全文获取类型
收费全文 | 3077篇 |
免费 | 132篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 86篇 |
综合类 | 13篇 |
化学工业 | 439篇 |
金属工艺 | 55篇 |
机械仪表 | 70篇 |
建筑科学 | 137篇 |
矿业工程 | 3篇 |
能源动力 | 127篇 |
轻工业 | 231篇 |
水利工程 | 29篇 |
石油天然气 | 8篇 |
武器工业 | 1篇 |
无线电 | 619篇 |
一般工业技术 | 503篇 |
冶金工业 | 482篇 |
原子能技术 | 25篇 |
自动化技术 | 388篇 |
出版年
2023年 | 16篇 |
2022年 | 55篇 |
2021年 | 42篇 |
2020年 | 27篇 |
2019年 | 35篇 |
2018年 | 53篇 |
2017年 | 61篇 |
2016年 | 58篇 |
2015年 | 67篇 |
2014年 | 119篇 |
2013年 | 193篇 |
2012年 | 156篇 |
2011年 | 187篇 |
2010年 | 128篇 |
2009年 | 129篇 |
2008年 | 149篇 |
2007年 | 121篇 |
2006年 | 128篇 |
2005年 | 98篇 |
2004年 | 88篇 |
2003年 | 76篇 |
2002年 | 84篇 |
2001年 | 67篇 |
2000年 | 65篇 |
1999年 | 77篇 |
1998年 | 191篇 |
1997年 | 133篇 |
1996年 | 78篇 |
1995年 | 71篇 |
1994年 | 61篇 |
1993年 | 65篇 |
1992年 | 36篇 |
1991年 | 24篇 |
1990年 | 37篇 |
1989年 | 22篇 |
1988年 | 22篇 |
1987年 | 16篇 |
1986年 | 8篇 |
1985年 | 18篇 |
1984年 | 13篇 |
1983年 | 12篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1980年 | 14篇 |
1979年 | 8篇 |
1978年 | 9篇 |
1975年 | 14篇 |
1974年 | 9篇 |
1972年 | 9篇 |
1965年 | 6篇 |
排序方式: 共有3216条查询结果,搜索用时 15 毫秒
81.
Ping Wang Kuo-Ming Chao Chi-Chun Lo Yu-Shih Wang 《Information Technology and Management》2017,18(1):1-25
Existing studies on the detection of mobile malware have focused mainly on static analyses performed to examine the code-structure signature of viruses, rather than the dynamic behavioral aspects. By contrast, the unidentified behavior of new mobile viruses using the self-modification, polymorphic, and mutation techniques for variants have largely been ignored. The problem of precision regarding malware variant detection has become one of the key concerns in mobile security. Accordingly, the present study proposed a threat risk analysis model for mobile viruses, using a heuristic approach incorporating both malware behavior analysis and code analysis to generate a virus behavior ontology associated with the Protégé platform. The proposed model can not only explicitly identify an attack profile in accordance with structural signature of mobile viruses, but also overcome the uncertainty regarding the probability of an attack being successful. This model is able to achieve this by extending frequent episode rules to investigate the attack profile of a given malware, using specific event sequences associated with the sandbox technique for mobile applications (apps) and hosts. For probabilistic analysis, defense evaluation metrics for each node were used to simulate the results of an attack. The simulations focused specifically on the attack profile of a botnet to assess the threat risk. The validity of the proposed approach was demonstrated numerically by using two malware cyber-attack examples. Overall, the results presented in this paper prove that the proposed scheme offers an effective countermeasure, evaluated using a set of security metrics, for mitigating network threats by considering the interaction between the attack profiles and defense needs. 相似文献
82.
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
83.
84.
85.
