全文获取类型
收费全文 | 3240篇 |
免费 | 56篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 152篇 |
综合类 | 5篇 |
化学工业 | 679篇 |
金属工艺 | 97篇 |
机械仪表 | 74篇 |
建筑科学 | 56篇 |
能源动力 | 81篇 |
轻工业 | 211篇 |
水利工程 | 19篇 |
石油天然气 | 2篇 |
无线电 | 366篇 |
一般工业技术 | 551篇 |
冶金工业 | 712篇 |
原子能技术 | 65篇 |
自动化技术 | 238篇 |
出版年
2022年 | 23篇 |
2021年 | 43篇 |
2020年 | 24篇 |
2019年 | 22篇 |
2018年 | 41篇 |
2017年 | 37篇 |
2016年 | 53篇 |
2015年 | 41篇 |
2014年 | 49篇 |
2013年 | 136篇 |
2012年 | 90篇 |
2011年 | 152篇 |
2010年 | 116篇 |
2009年 | 116篇 |
2008年 | 117篇 |
2007年 | 122篇 |
2006年 | 94篇 |
2005年 | 96篇 |
2004年 | 106篇 |
2003年 | 87篇 |
2002年 | 74篇 |
2001年 | 60篇 |
2000年 | 51篇 |
1999年 | 81篇 |
1998年 | 302篇 |
1997年 | 178篇 |
1996年 | 150篇 |
1995年 | 81篇 |
1994年 | 61篇 |
1993年 | 98篇 |
1992年 | 42篇 |
1991年 | 51篇 |
1990年 | 34篇 |
1989年 | 38篇 |
1988年 | 36篇 |
1987年 | 28篇 |
1986年 | 49篇 |
1985年 | 41篇 |
1984年 | 37篇 |
1983年 | 33篇 |
1982年 | 29篇 |
1981年 | 32篇 |
1980年 | 25篇 |
1979年 | 22篇 |
1978年 | 26篇 |
1977年 | 26篇 |
1976年 | 18篇 |
1975年 | 7篇 |
1973年 | 11篇 |
1972年 | 6篇 |
排序方式: 共有3308条查询结果,搜索用时 0 毫秒
141.
142.
Masuda Senichi Hosokawa Shunsuke Tachibana Naoji Ando Takashi Matsumoto Yoichi 《Industry Applications, IEEE Transactions on》1987,(1):120-126
The fundamental characteristics of the direct-coupled pulse energization in electrostatic precipitators (EP's) are investigated in a test rig comprised of a coal pulverizing facility, a furnace, a gas cooling system, and an EP. The EP consisted of a corona electrode with barbed wires and a collection electrode with 300-mm duct spacing. This simulates the type of EP normally used in a coal-fired power station. The pulse-energized collection field shows a very high collection performance of more than 99 percent collection efficiency and the performance enhancement compared to the conventional dc energization, causing very severe back corona, becomes as large as H = 2.50.H is the enhancement factor in terms of the Deutsch migration velocity in the case of the very high resistivity dust of rd = 2 x 1013 ?cm at the gas temperature of Tg = 150°C. Even at the lower level of the dust resistivity at Tg = 110°C, where no back corona occurs in the dc-energized collection field, the performance enhancement is as large as H = 1.21. The mechanism of such great performance enhancement is likely to be the result of the very uniform and very intense formation of corona plasmas on the wires as a result of the very fast rise in the pulse voltage applied and a special sawtooth waveform of the operating voltage between the corona and collection electrodes. 相似文献
143.
