全文获取类型
收费全文 | 1765篇 |
免费 | 81篇 |
国内免费 | 80篇 |
专业分类
电工技术 | 25篇 |
综合类 | 53篇 |
化学工业 | 91篇 |
金属工艺 | 29篇 |
机械仪表 | 48篇 |
建筑科学 | 74篇 |
矿业工程 | 22篇 |
能源动力 | 39篇 |
轻工业 | 118篇 |
水利工程 | 15篇 |
石油天然气 | 38篇 |
武器工业 | 11篇 |
无线电 | 153篇 |
一般工业技术 | 134篇 |
冶金工业 | 11篇 |
原子能技术 | 39篇 |
自动化技术 | 1026篇 |
出版年
2024年 | 9篇 |
2023年 | 13篇 |
2022年 | 19篇 |
2021年 | 31篇 |
2020年 | 30篇 |
2019年 | 28篇 |
2018年 | 28篇 |
2017年 | 43篇 |
2016年 | 53篇 |
2015年 | 48篇 |
2014年 | 88篇 |
2013年 | 92篇 |
2012年 | 89篇 |
2011年 | 155篇 |
2010年 | 114篇 |
2009年 | 110篇 |
2008年 | 115篇 |
2007年 | 129篇 |
2006年 | 125篇 |
2005年 | 108篇 |
2004年 | 109篇 |
2003年 | 100篇 |
2002年 | 42篇 |
2001年 | 32篇 |
2000年 | 25篇 |
1999年 | 32篇 |
1998年 | 26篇 |
1997年 | 16篇 |
1996年 | 10篇 |
1995年 | 16篇 |
1994年 | 10篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 9篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有1926条查询结果,搜索用时 9 毫秒
21.
The popularity of distance education has grown rapidly over the last decade in Taiwan’s higher education, yet many fundamental teaching–learning issues are still in debate. While teacher–student interaction is a key success factor in distance education, little work has been done on the teachers. The intent of this research was to clarify teacher’s perceptions on key distance education issues and to develop a discernible typology of different groups of teachers based on their perceptions. Because there may be a gulf between teachers and the technology used in distance education, the target of this study was teachers in information related departments in Taiwan’s colleges, who were more familiar with current technology. Factor analysis and cluster analysis were used to derive the typology. Five higher-level issue constructs emerged from the factor analysis: learning effect, customization, administrative challenges, geographic and resource integration, and instructional design challenges. Four groups of teachers, namely the skeptics, the optimists, the mild-promising group, and the outlier, were identified using cluster analysis of teachers’ perceptions on these five higher-level issue constructs. The profiles of the four groups of teachers were summarized and implications were discussed, which should provide useful insights to the policy makers of higher education on distance education decisions. 相似文献
22.
P. Morillo A. Bierbaum P. Hartling M. Fernández C. Cruz-Neira 《Journal of Parallel and Distributed Computing》2008
Cluster computing has become an essential issue for designing immersive visualization systems. This paradigm employs scalable clusters of commodity computers with much lower costs than would be possible with the high-end, shared memory computers that have been traditionally used for virtual reality purposes. This change in the design of virtual reality systems has caused some development environments oriented toward shared memory computing to require modifications to their internal architectures in order to support cluster computing. This is the case of VR Juggler, which is considered one of the most important virtual reality application development frameworks based on open source code. 相似文献
23.
Multi-core CPUs,Clusters, and Grid Computing: A Tutorial 总被引:1,自引:0,他引:1
The nature of computing is changing and it poses both challenges and opportunities for economists. Instead of increasing clock
speed, future microprocessors will have “multi-cores” with separate execution units. “Threads” or other multi-processing techniques
that are rarely used today are required to take full advantage of them. Beyond one machine, it has become easy to harness
multiple computers to work in clusters. Besides dedicated clusters, they can be made up of unused lab computers or even your
colleagues’ machines. Finally, grids of computers spanning the Internet are now becoming a reality. 相似文献
24.
