篇 |
技术理论 | 1篇 |
综合类 | 1689篇 |
化学工业 | 2554篇 |
金属工艺 | 446篇 |
机械仪表 | 738篇 |
建筑科学 | 1842篇 |
矿业工程 | 416篇 |
能源动力 | 364篇 |
轻工业 | 1816篇 |
水利工程 | 268篇 |
石油天然气 | 317篇 |
武器工业 | 71篇 |
无线电 | 849篇 |
一般工业技术 | 2809篇 |
冶金工业 | 954篇 |
原子能技术 | 137篇 |
自动化技术 | 5063篇 |
出版年
2024年 | 63篇 |
2023年 | 201篇 |
2022年 | 287篇 |
2021年 | 385篇 |
2020年 | 433篇 |
2019年 | 441篇 |
2018年 | 408篇 |
2017年 | 527篇 |
2016年 | 591篇 |
2015年 | 603篇 |
2014年 | 1113篇 |
2013年 | 1132篇 |
2012年 | 1296篇 |
2011年 | 1549篇 |
2010年 | 1166篇 |
2009年 | 1193篇 |
2008年 | 1013篇 |
2007年 | 1220篇 |
2006年 | 1062篇 |
2005年 | 873篇 |
2004年 | 765篇 |
2003年 | 689篇 |
2002年 | 576篇 |
2001年 | 442篇 |
2000年 | 373篇 |
1999年 | 336篇 |
1998年 | 301篇 |
1997年 | 241篇 |
1996年 | 191篇 |
1995年 | 207篇 |
1994年 | 138篇 |
1993年 | 122篇 |
1992年 | 101篇 |
1991年 | 76篇 |
1990年 | 70篇 |
1989年 | 78篇 |
1988年 | 79篇 |
1987年 | 50篇 |
1986年 | 46篇 |
1985年 | 62篇 |
1984年 | 76篇 |
1983年 | 93篇 |
1982年 | 94篇 |
1981年 | 33篇 |
1980年 | 33篇 |
1979年 | 28篇 |
1978年 | 23篇 |
1977年 | 17篇 |
1976年 | 7篇 |
1955年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
Reducing the complexity of distance measurement methods for circular turbo codes that use structured interleavers 下载免费PDF全文
Youssouf Ould‐Cheikh‐Mouhamedou 《International Journal of Communication Systems》2015,28(9):1572-1579
The knowledge of turbo code's minimum Hamming distance (dmin) and its corresponding codeword multiplicity (Amin) is of a great importance because the error correction capability of a code is strongly tied to the values of dmin and Amin. Unfortunately, the computational complexity associated with the search for dmin and Amin can be very high, especially for a turbo code that has high dmin value. This paper introduces some useful properties of turbo codes that use structured interleavers together with circular encoding. These properties allow for a significant reduction of search space and thus reduce significantly the computational complexity associated with the determination of dmin and Amin values. © 2014 The Authors. International Journal of Communication Systems published by John Wiley & Sons, Ltd. 相似文献
3.
Seong‐Hee Kim 《Quality and Reliability Engineering International》2015,31(6):923-934
We present a distribution‐free tabular cumulative sum chart for monitoring the variability of an autocorrelated process. A quantity known as the asymptotic variance parameter is employed as a measure of the variability, and a distribution‐free tabular cumulative sum chart is applied to variance estimates calculated from batches of nonoverlapping samples. The proposed chart is applicable to a stationary process with a general marginal distribution and a general autocorrelation structure. It also determines control limits analytically without trial‐and‐error simulations. The performance of the proposed chart is tested on stationary processes with both normal and nonnormal marginals with various autocorrelation structures. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
4.
Numerical dissipation acts as artificial viscosity to make smoke viscous. Reducing numerical dissipation is able to recover visual details smeared out by the numerical dissipation. Great efforts have been devoted to suppress the numerical dissipation in smoke simulation in the past few years. In this paper we investigate methods of combating the numerical dissipation. We describe visual consequences of the numerical dissipation and explore sources that introduce the numerical dissipation into course of smoke simulation. Methods are investigated from various aspects including grid variation, high-order advection, sub-grid compensation, invariant conservation, and particle-based improvement, followed by discussion and comparison in terms of visual quality, computational overhead, ease of implementation, adaptivity, and scalability, which leads to their different applicability to various application scenarios. 相似文献
5.
The focus of this paper lies in the practical aspects of voice over IP communication. VoIP configurations in the H.323 standard will be presented briefly. Following that, the fundamental protocol procedure of H.323 communication will be briefly explained. A further part of the paper will address the subject QoS (quality of service), and present the common measurement methods used in QoS. Results gained from experiments conducted in a VoIP environment will then follow. The investigations concentrate primarily on the load behavior of voice packets in relation to important parameters of this service. The results obtained are presented and evaluated in diagrams. The paper concludes with a summary. 相似文献
6.
Matthew R. James 《国际强度与非线性控制杂志
》1994,4(6):791-806
》1994,4(6):791-806
In this paper we present a numerical method for estimating the current state of a nonlinear control system. We use finite differences to discretize a modified version of the finite-time observer equations in James. The discretized equations are simple and easily programmed. The convergence and accuracy of the scheme is proved, and the scheme enjoys a number of important properties: availability of rate of convergence estimates, good robustness characteristics, and the ability to handle certain types of discontinuities in the observations. The major disadvantage is that the number of grid points required increases exponentially with the number of state dimensions. 相似文献
7.
Takeshi Nakajo 《Quality and Reliability Engineering International》1993,9(2):111-119
Work system improvements are implemented in various manufacturing processes to prevent problems caused by human errors. However, they are almost always applied to problems which have already occurred. This paper examines a method of identifying latent human errors existing within the work systems beforehand. A procedure for applying failure mode and effect analysis to this identification problem was defined based on over 1000 empirical errors: a work system decomposition criterion and fundamental error modes for listing latent human errors, and then applied to three practical manufacturing processes in order to evaluate its effectiveness. 相似文献
8.
S. ReppA. Sadiki C. SchneiderA. Hinz T. LandenfeldJ. Janicka 《International Journal of Heat and Mass Transfer》2002,45(6):1271-1285
This work aims to compare numerical results obtained by using the Monte Carlo composition-PDF method and a presumed-β-PDF in order to reveal their effects on the prediction of flow and scalar fields in swirling confined methane diffusion flame. Using the intrinsic low dimensional manifolds method for modelling the chemistry and a second moment closure for the turbulence, it is shown that both PDF-methods provide a similar accuracy level of the prediction of mean quantities. While the presumed-β-PDF performs using reasonable computational efforts, the Monte Carlo-PDF allows to capture well the turbulence-chemistry interaction and strong finite-chemistry effects such as local extinction. 相似文献
9.
10.
Lawrence K. Forbes Graeme C. Hocking Simon Wotherspoon 《Journal of Engineering Mathematics》2004,48(1):69-91
Rainwater can collect in a lens-shaped region within the rock of a tropical island, and may be separated from the underlying salt water by a sharp interface. This paper presents a nonlinear theory for determining the shape of this interface. The island is assumed to be saturated with rain, and provision is made for the outflow of rain-water through the sides of the island. The effect of a bore well on the shape of the interface is investigated, and the problem is solved using a spectral method. An integral-equation method is also presented for the case when the island has infinite width. 相似文献