全文获取类型
收费全文 | 816篇 |
免费 | 31篇 |
国内免费 | 2篇 |
专业分类
化学 | 552篇 |
晶体学 | 1篇 |
力学 | 25篇 |
数学 | 131篇 |
物理学 | 140篇 |
出版年
2023年 | 12篇 |
2022年 | 11篇 |
2021年 | 36篇 |
2020年 | 21篇 |
2019年 | 20篇 |
2018年 | 14篇 |
2017年 | 13篇 |
2016年 | 34篇 |
2015年 | 26篇 |
2014年 | 31篇 |
2013年 | 50篇 |
2012年 | 57篇 |
2011年 | 70篇 |
2010年 | 32篇 |
2009年 | 32篇 |
2008年 | 44篇 |
2007年 | 44篇 |
2006年 | 37篇 |
2005年 | 55篇 |
2004年 | 38篇 |
2003年 | 27篇 |
2002年 | 22篇 |
2001年 | 11篇 |
2000年 | 6篇 |
1999年 | 12篇 |
1998年 | 3篇 |
1997年 | 10篇 |
1996年 | 15篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1988年 | 5篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1980年 | 5篇 |
1978年 | 3篇 |
1974年 | 4篇 |
1962年 | 1篇 |
1960年 | 2篇 |
1954年 | 1篇 |
1946年 | 1篇 |
1939年 | 1篇 |
1938年 | 1篇 |
1936年 | 1篇 |
1897年 | 1篇 |
1887年 | 1篇 |
排序方式: 共有849条查询结果,搜索用时 93 毫秒
1.
Riccardo Adami Ugo Boscain Valentina Franceschi Dario Prandi 《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2021,38(4):1095-1113
In this paper we show that, for a sub-Laplacian Δ on a 3-dimensional manifold M, no point interaction centered at a point exists. When M is complete w.r.t. the associated sub-Riemannian structure, this means that Δ acting on is essentially self-adjoint in . A particular example is the standard sub-Laplacian on the Heisenberg group. This is in stark contrast with what happens in a Riemannian manifold N, whose associated Laplace-Beltrami operator acting on is never essentially self-adjoint in , if . We then apply this result to the Schrödinger evolution of a thin molecule, i.e., with a vanishing moment of inertia, rotating around its center of mass. 相似文献
2.
Mathematical Programming - Flows over time have received substantial attention from both an optimization and (more recently) a game-theoretic perspective. In this model, each arc has an associated... 相似文献
3.
Iacus Stefano Maria Santamaria Carlos Sermi Francesco Spyratos Spyros Tarchi Dario Vespe Michele 《Nonlinear dynamics》2020,101(3):1901-1919
Nonlinear Dynamics - Countries in Europe took different mobility containment measures to curb the spread of COVID-19. The European Commission asked mobile network operators to share on a... 相似文献
4.
Dario Tamascelli 《Entropy (Basel, Switzerland)》2020,22(11)
The chain mapping of structured environments is a most powerful tool for the simulation of open quantum system dynamics. Once the environmental bosonic or fermionic degrees of freedom are unitarily rearranged into a one dimensional structure, the full power of Density Matrix Renormalization Group (DMRG) can be exploited. Beside resulting in efficient and numerically exact simulations of open quantum systems dynamics, chain mapping provides an unique perspective on the environment: the interaction between the system and the environment creates perturbations that travel along the one dimensional environment at a finite speed, thus providing a natural notion of light-, or causal-, cone. In this work we investigate the transport of excitations in a chain-mapped bosonic environment. In particular, we explore the relation between the environmental spectral density shape, parameters and temperature, and the dynamics of excitations along the corresponding linear chains of quantum harmonic oscillators. Our analysis unveils fundamental features of the environment evolution, such as localization, percolation and the onset of stationary currents. 相似文献
5.
AbstractRealistic stochastic modeling is increasingly requiring the use of bounded noises. In this work, properties and relationships of commonly employed bounded stochastic processes are investigated within a solid mathematical ground. Four families are object of investigation: the Sine-Wiener (SW), the Doering–Cai–Lin (DCL), the Tsallis–Stariolo–Borland (TSB), and the Kessler–Sørensen (KS) families. We address mathematical questions on existence and uniqueness of the processes defined through Stochastic Differential Equations, which often conceal non-obvious behavior, and we explore the behavior of the solutions near the boundaries of the state space. The expression of the time-dependent probability density of the Sine-Wiener noise is provided in closed form, and a close connection with the Doering–Cai–Lin noise is shown. Further relationships among the different families are explored, pathwise and in distribution. Finally, we illustrate an analogy between the Kessler–Sørensen family and Bessel processes, which allows to relate the respective local times at the boundaries. 相似文献
6.
7.
Dr. Luca Fornasari Dr. Anna Olejniczak Dr. Federica Rossi Dr. Simone d'Agostino Prof. Michele R. Chierotti Prof. Roberto Gobetto Prof. Andrzej Katrusiak Prof. Dario Braga 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(22):5061-5069
The structures and solid-state dynamics of the supramolecular salts of the general formula [(12-crown-4)2 ⋅ DABCOH2](X)2 (where DABCO=1,4-diazabicyclo[2.2.2]octane, X=BF4, ClO4) have been investigated as a function of temperature (from 100 to 360 K) and pressure (up to 3.4 GPa), through the combination of variable-temperature and variable-pressure XRD techniques and variable-temperature solid-state NMR spectroscopy. The two salts are isomorphous and crystallize in the enantiomeric space groups P3221 and P3121. All building blocks composing the supramolecular complex display dynamic processes at ambient temperature and pressure. It has been demonstrated that the motion of the crown ethers is maintained on lowering the temperature (down to 100 K) or on increasing the pressure (up to 1.5 GPa) thanks to the correlation between neighboring molecules, which mesh and rotate in a concerted manner similar to spiral gears. Above 1.55 GPa, a collapse-type transition to a lower-symmetry ordered structure, not attainable at a temperature of 100 K, takes place, proving, thus, that the pressure acts as the means to couple and decouple the gears. The relationship between temperature and pressure effects on molecular motion in the solid state has also been discussed. 相似文献
8.
Nicholas Favalli Gabriele Bassi Tania Zanetti Jrg Scheuermann Dario Neri 《Helvetica chimica acta》2019,102(4)
The construction of DNA‐encoded chemical libraries (DECLs) crucially relies on the availability of chemical reactions, which are DNA‐compatible and which exhibit high conversion rates for a large number of diverse substrates. In this work, we present our optimization and validation procedures for three copper and palladium‐catalyzed reactions (Suzuki cross‐coupling, Sonogashira cross‐coupling, and copper(I)‐catalyzed alkyne‐azide cycloaddition (CuAAC)), which have been successfully used by our group for the construction of large encoded libraries. 相似文献
9.
10.
Ricerche di Matematica - This paper provides an account of results and methods from the theory of infinite groups admitting only finitely many normalizers of subgroups with a given property. Some... 相似文献