Background subtraction or temporal differencing is commonly applied on an image sequence for foreground/background segmentation. However, cast shadows of moving foreground objects in a scene often result in detection errors for many vision-based applications. To address this problem, the authors propose an algorithm exploiting the information of colour, shading, texture, neighbourhood and temporal consistency to detect shadows efficiently and adaptively. The experimental results show that the proposed method can detect the penumbra as well as the umbra in different kinds of scenarios under various illumination conditions. 相似文献
86.
P Kahane L Tassi S Francione D Hoffmann G Lo Russo C Munari 《Canadian Metallurgical Quarterly》1993,23(4):305-326
In patients with severe drug-resistant partial epilepsy, undergoing Stereo-EEG investigations, spatial definition of the "epileptogenic area" is mainly based on spontaneous seizures recordings, but also on seizures induced by intracerebral electrical stimulation (ES). Only "trains" ES (TES, 50 pps) are currently used with this aim; "shocks" ES (SES, 1 pps) are principally applied to localize motor pathways. We have shown, during a prospective study concerning 10 temporal lobe epileptic patients, that SES could frequently induce seizures, especially when stimulation is applied in the anterior part of the Ammon's horn. Even if its efficacy seems lower than by TES, this kind of stimulation, in the majority of the cases, does reproduce isolated ictal subjective symptomatology, allowing the visualization of the progressive organisation of ictal electrical discharges, and avoids "unexpected" ("false positive"?) clinical responses. 相似文献
87.
Cobra neurotoxin from Formosan cobra (Naja naja atra) venom is a compact globular protein having an intrinsic viscosity of 4.5 mL/g. The protein is stable in 7.5 M urea but can be denatured in 4.1 M guanidine hydrochloride or at elevated temperature (above 70 degrees C). Its conformation remains virtually the same in solvents of lower polarity than water such as 1,2-ethanediol or a mixed solvent of 1-propanol-1,2-ethanediol-water (5:1:1 by volume). The circular dichroism spectrum is "atypical" in water in that the peptide chromophores show a small negative circular dichroic (CD) band at 215 nm, a large positive one at 199 nm, and another large negative one below 190 nm. The CD pattern resembles to some extent that of a beta form but differs in both positions and magnitudes from the latter. It agrees qualitatively with the theoretical calculations of the reverse beta bends, suggesting that cobra toxin contains a considerable amount of beta turns and possibly a mixture of beta form and beta turns. 相似文献
88.
89.
A number of techniques that infer finite state automata from execution traces have been used to support test and analysis activities. Some of these techniques can produce automata that integrate information about the data-flow, that is, they also represent how data values affect the operations executed by programs.The integration of information about operation sequences and data values into a unique model is indeed conceptually useful to accurately represent the behavior of a program. However, it is still unclear whether handling heterogeneous types of information, such as operation sequences and data values, necessarily produces higher quality models or not.In this paper, we present an empirical comparative study between techniques that infer simple automata and techniques that infer automata extended with information about data-flow. We investigate the effectiveness of these techniques when applied to traces with different levels of sparseness, produced by different software systems. To the best of our knowledge this is the first work that quantifies both the effect of adding data-flow information within automata and the effectiveness of the techniques when varying sparseness of traces. 相似文献
90.
Shu-Kai S. Fan Le-Chun Lo Yuan-Jung Chang Chen-ju Lin Fugee Tsung 《Journal of Process Control》2012,22(4):823-828
This paper investigates how to adaptively predict the time-varying metrology delay that can realistically occur in the semiconductor manufacturing practice. In the presence of metrology delays, the expected asymptotic double exponentially weighted moving average (dEWMA) control output, by using the EWMA and recursive least squares prediction methods, is derived. It has been found that the relationships between the expected control output and target in both estimation methods are equivalent, and six cases are addressed. Within the context of time-varying metrology delay, a new time update scheme to the recursive least squares-linear trend (RLS-LT) controller, combined with zone tests and the moving average (MA) control chart, is proposed. Simulated single input–single output (SISO) run-to-run processes subject to two time-varying metrology delay scenarios are used to assess the effectiveness of the proposed controller. 相似文献