全文获取类型
收费全文 | 48609篇 |
免费 | 7408篇 |
国内免费 | 5345篇 |
专业分类
化学 | 25585篇 |
晶体学 | 536篇 |
力学 | 2227篇 |
综合类 | 257篇 |
数学 | 3975篇 |
物理学 | 13859篇 |
无线电 | 14923篇 |
出版年
2024年 | 171篇 |
2023年 | 1142篇 |
2022年 | 1533篇 |
2021年 | 1926篇 |
2020年 | 1862篇 |
2019年 | 1722篇 |
2018年 | 1569篇 |
2017年 | 1545篇 |
2016年 | 2120篇 |
2015年 | 2263篇 |
2014年 | 2680篇 |
2013年 | 3466篇 |
2012年 | 4346篇 |
2011年 | 4406篇 |
2010年 | 3181篇 |
2009年 | 3079篇 |
2008年 | 3337篇 |
2007年 | 3090篇 |
2006年 | 2779篇 |
2005年 | 2444篇 |
2004年 | 1683篇 |
2003年 | 1324篇 |
2002年 | 1258篇 |
2001年 | 959篇 |
2000年 | 927篇 |
1999年 | 983篇 |
1998年 | 801篇 |
1997年 | 723篇 |
1996年 | 732篇 |
1995年 | 600篇 |
1994年 | 481篇 |
1993年 | 393篇 |
1992年 | 370篇 |
1991年 | 304篇 |
1990年 | 238篇 |
1989年 | 178篇 |
1988年 | 128篇 |
1987年 | 129篇 |
1986年 | 111篇 |
1985年 | 105篇 |
1984年 | 67篇 |
1983年 | 50篇 |
1982年 | 42篇 |
1981年 | 26篇 |
1980年 | 15篇 |
1979年 | 14篇 |
1978年 | 8篇 |
1976年 | 9篇 |
1975年 | 11篇 |
1957年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
371.
Yuanyuan Li Jie Sun Li Wang Peng Zhan Zhishen Cao Zhenlin Wang 《Applied Physics A: Materials Science & Processing》2008,92(2):291-294
A sensor based on surface plasmon resonance (SPR) of plasmonic crystals fabricated via a colloidal-crystal-assisted templating
method is studied. Plasmonic crystals are prepared by depositing a thin gold (Au) layer onto a two-dimensional array of polystyrene
spheres self-assembled on a quartz substrate. The enhanced transmission as a result of the SPR of Au plasmonic crystals, which
are immersed in different ambient liquids, are measured and compared with that of polystyrene (PS) microsphere templates of
different sizes, both before and after removal of Au nanoprisms formed on the quartz substrate through pores among the spheres.
It is found that the measured sensitivities exhibit a linear dependence on the refractive index of the surrounding medium
and are linked to coupling effects between SPRs on the corrugated Au film and nanoislands. The feasibility of the SPR system
in molecular monolayer detection is further demonstrated through a formation of alkanethiolate self-assembled monolayers on
the Au film surface, which causes a 4 nm red-shift of the main SPR.
PACS 07.07.Df; 73.20.Mf; 78.66.-w; 81.16.Dn 相似文献
372.
Organic light-emitting diodes (OLEDs) based on the blend of two blue luminescent materials N,N′-bis(1-naphthyl)-N,N′-diphenyl-1,1′-diphenyl-4,4′-diamine (NPB) and 2-(4-biphenylyl)-5(4-tert-butyl-phenyl)-1,3,4-oxadiazole (PBD) were fabricated. The electroluminescence (EL) spectra of this device showed a new emission that is different from their intrinsic exciton emission. Compared with the photoluminescence (PL) spectra of single layer NPB and PBD, respectively, there was an apparent red shift in that of their blend. Thus the exciplex formation in the blend can be concluded due to the similar emission in both PL and EL spectra. The exciplex formation process and the effect of applied voltage were analyzed by Gaussian fitting. 相似文献
373.
