全文获取类型
收费全文 | 4919篇 |
免费 | 158篇 |
国内免费 | 13篇 |
专业分类
化学 | 3650篇 |
晶体学 | 79篇 |
力学 | 39篇 |
数学 | 187篇 |
物理学 | 1135篇 |
出版年
2023年 | 22篇 |
2022年 | 24篇 |
2021年 | 49篇 |
2020年 | 81篇 |
2019年 | 68篇 |
2018年 | 65篇 |
2017年 | 41篇 |
2016年 | 114篇 |
2015年 | 88篇 |
2014年 | 138篇 |
2013年 | 218篇 |
2012年 | 265篇 |
2011年 | 326篇 |
2010年 | 168篇 |
2009年 | 167篇 |
2008年 | 327篇 |
2007年 | 294篇 |
2006年 | 311篇 |
2005年 | 298篇 |
2004年 | 288篇 |
2003年 | 234篇 |
2002年 | 206篇 |
2001年 | 96篇 |
2000年 | 71篇 |
1999年 | 66篇 |
1998年 | 47篇 |
1997年 | 44篇 |
1996年 | 64篇 |
1995年 | 58篇 |
1994年 | 45篇 |
1993年 | 34篇 |
1992年 | 68篇 |
1991年 | 51篇 |
1990年 | 38篇 |
1989年 | 39篇 |
1988年 | 28篇 |
1987年 | 37篇 |
1986年 | 35篇 |
1985年 | 45篇 |
1984年 | 35篇 |
1983年 | 33篇 |
1982年 | 44篇 |
1981年 | 31篇 |
1980年 | 46篇 |
1979年 | 31篇 |
1978年 | 25篇 |
1977年 | 24篇 |
1975年 | 28篇 |
1974年 | 24篇 |
1973年 | 28篇 |
排序方式: 共有5090条查询结果,搜索用时 15 毫秒
21.
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
22.
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
23.
24.
25.
XPS measurement revealed that the original state of TiO2 was changed to Ti2O3 and TiO by ion bombardment. TiO2 decreased and Ti2O3 increased at the initial stage. TiO increased at a later stage than Ti2O3. Each of them saturated after enough sputtering time.A formulation was proposed in order to explain the change of XPS spectra for oxides as a function of ion sputtering time. This formulation was based on reaction equations that contain two reduction processes (from TiO2 to Ti2O3 and from Ti2O3 to TiO), and sputtering effects. Using four fitting parameters (two reduction coefficients, sputtering yield and information depth), the present formula was fitted to the experimental results. The fitting results agree satisfactorily with the experimental results. The calculation shows that the reduction coefficient from TiO2 to Ti2O3 is about ten times larger than that from Ti2O3 to TiO. This calculation predicts that surface composition of an oxide that is changed by ion bombardment will reach a different value depending on its bulk composition. Moreover, the present formulation can determine the chemical states of compounds changed by ion bombardment. 相似文献
26.
Naoki Miyamoto Shusuke Nisiyama Satoshi Tomioka Takeaki Enoto 《Optics Communications》2007,272(1):67-72
We utilize nitroanisole, that absorbs infrared (IR) radiation as heat, as an optical modulation device based on a thermal process. The nitroanisole exhibits a thermal lens effect, i.e. a temperature dependent refractive index. Hence, the nitroanisole can induce phase modulation to visible light, in direct response to intensity of the incident IR radiation. The proposed method can be used to obtain the phase modulation distribution that corresponds to the IR intensity distribution, i.e. the IR hologram itself, on the nitroanisole by examining the phase map of visible light that is modulated upon passing through the nitroanisole. The IR wavefront can be reconstructed by calculating extracted IR holograms through the Fresnel transform. It is verified that both the amplitude and the phase of the IR wavefront can be reconstructed accurately by proposed method. 相似文献
27.
28.
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
29.
30.