全文获取类型
收费全文 | 4455篇 |
免费 | 219篇 |
国内免费 | 21篇 |
专业分类
化学 | 2841篇 |
晶体学 | 27篇 |
力学 | 113篇 |
数学 | 808篇 |
物理学 | 906篇 |
出版年
2023年 | 35篇 |
2022年 | 44篇 |
2021年 | 69篇 |
2020年 | 84篇 |
2019年 | 87篇 |
2018年 | 76篇 |
2017年 | 79篇 |
2016年 | 187篇 |
2015年 | 153篇 |
2014年 | 145篇 |
2013年 | 291篇 |
2012年 | 310篇 |
2011年 | 324篇 |
2010年 | 182篇 |
2009年 | 141篇 |
2008年 | 272篇 |
2007年 | 250篇 |
2006年 | 206篇 |
2005年 | 224篇 |
2004年 | 176篇 |
2003年 | 158篇 |
2002年 | 157篇 |
2001年 | 56篇 |
2000年 | 47篇 |
1999年 | 47篇 |
1998年 | 51篇 |
1997年 | 35篇 |
1996年 | 53篇 |
1995年 | 22篇 |
1994年 | 38篇 |
1993年 | 45篇 |
1992年 | 35篇 |
1991年 | 30篇 |
1990年 | 30篇 |
1989年 | 24篇 |
1988年 | 24篇 |
1987年 | 27篇 |
1986年 | 31篇 |
1985年 | 45篇 |
1984年 | 36篇 |
1983年 | 25篇 |
1982年 | 27篇 |
1981年 | 30篇 |
1980年 | 21篇 |
1979年 | 33篇 |
1978年 | 27篇 |
1977年 | 27篇 |
1975年 | 15篇 |
1974年 | 27篇 |
1973年 | 28篇 |
排序方式: 共有4695条查询结果,搜索用时 0 毫秒
1.
Spyridon Koutsoukos Frederik Philippi Francisco Malaret Tom Welton 《Chemical science》2021,12(20):6820
There are thousands of papers published every year investigating the properties and possible applications of ionic liquids. Industrial use of these exceptional fluids requires adequate understanding of their physical properties, in order to create the ionic liquid that will optimally suit the application. Computational property prediction arose from the urgent need to minimise the time and cost that would be required to experimentally test different combinations of ions. This review discusses the use of machine learning algorithms as property prediction tools for ionic liquids (either as standalone methods or in conjunction with molecular dynamics simulations), presents common problems of training datasets and proposes ways that could lead to more accurate and efficient models.In this review article, the authors discuss the use of machine learning algorithms as tools for the prediction of physical and chemical properties of ionic liquids. 相似文献
2.
Nováková Kateřina Hrdlička Vojtěch Navrátil Tomáš Vyskočil Vlastimil Barek Jiří 《Monatshefte für Chemie / Chemical Monthly》2015,146(5):761-769
Monatshefte für Chemie - Chemical Monthly - The voltammetric behavior of 5-nitroindazole was investigated at polished (p-AgSAE) and at mercury meniscus-modified (m-AgSAE) silver solid amalgam... 相似文献
3.
4.
James K. Freericks Elliott H. Lieb Daniel Ueltschi 《Communications in Mathematical Physics》2002,227(2):243-279
The Falicov–Kimball model is a simple quantum lattice model that describes light and heavy electrons interacting with an
on-site repulsion; alternatively, it is a model of itinerant electrons and fixed nuclei. It can be seen as a simplification
of the Hubbard model; by neglecting the kinetic (hopping) energy of the spin up particles, one gets the Falicov–Kimball model.
We show that away from half-filling, i.e. if the sum of the densities of both kinds of particles differs from 1, the particles
segregate at zero temperature and for large enough repulsion. In the language of the Hubbard model, this means creating two
regions with a positive and a negative magnetization.
Our key mathematical results are lower and upper bounds for the sum of the lowest eigenvalues of the discrete Laplace operator
in an arbitrary domain, with Dirichlet boundary conditions. The lower bound consists of a bulk term, independent of the shape
of the domain, and of a term proportional to the boundary. Therefore, one lowers the kinetic energy of the itinerant particles
by choosing a domain with a small boundary. For the Falicov- Kimball model, this corresponds to having a single “compact”
domain that has no heavy particles.
Received: 21 June 2001 / Accepted: 4 January 2002 相似文献
5.
6.
Fully and partially observed stochastic control of systems with nonlinear dynamics and terminal and running costs are considered.
Measure changes are introduced which allow both state and observation dynamics to be thought of as linear. In the case when
the terms of the cost have a special form the measure change transformation “cancels out” the nonlinearities and changes the
original nonlinear problem into a classical LQG one and standard results can be applied. We also consider unnormalized conditional
densities of the whole path as state variables and obtain dynamic programming and verification results.
R. J. Elliott wishes to acknowledge support of the Natural Sciences and Engineering Research Council of Canada, Grant A7964. 相似文献
7.
On‐line coupling of LC and ICP‐MS has been used for fractionation and detection of species of Cu, Fe, I, Se and Zn in human serum. It has been shown that anion exchange chromatography provided better separation capability (both intra‐ and inter‐element) than size‐exclusion chromatography. The mobile phases for ion exchange chromatography consisted of Tris–HNO3 buffer and ammonium salt (nitrate, acetate or formate). Formate was found to be the best mobile phase counter ion, enabling good chromatographic separation, and is acceptable for mass spectrometry too. The quantitative evaluation of element concentrations adhering to individual fractions was performed by the peak area normalization method. The repeatability of results ranged from 3 to 15% (depending on the element concentration level) and represented the main part of the result uncertainty. The accuracy of Cu and Zn fraction determinations was confirmed by comparison with the isotope dilution technique. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
8.
9.
Tomás Chacón Rebollo Antonio Domı́nguez Delgado Enrique D. Fernández Nieto 《Comptes Rendus Mathematique》2004,338(1):85-90
In this work we introduce a class of balanced numerical schemes, up to second order, for the solution of general non-homogeneous hyperbolic systems of conservation laws. We give a general technique to build such schemes. We also prove that they balance up to second order a large class of steady solutions in the whole domain but some subset whose measure tends to zero as the grid size decreases to zero. We finally present an application to Shallow Water equations that exhibit the good performances of some of the schemes introduced. To cite this article: T. Chacón Rebollo et al., C. R. Acad. Sci. Paris, Ser. I 338 (2004). 相似文献
10.