全文获取类型
收费全文 | 7477篇 |
免费 | 817篇 |
国内免费 | 631篇 |
专业分类
电工技术 | 397篇 |
技术理论 | 1篇 |
综合类 | 976篇 |
化学工业 | 433篇 |
金属工艺 | 175篇 |
机械仪表 | 334篇 |
建筑科学 | 264篇 |
矿业工程 | 154篇 |
能源动力 | 164篇 |
轻工业 | 146篇 |
水利工程 | 516篇 |
石油天然气 | 394篇 |
武器工业 | 68篇 |
无线电 | 937篇 |
一般工业技术 | 874篇 |
冶金工业 | 215篇 |
原子能技术 | 152篇 |
自动化技术 | 2725篇 |
出版年
2024年 | 22篇 |
2023年 | 74篇 |
2022年 | 136篇 |
2021年 | 176篇 |
2020年 | 206篇 |
2019年 | 182篇 |
2018年 | 187篇 |
2017年 | 218篇 |
2016年 | 289篇 |
2015年 | 285篇 |
2014年 | 369篇 |
2013年 | 548篇 |
2012年 | 534篇 |
2011年 | 559篇 |
2010年 | 381篇 |
2009年 | 442篇 |
2008年 | 470篇 |
2007年 | 498篇 |
2006年 | 464篇 |
2005年 | 398篇 |
2004年 | 335篇 |
2003年 | 346篇 |
2002年 | 290篇 |
2001年 | 216篇 |
2000年 | 204篇 |
1999年 | 150篇 |
1998年 | 137篇 |
1997年 | 129篇 |
1996年 | 120篇 |
1995年 | 64篇 |
1994年 | 101篇 |
1993年 | 71篇 |
1992年 | 65篇 |
1991年 | 31篇 |
1990年 | 36篇 |
1989年 | 23篇 |
1988年 | 22篇 |
1987年 | 17篇 |
1986年 | 17篇 |
1985年 | 23篇 |
1984年 | 9篇 |
1983年 | 17篇 |
1982年 | 12篇 |
1981年 | 7篇 |
1980年 | 12篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1975年 | 4篇 |
1962年 | 2篇 |
排序方式: 共有8925条查询结果,搜索用时 0 毫秒
61.
62.
The shapes of if-part fuzzy sets affect the approximating capability of fuzzy systems. In this paper, the fuzzy systems with the kernel-shaped if-part fuzzy sets are built directly from the training data. It is proved that these fuzzy systems are universal approximators and their uniform approximation rates can be estimated in the single-input-single-output (SISO) case. On the basis of these rates, the relationships between the approximating capability and the shapes of if-part fuzzy sets are developed for the fuzzy systems. Furthermore, the sinc functions that serve as input membership functions are proved to have the almost best approximation property in a particular class of membership functions. The theoretical results are confirmed from the simulation data. In addition, the estimations of the uniform approximation rates are extended to the multi-input-single-output (MISO) case. 相似文献
63.
A new likelihood based AR approximation is given for ARMA models. The usual algorithms for the computation of the likelihood of an ARMA model require O(n) flops per function evaluation. Using our new approximation, an algorithm is developed which requires only O(1) flops in repeated likelihood evaluations. In most cases, the new algorithm gives results identical to or very close to the exact maximum likelihood estimate (MLE). This algorithm is easily implemented in high level quantitative programming environments (QPEs) such as Mathematica, MatLab and R. In order to obtain reasonable speed, previous ARMA maximum likelihood algorithms are usually implemented in C or some other machine efficient language. With our algorithm it is easy to do maximum likelihood estimation for long time series directly in the QPE of your choice. The new algorithm is extended to obtain the MLE for the mean parameter. Simulation experiments which illustrate the effectiveness of the new algorithm are discussed. Mathematica and R packages which implement the algorithm discussed in this paper are available [McLeod, A.I., Zhang, Y., 2007. Online supplements to “Faster ARMA Maximum Likelihood Estimation”, 〈http://www.stats.uwo.ca/faculty/aim/2007/faster/〉]. Based on these package implementations, it is expected that the interested researcher would be able to implement this algorithm in other QPEs. 相似文献
64.
