全文获取类型
收费全文 | 3185篇 |
免费 | 50篇 |
国内免费 | 12篇 |
专业分类
化学 | 1475篇 |
晶体学 | 25篇 |
力学 | 127篇 |
数学 | 519篇 |
物理学 | 1101篇 |
出版年
2021年 | 35篇 |
2020年 | 51篇 |
2019年 | 52篇 |
2018年 | 73篇 |
2017年 | 50篇 |
2016年 | 79篇 |
2015年 | 59篇 |
2014年 | 90篇 |
2013年 | 129篇 |
2012年 | 126篇 |
2011年 | 153篇 |
2010年 | 131篇 |
2009年 | 108篇 |
2008年 | 142篇 |
2007年 | 145篇 |
2006年 | 116篇 |
2005年 | 114篇 |
2004年 | 108篇 |
2003年 | 92篇 |
2002年 | 107篇 |
2001年 | 50篇 |
2000年 | 47篇 |
1999年 | 29篇 |
1998年 | 35篇 |
1997年 | 42篇 |
1996年 | 44篇 |
1995年 | 27篇 |
1994年 | 32篇 |
1993年 | 28篇 |
1992年 | 34篇 |
1991年 | 32篇 |
1990年 | 35篇 |
1987年 | 27篇 |
1984年 | 45篇 |
1983年 | 36篇 |
1982年 | 37篇 |
1981年 | 38篇 |
1980年 | 35篇 |
1979年 | 32篇 |
1978年 | 30篇 |
1977年 | 60篇 |
1976年 | 37篇 |
1975年 | 29篇 |
1974年 | 42篇 |
1973年 | 32篇 |
1972年 | 35篇 |
1971年 | 26篇 |
1968年 | 27篇 |
1967年 | 39篇 |
1966年 | 27篇 |
排序方式: 共有3247条查询结果,搜索用时 15 毫秒
1.
Eugene O. Kamenetskii 《Annalen der Physik》2020,532(3):1900423
The relationship between magnetoelectricity and electromagnetism is a subject of a strong interest and numerous discussions in microwave and optical wave physics and material sciences. The definition of the energy and momentum of the electromagnetic (EM) field in a magnetoelectric (ME) medium is not a trivial problem. The question of whether electromagnetism and magnetoelectricity can coexist without an extension of Maxwell's theory arises when the effects of EM energy propagation are studied and the group velocity of the waves in an ME medium is considered. The energy balance equation reveals unusual topological structure of fields in ME materials. Together with certain constraints on the constitutive parameters of a medium, definite constraints on the local field structure should be imposed. Analyzing the EM phenomena inside an ME material, the question “what kind of the near fields arising from a sample of such a material can be measured?” should be answered. The visualization of the ME states requires an experimental technique that is based on an effective coupling to the violation of spatial as well as temporal inversion symmetry. To observe the ME energy in a subwavelength region, it is necessary to assume the existence of first-principle near fields—the ME fields. These are non-Maxwellian near fields with specific properties of violation of spatial and temporal inversion symmetry. A particular interest to the ME fields arises in studies of metamaterials with “artificial-atoms” ME elements. 相似文献
2.
Konyukhov V. K. Stepanov E. V. Borisov S. K. 《Bulletin of the Lebedev Physics Institute》2020,47(2):59-63
Bulletin of the Lebedev Physics Institute - Abstract—The self-similarity effect during rarefied water vapor flow between two finite-volume vessels is repeatedly recorded with a similarity... 相似文献
3.
Ishchenko A. N. Afanas’eva S. A. Belov N. N. Burkin V. V. Zakharov V. M. Zykova A. I. Sammel’ A. Yu. Skosyrskii A. B. Stepanov E. Yu. Tabachenko A. N. Chupashev A. V. Ushakova O. V. Khabibullin M. V. Yugov N. T. 《Technical Physics》2020,65(6):925-934
Technical Physics - The ballistic resistance of a combined cermet material based on a high-hardness ceramic bound with an intermetallide on a high-strength metal substrate, (TiB2 + NiTi) + Ti, is... 相似文献
4.
5.
6.
Panpan Li Quanbin Liang Eugene Yau-Hin Hong Chin-Yiu Chan Yat-Hin Cheng Ming-Yi Leung Mei-Yee Chan Kam-Hung Low Hongbin Wu Vivian Wing-Wah Yam 《Chemical science》2020,11(42):11601
A class of acceptor–donor–acceptor chromophoric small-molecule non-fullerene acceptors, 1–4, with difluoroboron(iii) β-diketonate (BF2bdk) as the electron-accepting moiety has been developed. Through the variation of the central donor unit and the modification on the peripheral substituents of the terminal BF2bdk acceptor unit, their photophysical and electrochemical properties have been systematically studied. Taking advantage of their low-lying lowest unoccupied molecular orbital energy levels (from −3.65 to −3.72 eV) and relatively high electron mobility (7.49 × 10−4 cm2 V−1 s−1), these BF2bdk-based compounds have been employed as non-fullerene acceptors in organic solar cells with maximum power conversion efficiencies of up to 4.31%. Moreover, bistable resistive memory characteristics with charge-trapping mechanisms have been demonstrated in these BF2bdk-based compounds. This work not only demonstrates for the first time the use of a boron(iii) β-diketonate unit in constructing non-fullerene acceptors, but also provides more insights into designing organic materials with multi-functional properties.Boron(iii) β-diketonates have been demonstrated to serve as multi-functional materials in NFA-based OPVs and organic resistive memories. 相似文献
7.
E. I. Bezgomonova A. R. Rasulov G. V. Stepanov 《Russian Journal of Physical Chemistry B, Focus on Physics》2015,9(7):1026-1031
The isochoric heat capacity of the n-hexane–water system was studied on an adiabatic calorimeter at 300–600 K and molar fractions of water of 0.256–0.935 in a wide range of densities. The experimental critical curves of the liquid–vapor phase equilibrium were described by the equation corresponding to the theory of critical phenomena. 相似文献
8.
From Spherical to Leaf‐Like Morphologies: Tunable Supramolecular Assembly of Alkynylgold(I) Complexes through Variations of the Alkyl Chain Length 下载免费PDF全文
Eugene Yau‐Hin Hong Dr. Hok‐Lai Wong Prof. Vivian Wing‐Wah Yam 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(15):5732-5735
A series of luminescent polynuclear alkynylgold(I) complexes with different lengths of alkyl chains attached at the N‐heterocyclic carbene moieties has been synthesised and demonstrated to display intriguing self‐assembly behaviours through a cooperative growth mechanism. Variation of the alkyl chain length was found to cause drastic morphological differences in the aggregates and to strongly affect the thermodynamic parameters as revealed by the nucleation–elongation model. 相似文献
9.
10.