全文获取类型
收费全文 | 2792篇 |
免费 | 289篇 |
国内免费 | 222篇 |
专业分类
电工技术 | 127篇 |
技术理论 | 1篇 |
综合类 | 267篇 |
化学工业 | 206篇 |
金属工艺 | 17篇 |
机械仪表 | 73篇 |
建筑科学 | 317篇 |
矿业工程 | 35篇 |
能源动力 | 31篇 |
轻工业 | 118篇 |
水利工程 | 63篇 |
石油天然气 | 26篇 |
武器工业 | 10篇 |
无线电 | 350篇 |
一般工业技术 | 208篇 |
冶金工业 | 291篇 |
原子能技术 | 16篇 |
自动化技术 | 1147篇 |
出版年
2024年 | 27篇 |
2023年 | 94篇 |
2022年 | 130篇 |
2021年 | 138篇 |
2020年 | 105篇 |
2019年 | 90篇 |
2018年 | 62篇 |
2017年 | 87篇 |
2016年 | 138篇 |
2015年 | 135篇 |
2014年 | 137篇 |
2013年 | 206篇 |
2012年 | 155篇 |
2011年 | 174篇 |
2010年 | 138篇 |
2009年 | 176篇 |
2008年 | 157篇 |
2007年 | 167篇 |
2006年 | 164篇 |
2005年 | 154篇 |
2004年 | 125篇 |
2003年 | 98篇 |
2002年 | 88篇 |
2001年 | 77篇 |
2000年 | 66篇 |
1999年 | 32篇 |
1998年 | 41篇 |
1997年 | 32篇 |
1996年 | 17篇 |
1995年 | 16篇 |
1994年 | 12篇 |
1993年 | 11篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1986年 | 3篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1975年 | 2篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1964年 | 4篇 |
1961年 | 1篇 |
1959年 | 1篇 |
1958年 | 1篇 |
1955年 | 2篇 |
1954年 | 1篇 |
排序方式: 共有3303条查询结果,搜索用时 15 毫秒
1.
This paper proposes the application of Covariance Matrix Adaptation Evolution Strategy (CMA-ES) in fixed structure H∞ loop shaping controller design. Integral Time Absolute Error (ITAE) performance requirement is incorporated as a constraint with an objective of maximization of stability margin in the fixed structure H∞ loop shaping controller design problem. Pneumatic servo system, separating tower process and F18 fighter aircraft system are considered as test systems. The CMA-ES designed fixed structure H∞ loop-shaping controller is compared with the traditional H∞ loop shaping controller, non-smooth optimization and Heuristic Kalman Algorithm (HKA) based fixed structure H∞ loop shaping controllers in terms of stability margin. 20% perturbation in the nominal plant is used to validate the robustness of the CMA-ES designed H∞ loop shaping controller. The effect of Finite Word Length (FWL) is considered to show the implementation difficulties of controller in digital processors. Simulation results demonstrated that CMA-ES based fixed structure H∞ loop shaping controller is suitable for real time implementation with good robust stability and performance. 相似文献
2.
Myers Nicholas D.; Payment Craig A.; Feltz Deborah L. 《Canadian Metallurgical Quarterly》2004,8(3):182
This study examined reciprocal relationships between collective efficacy and team performance over a season of competition in women's intercollegiate ice hockey within weekends where the opponent was constant for 2 games. Collective efficacy beliefs within 12 teams were assessed prior to both games for at least 7 weekends. Team performance indexes produced an overall measure of performance for each game. The average influence of Saturday collective efficacy on Saturday performance was moderate and positive after controlling for Friday performance. The average influence of Friday performance on Saturday collective efficacy was small and positive after removing the influence of Friday collective efficacy from Friday performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
3.
