全文获取类型
收费全文 | 16483篇 |
免费 | 1668篇 |
国内免费 | 1727篇 |
专业分类
化学 | 3797篇 |
晶体学 | 236篇 |
力学 | 1977篇 |
综合类 | 314篇 |
数学 | 10763篇 |
物理学 | 2791篇 |
出版年
2024年 | 32篇 |
2023年 | 147篇 |
2022年 | 174篇 |
2021年 | 272篇 |
2020年 | 435篇 |
2019年 | 386篇 |
2018年 | 359篇 |
2017年 | 453篇 |
2016年 | 492篇 |
2015年 | 377篇 |
2014年 | 646篇 |
2013年 | 1173篇 |
2012年 | 850篇 |
2011年 | 982篇 |
2010年 | 972篇 |
2009年 | 1070篇 |
2008年 | 1121篇 |
2007年 | 1205篇 |
2006年 | 982篇 |
2005年 | 936篇 |
2004年 | 836篇 |
2003年 | 856篇 |
2002年 | 715篇 |
2001年 | 580篇 |
2000年 | 543篇 |
1999年 | 474篇 |
1998年 | 437篇 |
1997年 | 355篇 |
1996年 | 304篇 |
1995年 | 262篇 |
1994年 | 230篇 |
1993年 | 154篇 |
1992年 | 157篇 |
1991年 | 116篇 |
1990年 | 105篇 |
1989年 | 76篇 |
1988年 | 76篇 |
1987年 | 62篇 |
1986年 | 63篇 |
1985年 | 70篇 |
1984年 | 61篇 |
1983年 | 28篇 |
1982年 | 61篇 |
1981年 | 50篇 |
1980年 | 34篇 |
1979年 | 34篇 |
1978年 | 18篇 |
1977年 | 14篇 |
1976年 | 14篇 |
1974年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Shilin Jiang Dr. Yalan Liu Dr. Lin Wang Prof. Zhifang Chai Prof. Wei-Qun Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(60):e202201145
The coordination chemistry of f-block elements (lanthanide and actinide) in molten salts has become a resounding topic in view of its great importance to the research and development (R&D) of molten salt reactors and pyroprocessing. In this Review article, a general overview of the coordination chemistry of f-block elements in molten salts is provided including past achievements and recent advances. Particular emphases are placed on the oxidation state, speciation, and solution structure of f-block metal ions in molten salts, as well as their relationships with the salt composition. Furthermore, this review briefly discusses the spectroscopic and theoretical methods that complement each other in revealing the coordination properties. 相似文献
2.
3.
Tomoyuki Nakatsuka 《Mathematische Nachrichten》2021,294(1):98-117
We study the existence of a time‐periodic solution with pointwise decay properties to the Navier–Stokes equation in the whole space. We show that if the time‐periodic external force is sufficiently small in an appropriate sense, then there exists a time‐periodic solution of the Navier–Stokes equation such that and uniformly in as . Our solution decays faster than the time‐periodic Stokes fundamental solution and the faster decay of its spatial derivatives of higher order is also described. 相似文献
4.
Laurens Kooijman Dr. Matthias Schuster Christian Baumann Simon Jurt Dr. Frank Löhr Dr. Boris Fürtig Prof. Dr. Peter Güntert Prof. Dr. Oliver Zerbe 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(47):21151-21158
To achieve efficient proton pumping in the light-driven proton pump bacteriorhodopsin (bR), the protein must be tightly coupled to the retinal to rapidly convert retinal isomerization into protein structural rearrangements. Methyl group dynamics of bR embedded in lipid nanodiscs were determined in the dark-adapted state, and were found to be mostly well ordered at the cytosolic side. Methyl groups in the M145A mutant of bR, which displays only 10 % residual proton pumping activity, are less well ordered, suggesting a link between side-chain dynamics on the cytosolic side of the bR cavity and proton pumping activity. In addition, slow conformational exchange, attributed to low frequency motions of aromatic rings, was indirectly observed for residues on the extracellular side of the bR cavity. This may be related to reorganization of the water network. These observations provide a detailed picture of previously undescribed equilibrium dynamics on different time scales for ground-state bR. 相似文献
5.
ABSTRACTThe Coupled-Cluster (CC) theory is one of the most successful high precision methods used to solve the stationary Schrödinger equation. In this article, we address the mathematical foundation of this theory with focus on the advances made in the past decade. Rather than solely relying on spectral gap assumptions (non-degeneracy of the ground state), we highlight the importance of coercivity assumptions – Gårding type inequalities – for the local uniqueness of the CC solution. Based on local strong monotonicity, different sufficient conditions for a local unique solution are suggested. One of the criteria assumes the relative smallness of the total cluster amplitudes (after possibly removing the single amplitudes) compared to the Gårding constants. In the extended CC theory the Lagrange multipliers are wave function parameters and, by means of the bivariational principle, we here derive a connection between the exact cluster amplitudes and the Lagrange multipliers. This relation might prove useful when determining the quality of a CC solution. Furthermore, the use of an Aubin–Nitsche duality type method in different CC approaches is discussed and contrasted with the bivariational principle. 相似文献
6.
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
7.
8.
9.
10.
We discuss an error estimation procedure for the global error of collocation schemes applied to solve singular boundary value problems with a singularity of the first kind. This a posteriori estimate of the global error was proposed by Stetter in 1978 and is based on the idea of Defect Correction, originally due to Zadunaisky. Here, we present a new, carefully designed modification of this error estimate which not only results in less computational work but also appears to perform satisfactorily for singular problems. We give a full analytical justification for the asymptotical correctness of the error estimate when it is applied to a general nonlinear regular problem. For the singular case, we are presently only able to provide computational evidence for the full convergence order, the related analysis is still work in progress. This global estimate is the basis for a grid selection routine in which the grid is modified with the aim to equidistribute the global error. This procedure yields meshes suitable for an efficient numerical solution. Most importantly, we observe that the grid is refined in a way reflecting only the behavior of the solution and remains unaffected by the unsmooth direction field close to the singular point. 相似文献