全文获取类型
收费全文 | 1210篇 |
免费 | 37篇 |
国内免费 | 8篇 |
专业分类
化学 | 670篇 |
晶体学 | 8篇 |
力学 | 70篇 |
数学 | 116篇 |
物理学 | 391篇 |
出版年
2023年 | 11篇 |
2022年 | 12篇 |
2021年 | 6篇 |
2019年 | 19篇 |
2018年 | 7篇 |
2017年 | 6篇 |
2016年 | 23篇 |
2015年 | 25篇 |
2014年 | 35篇 |
2013年 | 40篇 |
2012年 | 82篇 |
2011年 | 91篇 |
2010年 | 54篇 |
2009年 | 57篇 |
2008年 | 66篇 |
2007年 | 71篇 |
2006年 | 64篇 |
2005年 | 57篇 |
2004年 | 38篇 |
2003年 | 38篇 |
2002年 | 30篇 |
2001年 | 26篇 |
2000年 | 28篇 |
1999年 | 15篇 |
1998年 | 10篇 |
1997年 | 16篇 |
1996年 | 18篇 |
1995年 | 9篇 |
1994年 | 14篇 |
1993年 | 28篇 |
1992年 | 20篇 |
1991年 | 23篇 |
1990年 | 20篇 |
1989年 | 10篇 |
1988年 | 11篇 |
1987年 | 12篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1982年 | 13篇 |
1981年 | 11篇 |
1980年 | 12篇 |
1979年 | 15篇 |
1978年 | 11篇 |
1977年 | 9篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1972年 | 5篇 |
1970年 | 7篇 |
1969年 | 8篇 |
排序方式: 共有1255条查询结果,搜索用时 0 毫秒
101.
Cheng-Kang Chiang Mi-Chen Chiang Zong-Hong Lin Guo-Yu Lan Yang-Wei Lin Huan-Tsung Chang 《Journal of the American Society for Mass Spectrometry》2010,21(7):1204-1207
We have investigated six nanomaterials for their applicability as surfaces for the analyses of peptides and proteins using
surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). Gold nanoparticles (NPs) were useful nanomateriais
for small analytes (e.g., glutathione); Pt nanosponges and Fe3O4 NPs were efficient nanomaterials for proteins, with an upper detectable mass limit of ca. 25 kDa. Nanomateriais have several
advantages over organic matrices, including lower limits of detection for small analytes and lower batch-to-batch variations
(fewer problems associated with “sweet spois”), when used in laser desorption/ionization mass spectrometry. 相似文献
102.
We demonstrate that the simultaneous self-mode-locking of TEM0,0 and TEM1,0 modes can be achieved in a standard end-pumped Nd:YVO4 laser. With this simultaneous self-mode-locking, the transverse beat frequency can be accurately measured as a function of
the absorbed power. We employ the measured beat frequency and the cavity theory to precisely determine the effective focal
length of the thermal lens in the gain medium. 相似文献
103.
Chih-Wei Chiang Subrata Kumar Das Huang-Shih Liao 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(2):197-203
We report the first inter-comparison of vertical profiles of aerosols and clouds derived from space (CALIPSO) and ground based lidar over Chung-Li, Taiwan. Results show that inter-comparison is closer in case of aerosols than clouds. The strength/shortcoming of the comparison has been also discussed. An iterative calculation to retrieve extinction-to-backscatter ratio (lidar ratio) by using sun-photometer and CALIPSO data is also documented. By using the mentioned method, a mean lidar ratio of 23.5±8.2 sr was found. The derived lidar ratios are lower than former studies. The possible reasons for the difference have been discussed in this paper. The discussed methodology will be helpful to reduce the uncertainty of optical parameters derived from lidar data especially near the surface where the atmosphere is inhomogeneous. 相似文献
104.
Electronic chirality near the Dirac point is a key property of graphene systems, which is revealed by the spectral intensity patterns as measured by angle-resolved photoemission spectroscopy under various polarization conditions. Specifically, the strongly modulated circular patterns for monolayer (bilayer) graphene rotate by ±90° (±45°) in changing from linearly to circularly polarized light; these angles are directly related to the phases of the wave functions and thus visually confirm the Berry's phase of π (2π) around the Dirac point. The details are verified by calculations. 相似文献
105.
Y. F. Chen Y. J. Huang P. Y. Chiang Y. C. Lin H. C. Liang 《Applied physics. B, Lasers and optics》2011,103(4):841-846
A short-cavity Nd:YVO4 laser is employed to confirm that a spontaneous mode locking (SML) typically occurs without employing an extra nonlinearity.
We further experimentally demonstrate that reducing the number of longitudinal lasing modes can diminish the phase fluctuation
and effectively improve the SML pulse stability. Considering the spatial hole-burning (SHB) effect, an analytical expression
is derived to accurately estimate the number of longitudinal lasing modes for a practical design guideline. 相似文献
106.
A method, novel to our knowledge, for effective mirror image suppression in Fourier-domain optical coherence tomography based on a phase shift between neighboring A-mode scans is demonstrated. By realizing that the phase shifts of the real and mirror images are mutually reversed and assuming that the real image intensities of the two successive A-mode scans are the same, we can solve a set of two coupled equations to obtain the real image signals. The images based on the scanning of a high-resolution spectral-domain optical coherence tomography system are processed to show effective mirror image suppression results. Compared with a similar method of broad application, our approach has the advantages of shorter process time and higher flexibility in selecting the concerned image portions for processing. 相似文献
107.
Let An be the group of n×n even permutation matrices, and let Vn be the real linear space spanned by An. The purpose of this note is to characterize those linear operators φ on Vn satisfying φ(An)=An. This answers a question raised by C.K. Li, B.S. Tam, N.K. Tsing [Linear Algebra Appl., to appear]. 相似文献
108.
Kuei-Ming Chen Yen-Hsien Yeh Yin-Hao Wu Chen-Hao Chiang Din-Ru Yang Chu-Li Chao Tung-Wei Chi Yen-Hsang Fang Jenq-Dar Tsay Wei-I Lee 《Journal of Crystal Growth》2010,312(24):3574-3578
The bowing curvature of the free-standing GaN substrate significantly decreased almost linearly from 0.67 to 0.056 m−1 (i.e. the bowing radius increased from 1.5 to 17.8 m) with increase in inductively coupled plasma (ICP) etching time at the N-polar face, and eventually changed the bowing direction from convex to concave. Furthermore, the influences of the bowing curvature on the measured full width at half maximum (FWHM) of high-resolution X-ray diffraction (HRXRD) in (0 0 2) reflection were also deduced, which reduced from 176.8 to 88.8 arcsec with increase in ICP etching time. Decrease in the nonhomogeneous distribution of threading dislocations and point defects as well as VGa–ON complex defects on removing the GaN layer from N-polar face, which removed large amount of defects, was one of the reasons that improved the bowing of the free-standing GaN substrate. Another reason was the high aspect ratio of needle-like GaN that appeared at the N-polar face after ICP etching, which released the compressive strain of the free-standing GaN substrate. By doing so, crack-free and extremely flat free-standing GaN substrates with a bowing radius of 17.8 m could be obtained. 相似文献
109.
110.