全文获取类型
收费全文 | 134篇 |
免费 | 3篇 |
国内免费 | 1篇 |
专业分类
化学 | 70篇 |
晶体学 | 3篇 |
力学 | 3篇 |
数学 | 32篇 |
物理学 | 30篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 4篇 |
2014年 | 2篇 |
2013年 | 8篇 |
2012年 | 6篇 |
2011年 | 11篇 |
2010年 | 3篇 |
2009年 | 5篇 |
2008年 | 10篇 |
2007年 | 6篇 |
2006年 | 11篇 |
2005年 | 9篇 |
2004年 | 3篇 |
2003年 | 4篇 |
2002年 | 6篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1976年 | 3篇 |
1963年 | 1篇 |
排序方式: 共有138条查询结果,搜索用时 15 毫秒
41.
Y. Kudriatsev A. Villegas S. Gallardo G. Ramirez R. Asomoza V. Mishurnuy 《Applied Surface Science》2008,254(16):4961-4964
We investigated the work function (WF) change of a silicon surface being under cesium ion bombardment and simultaneous oxygen flooding with various oxygen pressures at the sample surface. It was found that WF of Cs+ ion sputtered Si decreases under oxygen flooding. This decrease provides an essential grow of secondary ion yields of some negative ions, sputtered from Si. At the same time Si− ion yield decreases approximately in two times. In the paper we have discussed possible explanations of our experimental data: we considered a surface composition change, formation of surface dipoles and work function change caused by oxygen adsorption, and their relationships between each other. 相似文献
42.
Jos A. Villegas Nairiti J. Sinha Naozumi Teramoto Christopher D. Von Bargen Darrin J. Pochan Jeffery G. Saven 《Molecules (Basel, Switzerland)》2022,27(4)
Protein complexes perform a diversity of functions in natural biological systems. While computational protein design has enabled the development of symmetric protein complexes with spherical shapes and hollow interiors, the individual subunits often comprise large proteins. Peptides have also been applied to self-assembly, and it is of interest to explore such short sequences as building blocks of large, designed complexes. Coiled-coil peptides are promising subunits as they have a symmetric structure that can undergo further assembly. Here, an α-helical 29-residue peptide that forms a tetrameric coiled coil was computationally designed to assemble into a spherical cage that is approximately 9 nm in diameter and presents an interior cavity. The assembly comprises 48 copies of the designed peptide sequence. The design strategy allowed breaking the side chain conformational symmetry within the peptide dimer that formed the building block (asymmetric unit) of the cage. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) techniques showed that one of the seven designed peptide candidates assembled into individual nanocages of the size and shape. The stability of assembled nanocages was found to be sensitive to the assembly pathway and final solution conditions (pH and ionic strength). The nanocages templated the growth of size-specific Au nanoparticles. The computational design serves to illustrate the possibility of designing target assemblies with pre-determined specific dimensions using short, modular coiled-coil forming peptide sequences. 相似文献
43.
44.
Henry Power Peder A. Tyvand Miguel Villegas 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1991,42(2):198-212
It is well known that a uniform flow past a non-permeable rigid body does not exert a total force upon the surface of the body, however this is not the case when the body is permeable. Power et. al. (1984, 1986) first solved the problem of uniform potential flow past a two-dimensional permeable circular cylinder, with constant permeability, and found that the exterior flow exerts a drag force upon the surface of the cylinder independent of its size and secondly the problem when the uniform potential flow past a porous sphere, with constant permeability, in this case the exterior flow exerts a drag force on the sphere which is linearly dependent on the radius of the sphere. Here we will present the solution of two problems, a uniform potential flow past a porous circular cylinder and past a porous sphere, for each case the porous body is composed of two materials with different permeabilities. In both cases the total force exerted by the exterior flow upon the body is dependent on the thickness of the porous materials, and in the limit when the two permeabilities are equal, the previous results, circular cylinder and sphere, with constant permeability, are recovered. Atlhough, the mathematics involved in the solution of the present problem is simple, due to the nice boundary geometry of the bodies, the final expression for the total force found in each case is quite interesting on the way it depends on the permeability relation, in particular, in the limiting cases of a porous body with solid or hollow core. 相似文献
45.
Crassous A Bernard R Fusil S Bouzehouane K Le Bourdais D Enouz-Vedrenne S Briatico J Bibes M Barthélémy A Villegas JE 《Physical review letters》2011,107(24):247002
Using heterostructures that combine a large-polarization ferroelectric (BiFeO3) and a high-temperature superconductor (YBa2Cu3O(7-δ)), we demonstrate the modulation of the superconducting condensate at the nanoscale via ferroelectric field effects. Through this mechanism, a nanoscale pattern of normal regions that mimics the ferroelectric domain structure can be created in the superconductor. This yields an energy landscape for magnetic flux quanta and, in turn, couples the local ferroelectric polarization to the local magnetic induction. We show that this form of magnetoelectric coupling, together with the possibility to reversibly design the ferroelectric domain structure, allows the electrostatic manipulation of magnetic flux quanta. 相似文献
46.
N. Carmona E. Herrero-Hernandez J. Llopis M. A. Villegas 《Journal of Sol-Gel Science and Technology》2008,47(1):31-37
Anhydrous cobalt(II) chloride has been encapsulated in several inorganic sol–gel matrices with different solvent/water ratios.
Sols were cast into cuvettes and hermetically closed. Such sol–gel materials were found to be sensitive to temperature in the 10–50 °C range showing a
change of colour. General characterisation of the sensitive materials was made by immersion into a thermostatic water bath
and recording of the corresponding visible spectra. The optical response consisted of a change in colour from light pink to
deep blue as the temperature increases. These temperature detectors behave as sensors showing good optical sensitivity in
the range mentioned above and reversibility for more than 30 cycles. The sensors response time is at about 15 min and their
lifetime is 2 months at least. These sol–gel materials have been designed to be applied for preservation and conservation
purposes. High temperatures and cyclical temperature changes can yield severe consequences for the correct preservation of
cultural heritage materials (textiles, archaeological ceramics and other remains, metallic objects and statues, stained glass
windows, etc.) both in museums and outdoors. 相似文献
47.
Ariel Pacetti Fernando Rodriguez Villegas with an appendix by B. Gross. 《Mathematics of Computation》2005,74(251):1545-1557
For a prime we describe an algorithm for computing the Brandt matrices giving the action of the Hecke operators on the space of modular forms of weight and level . For we define a special Hecke stable subspace of which contains the space of modular forms with CM by the ring of integers of and we describe the calculation of the corresponding Brandt matrices.
48.
O. Curcuruto P. Traldi C. Cativiela M. D. Diaz De Villegas J. I. Garcia J. A. Mayoral D. Aj 《Journal of heterocyclic chemistry》1990,27(5):1495-1499
The mass spectrometric behaviour of four isomeric oxazolones is rationalized by means of metastable ion studies and bond order calculations via semiempirical methods. The data allow the identification of a possible intermediate structure of molecular species that accounts easily for the observed primary decomposition pathways. 相似文献
49.
In this paper an asymptotic theory is developed for a new time series model which was introduced in a previous paper [5]. An algorithm for computing estimates of the parameters of this time series model is given, and it is shown that these estimators are asymptotically efficient in the sense that they have the same asymptotic distribution as the maximum likelihood estimators. 相似文献
50.
C. Villegas 《Stochastic Processes and their Applications》1976,4(2):121-133
In 1957, Parzen proved a central limit theorem for a class of scalar processes which he called multilinear processes. In the present paper only stationary bilinear processes are considered, but the theory is generalized to the multivariate case. 相似文献