全文获取类型
收费全文 | 2661篇 |
免费 | 151篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 28篇 |
化学工业 | 816篇 |
金属工艺 | 56篇 |
机械仪表 | 80篇 |
建筑科学 | 91篇 |
矿业工程 | 21篇 |
能源动力 | 85篇 |
轻工业 | 196篇 |
水利工程 | 18篇 |
石油天然气 | 8篇 |
武器工业 | 1篇 |
无线电 | 220篇 |
一般工业技术 | 521篇 |
冶金工业 | 160篇 |
原子能技术 | 33篇 |
自动化技术 | 490篇 |
出版年
2023年 | 31篇 |
2022年 | 122篇 |
2021年 | 116篇 |
2020年 | 86篇 |
2019年 | 65篇 |
2018年 | 97篇 |
2017年 | 100篇 |
2016年 | 97篇 |
2015年 | 92篇 |
2014年 | 128篇 |
2013年 | 209篇 |
2012年 | 154篇 |
2011年 | 180篇 |
2010年 | 132篇 |
2009年 | 124篇 |
2008年 | 134篇 |
2007年 | 102篇 |
2006年 | 89篇 |
2005年 | 82篇 |
2004年 | 59篇 |
2003年 | 56篇 |
2002年 | 48篇 |
2001年 | 30篇 |
2000年 | 27篇 |
1999年 | 28篇 |
1998年 | 39篇 |
1997年 | 23篇 |
1996年 | 19篇 |
1995年 | 25篇 |
1994年 | 24篇 |
1993年 | 23篇 |
1992年 | 16篇 |
1991年 | 18篇 |
1990年 | 11篇 |
1989年 | 13篇 |
1988年 | 13篇 |
1987年 | 24篇 |
1986年 | 15篇 |
1985年 | 15篇 |
1984年 | 13篇 |
1983年 | 9篇 |
1982年 | 16篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1976年 | 7篇 |
1975年 | 9篇 |
1974年 | 7篇 |
1973年 | 13篇 |
1972年 | 8篇 |
排序方式: 共有2824条查询结果,搜索用时 62 毫秒
81.
Hao WangAuthor VitaeJens B. SchmittAuthor Vitae Ivan MartinovicAuthor Vitae 《Performance Evaluation》2011,68(2):201-219
During the last two decades, starting with the seminal work by Cruz, network calculus has evolved as a new theory for the performance analysis of networked systems. In contrast to classical queueing theory, it deals with performance bounds instead of average values and thus has been the theoretical basis of quality of service proposals such as the IETF’s Integrated and Differentiated Services architectures. Besides these it has, however, recently seen many other application scenarios as, for example, wireless sensor networks, switched Ethernets, avionic networks, Systems-on-Chip, or even to speed-up simulations, to name a few.In this article, we extend network calculus by adding a new versatile modeling element: a demultiplexer. Conventionally, demultiplexing has been either neglected or assumed to be static, i.e., fixed at the setup time of a network. This is restrictive for many potential applications of network calculus. For example, a load balancing based on current link loads in a network could not be modeled with conventional network calculus means. Our demultiplexing element is based on stochastic scaling. Stochastic scaling allows one to put probabilistic bounds on how a flow is split inside the network. Fundamental results on network calculus with stochastic scaling are therefore derived in this work. We illustrate the benefits of the demultiplexer in a sample application of uncertain load balancing. 相似文献
82.
In the area of membrane computing, time-freeness has been defined as the ability for a timed membrane system to produce always
the same result, independently of the execution times associated to the rules. In this paper, we use a similar idea in the
framework of spiking neural P systems, a model inspired by the structure and the functioning of neural cells. In particular,
we introduce stochastic spiking neural P systems where the time of firing for an enabled spiking rule is probabilistically
chosen and we investigate when, and how, these probabilities can influence the ability of the systems to simulate, in a reliable
way, universal machines, such as register machines. 相似文献
83.
Ivan Marsa-Maestre Miguel A. Lopez-Carmona Juan R. Velasco 《Service Oriented Computing and Applications》2008,2(4):167-185
Service Oriented Architectures, which allow for the integration of different subsystems and of applications running on different
devices and platforms, may be very suitable to solve the problem of service personalization in large smart environments like
cities, where the number of potential users and potentially available services is rapidly growing. Taking this into account,
we have designed an agent-based service oriented architecture for smart spaces. Two of the greatest challenges in the design
of such a solution are providing effective device, service and context federation and composition mechanisms and handling
user mobility. For the first challenge, we have designed a hierarchical architecture and developed a set of inheritance, aggregation
and access mechanisms for devices, services and context. To handle user mobility, we have followed three different strategies,
using stationary, mobile or nomadic agents. In this paper, we describe the main aspects of our architecture and perform an experimental evaluation to determine
the advantages and drawbacks of the different strategies. 相似文献
84.
Jovanović I Ugrenović S Antić S Stefanović N Mihailović D 《Microscopy research and technique》2007,70(7):617-627
Psammoma bodies (PBs) are one of many choroids plexus aging changes. The aim of our research was to perform the quantification of PBs' presence in human choroids plexus stroma, as well as to evaluate the characteristics of choroids plexus stroma in cases in which PBs were present. Afterwards, the observations of the histochemical analysis would be confirmed by immunohistochemical analysis. Choroid plexuses of 30 cadavers were used for the histochemical and, choroids plexuses of 15 cadavers in which PBs' presence was confirmed during the histochemical analysis, were used as material for the immunohistochemical analysis. Light microscopy, histochemical, immunohistochemical, and morphometric method were applied during the study. Classification of the cases was performed by cluster analysis. We observed increase of choroids plexus PBs' presence during the aging process. But this increase is not linear. Their presence is the largest in the second cluster that is younger than the third and older than the first. Nuclear morphometric parameters of the stroma in these cases showed that the cellular composition in this cluster is different than in other two and, that contain larger number of lymphoid cells. Immunohistochemical analysis showed PBs' positive reaction on vimentin, CD45R0, and LCA markers, while in their vicinity, as well as inside them, numerous T-cells were observed. So, the presence of CD45R0 and LCA-positive T cells, PBs' positive reaction on the same markers, indirectly connect these cells with PBs' formation process. 相似文献
85.
