全文获取类型
收费全文 | 3589篇 |
免费 | 89篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 173篇 |
综合类 | 7篇 |
化学工业 | 930篇 |
金属工艺 | 139篇 |
机械仪表 | 79篇 |
建筑科学 | 62篇 |
能源动力 | 149篇 |
轻工业 | 313篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 362篇 |
一般工业技术 | 570篇 |
冶金工业 | 566篇 |
原子能技术 | 108篇 |
自动化技术 | 229篇 |
出版年
2023年 | 24篇 |
2022年 | 56篇 |
2021年 | 93篇 |
2020年 | 46篇 |
2019年 | 40篇 |
2018年 | 55篇 |
2017年 | 66篇 |
2016年 | 68篇 |
2015年 | 50篇 |
2014年 | 84篇 |
2013年 | 226篇 |
2012年 | 128篇 |
2011年 | 174篇 |
2010年 | 143篇 |
2009年 | 177篇 |
2008年 | 169篇 |
2007年 | 147篇 |
2006年 | 111篇 |
2005年 | 121篇 |
2004年 | 103篇 |
2003年 | 104篇 |
2002年 | 87篇 |
2001年 | 54篇 |
2000年 | 64篇 |
1999年 | 98篇 |
1998年 | 241篇 |
1997年 | 150篇 |
1996年 | 134篇 |
1995年 | 83篇 |
1994年 | 73篇 |
1993年 | 72篇 |
1992年 | 43篇 |
1991年 | 23篇 |
1990年 | 31篇 |
1989年 | 36篇 |
1988年 | 30篇 |
1987年 | 14篇 |
1986年 | 35篇 |
1985年 | 22篇 |
1984年 | 24篇 |
1983年 | 17篇 |
1982年 | 18篇 |
1981年 | 21篇 |
1980年 | 22篇 |
1979年 | 22篇 |
1978年 | 11篇 |
1977年 | 20篇 |
1976年 | 28篇 |
1973年 | 9篇 |
1972年 | 4篇 |
排序方式: 共有3690条查询结果,搜索用时 38 毫秒
61.
John Ogawa Bodand 《集成电路应用》2007,(1):34-39
随着器件尺寸的缩小。离子注入和退火等制程的可变性开始引起器件阈值电压的显著变化。对此。器件制造商有两个选择:要么围绕可变性来设计制程,要么改变制程设备。本文将探讨在65至32nm节点下DRAM与逻辑器件的各种可选择方案。 相似文献
62.
Tetsuya Iizuka Hideki Sezutsu Ken‐ichiro Tatematsu Isao Kobayashi Naoyuki Yonemura Keiro Uchino Kenichi Nakajima Katsura Kojima Chiyuki Takabayashi Hiroaki Machii Katsushige Yamada Hiroyuki Kurihara Tetsuo Asakura Yasumoto Nakazawa Atsushi Miyawaki Satoshi Karasawa Hatsumi Kobayashi Junji Yamaguchi Nobuo Kuwabara Takashi Nakamura Kei Yoshii Toshiki Tamura 《Advanced functional materials》2013,23(42):5232-5239
Silk is a protein fiber used to weave fabrics and as a biomaterial in medical applications. Recently, genetically modified silks have been produced from transgenic silkworms. In the present study, transgenic silkworms for the mass production of three colors of fluorescent silks, (green, red, and orange) are generated using a vector originating from the fibroin H chain gene and a classical breeding method. The suitability of the recombinant silks for making fabrics is investigated by harvesting large amounts of the cocoons, obtained from rearing over 20 thousand silkworms. The application of low temperature and a weakly alkaline solution for cooking and reeling enables the production of silk fiber without loss of color. The maximum strain tolerated and Young's modulus of the fluorescent silks are similar to those of ordinary silk, although the maximum stress value of the recombinant silk is slightly lower than that of the control. Fabrics with fluorescent color are demonstrated using the recombinant silk, with the color persisting for over two years. The results indicate that large amounts of genetically modified silk can be made by transgenic silkworms, and the silk is applicable as functional silk fiber for making fabrics and for use in medical applications. 相似文献
63.
