全文获取类型
收费全文 | 49634篇 |
免费 | 3389篇 |
国内免费 | 1031篇 |
专业分类
电工技术 | 1723篇 |
技术理论 | 4篇 |
综合类 | 1575篇 |
化学工业 | 9270篇 |
金属工艺 | 1975篇 |
机械仪表 | 2405篇 |
建筑科学 | 2022篇 |
矿业工程 | 764篇 |
能源动力 | 1769篇 |
轻工业 | 3476篇 |
水利工程 | 497篇 |
石油天然气 | 1020篇 |
武器工业 | 146篇 |
无线电 | 8059篇 |
一般工业技术 | 8101篇 |
冶金工业 | 3890篇 |
原子能技术 | 549篇 |
自动化技术 | 6809篇 |
出版年
2024年 | 123篇 |
2023年 | 606篇 |
2022年 | 1109篇 |
2021年 | 1584篇 |
2020年 | 1229篇 |
2019年 | 1166篇 |
2018年 | 1371篇 |
2017年 | 1351篇 |
2016年 | 1400篇 |
2015年 | 1525篇 |
2014年 | 2076篇 |
2013年 | 3128篇 |
2012年 | 2833篇 |
2011年 | 3379篇 |
2010年 | 2610篇 |
2009年 | 2712篇 |
2008年 | 2698篇 |
2007年 | 2366篇 |
2006年 | 2162篇 |
2005年 | 1748篇 |
2004年 | 1574篇 |
2003年 | 1604篇 |
2002年 | 1789篇 |
2001年 | 1515篇 |
2000年 | 1110篇 |
1999年 | 1011篇 |
1998年 | 1470篇 |
1997年 | 1048篇 |
1996年 | 821篇 |
1995年 | 675篇 |
1994年 | 562篇 |
1993年 | 466篇 |
1992年 | 346篇 |
1991年 | 316篇 |
1990年 | 312篇 |
1989年 | 272篇 |
1988年 | 214篇 |
1987年 | 214篇 |
1986年 | 188篇 |
1985年 | 168篇 |
1984年 | 146篇 |
1983年 | 109篇 |
1982年 | 80篇 |
1981年 | 81篇 |
1980年 | 105篇 |
1979年 | 65篇 |
1978年 | 74篇 |
1977年 | 79篇 |
1976年 | 109篇 |
1975年 | 56篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
181.
JaeHyunKim JounHoLee JiChulLim ChangHoonLee MooHyoungSong JuYeonYoon HeeDongChoi JeomJaeKim ChangHoOh SangDeogYeo 李路海 《现代显示》2004,31(5):31-33
薄膜晶体管液晶电视(TFT-LCD TV)因为具有薄、轻、紧凑和可随意放置的特点,已经占据了大部分电视机市场。除了这些物理特性以外,最重要的特性是已具有了良好像质的对比度。为了将对比度提高到1:600以上,对偏振片膜、背光源板、滤色片树脂、电极锥角和摩擦条件等都进行了研究。优化的背光板组合,光滑的电极锥角和摩擦方法的控制是提高对比度的主要控制因素。应用新开发的滤色片树脂,对获得高对比度最为有效。 相似文献
182.
Personality is an essential feature for creating socially interactive robots. Studies on this dimension will facilitate enhanced human–robot interaction (HRI). Using AIBO, a social robotic pet developed by Sony, we examined the issue of personality in HRI. In this gender-balanced 2 (AIBO personality: introvert vs. extrovert) by 2 (participant personality: introvert vs. extrovert) between-subject experiment (N = 48), we found that participants could accurately recognize a robot's personality based on its verbal and nonverbal behaviors. In addition, various complementarity attraction effects were found in HRI. Participants enjoyed interacting with a robot more when the robot's personality was complementary to their own personalities than when the robot's personality was similar to their own personalities. The same complementarity attraction effect was found in participants' evaluation of the robot's intelligence and social attraction. Participants' feelings of social presence during the interaction were a significant mediator for the complementarity attraction effects observed. Practical and theoretical implications of the current study for the design of social robots and the study of HRI were discussed. 相似文献
183.
Woo-Seog Song Seungbae Lee Dong-Shin Shin Yang Na 《Journal of Mechanical Science and Technology》2006,20(6):905-913
The instability curve of a Rijke tube system was obtained accurately by following different paths of heat power and flow-rate
for three regions and by defining its locus from the criterion based on the measured sound pressure levels. The unstable limits
in the region of flow-rate lower than that at the minimal power are compared with previous data. To observe the effect of
turbulence on the unstable limits, inflow turbulence was introduced by placing a bundle of circular cylinders upstream of
the heating part (50< Red< 700). The large-amplitude inflow fluctuation may delay the transition of the chamber acoustic mode to the unstable zone
even at a sufficient power. 相似文献
184.
185.
The stability of five major phenolics, namely (−)-epicatechin (EC), procyanidin B2 (PC-B2), chlorogenic acid (ChA), hyperoside (HP) and isoquercitrin (IQ), in hawthorn fruits and a canned hawthorn drink were evaluated during 6 months of storage in the dark at three different temperatures (4, 23 and 40 °C). HPLC with a diode-array detector was used to determine the contents of the individual compounds. The results showed that the studied phenolics in the hawthorn fruits and the drink were both stable at 4 °C and relatively unstable at 23 and 40 °C with varied extents of degradation. At room temperature (23 °C), marked degradations of EC and PC-B2 were observed in both the fruits and the drink with around 50% and 30% decrease after a 6-month storage, respectively. A more significant decrease of the phenolics was observed at 40 °C, especially for EC and PC-B2, which were almost completely degraded after a 6-month storage. HP, IQ and ChA were relatively stable at 23 °C, but unstable at 40 °C. Therefore, low-temperature storage is recommended for maintaining the quality and efficacy of hawthorn fruits and its preparations. 相似文献
186.
The relatively fast diffusion of Au atoms in eutectic PbSn matrix is considered one of the contributing factors to the Au
embrittlement problem. In this study, we further investigated the Au embrittlement problem in high-Sn solders. Experimentally,
Sn3.5Ag (wt.%) spheres with 500-μm diameter were soldered over the Au/Ni soldering pads. It was found that some of the AuSn4 needles that formed after reflow inside the solder migrated back to the solder/pad interface during thermal aging. However,
the migration kinetics in high-Sn solders was slower compared to that in eutectic PbSn. The difference in migration kinetics
of AuSn4 in eutectic PbSn and SnAg was ascribed to the difference in the magnitudes of the Au flux and the Ni flux. In eutectic PbSn,
the Au flux was much greater than that of the Ni flux, and the Au and Ni flux were in the same order of magnitude in eutectic
SnAg. The relative magnitude of the Au and Ni flux changed in eutectic PbSn and SnAg because the homologous temperatures of
PbSn and SnAg were different. 相似文献
187.
188.
189.
Shin S.-C. Ming-Da Tsai Ren-Chieh Liu Lin K.-Y. Huei Wang 《Microwave and Wireless Components Letters, IEEE》2005,15(7):448-450
A 24-GHz low-noise amplifier (LNA) was designed and fabricated in a standard 0.18-/spl mu/m CMOS technology. The LNA chip achieves a peak gain of 13.1 dB at 24 GHz and a minimum noise figure of 3.9 dB at 24.3 GHz. The supply voltage and supply current are 1 V and 14 mA, respectively. To the author's knowledge, this LNA demonstrates the lowest noise figure among the reported LNAs in standard CMOS processes above 20 GHz. 相似文献
190.