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排序方式: 共有2223条查询结果,搜索用时 15 毫秒
31.
Kim Kihyeun Son Myungwoo Pak Yusin Chee Sang-Soo Auxilia Francis Malar Lee Byung-Kee Lee Sungeun Kang Sun Kil Lee Chaedeok Lee Jeong Soo Kim Ki Kang Jang Yun Hee Lee Byoung Hun Jung Gun-Young Ham Moon-Ho 《Nano Research》2018,11(7):3957-3957
Nano Research - The order of the authors in the original version of this article was unfortunately incorrect on the first page and the first page of the ESM. Instead of Myungwoo Son1, Yusin Pak1,... 相似文献
32.
Thermal actuated sliders are being widely used in today’s hard disk drive industry for its advantages of easier control of flying height (FH) and less risk of contacts with the disk. This article uses a coupled-field analysis method, which includes an air bearing model, a heat transfer model and a thermal-structural finite element model to investigate the FH changes of thermal actuated sliders at various environmental conditions. The mechanism of water vapour’s contribution to air bearing pressure loss is explained and a new humidity model is proposed to calculate this pressure loss. The temperature effects are also considered in the simulation models. It is observed that the environmental temperature and humidity have significant effects on slider’s FH changes, but their effects on the thermal protrusion height are limited. A humidity sensitivity study is also made and the results are discussed. It is found that the slider with thermal protrusion on its trailing pad will be more sensitive to the humidity. Besides air bearing stiffness, some other factors such as peak pressure, protrusion shape and air bearing surface (ABS) design will also contribute to the slider’s humidity sensitivity. 相似文献
33.
This paper presents a backstepping control method using radial‐basis‐function neural network (RBFNN) for improving trajectory tracking performance of a robotic helicopter. Many well‐known nonlinear controllers for robotic helicopters have been constructed based on the approximate dynamic model in which the coupling effect is neglected; their qualitative behavior must be further analyzed to ensure that the unmodeled dynamics do not destroy the stability of the closed‐loop system. In order to improve the controller design process, the proposed controller is developed based on the complete dynamic model of robotic helicopters by using an RBFNN function approximation to the neglected dynamic uncertainties, and then proving that all the trajectory tracking error variables are globally ultimately bounded and converge to a neighborhood of the origin. The merits of the proposal controller are exemplified by four numerical simulations, showing that the proposed controller outperforms a well‐known controller in (J. Robust Nonlinear Control 2004; 14 (12):1035–1059). Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
34.
35.
Kok Yew Ng Chee Pin Tan Rini Akmeliawati Christopher Edwards 《Asian journal of control》2010,12(5):656-660
This paper investigates and presents conditions that guarantee disturbance decoupled fault reconstruction using sliding mode observers, which are less stringent than those of previous work, and show that disturbance reconstruction is not necessary. An aircraft model validates the ideas proposed in this paper. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society 相似文献
36.
In this paper, we first introduce the use of an interactive hidden Markov model (IHMM) for modeling and analyzing default
data in a sector. Under the IHMM, transitions of the hidden risk states of the sector depend on the observed number of bonds
in the sector that default in the current time period. This incorporates the feedback effect of the number of defaults on
the transitions of the hidden risk states. This feature seems to be more realistic and does not enjoy by the traditional HMMs.
We then develop a “dynamic” version of the binomial expansion technique (BET) modulated by the IHMM for modeling the occurrence
of defaults of bonds issued by firms in the same sector. Under the BET modulated by the IHMM, the number of bonds defaulting
in each time period follows a Markov-modulated binomial distribution with the probability of defaulting of each bond depending
on the states of the IHMM, which represent the hidden risk states of the sector. Efficient method will be presented for estimating
the model parameters in the BET modulated by the IHMM. We shall compare the hidden risk state process extracted from the IHMM-modulated
BET with that extracted from the BET modulated by HMM in order to illustrate the significance of the feedback effect using
real data. We shall also present the estimation results for the BET modulated by the IHMM and compare them with those for
the BET modulated by the HMM. 相似文献
37.
A simple robust control for global asymptotic position stabilization of underactuated surface vessels
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Global asymptotic stabilization of underactuated surface vessels is generally achieved only by designing complicated controllers. This paper proposes a very simple control law that globally asymptotically stabilizes the position of underactuated surface vessel to a desired constant location and its velocities to zero. The proposed controller is independent of velocity signals and is robust to model parameters. It neither includes an observer nor an adaptive/sliding‐mode law. Controller development and stability analysis rely on a novel Lyapunov function and LaSalle's theorem. Furthermore, by extending the proposed control strategy, a saturated control law is also obtained ensuring the semiglobal asymptotic stability of position error system. Effectiveness of the proposed control schemes is demonstrated by simulation examples. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
38.
Comparison of image reconstruction by using near‐field and far‐field data for an imperfect conductor
Image reconstruction by using near‐field and far‐field data for an imperfectly conducting cylinder is investigated. A conducting cylinder of unknown shape and conductivity scatters the incident wave in free space and the scattered near and far fields are measured. By using measured fields, the imaging problem is reformulated into an optimization problem and solved by the genetic algorithm. Numerical results show that the convergence speed and final reconstructed results by using near‐field data are better than those obtained by using far‐field data. This work provides both comparative and quantitative information. © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 69–73, 2001. 相似文献
39.
This paper proposes a probabilistic variant of the SOM-kMER (Self Organising Map-kernel-based Maximum Entropy learning Rule)
model for data classification. The classifier, known as pSOM-kMER (probabilistic SOM-kMER), is able to operate in a probabilistic
environment and to implement the principles of statistical decision theory in undertaking classification problems. A distinctive
feature of pSOM-kMER is its ability in revealing the underlying structure of data. In addition, the Receptive Field (RF) regions
generated can be used for variable kernel and non-parametric density estimation. Empirical evaluation using benchmark datasets
shows that pSOM-kMER is able to achieve good performance as compared with those from a number of machine learning systems.
The applicability of the proposed model as a useful data classifier is also demonstrated with a real-world medical data classification
problem. 相似文献
40.
Joc Cing Tay Cheun Hou Tng Chee Siong Chan 《Genetic Programming and Evolvable Machines》2008,9(1):5-37
The game of tag is frequently used in the study of pursuit and evasion strategies that are discovered through competitive
coevolution. The aim of coevolution is to create an arms race where opposing populations cyclically evolve in incremental
improvements, driving the system towards better strategies. A coevolutionary simulation of the game of tag involving two populations
of agents; pursuers and evaders, is developed to investigate the effects of a boundary and two obstacles. The evolution of
strategies through Chemical Genetic Programming optimizes the mapping of genotypic strings to phenotypic trees. Four experiments
were conducted, distinguished by speed differentials and environmental conditions. Designing experiments to evaluate the efficacy
of emergent strategies often reveal necessary steps needed for coevolutionary progress. The experiments that excluded obstacles
and boundaries provided design pointers to ensure coevolutionary progress as well as a deeper understanding of strategies
that emerged when obstacles and boundaries were added. In the latter, we found that an awareness of the environment and the
pursuer was not critical in an evader’s strategy to survive, instead heading to the edge of the boundary or behind an obstacle
in a bid to ‘throw-off or hide from the pursuer’ or simply turn in circles was often sufficient, thereby revealing possible
suboptimal strategies that were environment specific. We also observed that a condition for coevolutionary progress was that
the problem complexity must be surmountable by at least one population; that is, some pursuer must be able to tag an opponent.
Due to the use of amino-acid building blocks in our Chemical Genetic Program, our simulations were able to achieve significant
complexity in a short period of time.
相似文献
Joc Cing TayEmail: |