全文获取类型
收费全文 | 5977篇 |
免费 | 174篇 |
国内免费 | 17篇 |
专业分类
电工技术 | 377篇 |
综合类 | 19篇 |
化学工业 | 1386篇 |
金属工艺 | 193篇 |
机械仪表 | 184篇 |
建筑科学 | 127篇 |
能源动力 | 220篇 |
轻工业 | 541篇 |
水利工程 | 11篇 |
石油天然气 | 4篇 |
无线电 | 464篇 |
一般工业技术 | 1153篇 |
冶金工业 | 969篇 |
原子能技术 | 149篇 |
自动化技术 | 371篇 |
出版年
2023年 | 25篇 |
2022年 | 54篇 |
2021年 | 94篇 |
2020年 | 45篇 |
2019年 | 67篇 |
2018年 | 89篇 |
2017年 | 71篇 |
2016年 | 87篇 |
2015年 | 81篇 |
2014年 | 156篇 |
2013年 | 344篇 |
2012年 | 212篇 |
2011年 | 334篇 |
2010年 | 231篇 |
2009年 | 299篇 |
2008年 | 284篇 |
2007年 | 255篇 |
2006年 | 227篇 |
2005年 | 222篇 |
2004年 | 191篇 |
2003年 | 193篇 |
2002年 | 172篇 |
2001年 | 150篇 |
2000年 | 112篇 |
1999年 | 143篇 |
1998年 | 380篇 |
1997年 | 262篇 |
1996年 | 195篇 |
1995年 | 124篇 |
1994年 | 141篇 |
1993年 | 101篇 |
1992年 | 61篇 |
1991年 | 68篇 |
1990年 | 66篇 |
1989年 | 58篇 |
1988年 | 62篇 |
1987年 | 48篇 |
1986年 | 46篇 |
1985年 | 58篇 |
1984年 | 34篇 |
1983年 | 39篇 |
1982年 | 37篇 |
1981年 | 29篇 |
1980年 | 25篇 |
1979年 | 19篇 |
1978年 | 24篇 |
1977年 | 26篇 |
1976年 | 49篇 |
1975年 | 16篇 |
1974年 | 14篇 |
排序方式: 共有6168条查询结果,搜索用时 46 毫秒
1.
Tsuneaki Matsudaira Masashi Wada Naoki Kawashima Miyuki Takeuchi Daisaku Yokoe Takeharu Kato Masasuke Takata Satoshi Kitaoka 《Journal of the European Ceramic Society》2021,41(5):3150-3160
Mass transfer in polycrystalline Yb2SiO5 wafers with precise composition control was evaluated and analyzed by oxygen permeation experiments at high temperatures using an oxygen tracer. Oxygen permeation proceeded due to mutual grain boundary diffusion of oxide ions and Yb ions without synergistic effects such as acceleration or suppression. The oxygen shielding properties of Yb2SiO5 were compared with those of the other line compounds such as Yb2Si2O7 and Al2O3 based on the determined mass transfer parameters. It was found that the more preferentially an oxide ion diffuses in the grain boundary compared to the interior of the grain, the greater the effect of suppressing the movement of the oxide ion by applying an oxygen potential gradient becomes. 相似文献
2.
Shingo Urata Hiroyuki Hijiya Kazuhiko Niwano Jun Matsui 《Journal of the American Ceramic Society》2022,105(6):4200-4207
To theoretically explore amorphous materials with a sufficiently low dielectric loss, which are essential for next-generation communication devices, the applicability of a nonequilibrium molecular dynamics simulation employing an external alternating electric field was examined using alkaline silicate glass models. In this method, the dielectric loss is directly evaluated as the phase shift of the dipole moment from the applied electric field. This method enabled us to evaluate the dielectric loss in a wide frequency range from 1 GHz to 10 THz. It was observed that the dielectric loss reaches its maximum at a few THz. The simulation method was found to qualitatively reproduce the effects of alkaline content and alkaline type on the dielectric loss. Furthermore, it reasonably reproduced the effect of mixed alkalines on the dielectric loss, which was observed in our experiments on sodium and/or potassium silicate glasses. Alkaline mixing was thus found to reduce the dielectric loss. 相似文献
3.
