全文获取类型
收费全文 | 2789篇 |
免费 | 154篇 |
国内免费 | 13篇 |
专业分类
化学 | 2119篇 |
晶体学 | 10篇 |
力学 | 126篇 |
数学 | 327篇 |
物理学 | 374篇 |
出版年
2023年 | 30篇 |
2022年 | 24篇 |
2021年 | 58篇 |
2020年 | 67篇 |
2019年 | 65篇 |
2018年 | 43篇 |
2017年 | 36篇 |
2016年 | 89篇 |
2015年 | 82篇 |
2014年 | 94篇 |
2013年 | 147篇 |
2012年 | 217篇 |
2011年 | 256篇 |
2010年 | 125篇 |
2009年 | 142篇 |
2008年 | 218篇 |
2007年 | 204篇 |
2006年 | 207篇 |
2005年 | 196篇 |
2004年 | 169篇 |
2003年 | 134篇 |
2002年 | 116篇 |
2001年 | 51篇 |
2000年 | 28篇 |
1999年 | 20篇 |
1998年 | 20篇 |
1997年 | 20篇 |
1996年 | 22篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 8篇 |
1992年 | 14篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有2956条查询结果,搜索用时 15 毫秒
101.
Linear bis dithiocarbamates are conveniently obtained from symmetrical disubstituted α,ω-alkanediamines whose preparation is reported. 相似文献
102.
Importance of the Correlation between Width and Length in the Shape Analysis of Nanorods: Use of a 2D Size Plot To Probe Such a Correlation 下载免费PDF全文
Prof. Clément Roux Dr. Céline Delmas Prof. Jean‐Daniel Marty Dr. Myrtil L. Kahn Dr. Christophe Mingotaud 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(35):12424-12429
Analysis of nanoparticle size through a simple 2D plot is proposed in order to extract the correlation between length and width in a collection or a mixture of anisotropic particles. Compared to the usual statistics on the length associated with a second and independent statistical analysis of the width, this simple plot easily points out the various types of nanoparticles and their (an)isotropy. For each class of nano‐objects, the relationship between width and length (i.e., the strong or weak correlations between these two parameters) may suggest information concerning the nucleation/growth processes. It allows one to follow the effect on the shape and size distribution of physical or chemical processes such as simple ripening. Various electron microscopy pictures from the literature or from the authors′ own syntheses are used as examples to demonstrate the efficiency and simplicity of the proposed 2D plot combined with a multivariate analysis. 相似文献
103.
Christophe Lacave Toan T. Nguyen Benoit Pausader 《Journal of Mathematical Fluid Mechanics》2014,16(2):375-406
We investigate the influence of the topography on the lake equations which describe the two-dimensional horizontal velocity of a three-dimensional incompressible flow. We show that the lake equations are structurally stable under Hausdorff approximations of the fluid domain and L p perturbations of the depth. As a byproduct, we obtain the existence of a weak solution to the lake equations in the case of singular domains and rough bottoms. Our result thus extends earlier works by Bresch and Métivier treating the lake equations with a fixed topography and by Gérard-Varet and Lacave treating the Euler equations in singular domains. 相似文献
104.
105.
Christophe Weibel 《Discrete and Computational Geometry》2012,47(3):519-537
It is known that in the Minkowski sum of r polytopes in dimension d, with r<d, the number of vertices of the sum can be as high as the product of the number of vertices in each summand. However, the
number of vertices for sums of more polytopes was unknown so far. 相似文献
106.
The analysis of changes in the vibrational spectrum of infrared active molecules adsorbed on a ionic surface containing point or extended defects can be an efficient method to determine the nature and density of surface defects. We study the infrared response of ammonia molecules deposited on a ionic surface of MgO containing charge vacancies and dipolar defects in various concentrations and distributions and show significant changes assigned to the defects signature. A Monte Carlo approach is used to randomly deposit the probe molecules on the surface displaying random or regularly arranged defects at low temperature. 相似文献
107.
108.
109.
110.
Adrián Schwarzenberg Farid Ichou Richard B. Cole Xavier Machuron‐Mandard Christophe Junot Denis Lesage Jean‐Claude Tabet 《Journal of mass spectrometry : JMS》2013,48(5):576-586
Organophosphorus compounds have played important roles as pesticides, chemical warfare agents and extractors of radioactive material. Structural elucidation of phosphonates poses a particular challenge because their initial forms can be hydrolyzed, thus, degradation products may predominate in samples acquired in the field. The analysis of non‐volatile organophosphorus compounds and their degradation products is possible using electrospray tandem mass spectrometry ESI‐MS/MS. Here, we present a generic strategy that allows the unambiguous identification of substituents for two families of organophosphorus compounds: the phosphonates and phosphates. General fragmentation rules were deduced based on the study of decomposition pathways of 55 organophosphorus esters, including examples found in the literature. Multistage MS (MSn) experiments at high resolution in a hybrid mass spectrometer provide accurate mass measurements, whereas collision‐induced dissociation experiments in a triple quadrupole give access to small fragment ions. The creation of a specific nomenclature for each possible structure of organophosphorus compound, depending on the alkyl side chain linked to the oxygen, was achieved by applying these fragmentation rules. This led to the creation of an ‘identification tree’ based upon the unique consecutive decomposition pathways uncovered for each individual compound. Hence, seven structural motifs were created that orient an unequivocal identification using the ‘identification tree’. Despite the similar structures of the ensemble of phosphate and phosphonate esters, distinct identifications based upon characteristic neutral losses and diagnostic fragment ions were possible in all cases. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献