全文获取类型
收费全文 | 122024篇 |
免费 | 11640篇 |
国内免费 | 6609篇 |
专业分类
电工技术 | 8736篇 |
技术理论 | 5篇 |
综合类 | 9782篇 |
化学工业 | 18779篇 |
金属工艺 | 7021篇 |
机械仪表 | 8136篇 |
建筑科学 | 9715篇 |
矿业工程 | 3872篇 |
能源动力 | 3292篇 |
轻工业 | 10352篇 |
水利工程 | 2737篇 |
石油天然气 | 6337篇 |
武器工业 | 1300篇 |
无线电 | 13365篇 |
一般工业技术 | 13191篇 |
冶金工业 | 5182篇 |
原子能技术 | 1528篇 |
自动化技术 | 16943篇 |
出版年
2024年 | 666篇 |
2023年 | 2234篇 |
2022年 | 4278篇 |
2021年 | 5636篇 |
2020年 | 4400篇 |
2019年 | 3390篇 |
2018年 | 3785篇 |
2017年 | 4281篇 |
2016年 | 3686篇 |
2015年 | 5252篇 |
2014年 | 6875篇 |
2013年 | 7798篇 |
2012年 | 8792篇 |
2011年 | 9355篇 |
2010年 | 8533篇 |
2009年 | 7867篇 |
2008年 | 7674篇 |
2007年 | 7298篇 |
2006年 | 6753篇 |
2005年 | 5525篇 |
2004年 | 3965篇 |
2003年 | 3127篇 |
2002年 | 3003篇 |
2001年 | 2499篇 |
2000年 | 2314篇 |
1999年 | 2281篇 |
1998年 | 1661篇 |
1997年 | 1468篇 |
1996年 | 1323篇 |
1995年 | 1078篇 |
1994年 | 850篇 |
1993年 | 621篇 |
1992年 | 524篇 |
1991年 | 347篇 |
1990年 | 263篇 |
1989年 | 227篇 |
1988年 | 167篇 |
1987年 | 100篇 |
1986年 | 86篇 |
1985年 | 50篇 |
1984年 | 52篇 |
1983年 | 37篇 |
1982年 | 36篇 |
1981年 | 31篇 |
1980年 | 36篇 |
1979年 | 14篇 |
1977年 | 2篇 |
1959年 | 9篇 |
1951年 | 10篇 |
1940年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
A photochromic nanocomposite based on Keggin structure phosphomolybdic acid (PMoA) well dispersed in polyethyleneglycol (PEG) was fabricated. TEM image showed that PMoA nanoparticles with narrow size distribution were finely dispersed in polymer matrix. FT-IR results showed that the Keggin geometry of polyoxometalates was still preserved inside the composites and strong coulombic interaction was built between PMoA and polymer matrix. Under UV irradiation, the film was reduced photochemically to yield a blue species, which was in accordance with a charge-transfer mechanism. 相似文献
32.
33.
BaMgAl10O17∶Eu2 (BAM) was prepared in the microemulsion system and its phase behavior was studied. There exists a small region in the reverse microemulsion system where the dispersed particles are of spherical form. In this way, BAM blue phosphor with good dispersion can be synthesized. The microemulsion phase diagrams of the pseudo-ternary system (Triton X-100/cosurfactant-oil-BAM brine) were first established intuitively by the dilution method. The microstructure of microemulsions was determined through eyeballing, conductance technique, and polar optical microscopy. Its phase behavior is affected by various factors, such as temperature (room temperature, 30, 40 ℃), oil, surfactants, and cosurfactants in microemulsions. According to the phase diagrams, the microemulsion system of Triton X-100/1-hexanol-hexane-BAM brine was chosen to prepare the precursor. The BAM phosphor can be obtained via sintering the precursor at a comparatively low temperature. The phosphors were characterized by XRD and vacuum ultraviolet (VUV) spectra. 相似文献
34.
35.
36.
目前的电路仿真软件通常是在电路中所有元件值都是给定的情况下得到一些数值结果,而非解析结果。该文利用Matlab的符号运算功能编程,通过节点列表法,实现了任意线性电路的自动解析求解,为电路分析提供了一个有效的辅助工具。 相似文献
37.
38.
39.
40.
Takeshi Shiofuku Norihiro Abe Yoshihiro Tabuchi Hirokazu Taki Shoujie He 《Artificial Life and Robotics》2008,13(1):290-293
This paper presents an approach of measuring in real-time the vector of finger that is pointing to an object. DSP is used
in the operation processing unit in order to do the real-time processing. The steps include the extraction of flesh-colored
regions from an image, the labeling of the flesh-colored regions, and the detection of two characteristic positions on the
finger so that the direction that the finger is pointing at will be calculated. The entire process takes about 29 msec, which
makes it possible to have the frame rate of 34 fps. With this frame rate, this measurement approach is considered real-time
and promising to be merged into other application systems.
This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January
31–February 2, 2008 相似文献