Segment-based adaptive hyper-Erlang model for long-tailed network traffic approximation 总被引:1,自引:1,他引:0
Modeling the long-tailedness property of network traffic with phase-type distributions is a powerful means to facilitate the consequent performance evaluation and queuing based analysis. This paper
improves the recently proposed Fixed Hyper-Erlang model (FHE) by introducing an adaptive framework (Adaptive Hyper-Erlang
model, AHE) to determine the crucially performance-sensitive model parameters. The adaptive model fits long-tailed traffic
data set directly with a mixed Erlang distribution in a new divide-and-conquer manner. Compared with the well-known hyperexponential based models and the Fixed Hyper-Erlang model, the Adaptive Hyper-Erlang
model is more flexible and practicable in addition to its accuracy in fitting the tail behavior.
相似文献
Junfeng WangEmail: |
65.
John Stachurski 《Computational Economics》2008,31(2):141-160
This paper studies fitted value iteration for continuous state numerical dynamic programming using nonexpansive function approximators.
A number of approximation schemes are discussed. The main contribution is to provide error bounds for approximate optimal
policies generated by the value iteration algorithm.
相似文献
66.
CAO FeiLong ZHANG YongQuan & XU ZongBen College of Science China Jiliang University Hangzhou China Institute of Information System Sciences Xi’an Jiaotong University Xi’an 《中国科学F辑(英文版)》2009,52(8):1321-1327
Let SFd and Πψ,n,d = { nj=1bjψ(ωj·x+θj) :bj,θj∈R,ωj∈Rd} be the set of periodic and Lebesgue’s square-integrable functions and the set of feedforward neural network (FNN) functions, respectively. Denote by dist (SF d, Πψ,n,d) the deviation of the set SF d from the set Πψ,n,d. A main purpose of this paper is to estimate the deviation. In particular, based on the Fourier transforms and the theory of approximation, a lower estimation for dist (SFd, Πψ,n,d) is proved. That is, dist(SF d, Πψ,n,d) (nlogC2n)1/2 . T... 相似文献
67.
Sampled-data based average consensus with measurement noises: convergence analysis and uncertainty principle 总被引:1,自引:0,他引:1
In this paper, sampled-data based average-consensus control is considered for networks consisting of continuous-time first-order
integrator agents in a noisy distributed communication environment. The impact of the sampling size and the number of network
nodes on the system performances is analyzed. The control input of each agent can only use information measured at the sampling
instants from its neighborhood rather than the complete continuous process, and the measurements of its neighbors’ states
are corrupted by random noises. By probability limit theory and the property of graph Laplacian matrix, it is shown that for
a connected network, the static mean square error between the individual state and the average of the initial states of all
agents can be made arbitrarily small, provided the sampling size is sufficiently small. Furthermore, by properly choosing
the consensus gains, almost sure consensus can be achieved. It is worth pointing out that an uncertainty principle of Gaussian
networks is obtained, which implies that in the case of white Gaussian noises, no matter what the sampling size is, the product
of the steady-state and transient performance indices is always equal to or larger than a constant depending on the noise
intensity, network topology and the number of network nodes. 相似文献
68.
基于相似关系的决策系统的知识获取算法 总被引:1,自引:1,他引:0
陈世联 《计算机工程与科学》2009,31(5)
本文基于一种相似关系下的粗糙集模型,给出了一些基本性质,讨论了该相似关系下的决策系统的知识获取算法。该算法可以避免因数据离散化的处理而产生的信息系统相似度的误差。 相似文献
69.
一种新的覆盖粗糙集及其模糊性度量 总被引:2,自引:0,他引:2
在覆盖近似空间中定义了一类新的模糊集,给出了该类模糊集的模糊性度量,讨论模糊集及其模糊度量的性质,最后通过实例给出直观解释. 相似文献
70.
基于改进的Capon滤波器组谱估计新方法 总被引:1,自引:0,他引:1
为了解决Capon滤波器组谱估计方法在α稳定分布噪声下性能出现退化的问题,提出了一种改进的Capon滤波器组谱估计方法,利用分数低阶协方差(FLOC)对传统的Capon滤波器组进行重构.由于分数低阶协方差的作用范围是0<α≤2整个分数低阶空间,因此在α稳定分布噪声下其谱估计性能比基于二阶统计量方法的谱估计性能更好.计算机仿真结果显示了这种方法的优越性能,并且在高斯噪声环境下,其性能与二阶统计量下的方法类似. 相似文献