全文获取类型
收费全文 | 787篇 |
免费 | 20篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 55篇 |
技术理论 | 1篇 |
综合类 | 10篇 |
化学工业 | 155篇 |
金属工艺 | 11篇 |
机械仪表 | 12篇 |
建筑科学 | 8篇 |
能源动力 | 5篇 |
轻工业 | 48篇 |
水利工程 | 3篇 |
石油天然气 | 8篇 |
武器工业 | 2篇 |
无线电 | 192篇 |
一般工业技术 | 100篇 |
冶金工业 | 157篇 |
原子能技术 | 18篇 |
自动化技术 | 34篇 |
出版年
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 16篇 |
2018年 | 8篇 |
2017年 | 9篇 |
2016年 | 9篇 |
2015年 | 6篇 |
2014年 | 13篇 |
2013年 | 22篇 |
2012年 | 17篇 |
2011年 | 31篇 |
2010年 | 19篇 |
2009年 | 20篇 |
2008年 | 21篇 |
2007年 | 33篇 |
2006年 | 30篇 |
2005年 | 18篇 |
2004年 | 28篇 |
2003年 | 24篇 |
2002年 | 27篇 |
2001年 | 20篇 |
2000年 | 20篇 |
1999年 | 28篇 |
1998年 | 65篇 |
1997年 | 57篇 |
1996年 | 35篇 |
1995年 | 27篇 |
1994年 | 26篇 |
1993年 | 30篇 |
1992年 | 9篇 |
1991年 | 8篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 13篇 |
1980年 | 7篇 |
1978年 | 7篇 |
1977年 | 11篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1972年 | 6篇 |
1971年 | 2篇 |
1970年 | 4篇 |
1969年 | 3篇 |
1968年 | 4篇 |
排序方式: 共有819条查询结果,搜索用时 15 毫秒
81.
Evaporation behavior of water/solvent blends was estimated using the universal functional activity coefficient, UNIFAC, method. The evaporation rate from a free surface of a waterborne coating, WBC, containing a co-solvent was experimentally determined. These results were used to estimate the evaporation rate from wet films of a WBC containing a variety of co-solvents with a range of initial thickness. Knowing the composition of the WBC during the drying process, the change in the viscosity and the surface tension was determined. The results strongly support the development of a surface tension gradient in the film. It is also suggested that a surface tension gradient would accelerate the leveling of the ribs if a proper co-solvent were employed. 相似文献
82.
LiuGuangyan HuangShunji 《电子科学学刊(英文版)》2003,20(5):337-343
Instantaneous Doppler frequency for squint SAR imaging has been found with Chirp Scaling Algorithm (CSA). Because the azimuth sample is not perpendicular to the range sample,the range signal must impact on the azimuth signal in the squint SAR data processing, and the different slant range targets have different Doppler frequencies. From the mathematical model of SAR echo signal, this paper carefully analyzes the instantaneous azimuth frequency, the instantaneous Doppler frequency component of the azimuth frequency and the impact of range chirp on azimuth frequency, which explains that Doppler frequency should be properly selected for correct SAR imaging in the squint SAR. The results of point target simulation experiments show that the way is reasonable for the squint SAR and can effectively complete range compression and azimuth focusing, and improve images‘ quality. 相似文献
83.
网格编码矢量量化在SAR原始数据压缩中的应用 总被引:1,自引:0,他引:1
本文提出了一种结合传统的块自适应量化与网格编码矢量量化对SAR原始数据进行压缩的方法。首先对SAR原始数据实施块自适应量化以减小数据的动态范围,然后对块自适应量化后的数据进行网格编码矢量量化。该方法在考虑了SAR原始数据特性的基础上较好地利用了矢量的空间相关性和信号的时间相关性,进一步提高了量化增益。仿真结果表明,该方法在SAR原始数据的压缩中取得了很好的效果。 相似文献
84.
85.
86.
87.
88.
A vacuolar type H(+)-ATPase inhibitor, concanamycin A (CMA), raised the pH and induced morphologic changes such as vacuolation in lytic granules in the CD8+ cytotoxic T lymphocyte clone OE4. Here we measured the pH in lytic granules present in OE4 by immunoelectron microscopic observation using (3-(2,4-dinitroanilino)-3'-amino-N-methyldipropylamine (DAMP) as a pH probe. In control OE4, only the peripheral region, but not cores, were heavily stained with DAMP. Exposure to 100 nM CMA for 60 min raised the pH in the lytic granules from 5.7 +/- 0.2 to 6.8 +/- 0.2. Furthermore, the number of lytic granules in OE4 was estimated under phase contrast microscopy after Wright staining. About 20 lytic granules in average were detected in control cells, while CMA induced vacuolation and decreased their number by 20 to 30%. 相似文献
89.
Takayuki Tomaru Shinji Miyoki Masatake Ohashi Kazuaki Kuroda Takashi Uchiyama Toshikazu Suzuki Akira Yamamoto Takakazu Shintomi Akitoshi Ueda Daisuke Tatsumi Shuichi Sato Koji Arai Masaki Ando Koji Watanabe Kenji Nakamura Masahiko Watanabe Kazuhiko Ito Izumi Kataoka Hiroaki Yamamoto Brett Bochner Yaron Hefetz 《Applied optics》2003,42(7):1306-1307
90.
In this paper, a new maximum likelihood (ML) classification algorithm is proposed to classify the multi-look polarimetric synthetic aperture radar (SAR) imagery. Experimental results with the NASA/JPL airborne L-band polarimetric SAR data demonstrate the effectiveness of the new algorithm. Furthermore, when using the algorithm in the classifications with subsets of the multi-look polarimetric SAR data, the polarization-channel optimization for the terrain type classification is implemented. 相似文献