全文获取类型
收费全文 | 8892篇 |
免费 | 270篇 |
国内免费 | 644篇 |
专业分类
系统科学 | 1451篇 |
丛书文集 | 254篇 |
教育与普及 | 1966篇 |
理论与方法论 | 156篇 |
现状及发展 | 62篇 |
研究方法 | 3篇 |
综合类 | 5872篇 |
自然研究 | 42篇 |
出版年
2023年 | 53篇 |
2022年 | 93篇 |
2021年 | 133篇 |
2020年 | 57篇 |
2019年 | 70篇 |
2018年 | 99篇 |
2017年 | 149篇 |
2016年 | 156篇 |
2015年 | 175篇 |
2014年 | 229篇 |
2013年 | 151篇 |
2012年 | 176篇 |
2011年 | 232篇 |
2010年 | 242篇 |
2009年 | 185篇 |
2008年 | 234篇 |
2007年 | 388篇 |
2006年 | 482篇 |
2005年 | 609篇 |
2004年 | 349篇 |
2003年 | 469篇 |
2002年 | 291篇 |
2001年 | 391篇 |
2000年 | 354篇 |
1999年 | 268篇 |
1998年 | 161篇 |
1997年 | 118篇 |
1996年 | 111篇 |
1995年 | 97篇 |
1994年 | 117篇 |
1993年 | 163篇 |
1992年 | 142篇 |
1991年 | 131篇 |
1990年 | 108篇 |
1989年 | 137篇 |
1988年 | 189篇 |
1987年 | 198篇 |
1986年 | 236篇 |
1985年 | 218篇 |
1984年 | 233篇 |
1983年 | 218篇 |
1982年 | 212篇 |
1981年 | 180篇 |
1980年 | 151篇 |
1979年 | 69篇 |
1959年 | 62篇 |
1958年 | 80篇 |
1957年 | 48篇 |
1956年 | 49篇 |
1955年 | 58篇 |
排序方式: 共有9806条查询结果,搜索用时 640 毫秒
151.
Efficient structures for wideband digital receiver 总被引:1,自引:0,他引:1
Wang Hong Lu Youxin Wang Xuegang & Wan Yonglun Univ. of Electronic Science Technology of China Chengdu P. R. China 《系统工程与电子技术(英文版)》2006,17(3):483-486
1 .INTRODUCTIONWith the development of high perfor mance ana-logue-to-digital converters ( ADC) , applicationspecific integrated circuit ( ASIC) devices anddigital signal processing ( DSP) technology , dig-ital receiver has increasingly become popular inrecent years[1 ~7]. The digital receiver is a typi-cal application of software radio in radar . Itsmain purpose is to move the digital conversionprocess closer to the antenna and execute mainfunctions on general hardware . But the sign… 相似文献
152.
Sensor management based on fisher information gain 总被引:2,自引:0,他引:2
Tian Kangsheng~ & Zhu Guangxi~ . Dept. of Telecommunication Engineering Huazhong Univ. of Science & Technology Wuhan P. R. China . Dept. of Command Automation Engineering Airforce Radar Academy Wuhan P. R. China 《系统工程与电子技术(英文版)》2006,17(3):531-534
1 .INTRODUCTIONSensor management can be described as a systemor process that provides automatic or semi-auto-matic control of a group of sensors[1]. The basicobjective of sensor management is to select rightsensors to do the right service on the right targetat right ti me based on external measurements orcriteria[2]. A variety of techniques have been pro-posed or appliedtothe area of sensor management .One of the first articles to apply opti mization tech-nique to sensor management is by … 相似文献
153.
Chen Niansheng~ Li Layuan~ & Dong Wushi~ .School of Computer Science Wuhan Univ. of Technlogy Wuhan R. R. China .Dept.of Computer Science Hubei Normal Univ. Wuhan P. R. China 《系统工程与电子技术(英文版)》2006,17(3):642-647
1 .INTRODUCTIONA mobile Ad hoc network refers to a temporal multi-hop autonomy system,whichis constituted by a groupof mobile nodes containing wireless send-receive equip-ments[1].It possesses manycharacteristics-fast-deploy-able,self-organized,acentric , movable and of multi-hop.It can be wildly applied to many fields ,such asnational defense,emergency and disaster ,scientificin-vestigation and exploration etc .,and uponthat ,it hasgreat prospects[1 ,3 6]. With the wide spread of mo-bile… 相似文献
154.
Gan Rongbing & Wang Jianguo .National Electronic Warfare Lab Chengdu P.R.China .School of Electronic Engineering Univ. of Electronic Science Techndogy Chengdu P. R. China 《系统工程与电子技术(英文版)》2006,17(4):717-721
1. INTRODUCTION Many researches have been made on automatic target recognition (ATR) from SAR images in the past few years. Lincoln Laboratory has developed a complete, end-to-end ATR system[1-4]. The whole system inclu- des three stages: detection (or prescreening), discri- mination and classification. In the detection stage, a two-parameter CFAR (constant false alarm rate) detector is used as a prescreener to select candidate targets in an SAR image on the basis of local brightne… 相似文献
155.
Zhang Yougang & Xu Bugong Coll. of Automatic Science & Engineering South China Univ. of Technology Guangzhou P. R. China 《系统工程与电子技术(英文版)》2006,17(4):836-845
1. INTRODUCTION Large-scale dynamic system theory has been intensi- vely studied during the past decade[1~3], but for fuzzy large-scale systems, namely large-scale systems comp- osed of a series of fuzzy subsystems, has been seldom done in literature. In Ref.[4], decentralized stabiliz- ation problem of fuzzy large-scale systems composed of a series of fuzzy subsystems was considered. Sufficient conditions for asymptotic stability of the fuzzy large-scale system and design methods of dec… 相似文献
156.
Liu ChenFirst Inst. Equipment Research Inst. of Second Artillery Beijing P. R. China 《系统工程与电子技术(英文版)》2006,17(4):901-909
1. INTRODUCTION Weapon equipments acquisition and demonstration has become more and more prominent in the informationalized war conditions while operational effectiveness evaluation is its core part. The compl- exity and uncertainty of weapon systems operational effectiveness evaluation make traditional analysis methods or expert evaluation methods less effective to solve problems. Simulation based operational effe- ctiveness evaluation is an efficient solution. The increased complexity o… 相似文献
157.
158.
随着时间的推移,我们的世界似乎在不断地变小,不仅如此,新的发明创造也在向着更小更精细的方向发展。然而,这些“小玩意儿”在发展的道路上总会遭遇瓶颈,至少在以摩尔定律(Moore's Law)为准规则的计算世界会这样。如果根据英特尔公司(INTEL)创办人之一Gordon Moore的建议,即一个电脑芯片上所能容纳的晶体管数目每隔18~24个月增加一倍,那么一块硅片上 相似文献
159.
160.
Global warming: Take action or wait? 总被引:1,自引:0,他引:1
W.S.Broecder 《科学通报(英文版)》2006,51(9):1018-1029
Of all the changes wrought by human activity, the buildup in our atmosphere of the greenhouse gases, carbon dioxide, methane and nitrous oxide, has gener- ated the most contentious debate. Environmentalists warn that in the absence of firm action, over th… 相似文献