首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   44056篇
  免费   4846篇
  国内免费   3087篇
电工技术   3559篇
技术理论   1篇
综合类   3927篇
化学工业   5144篇
金属工艺   1878篇
机械仪表   2753篇
建筑科学   3387篇
矿业工程   1286篇
能源动力   1550篇
轻工业   1773篇
水利工程   1121篇
石油天然气   2319篇
武器工业   1022篇
无线电   7154篇
一般工业技术   4474篇
冶金工业   1601篇
原子能技术   428篇
自动化技术   8612篇
  2024年   205篇
  2023年   622篇
  2022年   1060篇
  2021年   1051篇
  2020年   1203篇
  2019年   1043篇
  2018年   1015篇
  2017年   1287篇
  2016年   1444篇
  2015年   1500篇
  2014年   2213篇
  2013年   2340篇
  2012年   2908篇
  2011年   3199篇
  2010年   2473篇
  2009年   2616篇
  2008年   2838篇
  2007年   3512篇
  2006年   3101篇
  2005年   2684篇
  2004年   2259篇
  2003年   2010篇
  2002年   1591篇
  2001年   1392篇
  2000年   1196篇
  1999年   925篇
  1998年   770篇
  1997年   621篇
  1996年   540篇
  1995年   472篇
  1994年   405篇
  1993年   280篇
  1992年   270篇
  1991年   187篇
  1990年   169篇
  1989年   138篇
  1988年   105篇
  1987年   69篇
  1986年   62篇
  1985年   36篇
  1984年   33篇
  1983年   24篇
  1982年   24篇
  1981年   16篇
  1980年   14篇
  1979年   7篇
  1966年   6篇
  1964年   4篇
  1957年   8篇
  1955年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
In this research, we propose a novel framework referred to as collective game behavior decomposition where complex collective behavior is assumed to be generated by aggregation of several groups of agents following different strategies and complexity emerges from collaboration and competition of individuals. The strategy of an agent is modeled by certain simple game theory models with limited information. Genetic algorithms are used to obtain the optimal collective behavior decomposition based on history data. The trained model can be used for collective behavior prediction. For modeling individual behavior, two simple games, the minority game and mixed game are investigated in experiments on the real-world stock prices and foreign-exchange rate. Experimental results are presented to show the effectiveness of the new proposed model.  相似文献   
2.
3.
Human mobility prediction is of great advantage in route planning and schedule management. However, mobility data is a high-dimensional dataset in which multi-context prediction is difficult in a single model. Mobility data can usually be expressed as a home event, a work event, a shopping event and a traveling event. Previous works have only been able to learn and predict one type of mobility event and then integrate them. As the tensor model has a strong ability to describe high-dimensional information, we propose an algorithm to predict human mobility in tensors of location context data. Using the tensor decomposition method, we extract human mobility patterns with multiple expressions and then synthesize the future mobility event based on mobility patterns. The experiment is based on real-world location data and the results show that the tensor decomposition method has the highest accuracy in terms of prediction error among the three methods. The results also prove the feasibility of our multi-context prediction model.  相似文献   
4.
Using a comprehensive set of drop weight impact test data (h50) newly compiled from literature for 308 materials, a recent approach to predict impact sensitivities of nitro compounds is generalized to most explosive substances of interest. Compared to previous ones, this procedure is more thoroughly validated and exhibits a good predictive value. Furthermore, it yields new insight into the physical mechanisms involved, explaining for instance the unexpected desensitization of some oxygen-deficient triazoles upon nitration.  相似文献   
5.
Undoped and fluorine doped ZnO thin films were deposited onto glass substrates using successive ionic layer adsorption and reaction (SILAR) technique and then annealed at 350 °C in vacuum ambience. The F doping level was varied from 0 to 15 at% in steps of 5 at%. The XRD analysis showed that all the films are polycrystalline with hexagonal wurtzite structure and preferentially oriented along the (002) plane. Crystallite sizes were found to increase when 5 at% of F is doped and then decreased with further doping. It was seen from the SEM images that the doping causes remarkable changes in the surface morphology and the annealing treatment results in well-defined grains with an improvement in the grain size irrespective of doping level. All the films exhibit good transparency (>70%) after vacuum annealing. Electrical resistivity of the film was found to be minimum (1.32×10−3 Ω cm) when the fluorine doping level was 5 at%.  相似文献   
6.
移动通信系统中功率控制研究   总被引:2,自引:0,他引:2  
李蕾 《信息技术》2006,30(11):83-85
在阐述功率控制在移动通信系统中的发展过程的基础上,着重研究了WCDMA系统的功率控制,最后对功率控制未来的研究方向做了简要的分析。  相似文献   
7.
天然气水合物和天然气脱水新工艺探讨   总被引:3,自引:0,他引:3  
探讨了天然气水合物的发展过程、形成条件以及对天然气输送管道的腐蚀堵塞作用,对我国天然气脱水创新技术———膜法脱水、汽提脱水的原理与工艺过程进行了全面论述。考察了气体处理量及操作压力等对我国1.2×105m3/d天然气膜法脱水的工业试验装置的脱水过程的影响。  相似文献   
8.
From its foundation until 2004, ETRI has registered over 1,000 US patents. This letter analyzes the characteristics of these patents and addresses the explanatory factors affecting their citation counts. For explanatory variables, research team related variables, invention specific variables, and geographical domain related variables are suggested. Zero‐altered count data models are used to test the impact of independent variables. A key finding is that technological cumulativeness, the scale of invention, outputs in the electronic field, and the degree of dependence on the US technology domain positively affect the citation counts of ETRI‐invented US patents. The magnitude of international presence appears to negatively affect the citation counts of ETRI‐invented US patents.  相似文献   
9.
地震平衡技术是一种在地震反演中改善井震关系的新技术。它通过单井对比、空间分形建模以及平衡处理的手段 ,克服地震反演中子波空变的影响 ,使得经过地震平衡技术处理的地震剖面井震关系得到较好改善 ,从而可以用统一的子波对研究区的地震资料进行反演  相似文献   
10.
在数据采集中采用带通采样,可大大降低采样率,但系统中的抗混叠滤波器会造成相位的非线性。采用对滤波后的信号进行带通采样,然后再用FRR滤波器校正相位的非线性,从而不失真地还原原信号,最后在Matlab中进行仿真,验证了该方法的有效性。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号