Transmission behavior of light through a grating consisting of n-doped semiconductor with subwavelength slits under the application of external static magnetic fields is investigated. As dielectric constant of n-doped semiconductor can be substantially altered by applied magnetic field, in the Voigt configuration and for TM-polarized illumination, two transmission resonance peaks associated with localized waveguide modes of slits are significantly shifted toward the lower frequency regime with the increase of the applied magnetic field. These characteristics can be assigned to a reduction of effective plasma frequency of n-doped semiconductor under the applied magnetic field. Our findings may provide possibility for achieving tunable transmission resonance spectrum. 相似文献
374.
Hu Weijie Guo Bin Li Wenlong Wang Hongfei Wang Haojing 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(1):277-285
Journal of Radioanalytical and Nuclear Chemistry - To achieve the application of artificial plasma technology in high technology, the desorption behavior of cesium metals with low ionization... 相似文献
375.
Journal of Radioanalytical and Nuclear Chemistry - As a result of nuclear power plant accidents such as Chernobyl and Fukushima, and even their maintenance, the soil is contaminated due to the... 相似文献
376.
Li Bin Zhang Ying Ge Junyue Liu Kehui Li Ping 《Analytical and bioanalytical chemistry》2018,410(28):7449-7456
Analytical and Bioanalytical Chemistry - Appropriate sample preparation is pivotally important to obtain high-quality mass spectrometry imaging (MSI) data. Unlike mammalian tissues, preparation of... 相似文献
377.
378.
We observed a novel voltage peak in the proximity-induced superconducting gold (Au) nanowire while cooling the sample through the superconducting transition temperature. The voltage peak turned dip during warming. The voltage peak or dip was found to originate respectively from the emergence or vanishing of the proximity-induced superconductivity in the Au nanowire. The amplitude of the voltage signal depends on the temperature scanning rate, and it cannot be detected when the temperature is changed slower than 0.03 K/min. This transient feature suggests the non-equilibrium property of the effect. Ginzburg-Landau model clarified the voltage peak by considering the emergence of Cooper pairs of relatively lower free energy in superconducting W contact and the non-equilibrium diffusion of Cooper pairs and quasiparticles. 相似文献
379.
Prof. Dr. Shaodong Zhou Dr. Xiaoyan Sun Dr. Lei Yue Dr. Maria Schlangen Prof. Dr. Helmut Schwarz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(12):2967-2971
The thermal gas-phase reactions of [Al2VO5]+ and [AlV2O6]+ with methane have been explored by using Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry complemented by high-level quantum chemical calculations. Both cluster ions chemisorbed methane as the major reaction channels at room temperature. [Al2VO5]+ could break only one C−H bond to liberate CH3, whereas [AlV2O6]+ exhibited higher oxidizing ability such that it brings about the selective generation of formaldehyde. Mechanistic aspects are revealed and the crucial roles of the metal centers are discussed. 相似文献
380.
Dan-Li Hong Dr. Yang-Hui Luo Xiao-Tong He Zi-Yue Zheng Shan Su Jia-Ying Wang Cong Wang Chen Chen Prof. Bai-Wang Sun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(37):8805-8812
Precise revealing the mechanisms of excited-state intermolecular proton transfer (ESPT) and the corresponding geometrical relaxation upon photoexcitation and photoionization remains a formidable challenge. In this work, the compound (E)-4-(((4H-1,2,4-triazol-4-yl)imino)methyl)-2,6-dimethoxyphenol (TIMDP) adopting a D-π-A molecular architecture featuring a significant intramolecular charge transfer (ICT) effect has been designed. With the presence of perchloric acid (35 %), TIMDP can be dissolved through the formation of a HClO4–H2O–OH(TIMDP)–N(TIMDP) hydrogen-bonding bridge. At the ground state, the ICT effect is dominant, giving birth to crystals of TIMDP. Upon external stimuli (e.g., UV light irradiation, electro field), the excited state is achieved, which weakens the ICT effect, and significantly promotes the ESPT effect along the hydrogen-bonding bridge, resulting in crystals of [HTIMDP]+ ⋅ [H2O] ⋅ [ClO4]−. As a consequence, the mechanisms of the ESPT can be investigated, which distorted the D-π-A molecular architecture, tuned the emission color with the largest Stokes shift of 242 nm, and finally, high photoluminescence quantum yields (12 %) and long fluorescence lifetimes (8.6 μs) have achieved. These results not only provide new insight into ESPT mechanisms, but also open a new avenue for the design of efficient ESPT emitters. 相似文献