全文获取类型
收费全文 | 4603篇 |
免费 | 121篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 124篇 |
综合类 | 8篇 |
化学工业 | 1085篇 |
金属工艺 | 90篇 |
机械仪表 | 95篇 |
建筑科学 | 285篇 |
矿业工程 | 20篇 |
能源动力 | 107篇 |
轻工业 | 485篇 |
水利工程 | 57篇 |
石油天然气 | 11篇 |
无线电 | 325篇 |
一般工业技术 | 597篇 |
冶金工业 | 857篇 |
原子能技术 | 77篇 |
自动化技术 | 507篇 |
出版年
2022年 | 45篇 |
2021年 | 72篇 |
2020年 | 46篇 |
2019年 | 57篇 |
2018年 | 47篇 |
2017年 | 55篇 |
2016年 | 66篇 |
2015年 | 74篇 |
2014年 | 102篇 |
2013年 | 196篇 |
2012年 | 140篇 |
2011年 | 218篇 |
2010年 | 136篇 |
2009年 | 142篇 |
2008年 | 173篇 |
2007年 | 145篇 |
2006年 | 153篇 |
2005年 | 117篇 |
2004年 | 108篇 |
2003年 | 100篇 |
2002年 | 104篇 |
2001年 | 68篇 |
2000年 | 66篇 |
1999年 | 82篇 |
1998年 | 148篇 |
1997年 | 119篇 |
1996年 | 90篇 |
1995年 | 86篇 |
1994年 | 74篇 |
1993年 | 64篇 |
1992年 | 51篇 |
1991年 | 50篇 |
1990年 | 63篇 |
1989年 | 59篇 |
1988年 | 52篇 |
1987年 | 59篇 |
1986年 | 51篇 |
1985年 | 66篇 |
1984年 | 61篇 |
1983年 | 63篇 |
1982年 | 54篇 |
1981年 | 44篇 |
1979年 | 49篇 |
1978年 | 60篇 |
1977年 | 61篇 |
1976年 | 71篇 |
1975年 | 55篇 |
1974年 | 52篇 |
1973年 | 59篇 |
1972年 | 43篇 |
排序方式: 共有4730条查询结果,搜索用时 15 毫秒
81.
Walter J. Thomas Mohamed A. El-Sawy Edward W. Palmer 《Chemical Engineering Communications》1982,16(1):53-78
Two published theoretical models are examined and applied to experimental results for absorption and desorption. The system used was CO2/H2O and studies were made for liquid film flow down inclined planes. Experimental results give “Reduced” values of mass ransfer rates.
Interferometric studies give interfacial concentration, penetration and film depths, and take-up of carbon dioxide. In the case of desorption the interferograms are distorted by “deflections.”
All the experimental values for absorption and desorption differ from those calculated from theoretical models.
Desorption is not a mirror image of absorption, and it is approximately 75% of the transfer rate of absorption over a wide operating range.
A comparison is made of the behaviour of static pools and flowing liquid films. 相似文献
Interferometric studies give interfacial concentration, penetration and film depths, and take-up of carbon dioxide. In the case of desorption the interferograms are distorted by “deflections.”
All the experimental values for absorption and desorption differ from those calculated from theoretical models.
Desorption is not a mirror image of absorption, and it is approximately 75% of the transfer rate of absorption over a wide operating range.
A comparison is made of the behaviour of static pools and flowing liquid films. 相似文献
82.
83.
We present a model of spatial navigation based on the non-convergent dynamics of brain activity. The system includes a hippocampal module that processes global spatial information and a cortical module that deals with local sensory information. We test the model using several spatial navigation paradigms: goal finding, shortcutting and detouring. Computer simulations show that the performance of the agent qualitatively matches that of animals and related models. This new approach provides a novel interpretation of how the brain accomplishes spatial navigation. 相似文献
84.
85.
86.
87.
Barton B Rhinow D Walter A Schröder R Benner G Majorovits E Matijevic M Niebel H Müller H Haider M Lacher M Schmitz S Holik P Kühlbrandt W 《Ultramicroscopy》2011,111(12):1696-1705
We report the implementation of an electrostatic Einzel lens (Boersch) phase plate in a prototype transmission electron microscope dedicated to aberration-corrected cryo-EM. The combination of phase plate, Cs corrector and Diffraction Magnification Unit (DMU) as a new electron-optical element ensures minimal information loss due to obstruction by the phase plate and enables in-focus phase contrast imaging of large macromolecular assemblies. As no defocussing is necessary and the spherical aberration is corrected, maximal, non-oscillating phase contrast transfer can be achieved up to the information limit of the instrument. A microchip produced by a scalable micro-fabrication process has 10 phase plates, which are positioned in a conjugate, magnified diffraction plane generated by the DMU. Phase plates remained fully functional for weeks or months. The large distance between phase plate and the cryo sample permits the use of an effective anti-contaminator, resulting in ice contamination rates of <0.6 nm/h at the specimen. Maximal in-focus phase contrast was obtained by applying voltages between 80 and 700 mV to the phase plate electrode. The phase plate allows for in-focus imaging of biological objects with a signal-to-noise of 5-10 at a resolution of 2-3 nm, as demonstrated for frozen-hydrated virus particles and purple membrane at liquid-nitrogen temperature. 相似文献
88.
Andrea Bettidi Antonio Cetronio Walter Ciccognani Marco De Dominicis Claudio Lanzieri Ernesto Limiti Antonio Manna Marco Peroni Claudio Proietti Paolo Romanini 《国际射频与微波计算机辅助工程杂志》2009,19(5):598-606
In this article, the design, fabrication, and on‐wafer test of X‐Band and 2–18 GHz wideband high‐power SPDT MMIC switches in AlGaN/GaN technology are presented. The switches have demonstrated state‐of‐the‐art performance and RF fabrication yield better than 65%. Linear and power measurements for different control voltages have been reported and an explanation of the dependence of the power performances on the control voltage is given. In particular, the X‐band switch exhibits a 0.4 dB compression level at 10 GHz when driven by a 38 dBm input signal. The wideband switch shows a compression level of 1 dB at an input drive higher than 38 dBm across the entire bandwidth. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009. 相似文献
89.
In a paper recently published (ibid., vol.12, p. 30-8, 1993), Chiang and Sullivan compare a new criterion for image registration called CBC (coincident bit counting) with two criteria that the authors proposed some years ago, namely SSC and DSC (stochastic and deterministic sign change criteria). The authors' nonparametric approach was demonstrated to outperform the conventional image registration criteria for robust registration in the fact that the value of their similarity measure did not take the specific pixel values into account. In light of this observation, Chiang and Sullivan have built the CBC criterion. The CBC method compares the number of coincident bits between the corresponding pixels in two different frames for a fixed amount of displacement. While the authors consider that the CBC is of interest and deserves to be studied, they feel that the comparison made by Chiang and Sullivan was not entirely accurate. Here the authors comment on this comparison and suggest possible further studies. 相似文献
90.
Discusses the evolution of the Psychological Review from its inception in 1894 as a general journal to its current status as a forum for theoretical discussion. A historical overview of Psychological Review is presented, and its 2 main subfields, cognition and perception, are outlined. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献