全文获取类型
收费全文 | 2021篇 |
免费 | 56篇 |
国内免费 | 61篇 |
专业分类
化学 | 1322篇 |
晶体学 | 11篇 |
力学 | 91篇 |
综合类 | 1篇 |
数学 | 268篇 |
物理学 | 445篇 |
出版年
2023年 | 25篇 |
2022年 | 27篇 |
2021年 | 45篇 |
2020年 | 76篇 |
2019年 | 37篇 |
2018年 | 34篇 |
2017年 | 37篇 |
2016年 | 51篇 |
2015年 | 33篇 |
2014年 | 35篇 |
2013年 | 92篇 |
2012年 | 70篇 |
2011年 | 101篇 |
2010年 | 61篇 |
2009年 | 47篇 |
2008年 | 68篇 |
2007年 | 89篇 |
2006年 | 68篇 |
2005年 | 80篇 |
2004年 | 68篇 |
2003年 | 53篇 |
2002年 | 55篇 |
2001年 | 37篇 |
2000年 | 40篇 |
1999年 | 44篇 |
1998年 | 17篇 |
1997年 | 27篇 |
1996年 | 38篇 |
1995年 | 23篇 |
1994年 | 27篇 |
1993年 | 40篇 |
1992年 | 22篇 |
1991年 | 26篇 |
1990年 | 33篇 |
1989年 | 24篇 |
1988年 | 23篇 |
1987年 | 24篇 |
1986年 | 23篇 |
1985年 | 32篇 |
1984年 | 40篇 |
1983年 | 22篇 |
1982年 | 24篇 |
1981年 | 27篇 |
1980年 | 20篇 |
1979年 | 30篇 |
1978年 | 17篇 |
1977年 | 26篇 |
1976年 | 18篇 |
1975年 | 23篇 |
1972年 | 18篇 |
排序方式: 共有2138条查询结果,搜索用时 15 毫秒
1.
Paired single residue‐transposed Lys‐N and Lys‐C digestions for label‐free identification of N‐terminal and C‐terminal MS/MS peptide product ions: ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry and tandem mass spectrometry for peptide de novo sequencing
下载免费PDF全文
![点击此处可从《Rapid communications in mass spectrometry : RCM》网站下载免费的PDF全文](/ch/ext_images/free.gif)
2.
Alexander J. Marshall 《Analytica chimica acta》2004,527(1):13-20
Holographic sensors for monitoring ionic strength have been fabricated from charged sulphonate and quaternary ammonium monomers, incorporated into thin, polymeric hydrogel films which were transformed into volume holograms. The diffraction wavelength or reflected colour of the holograms was used to characterise their swelling or de-swelling behaviour as a function of ionic strength in various media. The effects of co-monomer structure, buffer composition, ion composition, pH and temperature were evaluated, whilst the reversibility and reproducibility of the sensor was also assessed. An acrylamide-based hologram containing equal molar amounts of negatively and positively charged monomers was shown to be able to quantify ionic strength independent of the identity of the ionic species present in the test solution. The sensor was fully reversible, free of hysteresis and exhibited little response to pH between 3 and 9 and temperature within the range 20-45 °C. The system was successfully used to quantify the ionic strength of milk solutions, which contain a complex mixture of ions and biological components. 相似文献
3.
4.
David S. McGuinness Edward L. Marshall Vernon C. Gibson Jonathan W. Steed 《Journal of polymer science. Part A, Polymer chemistry》2003,41(23):3798-3803
Hetero‐bimetallic Fe(II) alkoxide/aryloxides were evaluated as initiators for the ring‐opening polymerization of rac‐lactide. [(THF)NaFe(OtBu)3]2 ( 1 ) and [(THF)4Na2Fe(2,6‐diisopropylphenolate)4] ( 2 ) (THF = tetrahydrofuran) both polymerized lactide efficiently at room temperature, with complex 1 affording better control over the molecular weight parameters of the resultant polymer. At conversions below 70%, a linear increase in molecular weight with conversion was observed, indicative of a well‐controlled polymerization process. Complex 2 is the first example of a dianionic Fe(II) alkoxide and has been structurally characterized to reveal a distorted square planar FeO4 array in which both Na counterions bridge two aryloxide ligands and are further complexed by two THF ligands. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3798–3803, 2003 相似文献
5.
6.
7.
M. Gutowski I. Dabkowska J. Rak S. Xu J.M. Nilles D. Radisic K.H. Bowen Jr 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):431-439
The photoelectron spectra (PES) of anions of uracil-glycine and uracil-phenylalanine complexes reveal broad features with
maxima at 1.8 and 2.0 eV. The results of ab initio density functional B3LYP and second order M?ller-Plesset theory calculations indicate that the excess electron occupies a
π* orbital localized on uracil. The excess electron attachment to the complex can induce a barrier-free proton transfer (BFPT)
from the carboxylic group of glycine to the O8 atom of uracil. As a result, the four most stable structures of the anion of
uracil-glycine complex can be characterized as the neutral radical of hydrogenated uracil solvated by the anion of deprotonated
glycine. The similarity between the PES spectra for the uracil complexes with glycine and phenylalanine suggests that the
BFPT is also operative in the case of the latter anionic species. The BFPT to the O8 atom of uracil may be related to the
damage of nucleic acid bases by low energy electrons because the O8 atom is involved in a hydrogen bond with adenine in the
standard Watson-Crick pairing scheme.
Received 6 April 2002 Published online 13 September 2002 相似文献
8.
9.
Abstract In [16] a visco-elastic relaxation system, called the relaxed Burnett system, was proposed by Jinand Slemrod as a moment approximation to the Boltzmann equation. The relaxed Burnett system is weaklyparabolic, has a linearly hyperbolic convection part, and is endowed with a generalized eotropy inequality. Itagrees with the solution of the Boltzmann equation up to the Burnett order via the Chapman-Enskog expansion. We develop a one-dimensional non-oscillatory numerical scheme based on the relaxed Burnett system forthe Boltzmann equation. We compare numerical results for stationary shocks based on this relaxation scheme,and those obtained by the DSMC (Direct Simulation Monte Carlo), by the Navier-Stokes equations and bythe extended thermodynamics with thirteen moments (the Grad equations). Our numerical experiments showthat the relaxed Burnett gives more accurate approximations to the shock profiles of the Boltzmann equationobtained by the DSMC, for a range of Mach numbers for hypersonic flows, th 相似文献
10.