全文获取类型
收费全文 | 706176篇 |
免费 | 9204篇 |
国内免费 | 2106篇 |
专业分类
电工技术 | 13022篇 |
综合类 | 675篇 |
化学工业 | 105768篇 |
金属工艺 | 26766篇 |
机械仪表 | 20492篇 |
建筑科学 | 17449篇 |
矿业工程 | 2964篇 |
能源动力 | 19848篇 |
轻工业 | 61492篇 |
水利工程 | 6817篇 |
石油天然气 | 11422篇 |
武器工业 | 45篇 |
无线电 | 83528篇 |
一般工业技术 | 137459篇 |
冶金工业 | 136851篇 |
原子能技术 | 13897篇 |
自动化技术 | 58991篇 |
出版年
2022年 | 4182篇 |
2021年 | 6408篇 |
2020年 | 4672篇 |
2019年 | 5912篇 |
2018年 | 10067篇 |
2017年 | 9875篇 |
2016年 | 10398篇 |
2015年 | 7135篇 |
2014年 | 11963篇 |
2013年 | 32730篇 |
2012年 | 18904篇 |
2011年 | 26156篇 |
2010年 | 20695篇 |
2009年 | 23364篇 |
2008年 | 23991篇 |
2007年 | 23570篇 |
2006年 | 20714篇 |
2005年 | 18637篇 |
2004年 | 18011篇 |
2003年 | 17890篇 |
2002年 | 16925篇 |
2001年 | 17303篇 |
2000年 | 16034篇 |
1999年 | 17010篇 |
1998年 | 43470篇 |
1997年 | 30441篇 |
1996年 | 23372篇 |
1995年 | 17614篇 |
1994年 | 15394篇 |
1993年 | 15176篇 |
1992年 | 10935篇 |
1991年 | 10377篇 |
1990年 | 10127篇 |
1989年 | 9706篇 |
1988年 | 9139篇 |
1987年 | 8048篇 |
1986年 | 7896篇 |
1985年 | 8751篇 |
1984年 | 8162篇 |
1983年 | 7413篇 |
1982年 | 6945篇 |
1981年 | 6919篇 |
1980年 | 6657篇 |
1979年 | 6404篇 |
1978年 | 6066篇 |
1977年 | 7367篇 |
1976年 | 9759篇 |
1975年 | 5177篇 |
1974年 | 4935篇 |
1973年 | 4955篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
The theory of characteristic modes for aperture problems is used in this paper to solve the equivalent magnetic current and aperture fields due to a conducting cylinder with multiple slots. It is assumed that these slots are illuminated by either a transverse electric (TE) or a transverse magnetic (TM) plane wave and the media inside and outside the cylinder exhibit different electromagnetic properties. The formulation is given for the general case and numerical results for a limited number of slots are presented 相似文献
132.
Mine K. Kubota N. Morimoto F. Sanada M. Zhang Qi 《Electromagnetic Compatibility, IEEE Transactions on》1994,36(3):253-255
This short paper discusses the method of effectively canceling equal status normal mode noise not only on a sensor line but also on a transmission line of an optical instrument using a sensor with a sensordummy resistance 相似文献
133.
Crosstalk between microstrip transmission lines 总被引:1,自引:0,他引:1
Hill D.A. Cavcey K.H. Johnk R.T. 《Electromagnetic Compatibility, IEEE Transactions on》1994,36(4):314-321
Methods for prediction of crosstalk between microstrip transmission lines are reviewed and simplified for the weak-coupling case. Classical coupled transmission line theory is used for uniform lines, and potential and induced EMF methods are used for crosstalk between nonuniform lines. It is shown that the potential method is equivalent to classical coupled transmission line theory for the case of uniform lines. An experiment was performed for uniform coupled microstrip lines for frequencies from 50 MHz to 5 GHz, and good agreement between theory and measurement was obtained for both near- and far-end crosstalk 相似文献
134.
135.