H. Sakata A. Katagiri M. Yokoi T. Kato H. Morimoto 《Journal of Low Temperature Physics》2003,131(3-4):275-279
We have measured the tunneling spectra in Bi2Sr2CaCu2O8 with a scanning tunneling microscope(STM) at various tip-sample distances by changing the tunneling conductance in a controlled manner. When the tunneling conductance is increased from 1×10–9 to 1×10–5 S, the spectra do not show changes in particular. However, the gap value decreases steeply and the asymmetric back ground density of states turns inverted V-shaped one above 6×10–4 S. The changes in the tunneling spectra at the high tunneling conductances are explained by the enhancement of the local carrier density induced by the pressure that the STM tip applied to the sample. 相似文献
4.
5.
Ichiro Hirosawa Tetsuo Honma Kazuo Kato Naoto Kijima Yasuo Shimomura 《Journal of the Society for Information Display》2004,12(3):269-273
Abstract— We studied the influence of annealing in air on doped europium in BaMgAl10O17 by performing x‐ray absorption fine‐structure measurements. We determined the oxidation of doped divalent europium by annealing in air at over 500°C. The interatomic distance between the europium and the surrounding oxygen atoms was compressed by oxidation. It also appears that the oxidation process of europium is determined by the diffusion of oxygen into BaMgAl10O17. 相似文献
6.
7.
8.
Koji Yamada Kiyotaka Tomari Umaru Semo Ishiaku Hiroyuki Hamada 《Polymer Engineering and Science》2005,45(8):1059-1066
Fracture toughness of adjacent flow weld lines, defined as weld lines that occur when two flow fronts meet and continue to flow together in the same direction (meld line or hot weld line), was evaluated by the single‐edge notched‐bend (SENB) method using three differently‐shaped obstructive pins. Although the fracture toughness varied depending upon the shapes of the pin, the values could be standardized as the distance from the meeting point of the two flow fronts flowing around the pin. The fracture toughness decreased drastically from the meeting point along the weld line and then slightly increased. These characteristic features could be explained by flow‐induced molecular orientation at the weld line interface. The molecules around the meeting point that were initially oriented parallel to the weld line due to fountain flow were able to relax, and then entanglement across the weld line interface developed because the flow stopped in the middle of the filling process, resulting in high fracture toughness. In contrast, the material at the downstream side of the weld line continued flowing during the filling process, being stretched along the flow direction. So, the molecular orientation at this area could not relax. In addition, the V‐notch shape, i.e., the depth and length at the surface of the weld line, which also varied depending on the shape of the obstacles, was considered to be identical when the meeting point was allowed to be a datum point. Thus, the meeting point was found to be a significant factor when the properties of weld lines are investigated. POLYM. ENG. SCI., 45:1059–1066, 2005. © 2005 Society of Plastics Engineers 相似文献
9.
Yamaoka M. Shinozaki Y. Maeda N. Shimazaki Y. Kato K. Shimada S. Yanagisawa K. Osada K. 《Solid-State Circuits, IEEE Journal of》2005,40(1):186-194
An on-chip 1-Mb SRAM suitable for embedding in the application processor used in mobile cellular phones was developed. This SRAM supports three operating modes - high-speed active mode, low-leakage low-speed active mode, and standby mode - and uses a subdivisional power-line control (SPC) scheme. The combination of three operating modes and the SPC scheme realizes low-power operation under actual usage conditions. It operates at 300 MHz, with leakage of 25 /spl mu/A/Mb in standby mode, and 50 /spl mu/A/Mb at the low-leakage active mode. This SRAM also uses a self-bias write scheme that decreases of minimum operating voltage by about 100 mV. 相似文献
10.
Reduction of flash generated in a gas vent is of great concern for manufacturers of electronic parts. The present study proposes a theoretical model for flash generation through consideration of flow characteristics in a gas vent. The model predicts the factors controlling flash, i.e., material parameters such as zero‐shear viscosity, crystallization temperature, thermal conductivity, and heat capacity, and process parameters such as injection and mold wall temperatures, packing pressure, and the clearance of a gas vent. On the other hand, we measure the amount of flash generated in the molding of poly(phenylene sulfide) (PPS) composites containing glass fiber and spherical fillers (CaCO3 or Al2O3). Flash reduces with decreasing size of spherical fillers. These experimental data are successfully interpreted using the flash model. Polym. Eng. Sci., 45:198–206, 2005. © 2005 Society of Plastics Engineers 相似文献