全文获取类型
收费全文 | 128749篇 |
免费 | 6304篇 |
国内免费 | 6050篇 |
专业分类
化学 | 59245篇 |
晶体学 | 1490篇 |
力学 | 9844篇 |
综合类 | 412篇 |
数学 | 37993篇 |
物理学 | 32119篇 |
出版年
2023年 | 593篇 |
2022年 | 1074篇 |
2021年 | 1383篇 |
2020年 | 1624篇 |
2019年 | 1702篇 |
2018年 | 11741篇 |
2017年 | 11610篇 |
2016年 | 8010篇 |
2015年 | 2744篇 |
2014年 | 2849篇 |
2013年 | 3549篇 |
2012年 | 7308篇 |
2011年 | 14127篇 |
2010年 | 8614篇 |
2009年 | 8841篇 |
2008年 | 9585篇 |
2007年 | 11555篇 |
2006年 | 2866篇 |
2005年 | 3416篇 |
2004年 | 3185篇 |
2003年 | 3403篇 |
2002年 | 2457篇 |
2001年 | 1564篇 |
2000年 | 1342篇 |
1999年 | 1017篇 |
1998年 | 854篇 |
1997年 | 762篇 |
1996年 | 758篇 |
1995年 | 631篇 |
1994年 | 528篇 |
1993年 | 534篇 |
1992年 | 457篇 |
1991年 | 465篇 |
1990年 | 456篇 |
1989年 | 416篇 |
1988年 | 346篇 |
1987年 | 357篇 |
1986年 | 354篇 |
1985年 | 378篇 |
1984年 | 347篇 |
1982年 | 334篇 |
1979年 | 353篇 |
1978年 | 366篇 |
1977年 | 340篇 |
1976年 | 421篇 |
1975年 | 375篇 |
1974年 | 400篇 |
1973年 | 423篇 |
1972年 | 386篇 |
1971年 | 343篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Wu Shang-Zhuo Yu Qiang Li Yue-Hua Cui Guang-Hua 《Research on Chemical Intermediates》2021,47(2):835-851
Research on Chemical Intermediates - Combination of three aromatic carboxylic acids (5-nitroisophthalic acid (H2nip), 2,6-naphthalenedicarboxylic acid (H2ndc), tetrabromoterephthalic acid (H2tbta))... 相似文献
22.
Yuwei Wang Jia-Jun Yan Shengnan Hu Prof. David James Young Prof. Hong-Xi Li Prof. Zhi-Gang Ren 《化学:亚洲杂志》2021,16(18):2681-2686
A photoluminescent bimetallic cluster [Ag10Cu6(bdppthi)2(C≡CPh)12(MeOH)2(H2O)](ClO4)4 ( 1 , bdppthi=N,N’-bis(diphenylphosphanylmethyl)-tetrahydroimidazole} was synthesized from the PNNP type ligand bdppthi generated in-situ. Upon excitation at 365 nm, 1 exhibited strong phosphorescent emission at 630 nm, which was selectively quenched by NH3 in air or water. The sensing of NH3 was rapid and recoverable, with detection limits of 53 ppm (v/v) in N2 and 21 μmol/L (0.36 ppm, w/w) for NH3 ⋅ H2O in water. Cluster 1 could potentially serve as a bifunctional chemical sensor for the efficient detection of ammonia in waste-gas and waste-water. 相似文献
23.
24.
25.
We investigate terahertz radiation(T-rays) from a pentacene organic diode at room temperature. The quantum chemistry calculation for frequency-related Huang–Rhys factor of pentacene is also carried out. The results demonstrate that the T-rays can come from a bending vibration of pentacene skeleton after the energy of pentacene exciton transferring to the vibrational excited state via electron–phonon coupling. Frequency and natural bond orbital analytics of pentacene and its derivatives are performed in order to explain the result and develop new materials to get higher emission. This work provides a new way to produce T-rays with a simple device at room temperature. 相似文献
26.
27.
28.
29.
Sulfur hexafluoride (SF6) is considered as a potent greenhouse gas, whose effective degradation is challenging. Here we report a computational study on the nucleophilic activation of sulfur hexafluoride by N-heterocyclic carbenes and N-heterocyclic olefins. The result shows that the activation of SF6 is both thermodynamically and kinetically favorable at mild condition using NHOs with fluoro-substituted azolium and sulfur pentafluoride anion being formed. The Gibbs free energy barrier during the activation of SF6 has a linear relationship with the energy of HOMO of substrates, which could be a guideline for applying those compounds that feature higher energy in HOMO to activate SF6 in high efficiency. 相似文献
30.
Guo Yan Li Zhuang Wei Yuxi Zhang Xinxu Shi Kexin 《Journal of Solid State Electrochemistry》2022,26(4):1051-1065
Journal of Solid State Electrochemistry - Polyvinylpyrrolidone (PVP) and graphene (G)-modified iron oxides (Fe2O3-PVP-G) are prepared by a simple hydrothermal reaction. Their morphology and... 相似文献