A. D. Arnold P. E. Castro T. K. Hatwar M. V. Hettel P. J. Kane J. E. Ludwicki M. E. Miller M. J. Murdoch J. P. Spindler S. A. Van Slyke K. Mameno R. Nishikawa T. Omura S. Matsumoto 《Journal of the Society for Information Display》2005,13(6):525-535
Abstract— A full‐color AMOLED display with an RGBW color filter pattern has been fabricated. Displays with this format require about one‐half the power of analogous RGB displays. RGBW and RGB 2.16‐in.‐diagonal displays with average power consumptions of 180 and 340 mW, respectively, were characterized for a set of standard digital still camera images at a luminance of 100 cd/m2. In both cases, a white‐emitting AMOLED was used as the light source, and standard LCD filters were used to provide the R, G, and B emission. The color gamuts of these displays were identical and the higher overall efficiency of the RGBW format results from two factors. First, a large fraction of a typical image is near neutral in color and can be reproduced using the white sub‐pixel. Second, the white sub‐pixel in an RGBW AMOLED display is highly efficient because of the absence of any color filter. The efficiency of these displays can be further enhanced by choosing a white emitter optimized to the target display white point (in this case D65). A two‐emission layer configuration based upon separate yellow and blue‐emitting regions is shown to be well suited for both the RGBW and RGB formats. 相似文献
144.
Katsuhiko Nakamura Author Vitae Masashi Matsumoto Author Vitae 《Pattern recognition》2005,38(9):1384-1392
This paper describes approaches for machine learning of context free grammars (CFGs) from positive and negative sample strings, which are implemented in Synapse system. The grammatical inference consists of a rule generation by “inductive CYK algorithm,” mechanisms for incremental learning, and search. Inductive CYK algorithm generates minimum production rules required for parsing positive samples, when the bottom-up parsing by CYK algorithm does not succeed. The incremental learning is used not only for synthesizing grammars by giving the system positive strings in the order of their length but also for learning grammars from other similar grammars. Synapse can synthesize fundamental ambiguous and unambiguous CFGs including nontrivial grammars such as the set of strings not of the form ww with w∈{a,b}+. 相似文献
145.
Hiroaki Matsumoto Sadao Watanabe Naoya Masahashi Shuji Hanada 《Metallurgical and Materials Transactions A》2006,37(11):3239-3249
The Young’s modulus of Ti-V and Ti-V-Sn alloys quenched from the β-phase region after solution treatment and cold rolling
was investigated in relation to alloy compositions, microstructures, and constituent phases. The composition dependence of
the Young’s modulus for quenched Ti-V binary alloys shows two minima of 69 GPa at Ti-10 mass pct V and 72 GPa at Ti-26 mass
pct V. Between the two compositions, athermalω or stress-induced ω is introduced in retainedβ phase and increases Young’s modulus. That is, a low Young’s modulus is attained unless alloys undergoω transformation. In Ti-5 and -8 mass pct V, which under goα′ (hcp) martensitic transformation on quenching, the Young’s modulus further decreases by cold rolling, which can be reasonably
explained by the formation ofα′ rolling texture. Comparing Young’s modulus in Ti-V binary alloy with that in Ti-Nb binary alloy, it is found that Young’s
modulus is remarkably increased by athermal- or stress inducedω phase, and it shows a minimum when both martensitic andω transformation are suppressed during quenching in metastableβ alloys. The Sn addition to Ti-V binary alloy retards or suppresses athermal and stress-inducedω transformation, thereby decreasing Young’s modulus. Young’s modulus exhibits minimum values of 51 GPa in quenched (Ti-12
pct V)-2 pct Sn and of 57 GPa in cold-rolled (Ti-12 pct V)-6 pct Sn. 相似文献
146.
Muramatsu D. Kondo M. Sasaki M. Tachibana S. Matsumoto T. 《Information Forensics and Security, IEEE Transactions on》2006,1(1):22-34
Authentication of handwritten signatures is becoming increasingly important. With a rapid increase in the number of people who access Tablet PCs and PDAs, online signature verification is one of the most promising techniques for signature verification. This paper proposes a new algorithm that performs a Monte Carlo based Bayesian scheme for online signature verification. The new algorithm consists of a learning phase and a testing phase. In the learning phase, semi-parametric models are trained using the Markov Chain Monte Carlo (MCMC) technique to draw posterior samples of the parameters involved. In the testing phase, these samples are used to evaluate the probability that a signature is genuine. The proposed algorithm achieved an EER of 1.2% against the MCYT signature corpus where random forgeries are used for learning and skilled forgeries are used for evaluation. An experimental result is also reported with skilled forgery data for learning. 相似文献
147.
