全文获取类型
收费全文 | 30395篇 |
免费 | 2571篇 |
国内免费 | 1382篇 |
专业分类
电工技术 | 5799篇 |
综合类 | 2379篇 |
化学工业 | 1851篇 |
金属工艺 | 583篇 |
机械仪表 | 2410篇 |
建筑科学 | 1378篇 |
矿业工程 | 621篇 |
能源动力 | 1319篇 |
轻工业 | 900篇 |
水利工程 | 1020篇 |
石油天然气 | 3044篇 |
武器工业 | 279篇 |
无线电 | 3457篇 |
一般工业技术 | 1622篇 |
冶金工业 | 525篇 |
原子能技术 | 211篇 |
自动化技术 | 6950篇 |
出版年
2024年 | 114篇 |
2023年 | 279篇 |
2022年 | 558篇 |
2021年 | 650篇 |
2020年 | 714篇 |
2019年 | 564篇 |
2018年 | 527篇 |
2017年 | 690篇 |
2016年 | 886篇 |
2015年 | 1001篇 |
2014年 | 2014篇 |
2013年 | 1615篇 |
2012年 | 2619篇 |
2011年 | 2799篇 |
2010年 | 2133篇 |
2009年 | 2280篇 |
2008年 | 2096篇 |
2007年 | 2510篇 |
2006年 | 2336篇 |
2005年 | 1663篇 |
2004年 | 1373篇 |
2003年 | 1089篇 |
2002年 | 798篇 |
2001年 | 656篇 |
2000年 | 548篇 |
1999年 | 438篇 |
1998年 | 309篇 |
1997年 | 273篇 |
1996年 | 222篇 |
1995年 | 167篇 |
1994年 | 121篇 |
1993年 | 65篇 |
1992年 | 65篇 |
1991年 | 37篇 |
1990年 | 27篇 |
1989年 | 34篇 |
1988年 | 17篇 |
1987年 | 10篇 |
1986年 | 10篇 |
1985年 | 9篇 |
1984年 | 11篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1965年 | 1篇 |
1960年 | 1篇 |
1959年 | 1篇 |
1957年 | 2篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
航空多芯电缆检测系统设计 总被引:2,自引:0,他引:2
介绍了航空多芯电缆通断测试、耐压绝缘阻值测量和漏电故障检测的原理和方法,并采用凌阳SPCE061A单片机和CPLD系统相结合,设计出一种实现对航空多芯电缆进行准确、高效、便捷测量的系统.该系统可快速对航空多芯电缆进行离线检测,准确测量电缆的通断、耐压绝缘阻值和电缆漏电点距离, 并实时显示测试结果.系统具有操作简单,运行可靠,测试精度高等特点.设计完成后经调试与运行,系统工作效果良好,并能准确实现各项电缆测试. 相似文献
33.
基于多信息融合技术的智能汽车防盗报警系统研究与设计 总被引:2,自引:0,他引:2
为完善汽车的防盗系统,提出研制的智能汽车防盗报警器是在ARM嵌入式系统的基础上,利用Dempster--Sharer证据理论融合密码识别、加速度传感、GPS全球定位信息,判断车辆的安全状况,再将车况信息通过GPRS无线通信网络发送到车主手机。实验室测试表明,系统实现了监控基本功能并满足实时性,增强了汽车安全性和智能报警性。 相似文献
34.
文中基于热叠加原理研究了固态功率组件中多个离散分布的集中热源的热耦合效应,并证明强迫对流下应用热叠加原理计算的温度场与整场系统数值模拟的结果相当吻合,用它来进行热耦合效应的分析研究是有效的. 相似文献
35.
