全文获取类型
收费全文 | 23746篇 |
免费 | 2990篇 |
国内免费 | 1253篇 |
专业分类
电工技术 | 3545篇 |
技术理论 | 1篇 |
综合类 | 2623篇 |
化学工业 | 765篇 |
金属工艺 | 492篇 |
机械仪表 | 2030篇 |
建筑科学 | 183篇 |
矿业工程 | 435篇 |
能源动力 | 223篇 |
轻工业 | 290篇 |
水利工程 | 107篇 |
石油天然气 | 594篇 |
武器工业 | 596篇 |
无线电 | 8627篇 |
一般工业技术 | 1536篇 |
冶金工业 | 342篇 |
原子能技术 | 194篇 |
自动化技术 | 5406篇 |
出版年
2024年 | 118篇 |
2023年 | 316篇 |
2022年 | 544篇 |
2021年 | 593篇 |
2020年 | 669篇 |
2019年 | 492篇 |
2018年 | 526篇 |
2017年 | 783篇 |
2016年 | 871篇 |
2015年 | 1091篇 |
2014年 | 1551篇 |
2013年 | 1402篇 |
2012年 | 1915篇 |
2011年 | 1953篇 |
2010年 | 1483篇 |
2009年 | 1378篇 |
2008年 | 1506篇 |
2007年 | 1944篇 |
2006年 | 1616篇 |
2005年 | 1405篇 |
2004年 | 1106篇 |
2003年 | 889篇 |
2002年 | 686篇 |
2001年 | 625篇 |
2000年 | 497篇 |
1999年 | 420篇 |
1998年 | 292篇 |
1997年 | 277篇 |
1996年 | 200篇 |
1995年 | 164篇 |
1994年 | 147篇 |
1993年 | 139篇 |
1992年 | 77篇 |
1991年 | 62篇 |
1990年 | 52篇 |
1989年 | 47篇 |
1988年 | 32篇 |
1987年 | 21篇 |
1986年 | 10篇 |
1985年 | 19篇 |
1984年 | 6篇 |
1983年 | 14篇 |
1982年 | 8篇 |
1981年 | 10篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1963年 | 4篇 |
1962年 | 2篇 |
1959年 | 4篇 |
1957年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
应用卫星导航、软件无线电、计算机控制、电磁兼容等技术,研制了基于"工控机+DSP+FPGA"架构的多模卫星信号模拟器;该模拟器在国内最先实现了GPS、GLONASS和北斗一号信号的任意组合、时空同步仿真;详细论述了模拟器硬件方案,介绍了其软件构成和各模块功能,最后通过成熟商业多模接收机验证了模拟器所仿真信号的有效性和任意时空性;此外,该模拟器无需更改硬件即可在未来向北斗二号系统扩展。 相似文献
82.
使用市场上成熟的模块和技术研制机载塔康设备综合检查仪,以降低成本和提高设备的可靠性;根据设备的测试需求,选用嵌入式工业平板电脑、USB-ARINC429通讯卡、USB-数字IO卡、串行接口数字表和自研的塔康信号模拟器等构成检查仪硬件,使用CVI9.0编写了测试程序;应用表明:检查仪集成度高,使用方便,能够完成对塔康设备的自动及手动测试。 相似文献
83.
Tianqi ZhangAuthor Vitae Shaosheng DaiAuthor VitaeWei ZhangAuthor Vitae Guoning MaAuthor VitaeXiangyun GaoAuthor Vitae 《Digital Signal Processing》2012,22(1):106-113
This paper presents a method of singular value decomposition (SVD) plus digital phase lock loop (DPLL) to solve the difficult problem of blind pseudo-noise (PN) sequence estimation in low signal to noise ratios (SNR) direct sequence spread spectrum (DS-SS, DS) signals with residual carrier. Of course, the method needs to know the parameters of DS signal, such as the period and code rate of PN sequence. Firstly, the received signal is sampled and divided into non-overlapping signal vectors according to a temporal window, whose duration is two periods of PN sequence. Then, an autocorrelation matrix is computed and accumulated by the signal vectors one by one. The PN sequence with residual carrier can be estimated by the principal eigenvector of this autocorrelation matrix. Furthermore, a DPLL is used to deal with the estimated PN sequence with residual carrier, it estimates and tracks the residual carrier, removes the residual carrier in the end. Theory analysis and computer simulation results show that this method can effectively realize the PN sequence estimation from the input DS signals with residual carrier in lower SNR. 相似文献
84.
