全文获取类型
收费全文 | 1161篇 |
免费 | 53篇 |
国内免费 | 6篇 |
专业分类
化学 | 759篇 |
晶体学 | 7篇 |
力学 | 32篇 |
数学 | 190篇 |
物理学 | 232篇 |
出版年
2023年 | 9篇 |
2022年 | 20篇 |
2021年 | 26篇 |
2020年 | 33篇 |
2019年 | 36篇 |
2018年 | 25篇 |
2017年 | 14篇 |
2016年 | 37篇 |
2015年 | 46篇 |
2014年 | 45篇 |
2013年 | 65篇 |
2012年 | 94篇 |
2011年 | 111篇 |
2010年 | 57篇 |
2009年 | 51篇 |
2008年 | 88篇 |
2007年 | 72篇 |
2006年 | 57篇 |
2005年 | 48篇 |
2004年 | 40篇 |
2003年 | 28篇 |
2002年 | 22篇 |
2001年 | 10篇 |
2000年 | 13篇 |
1999年 | 7篇 |
1998年 | 12篇 |
1997年 | 6篇 |
1995年 | 8篇 |
1994年 | 5篇 |
1993年 | 9篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 9篇 |
1984年 | 12篇 |
1983年 | 3篇 |
1981年 | 5篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1971年 | 4篇 |
1969年 | 5篇 |
排序方式: 共有1220条查询结果,搜索用时 15 毫秒
41.
Xinghui Qi Dr. Sébastien Pillet Dr. Coen de Graaf Michał Magott Dr. El-Eulmi Bendeif Dr. Philippe Guionneau Dr. Mathieu Rouzières Dr. Valérie Marvaud Dr. Olaf Stefańczyk Dr. Dawid Pinkowicz Dr. Corine Mathonière 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(8):3141-3145
The photoinduced properties of the octacoordinated complex K4MoIV(CN)8⋅2 H2O were studied by theoretical calculations, crystallography, and optical and magnetic measurements. The crystal structure recorded at 10 K after blue light irradiation reveals an heptacoordinated Mo(CN)7 species originating from the light-induced cleavage of one Mo−CN bond, concomitant with the photoinduced formation of a paramagnetic signal. When this complex is heated to 70 K, it returns to its original diamagnetic ground state, demonstrating full reversibility. The photomagnetic properties show a partial conversion into a triplet state possessing significant magnetic anisotropy, which is in agreement with theoretical studies. Inspired by these results, we isolated the new compound [K(crypt-222)]3[MoIV(CN)7]⋅3 CH3CN using a photochemical pathway, confirming that photodissociation leads to a stable heptacyanomolybdate(IV) species in solution. 相似文献
42.
Dr. Victor de Seauve Dr. Marie-Angélique Languille Dr. Mathieu Kociak Dr. Stéphanie Belin Dr. James Ablett Prof. Christine Andraud Prof. Odile Stéphan Dr. Jean-Pascal Rueff Dr. Emiliano Fonda Prof. Bertrand Lavédrine 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(23):9198-9204
The first colour photographs were created by a process introduced by Edmond Becquerel in 1848. The nature of these photochromatic images colours motivated a debate between scientists during the XIXth century, which is still not settled. We present the results of chemical analysis (EDX, HAXPES and EXAFS) and morphology studies (SEM, STEM) aiming at explaining the optical properties of the photochromatic images (UV-visible spectroscopy and low loss EELS). We rule out the two hypotheses (pigment and interferences) that have prevailed since 1848, respectively based on variations in the oxidation degree of the compound forming the sensitized layer and periodically spaced photolytic silver planes. A study of the silver nanoparticles dispersions contained in the coloured layers showed specific localizations and sizes distributions of the nanoparticles for each colour. These results allow us to formulate a plasmonic hypothesis on the origin of the photochromatic images colours. 相似文献
43.
Wenbin Guo Dr. Nathalie Daro Dr. Sébastien Pillet Dr. Mathieu Marchivie Dr. El-Eulmi Bendeif Dr. Elodie Tailleur Dr. Kittipong Chainok Dominique Denux Dr. Guillaume Chastanet Prof. Philippe Guionneau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(57):12927-12930
The current craze for research around the spin crossover phenomenon can be justified to some extent by the mechanical properties due to the decrease of volume associated with the transition of the metal ion from the HS state to the LS state. As demonstrated here, the molecular complex [Fe(PM-pBrA)2(NCS)2] exhibits, on the contrary, an increase of the unit-cell volume from HS to LS. This counter-intuitive and unprecedented behavior that concerns both the thermal and the photoexcited spin conversions is revealed by a combination of single-crystal and powder X-ray diffraction complemented by magnetic measurements. Interestingly, this abnormal volume change appears concomitant with the wide rotation of a phenyl ring which induces a drastic modification, though reversible, of the structural packing within the crystal. In addition, the light-induced HS state obtained through the Light-Induced Excited Spin-State Trapping shows a remarkably high relaxation temperature, namely T(LIESST), of 109 K, one of the highest so far reported. The above set of quite unusual characteristics opens up new fields of possibilities within the development of spin crossover materials. 相似文献
44.
