全文获取类型
收费全文 | 1854篇 |
免费 | 51篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 13篇 |
综合类 | 3篇 |
化学工业 | 449篇 |
金属工艺 | 44篇 |
机械仪表 | 27篇 |
建筑科学 | 38篇 |
能源动力 | 93篇 |
轻工业 | 137篇 |
水利工程 | 8篇 |
石油天然气 | 14篇 |
无线电 | 161篇 |
一般工业技术 | 244篇 |
冶金工业 | 397篇 |
原子能技术 | 12篇 |
自动化技术 | 270篇 |
出版年
2022年 | 24篇 |
2021年 | 42篇 |
2020年 | 35篇 |
2019年 | 23篇 |
2018年 | 44篇 |
2017年 | 35篇 |
2016年 | 35篇 |
2015年 | 25篇 |
2014年 | 32篇 |
2013年 | 94篇 |
2012年 | 67篇 |
2011年 | 100篇 |
2010年 | 73篇 |
2009年 | 67篇 |
2008年 | 81篇 |
2007年 | 69篇 |
2006年 | 48篇 |
2005年 | 31篇 |
2004年 | 40篇 |
2003年 | 30篇 |
2002年 | 50篇 |
2001年 | 38篇 |
2000年 | 37篇 |
1999年 | 33篇 |
1998年 | 94篇 |
1997年 | 58篇 |
1996年 | 50篇 |
1995年 | 41篇 |
1994年 | 39篇 |
1993年 | 37篇 |
1992年 | 28篇 |
1991年 | 19篇 |
1990年 | 24篇 |
1989年 | 25篇 |
1988年 | 34篇 |
1987年 | 21篇 |
1986年 | 17篇 |
1985年 | 27篇 |
1984年 | 22篇 |
1983年 | 20篇 |
1982年 | 19篇 |
1981年 | 14篇 |
1980年 | 14篇 |
1979年 | 11篇 |
1978年 | 18篇 |
1977年 | 13篇 |
1976年 | 25篇 |
1974年 | 13篇 |
1973年 | 14篇 |
1969年 | 10篇 |
排序方式: 共有1910条查询结果,搜索用时 18 毫秒
51.
The bottleneck network flow problem (BNFP) is a generalization of several well-studied bottleneck problems such as the bottleneck transportation problem (BTP), bottleneck assignment problem (BAP), bottleneck path problem (BPP), and so on. The BNFP can easily be solved as a sequence of O(logn) maximum flow problems on almost unit capacity networks. We observe that this algorithm runs in O(min{m3/2,n2/3m}logn) time by showing that the maximum flow problem on an almost unit capacity graph can be solved in O(min{m3/2,n2/3m}) time. We then propose a faster algorithm to solve the unit capacity BNFP in time, an improvement by a factor of at least . For dense graphs, the improvement is by a factor of . On unit capacity simple graphs, we show that BNFP can be solved in time, an improvement by a factor of . As a consequence we have an algorithm for the BTP with unit arc capacities. 相似文献
52.
Abraham Robin Erwig Martin 《IEEE transactions on pattern analysis and machine intelligence》2009,35(1):94-108
Based on (1) research into mutation testing for general purpose programming languages, and (2) spreadsheet errors that have been reported in the literature, we have developed a suite of mutation operators for spreadsheets. We present an evaluation of the mutation adequacy of du-adequate test suites generated by a constraint-based automatic test-case generation system we have developed in previous work. The results of the evaluation suggest additional constraints that can be incorporated into the system to target mutation adequacy. In addition to being useful in mutation testing of spreadsheets, the operators can be used in the evaluation of error-detection tools and also for seeding spreadsheets with errors for empirical studies. We describe two case studies where the suite of mutation operators helped us carry out such empirical evaluations. The main contribution of this paper is a suite of mutation operators for spreadsheets that can be used for carrying out empirical evaluations of spreadsheet tools to indicate ways in which the tools can be improved. 相似文献
53.
Organizational Learning Mechanisms and Creative Climate: Insights from an Italian Fashion Design Company
下载免费PDF全文
![点击此处可从《Creativity & Innovation Management》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Stefano Cirella Filomena Canterino Marco Guerci Abraham B. Shani 《Creativity & Innovation Management》2016,25(2):211-222
This paper investigates the relationship between different types of organizational learning mechanisms and creative climate. In the context of an action research study, this paper focuses on insights from a survey that was administered to all the employees of the Product Design and Development unit of the company. The results demonstrate that the three different types of organizational learning mechanisms considered in the study (cognitive, structural and procedural mechanisms) are associated with creative climate. The study generates new scientific knowledge about the role of organizational learning mechanisms and provides specific recommendations for organizations that aim to enhance creative climate. 相似文献
54.
Marya Wani Vishnupriya Raghavan Dolphy Abraham Virginia Kleist 《Information Systems Frontiers》2017,19(4):769-785
Travel websites are extensively used by travelers for their travel bookings, yet little is known about the hedonic effectiveness of such experiences for the customer. The end users of these websites are customers who may not always be sophisticated information system (IS) users. Further, traditional utility based measures of customer evaluation are dated with respect to the interactive nature of the technology in use and the hedonic benefits that may result from the use of the technology. The evaluation of IS needs to include hedonic measures facilitated by the interactive technology in addition to the traditional utility based measures. We propose and test an evaluation model for retail travel websites that combines the traditional utility based measures with hedonic measures which collectively create a more comprehensive measure for the IS evaluation of consumer focused websites. Thus rooted in theory, the model extends DeLone and McLean’s model of IS Success by adding the construct of User Experience. The model was tested on a sample of 255 customers of travel websites targeted at the Indian market. The results indicate that both utility based and hedonic measures are important factors for customer IS (travel website in this study) evaluation. The larger implications for theory and practice of IS evaluation are explained. 相似文献
55.
