全文获取类型
收费全文 | 327391篇 |
免费 | 2908篇 |
国内免费 | 1452篇 |
专业分类
电工技术 | 5729篇 |
综合类 | 337篇 |
化学工业 | 44319篇 |
金属工艺 | 20458篇 |
机械仪表 | 13014篇 |
建筑科学 | 6177篇 |
矿业工程 | 2638篇 |
能源动力 | 6125篇 |
轻工业 | 15666篇 |
水利工程 | 4314篇 |
石油天然气 | 10247篇 |
武器工业 | 27篇 |
无线电 | 35083篇 |
一般工业技术 | 74962篇 |
冶金工业 | 55983篇 |
原子能技术 | 8992篇 |
自动化技术 | 27680篇 |
出版年
2021年 | 2196篇 |
2019年 | 2203篇 |
2018年 | 11142篇 |
2017年 | 11623篇 |
2016年 | 8598篇 |
2015年 | 3026篇 |
2014年 | 4439篇 |
2013年 | 10838篇 |
2012年 | 8906篇 |
2011年 | 15969篇 |
2010年 | 14149篇 |
2009年 | 14079篇 |
2008年 | 14251篇 |
2007年 | 16093篇 |
2006年 | 7667篇 |
2005年 | 9760篇 |
2004年 | 8317篇 |
2003年 | 7802篇 |
2002年 | 6544篇 |
2001年 | 6356篇 |
2000年 | 6037篇 |
1999年 | 6133篇 |
1998年 | 15757篇 |
1997年 | 10894篇 |
1996年 | 8296篇 |
1995年 | 5887篇 |
1994年 | 5258篇 |
1993年 | 5309篇 |
1992年 | 3819篇 |
1991年 | 3854篇 |
1990年 | 3851篇 |
1989年 | 3559篇 |
1988年 | 3436篇 |
1987年 | 3008篇 |
1986年 | 3082篇 |
1985年 | 3176篇 |
1984年 | 2984篇 |
1983年 | 2800篇 |
1982年 | 2648篇 |
1981年 | 2835篇 |
1980年 | 2597篇 |
1979年 | 2718篇 |
1978年 | 2821篇 |
1977年 | 2938篇 |
1976年 | 4009篇 |
1975年 | 2533篇 |
1974年 | 2574篇 |
1973年 | 2587篇 |
1972年 | 2332篇 |
1971年 | 2042篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Baldridge K.K. Greenberg J.P. Sudholt W. Mock S. Altintas I. Amoreira C. Potier Y. Birnbaum A. Bhatia K. Taufer M. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2005,93(3):510-521
Evolving technologies, as exemplified by computational grids and Web services, have made it possible to solve new scientific problems that would not have been feasible previously. In order to make such advances available to the community in general and to be able to solve new problems, not necessarily from the same discipline, it is imperative to build tools that provide a common user interface in order that application programmers and users do not have to be concerned with particulars of Web services and their underlying code, computational platforms, or with data file formats. We will describe our efforts in creating a computational chemistry environment that encompasses a general scientific workflow environment, a domain specific example for quantum chemistry, our ongoing design of a workflow user interface, and our efforts at database integration. 相似文献
992.
A. V. Solokhin S. L. Nazanskii V. S. Timofeev 《Theoretical Foundations of Chemical Engineering》2005,39(2):105-109
The evolution of the phase portrait for the dynamic system of open evaporation combined with a chemical reaction for a fixed liquid amount was studied as dependent on the rate constants of the reaction. A three-component azeotropic mixture whose vapor-liquid equilibrium diagram is characterized by two distillation regions was considered. The possibility of the open evaporation trajectory to transfer through the separatrix between the distillation regions was shown, as well as the possibility of implementing the principle of redistribution of the concentration fields due to chemical reactions occurring in reactive distillation columns.Translated from Teoreticheskie Osnovy Khimicheskoi Tekhnologii, Vol. 39, No. 2, 2005, pp. 115–119.Original Russian Text Copyright © 2005 by Solokhin, Nazanskii, Timofeev. 相似文献
993.
