全文获取类型
收费全文 | 4709篇 |
免费 | 66篇 |
国内免费 | 23篇 |
专业分类
电工技术 | 29篇 |
综合类 | 6篇 |
化学工业 | 219篇 |
金属工艺 | 18篇 |
机械仪表 | 31篇 |
建筑科学 | 109篇 |
矿业工程 | 1篇 |
能源动力 | 103篇 |
轻工业 | 45篇 |
水利工程 | 6篇 |
石油天然气 | 1篇 |
武器工业 | 1篇 |
无线电 | 667篇 |
一般工业技术 | 312篇 |
冶金工业 | 2743篇 |
原子能技术 | 40篇 |
自动化技术 | 467篇 |
出版年
2023年 | 6篇 |
2022年 | 11篇 |
2021年 | 27篇 |
2020年 | 25篇 |
2019年 | 23篇 |
2018年 | 21篇 |
2017年 | 24篇 |
2016年 | 39篇 |
2015年 | 30篇 |
2014年 | 59篇 |
2013年 | 120篇 |
2012年 | 78篇 |
2011年 | 116篇 |
2010年 | 68篇 |
2009年 | 99篇 |
2008年 | 111篇 |
2007年 | 128篇 |
2006年 | 109篇 |
2005年 | 84篇 |
2004年 | 98篇 |
2003年 | 87篇 |
2002年 | 78篇 |
2001年 | 60篇 |
2000年 | 60篇 |
1999年 | 142篇 |
1998年 | 790篇 |
1997年 | 517篇 |
1996年 | 372篇 |
1995年 | 181篇 |
1994年 | 152篇 |
1993年 | 210篇 |
1992年 | 45篇 |
1991年 | 74篇 |
1990年 | 65篇 |
1989年 | 76篇 |
1988年 | 58篇 |
1987年 | 43篇 |
1986年 | 47篇 |
1985年 | 48篇 |
1984年 | 16篇 |
1983年 | 15篇 |
1982年 | 24篇 |
1981年 | 33篇 |
1980年 | 30篇 |
1979年 | 12篇 |
1978年 | 15篇 |
1977年 | 75篇 |
1976年 | 168篇 |
1974年 | 9篇 |
1973年 | 6篇 |
排序方式: 共有4798条查询结果,搜索用时 437 毫秒
141.
Data races hamper parallel programming and threaten the reliability of future software. This paper proposes the data race
prevention scheme View-Oriented Data race Prevention (VODAP), which can prevent data races in the View-Oriented Parallel Programming
(VOPP) model. VOPP is a novel shared-memory data-centric parallel programming model, which uses views to bundle mutual exclusion
with data access. We have implemented the data race prevention scheme with a memory protection mechanism. Experimental results
show that the extra overhead of memory protection is trivial in our applications. The performance is evaluated and compared
with modern programming models such as OpenMP and Cilk. 相似文献
142.
Yiu-Wing Leung 《Computer Networks》2010,54(1):150-164
143.
Next generation heterogeneous wireless networks are expected to interwork with Internet Protocol (IP)-based infrastructures. Conventional network services operate like silos in that a specific set of services are offered over a specific type of access network. It is desirable for users to be able to roam between fixed and mobile networks that employ different access technologies. Therefore, mobility management with quality of service (QoS) support is of particular importance and one of the driving forces of convergence. Since service providers often provide more than one service to their subscribers, it is important to facilitate convergence of network charging architecture through a common charging framework. One of the main issues of IP-based convergence is security and privacy. This requires coordination of different security policies in diverse networks that have different security levels and capabilities. The business case for migration to an IP-based platform motivates operators to deliver more powerful services for customers as well as a better user experience. This paper provides an overview of converged mobile Internet architectures and their implications on QoS, charging/billing and security, as well as emerging business models for telecommunication services. 相似文献
144.
Many researches have been devoted to select the kernel parameters, including the centers, kernel width and weights, for fault-free
radial basis function (RBF) neural networks. However, most are concerned with the centers and weights identification, and
fewer focus on the kernel width selection. Moreover, to our knowledge, almost no literature has proposed the effective and
applied method to select the optimal kernel width for faulty RBF neural networks. As is known that the node faults inevitably
take place in real applications, which results in a great many of faulty networks, it will take a lot of time to calculate
the mean prediction error (MPE) for the traditional method, i.e., the test set method. Thus, the letter derives a formula
to estimate the MPE of each candidate width value and then use it to select the optimal one with the lowest MPE value for
faulty RBF neural networks with multi-node open fault. Simulation results show that the chosen optimal kernel width by our
proposed MPE formula is very close to the actual one by the conventional method. Moreover, our proposed MPE formula outperforms
other selection methods used for fault-free neural networks. 相似文献
145.