As a representative deep learning network, Convolutional Neural Network (CNN) has been extensively used in bearing fault diagnosis and many good results have been reported. In Prognostics and Health Management (PHM) field, the CNN’s input size is usually designed as a 1D vector or 2D square matrix, and the convolution kernel size is also defined as a square shape like 3 × 3 and 5 × 5, which are directly adopted from the image recognition. Though satisfying results can be obtained, CNN with such parameter specifications is not optimal and efficient. To this end, this paper elaborated the physical characteristics of bearing acceleration signals to guide the CNN design. First, the fault period under different fault types and shaft rotation frequency were used to determine the size of CNN’s input. Next, an exponential function was involved in fitting the envelope of decaying acceleration signal during each fault period, and signal length within different decaying ratios was used to define the CNN’s kernel size. Finally, the designed CNN was validated with the Case Western Reserve University bearing dataset and Paderborn University bearing dataset. Results confirm that the physics-guided CNN (PGCNN) with rectangular input shape and rectangular convolution kernel works better than the baseline CNN with higher accuracy and smaller uncertainty. The feasibility of designing CNN parameters with physics-guided rules derived from bearing fault signal analysis has also been verified. 相似文献
36.
The more advanced multi-view extension, MV-HEVC, effectively exploits visual similarities between multi-view videos and enables high compression efficiency. Each view in the multi-view sequence depends on the captured scene, the distance between cameras and recording angles. Increasing the distance between dependent viewpoints generates an inter-view disparity. This impacts the inter-view similarities, affects the disparity estimation and further increases the computational complexity of the MV-HEVC encoder. In this paper, an efficient earlier disparity estimation is proposed for low complexity MV-HEVC. This algorithm is based on reducing the complexity of disparity estimation by eliminating the inter-view offset. Moreover, the inter-view similarities are controlled by considering the reliability of each coding unit size in the search range. This reliability is estimated by reducing the number of searching points within a new limited window. For reliable motion estimation, we further proposed an earlier decision of coding units splitting in the dependent views according to those in the reference views. Experimental results show that the proposed algorithm can achieve an average encoding time saving of 20.37%–40,61% with marginal performance degradation. 相似文献
37.
Gregory Gutin Eun Jung Kim Matthias Mnich Anders Yeo 《Journal of Computer and System Sciences》2010,76(8):872-878
We study ordinal embedding relaxations in the realm of parameterized complexity. We prove the existence of a quadratic kernel for the Betweenness problem parameterized above its tight lower bound, which is stated as follows. For a set V of variables and set C of constraints “vi is between vj and vk”, decide whether there is a bijection from V to the set {1,…,|V|} satisfying at least |C|/3+κ of the constraints in C. Our result solves an open problem attributed to Benny Chor in Niedermeier's monograph “Invitation to Fixed-Parameter Algorithms”. The betweenness problem is of interest in molecular biology. An approach developed in this paper can be used to determine parameterized complexity of a number of other optimization problems on permutations parameterized above or below tight bounds. 相似文献
38.
栾新源 《单片机与嵌入式系统应用》2011,11(5):21-24
用FPGA+ARM的方式设计低成本加固液晶显示器控制电路.FPGA负责对比度调整,ARM微控制器负责温度、亮度、通信、键盘扫描的控制.创新之处在于用低成本架构取代老方案,缩短开发周期,并引入LED背光源辅助加热、动态背光源降低功耗的思想. 相似文献
39.
The centroid-based classifier is both effective and efficient for document classification. However, it suffers from over-fitting and linear inseparability problems caused by its fundamental assumptions. To address these problems, we propose a kernel-based hypothesis margin centroid classifier (KHCC). First, KHCC optimises the class centroids via minimising hypothesis margin under structural risk minimisation principle; second, KHCC uses the kernel method to relieve the problem of linear inseparability in the original feature space. Given the radial basis function, we further discuss a guideline for tuning the value of its parameter. The experimental results on four well-known data-sets indicate that our KHCC algorithm outperforms the state-of-the-art algorithms, especially for the unbalanced data-set. 相似文献
40.
This paper proposes a probabilistic variant of the SOM-kMER (Self Organising Map-kernel-based Maximum Entropy learning Rule)
model for data classification. The classifier, known as pSOM-kMER (probabilistic SOM-kMER), is able to operate in a probabilistic
environment and to implement the principles of statistical decision theory in undertaking classification problems. A distinctive
feature of pSOM-kMER is its ability in revealing the underlying structure of data. In addition, the Receptive Field (RF) regions
generated can be used for variable kernel and non-parametric density estimation. Empirical evaluation using benchmark datasets
shows that pSOM-kMER is able to achieve good performance as compared with those from a number of machine learning systems.
The applicability of the proposed model as a useful data classifier is also demonstrated with a real-world medical data classification
problem. 相似文献