全文获取类型
收费全文 | 1996篇 |
免费 | 162篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 30篇 |
综合类 | 1篇 |
化学工业 | 429篇 |
金属工艺 | 37篇 |
机械仪表 | 24篇 |
建筑科学 | 62篇 |
矿业工程 | 3篇 |
能源动力 | 78篇 |
轻工业 | 373篇 |
水利工程 | 15篇 |
石油天然气 | 5篇 |
无线电 | 152篇 |
一般工业技术 | 309篇 |
冶金工业 | 384篇 |
原子能技术 | 17篇 |
自动化技术 | 240篇 |
出版年
2023年 | 11篇 |
2022年 | 34篇 |
2021年 | 45篇 |
2020年 | 28篇 |
2019年 | 64篇 |
2018年 | 65篇 |
2017年 | 50篇 |
2016年 | 69篇 |
2015年 | 56篇 |
2014年 | 80篇 |
2013年 | 113篇 |
2012年 | 111篇 |
2011年 | 124篇 |
2010年 | 110篇 |
2009年 | 92篇 |
2008年 | 104篇 |
2007年 | 84篇 |
2006年 | 92篇 |
2005年 | 58篇 |
2004年 | 55篇 |
2003年 | 52篇 |
2002年 | 48篇 |
2001年 | 33篇 |
2000年 | 36篇 |
1999年 | 45篇 |
1998年 | 124篇 |
1997年 | 98篇 |
1996年 | 59篇 |
1995年 | 45篇 |
1994年 | 15篇 |
1993年 | 41篇 |
1992年 | 15篇 |
1991年 | 9篇 |
1990年 | 8篇 |
1989年 | 13篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1976年 | 7篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1971年 | 1篇 |
1949年 | 1篇 |
排序方式: 共有2159条查询结果,搜索用时 328 毫秒
41.
Pedro Luis Mateo Navarro Gregorio Martínez Pérez Diego Sevilla Ruiz 《International journal of human-computer interaction》2014,30(12):946-964
This article describes a novel approach to model the quality of experience (QoE) of users in mobile environments. The context-aware and ratings interaction model (CARIM) addresses the open questions of how to quantify user experiences from the analysis of interaction in mobile scenarios, and how to compare different QoE records to each other. A set of parameters are used to dynamically describe the interaction between the user and the system, the context in which it is performed and the perceived quality of users. CARIM structures these parameters into a uniform representation, supporting the dynamic analysis of interaction to determine QoE of users and enabling the comparison between different interaction records. Its run-time nature allows applications to make context- and QoE-based decisions in real time to adapt themselves, and thus provide a better experience to users. As a result, CARIM provides unified criteria for the inference and analysis of QoE in mobile scenarios. Its design and implementation can be integrated (and easily extended if needed) into many different development environments. An experiment with real users comparing two different interaction designs and validating user behavior hypotheses proved the effectiveness of applying CARIM for the assessment of QoE in mobile applications. 相似文献
42.
The influence of the addition of 1–10 vol.% of hydrogen or carbon dioxide to the feed during the partial oxidation of methane was studied over a NiO/γ-Al2O3 catalyst. The addition of H2 decreases the conversion and syngas selectivity. This decrease of performance seems to be related to a higher reduction of the catalyst due to the H2 co-feeding. The addition of CO2 also appears unfavorable to the production of hydrogen but increases the CO yield. A combination of the dry reforming and the reverse water gas shift reactions is suggested to explain the observed modifications in the product yields. 相似文献
43.
M. Victoria Ruiz‐Mndez lvaro E. Ramos‐Hinojosa 《European Journal of Lipid Science and Technology》2003,105(7):346-350
Two‐phase decanter olive pomace (TPOP) is the by‐product of a centrifugation system, used to produce olive oil, that separates olive oil and moist pomace. The water content in these olive pomaces is about 70%, while it was 45‐50% in the olive pomace stemming from three‐phase systems (oil, water, and pomace) and 30% in the old press system. The aim of this work is focused on quantification and changes undergone during olive pomace storage in ponds of esters of fatty acids with short‐chain linear alcohols, which can be considered as a refining loss. The results indicate that oil deterioration increases very rapidly, in particular when oil is extracted from the TPOP surface. Special attention should be paid to the storage of TPOP, establishing a maximum of 2 months in all cases. 相似文献
44.
ABSTRACT Many designers and User Interface (UI) educators discuss principles to be followed when designing the functional aspects of a UI. However, many UI principles have been proposed, scattered in scientific papers and teaching books. Some principles are different, and many are somehow similar or overlapping with others. This makes it very difficult to comprehend where to pay attention to when designing a UI. In this paper, we perform a systematic literature review to first identify the most relevant authors in the domain of functional UI design principles. Focusing on the three most cited works of these authors, we extracted 257 principles. We next analyzed all these principles, unified their variants, and, considering their scientific influence, finally derived a shorter and core selection of 36 principles. This core selection provides educators and UI designers with a clear path to teach, evaluate, learn and improve the UI functional design. 相似文献
45.
