全文获取类型
收费全文 | 1607篇 |
免费 | 299篇 |
国内免费 | 334篇 |
专业分类
化学 | 867篇 |
晶体学 | 20篇 |
力学 | 146篇 |
综合类 | 3篇 |
数学 | 409篇 |
物理学 | 795篇 |
出版年
2023年 | 29篇 |
2022年 | 46篇 |
2021年 | 53篇 |
2020年 | 51篇 |
2019年 | 36篇 |
2018年 | 36篇 |
2017年 | 64篇 |
2016年 | 71篇 |
2015年 | 82篇 |
2014年 | 119篇 |
2013年 | 172篇 |
2012年 | 235篇 |
2011年 | 195篇 |
2010年 | 147篇 |
2009年 | 180篇 |
2008年 | 119篇 |
2007年 | 131篇 |
2006年 | 114篇 |
2005年 | 83篇 |
2004年 | 47篇 |
2003年 | 41篇 |
2002年 | 44篇 |
2001年 | 34篇 |
2000年 | 19篇 |
1999年 | 31篇 |
1998年 | 21篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1971年 | 1篇 |
1923年 | 1篇 |
排序方式: 共有2240条查询结果,搜索用时 15 毫秒
1.
Acta Mechanica Sinica - 相似文献
2.
3.
Biodegradable poly(butylene succinate-co-lactate) (PBSL)/starch blends that contain various amounts of starch were prepared. In addition, luffa fiber (LF) and kenaf fiber (KF) were incorporated, individually, into PBSL/starch (70/30) blend to achieve biocomposites. The LF and KF were treated with NaOH(aq) prior to their addition to the blend. The Young's modulus and flexural modulus of PBSL increased with the addition of starch and increased further after the formation of the biocomposites. The highest Young's modulus increment, which was found in the KF-added system, was up to a 2.2-fold increase compared with neat PBSL. The tensile/flexural/impact strength of PBSL declined after the formation of the blends. With the further addition of LF/KF, the said properties leveled off. The blends exhibited higher complex viscosity and dynamic storage modulus in the melt state than the neat PBSL, and the values further increased in the biocomposites. The crystallization temperature of PBSL slightly decreased in the blends. By contrast, the biocomposites showed an increment in PBSL crystallization temperature, from 73.0 °C (PBSL) to 75.3 °C (KF-added composite), thereby confirming the surface nucleation effect of LF/KF. The blends showed a higher degree of water absorption than PBSL. The formation of biocomposites led to an even higher degree of water absorption. The current approach of including LF/KF in the PBSL/starch blend to enhance the rigidity and biodegradability was advantageous in expanding the applications of PBSL. 相似文献
4.
5.
6.
《Arabian Journal of Chemistry》2020,13(3):4564-4576
Versatile graphdiyne (GDY) substrate has been modified by numerous transition metals and resulting composites showed excellent photo/electro-catalytic performance. However, GDY materials modified by actinides that are stockpiled waste product due to large-scale use in nuclear industry, are particularly scarce and remains great challenge. To deeply understand the structural properties, GDY complexating actinyl (AnmO2)n+ (An = U, Np, Pu; m = VI, V) species with its atomistic pore was investigated by relativistic density functional theory (DFT). The GDY pore was found suitable to hold actinyl species, by forming organometallic AnC dative bonds. This chemical coupling interaction was further confirmed by quantum theory of atoms-in-molecule and electronic structure calculations. The GDY-uranyl(V), for instance, shows a π(UC) bonding HOMO, which is anticipated to improve electron transfer between ligand and metal. Orbital structures and compositions of complexes suggest their implication towards catalysis, which were further corroborated by calculations on redox potentials of GDY-actinyl complexes. Hence, our results show the potential applications of GDY complexating actinyl species towards novel catalytic surfaces. 相似文献
7.
8.
9.
10.
基于密度泛函的第一原理赝势平面波方法,计算晶体结构、电子结构和光学性质,研究硫钒铜矿化合物Cu3VS4、Cu3NbS4和Cu3TaS4的电子输运及电致变色特性,探讨作为透明半导体材料应用于太阳能电池和电致变色器件的可能性.电子结构的计算表明这类化合物是间接带隙半导体,其电子能带的导带底和价带顶分别位于布里渊区的X点和R点.价带顶的电子本征态主要来自于Cu原子的d电子轨道,而导带底电子态主要来源于VB族元素原子的d电子轨道.能带结构、电荷布居分析、电子局域化函数和光吸收及反射谱的计算表明这些硫钒铜矿化合物属于极性共价半导体,具有较高的电荷迁移率和优良的电致变色特性,可应用于高效电致变色器件. 相似文献