全文获取类型
收费全文 | 8069篇 |
免费 | 305篇 |
国内免费 | 53篇 |
专业分类
化学 | 5612篇 |
晶体学 | 71篇 |
力学 | 191篇 |
综合类 | 1篇 |
数学 | 941篇 |
物理学 | 1053篇 |
无线电 | 558篇 |
出版年
2023年 | 68篇 |
2022年 | 79篇 |
2021年 | 168篇 |
2020年 | 161篇 |
2019年 | 136篇 |
2018年 | 107篇 |
2017年 | 99篇 |
2016年 | 223篇 |
2015年 | 198篇 |
2014年 | 244篇 |
2013年 | 407篇 |
2012年 | 567篇 |
2011年 | 601篇 |
2010年 | 348篇 |
2009年 | 277篇 |
2008年 | 519篇 |
2007年 | 538篇 |
2006年 | 548篇 |
2005年 | 528篇 |
2004年 | 442篇 |
2003年 | 368篇 |
2002年 | 291篇 |
2001年 | 112篇 |
2000年 | 86篇 |
1999年 | 75篇 |
1998年 | 72篇 |
1997年 | 90篇 |
1996年 | 127篇 |
1995年 | 67篇 |
1994年 | 75篇 |
1993年 | 68篇 |
1992年 | 50篇 |
1991年 | 36篇 |
1990年 | 27篇 |
1989年 | 32篇 |
1988年 | 42篇 |
1987年 | 26篇 |
1986年 | 34篇 |
1985年 | 67篇 |
1984年 | 45篇 |
1983年 | 26篇 |
1982年 | 52篇 |
1981年 | 30篇 |
1980年 | 25篇 |
1979年 | 26篇 |
1978年 | 34篇 |
1977年 | 29篇 |
1976年 | 22篇 |
1975年 | 21篇 |
1974年 | 22篇 |
排序方式: 共有8427条查询结果,搜索用时 9 毫秒
71.
Jonathan Breuer Eric Ryckman Barry Simon 《Communications in Mathematical Physics》2010,295(2):531-550
For full-line Jacobi matrices, Schrödinger operators, and CMV matrices, we show that being reflectionless, in the sense of the well-known property of m-functions, is equivalent to a lack of reflection in the dynamics in the sense that any state that goes entirely to x = ?∞ as t → ?∞ goes entirely to x = ∞ as t → ∞. This allows us to settle a conjecture of Deift and Simon from 1983 regarding ergodic Jacobi matrices. 相似文献
72.
73.
74.
75.
The preparation of cobalt nano-particles from a solution of Co(CO)3(NO) in n-decane under ultrasonication with a frequency of 20 kHz yielded cobalt particles of a size of ca. 5 nm. The presence of either silica or oleic acid in the solution reduced the particle size to ca. 3 and 2 nm, respectively. The resulting particle size is independent of the ultrasonication time, initial Co(CO)3(NO) concentration, ultrasound intensity and solution temperature. It is postulated that bubble collapse generates multiple nucleation sites resulting in the formation of cobalt particles with a rather uniform particle size distribution. 相似文献
76.
Arijit Das Eric Soehnlen Stephan Woods Ravi Hegde Amanda Henry Arne Gericke Soumitra Basu 《Journal of nanoparticle research》2011,13(12):6283-6290
We report a novel gold nanobioconjugate system that achieves targeted delivery of the small molecule drug doxorubicin to endothelial
cells using anti-VEGFR-2 antibody conjugated gold nanoparticles (GNPs). The reported nanobioconjugate system combines the
inherent ability of GNPs to undergo high levels of derivatization with the precision of antibody recognition of a cell surface
antigen. Transmission electron microscopy (TEM) and surface-enhanced Raman spectroscopy (SERS) confirmed intracellular presence
of the GNPs. Using a VEGFR-2 expressing cell line and a cell line that is negative for the receptor, in combination with competition
assay we established the cell specific targeted delivery of the nanobioconjugate. The nanobioconjugate system described here
may have potential drug delivery applications for antiangiogenic cancer therapy. 相似文献
77.