T. Idehara I. Ogawa K. Kawahata H. Iguchi K. Matsuoka 《Journal of Infrared, Millimeter and Terahertz Waves》2004,25(11):1567-1579
Gyrotron FU II has been successfully applied as a submillimeter wave radiation source to plasma scattering measurements on the Compact Helical System (CHS) in National Institute for Fusion Science (NIFS) in Japan. The gyrotron operates in a long pulse mode (the pulse width is about 600 ms) at a frequency of about 350 GHz (the corresponding wavelength is 0.85 mm). The output power is about 110 W. The output power is transmitted along a circular waveguide system and converted to a Gaussian-like beam by a quasi-optical antenna. After that, the beam is directed onto the CHS plasma and the scattered signal is detected by a homodyne detection system. The frequency and the wave number of the scattered signal are analyzed. The results suggest that a broad band low frequency (several tens to several hundreds kHz) density fluctuation is excited in the CHS plasma only during neutral beam injection (NBI) or ion cyclotron resonance (ICR) heating. 相似文献
64.
S. Sabchevski T. Idehara I. Ogawa M. Glyavin S. Mitsudo K. Ohashi H. Kobayashi 《Journal of Infrared, Millimeter and Terahertz Waves》2000,21(8):1191-1209
Results from computer aided design of a novel electron gun generating axis-encircling beams are presented and discussed. Numerical experiments were performed by the new version of the software package GUN-MIG named GUN-MIG/CUSP. It is based on a self-consistent relativistic model and is developed as a problem oriented tool for analysis of electron-optical systems with magnetron injection guns (MIG) and electron guns with field reversal (cusp guns), forming axis-encircling beams. As a result of the simulations an electron-optical design of a novel electron gun with permanent magnet system was accomplished. The gun is expected to form high quality beams with small velocity spread and beam ripple. Parameters of the generated beams are appropriate for a prospective weakly relativistic high harmonic large orbit gyrotron (LOG). The development of such device is in progress now at the Research Center for Development of Far-Infrared Region (FIR Center) at Fukui University. 相似文献
65.
Ryosuke O. Suzuki Atsushi Nakagawa Hongtao Sui Takeyuki Fujisaka 《Journal of Electronic Materials》2013,42(7):1960-1965
A solar light concentrator composed of water and plastic transparent film has been designed. This flexible lens design can trace the solar movement through control of the tensile stress and amount of water, and concentrate the solar energy onto the thermoelectric (TE) module surface. An experimental water lens was constructed, and the concentrated intensity was monitored by a photodiode as a function of x–z position; For example, when 3.0 kg water was filled and tension of 69.0 N/m was applied to the transparent vinyl sheet, the concentration ratio was evaluated as the maximum of 28.0 at a depth of 657 mm from the water lens bottom surface. TE generation was tested to show the validity of the water lens. The surface condition of the receiver was found to be critical. 相似文献
66.
Michio Tajima Masatoshi Ikebe Yoshio Ohshita Atsushi Ogura 《Journal of Electronic Materials》2010,39(6):747-750
We investigated the effect of Fe contamination on the electronic properties of dislocation clusters in relation to oxygen
precipitation in multicrystalline silicon (mc-Si). Photoluminescence (PL) spectroscopy and mapping were performed at room
and liquid-He temperatures on mc-Si wafers before and after Fe contamination. PL spectra consisted of the band-edge emission,
the 0.78-eV emission associated with oxygen precipitates, and the dislocation-related D-lines. The Fe contamination increased
the electrically active dislocation clusters. Part of these clusters acted as preferential oxygen precipitation sites, and
their electronic properties were not further influenced by the Fe contamination. 相似文献
67.
Daisuke Kosemura Maki Hattori Tetsuya Yoshida Toshikazu Mizukoshi Atsushi Ogura 《Journal of Electronic Materials》2010,39(6):694-699
Defects and stress gradually accumulate throughout various Si large-scale integration fabrication processes. It is essential
to monitor defects and stress carefully to suppress their unintentional introduction. In this study, we measured the stress
and crystal quality in shallow trench isolation (STI) samples by ultraviolet (UV)-Raman spectroscopy with an extremely high-resolution
wavenumber to evaluate the effect of post-annealing on the recovery of Si crystals. The variations of crystal quality in 200-mm
wafers with STI structures gradually decreased after post-annealing for 4 h, 6 h, and 8 h; however, there was no substantial
difference in the values of full-width at half-maximum of the Raman spectra. Precise measurements of variations of stress
and crystal quality were successfully performed by UV-Raman spectroscopy with a high-resolution wavenumber, which enabled
us to evaluate the STI process accurately. 相似文献
68.
