全文获取类型
收费全文 | 3472篇 |
免费 | 102篇 |
国内免费 | 16篇 |
专业分类
化学 | 2108篇 |
晶体学 | 29篇 |
力学 | 65篇 |
数学 | 463篇 |
物理学 | 925篇 |
出版年
2022年 | 40篇 |
2021年 | 38篇 |
2020年 | 39篇 |
2019年 | 44篇 |
2018年 | 38篇 |
2017年 | 29篇 |
2016年 | 75篇 |
2015年 | 81篇 |
2014年 | 84篇 |
2013年 | 162篇 |
2012年 | 141篇 |
2011年 | 170篇 |
2010年 | 98篇 |
2009年 | 108篇 |
2008年 | 156篇 |
2007年 | 130篇 |
2006年 | 132篇 |
2005年 | 150篇 |
2004年 | 98篇 |
2003年 | 96篇 |
2002年 | 100篇 |
2001年 | 66篇 |
2000年 | 58篇 |
1999年 | 44篇 |
1998年 | 31篇 |
1997年 | 43篇 |
1996年 | 50篇 |
1995年 | 53篇 |
1994年 | 59篇 |
1993年 | 70篇 |
1992年 | 64篇 |
1991年 | 43篇 |
1990年 | 44篇 |
1989年 | 42篇 |
1988年 | 36篇 |
1987年 | 43篇 |
1986年 | 44篇 |
1985年 | 43篇 |
1984年 | 46篇 |
1983年 | 33篇 |
1982年 | 37篇 |
1981年 | 44篇 |
1980年 | 46篇 |
1979年 | 37篇 |
1978年 | 36篇 |
1977年 | 40篇 |
1976年 | 40篇 |
1974年 | 24篇 |
1973年 | 36篇 |
1970年 | 21篇 |
排序方式: 共有3590条查询结果,搜索用时 125 毫秒
1.
2.
de Santana Felipe Silva Gracioso Louise Hase Karolski Bruno dos Passos Galluzzi Baltazar Marcela Mendes Maria Anita do Nascimento Claudio Augusto Oller Perpetuo Elen Aquino 《Applied biochemistry and biotechnology》2019,189(1):103-115
Applied Biochemistry and Biotechnology - The human exposure to bisphenol A (BPA) occurs frequently. Once, this compound was one of the highest volume chemicals produced worldwide and used as a... 相似文献
3.
A synthesis of methyl 2-oxo-5-vinyl-tetrahydrofuran-3-carboxylate involving five synthetic steps from commercially available 3,4-dihydroxybutene is reported. 相似文献
4.
Felix Klein 《Mathematische Annalen》1870,2(2):198-226
Ohne Zusammenfassung 相似文献
5.
F. Klein 《Mathematische Annalen》1883,22(2):246-248
Ohne ZusammenfassungAus den Sitzungsberichten der physikalisch-medicinischen Societät zu Erlangen vom 10. November 1873Es ist dies diejenige Arbeit, auf welche Hr. Wedekind bei seiner Definition des complexen Doppelverhältnisses von vier Punkten der Kugel Bezug nimmt, Bd. 9 dieser Annalen, pag. 209 ff. [Febr. 1883]. 相似文献
6.
F. Klein 《Fresenius' Journal of Analytical Chemistry》1885,24(1):379-388
Ohne ZusammenfassungNieder-Ingelheim, 3. Mai 1885. 相似文献
7.
A time discrete scheme is used to approximate the solution toa phase field system of PenroseFife type with a non-conservedorder parameter. An a posteriori error estimate is presentedthat allows the estimation of the difference between continuousand semidiscrete solutions by quantities that can be calculatedfrom the approximation and given data. 相似文献
8.
Many biological and medical studies have as a response of interest the time to occurrence of some event, such as the occurrence of a particular symptom or disease, remission, relapse, death due to some specific disease, or simply death. In this paper we study the problem of assessing the effect of potential risk factors on the outcome event of interest through a parametric or semi-parametric frailty model where the lifetimes have a reason to be considered dependent. This dependence may arise because of multiple endpoints within the same individual or because, when studying a single endpoint, there are natural groupings between study subjects. The objective of this paper is to extend both parametric and semi-parametric approaches to regression analysis in which the lifetimes of individuals in a group are effected by the same random frailty which follows a positive stable distribution. Some comparisons of the properties of this frailty distribution with other frailty distributions are made and an example which assesses the effect of a treatment in a litter-matched tumorigenesis study is presented. 相似文献
9.
Europium (Eu+) ions were confined in a Paul trap and detected by non-destructive method. Storage time of Eu+ ions achieved in vacuum was improved by orders of magnitude employing buffer gas cooling. The experimentally detected signal
was fitted to the ion response signal and the total number of ions trapped was estimated. It is found that the peak signal
amplitude as well as the product of FWHM and the peak signal amplitude is proportional to the total number of trapped ions.
The trapped ion secular frequency was swept at different rates and its effect on the absorption line profile was studied both
experimentally and theoretically. 相似文献
10.
In recent years there has been considerable progress in the application of large-eddy simulation (LES) to increasingly complex flow configurations. Nevertheless a lot of fundamental problems still need to be solved in order to apply LES in a reliable way to real engineering problems, where typically finite-volume codes on unstructured meshes are used. A self-adaptive discretisation scheme, in the context of an unstructured finite-volume flow solver, is investigated in the case of isotropic turbulence at infinite Reynolds number. The Smagorinsky and dynamic Smagorinsky sub-grid scale models are considered. A discrete interpolation filter is used for the dynamic model. It is one of the first applications of a filter based on the approach presented by Marsden et al. In this work, an original procedure to impose the filter shape through a specific selection process of the basic filters is also proposed. Satisfactory results are obtained using the self-adaptive scheme for implicit LES. When the scheme is coupled with the sub-grid scale models, the numerical dissipation is shown to be dominant over the sub-grid scale component. Nevertheless the effect of the sub-grid scale models appears to be important and beneficial, improving in particular the energy spectra. A test on fully developed channel flow at Reτ = 395 is also performed, comparing the non-limited scheme with the self-adaptive scheme for implicit LES. Once again the introduction of the limiter proves to be beneficial. 相似文献