An instrument is proposed for continuously tracking the Sun and measuring its height by the use of a laser gyrometer as measuring
converter. The accuracy in photoelectric sighting on the Sun is improved by greatly reducing the light fluxes to be compared
by screening out the central part of the Sun's image in the focal plane.
Translated from Izmeritel'naya Tekhnika, No. 3, pp. 7–9, March, 1994. 相似文献
136.
A.S. Fomichev I. David S.M. Lukyanov Yu.E. Penionzhkevich N.K. Skobelev O.B. Tarasov 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1994,350(3):605-607
The mass and charge identification of secondary particles with Z < 4 by a large CsI(T1) scintillation detector is performed using pulse shape analysis and time-of-flight methods. The dependence of the light output on E, A and Z is studied in the energy range of 1–20 MeV/A and special attention is paid to the integration time of the photomultiplier anode signal. It is found that the behaviour of the calibration curves strongly depends on the choice of the integration time interval. 相似文献
137.
138.
This paper proposes a method to reduce the vibration of the three-phase HB-type stepping motor with cogging torque by the feedforward compensation control. The compensation signal to suppress the vibration of the motor frame is obtained by the repetitive controller installing an online Fourier transformer and utilizing an acceleration sensor attached to the motor frame or an acoustic sensor such as a microphone placed close to the frame. The sensor is used only for the acquisition of the feedforward compensation data. The feedforward compensation signal at an arbitrary operating point is derived from the amplitude and phase data of the frequency components and the operating point data. Compensation data obtained by the repetitive controller is applied to the operating point changed by reference frequency and load condition in steady state. The compensation signal for the new operating point will be generated from compensation data utilizing polynomial equation approximation and linear interpolation method. The effectiveness of this proposed method is confirmed by the experimental results. 相似文献
139.
LJ Huang K Durick JA Weiner J Chun SS Taylor 《Canadian Metallurgical Quarterly》1997,94(21):11184-11189
Subcellular localization directed by specific A kinase anchoring proteins (AKAPs) is a mechanism for compartmentalization of cAMP-dependent protein kinase (PKA). Using a two-hybrid screen, a novel AKAP was isolated. Because it interacts with both the type I and type II regulatory subunits, it was defined as a dual specific AKAP or D-AKAP1. Here we report the cloning and characterization of another novel cDNA isolated from that screen. This new member of the D-AKAP family, D-AKAP2, also binds both types of regulatory subunits. A message of 5 kb pairs was detected for D-AKAP2 in all embryonic stages and in all adult tissues tested. In brain, skeletal muscle, kidney, and testis, a 10-kb mRNA was identified. In testis, several small mRNAs were observed. Therefore, D-AKAP2 represents a novel family of proteins. cDNA cloning from a mouse testis library identified the full length D-AKAP2. It is composed of 372 amino acids which includes the R binding fragment, residues 333-372, at its C-terminus. Based on coprecipitation assays, the R binding domain interacts with the N-terminal dimerization domain of RIalpha and RIIalpha. A putative RGS domain was identified near the N-terminal region of D-AKAP2. The presence of this domain raises the intriguing possibility that D-AKAP2 may interact with a Galpha protein thus providing a link between the signaling machinery at the plasma membrane and the downstream kinase. 相似文献
140.
Presents the Satellite Communications Network Expert (SaNE), a knowledge-based aid designed to provide engineering support for fault diagnosis. The SaNE is composed of two elements: a satcom network model, which simulates the structure and functionality of a system based loosely upon a large military satcom network, and a diagnostic component, which uses knowledge- and model-based reasoning techniques to analyse system anomalies and diagnose possible causes for the alarms such networks generate. The development cycle is described, emphasising lessons learnt during development and testing and the advantages and disadvantages of the techniques applied. The goal of the SaNE project is primarily commercial acceptance rather than innovation. The authors illustrate how novel concepts can be implemented in a practical system without compromising this goal 相似文献