全文获取类型
收费全文 | 124876篇 |
免费 | 8432篇 |
国内免费 | 7051篇 |
专业分类
化学 | 59862篇 |
晶体学 | 1419篇 |
力学 | 9340篇 |
综合类 | 464篇 |
数学 | 37086篇 |
物理学 | 32188篇 |
出版年
2024年 | 108篇 |
2023年 | 910篇 |
2022年 | 1474篇 |
2021年 | 1695篇 |
2020年 | 1925篇 |
2019年 | 1924篇 |
2018年 | 11679篇 |
2017年 | 11543篇 |
2016年 | 8233篇 |
2015年 | 3138篇 |
2014年 | 3254篇 |
2013年 | 4033篇 |
2012年 | 8205篇 |
2011年 | 14869篇 |
2010年 | 8898篇 |
2009年 | 9019篇 |
2008年 | 9893篇 |
2007年 | 11675篇 |
2006年 | 3102篇 |
2005年 | 3646篇 |
2004年 | 3284篇 |
2003年 | 3408篇 |
2002年 | 2429篇 |
2001年 | 1460篇 |
2000年 | 1297篇 |
1999年 | 1137篇 |
1998年 | 920篇 |
1997年 | 787篇 |
1996年 | 848篇 |
1995年 | 716篇 |
1994年 | 582篇 |
1993年 | 488篇 |
1992年 | 418篇 |
1991年 | 408篇 |
1990年 | 334篇 |
1989年 | 297篇 |
1988年 | 247篇 |
1987年 | 208篇 |
1986年 | 197篇 |
1985年 | 162篇 |
1984年 | 101篇 |
1983年 | 85篇 |
1982年 | 81篇 |
1981年 | 68篇 |
1980年 | 68篇 |
1979年 | 57篇 |
1978年 | 44篇 |
1914年 | 45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 390 毫秒
51.
Cuixia Cui Yong Gao Dr. Jun Li Chao Yang Meng Liu Prof. Dr. Huile Jin Prof. Dr. Zhenhai Xia Prof. Dr. Liming Dai Prof. Dr. Yong Lei Prof. Dr. Jichang Wang Prof. Dr. Shun Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(20):8002-8007
Although tremendous efforts have been devoted to understanding the origin of boosted charge storage on heteroatom-doped carbons, none of the present studies has shown a whole landscape. Herein, by both experimental evidence and theoretical simulation, it is demonstrated that heteroatom doping not only results in a broadened operating voltage, but also successfully promotes the specific capacitance in aqueous supercapacitors. In particular, the electrolyte cations adsorbed on heteroatom-doped carbon can effectively inhibit hydrogen evolution reaction, a key step of water decomposition during the charging process, which broadens the voltage window of aqueous electrolytes even beyond the thermodynamic limit of water (1.23 V). Furthermore, the reduced adsorption energy of heteroatom-doped carbon consequently leads to more stored cations on the heteroatom-doped carbon surface, thus yielding a boosted charge storage performance. 相似文献
52.
53.
54.
55.
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
56.
57.
58.
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
59.
Shi-Chun Mao Zhaohui Zhang Jiansen Gao Zhen-Sen Wu 《Waves in Random and Complex Media》2019,29(1):54-62
A solution to the problem of Gaussian beam scattering by an anisotropically coated circular cylinder is presented. The incident Gaussian beam source is expanded as an approximate expression in the simple form with a Tayor’s series. The transmitted field in the anisotropically coated region is expressed as a infinite summation of eigen plane waves with different polar angles. The unknown coefficients of the scattered fields are obtained with the aid of the boundary conditions. The infinite series can be truncated under the prerequisite of achieving the solution convergence. Only the case of transverse-electric polarization is discussed. The similar formulation of transverse-magnetic polarization can be obtained by adopting the similar method. Some numerical results are presented and discussed. The result is in agreement with that available as expected when the Gaussian beam degenerates to a plane wave incidence case. 相似文献
60.
Several phenoxy-imine ligands bearing o-trityl group in phenoxy moiety RN=CHArOH (Ar = C6H2(CPh3)tBu, R = 2,6-Me2C6H3 ( L 1 H ); 2,6-iPr2C6H3 ( L 2 H ); 3,5-(CF3)2C6H3 ( L 3 H ); 3,5-(OMe)2C6H3 ( L 4 H ); CHPh2 ( L 5 H ); CPh3 ( L 6 H )) were synthesized and characterized by1H NMR and 13C NMR spectroscopy. The vanadium complexes based on these ligands LVCl2(THF)2 ( 1–6 ) were synthesized via conventional transmetalation reaction in moderate to high yields. Complexes 1–6 were fully characterized by FT-IR, elemental analyses and the molecular structures of 1 , 2 ·H2O, (2 ·H2O ) 2 (μ-Cl) 2 , 4 , and 5 were confirmed by X-ray crystallographic analysis in which the six-coordinated vanadium centers are in a typical octahedral geometry. Upon activation with Et2AlCl in toluene, complexes 1–6 showed high activities in ethylene polymerization affording polymers with moderate molecular weight (5.9–11.8 × 104 Da). Moreover, in hexane or CH2Cl2, 1–6 /Et2AlCl exhibited enhanced activities. When activated with MAO or MMAO in toluene, these complexes showed relatively low activities but afforded polymers with ultra-high molecular weight (up to 3.30 × 106 Da). 1–6 /Et2AlCl also showed high activities in ethylene/1-hexene copolymerization at room temperature giving moderate molecular-weight polymers (6.5–11.4 × 104 Da) with co-monomer incorporation being of 6.0 ~ 7.8%. 相似文献