全文获取类型
收费全文 | 479244篇 |
免费 | 38601篇 |
国内免费 | 24354篇 |
专业分类
电工技术 | 32149篇 |
技术理论 | 67篇 |
综合类 | 65487篇 |
化学工业 | 51416篇 |
金属工艺 | 20483篇 |
机械仪表 | 30525篇 |
建筑科学 | 58173篇 |
矿业工程 | 24819篇 |
能源动力 | 15162篇 |
轻工业 | 22598篇 |
水利工程 | 21633篇 |
石油天然气 | 23083篇 |
武器工业 | 6256篇 |
无线电 | 35637篇 |
一般工业技术 | 31940篇 |
冶金工业 | 23224篇 |
原子能技术 | 4625篇 |
自动化技术 | 74922篇 |
出版年
2024年 | 1558篇 |
2023年 | 4522篇 |
2022年 | 9102篇 |
2021年 | 10798篇 |
2020年 | 11555篇 |
2019年 | 8846篇 |
2018年 | 8494篇 |
2017年 | 10893篇 |
2016年 | 13308篇 |
2015年 | 15319篇 |
2014年 | 29389篇 |
2013年 | 25194篇 |
2012年 | 33389篇 |
2011年 | 36166篇 |
2010年 | 28930篇 |
2009年 | 29520篇 |
2008年 | 27182篇 |
2007年 | 34838篇 |
2006年 | 32497篇 |
2005年 | 28095篇 |
2004年 | 23742篇 |
2003年 | 21314篇 |
2002年 | 17407篇 |
2001年 | 14744篇 |
2000年 | 12226篇 |
1999年 | 9685篇 |
1998年 | 7306篇 |
1997年 | 6169篇 |
1996年 | 5598篇 |
1995年 | 4661篇 |
1994年 | 4009篇 |
1993年 | 2932篇 |
1992年 | 2479篇 |
1991年 | 1869篇 |
1990年 | 1560篇 |
1989年 | 1388篇 |
1988年 | 1086篇 |
1987年 | 739篇 |
1986年 | 571篇 |
1985年 | 464篇 |
1984年 | 470篇 |
1983年 | 349篇 |
1982年 | 304篇 |
1981年 | 222篇 |
1980年 | 186篇 |
1979年 | 162篇 |
1978年 | 83篇 |
1977年 | 102篇 |
1975年 | 72篇 |
1959年 | 69篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Jean-Claude Malela-Majika Sandile Charles Shongwe Olatunde Adebayo Adeoti 《Quality and Reliability Engineering International》2021,37(8):3314-3322
The sensitivity of a monitoring scheme depends on many factors including the variance of the charting statistic which is very important in the computation of the control limits. This paper discusses the computation of the variance of the recently proposed hybrid homogeneously weighted moving average (HHWMA) scheme which was based on an incorrect assumption. The correct variance is used to evaluate the run-length characteristics of the HHWMA scheme. It is observed that the incorrect variance has a significant impact on the sensitivity (or performance) of the HHWMA scheme. 相似文献
2.
Elli Ntakou Ralph Masiello Farnaz Farzan Shay Bahramirad Aleksi Paaso M.A. Nayeem Maigha Maigha Daniel Kushner 《The Electricity Journal》2019,32(4):45-49
This paper presents part of the work ComEd and Quanta Technology have performed to quantify the locational and temporal value of DER to avoid distribution grid upgrade investments. It focuses on the formulation of a robust and efficient algorithm for DER optimal dispatch on a distribution feeder to mitigate the violation of current and voltage limits using the allocated cost of capacity and locational marginal value of real and reactive DER injection/withdrawal. 相似文献
3.
以重庆市甄子岩29号危岩体为研究对象,基于现场调查和分析解剖,建立UDEC离散元数值计算模型,对其演化变形过程进行模拟分析。研究表明,在巨大的自重作用下,由于基座岩体岩质软,岩体较破碎,且基座外侧为直立的陡崖,具有完整的临空面,从而使基座岩体易发生压缩流变及剪切流变,进而使危岩体存在滑移垮塌的危险。 相似文献
4.
