全文获取类型
收费全文 | 1897篇 |
免费 | 43篇 |
国内免费 | 4篇 |
专业分类
化学 | 1315篇 |
晶体学 | 22篇 |
力学 | 22篇 |
数学 | 142篇 |
物理学 | 443篇 |
出版年
2021年 | 12篇 |
2020年 | 8篇 |
2019年 | 16篇 |
2018年 | 18篇 |
2017年 | 9篇 |
2016年 | 31篇 |
2015年 | 24篇 |
2014年 | 34篇 |
2013年 | 101篇 |
2012年 | 69篇 |
2011年 | 76篇 |
2010年 | 51篇 |
2009年 | 73篇 |
2008年 | 87篇 |
2007年 | 67篇 |
2006年 | 83篇 |
2005年 | 77篇 |
2004年 | 82篇 |
2003年 | 59篇 |
2002年 | 73篇 |
2001年 | 43篇 |
2000年 | 40篇 |
1999年 | 23篇 |
1998年 | 28篇 |
1997年 | 23篇 |
1996年 | 33篇 |
1995年 | 14篇 |
1994年 | 21篇 |
1993年 | 19篇 |
1992年 | 21篇 |
1991年 | 27篇 |
1990年 | 25篇 |
1989年 | 27篇 |
1988年 | 25篇 |
1987年 | 25篇 |
1986年 | 38篇 |
1985年 | 43篇 |
1984年 | 42篇 |
1983年 | 18篇 |
1982年 | 29篇 |
1981年 | 33篇 |
1980年 | 38篇 |
1979年 | 43篇 |
1978年 | 39篇 |
1977年 | 37篇 |
1976年 | 19篇 |
1975年 | 31篇 |
1974年 | 15篇 |
1973年 | 18篇 |
1972年 | 9篇 |
排序方式: 共有1944条查询结果,搜索用时 15 毫秒
1.
2.
3.
Noboru Nakatani 《Optical Review》2003,10(4):206-210
This paper describes a compulsorily phase locked differential interferometer using an orthogonally polarized light source of a modulated LD with high extinction ratio to reduce non-linearity of the interferometer caused by polarization cross-talk. The current modulated LD is used as a light source to make the interferometer compact and for the scanning phase of the interferometer. The interferometer is operated compulsorily at the maximum inclination point of the fringe intensity curve by fringe scanning and an electric system. A Wollaston prism of high extinction ratio (50 dB) is used to combine the polarizing beams and to make the polarization cross-talk very small. In one light source the polarized output beams are on the same propagation axis; in the other they have a small crossing angle (2.5 mrad ∼ 10 mrad) to completely exclude non-linearity of the interferometer causded by polarization cross-talk. Using jets of a gas mixture of nitrogen and ethylene, this interferometer was demonstrated to be useful in detecting the photothermal effect of a photothermal velocimeter under phase fluctuation in a turbulent flow. 相似文献
4.
5.
Hiroshi Maruyama Tadao Ishii Naruhiko Bamba Hironobu Maeda Akihisa Koizumi Yuzo Yoshikawa Hitoshi Yamazaki 《Physica C: Superconductivity and its Applications》1989,160(5-6):524-532
The temperature dependence of the extended X-ray absorption fine structure (EXAFS) is studied in the high Tc superconductors, YBa2Cu3O7−δ. The measurements were done at the Cu K-edge for samples of two orthorhombic phases (Tc≈90 K and ≈58 K, respectively) and a nonsuperconducting tetragonal phase. Interatomic distances and mean square relative displacements σ2 for Cu-O bonds are determined by the least squares refinement. The results indicate that values of σ2 increase near Tc for both the orthorhombic samples. It is concluded that this anomalous behavior related to Tc is caused by an anomalous vibration of oxygen atoms in the Ba-O layer. Changes in the Cu-O distances from 300 to 20 K are not found. 相似文献
6.
A. Noda S. Nakamura Y. Iwashita S. Sakabe M. Hashida T. Shirai S. Shimizu H. Tongu H. Ito H. Souda A. Yamazaki M. Tanabe H. Daido M. Mori M. Kado A. Sagisaka K. Ogura M. Nishiuchi S. Orimo Y. Hayashi A. Yogo S. Bulanov T. Esirkepov A. Nagashima T. Kimura T. Tajima T. Takeuchi K. Matsukado A. Fukumi Z. Li 《Laser Physics》2006,16(4):647-653
In order to widely spread out particle beams utilized in cancer therapy, laser-produced ions are developed as the injection beam for an ion synchrotron dedicated for cancer therapy. Such a laser ion source is expected to contribute largely to the realization of compactness of the size and low cost of the cancer therapy accelerator. The energy spectrum of the laser-produced ions, however, has no peak, but their intensities decrease exponentially according to the increase of the energy. For the purpose of modifying such a situation, we have proposed a scheme to rotate the beam in the longitudinal phase space with the use of the RF electric field, which is phase-adjusted with the pulse laser. We aim for a reduction of the energy spread of ± 5% selected by an energy analyzer and slits to ±1% by such phase rotation. For this purpose, a quarter wavelength resonator with two gaps with the same resonant frequency as the source laser has already been fabricated, together with its RF power source. The above phase rotation system and its recent experimental realization are presented. 相似文献
7.
Optical trapping forces of polystyrene microspheres are analyzed both theoretically and experimentally, and comparisons are
made between the two. Discrepancies are mainly caused by straight-ray approximation for axial trapping, and by trapping-position
vertical displacement due to gravity for transverse trapping. 相似文献
8.
Ryoko Chiba Ayako Ogasawara Teppei Kubo Hiroyuki Yamazaki Masuo Umino Yoichi Ishizuka 《Analytical sciences》2003,19(5):785-789
A column-switching high-performance liquid chromatographic method with fluorescence detection was developed for the simultaneous determination of four benzamide-type anti-psychotic drugs: sulpiride, tiapride, sultopride and metoclopramide in human serum. In this method, a TSKgel Super-ODS column was used as an analytical column, and a TSKgel G 2000SW was prepared as a pretreatment column. Under the optimized analytical conditions, four benzamide-type anti-psychotic drugs were eluted within 18 min. The detection limits (S/N = 3) for sulpiride, tiapride, sultopride and metoclopramide are 1 ng/ml, 4 ng/ml, 2 ng/ml and 0.5 ng/ml, respectively. Finally, the method was applied to the determination of sulpiride in human serum samples obtained after a single oral dose of sulpiride. 相似文献
9.
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
10.