全文获取类型
收费全文 | 3317篇 |
免费 | 77篇 |
国内免费 | 14篇 |
专业分类
化学 | 2410篇 |
晶体学 | 50篇 |
力学 | 34篇 |
综合类 | 1篇 |
数学 | 135篇 |
物理学 | 778篇 |
出版年
2022年 | 15篇 |
2021年 | 21篇 |
2020年 | 27篇 |
2019年 | 40篇 |
2018年 | 30篇 |
2017年 | 23篇 |
2016年 | 47篇 |
2015年 | 48篇 |
2014年 | 70篇 |
2013年 | 184篇 |
2012年 | 104篇 |
2011年 | 143篇 |
2010年 | 78篇 |
2009年 | 95篇 |
2008年 | 181篇 |
2007年 | 163篇 |
2006年 | 180篇 |
2005年 | 171篇 |
2004年 | 197篇 |
2003年 | 154篇 |
2002年 | 124篇 |
2001年 | 74篇 |
2000年 | 52篇 |
1999年 | 56篇 |
1998年 | 42篇 |
1997年 | 36篇 |
1996年 | 49篇 |
1995年 | 57篇 |
1994年 | 41篇 |
1993年 | 31篇 |
1992年 | 60篇 |
1991年 | 54篇 |
1990年 | 40篇 |
1989年 | 42篇 |
1988年 | 38篇 |
1987年 | 41篇 |
1986年 | 39篇 |
1985年 | 53篇 |
1984年 | 48篇 |
1983年 | 30篇 |
1982年 | 47篇 |
1981年 | 38篇 |
1980年 | 42篇 |
1979年 | 35篇 |
1978年 | 33篇 |
1977年 | 29篇 |
1976年 | 23篇 |
1975年 | 24篇 |
1974年 | 25篇 |
1973年 | 27篇 |
排序方式: 共有3408条查询结果,搜索用时 31 毫秒
11.
12.
Hirohisa Yokota Kenji Kamoto Jun-ichi Igarashi Norihiko Mouri Yutaka Sasaki 《Optical Review》2002,9(1):9-12
A new configuration for an ASE reduction filter in EDFA repeaters for WDM optical transmission systems using optical fiber grating couplers (FGCs) was proposed and first demonstrated. The filtering characteristics of the proposed filter for amplified single wavelength signal and 2-channel WDM signals using EDFA were identified. It was found that the filter was effective to improve SNR in optical domain by reducing ASE noise. The required FGC characteristics for the filter were theoretically predicted under the condition that the total filter loss did not exceed 3 dB. More than 70% of drop efficiency was required in each FGC for the application of the proposed filter to an 8-channel WDM system using EDFA repeaters. 相似文献
13.
We study the inverse scattering problem for the nonlinear Schrödinger equation and for the nonlinear Klein–Gordon equation with the generalized Hartree type nonlinearity. We reconstruct the nonlinearity from knowledge of the scattering operator, which improves the known results. 相似文献
14.
The self-restoration properties in VWP networks are investigated with optimization about spare wavelength by simulations. Rapid restoration can be achieved by selection of rerouting path with long delay and no delay-limitation for new routes. 相似文献
15.
T. Mihara K. Miyamoto M. Kida T. Sasaki N. Aoki Y. Ochiai 《Superlattices and Microstructures》2003,34(3-6):383
A multiwall carbon nanotube crossroads has been fabricated by a manipulation technique using a glass microcapillary, and the low temperature transport properties investigated. The two-terminal conductance of an individual tube shows Tomonaga–Luttinger liquid behavior G∝Tα at high temperature and dI/dV ∝V α at low temperature. However, no evidence of such a power-law behavior is obtained in the four-terminal conductance at the junction, where the conductance shows an almost metallic behavior ‘corrected’ by weak localization. Weak localization would essentially appear in electron states at the junctions of MWNTs. 相似文献
16.
Kimihiko SatoTsutomu Kishimoto Minoru MorimotoHiroyuki Saimoto Yoshihiro Shigemasa 《Tetrahedron letters》2003,44(47):8623-8625
A simple method for the hydrolysis of acetals and ketals was accomplished in neutral water or aqueous media by hydrothermal treatment without using acidic reagents. The deacetalization reaction was effectively accelerated in the presence of calcium chloride. Because no acidic catalysts were employed, neutralization of the reaction mixture was not necessary after the reaction. This sequence was successfully applied to the hydrolysis of chitosan, a biodegradable polyaminosaccharide. 相似文献
17.
18.
19.
20.
The current status of the R & D activities is presented on electron beam processing of polymers being carried out at TRCRE. Topics included are sterilization of medical products, graft polymers for selective separation or absorbents and curing of liquid prepolymer-monomer systems. 相似文献