Tellez Eric S. Ruiz Guillermo Chavez Edgar Graff Mario 《Pattern Analysis & Applications》2021,24(2):763-777
Pattern Analysis and Applications - Nearest neighbor search is a powerful abstraction for data access; however, data indexing is troublesome even for approximate indexes. For intrinsically... 相似文献
46.
M. Lucena A. L. Martínez-Carrillo J. M. Fuertes F. Carrascosa A. Ruiz 《Multimedia Tools and Applications》2016,75(7):3677-3691
We present a decision support system to help archaeologists in classifying wheel-made pottery pieces by its profile. A novel shape characterization method, using Mathematical Morphology, is introduced for this purpose. Each profile is represented as a vector, obtained by sampling the so called morphological curves (erosion, dilation, opening and closing), and Euclidean Distance is used as a similarity measure. We show results of our method applied to a profile database of Iberian Pottery from the upper valley of Guadalquivir River (Spain). 相似文献
47.
Jialing Liu Yadav V. Sehgal H. Olson J.M. Haifeng Liu Elia N. 《Automatic Control, IEEE Transactions on》2008,53(8):1817-1825
In this paper, we study the phase transition behavior emerging from the interactions among multiple agents in the presence of noise. We propose a simple discrete-time model in which a group of non-mobile agents form either a fixed connected graph or a random graph process, and each agent, taking bipolar value either +1 or -1, updates its value according to its previous value and the noisy measurements of the values of the agents connected to it. We present proofs for the occurrence of the following phase transition behavior: At a noise level higher than some threshold, the system generates symmetric behavior (vapor or melt of magnetization) or disagreement; whereas at a noise level lower than the threshold, the system exhibits spontaneous symmetry breaking (solid or magnetization) or consensus. The threshold is found analytically. The phase transition occurs for any dimension. Finally, we demonstrate the phase transition behavior and all analytic results using simulations. This result may be found useful in the study of the collective behavior of complex systems under communication constraints. 相似文献
48.
In this work, a review and comprehensive evaluation of heuristics and metaheuristics for the m-machine flowshop scheduling problem with the objective of minimising total tardiness is presented. Published reviews about this objective usually deal with a single machine or parallel machines and no recent methods are compared. Moreover, the existing reviews do not use the same benchmark of instances and the results are difficult to reproduce and generalise. We have implemented a total of 40 different heuristics and metaheuristics and we have analysed their performance under the same benchmark of instances in order to make a global and fair comparison. In this comparison, we study from the classical priority rules to the most recent tabu search, simulated annealing and genetic algorithms. In the evaluations we use the experimental design approach and careful statistical analyses to validate the effectiveness of the different methods tested. The results allow us to clearly identify the state-of-the-art methods. 相似文献
49.
We develop a novel approach for computing the circle Hough transform entirely on graphics hardware (GPU). A primary role is assigned to vertex processors and the rasterizer, overshadowing the traditional foreground of pixel processors and enhancing parallel processing. Resources like the vertex cache or blending units are studied too, with our set of optimizations leading to extraordinary peak gain factors exceeding 358x over a typical CPU execution. Software optimizations, like the use of precomputed tables or gradient information and hardware improvements, like hyperthreading and multicores are explored on CPUs as well. Overall, the GPU exhibits better scalability and much greater parallel performance to become a solid alternative for computing the classical circle Hough transform versus those optimal methods run on emerging multicore architectures. 相似文献
50.
Geographic Routing(GR)algorithms require nodes to periodically transmit HELLO messages to allow neigh- bors to know their positions(beaconing mechanism).Beacon-less routing algorithms have recently been proposed to reduce the control overheads due to these messages.However,existing beacon-less algorithms have not considered realistic physical layers.Therefore,those algorithms cannot work properly in realistic scenarios.In this paper we present a new beacon- less routing protocol called BOSS.Its design is based on the conclusions of our open-field experiments using Tmote-sky sensors.BOSS is adapted to error-prone networks and incorporates a new mechanism to reduce collisions and duplicate messages produced during the selection of the next forwarder node.We compare BOSS with Beacon-Less Routing(BLR) and Contention-Based Forwarding(CBF)algorithms through extensive simulations.The results show that our scheme is able to achieve almost perfect packet delivery ratio(like BLR)while having a low bandwidth consumption(even lower than CBF).Additionally,we carried out an empirical evaluation in a real testbed that shows the correctness of our simulation results. 相似文献