全文获取类型
收费全文 | 8144篇 |
免费 | 580篇 |
国内免费 | 383篇 |
专业分类
电工技术 | 586篇 |
技术理论 | 1篇 |
综合类 | 478篇 |
化学工业 | 973篇 |
金属工艺 | 1307篇 |
机械仪表 | 552篇 |
建筑科学 | 275篇 |
矿业工程 | 136篇 |
能源动力 | 349篇 |
轻工业 | 757篇 |
水利工程 | 44篇 |
石油天然气 | 195篇 |
武器工业 | 50篇 |
无线电 | 1027篇 |
一般工业技术 | 913篇 |
冶金工业 | 472篇 |
原子能技术 | 100篇 |
自动化技术 | 892篇 |
出版年
2024年 | 38篇 |
2023年 | 137篇 |
2022年 | 291篇 |
2021年 | 313篇 |
2020年 | 250篇 |
2019年 | 234篇 |
2018年 | 189篇 |
2017年 | 280篇 |
2016年 | 276篇 |
2015年 | 326篇 |
2014年 | 430篇 |
2013年 | 466篇 |
2012年 | 559篇 |
2011年 | 628篇 |
2010年 | 480篇 |
2009年 | 601篇 |
2008年 | 522篇 |
2007年 | 544篇 |
2006年 | 478篇 |
2005年 | 313篇 |
2004年 | 276篇 |
2003年 | 252篇 |
2002年 | 212篇 |
2001年 | 182篇 |
2000年 | 175篇 |
1999年 | 126篇 |
1998年 | 95篇 |
1997年 | 89篇 |
1996年 | 66篇 |
1995年 | 42篇 |
1994年 | 37篇 |
1993年 | 29篇 |
1992年 | 42篇 |
1991年 | 11篇 |
1990年 | 26篇 |
1989年 | 20篇 |
1988年 | 15篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1951年 | 1篇 |
排序方式: 共有9107条查询结果,搜索用时 15 毫秒
31.
This paper addresses the question: at the level of cortical cells present in the primary area V1, is the information sufficient to extract the local perspective from the texture? Starting from a model of complex cells in visual area V1, we propose a biologically plausible algorithm for frequency analysis applied to the shape from texture problem. First, specific log-normal filters are designed in replacement of the classical Gabor filters because of their theoretical properties and of their biological plausibility. These filters are separable in frequency and orientation and they better sample the image spectrum which makes them appropriate for any pattern analysis technique. A method to estimate the local frequency in the image, which discards the need to choose the best local scale, is designed. Based on this frequency analysis model, a local decomposition of the image into patches leads to the estimation of the local frequency variation which is used to solve the problem of recovering the shape from the texture. From the analytical relation between the local frequency and the geometrical parameters, under perspective projection, it is possible to recover the orientation and the shape of the original image. The accuracy of the method is evaluated and discussed on different kind of textures, both regular and irregular, with planar and curved surfaces and also on natural scenes and psychophysical stimuli. It compares favorably to the best existing methods, with in addition, a low computational cost. The biological plausibility of the model is finally discussed. 相似文献
32.
柳岸 《数字社区&智能家居》2009,5(2):986-987
该文介绍了一种电动自行车控制器的设计过程。控制器以PIC16F876为核心,驱动直流无刷电机,实现简单的电动自行车控制功能。 相似文献
33.
34.
盛存银 《自动化与仪器仪表》2009,(2):47-49
利用列车运行图,采用模拟分析的方法,分析计算了双线自动闭塞线路上V型天窗和X型天窗的在空间域上列车运行线集,由此得出了开设X型天窗比V型天窗使列车正常运行所要受的约束条件多。在此基础上提出了V—X混合型天窗,经计算表明,该维修天窗性能优于V型和X型天窗。 相似文献
35.
