全文获取类型
收费全文 | 54864篇 |
免费 | 3029篇 |
国内免费 | 1512篇 |
专业分类
电工技术 | 2861篇 |
技术理论 | 8篇 |
综合类 | 6061篇 |
化学工业 | 1460篇 |
金属工艺 | 478篇 |
机械仪表 | 968篇 |
建筑科学 | 31259篇 |
矿业工程 | 2011篇 |
能源动力 | 658篇 |
轻工业 | 431篇 |
水利工程 | 4730篇 |
石油天然气 | 872篇 |
武器工业 | 200篇 |
无线电 | 1345篇 |
一般工业技术 | 1117篇 |
冶金工业 | 1321篇 |
原子能技术 | 87篇 |
自动化技术 | 3538篇 |
出版年
2024年 | 122篇 |
2023年 | 354篇 |
2022年 | 810篇 |
2021年 | 1001篇 |
2020年 | 988篇 |
2019年 | 595篇 |
2018年 | 640篇 |
2017年 | 792篇 |
2016年 | 1183篇 |
2015年 | 1390篇 |
2014年 | 6525篇 |
2013年 | 3145篇 |
2012年 | 4428篇 |
2011年 | 4673篇 |
2010年 | 4262篇 |
2009年 | 4447篇 |
2008年 | 3933篇 |
2007年 | 4410篇 |
2006年 | 3260篇 |
2005年 | 2378篇 |
2004年 | 2168篇 |
2003年 | 1938篇 |
2002年 | 1516篇 |
2001年 | 1094篇 |
2000年 | 889篇 |
1999年 | 562篇 |
1998年 | 375篇 |
1997年 | 338篇 |
1996年 | 271篇 |
1995年 | 223篇 |
1994年 | 166篇 |
1993年 | 111篇 |
1992年 | 87篇 |
1991年 | 47篇 |
1990年 | 49篇 |
1989年 | 53篇 |
1988年 | 25篇 |
1987年 | 19篇 |
1986年 | 24篇 |
1985年 | 23篇 |
1984年 | 25篇 |
1983年 | 16篇 |
1982年 | 5篇 |
1978年 | 3篇 |
1965年 | 4篇 |
1963年 | 3篇 |
1960年 | 3篇 |
1958年 | 4篇 |
1957年 | 3篇 |
1955年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
如何在互联网时代打造一个信息化的管理模式,已经成为广大学校图书管理发展过程中亟待处理的问题。文章就互联网时代下的高职图书管理信息化建设进行了详细探讨,以期能够给广大同仁提供一些借鉴参考,共同为图书管理工作的现代化改革和发展贡献力量。 相似文献
2.
3.
Wenshu Chen Jiajun Gu Yongping Du Fang Song Fanxing Bu Jinghan Li Yang Yuan Ruichun Luo Qinglei Liu Di Zhang 《Advanced functional materials》2020,30(25)
Large‐scale production of hydrogen from water‐alkali electrolyzers is impeded by the sluggish kinetics of hydrogen evolution reaction (HER) electrocatalysts. The hybridization of an acid‐active HER catalyst with a cocatalyst at the nanoscale helps boost HER kinetics in alkaline media. Here, it is demonstrated that 1T–MoS2 nanosheet edges (instead of basal planes) decorated by metal hydroxides form highly active / heterostructures, which significantly enhance HER performance in alkaline media. Featured with rich / sites, the fabricated 1T–MoS2 QS/Ni(OH)2 hybrid (quantum sized 1T–MoS2 sheets decorated with Ni(OH)2 via interface engineering) only requires overpotentials of 57 and 112 mV to drive HER current densities of 10 and 100 mA cm?2, respectively, and has a low Tafel slope of 30 mV dec?1 in 1 m KOH. So far, this is the best performance for MoS2‐based electrocatalysts and the 1T–MoS2 QS/Ni(OH)2 hybrid is among the best‐performing non‐Pt alkaline HER electrocatalysts known. The HER process is durable for 100 h at current densities up to 500 mA cm?2. This work not only provides an active, cost‐effective, and robust alkaline HER electrocatalyst, but also demonstrates a design strategy for preparing high‐performance catalysts based on edge‐rich 2D quantum sheets for other catalytic reactions. 相似文献
4.
