全文获取类型
收费全文 | 5442篇 |
免费 | 142篇 |
国内免费 | 28篇 |
专业分类
化学 | 3796篇 |
晶体学 | 79篇 |
力学 | 85篇 |
数学 | 410篇 |
物理学 | 1242篇 |
出版年
2022年 | 37篇 |
2021年 | 37篇 |
2020年 | 64篇 |
2019年 | 77篇 |
2018年 | 49篇 |
2017年 | 51篇 |
2016年 | 90篇 |
2015年 | 102篇 |
2014年 | 102篇 |
2013年 | 304篇 |
2012年 | 275篇 |
2011年 | 306篇 |
2010年 | 168篇 |
2009年 | 199篇 |
2008年 | 314篇 |
2007年 | 325篇 |
2006年 | 312篇 |
2005年 | 269篇 |
2004年 | 219篇 |
2003年 | 212篇 |
2002年 | 213篇 |
2001年 | 110篇 |
2000年 | 138篇 |
1999年 | 82篇 |
1998年 | 64篇 |
1997年 | 65篇 |
1996年 | 84篇 |
1995年 | 60篇 |
1994年 | 41篇 |
1993年 | 55篇 |
1992年 | 84篇 |
1991年 | 55篇 |
1990年 | 55篇 |
1989年 | 52篇 |
1988年 | 67篇 |
1987年 | 61篇 |
1986年 | 57篇 |
1985年 | 76篇 |
1984年 | 75篇 |
1983年 | 43篇 |
1982年 | 62篇 |
1981年 | 48篇 |
1980年 | 61篇 |
1979年 | 56篇 |
1978年 | 50篇 |
1977年 | 47篇 |
1976年 | 33篇 |
1975年 | 39篇 |
1974年 | 35篇 |
1973年 | 31篇 |
排序方式: 共有5612条查询结果,搜索用时 15 毫秒
1.
J. Kobayashi Y. Izumi M. Kumakura Y. Takahashi 《Applied physics. B, Lasers and optics》2006,83(1):21-25
By stabilizing the beam pointing of optical trapping beams, we have succeeded in stable formation of Bose–Einstein condensate
(BEC) of 87Rb with all-optical method. The thermal effect of acousto-optic modulator (AOM) is usually one of the most serious problems
to induce beam-pointing instability, especially for high power CO2 laser. By passing the beam through AOM twice, we have improved the beam pointing from about 4.8 mrad to less than 0.4 mrad,
which has been experimentally confirmed to be small enough to stably form BEC at the crossed region of CO2 lasers as well as to perform experiments using an optical lattice which might have been affected by beam-pointing instability.
PACS 32.80.Pj; 42.79.Jq; 03.75.Mn 相似文献
2.
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
3.
The first aim in the present paper is to give an integral representation for Beppo Levi functions on R
n. Our integral representation is an extension of Sobolev's integral representation given for infinitely differentiable functions with compact support. As applications, continuity and differentiability properties of Beppo Levi functions are studied.Our second aim in this paper is to study the existence of limits at infinity for Beppo Levi functions. We also consider the existence of fine-type limits at infinity with respect to Bessel capacities, which yields the radial limit result at infinity. 相似文献
4.
5.
6.
7.
Hiroshi Yamauchi Keiko Takahashi Mari Mashiko Juichiro Saitoh Yukio Yamamura 《应用有机金属化学》1992,6(4):383-388
We calculated the intake of each chemical species of dietary arsenic by typical Japanese, and determined urinary and blood levels of each chemical species of arsenic. The mean total arsenic intake by 35 volunteers was 195±235 (15.8-1039) μg As day?1, composed of 76% trimethylated arsenic (TMA), 17.3% inorganic arsenic (Asi), 5.8% dimethylated arsenic (DMA), and 0.8% monomethylated arsenic (MA): the intake of TMA was the largest of all the measured species. Intake of Asi characteristically and invariably occurred in each meal. Of the intake of Asi, 45-75% was methylated in vivo to form MA and DMA, and excreted in these forms into urine. The mean measured urinary total arsenic level in 56 healthy volunteers was 129±92.0 μg As dm?3, composed of 64.6% TMA, 26.7% DMA, 6.7% Asi and 2.2% MA. The mean blood total arsenic level in the 56 volunteers was 0.73±0.57 μg dl?1, composed of 73% TMA, 14% DMA and 9.6% Asi. The urinary TMA levels proved to be significantly correlated with the whole-blood TMA levels (r = 0.376; P<0.01). 相似文献
8.
The present paper gives a more complete treatment of the scattering from a two-dimensional random surface than previous works. Reciprocal theorems for the stochastic wave field and the incoherent scattering distribution (bistatic cross section) are derived and the presence of backscattering enhancement in the case of a slightly random Neumann surface is demonstrated. A physical interpretation of the backscattering enhancement associated with the presence of anomalous scattering on a slightly random Neumann surface is given. Some numerical calculations are performed to show the incoherent scattering distribution and the backscattering enhancement. 相似文献
9.
10.