全文获取类型
收费全文 | 20497篇 |
免费 | 738篇 |
国内免费 | 79篇 |
专业分类
化学 | 16526篇 |
晶体学 | 121篇 |
力学 | 310篇 |
数学 | 2526篇 |
物理学 | 1831篇 |
出版年
2024年 | 22篇 |
2023年 | 194篇 |
2022年 | 822篇 |
2021年 | 890篇 |
2020年 | 505篇 |
2019年 | 554篇 |
2018年 | 440篇 |
2017年 | 364篇 |
2016年 | 731篇 |
2015年 | 654篇 |
2014年 | 712篇 |
2013年 | 1283篇 |
2012年 | 1357篇 |
2011年 | 1502篇 |
2010年 | 938篇 |
2009年 | 850篇 |
2008年 | 1256篇 |
2007年 | 1212篇 |
2006年 | 1057篇 |
2005年 | 916篇 |
2004年 | 769篇 |
2003年 | 618篇 |
2002年 | 595篇 |
2001年 | 258篇 |
2000年 | 196篇 |
1999年 | 151篇 |
1998年 | 161篇 |
1997年 | 139篇 |
1996年 | 175篇 |
1995年 | 123篇 |
1994年 | 114篇 |
1993年 | 111篇 |
1992年 | 90篇 |
1991年 | 105篇 |
1990年 | 79篇 |
1989年 | 101篇 |
1988年 | 80篇 |
1987年 | 69篇 |
1986年 | 74篇 |
1985年 | 103篇 |
1984年 | 101篇 |
1983年 | 57篇 |
1982年 | 90篇 |
1981年 | 76篇 |
1980年 | 74篇 |
1979年 | 58篇 |
1978年 | 59篇 |
1977年 | 46篇 |
1976年 | 40篇 |
1975年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
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
24.
Driven and non-equilibrium quantum states of matter have attracted growing interest in both theoretical and experimental studies in condensed matter physics. Recent progress in realizing transient collective states in driven or pumped Dirac materials (DMs) is reviewed herein. In particular, the focus is on optically pumped DMs which are a promising platform for transient excitonic instabilities. Optical pumping combined with the linear (Dirac) dispersion of the electronic spectrum offers a knob for tuning the effective interaction between the photoexcited electrons and holes, and thus provides a way of reducing the critical coupling for excitonic instability. As a result, a transient excitonic condensate could be achieved in a pumped DM while it is not feasible in equilibrium. A unifying theoretical framework is provided for describing transient collective states in 2D and 3D DMs. The experimental signatures are described and numerical estimates of the size of the dynamically induced excitonic gaps and the values of the critical temperatures for several specific systems, are summarized. In addition, general guidelines for identifying promising material candidates are discussed. Finally, comments are provided regarding recent experimental efforts in realizing transient excitonic condensate in pumped DMs, and outstanding issues and possible future directions are outlined. 相似文献
25.
Summary Carbon deposits on the surface ofRu/Fe2O3 catalysts used in the water-gas shift reaction have been investigated by Auger Electron Spectrometry. A correlation has been
found between the thickness of the carbon deposit and the catalytic activity in WGSR. The carbon deposit covers the metallic
active centers and blocks their contact with reagents. The dotting of the iron oxide support with sodium has been found to
reduce the amount of carbon deposit. . 相似文献
26.
27.
28.
The versatile behavior of a trihydrazidophosphoradamantane allowing the synthesis of a variety of neutral, mono- or di-cationic water-soluble molecules of potential interest for biphasic catalysis is reported. 相似文献
29.
This paper attempts to develop a theory of sufficiency in the setting of non-commutative algebras parallel to the ideas in
classical mathematical statistics. Sufficiency of a coarse-graining means that all information is extracted about the mutual
relation of a given family of states. In the paper sufficient coarse-grainings are characterized in several equivalent ways
and the non-commutative analogue of the factorization theorem is obtained. As an application we discuss exponential families.
Our factorization theorem also implies two further important results, previously known only in finite Hilbert space dimension,
but proved here in generality: the Koashi-Imoto theorem on maps leaving a family of states invariant, and the characterization
of the general form of states in the equality case of strong subadditivity.
Supported by the EU Research Training Network Quantum Probability with Applications to Physics, Information Theory and Biology
and Center of Excellence SAS Physics of Information I/2/2005.
Supported by the Hungarian grant OTKA T032662 相似文献
30.
Maria Kordaki Athanasia Balomenou 《International Journal of Computers for Mathematical Learning》2006,11(1):99-135
This study focuses on the constructions in terms of area and perimeter in equivalent triangles developed by students aged 12–15 years-old, using the tools provided by Cabri-Geometry II [Labore (1990). Cabri-Geometry (software), Université de Grenoble]. Twenty-five students participated in a learning experiment where they were asked to construct: (a) pairs of equivalent triangles “in as many ways as possible” and to study their area and their perimeter using any of the tools provided and (b) “any possible sequence of modifications of an original triangle into other equivalent ones”. As regards the concept of area and in contrast to a paper and pencil environment, Cabri provided students with different and potential opportunities in terms of: (a) means of construction, (b) control, (c) variety of representations and (d) linking representations, by exploiting its capability for continuous modifications. By exploiting these opportunities in the context of the given open tasks, students were helped by the tools provided to develop a broader view of the concept of area than the typical view they would construct in a typical paper and pencil environment. 相似文献