全文获取类型
收费全文 | 84529篇 |
免费 | 1071篇 |
国内免费 | 408篇 |
专业分类
电工技术 | 785篇 |
综合类 | 2318篇 |
化学工业 | 11545篇 |
金属工艺 | 4815篇 |
机械仪表 | 3098篇 |
建筑科学 | 2171篇 |
矿业工程 | 562篇 |
能源动力 | 1156篇 |
轻工业 | 3683篇 |
水利工程 | 1268篇 |
石油天然气 | 342篇 |
无线电 | 9432篇 |
一般工业技术 | 16471篇 |
冶金工业 | 2679篇 |
原子能技术 | 263篇 |
自动化技术 | 25420篇 |
出版年
2023年 | 24篇 |
2022年 | 21篇 |
2021年 | 31篇 |
2020年 | 32篇 |
2019年 | 39篇 |
2018年 | 14474篇 |
2017年 | 13394篇 |
2016年 | 9990篇 |
2015年 | 638篇 |
2014年 | 287篇 |
2013年 | 276篇 |
2012年 | 3201篇 |
2011年 | 9468篇 |
2010年 | 8326篇 |
2009年 | 5603篇 |
2008年 | 6818篇 |
2007年 | 7804篇 |
2006年 | 151篇 |
2005年 | 1242篇 |
2004年 | 1155篇 |
2003年 | 1196篇 |
2002年 | 563篇 |
2001年 | 121篇 |
2000年 | 189篇 |
1999年 | 69篇 |
1998年 | 73篇 |
1997年 | 35篇 |
1996年 | 59篇 |
1995年 | 22篇 |
1994年 | 17篇 |
1993年 | 12篇 |
1992年 | 15篇 |
1991年 | 26篇 |
1988年 | 14篇 |
1969年 | 24篇 |
1968年 | 43篇 |
1967年 | 33篇 |
1966年 | 42篇 |
1965年 | 44篇 |
1964年 | 11篇 |
1963年 | 28篇 |
1962年 | 22篇 |
1961年 | 18篇 |
1960年 | 30篇 |
1959年 | 35篇 |
1958年 | 37篇 |
1957年 | 36篇 |
1956年 | 34篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Ouiem Bchir Hichem Frigui Mohamed Maher Ben Ismail 《Pattern Analysis & Applications》2016,19(4):919-937
We propose a new relational clustering approach, called Fuzzy clustering with Learnable Cluster-dependent Kernels (FLeCK), that learns the underlying cluster-dependent dissimilarity measure while seeking compact clusters. The learned dissimilarity is based on a Gaussian kernel function with cluster-dependent parameters. Each cluster’s parameter learned by FLeCK reflects the relative intra-cluster and inter-cluster characteristics. These parameters are learned by optimizing both the intra-cluster and the inter-cluster distances. This optimization is achieved iteratively by dynamically updating the partition and the local kernel. This makes the kernel learning task takes advantages of the available unlabeled data and reciprocally, the categorization task takes advantages of the learned local kernels. Another key advantage of FLeCK is that it is formulated to work on relational data. This makes it applicable to data where objects cannot be represented by vectors or when clusters of similar objects cannot be represented efficiently by a single prototype. Using synthetic and real data sets, we show that FLeCK learns meaningful parameters and outperforms several other algorithms. In particular, we show that when data include clusters with various inter- and intra-cluster distances, learning cluster-dependent parameters is crucial in obtaining a good partition. 相似文献
992.
Nikolaos Gianniotis Christoph Schnörr Christian Molkenthin Sanjay Singh Bora 《Pattern Analysis & Applications》2016,19(2):475-485
Variational methods are employed in situations where exact Bayesian inference becomes intractable due to the difficulty in performing certain integrals. Typically, variational methods postulate a tractable posterior and formulate a lower bound on the desired integral to be approximated, e.g. marginal likelihood. The lower bound is then optimised with respect to its free parameters, the so-called variational parameters. However, this is not always possible as for certain integrals it is very challenging (or tedious) to come up with a suitable lower bound. Here, we propose a simple scheme that overcomes some of the awkward cases where the usual variational treatment becomes difficult. The scheme relies on a rewriting of the lower bound on the model log-likelihood. We demonstrate the proposed scheme on a number of synthetic and real examples, as well as on a real geophysical model for which the standard variational approaches are inapplicable. 相似文献
993.
994.
Ibrahim Abdelaziz Sherif Abdou Hassanin Al-Barhamtoshy 《Pattern Analysis & Applications》2016,19(4):1129-1141
The success of using Hidden Markov Models (HMMs) for speech recognition application has motivated the adoption of these models for handwriting recognition especially the online handwriting that has large similarity with the speech signal as a sequential process. Some languages such as Arabic, Farsi and Urdo include large number of delayed strokes that are written above or below most letters and usually written delayed in time. These delayed strokes represent a modeling challenge for the conventional left-right HMM that is commonly used for Automatic Speech Recognition (ASR) systems. In this paper, we introduce a new approach for handling delayed strokes in Arabic online handwriting recognition using HMMs. We also show that several modeling approaches such as context based tri-grapheme models, speaker adaptive training and discriminative training that are currently used in most state-of-the-art ASR systems can provide similar performance improvement for Hand Writing Recognition (HWR) systems. Finally, we show that using a multi-pass decoder that use the computationally less expensive models in the early passes can provide an Arabic large vocabulary HWR system with practical decoding time. We evaluated the performance of our proposed Arabic HWR system using two databases of small and large lexicons. For the small lexicon data set, our system achieved competing results compared to the best reported state-of-the-art Arabic HWR systems. For the large lexicon, our system achieved promising results (accuracy and time) for a vocabulary size of 64k words with the possibility of adapting the models for specific writers to get even better results. 相似文献
995.