Ivan Bozovic 《Journal of Superconductivity》1991,4(2):193-197
A novel optical method for accurate monitoring of the carrier densityN in layered conductors is introduced. It is applied to several cuprate superconductors, and it is found thatT
c
doesnot scale withN. However, if the closely spaced pairs or triplets of CuO2 planes were coupled together to act as distinct metallic slabs, the relevant variable could ben, theslab carrier density. Indeed, we found thatT
c
does scale nicely withn. This suggests that high-T
c
superconductivity is effectively a two-dimensional phenomenon; it can occur in a cuprate slab which is only one unit cell thick. Finally, estimates are obtained for the length scales of localization of charge carriers:d 8 Å andd
2 Å in all the cuprates under study. 相似文献
86.
Linda A. Jackson Edward A. Witt Alexander Ivan Games Hiram E. Fitzgerald Alexander von Eye Yong Zhao 《Computers in human behavior》2012
This research examined relationships between children’s information technology (IT) use and their creativity. Four types of information technology were considered: computer use, Internet use, videogame playing and cell phone use. A multidimensional measure of creativity was developed based on and test of creative thinking. Participants were 491 12-year olds; 53% were female, 34% were African American and 66% were Caucasian American. Results indicated that videogame playing predicted of all measures of creativity. Regardless of gender or race, greater videogame playing was associated with greater creativity. Type of videogame (e.g., violent, interpersonal) was unrelated to videogame effects on creativity. Gender but not race differences were obtained in the amount and type of videogame playing, but not in creativity. Implications of the findings for future research to test the causal relationship between videogame playing and creativity and to identify mediator and moderator variables are discussed. 相似文献
87.
Stephen Muggleton Luc De Raedt David Poole Ivan Bratko Peter Flach Katsumi Inoue Ashwin Srinivasan 《Machine Learning》2012,86(1):3-23
Inductive Logic Programming (ILP) is an area of Machine Learning which has now reached its twentieth year. Using the analogy
of a human biography this paper recalls the development of the subject from its infancy through childhood and teenage years.
We show how in each phase ILP has been characterised by an attempt to extend theory and implementations in tandem with the
development of novel and challenging real-world applications. Lastly, by projection we suggest directions for research which
will help the subject coming of age. 相似文献
88.
Peter Sussner Estev?o L. Esmi Ivan Villaverde Manuel Gra?a 《Journal of Mathematical Imaging and Vision》2012,42(2-3):134-149
Many well-known fuzzy associative memory (FAM) models can be viewed as (fuzzy) morphological neural networks (MNNs) because they perform an operation of (fuzzy) mathematical morphology at every node, possibly followed by the application of an activation function. The vast majority of these FAMs represent distributive models given by single-layer matrix memories. Although the Kosko subsethood FAM (KS-FAM) can also be classified as a fuzzy morphological associative memory (FMAM), the KS-FAM constitutes a two-layer non-distributive model. In this paper, we prove several theorems concerning the conditions of perfect recall, the absolute storage capacity, and the output patterns produced by the KS-FAM. In addition, we propose a normalization strategy for the training and recall phases of the KS-FAM. We employ this strategy to compare the error correction capabilities of the KS-FAM and other fuzzy and gray-scale associative memories in terms of some experimental results concerning gray-scale image reconstruction. Finally, we apply the KS-FAM to the task of vision-based self-localization in robotics. 相似文献
89.
Fengmin Le Ivan MarkovskyChristopher T. Freeman Eric Rogers 《Control Engineering Practice》2012,20(4):386-396
Modeling of electrically stimulated muscle is considered in this paper where a Hammerstein structure is selected to represent the isometric response. Motivated by the slowly time-varying properties of the muscle system, recursive identification of Hammerstein structures is investigated. A recursive algorithm is then developed to address limitations in the approaches currently available. The linear and nonlinear parameters are separated and estimated recursively in a parallel manner, with each updating algorithm using the most up-to-date estimation produced by the other algorithm at each time instant. Hence the procedure is termed the alternately recursive least square (ARLS) algorithm. When compared with the leading approach in this application area, ARLS exhibits superior performance in both numerical simulations and experimental tests with electrically stimulated muscle. 相似文献
90.
M. Jergel T. Melíšek H Allárová D. I. Belyj V. P. Kutepov A. J. Izrailev D. Synak J. Neuschl J. Ivan 《Journal of Materials Science》1982,17(6):1579-1584
The influence of the presence of oxygen in the Nb-Zr substrate upon some physical and mechanical properties of the Nb-ZrO2 substrate and/or Nb3Sn tape superconductor prepared from such a substrate has been studied. The results have shown that the Nb3Sn grains are much finer in the case of Nb-ZrO2, than those obtained on Nb-Zr substrate. As a result, both the electrical and mechanical properties have been substantially improved. The critical current at a field of 5 T increased by between 100 and 200 %, the alternating current losses decreased by about one order of magnitude, the tensile strength increased by about a factor of three and the microhardness value also increased by about a factor of three for oxygen contents in the range 0.03 to 0.70 wt%. The specific resistance of this substrate increased at the same time from 17 to 22 cm and the relative elongation decreased from 5 to 3 %. 相似文献