全文获取类型
收费全文 | 16812篇 |
免费 | 595篇 |
国内免费 | 54篇 |
专业分类
化学 | 13439篇 |
晶体学 | 85篇 |
力学 | 264篇 |
数学 | 2000篇 |
物理学 | 1673篇 |
出版年
2023年 | 112篇 |
2022年 | 509篇 |
2021年 | 609篇 |
2020年 | 363篇 |
2019年 | 415篇 |
2018年 | 315篇 |
2017年 | 246篇 |
2016年 | 554篇 |
2015年 | 550篇 |
2014年 | 541篇 |
2013年 | 1051篇 |
2012年 | 1099篇 |
2011年 | 1264篇 |
2010年 | 759篇 |
2009年 | 747篇 |
2008年 | 1082篇 |
2007年 | 991篇 |
2006年 | 887篇 |
2005年 | 832篇 |
2004年 | 682篇 |
2003年 | 563篇 |
2002年 | 546篇 |
2001年 | 203篇 |
2000年 | 177篇 |
1999年 | 138篇 |
1998年 | 139篇 |
1997年 | 130篇 |
1996年 | 161篇 |
1995年 | 99篇 |
1994年 | 102篇 |
1993年 | 97篇 |
1992年 | 82篇 |
1991年 | 95篇 |
1990年 | 80篇 |
1989年 | 96篇 |
1988年 | 78篇 |
1987年 | 72篇 |
1986年 | 66篇 |
1985年 | 77篇 |
1984年 | 94篇 |
1983年 | 48篇 |
1982年 | 84篇 |
1981年 | 67篇 |
1980年 | 58篇 |
1979年 | 51篇 |
1978年 | 59篇 |
1977年 | 46篇 |
1976年 | 37篇 |
1975年 | 28篇 |
1963年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
In this paper the derivatives of the solution of an initial boundary value problem for a nonlinear uniformly parabolic equation in the interior with the total variation of the boundary data and the L∞-norm of the initial condition are estimated. 相似文献
82.
Cristian Barbarosie Anca‐Maria Toader 《Mathematical Methods in the Applied Sciences》2005,28(9):1089-1114
We prove bounds on the homogenized coefficients for general non‐periodic mixtures of an arbitrary number of isotropic materials, in the heat conduction framework. The component materials and their proportions are given through the Young measure associated to the sequence of coefficient functions. Upper and lower bounds inequalities are deduced in terms of algebraic relations between this Young measure and the eigenvalues of the H‐limit matrix. The proofs employ arguments of compensated compactness and fine properties of Young measures. When restricted to the periodic case, we recover known bounds. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
83.
84.
3-Hydroxybutyramides are obtained in high optical yield from ethyl (±)-3-hydroxybutyrate and aliphatic amines when the reaction is catalyzed by Candida antartica lipase. The chemical reduction of these 3-hydroxybutyramides yields the corresponding 1,3 -aminoalcohols. 相似文献
85.
Maria Alberich-Carramiñana 《Advances in Mathematics》2007,216(2):753-770
Given a birational normal extension O of a two-dimensional local regular ring (R,m), we describe all the equisingularity types of the complete m-primary ideals J in R whose blowing-up X=BlJ(R) has some point Q whose local ring OX,Q is analytically isomorphic to O. 相似文献
86.
P. Bonville M. Rams K. Królas J.-P. Sanchez P. C. Canfield O. Trovarelli C. Geibel 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,55(1):77-84
We have examined the magnetic properties of the heavy electron compounds
YbAgGe and YbPtIn by 170Yb M?ssbauer spectroscopy down to 0.1 K, and
the crystal field properties of YbAgGe by Perturbed Angular Correlations
(PAC) measurements up to 900 K. In YbAgGe, we show that each of the two
magnetically ordered phases below 0.8 K involves a specific incommensurate
modulation of the Yb moment. An analysis of existing low temperature specific
heat data suggests the
persistence of fluctuations of the correlated Yb spins down to 0.1 K.
The PAC data allow to discriminate among proposed Yb3+ crystal field
level schemes. In YbPtIn, we show that the low temperature magnetic order
phase has an antiferro-para structure, where zero moment Yb ions coexist with
large moment ones, and that a 90° moment reorientation occurs at
1.4 K. 相似文献
87.
E. Maria Claesson Nilesh C. Mehendale Robertus J.M. Klein Gebbink Gerard van Koten Albert P. Philipse 《Journal of magnetism and magnetic materials》2007
Monodisperse magnetizable colloidal silica particles in a stable dispersion have been functionalized with a homogeneous catalyst: a PCP–pincer Pd-complex. In a proof-of-principle experiment we demonstrate the catalytic activity of the colloids in a C–C bond formation reaction. Advantages of the magnetic silica carriers are the large surface-to-volume ratio and the easy recovery by magnetic separation. After magnetic separation, the catalyst-loaded particles are readily redispersed for further use. 相似文献
88.
89.
90.
Giovanni Bruno Maria M. Giangregorio April S. Brown Soojeong Choi 《Applied Surface Science》2006,253(1):219-223
GaN is grown on Si-face 4H-SiC(0 0 0 1) substrates using remote plasma-assisted methods including metalorganic chemical vapour deposition (RP-MOCVD) and molecular beam epitaxy (MBE). Real time spectroscopic ellipsometry is used for monitoring all the steps of substrate pre-treatments and the heteroepitaxial growth of GaN on SiC. Our characterization emphasis is on understanding the nucleation mechanism and the GaN growth mode, which depend on the SiC surface preparation. 相似文献