Eugene Pozhidaev Vladimir Chigrinov Gurumurthy Hegde Peizhi Xu 《Journal of the Society for Information Display》2009,17(1):53-59
Abstract— Multistable electro‐optical modes exist under certain conditions in ferroelectric liquid‐crystal (FLC) cells, which means that any light‐transmission level can be memorized after the driving voltage is switched off. The multistability is responsible for three new electro‐optical modes with different shapes of the gray‐scale curve that can be either S‐shaped (double or single dependent upon the applied‐voltage pulse sequence and boundary conditions) or V‐shaped dependent upon boundary conditions and FLC cell parameters. The origin of these modes will be described. 相似文献
36.
In this paper, we present an analysis and synthesis approach for guaranteeing that the phase of a single-input, single-output closed-loop transfer function is contained in the interval [−α,α] for a given α>0 at all frequencies. Specifically, we first derive a sufficient condition involving a frequency domain inequality for guaranteeing a given phase constraint. Next, we use the Kalman–Yakubovich–Popov theorem to derive an equivalent time domain condition. In the case where , we show that frequency and time domain sufficient conditions specialize to the positivity theorem. Furthermore, using linear matrix inequalities, we develop a controller synthesis approach for guaranteeing a phase constraint on the closed-loop transfer function. Finally, we extend this synthesis approach to address mixed gain and phase constraints on the closed-loop transfer function. 相似文献
37.
基于单片机的温室自动控制系统 总被引:2,自引:0,他引:2
介绍一种基于单片机的温室温度自动控制系统。热敏电阻采集温室内的温度,单片机控制温度在液晶屏上实时显示,利用上位机进行实时监控,通过串行通信将采集到的数据送至上位机,应用系统自带的超级终端软件实现温室温度在上位机中的实时显示。 相似文献
38.
39.
Saleh Albahli 《计算机系统科学与工程》2022,43(2):701-717
While the internet has a lot of positive impact on society, there are negative components. Accessible to everyone through online platforms, pornography is, inducing psychological and health related issues among people of all ages. While a difficult task, detecting pornography can be the important step in determining the porn and adult content in a video. In this paper, an architecture is proposed which yielded high scores for both training and testing. This dataset was produced from 190 videos, yielding more than 19 h of videos. The main sources for the content were from YouTube, movies, torrent, and websites that hosts both pornographic and non-pornographic contents. The videos were from different ethnicities and skin color which ensures the models can detect any kind of video. A VGG16, Inception V3 and Resnet 50 models were initially trained to detect these pornographic images but failed to achieve a high testing accuracy with accuracies of 0.49, 0.49 and 0.78 respectively. Finally, utilizing transfer learning, a convolutional neural network was designed and yielded an accuracy of 0.98. 相似文献
40.
Phase Separation Derived Core/Shell Structured Cu11V6O26/V2O5 Microspheres: First Synthesis and Excellent Lithium‐Ion Anode Performance with Outstanding Capacity Self‐Restoration 下载免费PDF全文
Jian Pei Gang Chen Qiang Zhang Changfeng Bie Jingxue Sun 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(17)
Novel amorphous vanadium oxide coated copper vanadium oxide (Cu11V6O26/V2O5) microspheres with 3D hierarchical architecture have been successfully prepared via a microwave‐assisted solution method and subsequent annealing induced phase separation process. Pure Cu11V6O26 microspheres without V2O5 coating are also obtained by an H2O2 solution dissolving treatment. When evaluated as an anode material for lithium‐ion batteries (LIBs), the as‐synthesized hybrid exhibits large reversible capacity, excellent rate capability, and outstanding capacity self‐recovery. Under the condition of high current density of 1 A g?1, the 3D hierarchical Cu11V6O26/V2O5 hybrid maintains a reversible capacity of ≈1110 mA h g?1. Combined electrochemical analysis and high‐resolution transmission electron microscopy observation during cycling reveals that the amorphous V2O5 coating plays an important role on enhancing the electrochemical performances and capacity self‐recovery, which provides an active amorphous protective layer and abundant grain interfaces for efficient inserting and extracting of Li‐ion. As a result, this new copper vanadium oxide hybrid is proposed as a promising anode material for LIBs. 相似文献