全文获取类型
收费全文 | 19742篇 |
免费 | 2827篇 |
国内免费 | 1590篇 |
专业分类
电工技术 | 3937篇 |
技术理论 | 4篇 |
综合类 | 2560篇 |
化学工业 | 968篇 |
金属工艺 | 365篇 |
机械仪表 | 1172篇 |
建筑科学 | 2139篇 |
矿业工程 | 635篇 |
能源动力 | 854篇 |
轻工业 | 611篇 |
水利工程 | 353篇 |
石油天然气 | 586篇 |
武器工业 | 275篇 |
无线电 | 2603篇 |
一般工业技术 | 1428篇 |
冶金工业 | 673篇 |
原子能技术 | 122篇 |
自动化技术 | 4874篇 |
出版年
2024年 | 175篇 |
2023年 | 476篇 |
2022年 | 766篇 |
2021年 | 945篇 |
2020年 | 917篇 |
2019年 | 696篇 |
2018年 | 612篇 |
2017年 | 772篇 |
2016年 | 818篇 |
2015年 | 964篇 |
2014年 | 1605篇 |
2013年 | 1281篇 |
2012年 | 1593篇 |
2011年 | 1605篇 |
2010年 | 1272篇 |
2009年 | 1265篇 |
2008年 | 1183篇 |
2007年 | 1266篇 |
2006年 | 1199篇 |
2005年 | 971篇 |
2004年 | 786篇 |
2003年 | 679篇 |
2002年 | 533篇 |
2001年 | 435篇 |
2000年 | 352篇 |
1999年 | 216篇 |
1998年 | 156篇 |
1997年 | 116篇 |
1996年 | 97篇 |
1995年 | 91篇 |
1994年 | 73篇 |
1993年 | 49篇 |
1992年 | 37篇 |
1991年 | 27篇 |
1990年 | 26篇 |
1989年 | 21篇 |
1988年 | 13篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 5篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1977年 | 3篇 |
1972年 | 3篇 |
1965年 | 2篇 |
1962年 | 4篇 |
1959年 | 2篇 |
1958年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Against the background of smart manufacturing and Industry 4.0, how to achieve real-time scheduling has become a problem to be solved. In this regard, automatic design for shop scheduling based on hyper-heuristics has been widely studied, and a number of reviews and scheduling algorithms have been presented. Few studies, however, have specifically discussed the technical points involved in algorithm development. This study, therefore, constructs a general framework for automatic design for shop scheduling strategies based on hyper-heuristics, and various state-of-the-art technical points in the development process are summarized. First, we summarize the existing types of shop scheduling strategies and classify them using a new classification method. Second, we summarize an automatic design algorithm for shop scheduling. Then, we investigate surrogate-assisted methods that are popular in the current algorithm field. Finally, current problems and challenges are discussed, and potential directions for future research are proposed. 相似文献
2.
3.
4.
在干扰条件下,卫星导航抗干扰波束形成算法往往需要卫星信号波达方向(Direction-of-Arrival,DOA)的先验信息。但当存在低信噪比信号或主动干扰源时,常规的DOA估计算法性能急剧下降甚至失效。针对此问题,提出了一种被干扰信号压制的低信噪比“北斗”信号的DOA估计算法。该算法首先通过对接收信号进行子空间投影抑制干扰信号,然后对抑制干扰后的信号进行解扩重构处理,最后通过多重信号分类算法完成对“北斗”信号的DOA估计。仿真结果表明,在干扰信号干信比80 dB条件下,“北斗”信号DOA估计误差在5°以内,为下一步进行波束形成计算提供了高精度的入射角信息。 相似文献
5.
