全文获取类型
收费全文 | 12320篇 |
免费 | 125篇 |
国内免费 | 146篇 |
专业分类
电工技术 | 149篇 |
综合类 | 4篇 |
化学工业 | 789篇 |
金属工艺 | 458篇 |
机械仪表 | 93篇 |
建筑科学 | 131篇 |
矿业工程 | 5篇 |
能源动力 | 129篇 |
轻工业 | 253篇 |
水利工程 | 57篇 |
石油天然气 | 18篇 |
无线电 | 476篇 |
一般工业技术 | 420篇 |
冶金工业 | 300篇 |
原子能技术 | 105篇 |
自动化技术 | 9204篇 |
出版年
2024年 | 5篇 |
2023年 | 34篇 |
2022年 | 93篇 |
2021年 | 116篇 |
2020年 | 79篇 |
2019年 | 78篇 |
2018年 | 74篇 |
2017年 | 76篇 |
2016年 | 79篇 |
2015年 | 80篇 |
2014年 | 274篇 |
2013年 | 319篇 |
2012年 | 911篇 |
2011年 | 3208篇 |
2010年 | 1230篇 |
2009年 | 1109篇 |
2008年 | 763篇 |
2007年 | 673篇 |
2006年 | 531篇 |
2005年 | 643篇 |
2004年 | 580篇 |
2003年 | 615篇 |
2002年 | 321篇 |
2001年 | 31篇 |
2000年 | 19篇 |
1999年 | 48篇 |
1998年 | 141篇 |
1997年 | 61篇 |
1996年 | 37篇 |
1995年 | 20篇 |
1994年 | 20篇 |
1993年 | 20篇 |
1992年 | 17篇 |
1991年 | 22篇 |
1990年 | 18篇 |
1989年 | 26篇 |
1988年 | 17篇 |
1987年 | 21篇 |
1986年 | 27篇 |
1985年 | 14篇 |
1984年 | 35篇 |
1983年 | 21篇 |
1982年 | 9篇 |
1981年 | 13篇 |
1980年 | 15篇 |
1979年 | 4篇 |
1976年 | 9篇 |
1975年 | 4篇 |
1974年 | 7篇 |
1972年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Navab SinghAuthor Vitae Moitreyee Mukherjee-RoyAuthor VitaeSohan Singh MehtaAuthor Vitae 《Microelectronics Journal》2003,34(4):237-245
The patterning of contact holes by selecting out-of-focus image plane (defocus) using attenuated phase shift masks (APSM) has been studied. Defocus is found to enhance the image modulation at low partial coherence for contact holes with negative local average of mask function. Semi-dense holes up to 130 nm in 8% APSM have been printed by 0.5 μm defocus at a partial coherence of 0.31 using KrF scanner with highest numerical aperture of 0.68. However, these holes were closed with in-focus imaging. Defocus is also found to be beneficial for patterning the pitches that have extensive side lobes with in-focus imaging. 相似文献
4.
George V. Eleftheriades Gabriel M. Rebeiz 《Journal of Infrared, Millimeter and Terahertz Waves》1993,14(10):1925-1946
In this paper, an efficient implementation of the spectral domain moment technique is presented for computing the self and mutual coupling between slot antennas on a dielectric half-space. It is demonstrated that by the proper selection of the weighting functions in the method of moments, the analytic evaluation or simplification of the transverse moment integrals is enabled. This results into a significant reduction of the required computational labor. The method is then utilized in order to provide design data for the self and mutual admittances between two slot antennas on a dielectric substrate lens in the case of fused quartz (∈ r =3.80), crystal quartz (∈ r =4.53), silicon (∈ r =11.9) and GaAs (∈ r =12.8). The presented technique and associated results are useful when designing twin slot quasi-optical receivers, imaging arrays, phased arrays or power-combining arrays of slot elements at millimeter-wave frequencies. 相似文献
5.
6.
A micromechanics analysis is performed for the determination of the five independent elastic moduli of unidirectional fiber composites. By considering viscoelastic phases and by using the correspondence principle and the inversion of the Laplace transform, the five time-dependent functions which characterize the effective behavior of viscoelastic composites are established. The predicted time-dependent behavior is applied for the analysis of viscoelastic laminated plates. The resulting viscoelastic effects are shown, and comparison between the results obtained within the classical laminated plate theory and the first-order shear deformation theory is discussed. 相似文献
7.
Gabriel Wainer 《Software》2002,32(13):1261-1306
The features of a toolkit for modeling and simulation based on the DEVS formalism are presented. The tool is built as a set of independent software pieces running on different platforms. Not only are the main characteristics of the environment presented, a focus on its use is also considered by inclusion of application examples for a variety of problems. Many models can be defined in an automated fashion, simplifying the construction of new models and easing their verification. The use of this formal approach has allowed the development of safe and cost‐effective simulations, significantly reducing development time. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
8.
9.
A stochastic realization problem of a stationary stochastic process is re-visited, and a new stochastically balanced realization algorithm is derived in a Hilbert space generated by second-order stationary processes. The present algorithm computes a stochastically balanced realization by means of the singular value decomposition of a weighted block Hankel matrix derived by a “block LQ decomposition”. Extension to a stochastic subspace identification method explains how the proposed abstract algorithm is implemented in system identification. 相似文献
10.
Gabriel Nivasch 《Information Processing Letters》2004,90(3):135-140
We present an algorithm for detecting periodicity in sequences produced by repeated application of a given function. Our algorithm uses logarithmic memory with high probability, runs in linear time, and is guaranteed to stop within the second loop through the cycle. We also present a partitioning technique that offers a time/memory tradeoff. Our algorithm is especially well suited for sequences where the cycle length is typically small compared to the length of the acyclic prefix. 相似文献