全文获取类型
收费全文 | 10384篇 |
免费 | 2353篇 |
国内免费 | 621篇 |
专业分类
化学 | 1586篇 |
晶体学 | 47篇 |
力学 | 2565篇 |
综合类 | 125篇 |
数学 | 2329篇 |
物理学 | 6706篇 |
出版年
2024年 | 27篇 |
2023年 | 112篇 |
2022年 | 177篇 |
2021年 | 216篇 |
2020年 | 312篇 |
2019年 | 274篇 |
2018年 | 283篇 |
2017年 | 327篇 |
2016年 | 350篇 |
2015年 | 286篇 |
2014年 | 569篇 |
2013年 | 657篇 |
2012年 | 641篇 |
2011年 | 754篇 |
2010年 | 626篇 |
2009年 | 618篇 |
2008年 | 691篇 |
2007年 | 698篇 |
2006年 | 658篇 |
2005年 | 645篇 |
2004年 | 595篇 |
2003年 | 555篇 |
2002年 | 426篇 |
2001年 | 412篇 |
2000年 | 344篇 |
1999年 | 282篇 |
1998年 | 272篇 |
1997年 | 223篇 |
1996年 | 184篇 |
1995年 | 177篇 |
1994年 | 129篇 |
1993年 | 140篇 |
1992年 | 117篇 |
1991年 | 119篇 |
1990年 | 80篇 |
1989年 | 79篇 |
1988年 | 66篇 |
1987年 | 51篇 |
1986年 | 27篇 |
1985年 | 28篇 |
1984年 | 26篇 |
1983年 | 14篇 |
1982年 | 25篇 |
1981年 | 19篇 |
1980年 | 11篇 |
1979年 | 11篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1973年 | 6篇 |
1971年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Liangqi Gui Wei Guo ZuYin Zhang Shu Duan 《International Journal of Infrared and Millimeter Waves》2004,25(1):63-70
The image displaying methods used in a millimeter wave radiometric imaging system have great influence on its imaging quality. In order to obtain high quality millimeter wave radiometric images, intensive studies on the image displaying methods are needed. This paper describes the image displaying method of Ground-based 8mm Millimeter Wave Radiometric Imaging (GMWRI) system and compares two different image displaying methods. The experimental results prove the unequal size element arc displaying method fits GMWRI system better. 相似文献
62.
Miao Changxing 《数学学报(英文版)》1997,13(2):247-268
We consider the scattering problem for the Hartree equation with potential |x|−1 in a space of dimensionn≥2. We prove the existence ofH
m
-modified wave operator for Hartree equation on a dense set of a neighborhood of zero inH
m
(ℝ
n
), meanwhile, we obtain also the global existence for the Cauchy problem of Hartree equation in a space of dimensionn≥2.
This project is supported by the National Natural Science Foundation of China, 19601005 相似文献
63.
Field equations of the S2 sigma model (“the A3 model”) with spontaneously broken Z(2) symmetry are presented for (D+1)-dimensional space–time. The A3 model is an extension of the sine-Gordon equation (SGE) and supports kink-like U(1) charged solitons which are a generalization of neutral solitons of the SGE. The natural question arises — is the A3 model completely integrable in (1+1)-dimensional space–time? The Lorentz-invariant scalar A3 field can be viewed as a promising alternative to the Higgs field. 相似文献
64.
Vlase T. Vlase G. Chiriac A. Doca N. 《Journal of Thermal Analysis and Calorimetry》2003,72(3):839-845
The thermal decomposition in non-isothermal conditions of formates, acetates, propionates and butyrates of Mn, Co, Zn, Cd,
Eu, Sm and Ni was studied. The observed compensation effect allows us to calculate the isokinetic temperature. A selective
activation mechanism was suggested. This leads to a good agreement between kinetic and spectroscopic data.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
65.
Uwe Bandelow Mindaugas Radziunas Andrei Vladimirov Bernd Hüttl Ronald Kaiser 《Optical and Quantum Electronics》2006,38(4-6):495-512
We study both theoretically and experimentally typical operation regimes of 40 GHz monolithic mode-locked lasers. The underlying
Traveling Wave Equation model reveals quantitative agreement for characteristics of the fundamental mode-locking as pulse
width and repetition frequency tuning, as well as qualitative agreement with the experiments for other dynamic regimes. Especially
the appearance of stable harmonic mode-locking at 80 GHz has been predicted theoretically and confirmed by measurements. Furthermore,
we derive and apply a simplified Delay-Differential-Equation model which guides us to a qualitative analysis of bifurcations
responsible for the appearance and the breakup of different mode-locking regimes. Higher harmonics of mode-locking are predicted
by this model as well. 相似文献
66.
Juray De Wilde Denis Constales Geraldine J. Heynderickx Guy B. Marin 《International Journal of Multiphase Flow》2007
The propagation speeds of linear waves in gas–solid suspensions depend strongly on the solids volume fraction and the wave frequency. The latter is due to gas–solid momentum transfer and allows a simple test on filtered gas–solid momentum transfer models. Such models may predict linear wave propagation speeds different from those obtained with the non-filtered model at wave frequencies higher than the filter frequency, but not at wave frequencies lower than the filter frequency. 相似文献
67.
Frank Natterer Olga Klyubina 《计算数学(英文版)》2007,25(3):368-373
We study the initial value problem of the Helmholtz equation with spatially variable wave number. We show that it can be stabilized by suppressing the evanescent waves. The stabilized Helmholtz equation can be solved numerically by a marching scheme combined with FFT. The resulting algorithm has complexity n^2 log n on a n x n grid. We demonstrate the efficacy of the method by numerical examples with caustics. For the Maxwell equation the same treatment is possible after reducing it to a second order system. We show how the method can be used for inverse problems arising in acoustic tomography and microwave imaging. 相似文献
68.
69.
70.