Laura Menini Corrado Possieri Antonio Tornambè 《International Journal of Adaptive Control and Signal Processing》2015,29(12):1578-1590
The main goal of this paper is to design a compensator able to restore the nominal behavior of a planar system, which is rendered chaotic by an unmeasurable sinusoidal disturbance input. To reach such a goal, some instruments, taken from algebraic geometry, are used to estimate the unmeasurable disturbance from the time derivatives of the output of the system and of the control input. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
5.
6.
与传统比例-积分-微分(PID)控制方法相比,滑模控制(SMC)方法可以比较容易地将不确定性纳入控制器设计中,从而增强系统的鲁棒性。探索了SMC技术在运载器主动段姿态控制中的工程应用,首先通过分析基于趋近律的SMC系统,提出了降低不连续切换项系数的需求,然后研究了基于干扰上界的SMC方法。三通道小偏差仿真结果验证了两种方法的控制效果,表明第2种控制器的鲁棒性更好,稳态误差小,同时发动机喷管摆角需求较小。 相似文献
7.
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
8.
土木工程施工课程作为土木工程及工程管理专业的学科基础课和核心专业课程,在疫情防控期间"停课不停教""停课不停学"的要求下,通过线上平台进行授课。由于土木工程施工课程内容庞杂、综合性强、实践性强,且章节之间关联性较弱,探究既能使学生快速适应,又能保证教学质量的在线教学方法至关重要。以华南某高校土木工程施工课程为例,基于中国大学MOOC、建筑云课、腾讯课堂、QQ群等线上平台讲授教学内容,并运用问卷调查对课程线上教学效果进行评价。结果表明,线上教学为学生提供了丰富灵活的学习方式,显著提高了学生的自主学习能力,扩大了学生的知识面,达到了较好的学习效果。 相似文献
9.
The purpose of feature construction is to create new higher-level features from original ones. Genetic Programming (GP) was usually employed to perform feature construction tasks due to its flexible representation. Filter-based approach and wrapper-based approach are two commonly used feature construction approaches according to their different evaluation functions. In this paper, we propose a hybrid feature construction approach using genetic programming (Hybrid-GPFC) that combines filter’s fitness function and wrapper’s fitness function, and propose a multiple feature construction method that stores top excellent individuals during a single GP run. Experiments on ten datasets show that our proposed multiple feature construction method (Fcm) can achieve better (or equivalent) classification performance than the single feature construction method (Fcs), and our Hybrid-GPFC can obtain better classification performance than filter-based feature construction approaches (Filter-GPFC) and wrapper-based feature construction approaches (Wrapper-GPFC) in most cases. Further investigations on combinations of constructed features and original features show that constructed features augmented with original features do not improve the classification performance comparing with constructed features only. The comparisons with three state-of-art methods show that in majority of cases, our proposed hybrid multiple feature construction approach can achieve better classification performance. 相似文献
10.
Vida Janbazi Mahnaz Hashemi 《International Journal of Adaptive Control and Signal Processing》2021,35(2):285-309
This article presents an adaptive neural compensation scheme for a class of large-scale time delay nonlinear systems in the presence of unknown dead zone, external disturbances, and actuator faults. In this article, the quadratic Lyapunov–Krasovskii functionals are introduced to tackle the system delays. The unknown functions of the system are estimated by using radial basis function neural networks. Furthermore, a disturbance observer is developed to approximate the external disturbances. The proposed adaptive neural compensation control method is constructed by utilizing a backstepping technique. The boundedness of all the closed-loop signals is guaranteed via Lyapunov analysis and the tracking errors are proved to converge to a small neighborhood of the origin. Simulation results are provided to illustrate the effectiveness of the proposed control approach. 相似文献