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31.
工业过程随机稳态优化控制算法的鲁棒性分析 总被引:1,自引:0,他引:1
本文给出了一种随机稳态优化算法的灵敏度分析,讨论算法解对参数变化的关系。这些参数代表系统结构参数或噪声向量的某些数字特征. 相似文献
32.
In this paper,a sequential algorithm computing the aww vertex pair distance matrix D and the path matrix Pis given.On a PRAM EREW model with p,1≤p≤n^2,processors,a parallel version of the sequential algorithm is shown.This method can also be used to get a parallel algorithm to compute transitive closure array A^* of an undirected graph.The time complexity of the parallel algorithm is O(n^3/p).If D,P and A^* are known,it is shown that the problems to find all connected components,to compute the diameter of an undirected graph,to determine the center of a directed graph and to search for a directed cycle with the minimum(maximum)length in a directed graph can all be solved in O(n^2/p logp)time. 相似文献
33.
A Linear Cross-Coupled Control System for High-Speed Machining 总被引:4,自引:0,他引:4
Q. Zhong Y. Shi J. Mo S. Huang 《The International Journal of Advanced Manufacturing Technology》2002,19(8):558-563
We present a linear cross-coupled controller to improve highspeed contouring accuracy independently of tracking accuracy in
a biaxial machine tool feed drive servomechanism. Unlike conventional cross-coupled controllers, the cross-coupled controller
presented here is a linear system, so it is very easy to perform the stability and steady-state error analysis, and to optimise
the controller parameters. The proposed controller is evaluated experimentally on a CNC LOM machine and compared to an uncoupled
controller and a conventional cross-coupled controller. Controller performance is evaluated for a circular contour at a feedrate
of 30 m min _1 . The experimental results show that the proposed controller can greatly reduce the contour error at large feedrates. The
linear cross-coupled controller is simple to implement and is practical. 相似文献
34.
I. Belda X. Llorà E. Giralt 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2006,10(4):295-304
One of the goals of computational chemistry is the automated de novo design of bioactive molecules. Despite significant progress
in computational approaches to ligand design and efficient evaluation of binding energy, novel procedures for ligand design
are required. Evolutionary computation provides a new approach to this design issue. This paper presents an automated methodology
for computer-aided peptide design based on evolutionary algorithms. It provides an automatic tool for peptide de novo design,
based on protein surface patches defined by user. Regarding the restrictive constrains of this problem a special emphasis has been made on the design of the
evolutionary algorithms implemented. 相似文献
35.
36.
37.
Given a graph G=(V,E) and a positive integer D , we consider the problem of finding a minimum number of new edges E' such that the augmented graph G'=(V,E\cup E') is biconnected and has diameter no greater than D. In this note we show that this problem is NP-hard for all fixed D , by employing a reduction from the DOMINATING SET problem. We prove that the problem remains NP-hard even for forests and
trees, but in this case we present approximation algorithms with worst-case bounds 3 (for even D ) and 6 (for odd D ). A closely related problem of finding a minimum number of edges such that the augmented graph has diameter no greater than
D has been shown to be NP-hard by Schoone et al. [21] when D=3 , and by Li et al. [17] when D=2.
Received April 19, 1999; revised June 5, 2001. 相似文献
38.
Timothy Thomasma Kurt Hilbrecht 《International Journal of Flexible Manufacturing Systems》1991,3(3-4):231-250
Good methods are needed to specify, test, and debug material-handling control logic. This article surveys a number of representative methods for defining and describing control algorithms for programmable material-handling equipment used in flexible manufacturing systems. The methods are evaluated with regard to their suitability for communication between people and as bases for interfaces to automatic program generators. It is concluded that no single method is entirely satisfactory. Three methods (position diagrams, function block diagrams, and operation networks) have potential to be combined into an effective hybrid approach that minimizes the need for the user to switch between various conceptual models. 相似文献
39.
WANG Jianwei WEI Xiaopeng LI Rui 《机械工程学报(英文版)》2008,21(1):111-115
Due to the combinatorial nature of cell formation problem and the characteristics of multi-objective and multi-constrain, a novel method of evolutionary algorithm with preference is proposed. The analytic hierarchy process (AHP) is adopted to determine scientifically the weights of the sub-objective functions. The satisfaction of constraints is considered as a new objective, the ratio of the population which doesn't satisfy all constraints is assigned as the weight of new objective. In addition, the self-adaptation of weights is applied in order to converge more easily towards the feasible domain. Therefore, both features multi-criteria and constrains are dealt with simultaneously. Finally, an example is selected from the literature to evaluate the performance of the proposed approach. The results validate the effectiveness of the proposed method in designing the manufacturing cells. 相似文献
40.
One of the problems encountered by automatic feeding devices, such as vibratory bowl feeders, in robotic assembly systems is nesting which leads to inseparability of parts and jamming. In this paper, we describe a design evaluation procedure to determine whether a part is prone to nesting and to quantify the degree of nesting. The proposed methodology reduces the 3-D protrusion-hole polyhedral containment problem of nesting to a 2-D polygon containment problem by employing a loop-based feature recognition scheme. Subsequently, the 3-D containment configuration is reconstructed from that of the 2-D by using a strategy calleddrop, pull and push. In this context, we introduce the notion of axis as a characteristic direction of a feature that facilitates the analysis of generalized 3-D polyhedral containment. The algorithms are applicable to generic B-Rep CAD data, and their time and space complexities are polynomial. 相似文献