45.
Joe Warren Scott Schaefer Anil N. Hirani Mathieu Desbrun 《Advances in Computational Mathematics》2007,27(3):319-338
In this paper we provide an extension of barycentric coordinates from simplices to arbitrary convex sets. Barycentric coordinates
over convex 2D polygons have found numerous applications in various fields as they allow smooth interpolation of data located
on vertices. However, no explicit formulation valid for arbitrary convex polytopes has been proposed to extend this interpolation
in higher dimensions. Moreover, there has been no attempt to extend these functions into the continuous domain, where barycentric
coordinates are related to Green’s functions and construct functions that satisfy a boundary value problem. First, we review
the properties and construction of barycentric coordinates in the discrete domain for convex polytopes. Next, we show how
these concepts extend into the continuous domain to yield barycentric coordinates for continuous functions. We then provide
a proof that our functions satisfy all the desirable properties of barycentric coordinates in arbitrary dimensions. Finally,
we provide an example of constructing such barycentric functions over regions bounded by parametric curves and show how they
can be used to perform freeform deformations.
相似文献
46.
Mathieu Van Vyve 《Mathematical Programming》2006,108(1):53-77
Recently, several authors [8, 10] have argued for the use of extended formulations to tighten production planning models.
In this work we present two linear-programming extended formulations of the constant-capacity lot-sizing problem with backlogging.
The first one applies to the problem with a general cost function and has O(n3) variables and constraints. This improves on the more straightforward O(n4) Florian and Klein [2] type formulation. The second one applies when the costs satisfy the Wagner-Whitin property but it
has O(n2) variables and O(n3) constraints. As a by-product, we positively answer an open question of Miller and Wolsey [4] about the tightness of an extended
formulation for the continuous mixing set.
This text presents research results of the Belgian Program on Interuniversity Poles of Attraction initiated by the Belgian
State, Prime Minister's Office, Science Policy Programming. The research was carried out with financial support of the Growth
Project G1RD-1999-00034 (LISCOS) of the European Community. The scientific responsibility is assumed by the author. 相似文献
47.
Mathieu Lobet Masaki Kando James K. Koga Timur Zh. Esirkepov Tatsufumi Nakamura Alexander S. Pirozhkov Sergei V. Bulanov 《Physics letters. A》2013
A method for the controlled generation of intense high frequency electromagnetic fields by a breaking Langmuir wave (relativistic flying mirrors) in a gradually inhomogeneous plasma is proposed. The wave breaking threshold depends on the local plasma density gradient. Compression, chirping and frequency multiplication of an electromagnetic wave reflected from relativistic mirrors is demonstrated using Particle-In-Cell simulations. Adjusting the shape of the density profile enables control of the reflected light properties. 相似文献
48.
49.
Optical sectioning in wide-field microscopy is achieved by illumination of the object with a continuously moving single-spatial-frequency pattern and detecting the image with a smart pixel detector array. This detector performs an on-chip electronic signal processing that extracts the optically sectioned image. The optically sectioned image is directly observed in real time without any additional postprocessing. 相似文献
50.
Philippe Gravejat Mathieu Lewin éric Séré 《Communications in Mathematical Physics》2009,286(1):179-215
We study the reduced Bogoliubov-Dirac-Fock (BDF) energy which allows to describe relativistic electrons interacting with the
Dirac sea, in an external electrostatic potential. The model can be seen as a mean-field approximation of Quantum Electrodynamics
(QED) where photons and the so-called exchange term are neglected. A state of the system is described by its one-body density
matrix, an infinite rank self-adjoint operator which is a compact perturbation of the negative spectral projector of the free
Dirac operator (the Dirac sea). We study the minimization of the reduced BDF energy under a charge constraint. We prove the
existence of minimizers for a large range of values of the charge, and any positive value of the coupling constant α. Our
result covers neutral and positively charged molecules, provided that the positive charge is not large enough to create electron-positron
pairs. We also prove that the density of any minimizer is an L
1 function and compute the effective charge of the system, recovering the usual renormalization of charge: the physical coupling
constant is related to α by the formula αphys ≃ α(1 + 2α/(3π) log Λ)−1, where Λ is the ultraviolet cut-off. We eventually prove an estimate on the highest number of electrons which can be bound
by a nucleus of charge Z. In the nonrelativistic limit, we obtain that this number is ≤ 2Z, recovering a result of Lieb. This work is based on a series of papers by Hainzl, Lewin, Séré and Solovej on the mean-field
approximation of no-photon QED. 相似文献