全文获取类型
收费全文 | 42161篇 |
免费 | 5646篇 |
国内免费 | 2641篇 |
专业分类
电工技术 | 8150篇 |
技术理论 | 3篇 |
综合类 | 3617篇 |
化学工业 | 2649篇 |
金属工艺 | 980篇 |
机械仪表 | 1995篇 |
建筑科学 | 2061篇 |
矿业工程 | 1140篇 |
能源动力 | 3796篇 |
轻工业 | 875篇 |
水利工程 | 1700篇 |
石油天然气 | 3462篇 |
武器工业 | 719篇 |
无线电 | 7003篇 |
一般工业技术 | 5544篇 |
冶金工业 | 766篇 |
原子能技术 | 462篇 |
自动化技术 | 5526篇 |
出版年
2024年 | 272篇 |
2023年 | 834篇 |
2022年 | 1462篇 |
2021年 | 1640篇 |
2020年 | 1624篇 |
2019年 | 1437篇 |
2018年 | 1307篇 |
2017年 | 1620篇 |
2016年 | 1767篇 |
2015年 | 1798篇 |
2014年 | 2698篇 |
2013年 | 2569篇 |
2012年 | 3055篇 |
2011年 | 3394篇 |
2010年 | 2485篇 |
2009年 | 2643篇 |
2008年 | 2298篇 |
2007年 | 2617篇 |
2006年 | 2467篇 |
2005年 | 1977篇 |
2004年 | 1642篇 |
2003年 | 1437篇 |
2002年 | 1160篇 |
2001年 | 999篇 |
2000年 | 941篇 |
1999年 | 761篇 |
1998年 | 621篇 |
1997年 | 512篇 |
1996年 | 462篇 |
1995年 | 390篇 |
1994年 | 319篇 |
1993年 | 291篇 |
1992年 | 227篇 |
1991年 | 169篇 |
1990年 | 151篇 |
1989年 | 105篇 |
1988年 | 67篇 |
1987年 | 40篇 |
1986年 | 24篇 |
1985年 | 32篇 |
1984年 | 34篇 |
1983年 | 17篇 |
1982年 | 17篇 |
1981年 | 8篇 |
1980年 | 14篇 |
1979年 | 12篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1974年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
111.
G. N. Lilis A. Halder S. Telukunta S. Servetto 《International journal for numerical methods in engineering》2007,71(3):277-312
Many problems in geophysics, acoustics, elasticity theory, cancer treatment, food process control and electrodynamics involve study of wave field synthesis (WFS) in some form or another. In the present work, modelling of wave propagation phenomena is studied as a static problem, using finite element method and treating time as an additional spatial dimension. In particular, WFS problems are analysed using discrete methods. It is shown that a fully finite element-based scheme is very natural and effective method for the solution of such problems. Distributed WFS in the context of two-dimensional problems is outlined and incorporation of any geometric or material non-linearities is shown to be straightforward. This has significant implications for problems in geophysics or biological media, where material inhomogeneities are quite prevalent. Numerical results are presented for several problems referring to media with material inhomogeneities and predefined absorption profiles. The method can be extended to three-dimensional problems involving anisotropic media properties in a relatively straightforward manner. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
112.
利用Love波特性计算地基动力响应 总被引:5,自引:2,他引:3
本文利用Love波弥散特性在频域上对地基出平面振动及扭振问题进行了研究。在计算区域内结构将采用有限单元划分,而在边界上则根据Love 面波特性使用传递边界有限单元。本文同时讨论了不同模态波对结构动力响应的贡献。本文方法也适合于静力分析。 相似文献
113.
波浪力计算中的一个新边界元方法 总被引:8,自引:4,他引:4
滕斌 《水动力学研究与进展(A辑)》1994,(2):215-223
本文就波浪与结构物作用问题,提出了一个新的高阶边界元方法。较之Eatock Toylor和Chau的方法,本文在体内附助积分方程中应用了满足刚性水面条件和弱刚性底面条件的简单格林函数。计算速度相应地有所提高;漂浮结构的积分方程更为简洁;计算结果与Eatock Taylor和Chau的方法具有几乎相同的精度和收敛速度。 相似文献
114.
115.
New small‐scale dispersed generation systems, such as fuel cells and micro gas turbines, have made remarkable advances lately and they will be applied practically in the near future. Although a large number of researches on the introduction of small‐scale dispersed generation systems have been carried out, only a small number of small‐scale dispersed generation systems are considered in these researches. Therefore, little is known about problems to be solved when a large number of small‐scale dispersed generation systems are introduced into electric power systems. This paper deals with a super‐distributed energy system that consists of a great number of dispersed generation systems such as fuel cells, micro gas turbines, and so on. The behavior of a customer with a dispersed generation system is simulated as the Ising model in statistical mechanics. The necessity of a distribution network in super‐distributed energy systems is discussed based on the Ising model. The feasibility of decentralized autonomous control using vicinity information is also investigated on the basis of stability analysis of the Hopfield neural network model. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(1): 43–55, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10368 相似文献
116.
Transaction Oriented Prolog-Online Environment is a multi-user, mainframe implementation of the logic programming language Prolog, specially designed and developed for the data processing environment. This article describes the background, functionality, implementation and use of TOP-ONE, stressing that applications of knowledge-based systems technology to data processing environments will achieve full success only when existing systems and existing conventional data are incorporated within the applications. 相似文献
117.
用于疏通油水井的脉冲放电技术 总被引:1,自引:0,他引:1
评价了各种不同的解堵技术,指出冲击波解堵是一种很有发展前途的技术。介绍了液中脉冲放电产生冲击波的基本原理,并由此研制出了一套井下脉冲放电油水井处理设备样机。通过现场试验,表明用冲击波疏通油井能较好地解除油井污染,提高采收率。 相似文献
118.
119.
M. O. Al-Hunaidi 《Journal of Nondestructive Evaluation》1996,15(2):71-82
The potential of using Spectral analysis of surface waves (SASW) for nondestructive testing of pavement and soil sites has been demonstrated in several publications. The usual SASW field testing and data analysis procedures and the assumption of a single propagation mode yield accurate results when there are no sharp changes in the stiffness of the site with depth. When this is not the case, however, difficulties arise in the interpretation of experimental data due to the participation of more than one mode in the wave field. In an earlier study, the multiple filter/crosscorrelation technique was suggested for analyzing multi-mode SASW signals. This technique, however, may not yield accurate results when propagation modes are closely spaced. A more general method using spectral analysis in the frequency wave-number domain is presented in this paper. Formulas are presented for determining a reasonably small number of surface measurements, and the accuracy of this method in resolving experimental dispersion curves is demonstrated for a pavement site. 相似文献
120.
This paper deals with the issues of development and implementation of a real-time NURBS interpolator for a six-axis robot. Using an open-architecture controller system as a testbed, a real-time NURBS curve interpolator was developed, implemented and tested. Sample runs were conducted with the resulting trajectories measured in real-time during robot motion. The resulting trajectories are analyzed, discussed and compared with those from a commonly used point-to-point approximation technique. The real-time NURBS curve interpolator's feasibility, advantages and related issues are also discussed. 相似文献