Özden Engin Çak?c? Harry Groenevelt Abraham SeidmannAuthor vitae 《Decision Support Systems》2011,51(4):842-852
Motivated by a case study at a radiology practice, we analyze the incremental benefits of RFID technology over barcodes for managing pharmaceutical inventories. Unlike barcode technology, RFID enables accurate real-time visibility, which in turn enables several process improvements. We analyze the impact of automatic counting and discuss the system redesign critical to optimizing the inventory policy and eliminating shrinkage. We show that continuous review is superior to periodic review whenever accurate real-time information is available at no additional cost. We explain how RFID-enabled strategies vary with inventory parameters and provide a cost-benefit analysis for the implementation of RFID for the radiology practice. 相似文献
56.
This paper revisits the problem of wireframe rendering, which, at first, appears to be an easily solved problem. However, the conventional solution is inefficient and does not result in high-quality images. Recently, graphics hardware programming has been employed to achieve high-quality solid line rendering. In this paper, we present a simpler and faster technique for wireframe rendering based on texture mapping. Our technique does not require (but can benefit from) graphics hardware programming and thus can be easily integrated into existing rendering engines, while resulting in fast, accurate, high-quality, anti-aliased, and still versatile, wireframe drawing. For topologically structured meshes, our approach allows the rendering of wireframe decoupled from the underlying mesh, making possible the rendering of original wireframes on top of decimated meshes. 相似文献
57.
Density functional calculations and minimization techniques have been employed to characterize the structural and electronic properties of [5,6]-heterofullerene-C58Si-C2v. Since it has odd number of atoms and a near planar tetracoordinate Si atom on the skeleton of the cage, it has odd number of atoms assembling a cage and is a novel molecule. Vibrational frequencies of the molecule have been calculated at the B3LYP/6-31G* level of theory. The absence of imaginary vibrational frequency confirms that the molecule corresponds to a true minimum on the potential energy hypersurface. Sixteen 13C nuclear magnetic resonance (NMR) spectral signals of C58Si are characterized, and its heat of formation was estimated in this work. 相似文献
58.
Das S. Abraham A. Konar A. 《IEEE transactions on systems, man, and cybernetics. Part A, Systems and humans : a publication of the IEEE Systems, Man, and Cybernetics Society》2008,38(1):218-237
Differential evolution (DE) has emerged as one of the fast, robust, and efficient global search heuristics of current interest. This paper describes an application of DE to the automatic clustering of large unlabeled data sets. In contrast to most of the existing clustering techniques, the proposed algorithm requires no prior knowledge of the data to be classified. Rather, it determines the optimal number of partitions of the data "on the run." Superiority of the new method is demonstrated by comparing it with two recently developed partitional clustering techniques and one popular hierarchical clustering algorithm. The partitional clustering algorithms are based on two powerful well-known optimization algorithms, namely the genetic algorithm and the particle swarm optimization. An interesting real-world application of the proposed method to automatic segmentation of images is also reported. 相似文献
59.
Granular neural networks for numerical-linguistic data fusion andknowledge discovery 总被引:1,自引:0,他引:1
Yan-Qing Zhang Fraser M.D. Gagliano R.A. Kandel A. 《Neural Networks, IEEE Transactions on》2000,11(3):658-667
We present a neural-networks-based knowledge discovery and data mining (KDDM) methodology based on granular computing, neural computing, fuzzy computing, linguistic computing, and pattern recognition. The major issues include 1) how to make neural networks process both numerical and linguistic data in a database, 2) how to convert fuzzy linguistic data into related numerical features, 3) how to use neural networks to do numerical-linguistic data fusion, 4) how to use neural networks to discover granular knowledge from numerical-linguistic databases, and 5) how to use discovered granular knowledge to predict missing data. In order to answer the above concerns, a granular neural network (GNN) is designed to deal with numerical-linguistic data fusion and granular knowledge discovery in numerical-linguistic databases. From a data granulation point of view the GNN can process granular data in a database. From a data fusion point of view, the GNN makes decisions based on different kinds of granular data. From a KDDM point of view the GNN is able to learn internal granular relations between numerical-linguistic inputs and outputs, and predict new relations in a database. The GNN is also capable of greatly compressing low-level granular data to high-level granular knowledge with some compression error and a data compression rate. To do KDDM in huge databases, parallel GNN and distributed GNN will be investigated in the future. 相似文献
60.
Considerations of metropolitan commuting have often related to urban space as a continuum, and to commuting itself as a process. This approach has led to escalating complexity in the measurement, modeling and analysis of commuting, often with no commensurate results. The present study extends an alternative approach that considers commuter space of a metropolis as a discrete set of small areas. Each small area throughout the metropolis is a nighttime location of some households and, as a possible discrete destination choice of individuals within households, each subarea is also a daytime location of some persons. Each subarea, therefore, may be thought of as attaining two values, corresponding to its daytime (e.g., noontime) and nighttime (e.g., midnight) populations. The diurnal demographic shift of subareas, as a set of binary events, or toggles, between daytime and nighttime populations, is associated with commuter access throughout the metropolis. Diurnal shift offers structural simplicity aimed at estimating small-area daytime populations across a metropolitan region that might suitably precede and complement conventional continuum considerations of commuting. Using data for the Tokyo Metropolitan Region, we identify average household size as the nighttime indicator of small-areas, and daytime population density as their daytime indicator. The potential for the estimation of daytime populations across metropolitan regions where daytime population data are unavailable, is underscored by the clear tendency towards inverse relation of these two indicators of diurnal shift. 相似文献