全文获取类型
收费全文 | 636篇 |
免费 | 14篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 16篇 |
综合类 | 1篇 |
化学工业 | 101篇 |
金属工艺 | 9篇 |
机械仪表 | 16篇 |
建筑科学 | 9篇 |
能源动力 | 9篇 |
轻工业 | 26篇 |
水利工程 | 1篇 |
无线电 | 70篇 |
一般工业技术 | 104篇 |
冶金工业 | 216篇 |
原子能技术 | 21篇 |
自动化技术 | 53篇 |
出版年
2023年 | 9篇 |
2022年 | 10篇 |
2021年 | 14篇 |
2020年 | 5篇 |
2019年 | 7篇 |
2018年 | 12篇 |
2017年 | 7篇 |
2016年 | 10篇 |
2015年 | 6篇 |
2014年 | 5篇 |
2013年 | 21篇 |
2012年 | 24篇 |
2011年 | 30篇 |
2010年 | 16篇 |
2009年 | 28篇 |
2008年 | 25篇 |
2007年 | 14篇 |
2006年 | 20篇 |
2005年 | 15篇 |
2004年 | 13篇 |
2003年 | 11篇 |
2002年 | 9篇 |
2001年 | 15篇 |
2000年 | 6篇 |
1999年 | 22篇 |
1998年 | 70篇 |
1997年 | 60篇 |
1996年 | 26篇 |
1995年 | 19篇 |
1994年 | 16篇 |
1993年 | 20篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 7篇 |
1985年 | 13篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1976年 | 9篇 |
1975年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有652条查询结果,搜索用时 46 毫秒
31.
32.
33.
An optoelectronic self-oscillatory circuit with a constant time delay and its injection locking have been theoretically and experimentally described. The oscillation circuit incorporates a delayed feedback path by utilizing an optical fiber and is characterized by a differential-difference equation. The oscillation waveform and amplitude have been investigated by computing the equation. It is also shown that a stable frequency locking region exists and expands with an increase in the injection amplitude. By employing a carrier signal, two methods for optoelectronic oscillation, an AM and an FM type, are proposed and have been demonstrated to obtain more stable oscillation. 相似文献
34.
35.
36.
37.
We have developed a high-throughput deep-ultraviolet (DUV) Raman microspectrometer with excitation from a continuous wave (cw) laser operated at 244 nm that enables us to characterize thin surface layers of wide-gap semiconductors. This spectrometer system consists of a filter spectrometer for the rejection of stray light and a high-dispersion spectrograph combined with a liquid nitrogen cooled charge-coupled device (CCD) detector and extends the low-frequency limit of the observable spectral range down to 170 cm(-1). In the microscope we use a Cassegrain reflective objective for the collection of the scattered light and an off-axis mirror for introduction of the excitation laser light. DUV Raman spectroscopy has been applied for studying wide-gap semiconductors including SiC and AlGaN epitaxial films and shallow implanted layers of these materials. Raman spectra of various crystals have also been measured for examining the performance of this system. Resonance enhancement of Raman bands has been observed for several semiconductors, and the results are discussed. 相似文献
38.
39.
Masuda K Haramaki T Nakashima S Habert B Martinez I Kashiwabara S 《Applied spectroscopy》2003,57(3):274-281
The attenuated total reflectance infrared (ATR-IR) spectra of several aqueous solutions have been measured by using a newly developed heatable rod-type ATR cell. The OH stretching bands showed systematic change with increasing solute concentrations and these changes can be explained by four different OH components based on curve-fitting results. NaCl solutions show longer H-bond distance character, while carbonate solutions present shorter ones. The Na2CO3 1 M solution conserves this shorter H-bond nature up to 100 degrees C. On the other hand, the loose nature of NaCl solutions becomes less pronounced at higher temperatures because of the dissociation of pure water clusters. These in situ observations of water structures are generally in agreement with the expected nature of fluids within the earth. 相似文献
40.
Takeshi Ando Eiichi Ohki Yasutaka Nakashima Yutaka Akita Hiroshi Iijima Osamu Tanaka 《Advanced Robotics》2013,27(15):1727-1746
The article describes the development of a gait phase time-based split-belt treadmill measurement system. Conventional methods of measuring gait phase, such as the foot switch and force plate, require significant preparation and are costly. In this article, we propose a simple, cheap, and accurate gait phase measurement system that utilizes only the treadmill motor current value. Comparison of this algorithm with conventional methods reveals that the proposed algorithm is as accurate as the foot switch. Moreover, the proposed algorithm can estimate stance phase within a 0.2?s error of the measured value of the force plate in most cases (four out of five healthy subjects). This accuracy is higher than that of the foot switch which is widely used in the clinical field. 相似文献