全文获取类型
收费全文 | 1964篇 |
免费 | 64篇 |
国内免费 | 17篇 |
专业分类
化学 | 1439篇 |
晶体学 | 26篇 |
力学 | 23篇 |
数学 | 124篇 |
物理学 | 433篇 |
出版年
2023年 | 11篇 |
2022年 | 9篇 |
2021年 | 24篇 |
2020年 | 12篇 |
2019年 | 37篇 |
2018年 | 24篇 |
2017年 | 9篇 |
2016年 | 31篇 |
2015年 | 48篇 |
2014年 | 48篇 |
2013年 | 138篇 |
2012年 | 124篇 |
2011年 | 116篇 |
2010年 | 72篇 |
2009年 | 81篇 |
2008年 | 116篇 |
2007年 | 141篇 |
2006年 | 129篇 |
2005年 | 109篇 |
2004年 | 107篇 |
2003年 | 75篇 |
2002年 | 82篇 |
2001年 | 40篇 |
2000年 | 28篇 |
1999年 | 29篇 |
1998年 | 11篇 |
1997年 | 17篇 |
1996年 | 26篇 |
1995年 | 9篇 |
1994年 | 14篇 |
1993年 | 21篇 |
1992年 | 20篇 |
1991年 | 14篇 |
1990年 | 21篇 |
1989年 | 16篇 |
1988年 | 9篇 |
1987年 | 13篇 |
1986年 | 12篇 |
1985年 | 32篇 |
1984年 | 19篇 |
1983年 | 17篇 |
1982年 | 17篇 |
1981年 | 13篇 |
1980年 | 11篇 |
1979年 | 15篇 |
1978年 | 15篇 |
1977年 | 13篇 |
1976年 | 9篇 |
1975年 | 10篇 |
1973年 | 16篇 |
排序方式: 共有2045条查询结果,搜索用时 359 毫秒
1.
2.
A Necessary and Sufficient Condition for the Existence of a Heterochromatic Spanning Tree in a Graph
Kazuhiro Suzuki 《Graphs and Combinatorics》2006,22(2):261-269
We prove the following theorem. An edge-colored (not necessary to be proper) connected graph G of order n has a heterochromatic spanning tree if and only if for any r colors (1≤r≤n−2), the removal of all the edges colored with these r colors from G results in a graph having at most r+1 components, where a heterochromatic spanning tree is a spanning tree whose edges have distinct colors. 相似文献
3.
In this study, the nonlinear dynamic responses of a string are simulated using the Cellular Automata method based on the reflection rule. In the case of nonlinear systems, the velocity of wave propagation is not constant and depends on the amplitude. A new treatment of the dynamic time step is proposed for the Cellular Automata method considering the effect of the propagation velocity. As numerical examples, first, the dynamic responses of a string with linear characteristic are simulated using the Cellular Automata method. A typical resonance curve can be obtained. Second, the dynamic responses of a string with nonlinear characteristic are simulated using the proposed method. Some characteristic types of vibration can be obtained. It is concluded that the linear and nonlinear dynamic responses of a string may be obtained by simulation using the Cellular Automata method. 相似文献
4.
R. Bairava Ganesh Hitoshi Matsuo Takahiro Kawamura Yoshihiro Kangawa Koji Arafune Yoshio Ohshita Masafumi Yamaguchi Koichi Kakimoto 《Journal of Crystal Growth》2008,310(11):2697-2701
Multicrystalline silicon was grown by unidirectional solidification method using the accelerated crucible rotation technique. The application of the accelerated crucible rotation technique in unidirectional solidification method induced growth striations across the axial direction of the grown crystal. This striation pattern was observed from carbon concentration distribution, obtained by using Fourier transform infrared spectroscopy. The generated striation pattern was found to be weak and discontinuous. Some striations were absent, probably due to back melting, caused during each crucible rotation. From the growth striations and applied time period in crucible rotation, the growth rate was estimated by using Fourier transformation analysis. 相似文献
5.
6.
D. Kawamura A. Takita Y. Hayasaki N. Nishida 《Applied Physics A: Materials Science & Processing》2006,85(1):39-43
The morphology of a glass surface having a transparent coating processed with focused femtosecond laser pulses is investigated. The transparent coating is formed of poly-methyl methacrylate (PMMA). When the glass was coated with a PMMA film with a thickness of 2.8 μm, bumps were formed over a wide range of axial focus positions. The same laser pulse energy produced cavities when processing bare glass with no coating. The bumps were formed as a result of suppressing material emission from the glass surface by a shielding effect of plasma generated by ablation of the PMMA film and by physical blocking of the PMMA film. A thinner film with a thickness of 0.7 μm produced a reduced shielding effect, forming an exploded bump with a small pit at its center and debris around the periphery. PACS 44.10.+i; 61.80.Ba; 79.20.Ds 相似文献
7.
The self-restoration properties in VWP networks are investigated with optimization about spare wavelength by simulations. Rapid restoration can be achieved by selection of rerouting path with long delay and no delay-limitation for new routes. 相似文献
8.
Endoscopic Observation of Tissue by Narrowband Illumination 总被引:6,自引:0,他引:6
Kazuhiro Gono Kenji Yamazaki Nobuyuki Doguchi Tetsuo Nonami Takashi Obi Masahiro Yamaguchi Nagaaki Ohyama Hirohisa Machida Yasushi Sano Shigeaki Yoshida Yasuo Hamamoto Takao Endo 《Optical Review》2003,10(4):211-215
We propose a new illumination method for a medical endoscope: narrow band imaging (NBI), in which the spectral bandwidth of the filtered light is narrowed. To confirm how the spectral specifications of the filtered light influence a reproduced image, an experiment was conducted observing the endoscopic images of the back mucosa of a human tongue. In addition, the effect of NBI on endoscopic images was investigated through preliminary clinical tests in colonoscopy and upper gastrointestinal endoscopy. It has been shown that NBI can enhance the capillary pattern and the crypt pattern on the mucosa. These patterns are useful features for diagnosing an early cancer. 相似文献
9.