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61.
Towards the development of a virtual environment-based training system for mechanical assembly operations 总被引:2,自引:1,他引:1
John E. Brough Maxim Schwartz Satyandra K. Gupta Davinder K. Anand Robert Kavetsky Ralph Pettersen 《Virtual Reality》2007,11(4):189-206
In this paper, we discuss the development of Virtual Training Studio (VTS), a virtual environment-based training system that
allows training supervisors to create training instructions and allows trainees to learn assembly operations in a virtual
environment. Our system is mainly focused on the cognitive side of training so that trainees can learn to recognize parts,
remember assembly sequences, and correctly orient the parts during assembly operations. Our system enables users to train
using the following three training modes: (1) Interactive Simulation, (2) 3D Animation, and (3) Video. Implementing these
training modes required us to develop several new system features. This paper presents an overview of the VTS system and describes
a few main features of the system. We also report user test results that show how people train using our system. The user
test results indicate that the system is able to support a wide variety of training preferences and works well to support
training for assembly operations.
相似文献
Satyandra K. GuptaEmail: |
62.
Summary An overview ofvariational inequality andvariational equality formulations for frictionless contact and frictional contact problems is provided. The aim is to discuss the state-of-the-art
in these two formulations and clearly point out their advantages and disadvantages in terms of mathematical completeness and
practicality. Various terms required to describe the contact configuration are defined.Unilateral contact law and classical Coulomb’s friction law are given.Elastostatic frictional contact boundary value problem is defined. General two-dimensional frictionless and frictional contact formulations for elastostatic
problems are investigated. An example problem of a two bar truss-rigid wall frictionless contact system is formulated as an
optimization problem based on the variational inequality approach. The problem is solved in a closed form using the Karush-Kuhn-Tucker
(KKT) optimality conditions. The example problem is also formulated as a frictional contact system. It is solved in the closed
form using a new two-phase analytical procedure. The procedure avoids use of the incremental/iterative techniques and user
defined parameters required in a typical implementation based on the variational equality formulation. Numerical solutions
for the frictionless and frictional contact problems are compared with the results obtained by using a general-purpose finite
element program ANSYS (that uses variational equality formulation). ANSYS results match reasonably well with the solutions
of KKT optimality conditions for the frictionless contact problem and the two-phase procedure for the frictional contact problem.
The validity of the analytical formulation for frictional contact problems (with one contacting node) is verified. Thevariational equality formulation for frictionless and frictional, contact problems is also studied in detail. The incremental/iterative Newton-Raphson
scheme incorporating the penalty approach is utilized. Studies are conducted to provide insights for the numerical solution
techniques. Based on the present study it is concluded that alternate formulations and computational procedures need to be
developed for analysis of frictional contact problems. 相似文献
63.
64.
Today flotation column has become an acceptable means of froth flotation for a fairly broad range of applications, in particular the cleaning of sulfides. Even after having been used for several years in mineral processing plants, the full potential of the flotation column process is still not fully exploited. There is no prediction of process performance for the complete use of available control capabilities. The on-line estimation of grade usually requires a significant amount of work in maintenance and calibration of on-stream analyzers, in order to maintain good accuracy and high availability. These difficulties and the high cost of investment and maintenance of these devices have encouraged the approach of prediction of metal grade and recovery. In this paper, a new approach has been proposed for metallurgical performance prediction in flotation columns using Artificial Neural Network (ANN). Despite of the wide range of applications and flexibility of NNs, there is still no general framework or procedure through which the appropriate network for a specific task can be designed. Design and structural optimization of NNs is still strongly dependent upon the designer’s experience. To mitigate this problem, a new method for the auto-design of NNs was used, based on Genetic Algorithm (GA). The new proposed method was evaluated by a case study in pilot plant flotation column at Sarcheshmeh copper plant. The chemical reagents dosage, froth height, air, wash water flow rates, gas holdup, Cu grade in the rougher feed, flotation column feed, column tail and final concentrate streams were used to the simulation by GANN. In this work, multi-layer NNs with Back Propagation (BP) algorithm with 8-17-10-2 and 8-13-6-2 arrangements have been applied to predict the Cu and Mo grades and recoveries, respectively. The correlation coefficient (R) values for the testing sets for Cu and Mo grades were 0.93, 0.94 and for their recoveries were 0.93, 0.92, respectively. The results discussed in this paper indicate that the proposed model can be used to predict the Cu and Mo grades and recoveries with a reasonable error. 相似文献
65.
