全文获取类型
收费全文 | 5397篇 |
免费 | 922篇 |
国内免费 | 660篇 |
专业分类
电工技术 | 416篇 |
综合类 | 1074篇 |
化学工业 | 102篇 |
金属工艺 | 44篇 |
机械仪表 | 290篇 |
建筑科学 | 122篇 |
矿业工程 | 57篇 |
能源动力 | 82篇 |
轻工业 | 126篇 |
水利工程 | 93篇 |
石油天然气 | 135篇 |
武器工业 | 48篇 |
无线电 | 814篇 |
一般工业技术 | 441篇 |
冶金工业 | 32篇 |
原子能技术 | 33篇 |
自动化技术 | 3070篇 |
出版年
2024年 | 20篇 |
2023年 | 62篇 |
2022年 | 109篇 |
2021年 | 122篇 |
2020年 | 186篇 |
2019年 | 206篇 |
2018年 | 212篇 |
2017年 | 157篇 |
2016年 | 220篇 |
2015年 | 260篇 |
2014年 | 354篇 |
2013年 | 392篇 |
2012年 | 453篇 |
2011年 | 428篇 |
2010年 | 365篇 |
2009年 | 392篇 |
2008年 | 420篇 |
2007年 | 459篇 |
2006年 | 335篇 |
2005年 | 261篇 |
2004年 | 245篇 |
2003年 | 235篇 |
2002年 | 164篇 |
2001年 | 128篇 |
2000年 | 117篇 |
1999年 | 86篇 |
1998年 | 99篇 |
1997年 | 68篇 |
1996年 | 57篇 |
1995年 | 61篇 |
1994年 | 57篇 |
1993年 | 45篇 |
1992年 | 39篇 |
1991年 | 36篇 |
1990年 | 35篇 |
1989年 | 23篇 |
1988年 | 19篇 |
1987年 | 10篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1961年 | 1篇 |
1960年 | 1篇 |
1959年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有6979条查询结果,搜索用时 15 毫秒
1.
In this paper, we investigate how adaptive operator selection techniques are able to efficiently manage the balance between exploration and exploitation in an evolutionary algorithm, when solving combinatorial optimization problems. We introduce new high level reactive search strategies based on a generic algorithm's controller that is able to schedule the basic variation operators of the evolutionary algorithm, according to the observed state of the search. Our experiments on SAT instances show that reactive search strategies improve the performance of the solving algorithm. 相似文献
2.
3.
4.
彭威城 《电信工程技术与标准化》2019,32(10)
高铁移动网络覆盖是国内三大通信运营商的一个重点,而高铁隧道内移动网络覆盖更是运营商的一大难点痛点。文章根据我国中部省份某高铁线路覆盖规划实例,采用“设备+POI+泄漏电缆”模式,即三家运营商信号源设备通过同一POI(point of interface,多系统接入平台)接入,信号输出到泄漏电缆进行隧道覆盖,隧道口场坪站安装宽频切换天线对隧道外进行延伸覆盖,通过链路预算合理布置各运营商主设备信号源,从而实现隧道到室外的无缝覆盖。最后,根据已有成熟网络覆盖解决方案,对未来5G高铁隧道移动网络覆盖方案进行了探讨。 相似文献
5.
Miroslav Kárný Marko Ruman 《International Journal of Adaptive Control and Signal Processing》2021,35(5):660-675
Any knowledge extraction relies (possibly implicitly) on a hypothesis about the modelled-data dependence. The extracted knowledge ultimately serves to a decision-making (DM). DM always faces uncertainty and this makes probabilistic modelling adequate. The inspected black-box modeling deals with “universal” approximators of the relevant probabilistic model. Finite mixtures with components in the exponential family are often exploited. Their attractiveness stems from their flexibility, the cluster interpretability of components and the existence of algorithms for processing high-dimensional data streams. They are even used in dynamic cases with mutually dependent data records while regression and auto-regression mixture components serve to the dependence modeling. These dynamic models, however, mostly assume data-independent component weights, that is, memoryless transitions between dynamic mixture components. Such mixtures are not universal approximators of dynamic probabilistic models. Formally, this follows from the fact that the set of finite probabilistic mixtures is not closed with respect to the conditioning, which is the key estimation and predictive operation. The paper overcomes this drawback by using ratios of finite mixtures as universally approximating dynamic parametric models. The paper motivates them, elaborates their approximate Bayesian recursive estimation and reveals their application potential. 相似文献
6.
Hai Huang Haichao An Haibo Ma Shenyan Chen 《International journal for numerical methods in engineering》2019,117(3):291-315
This work presents an engineering method for optimizing structures made of bars, beams, plates, or a combination of those components. Corresponding problems involve both continuous (size) and discrete (topology) variables. Using a branched multipoint approximate function, which involves such mixed variables, a series of sequential approximate problems are constructed to make the primal problem explicit. To solve the approximate problems, genetic algorithm (GA) is utilized to optimize discrete variables, and when calculating individual fitness values in GA, a second-level approximate problem only involving retained continuous variables is built to optimize continuous variables. The solution to the second-level approximate problem can be easily obtained with dual methods. Structural analyses are only needed before improving the branched approximate functions in the iteration cycles. The method aims at optimal design of discrete structures consisting of bars, beams, plates, or other components. Numerical examples are given to illustrate its effectiveness, including frame topology optimization, layout optimization of stiffeners modeled with beams or shells, concurrent layout optimization of beam and shell components, and an application in a microsatellite structure. Optimization results show that the number of structural analyses is dramatically decreased when compared with pure GA while even comparable to pure sizing optimization. 相似文献
7.
8.
中国电信企业经过多年的高速发展,逐渐步入成熟期,增长率下降、利润降低将是必然趋势,因此目前亟需探索新的运营模式,向综合型全业务电信运营商的方向发展。法国电信集团历史悠久,市场转型起步早.其发展经验有许多地方值得借鉴,包括法国电信集团具有特色的品牌战咯、灵活的经营模式、为企业提供全方位服务的经营手段。中国电信企业应积极开展全业务经营,加快发展企业网市场,完善合作运营模式,争取早日走向世界。 相似文献
9.
10.