Bandwidth Adaptation Algorithms for Adaptive Multimedia Services in Mobile Cellular Networks 总被引:3,自引:0,他引:3
The fluctuation of available link bandwidth in mobilecellular networks motivates the study of adaptive multimediaservices, where the bandwidth of an ongoing multimedia call can bedynamically adjusted. We analyze the diverse objectives of theadaptive multimedia framework and propose two bandwidth adaptationalgorithms (BAAs) that can satisfy these objectives. The firstalgorithm, BAA-RA, takes into consideration revenue and``anti-adaptation' where anti-adaptation means that a user feelsuncomfortable whenever the bandwidth of the user's call ischanged. This algorithm achieves near-optimal total revenue withmuch less complexity compared to an optimal BAA. The secondalgorithm, BAA-RF, considers revenue and fairness, and aims at themaximum revenue generation while satisfying the fairnessconstraint defined herein. Comprehensive simulation experimentsshow that the difference of the total revenue of BAA-RA and thatof an optimal BAA is negligible. Also, numerical results revealthat there is a conflicting relationship between anti-adaptationand fairness. 相似文献
4.
一种支持QoS的拓扑自适应动态组播路由算法 总被引:3,自引:0,他引:3
YAM、QoSMIC、DSDMR等一类支持QoS的动态组播路由算法允许组播成员动态地加入和离开,同时为接收方提供多个可选择的组播接入路径,以满足不同应用的QoS需求。但这些算法普遍存在控制信令开销大和结点加入时延长,可扩展性不好等问题。本文在分析这些算法的基础上,提出改进的支持QoS的动态组播路由算法,即拓扑自适应动态组播路由(Topology Adaptive Dynamic Multicast Routing,TADMR)算法。该算法避免了以往算法中大部分盲目的路径搜索,并使结点加入时延不再受限于固定的等待时钟,而与网络拓扑相自适应。性能分析和仿真结果表明,该算法具有较低的控制信令开销和结点加入时延,适用于各种网络规模和群组规模,具有良好的可扩展性。 相似文献
5.
本文介绍了广播发射台利用计算机技术、网络技术、遥控遥测技术、现代测试手段,对设备进行自动化控制与管理;实现设备技术指标自动测试,发射台无人值班、有人留守,建立机器的计算机档案制度,确保安全优质播出的方法和经验。 相似文献
6.
The long-term effects of the Cognitive Adaptation Theory Index (CATI) on psychological and physical health outcomes among men (n=199) and women (n=99) treated for coronary artery disease with percutaneous transluminal coronary angioplasty were examined. The CATI reflects a positive view of the self, a positive view of one's future, and a sense of personal control over daily life. This index was created from questionnaires administered during hospitalization for the initial angioplasty. Four years later, the CATI predicted positive adjustment to disease, even when initial adjustment was taken into consideration. In addition, the CATI predicted a reduced likelihood of sustaining a subsequent cardiac event over 4 yrs. This association was more robust for men. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
8.
HOU Xiao-lin LI Shu-bo YIN Chang-chuan YUE Guang-xin School of Telecommunication Engineering Beijing University of Posts Telecommunications Beijing P.R. China 《中国邮电高校学报(英文版)》2004,11(3)
1 Introduction Linkadaptationtechniqueisnowwidelyrecognizedasakeysolutiontoincreasethespectralefficiencyofwire lesssystems[1~ 3] .GPRS ,EDGE ,cdma2 0 0 0andWCDMAallincludelinkadaptationasameanstopro videhigherdatarates[4~ 5] .Torealizethepotentialoflinkadaptation ,reliablechannel predictionisneces sary[6 ] . Therearemanydifferentchannelpredictionmethodsavailablenow ,suchasLongRangePrediction(LRP) [6 ] ,predictionbasedonsubspacesignalprocess ingalgorithms[7] ,predictionbasedonFinit… 相似文献
9.
李文军 《沙洲职业工学院学报》2006,(4)
忘记历史就意味着背叛,张抗抗在《集体记忆》中描写史志工作者在搜集史料时遇到了这种背叛现象,知情人有意无意地患上了“集体忘却”症。通过梳理此症的主要表现,即强占记忆与摧毁记忆,指出其社会文化政治因素在于建国以来的主流思想。 相似文献
10.
政治共同民主为经济共同富裕提供制度基础和政治保障。其中,民主政治是实现共同富裕的前提,建立有效、灵活和合理的政府是关键,健全法制是实现共同富裕的保障。文化共同繁荣为共同富裕提供精神动力和智力支持。 相似文献