全文获取类型
收费全文 | 9392篇 |
免费 | 603篇 |
国内免费 | 712篇 |
专业分类
化学 | 809篇 |
晶体学 | 16篇 |
力学 | 374篇 |
综合类 | 128篇 |
数学 | 2921篇 |
物理学 | 1322篇 |
综合类 | 5137篇 |
出版年
2024年 | 13篇 |
2023年 | 65篇 |
2022年 | 131篇 |
2021年 | 157篇 |
2020年 | 177篇 |
2019年 | 188篇 |
2018年 | 171篇 |
2017年 | 228篇 |
2016年 | 226篇 |
2015年 | 203篇 |
2014年 | 424篇 |
2013年 | 508篇 |
2012年 | 518篇 |
2011年 | 494篇 |
2010年 | 423篇 |
2009年 | 551篇 |
2008年 | 560篇 |
2007年 | 621篇 |
2006年 | 555篇 |
2005年 | 488篇 |
2004年 | 477篇 |
2003年 | 420篇 |
2002年 | 407篇 |
2001年 | 340篇 |
2000年 | 305篇 |
1999年 | 268篇 |
1998年 | 229篇 |
1997年 | 219篇 |
1996年 | 189篇 |
1995年 | 168篇 |
1994年 | 157篇 |
1993年 | 160篇 |
1992年 | 101篇 |
1991年 | 105篇 |
1990年 | 97篇 |
1989年 | 95篇 |
1988年 | 67篇 |
1987年 | 47篇 |
1986年 | 26篇 |
1985年 | 24篇 |
1984年 | 16篇 |
1983年 | 9篇 |
1982年 | 15篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 12篇 |
1978年 | 8篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1974年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
ZHANG Shu-min 《数学季刊》2004,(2)
In the paper, we prove that the complement of Tm(1,4,m - 6)(m > 10) is chromatically unique if and only if m ≠5k(k ≥ 2). 相似文献
92.
采用基于相对论平均场的耦合常数解析延拓方法研究球形核的单粒子共振态.具体计算了Zr同位素链中巨晕核的核芯核122Zr阈值附近的中子共振态的能量、宽度和波函数,其结果同相应的散射相移法的结果一致. Using analytic continuation in the coupling constant (ACCC) method within the framework of the self-consistent relativistic mean field (RMF) theory, the energies, widths and wave functions for single-particle resonant states close to the continuum threshold are evaluated. Predictions are also compared with corresponding results obtained by the scattering phase shift method. 相似文献
93.
A time‐marching formulation is derived from the space–time integrated least squares (STILS) method for solving a pure hyperbolic convection equation and is numerically compared to various known methods. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
94.
在误差序列为Lqmixingale情形下,给出了半参数回归模型中β和g(t)估计,研究了估计量的q阶平均相合性在较一般的条件下,得到了理想的结果 相似文献
95.
We propose a minimum mean absolute error linear interpolator (MMAELI), based on theL
1 approach. A linear functional of the observed time series due to non-normal innovations is derived. The solution equation
for the coefficients of this linear functional is established in terms of the innovation series. It is found that information
implied in the innovation series is useful for the interpolation of missing values. The MMAELIs of the AR(1) model with innovations
following mixed normal andt distributions are studied in detail. The MMAELI also approximates the minimum mean squared error linear interpolator (MMSELI)
well in mean squared error but outperforms the MMSELI in mean absolute error. An application to a real series is presented.
Extensions to the general ARMA model and other time series models are discussed.
This research was supported by a CityU Research Grant and Natural Science Foundation of China. 相似文献
96.
In this paper,the authors obtain the Backlund transformation on time-like surfaces with constant mean curvature in R2,1.Using this transformation,families of surfaces with constant mean curvature from known ones can be constructed. 相似文献
97.
Transmission fluctuation spectrometry (TFS) is a method for the analysis of particle size distributions based on the statistical fluctuations of a transmission signal. Complete information on the PSD and particle concentration can be retrieved by a special transformation of the transmission signal, whereby the expectancy of the transmission square (ETS) is determined after the signal has been subjected to a procedure of spatial and temporal averaging. By varying the averaging parameters over a wide range, a spectrum of ETSs is obtained and introduced into a linear equation system, which yields the PSD. In the experimental realization presented here, variable temporal averaging is realized in the frequency domain with a series of low pass filters at different cutoff frequencies while spatial averaging inevitably occurs as the particles pass through a focused Gaussian beam of finite cross section. Experimental results on spherical particles (glass beads) and non‐spherical particles (SiC) are presented. The PSDs are resolved in 30 intervals within a particle size range from 1–1000 μm, employing a modified Chahine inversion algorithm. So far, the measurements are limited to moderate particle concentrations. Some influences affecting the measurements, especially for higher particle concentrations, are discussed in detail. 相似文献
98.
99.
Yuzo Maruyama 《Journal of multivariate analysis》2004,88(2):320-334
We consider estimation of a multivariate normal mean vector under sum of squared error loss.We propose a new class of minimax admissible estimator which are generalized Bayes with respect to a prior distribution which is a mixture of a point prior at the origin and a continuous hierarchical type prior. We also study conditions under which these generalized Bayes minimax estimators improve on the James–Stein estimator and on the positive-part James–Stein estimator. 相似文献
100.