High-accuracy measurement of 240-m distance in an optical tunnel by use of a compact femtosecond laser 总被引:1,自引:0,他引:1
A high-accuracy optical distance meter with a mode-locked femtosecond laser is proposed for distance measurements in a 310-m-long optical tunnel. We measured the phase shift of the optical beat component between longitudinal modes of a mode-locked laser. A high resolution of 50 mum at 240-m distance was obtained without cyclic error correction. The group refractive index of air is automatically extracted to an accuracy of 6 parts per million (ppm) by two-color measurement with the pulses of fundamental and second-harmonic wavelengths. Finally, an absolute mechanical distance of 240 m was obtained to within 8-ppm accuracy by use of a series of beat frequencies with the advantage of a wide range of intermode frequency, together with the results of the two-color measurement. 相似文献
148.
Matsumoto K. Takayanagi I. Nakamura T. Ohta R. 《Electron Devices, IEEE Transactions on》1991,38(5):989-998
The operational mechanism of the charge modulation device (CMD) as an image sensor is presented. A newly developed device simulator, the transistor analysis program for imagers calculating non-steady-state equations (TRINE) is used in this analysis. Comparison of the calculated results with measured data shows that the model predictions are consistent with measured electrical and optical characteristics within a range of 20%. The operational mechanism has been clarified, and the accuracy of the method proves that it is effective in quantitative device design. The discretization scheme of the cylindrical coordinate system used is also shown 相似文献
149.
A novel high-isolation structure for a polarisation-insensitive nonreciprocal device intended for optical circulator application is proposed. It consists of birefringent crystals and polarisation rotators. Experimental demonstration shows an isolation of over 42 dB and an insertion loss of under 1.5 dB.<> 相似文献
150.
H Shimizu Y Takizawa L Pulkkinen JJ Zone K Matsumoto T Saida J Uitto T Nishikawa 《Canadian Metallurgical Quarterly》1998,111(5):887-892
Most populations and some species of ticks of the genera Boophilus (5 spp.) and Rhipicephalus (ca. 75 spp.) cannot be distinguished phenotypically. Moreover, there is doubt about the validity of species in these genera. I studied the entire second internal transcribed spacer (ITS 2) rRNA of 16 populations of rhipicephaline ticks to address these problems: Boophilus microplus from Australia, Kenya, South Africa and Brazil (4 populations); Boophilus decoloratus from Kenya; Rhipicephalus appendiculatus from Kenya, Zimbabwe and Zambia (7 populations); Rhipicephalus zambesiensis from Zimbabwe (3 populations); and Rhipicephalus evertsi from Kenya. Each of the 16 populations had a unique ITS 2, but most of the nucleotide variation occurred among species and genera. ITS 2 rRNA can be used to distinguish the populations and species of Boophilus and Rhipicephalus studied here. Little support was found for the hypothesis that B. microplus from Australia and South Africa are different species. ITS 2 appears useful for phylogenetic inference in the Rhipicephalinae because in genetic distance, maximum likelihood, and maximum parsimony analyses, most branches leading to species had >95% bootstrap support. Rhipicephalus appendiculatus and R. zambeziensis are closely related, yet their ITS 2 sequences could be distinguished unambiguously. This lends weight to a previous proposal that Rhipicephcalus sanguineus and Rhipicephalus turanicus, and Rhipicephalus pumilio and Rhipicephalus camicasi, respectively, are conspecific, because each of these pairs of species had identical sequences for ca. 250 bp of ITS 2 rRNA. 相似文献