全文获取类型
收费全文 | 1378篇 |
免费 | 36篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 53篇 |
化学工业 | 236篇 |
金属工艺 | 48篇 |
机械仪表 | 23篇 |
建筑科学 | 22篇 |
能源动力 | 29篇 |
轻工业 | 62篇 |
水利工程 | 2篇 |
无线电 | 248篇 |
一般工业技术 | 183篇 |
冶金工业 | 389篇 |
原子能技术 | 53篇 |
自动化技术 | 68篇 |
出版年
2023年 | 5篇 |
2022年 | 9篇 |
2021年 | 12篇 |
2020年 | 15篇 |
2019年 | 16篇 |
2018年 | 13篇 |
2017年 | 21篇 |
2016年 | 31篇 |
2015年 | 15篇 |
2014年 | 30篇 |
2013年 | 55篇 |
2012年 | 26篇 |
2011年 | 43篇 |
2010年 | 45篇 |
2009年 | 43篇 |
2008年 | 45篇 |
2007年 | 32篇 |
2006年 | 45篇 |
2005年 | 33篇 |
2004年 | 35篇 |
2003年 | 47篇 |
2002年 | 48篇 |
2001年 | 39篇 |
2000年 | 23篇 |
1999年 | 42篇 |
1998年 | 145篇 |
1997年 | 73篇 |
1996年 | 71篇 |
1995年 | 39篇 |
1994年 | 38篇 |
1993年 | 35篇 |
1992年 | 25篇 |
1991年 | 18篇 |
1990年 | 18篇 |
1989年 | 21篇 |
1988年 | 12篇 |
1987年 | 10篇 |
1986年 | 19篇 |
1985年 | 16篇 |
1984年 | 16篇 |
1983年 | 11篇 |
1982年 | 12篇 |
1981年 | 15篇 |
1980年 | 10篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1972年 | 3篇 |
排序方式: 共有1416条查询结果,搜索用时 15 毫秒
1.
H. Yamamoto N. Heyamoto T. Matsui N. Murayama J. Shibata 《International Journal of Thermophysics》2003,24(5):1385-1394
Polyvinylalcohol (PVA) polymer gel is a temperature sensitive polymeric gel, with a critical transition temperature (with H2O) of 310 K. At higher than 310 K, this temperature sensitive polymer gel shrinks because of discharging water, whereas at lower temperatures, the gel swelled because of absorbing water. The reversibility of the gel's volume change was confirmed by temperature swing. The adsorption behavior of an organic compound onto the PVA polymer gel in water was tested at various temperatures. The amount of adsorbed organic compound increased remarkably at temperatures higher than about 310 K. Then, it was confirmed that the organic compound in PVA polymer gel could be reversibly adsorbed and desorbed by a temperature change between 293 and 323 K. The mechanism of adsorption of the organic compound onto the PVA polymer gel could be explained by hydration and dehydration of polymer gel. 相似文献
2.
We derive a linear correspondence between the variables of an encoder and those of a corresponding syndrome former. Using the derived correspondence, we show that the log-likelihood ratio of an information bit conditioned on a received sequence can be equally calculated using the syndrome trellis. It is shown that the proposed method also applies to recursive systematic convolutional codes which are typical constituent codes for turbo codes. Moreover, we show that soft-in syndrome decoding considering a priori probabilities of information bits is possible in the same way as for Viterbi decoding based on the code trellis. Hence, the proposed method can be applied to iterative decoding such as turbo decoding. We also show that the proposed method is effective for high-rate codes by making use of trellis modification. 相似文献
3.
D Averill D Blockus B Brabson J Brom C Jung H Ogren DR Rust M Derrick P Kooijman JS Loos B Musgrave LE Price J Repond K Sugano B Cork C Akerlof J Chapman D Errede MT Ken DI Meyer H Neal D Nitz R Thun R Tschirhart S Abachi P Baringer BG Bylsma R DeBonte D Koltick EH Low RL McIlwain DH Miller CR Ng EI Shibata 《Canadian Metallurgical Quarterly》1989,39(1):123-137
4.