Squeeze-film damping on microresonators is a significant damping source even when the surrounding gas is highly rarefied. This article presents a general modeling approach based on Monte Carlo (MC) simulations for the prediction of squeeze-film damping on resonators in the free-molecule regime. The generality of the approach is demonstrated in its capability of simulating resonators of any shape and with any accommodation coefficient. The approach is validated using both the analytical results of the free-space damping and the experimental data of the squeeze-film damping on a clamped–clamped plate resonator oscillating at its first flexure mode. The effect of oscillation modes on the quality factor of the resonator has also been studied and semi-analytical approximate models for the squeeze-film damping with diffuse collisions have been developed. 相似文献
146.
Bert W. Leung Author Vitae Author Vitae Duncan S. Wong Author Vitae 《Pattern recognition》2009,42(5):929-940
Hou [Visual cryptography for color images, Pattern Recognition 36 (2003) 1619-1629] proposed a four-share visual cryptography scheme for color images. The scheme splits a dithered eight-color secret image into four shares: the black mask and other three shares. It was claimed that without knowing the black mask, no information about the secret image can be obtained even if all the other three shares are known. In this paper, we show that this may be true for a few specific two-color secret images only. In all other cases, however, security cannot be guaranteed. We show that an attacker can compromise a randomly chosen two-color secret image from any two of the other three shares with probability by completely recovering the shape and pattern of the secret image. The advantage will increase to if all the three shares are known. If the secret image has three or four colors, we show that the attacker can compromise it with probability and , respectively. Finally, we show that our technique can be extended to compromising secret images with more than four colors. 相似文献
147.
Yuming Zhou Leung H. Baowen Xu 《IEEE transactions on pattern analysis and machine intelligence》2009,35(5):607-623
Previous research shows that class size can influence the associations between object-oriented (OO) metrics and fault-proneness and therefore proposes that it should be controlled as a confounding variable when validating OO metrics on fault-proneness. Otherwise, their true associations may be distorted. However, it has not been determined whether this practice is equally applicable to other external quality attributes. In this paper, we use three size metrics, two of which are available during the high-level design phase, to examine the potentially confounding effect of class size on the associations between OO metrics and change-proneness. The OO metrics that are investigated include cohesion, coupling, and inheritance metrics. Our results, based on Eclipse, indicate that: 1) The confounding effect of class size on the associations between OO metrics and change-proneness, in general, exists, regardless of whichever size metric is used; 2) the confounding effect of class size generally leads to an overestimate of the associations between OO metrics and change-proneness; and 3) for many OO metrics, the confounding effect of class size completely accounts for their associations with change-proneness or results in a change of the direction of the associations. These results strongly suggest that studies validating OO metrics on change-proneness should also consider class size as a confounding variable. 相似文献
148.
149.
Multimedia Tools and Applications - Rapid population aging and advances in sensing technologies motivate the development of unobtrusive healthcare systems, designed to unobtrusively collect an... 相似文献
150.
Prediction of noisy chaotic time series using an optimal radialbasis function neural network 总被引:6,自引:0,他引:6
Henry Leung Titus Lo Sichun Wang 《Neural Networks, IEEE Transactions on》2001,12(5):1163-1172
This paper considers the problem of optimum prediction of noisy chaotic time series using a basis function neural network, in particular, the radial basis function (RBF) network. In the noiseless environment, predicting a chaotic time series is equivalent to approximating a nonlinear function. The optimal generalization is achieved when the number of hidden units of a RBF predictor approaches infinity. When noise exists, it is shown that an optimal RBF predictor should use a finite number of hidden units. To determine the structure of an optimal RBF predictor, we propose a new technique called the cross-validated subspace method to estimate the optimum number of hidden units. While the subspace technique is used to identify a suitable number of hidden units by detecting the dimension of the subspace spanned by the signal eigenvectors, the cross validation method is applied to prevent the problem of overfitting. The effectiveness of this new method is evaluated using simulated noisy chaotic time series as well as real-life oceanic radar signals. Results show that the proposed method can find the correct number of hidden units of an RBF network for an optimal prediction. 相似文献