To overcome the disadvantages of the location algorithm based on received signal strength indication(RSSI) in the existing wireless sensor networks(WSNs),a novel adaptive cooperative location algorithm is proposed.To tolerate some minor errors in the information of node position,a reference anchor node is employed.On the other hand,Dixon method is used to remove the outliers of RSSI,the standard deviation threshold of RSSI and the learning model are put forward to reduce the ranging error of RSSI and improve the positioning precision effectively.Simulations are run to evaluate the performance of the algorithm.The results show that the proposed algorithm offers more precise location and better stability and robustness. 相似文献
85.
Nasir A. Al-geelani M. Afendi M. PiahRedhwan Q. Shaddad 《Applied Soft Computing》2012,12(4):1239-1246
A hybrid model incorporating wavelet and radial basis function neural network is presented which is used to detect, identify and characterize the acoustic signals due to surface discharge activity and hence differentiate abnormal operating conditions from the normal ones. The tests were carried out on cleaned and polluted high voltage glass insulators by using surface tracking and erosion test procedure of international electrotechnical commission 60587. A laboratory experiment was conducted by preparing the prototypes of the discharges. This study suggests a feature extraction and classification algorithm for surface discharge classification, which when combined together reduced the dimensionality of the feature space to a manageable dimension, by “marrying” the wavelet to radial basis function neural network very high levels of classification are achieved. Wavelet signal treatment toolbox is used to recover the surface discharge acoustic signals by eliminating the noisy portion and to reduce the dimension of the feature input vector. A radial basis function neural network classifier was used to classify the surface discharge and assess the suitability of this feature vector in classification. This learning method is proved to be effective by applying the wavelet radial basis function neural network in the classification of surface discharge fault data set. The test results show that the proposed approach is efficient and reliable. 相似文献
86.
The Constraint Logic Programming Scheme defines a class of languages designed for programming with constraints using a logic programming approach. These languages are soundly based on a unified framework of formal semantics. In particular, as an instance of this scheme with real arithmetic constraints, the CLP() language facilitates and encourages a concise and declarative style of programming for problems involving a mix of numeric and non-numeric computation.In this paper we illustrate the practical applicability of CLP() with examples of programs to solve electrical engineering problems. This field is particularly rich in problems that are complex and largely numeric, enabling us to demonstrate a number of the unique features of CLP(). A detailed look at some of the more important programming techniques highlights the ability of CLP() to support well-known, powerful techniques from constraint programming. Our thesis is that CLP() is an embodiment of these techniques in a language that is more general, elegant and versatile than the earlier languages, and yet is practical.An earlier version of this paper appeared in the proceedings of the 4th International Conference on Logic Programming, Melbourne, May 1987. Much of this work was carried out while the authors were at Monash University, Melbourne, Australia. 相似文献
87.
88.
89.
为提高舌控智能辅助系统舌部运动信息的采集精度,利用STM32H743和LabVIEW设计了一种对舌机接口辅助系统进行信号采集、传输的通信装置.该装置通过舌部触碰嵌入式电极传感器发出信号并传输给单片机(进行舌控信号采集),然后通过串口传给上位机以此最终实现数据的采集与保存.实验结果表明,该装置可有效完成舌控智能辅助系统对控制信号的采集与传输,并具有实时显示、自动保存和查询历史数据等功能; 因此,该装置在舌控智能辅助系统的信号采集中具有良好的应用前景. 相似文献
90.
为了有效地降低数字信号传输过程中的比特误码率,提出了纠错编码与参数调节随机共振技术的结合.在经过噪声污染后,依据参数调节随机共振技术的性质,给出通过系统参数调节的二进制脉冲幅值调制(PAM)输入信号的渐近误码率公式,应用纠错码技术采用中间值估计的方法得到修正的比特误码率.数字仿真试验证实,理论计算结果与试验结果相吻合,纠错码技术与参激随机共振技术的结合应用于二进制基带信号传输,可以降低误码率,从而可以得到更好的效果,提高通信的可靠性和有效性. 相似文献