1-GHz-spaced 16-channel arrayed-waveguide grating for a wavelength reference standard in DWDM network systems 总被引:3,自引:0,他引:3
We fabricated a 1-GHz-spaced 16-channel arrayed-waveguide grating (AWG) by using a new AWG configuration where the path of each arrayed waveguide winds backward and forward across a 4-in diameter wafer without crossing any other waveguides. The ultra-narrow (< 1 GHz) and stable transmission bands of this AWG can be used to construct a wavelength reference standard covering the S, C, and L bands in the dense wavelength-division-multiplexing network systems whose frequency deviation is /spl plusmn/160 MHz. 相似文献
5.
S. Kamei M. Oguma M. Kohtoku T. Shibata Y. Inoue 《Photonics Technology Letters, IEEE》2005,17(4):798-800
We describe a low-loss athermal silica-based interleave filter with a lattice-form structure. We athermalize the filter by using a silicone-filled groove formed in each delay line and we employ a low-loss design to reduce the accumulated groove excess loss in the multiple delay lines. By using these designs, we obtained a very low groove excess loss of 0.4 dB and achieved satisfactory temperature insensitivity and optical characteristics with this filter. 相似文献
6.
Kamei S. Inoue Y. Mizuno T. Shibata T. Kaneko A. Takahashi H. Iemura K. 《Electronics letters》2005,41(9):544-546
A silica-based 1.5%-/spl Delta/ 100 GHz-spacing 32-channel athermal arrayed-waveguide grating (AWG) with compact size and extremely low insertion loss is described. By reducing the fibre coupling loss and the excess loss in a silicone-filled groove, an insertion loss of 1.3 dB was achieved with this athermal AWG. 相似文献
7.
Living organisms including humans drive circadian rhythm, and this rhythm influences the social structure and daily life of human beings. The suprachiasmatic nucleus (SCN) has been established as a pacemaker for mammalian circadian rhythm. There are many kinds of neurotransmitters and neuromodulators in this nucleus. The circadian systems are involved in oscillation, input (entrainment) and output (overt rhythm). Therefore in this review, pharmacological characteristics of circadian systems in relation to the SCN are discussed by focussing especially upon the roles of various neurotransmitters and modulators. 相似文献
8.
In this paper, we study the existence of cycles of all lengths in the recursive circulant graphs, and we show a necessary and sufficient condition for the graph being pancyclic and bipancyclic. 相似文献
9.
To deal with circulated bills in various conditions regarding size, shape, and rigidity, we have developed a new bill-stacking
cassette that can accept and re-dispense various-sized bills. This cassette stacks the bills upright by using deforming guides
and sheet rollers under our newly developed “phase control”. It was experimentally verified by stacking tests that the cassette
can handle bills in various conditions; thus, we conclude that the new cassette is practical for stacking circulated bills
and re-dispensing them securely.
Received: 14 August 2001/Accepted: 11 December 2001 相似文献
10.
Martin E. Valdez H. Shibata Alan W. Cramb 《Metallurgical and Materials Transactions B》2006,37(6):959-965
The objective of this study is to determine the conditions under which the inclusions present in liquid steel can act as heterogeneous
nucleants for solidification. In order to study the factors that define the undercooling of a given metal/oxide couple, the
undercooling of a pure iron sessile droplet in contact with Al2O3, ZrO2, and MgO substrates was measured under controlled oxygen partial pressures by observing droplet recalescence. The results
showed that the undercooling of iron, in contact with a particular substrate, did not have a unique value, but was significantly
affected by the oxygen content on the gas phase. For oxygen partial pressures between 10−21 and 10−19, the undercooling of iron on ZrO2 substrates was stable and around 290 °C. In the same range of oxygen partial pressure, the undercooling of iron on MgO substrates
remained below 100 °C due to the low stability of this oxide. At lower oxygen contents, substrate decomposition might be the
cause for the observed drop in the undercooling of iron on ZrO2 substrates to below 100 °C. The undercooling also decreased for increasing oxygen content as verified when the gas was changed
from gettered Ar/Ar-H2 to CO/CO2 mixtures. The variation in undercooling was related to the wetting of the substrate by the liquid metal, where the deep undercooling
observed in the ZrO2 experiments occurred when the highest contact angle between the liquid metal and the substrate was achieved. 相似文献