全文获取类型
收费全文 | 143847篇 |
免费 | 19185篇 |
国内免费 | 12637篇 |
专业分类
化学 | 89277篇 |
晶体学 | 1738篇 |
力学 | 8768篇 |
综合类 | 772篇 |
数学 | 21929篇 |
物理学 | 53185篇 |
出版年
2024年 | 400篇 |
2023年 | 2280篇 |
2022年 | 3977篇 |
2021年 | 4346篇 |
2020年 | 4627篇 |
2019年 | 4534篇 |
2018年 | 5048篇 |
2017年 | 5049篇 |
2016年 | 6253篇 |
2015年 | 5997篇 |
2014年 | 7077篇 |
2013年 | 9212篇 |
2012年 | 13343篇 |
2011年 | 12918篇 |
2010年 | 9053篇 |
2009年 | 8417篇 |
2008年 | 7888篇 |
2007年 | 7335篇 |
2006年 | 6701篇 |
2005年 | 9417篇 |
2004年 | 7658篇 |
2003年 | 5283篇 |
2002年 | 3312篇 |
2001年 | 2658篇 |
2000年 | 2154篇 |
1999年 | 2433篇 |
1998年 | 2091篇 |
1997年 | 1871篇 |
1996年 | 2029篇 |
1995年 | 1611篇 |
1994年 | 1578篇 |
1993年 | 1232篇 |
1992年 | 1274篇 |
1991年 | 1176篇 |
1990年 | 951篇 |
1989年 | 690篇 |
1988年 | 576篇 |
1987年 | 457篇 |
1986年 | 427篇 |
1985年 | 370篇 |
1984年 | 277篇 |
1983年 | 190篇 |
1982年 | 169篇 |
1981年 | 127篇 |
1980年 | 91篇 |
1979年 | 80篇 |
1976年 | 120篇 |
1975年 | 73篇 |
1974年 | 87篇 |
1973年 | 81篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Milan Medved? 《Journal of Mathematical Analysis and Applications》2002,267(2):643-650
A criterion for the nonexplosion of solutions to semilinear evolution equations on Banach spaces is proved. The result is obtained by applying a modification of the Bihari type inequality to the case of a weakly singular nonlinear integral inequality. 相似文献
22.
Solitary waves and their bifurcations of KdV like equation with higher order nonlinearity 总被引:3,自引:1,他引:2
We investigate the KdV like equation with higher order nonlinearity ut + a(1 +bun)unux + uxxx = 0with n ≥ 1, a, b ∈ R and α≠ 0. The bifurcations and explicit expressions of solitary wave solutions for theequation are discussed by using the bifurcation method and qualitative theory of dynamical systems. Thebifurcation diagrams, existence and number of the solitary waves are given. 相似文献
23.
Guofen Yu Yuanci Gao Shenggang Liu Wenxiang Wang Jin Wu 《International Journal of Infrared and Millimeter Waves》2002,23(8):1261-1269
Analysis of the field distributions in a single biological cell under electromagnetic wave is given. With Debye approximation, the dielectric relaxation of each part of the cell, including the extracellular and cellular media, the cell membrane and the nuclear membrane, was taken into account. Making use of some typical parameters for a cell, the voltage across nuclear and cytoplasma membranes under electromagnetic waves are calculated up to millimeter wave frequency range. The calculated result indicates that it is unlikely to generate electroporation by present available millimeter wave sources. 相似文献
24.
Note on Bernstein polynomials and Kantorovich polynomials 总被引:2,自引:0,他引:2
Wang Xiaochun 《分析论及其应用》1991,7(2):99-105
We obtain two asymptotic representations of remainder of approximation of derivable functions by Bernstein polynomials and
Kantorovich polynomials separately. 相似文献
25.
Ronggang Wang 《Communications in Mathematical Physics》1991,137(3):587-597
A new type of vortices called Chern-Simons vortices is considered and the existence is established. 相似文献
26.
Wen Zhang Hui Huang Yu Ding Margherita Gavagnin Ernesto Mollo Guido Cimino Yue‐Wei Guo 《Helvetica chimica acta》2006,89(4):813-820
Three new polyoxygenated steroids, muricesteroid ( 1 ), and menellsteroids A ( 2 ) and B ( 3 ), were isolated from two species of the South China Sea gorgonian Muricella flexuosa and Menella verrucosa Brundin , respectively. The structures of these new compounds were elucidated on the basis of extensive spectroscopic analysis, chemical methods and comparison with known related compounds. 相似文献
27.
In the interaction of laser-plasma the system of Zakharov equation plays an important role.This system attracted many scientists' wide interest and attention.And the formation, evolution and interaction of the Langmuir solutions differ from solutions of the KDV equation. Here we consider the following generalized Zakharov system 相似文献
28.
ZHONG Hui WAN Mingxi JIANG Yifeng WANG Supin 《声学学报:英文版》2006,25(2):104-115
The present study was to investigate the differential imaging method for detecting HIFU (High Intensity Focused Ultrasound)-induced lesions and the estimation of variation of attenuation for lesion evaluation with log spectral difference algorithm. Experiment results of bovine muscle and liver in vitro were acquired. Several algorithms for lesion detection - Absolute Difference (AD), Sum Absolute Differences (SAD) and Sum Squared Differences (SSD) - were analyzed with several window sizes and threshold values. Then three attenuation parameters were compared to evaluate the degree of tissue damage. It was found that variation of the mean attenuation △α was an effective parameter to evaluate lesions. 相似文献
29.
The results of laser induced deposition of copper on polyimide substrate from copper electrolyte solution are reported. Unlike most work reported in the literatures where CW Ar+ lasers were used, a second harmonic (532 nm wavelength) Q-switch Nd:YAG laser was used for our experiments. The deposition process was conducted by laser-catalyzing of the polyimide surface and subsequent photothermal-accelerated reduction of copper-complex ions in an alkaline reducing environment. The characteristics of the deposited copper line were investigated in terms of laser beam scanning speed, and the number of scans. The surface morphology and chemical composition of the deposited copper were analyzed using field emission scanning electron microscope (FESEM) and energy dispersive spectrometer (EDX). The optimum processing conditions have been identified. The copper deposit was found to adhere well to the substrate. 相似文献
30.
王巨平 《中国科学A辑(英文版)》2002,45(7):827-835
This paper verifies the singularity conjecture for Jacobi forms with higher degree in some typical cases, and gives constructions
for the Jacobi cusp forms whose Fourier coefficients can be expressed by some kind of Rankin-typeL-series. 相似文献