全文获取类型
收费全文 | 785篇 |
免费 | 28篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 9篇 |
综合类 | 1篇 |
化学工业 | 137篇 |
金属工艺 | 10篇 |
机械仪表 | 26篇 |
建筑科学 | 21篇 |
矿业工程 | 2篇 |
能源动力 | 7篇 |
轻工业 | 64篇 |
石油天然气 | 1篇 |
无线电 | 128篇 |
一般工业技术 | 116篇 |
冶金工业 | 219篇 |
原子能技术 | 3篇 |
自动化技术 | 70篇 |
出版年
2023年 | 5篇 |
2022年 | 10篇 |
2021年 | 13篇 |
2019年 | 10篇 |
2018年 | 5篇 |
2017年 | 8篇 |
2016年 | 11篇 |
2015年 | 12篇 |
2014年 | 17篇 |
2013年 | 30篇 |
2012年 | 18篇 |
2011年 | 22篇 |
2010年 | 25篇 |
2009年 | 15篇 |
2008年 | 33篇 |
2007年 | 25篇 |
2006年 | 30篇 |
2005年 | 21篇 |
2004年 | 23篇 |
2003年 | 22篇 |
2002年 | 12篇 |
2001年 | 24篇 |
2000年 | 26篇 |
1999年 | 17篇 |
1998年 | 54篇 |
1997年 | 36篇 |
1996年 | 30篇 |
1995年 | 14篇 |
1994年 | 22篇 |
1993年 | 18篇 |
1992年 | 8篇 |
1991年 | 12篇 |
1990年 | 15篇 |
1989年 | 13篇 |
1988年 | 12篇 |
1987年 | 16篇 |
1986年 | 4篇 |
1985年 | 15篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1978年 | 6篇 |
1977年 | 9篇 |
1976年 | 23篇 |
1975年 | 3篇 |
1974年 | 6篇 |
1970年 | 4篇 |
1969年 | 6篇 |
1968年 | 4篇 |
排序方式: 共有814条查询结果,搜索用时 10 毫秒
1.
Krenz William Robin Michael Barez Shirin Stark Lawrence 《IEEE transactions on bio-medical engineering》1985,(10):817-825
A model of the pathways controlling the size of the human pupil is presented. Computer simulation of this model demonstrates the role played by each of the elements in the pupil pathways. Simulations of the effects of drugs and a few common abnormalities in the system also help to illustrate the workings of the internal processes. Computer models of this type can be used as teaching aids or as tools for testing of hypotheses regarding the system. 相似文献
2.
The CMOS-storage emitter-access (CSEA) memory cell offers faster access than the MOS cells used in conventional BiCMOS SRAMs but using it in large memory arrays poses several problems. Novel BiCMOS circuit approaches to address the problems of decoding power, electronic noise, level translation, and write disturbance are described. Results on a 64-kb CSEA SRAM using these techniques are reported. The device, fabricated in an 0.8-μm BiCMOS technology, achieves read access and write pulse time of less than 4 ns while dissipating 1.7 W at a case temperature of 70°C 相似文献
3.
Adaptive generation of surfaces in volume data 总被引:1,自引:1,他引:0
A widespread approach to generating polygonal approximations of iso-surfaces or contour surfaces in volume data is the socalled marching-cubes algorithm. This algorithm, however, has the disadvantage that the number of polygonal chains generated is considerable. The splitting-box algorithm presented here reduces the number of polygonal chains by adapting their size to the shape of the surface. The resulting polygonal chains offer a wide spectrum for representing the contour surface. An exact representation is achieved by a new type of generic patches calculated from the polygonal chains. Approximations of different quality may be obtained by combining the algorithm generating the patches with simple triangulations. 相似文献
4.
From the results reported here it is suggested that policy decisions about the potential contribution of decentralized energy supply systems to UK industrial energy requirements should be based on the suitability of individual sectors rather than averaged over all sectors. The suitability of decentralized energy sources is evaluated, based on a themodynamic match between source and demand. This suitability criterion is used to identify the most appropriate sector in manufacturing industries for the adoption of decentralized energy supply, leaving aside economic cost considerations and individual site requirements. 相似文献
5.