A comparative study of the luminescent properties of Y2O3:Eu3+ phosphor powders and thin films sputtered from targets prepared from combustion synthesized powders is reported. Thin films of (Y0.96Eu0.04)2O3 were deposited on silicon substrates. Films deposited at 600 °C had both monoclinic and cubic phases of Y2O3, which developed to an oriented cubic phase after annealing. Films and powders showed a linear dependence of the intensity of the 5D7→7F2 (611 nm) transition with temperature in the range 26-660 °C with an average rate of change of 1.8×10−4 °C−1. The rate of change appears to be dependent on the Eu3+ concentration. This work shows that these thin films can be used as thermographic phosphors for remote temperature measurements. 相似文献
78.
Eric Jourdanneau Tony Gabard Frdric Chaussard Robert Saint-Loup Hubert Berger Elena Bertseva Frdric Grisch 《Journal of Molecular Spectroscopy》2007,246(2):167-179
CARS laboratory experiments were done in the 2905–2925 cm−1 range, in the vicinity of the ν1 band of the methane molecule, for pressures ranging from 1 to 50 bar, and temperatures up to 1100 K. These experiments were carried out in order to retrieve the pressure evolution of the CH4 spectrum, as well as to confirm its temperature dependance. After a brief recall on the theory used to compute pressure broadening coefficients and relaxation rates, we consider the ν3 and ν4 infrared bands of methane for benchmark calculations purposes. Next, we present recent experimental CARS spectra and calculated ones. Lastly, we discuss flame experiments as well as comparisons of temperature retrieval using N2 and CH4 as probe molecules. 相似文献
79.
Margriet V. D. Z. Park Iseult Lynch Sonia Ram��rez-Garc��a Kenneth A. Dawson Liset de la Fonteyne Eric Gremmer Wout Slob Jacob J. Bried�� Andreas Elsaesser C. Vyvyan Howard Henk van Loveren Wim H. de Jong 《Journal of nanoparticle research》2011,13(12):6775-6787
The biological response to four well-characterized amorphous silica nanoparticles was investigated in RAW 264.7 macrophages in view of their potential application as drug carriers to sites of inflammation. All silica nanoparticles-induced cell membrane damage, reduced metabolic activity, generated ROS and released various cytokines, but to different extents. Two silica nanoparticles of 34 nm (A and B) with different zetapotentials were more cytotoxic than (aggregated) 11 and 248 nm nanoparticles, while cytokines were mostly induced by the (aggregated) 11 nm and only one of the 34 nm nanoparticles (34A). The results indicate that specific silica nanoparticles may have counterproductive effects, for example when used as carriers of anti-inflammatory drugs. The physicochemical properties determining the response of nanoparticles vary for different responses, implying that a screening approach for the safe development of nanoparticles needs to consider the role of combinations of (dynamic) physicochemical properties and needs to include multiple toxicity endpoints. 相似文献
80.
Peter Kop?anský Martina Koneracká Vlasta Závišová Katalin Fodor-Csorba Anikó Vajda Eric Beaugnon 《Journal of magnetism and magnetic materials》2010,322(22):3696-3700
The studied ferronematic is a nematic liquid crystal (ZLI1695) of low negative anisotropy of the diamagnetic susceptibility (χa<0) doped with the magnetic particles Fe3O4. Structural instabilities are interpreted within Burylov and Raikher's theory. The high magnetic fields were oriented perpendicular (Freedericksz transition) or parallel to the initial director. Using capacitance measurements the Freedericksz threshold magnetic field of the ferronematic BFN, and the critical magnetic field Bmax, at which the initial parallel orientation between the director and the magnetic moment of magnetic particles breaks down, have been determined. The values of these quantities have been used to estimate the surface density of the anchoring energy W of liquid crystal molecules on the surface of the magnetic particles. The obtained values indicate a soft anchoring of the liquid crystal on the magnetic particles with a preferred parallel orientation of the magnetic moment of magnetic particles and the director. 相似文献