全文获取类型
收费全文 | 50795篇 |
免费 | 6312篇 |
国内免费 | 3737篇 |
专业分类
化学 | 26273篇 |
晶体学 | 269篇 |
力学 | 2608篇 |
综合类 | 374篇 |
数学 | 15147篇 |
物理学 | 16173篇 |
出版年
2023年 | 543篇 |
2022年 | 878篇 |
2021年 | 1609篇 |
2020年 | 1560篇 |
2019年 | 1583篇 |
2018年 | 1114篇 |
2017年 | 1284篇 |
2016年 | 1783篇 |
2015年 | 1743篇 |
2014年 | 2408篇 |
2013年 | 4089篇 |
2012年 | 2705篇 |
2011年 | 3009篇 |
2010年 | 2567篇 |
2009年 | 3257篇 |
2008年 | 3355篇 |
2007年 | 3584篇 |
2006年 | 2840篇 |
2005年 | 2090篇 |
2004年 | 1687篇 |
2003年 | 1754篇 |
2002年 | 1572篇 |
2001年 | 1416篇 |
2000年 | 1120篇 |
1999年 | 937篇 |
1998年 | 938篇 |
1997年 | 653篇 |
1996年 | 708篇 |
1995年 | 621篇 |
1994年 | 585篇 |
1993年 | 576篇 |
1992年 | 490篇 |
1991年 | 335篇 |
1990年 | 265篇 |
1989年 | 226篇 |
1988年 | 243篇 |
1987年 | 270篇 |
1986年 | 267篇 |
1985年 | 407篇 |
1984年 | 303篇 |
1983年 | 177篇 |
1982年 | 339篇 |
1981年 | 509篇 |
1980年 | 454篇 |
1979年 | 499篇 |
1978年 | 403篇 |
1977年 | 302篇 |
1976年 | 254篇 |
1974年 | 90篇 |
1973年 | 168篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Liuhua Xie 《中国物理 B》2022,31(6):67103-067103
The effect of strain on charge density wave (CDW) order in $\alpha$-U is investigated within the framework of relativistic density-functional theory. The energetical stability of $\alpha$-U with CDW distortion is enhanced by the tensile strain along $a$ and $b$ axes, which is similar to the case of negative pressure and normal. However, the tensile strain along $c$ axis suppresses the energetical stability of CDW phase. This abnormal effect could be understood from the emergence of a new one-dimensional atomic chain along $c$ axis in $\alpha$-U. Furthermore, this effect is supported by the calculations of Fermi surface and phonon mode, in which the topological objects and the dynamical instability show opposite behaviors between strains along $a$/$b$ and $c$ axes. 相似文献
4.
Megha Sen Chowdhury Dr. Selcuk Gumus Dr. Sanchari Dasgupta Dr. Ishani Majumder Dr. Abir Bhattacharya Dr. Debasis Das Dr. Jayanta Mukhopadhyay Dr. Debosreeta Bose Dr. Saumya Dasgupta Dr. Yuksel Akinay Dr. Madhumita Mukhopadhyay 《ChemistryOpen》2022,11(6):e202200033
We report, for the first time, a detailed crystallographic study of the supramolecular arrangement for a set of zinc(II) Schiff base complexes containing the ligand 2,6-bis((E)-((2-(dimethylamino)ethyl)imino)methyl)-4-R-phenol], where R=methyl/tert-butyl/chloro. The supramolecular study acts as a pre-screening tool for selecting the compartmental ligand R of the Schiff base for effective binding with a targeted protein, bovine serum albumin (BSA). The most stable hexagonal arrangement of the complex [Zn − Me] (R=Me) stabilises the ligand with the highest FMO energy gap (ΔE=4.22 eV) and lowest number of conformations during binding with BSA. In contrast, formation of unstable 3D columnar vertebra for [Zn − Cl] (R=Cl) tend to activate the system with lowest FMO gap (3.75 eV) with highest spontaneity factor in molecular docking. Molecular docking analyses reported in terms of 2D LigPlot+ identified site A, a cleft of domains IB, IIIA and IIIB, as the most probable protein binding site of BSA. Arg144, Glu424, Ser428, Ile455 and Lys114 form the most probable interactions irrespective of the type of compartmental ligands R of the Schiff base whereas Arg185, Glu519, His145, Ile522 act as the differentiating residues with ΔG=−7.3 kcal mol−1. 相似文献
5.
Dariusz Marek Adam Domaski Joanna Domaska Jakub Szygua Tadeusz Czachrski Jerzy Klamka 《Entropy (Basel, Switzerland)》2021,23(5)
In this article, a way to employ the diffusion approximation to model interplay between TCP and UDP flows is presented. In order to control traffic congestion, an environment of IP routers applying AQM (Active Queue Management) algorithms has been introduced. Furthermore, the impact of the fractional controller and its parameters on the transport protocols is investigated. The controller has been elaborated in accordance with the control theory. The TCP and UDP flows are transmitted simultaneously and are mutually independent. Only the TCP is controlled by the AQM algorithm. Our diffusion model allows a single TCP or UDP flow to start or end at any time, which distinguishes it from those previously described in the literature. 相似文献
6.
7.
8.
9.
《中国物理 B》2021,30(5):56501-056501
Thermal expansion control is always an obstructive factor and challenging in high precision engineering field. Here,the negative thermal expansion of Nb F_3 and Nb OF_2 was predicted by first-principles calculation with density functional theory and the quasi-harmonic approximation(QHA). We studied the total charge density, thermal vibration, and lattice dynamic to investigate the thermal expansion mechanism. We found that the presence of O induced the relatively strong covalent bond in Nb OF_2, thus weakening the transverse vibration of F and O in Nb OF_2, compared with the case of Nb F_3.In this study, we proposed a way to tailor negative thermal expansion of metal fluorides by introducing the oxygen atoms.The present work not only predicts two NTE compounds, but also provides an insight on thermal expansion control by designing chemical bond type. 相似文献
10.