996.
The aim of this paper is to analyse the results of research carried out in the railway, mining, and electric power systems in Serbia and form a new integral control model. The three methodological procedures are applied. First, analytical-synthetic methodological approach breaks down complex technical system into three parts: bio-cybernetic system, “operator”; technical system, “technology”; and additional system, “working environment.” Second, network planning method is used to analyse time, according to the critical path method. Third, fuzzy analytic hierarchy process determines the key research factors. General results of research are new integral control model, and new research areas and activities. The most prominent factors are: in “bio-cybernetic system”—operator’s arm reach, body postures and movement sequences, operator’s work, occurrence of stress, and occurrence of fatigue; in “technical system”—location and dimension of control desk, display panel, video display terminal, symbols on video display terminal, colours in control centres, and suitability of the keyboards; and in “supporting system”—illumination in control centres and relative humidity. Based on the analysis of factors and synthesis of results, the following recommendation are proposed: new control desk design; new display panel design; new design of the main and local lighting; new illumination and contrast characteristics, and environmental impact assessment. For research on a variety of complex technical systems, new integral control model can be applied, with corresponding extensions. 相似文献
997.
Sanna Järvelä Paul A. Kirschner Allyson Hadwin Hanna Järvenoja Jonna Malmberg Mariel Miller Jari Laru 《International Journal of Computer-Supported Collaborative Learning》2016,11(3):263-280
The field of computer supported collaborative learning (CSCL) is progressing instrumentally and theoretically. Nevertheless, few studies examine the effectiveness and efficiency of CSCL with respect to cognitive, motivational, emotional, and social issues, despite the fact that the role of regulatory processes is critical for the quality of students’ engagement in collaborative learning settings. We review the four earlier lines in developing support in CSCL and show how there has been a lack of work to support individuals in groups to engage in, sustain, and productively regulate their own and the group’s collaborative processes. Our aim is to discuss how our conceptual work in socially shared regulation of learning (SSRL) contributes to effective and efficient CSCL, what tools are presently available, and what the implications of research on these tools are for future tool development. 相似文献
998.
This paper describes a method of finding the proper points for dividing a corpus with time series information to extract local and frequent keywords. Previous works have proposed the corpus separating method for extracting keywords from a corpus. However, this method divides a corpus at equal intervals so that it cannot consider the topic changes. The present paper utilizes the idea of the topic model and the topic extracted through latent Dirichlet allocation to consider the topic change. This paper identifies the points at which large topic changes occur to divide the corpus using structural change detection method. An experiment involving newspaper articles with 5-year topics confirm that the points at which the topics of each document change are detected to find the division points based on the idea of structural change point detection and our method is better than previous methods based on recall measure. 相似文献
999.
Frank Bonnet Yuta Kato José Halloy Francesco Mondada 《Artificial Life and Robotics》2016,21(3):239-246
Robotic fish are nowadays developed for various types of research, such as bio-inspiredrobotics, biomimetics and animal behavior studies. In the context of our research on the social interactions of the zebrafish Danio Rerio, we developed a miniature robotic fish lure for direct underwater interaction with the living fish. This remotely controlled and waterproof device has a total length of 7.5 cm with the same size ratio as zebrafish and is able to beat its tail with different frequencies and amplitudes, while following the group of living animals using a mobile robot moving outside water that is coupled with the robotic lure using magnets. The robotic lure is also equipped with a rechargeable battery and can be used autonomously underwater for experiments of up to 1 h. We performed experiments with the robot moving inside an aquarium with living fish to analyze its impact on the zebrafish behavior. We found that the beating rate of the tail increased the attractiveness of the lure among the zebrafish shoal. We also demonstrated that the lure could influence a collective decision of the zebrafish shoal, the swimming direction, when moving with a constant linear speed inside a circular corridor. This new robotic fish design and the experimental results are promising for the field of fish–robot interaction. 相似文献
1000.
Javier Arellano-Verdejo Enrique Alba Salvador Godoy-Calderon 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2016,20(3):895-905
Clustering algorithms, a fundamental base for data mining procedures and learning techniques, suffer from the lack of efficient methods for determining the optimal number of clusters to be found in an arbitrary dataset. The few methods existing in the literature always use some sort of evolutionary algorithm having a cluster validation index as its objective function. In this article, a new evolutionary algorithm, based on a hybrid model of global and local heuristic search, is proposed for the same task, and some experimentation is done with different datasets and indexes. Due to its design, independent of any clustering procedure, it is applicable to virtually any clustering method like the widely used \(k\)-means algorithm. Moreover, the use of non-parametric statistical tests over the experimental results, clearly show the proposed algorithm to be more efficient than other evolutionary algorithms currently used for the same task. 相似文献