Operation, system architectures, and physical Layer design considerations of distributed MAC protocols for UWB 总被引:2,自引:0,他引:2
Impulse-based ultra wideband (I-UWB) is an attractive radio technology for large ad hoc and sensor networks due to its robustness to harmful multipath effects, sub-centimeter ranging ability, simple hardware, and low radiated power. To scale to large sizes, networks often implement distributed medium access control (MAC) protocols. However, most MAC protocols for I-UWB are centralized, and they target small wireless personal area networks and cellular networks. We propose three distributed MAC protocols suitable for I-UWB. Two multichannel protocols, called multichannel pulse sense multiple access (M-PSMA) and multichannel ALOHA achieve high aggregate throughput. A busy-signal protocol, called busy-signal multiple access (BSMA), reduces the energy wasted from re-transmitted packets. This paper describes the three protocols in terms of the protocol's operation, the supporting system architecture, and the I-UWB physical layer. Physical layer simulations confirm the feasibility of implementing the proposed systems and also provide parameters for network simulations. Network simulations show that the throughput of M-PSMA exceeds that of a centralized time-division multiple-access protocol and that the energy efficiency of BSMA far surpasses that of other distributed protocols. 相似文献
66.
Young‐Sam Cho Seyoung Im 《International journal for numerical methods in engineering》2006,65(4):494-516
Two‐dimensional variable‐node elements compatible with quadratic interpolation are developed using the moving least‐square (MLS) approximation. The mapping from the parental domain to the physical element domain is implicitly obtained from MLS approximation, with the shape functions and their derivatives calculated and saved only at the numerical integration points. It is shown that the present MLS‐based variable‐node elements meet the patch test if a sufficiently large number of integration points are employed for numerical integration. The cantilever problem with non‐matching meshes is chosen to check the feasibility of the present MLS‐based variable‐node elements, and the result is compared with that from the lower‐order case compatible with linear interpolation. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
67.
Wook Hyun Kwon Jin Won Kang Young Sam Lee Young Soo Moon 《Journal of Process Control》2003,13(6):1080
In this paper, a simple receding horizon (or model predictive) control for state delayed systems is presented and its solution is given in a closed form by a reduction method. While the control for a time-delay system is usually complex, the proposed controller is simple to construct and therefore can be simply implemented in real applications. To check the closed-loop stability of the proposed controller, a sufficient condition is provided by linear matrix inequalities. In addition, a numerical algorithm is presented for computing the eigenvalues of systems with distributed time delays, which can be used as a necessary and sufficient condition to check closed-loop stability. It is shown by simulation that this simple control can be a stabilizing control for time-delay systems. 相似文献
68.
Several commercial applications, such as online comparison shopping and process automation, require integrating information that is scattered across multiple websites or XML documents. Much research has been devoted to this problem, resulting in several research prototypes and commercial implementations. Such systems rely on wrappers that provide relational or other structured interfaces to websites. Traditionally, wrappers have been constructed by hand on a per-website basis, constraining the scalability of the system. We introduce a website structure inference mechanism called compact skeletons that is a step in the direction of automated wrapper generation. Compact skeletons provide a transformation from websites or other hierarchical data, such as XML documents, to relational tables. We study several classes of compact skeletons and provide polynomial-time algorithms and heuristics for automated construction of compact skeletons from websites. Experimental results show that our heuristics work well in practice. We also argue that compact skeletons are a natural extension of commercially deployed techniques for wrapper construction. 相似文献
69.
Modular Reconfigurable Robots in Space Applications 总被引:6,自引:0,他引:6
Mark Yim Kimon Roufas David Duff Ying Zhang Craig Eldershaw Sam Homans 《Autonomous Robots》2003,14(2-3):225-237
Robots used for tasks in space have strict requirements. Modular reconfigurable robots have a variety of attributes that are well suited to these conditions, including: serving as many different tools at once (saving weight), packing into compressed forms (saving space) and having high levels of redundancy (increasing robustness). In addition, self-reconfigurable systems can self-repair and adapt to changing or unanticipated conditions. This paper will describe such a self-reconfigurable modular robot: PolyBot. PolyBot has significant potential in the space manipulation and surface mobility class of applications for space. 相似文献
70.