全文获取类型
收费全文 | 3642篇 |
免费 | 114篇 |
国内免费 | 16篇 |
专业分类
化学 | 2753篇 |
晶体学 | 38篇 |
力学 | 57篇 |
数学 | 197篇 |
物理学 | 727篇 |
出版年
2022年 | 26篇 |
2021年 | 30篇 |
2020年 | 50篇 |
2019年 | 61篇 |
2018年 | 42篇 |
2017年 | 20篇 |
2016年 | 69篇 |
2015年 | 47篇 |
2014年 | 68篇 |
2013年 | 157篇 |
2012年 | 158篇 |
2011年 | 225篇 |
2010年 | 96篇 |
2009年 | 118篇 |
2008年 | 199篇 |
2007年 | 209篇 |
2006年 | 225篇 |
2005年 | 210篇 |
2004年 | 178篇 |
2003年 | 142篇 |
2002年 | 142篇 |
2001年 | 76篇 |
2000年 | 62篇 |
1999年 | 60篇 |
1998年 | 40篇 |
1997年 | 41篇 |
1996年 | 56篇 |
1995年 | 53篇 |
1994年 | 31篇 |
1993年 | 38篇 |
1992年 | 47篇 |
1991年 | 33篇 |
1990年 | 33篇 |
1989年 | 37篇 |
1988年 | 49篇 |
1987年 | 37篇 |
1986年 | 35篇 |
1985年 | 70篇 |
1984年 | 45篇 |
1983年 | 34篇 |
1982年 | 35篇 |
1981年 | 39篇 |
1980年 | 35篇 |
1979年 | 47篇 |
1978年 | 36篇 |
1977年 | 31篇 |
1976年 | 22篇 |
1975年 | 28篇 |
1974年 | 34篇 |
1973年 | 27篇 |
排序方式: 共有3772条查询结果,搜索用时 234 毫秒
11.
The electronic states of the Cr overlayers on TiO2(0 0 1) surfaces have been investigated using angle-resolved and resonant photoemission spectroscopy with synchrotron radiation. At lower coverages, Cr deposition on TiO2(0 0 1) creates two well separated in-gap emissions due to the formation of surface Ti3+ (3d1) ions and Cr3+ (3d3) ions. At higher coverages, the in-gap emission is developed into the 2-peak-structure emission of Cr 3d character. The corresponding state is considered to be of metallic nature from the viewpoint of the high ability of oxygen adsorption, but has no Fermi edge, indicating a possibility of forming small Cr clusters on TiO2(0 0 1) at this stage. 相似文献
12.
Masanori Asakura 《K-Theory》2002,27(3):273-280
We construct 0-cycles on a self-product of a curve whose cycle classes are linearly independent in the extension group of arithmetic Hodge structure. This is an extended version of Theorem 4.5 of Asakura's contribution to CMR Lecture Notes Ser. 24 ((2000), pp. 133–154). 相似文献
13.
14.
15.
Ryuhei Wakita Masanori Miyakoshi Yohji Nakatsuji Mitsuo Okahara 《Journal of inclusion phenomena and macrocyclic chemistry》1991,10(1):127-139
A series of noncyclic neutral ionophores has been synthesized by the reaction of oligoethylene glycol dihalides with 8-quinolinol. Complexation properties for alkali metal picrates were evaluated from solvent extraction and bulk liquid membrane transport experiments. Complexation profiles of the newly synthesized ionophores with a hexyl chain were similar to those of their homologues without the hexyl chain in the extraction experiments. Among them, the pentaethylene glycol derivatives showed the highest extraction efficiency and selectivity towards potassium ion. From the1H NMR spectra (400 MHz), the change in chemical shifts of the aromatic protons upon the addition of alkali metal thiocyanates suggested the existence of a stabilization effect which is caused by intramolecular stacking conformations between the quinoline rings during complexation. Aryl stacking interactions depend on the size of the cations and on the chain length of the oligoethylene glycol. The relationship between transport ability towards alkali metal cations and lipophilicity of these ionophores is also discussed. 相似文献
16.
17.
18.
V. P. Ladygin T. Uesaka T. Saito M. Hatano A. Yu. Isupov H. Kato N. B. Ladygina Y. Maeda A. I. Malakhov J. Nishikawa T. Ohnishi H. Okamura S. G. Reznikov H. Sakai N. Sakamoto S. Sakoda Y. Satou K. Sekiguchi K. Suda A. Tamii N. Uchigashima K. Yako 《Physics of Atomic Nuclei》2006,69(8):1271-1278
RIKEN Accelerator Research Facility data on the tensor analyzing power T 20 of the dd → 3Hen and dd → 3Hp reactions at zero angle for deuteron kinetic energies of 140, 200, and 270 MeV are reported. The observed positive sign of T 20 clearly demonstrates the sensitivity to the D/S-wave ratio in the 3He and 3H wave functions in the energy range of the experiment. Data on T 20 for the 3Hen channel are in agreement with those for the 3Hp channel within the experimental errors. 相似文献
19.
Makoto Kato Azusa Tsukigase Hiromitsu Tanaka Arimitsu Usuki Isamu Inai 《Journal of polymer science. Part A, Polymer chemistry》2006,44(3):1182-1188
Isobutylene isoprene rubber (IIR)‐clay nanocomposites have been prepared successfully by melt intercalation with maleic anhydride‐grafted IIR (Ma‐g‐IIR) and organophilic clay. In IIR‐clay nanocomposites, the silicate layers of the clay were exfoliated and dispersed into the monolayer. The nanocomposites exhibited greater gas barrier properties compared with those of Ma‐g‐IIR. When 15 phr clay was added, gas barrier properties were 2.5 times greater than those of Ma‐g‐IIR. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1182–1188, 2006 相似文献
20.
Weighted Strichartz estimates with homogeneous weights with critical exponents are proved for the wave equation without a support restriction on the forcing term. The method of proof is based on expansion by spherical harmonics and on the Sobolev space over the unit sphere, by which the required estimates are reduced to the radial case. As an application of the weighted Strichartz estimates, the existence and uniqueness of self‐similar solutions to nonlinear wave equations are proved on up to five space dimensions. © 2006 Wiley Periodicals, Inc. 相似文献