含影响力因子的硬聚类算法(HCMef)在对多于两类规模不均的样本进行聚类时,影响力因子指数对聚类结果影响很大,取值不当会引起类消失.影响力因子指数在0附近穷举,并利用影响力因子指数较大时类规模会在较少训练次数内消失的现象,降低计算量.提出了含影响力因子的自适应C均值聚类策略(AHCMef),并介绍了两阶段聚类方法,进一步提高聚类成功率和执行效率.结果显示,最佳影响力因子指数出现在成功聚类时的较大值附近,聚类效果从该点起随影响力因子指数的减小而降低.对HCMef算法应用于多类规模不均样本情况时,影响力因子指数的选取具有指导意义. 相似文献
25.
基于MPI的FDTD并行算法及其优化策略 总被引:1,自引:1,他引:0
由高性能PC机通过网络互联构成的集群(COW)并行计算系统上应用基于消息传递(Message Passing)的方式实现FDTD的并行算法,获得了足够的加速比,有效地解决了传统的FDTD方法计算电大尺寸目标电磁散射问题时的不足.通过区域分割,各个子区域在边界处与其相邻的子区域进行场值的数据传递,从而实现了FDTD算法的并行化.利用并行FDTD方法研究了电磁波的介质层的散射,结果表明并行算法和串行计算结果的一致性,并有效提高计算效率.最后还给出了对算法进行通信隐藏的优化方法,进一步提高了并行计算的效率. 相似文献
26.
Isaac J. Sledge Timothy C. Havens Jacalyn M. Huband James C. Bezdek James M. Keller 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2009,13(12):1125-1142
As humans, we have innate faculties that allow us to efficiently segment groups of objects. Computers, to some degree, can
be programmed with similar categorical capabilities, which stem from exploratory data analysis. Out of the various subsets
of data reasoning, clustering provides insight into the structure and relationships of input samples situated in a number
of distributions. To determine these relationships, many clustering methods rely on one or more human inputs; the most important
being the number of distributions, c, to seek. This work investigates a technique for estimating the number of clusters from a general type of data called relational
data. Several numerical examples are presented to illustrate the effectiveness of the proposed method. 相似文献
27.
介绍一种使用WinHex软件恢复找回u盘文件的方法,利用这种方法,u盘使用者通过一些简单的操作步骤,可尝试对偶尔出现的文件误删、误格式化操作进行恢复,挽回损失。 相似文献
28.
《材料科学技术学报》2019,35(6):1008-1016
The multi-component composition characteristics of high-temperature near-α Ti alloys were investigated in the present work by means of a cluster formula approach. The uniform cluster formula [CN12 cluster](glue atom)3 for the hexagonal close-packed α solid solution was first obtained based on the Friedel oscillation theory, with a total atom number in the formula of Z = 16. Then it was analyzed that the Z values in the cluster composition formulas of typical near-α Ti alloys are within the range of Z = 16.00 ˜ 16.30, being perfectly consistent with the ideal Z = 16. Based on it, a series of new alloys with Z = 16 and with Nb/Ta substitution for Mo in Ti1100 alloy were designed, suction-cast into φ 6 mm rods, and then heat-treated with solid solution and aging. It was found that the alloy with co-addition of Mo, Ta and Nb has a high strength and good ductility at both room and high temperatures. More importantly, the additions of Nb and Ta can contribute to the formation of continuous and compact Al2O3 scales, resulting in an obvious improvement of oxidation resistances at both 923 K and 1073 K. The effects of Mo, Ta and Nb on the oxidation behaviors of the designed alloys at 1073 K were further discussed. 相似文献
29.
In this paper, we develop mathematical models for simultaneous consideration of suitability and optimality in asset allocation. We use a hybrid approach that combines behavior survey, cluster analysis, analytical hierarchy process and fuzzy mathematical programming. 相似文献
30.
并行FFT是解决大数据量FFT运算耗时过久的重要途径,在PC机群上实现并行FFT是一种低成本、高效率的解决方案。本文讨论了PC机群环境下MPI并行FFT实现,并利用建立的平台,对并行算法进行了测试,得出了一些有意义的结论和方法。 相似文献