《International Journal of Hydrogen Energy》2020,45(38):19720-19732
The need to reduce PEMFC systems cost as well as to increase their durability is crucial for their integration in various applications and especially for transport applications. A new simplified architecture of the anode circuit called Alternating Fuel Feeding (AFF) offers to reduce the development costs. Requiring a new stack concept, it combines the simplicity of Dead-End Anode (DEA) with the operation advantages of the hydrogen recirculation. The three architectures (DEA, recirculation and AFF) are compared in terms of performance on a 5-kW test bench in automotive conditions, through a sensitivity analysis. A gain of 17% on the system efficiency is observed when switching from DEA to AFF. Moreover, similar performances are obtained both for AFF and for recirculation after an accurate optimization of the AFF tuning parameters. Based on DoE data, a gain of 25% on the weight of the anodic line has been identified compared to pulsed ejector architecture and 43% with the classic recirculation architecture with blower only (Miraï). 相似文献
6.
A method for estimating the sway angle using an observer has already been proposed. The state observer estimates the sway angle accurately and must use the detected sway angle value. However, the estimated sway angle has an error owing to rope length error, friction force, and wind. Moreover, the container mass cannot be determined, and therefore the observer parameter is not suitable. We already proposed robust antisway control for overcoming rope length error without adding a new sensor. Further, we designed a friction disturbance observer to cancel out the influence of the friction force. In this paper, we first propose a container mass estimation method when a crane system performs rolling up control. The observer parameter can be selected using the estimated mass value. Second, in crane parallel shift control, we propose a robust antisway control even when there is a wind disturbance. We design a wind disturbance observer and propose a wind disturbance estimator to separate the friction observer output from the wind disturbance observer output. We confirm through experiments that the proposed method can reduce vibration. 相似文献
7.
本文对运营商信息安全集中管控架构演进和信息安全管控策略面临的问题进行了深入分析,提出了信息安全集中管控架构的演进方向建议及对信息安全监控策略工作优化的若干意见。 相似文献
8.
在通讯设备爆炸式增长的时代,移动边缘计算作为5G通讯技术的核心技术之一,对其进行合理的资源分配显得尤为重要。移动边缘计算的思想是把云计算中心下沉到基站部署(边缘云),使云计算中心更加靠近用户,以快速解决计算资源分配问题。但是,相对于大型的云计算中心,边缘云的计算资源有限,传统的虚拟机分配方式不足以灵活应对边缘云的计算资源分配问题。为解决此问题,提出一种根据用户综合需求变化的动态计算资源和频谱分配算法(DRFAA),采用"分治"策略,并将资源模拟成"流体"资源进行分配,以寻求较大的吞吐量和较低的传输时延。实验仿真结果显示,动态计算资源和频谱分配算法可以有效地降低用户与边缘云之间的传输时延,也可以提高边缘云的吞吐量。 相似文献
9.
Self-adaptive surface measurements that can reduce data redundancy and improve time efficiency are in high demand in many fields of science and technology. For this purpose, a system implemented with Gaussian process (GP) adaptive sampling is developed. The non-parametric GP model is applied to reconstruct the topography and guide the subsequent sampling position, which is determined from the inference uncertainty estimation. A criterion is proposed to terminate the GP adaptive measurement automatically without any prior model or data of the topography. Experiments on typical surfaces validate the intelligence, adaptability, and high accuracy of the GP method along with the stabilization of the automatic iteration termination. Compared with traditional raster sampling, data redundancy is reduced and the time efficiency is improved without sacrificing the surface reconstruction accuracy. The proposed method can be implemented in other systems with similar measurement principles, thus benefitting surface characterizations. 相似文献
10.
我国的军工科研所成立于上世纪,它以军工项目的科研、预研为主,为我国的国防军工提供研发产品。伴随着我国经济实力的增强和科技军事力量的增长,军工科研院所也转变了原有的工业专属性质,走上了军民两用、寓军于民的道路,并在时代的进步中成为了我国先进装备制造业的重要科研力量和科技创新支柱。凸现军事工业“高、精、尖”的特点,以项目管理的优化为具体策略进行军工科研开发工作。 相似文献