全文获取类型
收费全文 | 379篇 |
免费 | 16篇 |
国内免费 | 2篇 |
专业分类
化学 | 193篇 |
晶体学 | 7篇 |
力学 | 14篇 |
数学 | 119篇 |
物理学 | 64篇 |
出版年
2023年 | 1篇 |
2022年 | 12篇 |
2021年 | 15篇 |
2020年 | 8篇 |
2019年 | 10篇 |
2018年 | 7篇 |
2017年 | 13篇 |
2016年 | 16篇 |
2015年 | 17篇 |
2014年 | 18篇 |
2013年 | 37篇 |
2012年 | 29篇 |
2011年 | 23篇 |
2010年 | 21篇 |
2009年 | 26篇 |
2008年 | 18篇 |
2007年 | 16篇 |
2006年 | 12篇 |
2005年 | 14篇 |
2004年 | 9篇 |
2003年 | 8篇 |
2002年 | 8篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1979年 | 2篇 |
1977年 | 4篇 |
1975年 | 3篇 |
1973年 | 2篇 |
1961年 | 1篇 |
排序方式: 共有397条查询结果,搜索用时 31 毫秒
391.
The purpose of this Note is to provide the rate of strong consistency for a nonparametric estimator of entropy under random censorship. We also establish an uniform-in-bandwidth consistency for this estimator. To cite this article: S. Bouzebda, I. Elhattab, C. R. Acad. Sci. Paris, Ser. I 347 (2009). 相似文献
392.
We consider the following nonlinear viscoelastic equation together with Dirichlet-boundary conditions, in a bounded domain Ω and ρ > 0. We prove an exponential decay result for a class of relaxation functions. Our result is established without imposing the usual relation between g and its derivative (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
393.
We present surface‐enhanced Raman scattering (SERS) spectra of the RNA nucleosides adenosine, cytidine, guanosine and uracil and the methylated derivatives 5‐methylcytidine and 7‐methylguanosine, a class of important nucleic acid components that has not previously been well characterised using SERS spectroscopy. Our work shows that the selection of aggregating agent plays a crucial role for SERS analysis of these nucleosides with K2SO4 generating immediate enhancement while NaCl only gave immediate enhancement for the pyrimidine nucleosides. The SERS spectra contain a number of marker bands that are highly sensitive to structural differences between these nucleosides, in particular methylation, and at lower concentration ranges than are possible for conventional Raman scattering. Finally, spectral analyses and assignments of the vibrational modes responsible for these marker bands are also presented, and the effect of the aggregating agent on these modes is discussed in terms of interactions between each nucleoside and the metal surface. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
394.
A sensitive time- resolved luminescence method for the determination of meloxicam (MX) in methanol and in aqueous solution
is described. The method is based on the luminescence sensitization of europium (Eu3+) by formation of ternary complex with MX in the presence of 1,10- phenanthroline as coligand, Tween-80 as surfactant and
gadolinium ion as a co-luminescence reagent. The signal for Eu- MX-1, 10- phenanthroline is monitored at λex = 360 nm and λem = 620 nm. Optimum conditions for the formation of the complex in aqueous system were 0.01 M TRIS buffer, pH 8.0, 1,10- phenanthroline
(6.0 × 10−6 M) , Gd3+ (7.0 × 10−6 M), Tween-80 (0.28%) and 1.75 mM of Eu3+ which allows the determination of 20–800 ppb of MX with limit of detection (LOD) of 7 ppb. The relative standard deviations
of the method range between 0.1 and 1.1% indicating excellent reproducibility of the method. The proposed method was successfully
applied for the assay of MX in pharmaceutical formulations, plasma and in urine samples. Average recoveries of 99.8 ± 1.1%,
100.2 ± 0.9% and 100.9 ± 1.1% were obtained for MX in tablet, plasma and urine sample respectively. 相似文献
395.
We consider a nonlocal boundary value problem for a viscoelastic equation with a Bessel operator and a weighted integral condition and we prove a general decay result. We also give an example to show that our general result gives the optimal decay rate for ceratin polynomially decaying relaxation functions. This result improves some other results in the literature. 相似文献
396.
Resonant ionization spectroscopy (RIS) and resonant ionization mass spectroscopy (RIMS) are employed to detect the photodissociation product of sodium iodide molecules in a molecular beam in an intense laser field in the absence of the buffer gases. Time of flight mass spectra is recorded. In particular, the appearances of multiphoton ionization are discussed. 相似文献
397.
We consider a second order elliptic equation with known rapidly oscillated coefficient. The equation appears to describe such problems as heat transfer in composite materials, flow in non-homogeneous porous media as well as in many others. For the periodic coefficient the averaging procedure is well known. The non-periodic case is still a challenging problem. We present a two-scale extension approach and apply it on one numerical example in 2D. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献