全文获取类型
收费全文 | 9963篇 |
免费 | 1837篇 |
国内免费 | 1216篇 |
学科分类
数理化 | 13016篇 |
出版年
2024年 | 26篇 |
2023年 | 216篇 |
2022年 | 277篇 |
2021年 | 403篇 |
2020年 | 479篇 |
2019年 | 528篇 |
2018年 | 415篇 |
2017年 | 375篇 |
2016年 | 550篇 |
2015年 | 532篇 |
2014年 | 639篇 |
2013年 | 767篇 |
2012年 | 971篇 |
2011年 | 953篇 |
2010年 | 682篇 |
2009年 | 585篇 |
2008年 | 661篇 |
2007年 | 628篇 |
2006年 | 537篇 |
2005年 | 429篇 |
2004年 | 294篇 |
2003年 | 261篇 |
2002年 | 297篇 |
2001年 | 273篇 |
2000年 | 166篇 |
1999年 | 207篇 |
1998年 | 148篇 |
1997年 | 105篇 |
1996年 | 113篇 |
1995年 | 76篇 |
1994年 | 74篇 |
1993年 | 70篇 |
1992年 | 52篇 |
1991年 | 53篇 |
1990年 | 46篇 |
1989年 | 37篇 |
1988年 | 22篇 |
1987年 | 19篇 |
1986年 | 13篇 |
1985年 | 9篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1971年 | 1篇 |
1959年 | 2篇 |
1936年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Raman spectra of ceramic Sr2Bi4Ti5O18 (SBTi5) are reported to consist of four different Raman bands. Temperature-dependent spectra reveal the relationship between the lattice vibration and the material's structure. There appears a relatively large change in structure of the material at about 273K, The anharmonic potential of the material has a great influence on its phonon mode full width at half maximum (FWHM), which can be expressed by a function of temperature. Theoretical fittings of the FWHMs for the two modes at around 312 cm^-1 and 464cm^-1 indicate that the latter phonon mode is more anharmonic than the former one. 相似文献
42.
0 Introduction
In this paper, we give another proof of the scattering result of the following Cauchy problem in the energy space 相似文献
43.
Guangyan Jia 《Comptes Rendus Mathematique》2006,342(9):685-688
In this Note, we deal with one-dimensional backward stochastic differential equations (BSDEs) where the coefficient is left-Lipschitz in y (may be discontinuous) and Lipschitz in z, but without explicit growth constraint. We prove, in this setting, an existence theorem for backward stochastic differential equations. To cite this article: G. Jia, C. R. Acad. Sci. Paris, Ser. I 342 (2006). 相似文献
44.
Hongwei Yu 《General Relativity and Gravitation》1991,23(3):297-304
By solving the coupled SU(5) Einstein-Yang-Mills-Higgs equations, we obtain the exact Reissner-Nordstrom type gravitational field of a family of spherically symmetric SU(5) dyons with magnetic charge 1/2e. 相似文献
45.
Wang Yongqian Liao Xianbo Diao Hongwei Cheng Wenchao Li Guohua Chen Changyong Zhang Shibin Xu Yanyue Chen Weide Kong Guanglin 《中国科学A辑(英文版)》2002,45(10):1320-1328
A set of a-SiOx:H (0.52 <x< 1.58) films are fabricated by plasma-enhanced-chemical-vapor-deposition (PECVD) method at the substrate temperature
of 250°C. The microstructure and local bonding configurations of the films are investigated in detail using micro-Raman scattering,
X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). It is found that the films are
structural inhomogeneous, with five phases of Si, Si2O:H, SiO:H, Si2O3:H and SiO2 that coexist. The phase of Si is composed of nonhydrogenated amorphous silicon (a-Si) clusters that are spatially isolated.
The average size of the clusters decreases with the increasing oxygen concentration x in the films. The results indicate that
the structure of the present films can be described by a multi-shell model, which suggests that a-Si cluster is surrounded
in turn by the subshells of Si2O:H, SiO:H, Si2O3:H, and SiO2. 相似文献
46.
基于尼群地平在碱性条件下对铁氰化钾鲁米诺化学发光体系有较强的抑制作用,联用流动注射技术建立了测定尼群地平的新方法.本法的线形范围为0.1~100.0 μg/mL,检出限0.02 μg/mL ,此法用于尼群地平片剂含量测量和药典法对照结果满意. 相似文献
47.
郑州工程学院数理系 《数学物理学报(A辑)》2004,24(3):329-336
该文考虑一类新的非线性方程(|ut|r-2ut)t-Δutt-Δu-ρ(t)Δut=f(u) 的初边值问题,利用小扰动法证明了整体弱解的
存在性,借用位势井的概念得到了解的稳定性.〖HT5”H〗关键词:〖HT5”SS〗非线性发展方程;初边值问题;整体弱解;稳定性. 相似文献
48.
Suppose that the signal X to be estimated is a diffusion process in a random medium W and the signal is correlated with the observation noise. We study the historical filtering problem concerned with estimating the signal path up until the current time based upon the back observations. Using Dirichlet form theory, we introduce a filtering model for general rough signal X
W
and establish a multiple Wiener integrals representation for the unnormalized pathspace filtering process. Then, we construct a precise nonlinear filtering model for the process X itself and give the corresponding Wiener chaos decomposition. 相似文献
49.
本证明了当(a,b)不属于{(1,8),(2,4),(3,6),(4,4),(2s^2-s,2s^2 s))时,L^m(Ka,b)以谱为特征,其中a≤b,s≥2. 相似文献
50.