目的研究蛋类礼盒包装结构的缓冲性能。方法以蛋类尺寸为基础,建立可发性聚乙烯(expandable polyethylene. EPE)缓冲单元结构和组合结构,进行静态仿真分析和实验验证,比较结构在形状、叠合层数、组合形式等参数变化时的载荷与位移。结果结构层数变化相同时,单元结构的极限载荷从143N增加到236 N,组合结构的极限载荷从224 N增加到476 N,均呈近线性增长。结论蛋类礼盒包装中,组合结构的承载能力优于单元结构,通过单元结构的组合,可满足不同蛋类的包装要求。 相似文献
5.
6.
Yasoub Eghbali Mahmoud Ferdosizade Naeiny 《International Journal of Communication Systems》2020,33(14)
In this paper, an off‐grid direction of arrival (DoA) estimation method is proposed for wideband signals. This method is based on the sparse representation (SR) of the array covariance matrix. Similar to the time domain DoA estimation methods, the correlation function of the sources was assumed to be the same and known. A new measurement vector is obtained using the lower‐left triangular elements of the covariance matrix. The DoAs are estimated by quantizing the entire range of continuous angle space into discrete grid points. However, the exact DoAs may be located between two grid points; therefore, this estimation has errors. The accuracy of DoA estimation is improved by the minimization of the difference between the new measurement vector and its estimated values. Simulation results revealed that the proposed method can enhance the DoA estimation accuracy of wideband signals. 相似文献
7.
8.
Output feedback controller for polytopic systems exploiting the direct searching of the design space
This paper deals with the problem of designing a robust static output feedback controller for polytopic systems. The current research that tackled this problem is mainly based on LMI method, which is conservative by nature. In this paper, a novel approach is proposed, which considers the design space of the controller parameters and iteratively partitions the space to small simplexes. Then, by assessing the stability in each simplex, the solution space for design parameters is directly determined. It has been theoretically proved that, if there exists a feasible solution in the design space, the algorithm can find it. To validate the result of the proposed approach, comparative simulation examples are given to illustrate the performance of the design methodology as compared to those of previous approaches. 相似文献
9.
Most real-world vehicle nodes can be structured into an interconnected network of vehicles. Through structuring these services and vehicle device interactions into multiple types, such internet of vehicles becomes multidimensional heterogeneous overlay networks. The heterogeneousness of the overlays makes it difficult for the overlay networks to coordinate with each other to improve their performance. Therefore, it poses an interesting but critical challenge to the effective analysis of heterogeneous virtual vehicular networks. A variety of virtual vehicular networks can be easily deployed onto the native network by applying the concept of SDN (Software Defined Networking). These virtual networks reflect their heterogeneousness due to their different performance goals, and they compete for the same physical resources of the underlying network, so that a sub-optimal performance of the virtual networks may be achieved. Therefore, we propose a Deep Reinforcement Learning (DRL) approach to make the virtual networks cooperate with each other through the SDN controller. A cooperative solution based on the asymmetric Nash bargaining is proposed for co-existing virtual networks to improve their performance. Moreover, the Markov Chain model and DRL resolution are introduced to leverage the heterogeneous performance goals of virtual networks. The implementation of the approach is introduced, and simulation results confirm the performance improvement of the latency sensitive, loss-rate sensitive and throughput sensitive heterogeneous vehicular networks using our cooperative solution. 相似文献
10.
Fog computing has emerged to support the requirements of IoT applications that could not be met by today’s solutions. Different initiatives have been presented to drive the development of fog, and much work has been done to improve certain aspects. However, an in-depth analysis of the different solutions, detailing how they can be integrated and applied to meet specific requirements, is still required. In this work, we present a unified architectural model and a new taxonomy, by comparing a large number of solutions. Finally, we draw some conclusions and guidelines for the development of IoT applications based on fog. 相似文献