全文获取类型
收费全文 | 33812篇 |
免费 | 3491篇 |
国内免费 | 3048篇 |
学科分类
工业技术 | 40351篇 |
出版年
2024年 | 149篇 |
2023年 | 352篇 |
2022年 | 672篇 |
2021年 | 697篇 |
2020年 | 783篇 |
2019年 | 674篇 |
2018年 | 677篇 |
2017年 | 922篇 |
2016年 | 938篇 |
2015年 | 1125篇 |
2014年 | 1822篇 |
2013年 | 1882篇 |
2012年 | 2441篇 |
2011年 | 2835篇 |
2010年 | 2293篇 |
2009年 | 2483篇 |
2008年 | 2588篇 |
2007年 | 2981篇 |
2006年 | 2757篇 |
2005年 | 2291篇 |
2004年 | 1910篇 |
2003年 | 1571篇 |
2002年 | 1242篇 |
2001年 | 1073篇 |
2000年 | 856篇 |
1999年 | 544篇 |
1998年 | 371篇 |
1997年 | 329篇 |
1996年 | 217篇 |
1995年 | 177篇 |
1994年 | 113篇 |
1993年 | 118篇 |
1992年 | 96篇 |
1991年 | 86篇 |
1990年 | 43篇 |
1989年 | 70篇 |
1988年 | 33篇 |
1987年 | 18篇 |
1986年 | 12篇 |
1985年 | 10篇 |
1984年 | 7篇 |
1983年 | 12篇 |
1982年 | 17篇 |
1981年 | 11篇 |
1980年 | 12篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1975年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Xianpeng Wang Lixin Tang 《The International Journal of Advanced Manufacturing Technology》2008,36(5-6):431-441
This paper investigates the hot rolling production scheduling problem in the steel industry and proposes a new mixed integer
programming model for this problem based on the monolithic modeling strategy that integrates batching and scheduling. Using
this strategy, the new model can simultaneously schedule multiple turns and simultaneously determine the production timetable
of these turns in a global optimal view. A long-term tabu search heuristic using frequency-based memory is developed to obtain
near-optimal solutions for this problem. Three kinds of speed-up strategies are developed to accelerate the search procedure
of the proposed tabu search. A practical scheduling system combining the proposed mathematical model and the tabu search heuristic
has been developed and tested on instances collected from practical production data. The experimental results show that the
proposed mathematical model and the tabu search heuristic outperform both the current manual scheduling method and the traditional
serial method. 相似文献
62.
杜昱 《数字社区&智能家居》2006,(8):15-15,57
文章首先概述了当前大多数的搜索引擎的主要的弊端;然后着重介绍了智能检索系统的运行基本思路和售用算法,以及该算法在检索领域中运用的优点;最后指出,神经网络运用在检索领域,可解决网络管理中的诸多难题。 相似文献
63.
通过动态分析和现场测试对一喷气客机的发动机振动作出诊断,发现涡轮叶轮的变柔导致其极转动惯量显著下降,因而改变发动机的动态特性,使其临界转速接近飞机的巡航转速,产生不应有的振动和噪声。文章提出了具体改进方案,已为研制单位采用。 相似文献
64.
金属表面柴油机油沉积物的反射红外光谱法研究 总被引:1,自引:1,他引:0
利用镜反射红外光谱法研究了CC级柴油机油中添加剂对成漆板板面漆膜组成的影响:考察了成漆板漆膜组成与Cat.1H2活塞环台漆膜组成的相关性。试验结果对柴油机油的研制和应用有一定指导作用。 相似文献
65.
Intelligent scheduling with tabu search: An application to jobs with linear delay penalties and sequence-dependent setup costs and times 总被引:3,自引:0,他引:3
In this article we study thetabu search (TS) method in an application for solving an important class of scheduling problems. Tabu search is characterized by integrating artificial intelligence and optimization principles, with particular emphasis on exploiting flexible memory structures, to yield a highly effective solution procedure. We first discuss the problem of minimizing the sum of the setup costs and linear delay penalties when N jobs, arriving at time zero, are to be scheduled for sequential processing on a continuously available machine. A prototype TS method is developed for this problem using the common approach of exchanging the position of two jobs to transform one schedule into another. A more powerful method is then developed that employs insert moves in combination with swap moves to search the solution space. This method and the best parameters found for it during the preliminary experimentation with the prototype procedure are used to obtain solutions to a more complex problem that considers setup times in addition to setup costs. In this case, our procedure succeeded in finding optimal solutions to all problems for which these solutions are known and a better solution to a larger problem for which optimizing procedures exceeded a specified time limit (branch and bound) or reached a memory overflow (branch and bound/dynamic programming) before normal termination. These experiments confirm not only the effectiveness but also the robustness of the TS method, in terms of the solution quality obtained with a common set of parameter choices for two related but different problems. 相似文献
66.
Markovian and semi-Markovian random processes are used to analyze the problem of optimal search for signals in a multichannel
communication system with arbitrarily distributed random outputs. The search efficiency factor is found in explicit form based
on state space merging, and a mathematical programming problem is set up to find a numerical suboptimal solution.
__________
Translated from Kibernetika i Sistemnyi Analiz, No. 3, pp. 144–150, May–June 2007. 相似文献
67.
In this paper we present an efficient technique for piecewise cubic Bézier approximation of digitized curve. An adaptive breakpoint detection method divides a digital curve into a number of segments and each segment is approximated by a cubic Bézier curve so that the approximation error is minimized. Initial approximated Bézier control points for each of the segments are obtained by interpolation technique i.e. by the reverse recursion of De Castaljau's algorithm. Two methods, two-dimensional logarithmic search algorithm (TDLSA) and an evolutionary search algorithm (ESA), are introduced to find the best-fit Bézier control points from the approximate interpolated control points. ESA based refinement is proved to be better experimentally. Experimental results show that Bézier approximation of a digitized curve is much more accurate and uses less number of points compared to other approximation techniques. 相似文献
68.
The concept of combinatorial objects is formalized. It allows strict definition of a combinatorial optimization problem (COP).
An efficient metaheuristic method to solve COPs (H-method) is considered. It includes stochastic local search algorithms as
a built-in procedure. A parallel implementation of the H-method is set forth and analyzed. The results from a numerical experiment
and solution of some well-known COPs on personal computers and on the SKIT cluster supercomputer are presented.
The study was supported by INTAS (Project 06-1000017-8909).
__________
Translated from Kibernetika i Sistemnyi Analiz, No. 6, pp. 70–79, November–December 2007. 相似文献
69.
70.