全文获取类型
收费全文 | 14199篇 |
免费 | 567篇 |
国内免费 | 25篇 |
专业分类
化学 | 9853篇 |
晶体学 | 104篇 |
力学 | 374篇 |
综合类 | 1篇 |
数学 | 1876篇 |
物理学 | 2583篇 |
出版年
2023年 | 111篇 |
2022年 | 169篇 |
2021年 | 323篇 |
2020年 | 284篇 |
2019年 | 270篇 |
2018年 | 285篇 |
2017年 | 252篇 |
2016年 | 580篇 |
2015年 | 456篇 |
2014年 | 480篇 |
2013年 | 949篇 |
2012年 | 974篇 |
2011年 | 1049篇 |
2010年 | 638篇 |
2009年 | 586篇 |
2008年 | 943篇 |
2007年 | 911篇 |
2006年 | 742篇 |
2005年 | 669篇 |
2004年 | 528篇 |
2003年 | 504篇 |
2002年 | 427篇 |
2001年 | 303篇 |
2000年 | 271篇 |
1999年 | 189篇 |
1998年 | 152篇 |
1997年 | 124篇 |
1996年 | 156篇 |
1995年 | 117篇 |
1994年 | 108篇 |
1993年 | 131篇 |
1992年 | 115篇 |
1991年 | 80篇 |
1990年 | 66篇 |
1989年 | 53篇 |
1988年 | 51篇 |
1987年 | 44篇 |
1986年 | 43篇 |
1985年 | 90篇 |
1984年 | 84篇 |
1983年 | 54篇 |
1982年 | 53篇 |
1981年 | 46篇 |
1980年 | 51篇 |
1979年 | 25篇 |
1978年 | 43篇 |
1977年 | 26篇 |
1976年 | 28篇 |
1975年 | 31篇 |
1974年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
931.
Elena Fernández Manuel Ortuño Andrés Márquez Rosa Fuentes Inmaculada Pascual 《Optik》2010,121(2):151-158
Holographic data pages were stored in a polyvinyl alcohol (PVA)/acrylamide (AA) photopolymer. This material is formed of AA photopolymers which are considered interesting materials for recording holographic memories. A liquid crystal device was used to modify the object beam and store the data pages in the material. During the storage process, some parameters like exposure time, beam ratio and reading beam intensity were controlled to obtain high image quality after the reconstruction process. The bit error rate (BER) was calculated fitting the histograms of the images to determine what parameters improve the quality of the images. 相似文献
932.
933.
B. R. L. Galvão J. A. Corzo‐Espinoza P. J. S. B. Caridade A. J. C. Varandas 《国际化学动力学杂志》2011,43(7):345-352
Quasiclassical trajectories have been run to study the fundamental one‐quantum vibrational transition formed from collisions of ground‐state nitric oxide with atomic oxygen at temperatures of 500, 750, and 1000 K. Two adiabatic potential energy surfaces of different symmetry (2A′ and 2A″ of NO2) have been utilized. The rate constant for the title process is given along with the rotational distributions, and the results shown to corroborate previous atmospheric models that describe the nascent state by a Maxwell–Boltzmann distribution at the local temperature. © 2011 Wiley Peiodicals, Inc. Int J Chem Kinet 43: 345–352, 2011 相似文献
934.
935.
P. Español J. A. de la Torre M. Ferrario G. Ciccotti 《The European physical journal. Special topics》2011,200(1):107-129
The method of constraints in molecular dynamics is useful because it avoids the resolution of high frequency motions with
very small time steps. However, the price to pay is that both the dynamics and the statistics of a constrained system differ
from those of the unconstrained one. Instead of using constraints, we propose to dispose of high frequency motions by a coarse-graining
procedure in which fast variables are eliminated. These fast variables are thus modeled as friction and thermal fluctuations.
We illustrate the methodology with a simple model case, a diatomic molecule in a monoatomic solvent, in which the bond between
the atoms of a diatomic molecule is stiff. Although the example is very simple and does not display the interesting effects
of “wrong” statistics of the constrained system (i.e. the well-known issue connected to the Fixman potential), it is well
suited to give the proof of concept of the whole procedure. 相似文献
936.
Alexandre Marletta M.L. Vega Y. Galvão Gobato R.M. Faria 《Applied Surface Science》2010,256(10):3018-213
In this work, we have studied the surface morphology of photo-irradiated poly(p-phenylene vinylene) (PPV) thin films by using atomic force microscopy (AFM). We have analyzed the first-order statistical parameters, the height distribution and the distance between selected peaks. The second-order statistical analysis was introduced calculating the auto-covariance function to determine the correlation length between heights. We have observed that the photo-irradiation process produces a surface topology more homogeneous and isotropic such as a normal surface. In addition, the polymer surface irradiation can be used as a new methodology to obtain materials optically modified. 相似文献
937.
938.
In this paper, matrix orthogonal polynomials in the real line are described in terms of a Riemann–Hilbert problem. This approach provides an easy derivation of discrete equations for the corresponding matrix recursion coefficients. The discrete equation is explicitly derived in the matrix Freud case, associated with matrix quartic potentials. It is shown that, when the initial condition and the measure are simultaneously triangularizable, this matrix discrete equation possesses the singularity confinement property, independently if the solution under consideration is given by the recursion coefficients to quartic Freud matrix orthogonal polynomials or not. 相似文献
939.
Leitão Jorge C. Parente Lopes João M. Viana Altmann Eduardo G. 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(10):1-10
The European Physical Journal B - A way to make financial models effective is by letting them to represent the so called “fat tails”, i.e., extreme changes in stock prices that are... 相似文献
940.
Optical characterization of sol gel TiO<Subscript>2</Subscript> monoliths doped with Brilliant Green
S. A. Tomás O. Zelaya R. Palomino R. Lozada O. García J. M. Yáñez A. Ferreira da Silva 《The European physical journal. Special topics》2008,153(1):255-258
Amorphous titanium dioxide monoliths doped with brilliant green (BG) were synthesized by the sol-gel process. The optical
properties of the monoliths were characterized by Photoacoustic Spectroscopy and Photoluminescence Spectroscopy. The absorption
spectra for the BG-doped TiO2 monoliths exhibited two well defined absorption regions: a band below 400 nm corresponding to TiO2 absorption and three absorption bands centered at 424 nm, 588 nm, and 632 nm due to brilliant green. While the undoped TiO2 monoliths showed no luminescence, the doped samples showed a strong luminescence band at 673 nm, which increased its intensity
for increasing organic dye doping. 相似文献