A new tomographic reconstruction method is proposed which permits the reconstruction of a region of interest within a slice from partially truncated scanning data. This method utilizes two types of source data, namely a series of truncated projections and the outline of the object's cross section. The principle of this algorithm is to estimate the outside area of truncation in one projection from the projection data of the other viewing angles and the outline data of the object. The above estimation is accomplished by following two repeated procedures: 1) the modification of the calculated projection data compared each time with the already measured projection data of the truncated area, and 2) the modification of the reconstructed image compared also each time with the shape of the object. Computer simulation shows the convergence of the results obtained by this algorithm thus verifying its validity, and a reconstructed image after iterative processes exhibits good quality. 相似文献
69.
Atsushi Hosoi Narumichi Sato Yasuyuki Kusumoto Keita Fujiwara Hiroyuki Kawada 《International Journal of Fatigue》2010,32(1):29-36
High-cycle fatigue features of over 108 cycles, particularly the initiation and propagation of edge delamination considering the effects of transverse cracks, were investigated using quasi-isotropic carbon-fiber-reinforced plastic (CFRP) laminates with a stacking sequence of [45/0/−45/90]s in this study. In the relationship between a transverse crack density and initiation and growth of edge delamination, it was found that fatigue damage growth behavior varied depending on applied stress. It was observed that edge delamination initiated and grew at parts where transverse cracks were dense at ordinary applied stress, whereas it was observed that edge delamination grew before or simultaneously with transverse crack propagation at a low applied stress and high-cycle loading. In addition, the critical transverse crack density where delamination begins growing was calculated to evaluate the interaction between transverse crack and edge delamination growth. 相似文献
70.
Maeda-Yamamoto M Saito T Nesumi A Tokuda Y Ema K Honma D Ogino A Monobe M Murakami A Murakami A Tachibana H 《Journal of the science of food and agriculture》2012,92(11):2379-2386
BACKGROUND: The purpose of this study was to evaluate the effects of leaf order or crop season on anthocyanins and other chemicals in the anthocyanin‐rich tea cultivar ‘Sunrouge’ (Camellia sinensis x C. taliensis) by using high‐performance liquid chromatography, and to study the effect of ‘Sunrouge’ extract on acetylcholinesterase (AChE) activity in human neuroblastoma SK‐N‐SH cells. RESULTS: The total anthocyanin content was higher in the third (3.09 mg g?1) than in the second (2.24 mg g?1) or first crop season (1.79 mg g?1). The amount of anthocyanins contained in the stem was high (1.61 mg g?1). In the third crop season, the concentrations of delphinidin‐3‐O‐β‐D ‐(6‐(E)‐p‐coumaroyl)galactopyranoside (DCGa), cyanidin‐3‐O‐β‐D ‐(6‐(E)‐p‐coumaroyl)galactopyranoside, delphinidin‐3‐O‐β‐D ‐galactopyranoside, delphinidin‐3‐O‐β‐D ‐(6‐O‐(Z)‐p‐coumaroyl)galactopyranoside, cyanidin‐3‐O‐β‐D ‐galactoside, and delphinidin‐3‐O‐β‐D ‐glucoside were 1.57 mg g?1, 0.52 mg g?1, 0.40 mg g?1, 0.22 mg g?1, 0.14 mg g?1, and 0.11 mg g?1, respectively. DCGa accounted for about 50% of the anthocyanins present. The suppressive effect of ‘Sunrouge’ water extract on AChE activity in human neuroblastoma SK‐N‐SH cells was the strongest among the three tea cultivars (‘Sunrouge’, ‘Yabukita’ and ‘Benifuuki’). CONCLUSION: These results suggested that ‘Sunrouge’ might protect humans from humans from AChE‐related diseases by suppressing AChE activity. To obtain sufficient amounts of anthocyanins, catechins and/or caffeine for a functional food material, ‘Sunrouge’ from the third crop season should be used. Copyright © 2012 Society of Chemical Industry 相似文献