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21.
Autonomy for Mars Rovers: Past, Present, and Future 总被引:1,自引:0,他引:1
The vehicles used to explore the Martian surface require a high degree of autonomy to navigate challenging and unknown terrain, investigate targets, and detect scientific events. Increased autonomy will be critical to the success of future missions. 相似文献
22.
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24.
Tunable Thermal‐Sensitive Polymer–Graphene Oxide Composite for Efficient Capture and Release of Viable Circulating Tumor Cells 下载免费PDF全文
25.
Max I. Kanovich Mitsuhiro Okada Andre Scedrov 《Electronic Notes in Theoretical Computer Science》1998,16(1):42-59
Abstract
Real-time finite-state systems may be specified in linear logic by means of linear implications between conjunctions of fixed finite length. In this setting, where time is treated as a dense linear ordering, safety properties may be expressed as certain provability problems. These provability problems are shown to be in pspace. They are solvable, with some guidance, by finite proof search in concurrent logic programming environments based on linear logic and acting as sort of model-checkers. One advantage of our approach is that either it provides unsafe runs or it actually establishes safety. 相似文献26.
The Gaussian scale-space paradigm and the multiscale local jet 总被引:3,自引:3,他引:0
Luc Florack Bart Ter Haar Romeny Max Viergever Jan Koenderink 《International Journal of Computer Vision》1996,18(1):61-75
A representation of local image structure is proposed which takes into account both the image's spatial structure at a given location, as well as its deep structure, that is, its local behaviour as a function of scale or resolution (scale-space). This is of interest for several low-level image tasks. The proposed basis of scale-space, for example, enables a precise local study of interactions of neighbouring image intensities in the course of the blurring process. It also provides an extrapolation scheme for local image data, obtained at a given spatial location and resolution, to a finite scale-space neighbourhood. This is especially useful for the determination of sampling rates and for interpolation algorithms in a multilocal context. Another, particularly straightforward application is image enhancement or deblurring, which is an instance of data extrapolation in the high-resolution direction.A potentially interesting feature of the proposed local image parametrisation is that it captures a trade-off between spatial and scale extrapolations from a given interior point that do not exceed a given tolerance. This (rade-off suggests the possibility of a fairly coarse scale sampling at the expense of a dense spatial sampling large relative spatial overlap of scale-space kernels).The central concept developed in this paper is an equivalence class called the multiscale local jet, which is a hierarchical, local characterisation of the image in a full scale-space neighbourhood. For this local jet, a basis of fundamental polynomials is constructed that captures the scale-space paradigm at the local level up to any given order. 相似文献
27.
Sliding Mode Control with Adaptive Fuzzy Dead-Zone Compensation of an Electro-hydraulic Servo-System 总被引:2,自引:0,他引:2
Wallace M. Bessa Max S. Dutra Edwin Kreuzer 《Journal of Intelligent and Robotic Systems》2010,58(1):3-16
Electro-hydraulic servo-systems are widely employed in industrial applications such as robotic manipulators, active suspensions,
precision machine tools and aerospace systems. They provide many advantages over electric motors, including high force to
weight ratio, fast response time and compact size. However, precise control of electro-hydraulic systems, due to their inherent
nonlinear characteristics, cannot be easily obtained with conventional linear controllers. Most flow control valves can also
exhibit some hard nonlinearities such as dead-zone due to valve spool overlap. This work describes the development of an adaptive
fuzzy sliding mode controller for an electro-hydraulic system with unknown dead-zone. The boundedness and convergence properties
of the closed-loop signals are proven using Lyapunov stability theory and Barbalat’s lemma. Numerical results are presented
in order to demonstrate the control system performance. 相似文献
28.
Sliding mode control is a very attractive control scheme because of its robustness against both structured and unstructured uncertainties as well as external disturbances. In this way, it has been widely employed for the dynamic positioning of remotely operated underwater vehicles. Nevertheless, in such situations the discontinuities in the control law must be smoothed out to avoid the undesirable chattering effects. The adoption of properly designed boundary layers has proven effective in completely eliminating chattering, however, leading to an inferior tracking performance. This work describes the development of a dynamic positioning system for remotely operated underwater vehicles. The adopted approach is primarily based on the sliding mode control strategy and enhanced by an adaptive fuzzy algorithm for uncertainty/disturbance compensation. Using the Lyapunov stability theory and Barbalat’s lemma, the boundedness and convergence properties of the closed-loop signals are analytically proven. The performance of the proposed control scheme is also evaluated by means of numerical simulations. 相似文献
29.
Andreas Birk Burkhard Wiggerich Heiko Bülow Max Pfingsthorn Sören Schwertfeger 《Journal of Intelligent and Robotic Systems》2011,64(1):57-76
Several missions with an Unmanned Aerial Vehicle (UAV) in different realistic safety, security, and rescue field tests are
presented. First, results from two safety and security missions at the 2009 European Land Robot Trials (ELROB) are presented.
A UAV in form of an Airrobot AR100-B is used in a reconnaissance and in a camp security scenario. The UAV is capable of autonomous
waypoint navigation using onboard GPS processing. A digital video stream from the vehicle is used to create photo maps—also
known as mosaicking—in real time at the operator station. This mapping is done using an enhanced version of Fourier Mellin
based registration, which turns out to be very fast and robust. Furthermore, results from a rescue oriented scenario at the
2010 Response Robot Evaluation Exercises (RREE) at Disaster City, Texas are presented. The registration for the aerial mosaicking
is supplemented by an uncertainty metric and embedded into Simultaneous Localization and Mapping (SLAM), which further enhances
the photo maps as main mission deliveries. 相似文献
30.
Stefan Klein Josien P. W. Pluim Marius Staring Max A. Viergever 《International Journal of Computer Vision》2009,81(3):227-239
We present a stochastic gradient descent optimisation method for image registration with adaptive step size prediction. The
method is based on the theoretical work by Plakhov and Cruz (J. Math. Sci. 120(1):964–973, 2004). Our main methodological contribution is the derivation of an image-driven mechanism to select proper values for the most
important free parameters of the method. The selection mechanism employs general characteristics of the cost functions that
commonly occur in intensity-based image registration. Also, the theoretical convergence conditions of the optimisation method
are taken into account. The proposed adaptive stochastic gradient descent (ASGD) method is compared to a standard, non-adaptive
Robbins-Monro (RM) algorithm. Both ASGD and RM employ a stochastic subsampling technique to accelerate the optimisation process.
Registration experiments were performed on 3D CT and MR data of the head, lungs, and prostate, using various similarity measures
and transformation models. The results indicate that ASGD is robust to these variations in the registration framework and
is less sensitive to the settings of the user-defined parameters than RM. The main disadvantage of RM is the need for a predetermined
step size function. The ASGD method provides a solution for that issue. 相似文献