全文获取类型
收费全文 | 21355篇 |
免费 | 2579篇 |
国内免费 | 1910篇 |
学科分类
工业技术 | 25844篇 |
出版年
2024年 | 135篇 |
2023年 | 335篇 |
2022年 | 540篇 |
2021年 | 638篇 |
2020年 | 677篇 |
2019年 | 626篇 |
2018年 | 567篇 |
2017年 | 797篇 |
2016年 | 954篇 |
2015年 | 1023篇 |
2014年 | 1449篇 |
2013年 | 1465篇 |
2012年 | 1759篇 |
2011年 | 1887篇 |
2010年 | 1353篇 |
2009年 | 1346篇 |
2008年 | 1260篇 |
2007年 | 1475篇 |
2006年 | 1217篇 |
2005年 | 1074篇 |
2004年 | 836篇 |
2003年 | 763篇 |
2002年 | 543篇 |
2001年 | 488篇 |
2000年 | 434篇 |
1999年 | 346篇 |
1998年 | 319篇 |
1997年 | 244篇 |
1996年 | 215篇 |
1995年 | 199篇 |
1994年 | 175篇 |
1993年 | 168篇 |
1992年 | 109篇 |
1991年 | 79篇 |
1990年 | 72篇 |
1989年 | 53篇 |
1988年 | 43篇 |
1987年 | 31篇 |
1986年 | 23篇 |
1985年 | 31篇 |
1984年 | 18篇 |
1983年 | 13篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1959年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Redundancy allocation problem (RAP) is one of the best-developed problems in reliability engineering studies. This problem follows to optimize the reliability of a system containing s sub-systems under different constraints, including cost, weight, and volume restrictions using redundant components for each sub-system. Various solving methodologies have been used to optimize this problem, including exact, heuristic, and meta-heuristic algorithms. In this paper, an efficient multi-objective meta-heuristic algorithm based on simulated annealing (SA) is developed to solve multi-objective RAP (MORAP). This algorithm is knowledge-based archive multi-objective simulated annealing (KBAMOSA). KBAMOSA applies a memory matrix to reinforce the neighborhood structure to achieve better quality solutions. The results analysis and comparisons demonstrate the performance of the proposed algorithm for solving MORAP. 相似文献
2.
Load testing of applications is an important and costly activity for software provider companies. Classical solutions are very difficult to set up statically, and their cost is prohibitive in terms of both human and hardware resources. Virtualized cloud computing platforms provide new opportunities for stressing an application's scalability, by providing a large range of flexible and less expensive (pay‐per‐use model) computation units. On the basis of these advantages, load testing solutions could be provided on demand in the cloud. This paper describes a Benchmark‐as‐a‐Service solution that automatically scales the load injection platform and facilitates its setup according to load profiles. Our approach is based on: (i) virtualization of the benchmarking platform to create self‐scaling injectors; (ii) online calibration to characterize the injector's capacity and impact on the benched application; and (iii) a provisioning solution to appropriately scale the load injection platform ahead of time. We also report experiments on a benchmark illustrating the benefits of this system in terms of cost and resource reductions. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
3.
讨论了在VMI管理思想下对具有随机需求特性的多客户库存分配问题 ,重点论述了有效近似算法的设计过程 ,最后基于一组模拟数据给出了一个算例。 相似文献
4.
卫星电视上行站信号自动监测系统 总被引:1,自引:0,他引:1
鄂志东 《信息安全与通信保密》2006,(3):84-85
每个卫星电视上行站都必须对卫星转发器上的电视信号进行监测,才能及时发现卫星电视上行信号的异常变化,准确处理异常突发干扰。为实现自动、连续、实时监测,就需要建立卫星电视上行站射频信号自动监测系统。文章详细介绍了一个自动监测系统的设计及实现。 相似文献
5.
It is shown that, for the spectrum analysis of digital quasi-periodic signals, one must use a procedure based on approximating the sequence of data readouts by a first-order trigonometric polynomial with a varying frequency of its harmonic functions. 相似文献
6.
7.
8.
Analysis of non-stationary electrochemical oscillations emerges utilization of the techniques allowing an observation of time evolution of their parameters such as instantaneous frequency, amplitude or frequency band. An algorithm of extraction of these parameters can be based on one of linear or quadratic time-frequency representations of oscillations record. In this paper, the authors present representatives of such transformations (Choi-Williams and Cone-shaped) originating from one of the most popular joint time-frequency energy distribution—Wigner-Ville distribution. Short introduction to the mathematics of the topic discussed is provided, then the authors present an example of application in the analysis of current oscillations of copper dissolution process. 相似文献
9.
10.