Ohne Zusammenfassung 相似文献
994.
A temperature sensor using a fiber-optic Fabry-Perot interferometer is described. A pseudo-heterodyne detection scheme is adopted to read the light phase difference in the Fabry-Perot interference output. A higher harmonic components comparison method is used to stabilize the system and to increase detection linearity. This system realizes not only highly sensitive temperature sensing with good linearity and minimal adjusting error, but also application to the sensing of other physical quantities such as vibrations. Additionally, the signal-to-noise ratio and distortion of the detected signal are investigated as functions of fiber end reflectivity. These results will be useful in designing a high performance fiber-optic Fabry-Perot thermometer. 相似文献
995.
996.
Z. P. Shul'man B. M. Khusid I. L. Ryklina É. A. Zal'tsgendler O. R. Dornyak É. V. Ivashkevich Z. A. Shabunina 《Journal of Engineering Physics and Thermophysics》1987,53(5):1285-1291
Dynamic processes are studied in media with softly and hardly internal destroyable configurations. A method is examined for the measurement of properties of media with spatial separation of the chemical transformation stages and thermal hydrodynamic measurements.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 53, No. 5, pp. 781–789, November, 1987. 相似文献
997.
998.
Automated camerawork for capturing desktop presentations 总被引:1,自引:0,他引:1
Ozeki M. Nakamura Y. Ohta Y. 《Vision, Image and Signal Processing, IEE Proceedings -》2005,152(4):437-447
A novel automated camera control method for capturing desktop presentations is introduced. Typical features and the camerawork of shots that appear frequently in TV programs are discussed. To realise those features in this automated video capturing system, the purpose of camerawork is classified from two points of view: target and aspect-of-target. Then, the correspondence between the classification and typical shots and camerawork is considered. A virtual-frame control algorithm based on this idea is proposed, and its implementation in a video production system. Results are shown that verify this method through two kinds of experiments, virtual video capturing using CG animations and real video capturing of real presentations. 相似文献
999.
Y. Rey-Tauriac J. Badoc B. Reynard R.A. Bianchi D. Lachenal A. Bravaix 《Microelectronics Reliability》2005,45(9-11):1349
This paper presents results of reliability investigation of 20 V N-Drift MOS transistor in 0.13 μm CMOS technology. Due to high performances required for CMOS applications, adding high voltage devices becomes a big challenge to guarantee the reliability criteria. In this context, new reliability approaches are needed. Safe Operating Area are defined for switch, Vds limited and Vgs limited applications in order to improve circuit designs. For Vds limited applications, deep doping dose effects in drift area are investigated in correlation to lifetime evaluations based on device parameter shifts under hot carrier stressing. To further determine the amount and locations of hot carriers injections, accurate 2D technological and electrical simulations are performed and permit to select the best compromise between performance and reliability for N-Drift MOS transistor. 相似文献
1000.
N. V. Vostokov Yu. N. Drozdov Z. F. Krasil’nik O. A. Kuznetsov A. V. Novikov V. A. Perevoshchikov M. V. Shaleev 《Russian Microelectronics》2005,34(4):203-209
The results are presented of the fabrication of strain-relaxed graded Si1 − x
Gex/Si(001) buffer layers with a maximum Ge fraction of about 0.25 that have a low density of threading dislocations (<106 cm−2) and low surface roughness. The buffer layers are grown by atmospheric-pressure hydride CVD. It is found that chemical mechanical polishing can reduce their surface roughness to a level comparable with that of the original Si(001) substrates. It is shown that the polished buffer layers can serve as substrates for MBE-grown SiGe/Si heterostructures.__________Translated from Mikroelektronika, Vol. 34, No. 4, 2005, pp. 243–250.Original Russian Text Copyright © 2005 by Vostokov, Drozdov, Krasil’nik, Kuznetsov, Novikov, Perevoshchikov, Shaleev. 相似文献