全文获取类型
收费全文 | 8570篇 |
免费 | 1653篇 |
国内免费 | 915篇 |
专业分类
化学 | 5727篇 |
晶体学 | 88篇 |
力学 | 718篇 |
综合类 | 65篇 |
数学 | 1130篇 |
物理学 | 3410篇 |
出版年
2024年 | 7篇 |
2023年 | 178篇 |
2022年 | 200篇 |
2021年 | 270篇 |
2020年 | 347篇 |
2019年 | 316篇 |
2018年 | 286篇 |
2017年 | 280篇 |
2016年 | 420篇 |
2015年 | 407篇 |
2014年 | 449篇 |
2013年 | 638篇 |
2012年 | 744篇 |
2011年 | 829篇 |
2010年 | 557篇 |
2009年 | 534篇 |
2008年 | 624篇 |
2007年 | 480篇 |
2006年 | 522篇 |
2005年 | 375篇 |
2004年 | 314篇 |
2003年 | 249篇 |
2002年 | 219篇 |
2001年 | 190篇 |
2000年 | 181篇 |
1999年 | 169篇 |
1998年 | 175篇 |
1997年 | 158篇 |
1996年 | 166篇 |
1995年 | 136篇 |
1994年 | 116篇 |
1993年 | 111篇 |
1992年 | 90篇 |
1991年 | 69篇 |
1990年 | 75篇 |
1989年 | 61篇 |
1988年 | 44篇 |
1987年 | 34篇 |
1986年 | 34篇 |
1985年 | 22篇 |
1984年 | 18篇 |
1983年 | 14篇 |
1982年 | 15篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1975年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
以过渡金属为催化衬底的化学气相沉积法(Chemical Vapor Deposition,CVD)已经可以制备与机械剥离样品相媲美的石墨烯,是实现石墨烯工业应用的关键技术之一。原子尺度理论研究能够帮助我们深刻理解石墨烯生长机理,为实验现象提供合理的解释,并有可能成为将来实验设计的理论指导。本文从理论计算的角度,总结了各种金属衬底在石墨烯CVD生长过程中的各种作用与相应的机理,包括在催化碳源裂解、降低石墨烯成核密度等,催化加快石墨烯快速生长,修复石墨烯生长过程中产生的缺陷,控制外延生长石墨烯的晶格取向,以及在降温过程中石墨烯褶皱与金属表面台阶束的形成过程等。在本文最后,我们对当前石墨烯生长领域中亟需解决的理论问题进行了深入探讨与展望。 相似文献
2.
Xu Yifan Zhang Hehe Ding Tangjing Tian Ruiqi Sun Dongmei Wang Ming-Sheng Zhou Xiaosi 《中国科学:化学(英文版)》2022,65(9):1807-1816
Science China Chemistry - Due to their enormous potential for large-scale energy storage, rechargeable potassium-ion batteries have been widely researched and developed. However, the drastic volume... 相似文献
3.
Potential Analysis - The purpose of this paper is to provide necessary and sufficient conditions of the boundedness for singular integrals on the local Hardy space and its dual. Particularly the... 相似文献
4.
A complete manifold is said to be nonparabolic if it does admit a positive Green’s function. To ?nd a sharp geometric criterion for the parabolicity/nonparbolicity is an attractive question inside the function theory on Riemannian manifolds. This paper devotes to proving a criterion for nonparabolicity of a complete manifold weakened by the Ricci curvature. For this purpose, we shall apply the new Laplacian comparison theorem established by the ?rst author to show the existence of a non-constant bounded subharmonic function. 相似文献
5.
Ding Q. Yao M. Wu Sh. Zeng M. Xue N. Wu D. Xu J. 《Journal of Applied Spectroscopy》2022,89(4):712-718
Journal of Applied Spectroscopy - Based on partial least squares (PLS) analysis, the effects of different smoothing points and different preprocessing methods on the accuracy and precision of the... 相似文献
6.
7.
Zi-Han Li Yuan-Qi Zhai Dr. Wei-Peng Chen Dr. You-Song Ding Prof. Dr. Yan-Zhen Zheng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(71):16219-16224
Eight-coordinated DyIII centres with D6h symmetry are expected to act as high-performance single-molecule magnets (SMMs) due to the simultaneous fulfilment of magnetic axiality and a high coordination number (a requisite for air stability). But the experimental realization is challenging due to the requirement of six coordinating atoms in the equatorial plane of the hexagonal bipyramid; this is usually too crowded for the central DyIII ion. Here a hexaaza macrocyclic Schiff base ligand and finetuned axial alkoxide/phenol-type ligands are used to show that a family of hexagonal bipyramidal DyIII complexes can be isolated. Among them, three complexes possess nearly perfect D6h local symmetry. The highest effective magnetic reversal barrier is found at 1338(3) K and an open hysteresis temperature of 6 K at the field sweeping rate of 1.2 mT s−1; this represents a new record for D6h SMMs. 相似文献
8.
Fei Zhang GaoShan Huang XiaoFei Nie Xin Cao Zhe Ma Fei Ding ZengFeng Di HongLou Zhen YongFeng Mei 《Physics letters. A》2019,383(24):2938-2942
In this study, we investigate the modulation of energy band in 3D self-assembled nanomembranes containing GaAs/Al0.26Ga0.74As quantum wells (QWs). Photoluminescence (PL) characterizations demonstrate that the self-assembled structures have different optical transition properties and the modulation of the energy band is thus realized. Detailed spectral analyses disclose that the small strain change in structures with different curvatures cannot cause remarkable change in energy bands in Al0.26Ga0.74As layer. On the other hand, the optical transitions of GaAs QW layer is influenced by the strain evolution in term of light emission intensity. We also find the first order Stark effect in rolled-up nanomembrane with diameter of 150 μm, which is closely connected with the coupling effect between the deformation potential and the piezoelectric potential. Our work may pave a way for the fabrication of high performance rolled-QW infrared photo-detectors. 相似文献
9.
Ding Wenwen He Yongjia Lu Linnu Rao Meijuan Wang Fazhou 《Journal of Thermal Analysis and Calorimetry》2019,135(4):2009-2018
Journal of Thermal Analysis and Calorimetry - The present task is to investigate the influence of iron on the mineral composition and microstructure of the phase Q (C20A13M3S3, in the text below... 相似文献
10.
Let X, Y be Polish spaces, , . We say A is universal for Γ provided that each x‐section of A is in Γ and each element of Γ occurs as an x‐section of A. An equivalence relation generated by a set is denoted by , where . The following results are shown:
- (1) If A is a set universal for all nonempty closed subsets of Y, then is a equivalence relation and .
- (2) If A is a set universal for all countable subsets of Y, then is a equivalence relation, and
- (i) and ;
- (ii) if , then ;
- (iii) if every set is Lebesgue measurable or has the Baire property, then .
- (iv) for , if every set has the Baire property, and E is any equivalence relation, then .