全文获取类型
收费全文 | 91138篇 |
免费 | 2776篇 |
国内免费 | 3024篇 |
专业分类
化学 | 35168篇 |
晶体学 | 1058篇 |
力学 | 7464篇 |
综合类 | 150篇 |
数学 | 33250篇 |
物理学 | 19848篇 |
出版年
2024年 | 49篇 |
2023年 | 310篇 |
2022年 | 541篇 |
2021年 | 599篇 |
2020年 | 667篇 |
2019年 | 709篇 |
2018年 | 10917篇 |
2017年 | 10744篇 |
2016年 | 6707篇 |
2015年 | 1592篇 |
2014年 | 1184篇 |
2013年 | 1427篇 |
2012年 | 4936篇 |
2011年 | 11641篇 |
2010年 | 6568篇 |
2009年 | 6875篇 |
2008年 | 7465篇 |
2007年 | 9484篇 |
2006年 | 978篇 |
2005年 | 1995篇 |
2004年 | 2103篇 |
2003年 | 2454篇 |
2002年 | 1549篇 |
2001年 | 757篇 |
2000年 | 639篇 |
1999年 | 434篇 |
1998年 | 386篇 |
1997年 | 270篇 |
1996年 | 351篇 |
1995年 | 219篇 |
1994年 | 186篇 |
1993年 | 196篇 |
1992年 | 129篇 |
1991年 | 149篇 |
1990年 | 103篇 |
1989年 | 92篇 |
1988年 | 82篇 |
1987年 | 79篇 |
1986年 | 83篇 |
1985年 | 68篇 |
1984年 | 56篇 |
1983年 | 49篇 |
1982年 | 45篇 |
1981年 | 42篇 |
1980年 | 48篇 |
1979年 | 47篇 |
1914年 | 45篇 |
1912年 | 40篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 515 毫秒
21.
22.
23.
24.
Zenon Moszner 《Aequationes Mathematicae》2018,92(4):617-625
We give the form of the output function in Ginsburg’s machine in which the input and output dictionaries are abelian groups and the transition function is of a special form. 相似文献
25.
26.
Kai He Tsegaye TadesseTsega Xi Liu Jiantao Zai Xin‐Hao Li Xuejiao Liu Wenhao Li Nazakat Ali Xuefeng Qian 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(34):12029-12035
The modulation of electron density is an effective option for efficient alternative electrocatalysts. Here, p‐n junctions are constructed in 3D free‐standing FeNi‐LDH/CoP/carbon cloth (CC) electrode (LDH=layered double hydroxide). The positively charged FeNi‐LDH in the space‐charge region can significantly boost oxygen evolution reaction. Therefore, the j at 1.485 V (vs. RHE) of FeNi‐LDH/CoP/CC achieves ca. 10‐fold and ca. 100‐fold increases compared to those of FeNi‐LDH/CC and CoP/CC, respectively. Density functional theory calculation reveals OH? has a stronger trend to adsorb on the surface of FeNi‐LDH side in the p‐n junction compared to individual FeNi‐LDH further verifying the synergistic effect in the p‐n junction. Additionally, it represents excellent activity toward water splitting. The utilization of heterojunctions would open up an entirely new possibility to purposefully regulate the electronic structure of active sites and promote their catalytic activities. 相似文献
27.
A new asymmetric Salamo‐based ligand H2L was synthesized using 3‐tert‐butyl‐salicylaldehyde and 6‐methoxy‐2‐[O‐(1‐ethyloxyamide)]‐oxime‐1‐phenol. By adjusting the ratio of the ligand H2L and Cu (II), Co (II), and Ni (II) ions, mononuclear, dinuclear, and trinuclear transition metal (II) complexes, [Cu(L)], [{Co(L)}2], and [{Ni(L)(CH3COO)(CH3CH2OH)}2Ni] with the ligand H2L possessing completely different coordination modes were obtained, respectively. The optical spectra of ligand H2L and its Cu (II), Co (II) and Ni (II) complexes were investigated. The Cu (II) complex is a mononuclear structure, and the Cu (II) atom is tetracoordinated to form a planar quadrilateral structure. The Co (II) complex is dinuclear, and the two Co (II) atoms are pentacoordinated and have coordination geometries of distorted triangular bipyramid. The Ni (II) complex is a trinuclear structure, and the terminal and central Ni (II) atoms are all hexacoordinated, forming distorted octahedral geometries. Furthermore, optical properties including UV–Vis, IR, and fluorescence of the Cu (II), Co (II), and Ni (II) complexes were investigated. Finally, the antibacterial activities of the Cu (II), Co (II), and Ni (II) complexes were explored. According to the experimental results, the inhibitory effect was found to be enhanced with increasing concentrations of the Cu (II), Co (II), and Ni (II) complexes. 相似文献
28.
29.
30.