The Hutchinson metric is a natural measure of the discrepancy between two images for use in fractal image processing. A neural network is described which can quickly calculate this metric. By combining this with the architecture previously described by the author for implementing the Markov operator of an iterated function system (IFS) on a neural network, a fast method is obtained for determining the distance between a target image and the invariant measure of a trial IFS. This has obvious applications to Barnsley's fractal image compression scheme 相似文献
6.
This paper considers the application of trellis coding techniques to direct-sequence spread-spectrum multiple-access (DS/SSMA) communication. The unique feature of the trellis codes considered is that they are constructed over the set of possible signature sequences rather than over some standard 2-D signal constellation. The resulting codes have a small number of signals per dimension. We present several examples of these trellis codes, and suggest possible methods of implementation. We also present a detailed error analysis for this system, which employs techniques developed by Lehnert and Pursley (1987, 1989)) to accurately model the multiple access interference. We generate numerical results for several examples and conclude that the proposed trellis coded systems yield significant performance improvements over binary antipodal DS/SSMA systems. In addition, the new trellis codes perform better than standard error control techniques with the same complexity and code rate. Analytic results are verified with simulations 相似文献
7.
The performance of a countermeasure technique in the presence of the optimal follower multitone jammer is evaluated for frequency-hopped spread spectrum (FHSS) communications. It is shown that, with a certain probability, the optimal jammer will have dual tones in a frequency channel 相似文献
8.
Es werden die experimentellen und numerischen Ergebnisse dargelegt, um die gesamte Spannungs-Dehnungs-Kurve des Zugversuches mit sechs Kennwerten zu beschreiben. Dies sind: Elastizitätsmodul, Streckgrenze, Fließdehnung, Zugfestigkeit, Gleichmaßdehnung und Verfestigungsmodul. Dadurch werden auch im überelastischen Bereich numerische Beziehungen möglich zwischen: Verformungen und Spannungen, Dehngrenzen, Tangenten-Modulen und Arbeitsvermögen. Die Beziehungen erweitern die Ermittlung von Last- und Eigenspannungen, und die Berechnungen beim plastischen Umformen, beim Traglastverfahren und beim Messen von Kerbspannungen. 相似文献
9.
We consider the problem of reconstructing tomographic imagery from fan-beam projections using the direct Fourier method (DFM). Previous DFM reconstructions from parallel-beam projections produced images of quality comparable to that of filtered convolution back-projection. Moreover, the number of operations using DFM in the parallel-beam case is proportional to N2 log N versus N3 for back projection [3]. The fan-beam case is more complicated because additional interpolation of the nonuniformly spaced rebinned data is required. We derive bounds on the detector spacing in fan-beam CT that enable direct Fourier reconstruction and describe the full algorithm necessary for processing the fan-beam data. The feasibility of the method is demonstrated with an example. A key result of this paper is that high-quality imagery can be reconstructed from fan-beam data using the DFM in 0 (N2 log N) operations. 相似文献
10.
Although wood–plastic composites have become more accepted and used in recent years and are promoted as low‐maintenance, high‐durability building products, they do experience a color change and a loss in mechanical properties with accelerated weathering. In this study, we attempted to characterize the modulus‐of‐elasticity (MOE) loss of photostabilized high‐density polyethylene (HDPE) and composites of wood flour and high‐density polyethylene (WF/HDPE) with accelerated weathering. We then examined how weathering changed the surface chemistry of the composites and looked at whether or not the surface changes were related to the MOE loss. By examining surface chemistry changes, we hoped to begin to understand what caused the weathering changes. The materials were left unstabilized or were stabilized with either an ultraviolet absorber or pigment. After 1000 and 2000 h of accelerated weathering, the samples were tested for MOE loss. Fourier transform infrared (FTIR) spectroscopy was employed to monitor carbonyl and vinyl group formation at the surface. Changes in the HDPE crystallinity were also determined with FTIR techniques. It was determined that structural changes in the samples (carbonyl group formation, terminal vinyl group formation, and crystallinity changes) could not be reliably used to predict changes in MOE with a simple linear relationship. This indicated that the effects of crosslinking, chain scission, and crystallinity changes due to ultraviolet exposure and interfacial degradation due to moisture exposure were interrelated factors for the weathering of HDPE and WF/HDPE composites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2263–2273, 2004 相似文献