全文获取类型
收费全文 | 49241篇 |
免费 | 7443篇 |
国内免费 | 5103篇 |
专业分类
电工技术 | 4843篇 |
技术理论 | 1篇 |
综合类 | 6236篇 |
化学工业 | 3753篇 |
金属工艺 | 2855篇 |
机械仪表 | 4744篇 |
建筑科学 | 5428篇 |
矿业工程 | 1812篇 |
能源动力 | 1376篇 |
轻工业 | 3575篇 |
水利工程 | 1720篇 |
石油天然气 | 1432篇 |
武器工业 | 1000篇 |
无线电 | 4014篇 |
一般工业技术 | 5358篇 |
冶金工业 | 1413篇 |
原子能技术 | 227篇 |
自动化技术 | 12000篇 |
出版年
2024年 | 313篇 |
2023年 | 892篇 |
2022年 | 1580篇 |
2021年 | 1711篇 |
2020年 | 1870篇 |
2019年 | 1563篇 |
2018年 | 1568篇 |
2017年 | 1899篇 |
2016年 | 2201篇 |
2015年 | 2267篇 |
2014年 | 3077篇 |
2013年 | 3161篇 |
2012年 | 4029篇 |
2011年 | 3987篇 |
2010年 | 3194篇 |
2009年 | 3157篇 |
2008年 | 3084篇 |
2007年 | 3656篇 |
2006年 | 3136篇 |
2005年 | 2607篇 |
2004年 | 2101篇 |
2003年 | 1713篇 |
2002年 | 1415篇 |
2001年 | 1284篇 |
2000年 | 1173篇 |
1999年 | 889篇 |
1998年 | 755篇 |
1997年 | 655篇 |
1996年 | 538篇 |
1995年 | 478篇 |
1994年 | 389篇 |
1993年 | 304篇 |
1992年 | 246篇 |
1991年 | 182篇 |
1990年 | 165篇 |
1989年 | 154篇 |
1988年 | 96篇 |
1987年 | 50篇 |
1986年 | 34篇 |
1985年 | 34篇 |
1984年 | 41篇 |
1983年 | 30篇 |
1982年 | 23篇 |
1981年 | 11篇 |
1980年 | 25篇 |
1979年 | 18篇 |
1977年 | 4篇 |
1959年 | 4篇 |
1955年 | 4篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
993.
994.
As an important technology for predictive maintenance, failure prognosis has attracted more and more attentions in recent
years. Real-time reliability prediction is one effective solution to failure prognosis. Considering a dynamic system that
is composed of normal, deteriorating and unreliable components, this paper proposes an integrated approach to perform real-time
reliability prediction for such a class of systems. For a deteriorating component, the degradation is modeled by a time-varying
fault process which is a linear or approximately linear function of time. The behavior of an unreliable component is described
by a random variable which has two possible values corresponding to the operating and malfunction conditions of this component.
The whole proposed approach contains three algorithms. A modified interacting multiple model particle filter is adopted to
estimate the dynamic system’s state variables and the unmeasurable time-varying fault. An exponential smoothing algorithm
named the Holt’s method is used to predict the fault process. In the end, the system’s reliability is predicted in real time
by use of the Monte Carlo strategy. The proposed approach can effectively predict the impending failure of a dynamic system,
which is verified by computer simulations based on a three-vessel water tank system. 相似文献
995.
介绍了认知无线电的研究现状,对认知无线电系统中已有的动态频谱分配模型进行了分析并结合各种算法进行了比较。在此基础上总结并提出了频谱共享的一些挑战性问题,探讨了动态频谱分配的一些热点问题并构想了未来的发展方向。 相似文献
996.
该文给出了UML的概念与要点,应用UML对教学考评系统进行了建模。给出了系统的用例模型、整体结构模型、静态模型、动态模型,并分析了模型对教学考评变化的可适应性。 相似文献
997.
流行的Segmenter分词算法是开放的java源代码,它是一个很好的分词工具。但是,在全文检索系统中对分词有特殊的要求,例如歧义包客、专业词典等。所以在这里将Segmenter词典和算法都进行了改选,建立了树状词典,在匹配算法中使用了歧义包容法则、分支处理、动态规划和词库预载入。以适应电子商务案例全文检索系统。 相似文献
998.
This paper investigates the controllability of multi-agent systems based on agreement protocols. First, for a group of single-integrator
agents, the controllability is studied in a unified framework for both networks with leader-following structure and networks
with undirected graph. Some new necessary/sufficient conditions for the controllability of networks of single-integrator agents
are established. Second, we prove that, under the same topology and same prescribed leaders, a network of high-order dynamic
agents is completely controllable if and only if so is a network of single-integrator agents. Third, how the selection of
leaders and the coupling weights of graphs affect the controllability is analyzed. Finally, some numerical simulations are
presented to demonstrate the effectiveness of the theoretical results. 相似文献
999.
A new patch-based texture synthesis method is presented in this paper. By the method, a set of patches that can be matched
with a sampled patch for growing textures effectively, called the matching compatibility between patches, is generated first
for each patch, and the set is further optimized by culling the patches that may cause synthesis conflicts. In this way, similarity
measurement calculation for selecting suitable patches in texture synthesis can be greatly saved, and synthesis conflicts
between neighbouring patches are substantially reduced. Furthermore, retrace computation is integrated in the synthesis process
to improve the texture quality. As a result, the new method can produce high quality textures as texture optimization, the
best method to date for producing good textures, and run in a time complexity linear to the size of the output texture. Experimental
results show that the new method can interactively generate a large texture in 1024 × 1024 pixels, which is very difficult
to achieve by existing methods.
Supported by the National Basic Research Program of China (Grant No. 2009CB320802), the National Natural Science Foundation
of China (Grant Nos. 60773026, 60833007), the National High-Tech Research & Development Program of China (Grant Nos. 2006AA01Z306,
2008AA01Z301), and the Research Grant of University of Macau 相似文献
1000.
杨泉 《数字社区&智能家居》2009,(21)
该文在对图像特征分析及相似检索方法研究分析的基础上,提出了一种基于色调局部累加直方图与纹理特征结合的相似性匹配度量算法。该算法不但缩短了查询时间,而且通过实验证明,该算法有较高的检索率。 相似文献