全文获取类型
收费全文 | 3898篇 |
免费 | 705篇 |
国内免费 | 333篇 |
专业分类
化学 | 2582篇 |
晶体学 | 54篇 |
力学 | 287篇 |
综合类 | 17篇 |
数学 | 397篇 |
物理学 | 1599篇 |
出版年
2024年 | 9篇 |
2023年 | 107篇 |
2022年 | 116篇 |
2021年 | 161篇 |
2020年 | 159篇 |
2019年 | 155篇 |
2018年 | 148篇 |
2017年 | 118篇 |
2016年 | 211篇 |
2015年 | 187篇 |
2014年 | 219篇 |
2013年 | 294篇 |
2012年 | 378篇 |
2011年 | 369篇 |
2010年 | 249篇 |
2009年 | 218篇 |
2008年 | 243篇 |
2007年 | 224篇 |
2006年 | 216篇 |
2005年 | 178篇 |
2004年 | 130篇 |
2003年 | 104篇 |
2002年 | 83篇 |
2001年 | 72篇 |
2000年 | 82篇 |
1999年 | 69篇 |
1998年 | 64篇 |
1997年 | 52篇 |
1996年 | 55篇 |
1995年 | 52篇 |
1994年 | 28篇 |
1993年 | 40篇 |
1992年 | 39篇 |
1991年 | 23篇 |
1990年 | 21篇 |
1989年 | 15篇 |
1988年 | 11篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 10篇 |
1984年 | 1篇 |
1983年 | 6篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有4936条查询结果,搜索用时 15 毫秒
131.
132.
Jiang Yuan Jinming Duan Wei Li Christopher P. Saint Dennis Mulcahy 《Chromatographia》2017,80(2):247-257
133.
<正>Two new terpenes,wilfornine H(1) and triptobenzene Q(2) were isolated from Tripterygium wilfordii,as well as 11 terpenes. Their structures were elucidated by spectroscopic methods.Compounds 5,9-13 showed significant immunosuppressive activities. 相似文献
134.
Cornelius von Morze Douglas A.C. Kelley Timothy M. Shepherd Suchandrima Banerjee Duan Xu Christopher P. Hess 《Magnetic resonance imaging》2010
Ventral and rostral regions of the brain are of emerging importance for the MRI characterization of early dementia, traumatic brain injury and epilepsy. Unfortunately, standard single-shot echo planar diffusion-weighted imaging of these regions at high fields is contaminated by severe imaging artifacts in the vicinity of air–tissue interfaces. To mitigate these artifacts and improve visualization of the temporal and frontal lobes at 7 T, we applied a reduced field-of-view strategy, enabled by outer volume suppression (OVS) with novel quadratic phase radiofrequency (RF) pulses, combined with partial Fourier and parallel imaging methods. The new acquisition greatly reduced the level of artifacts in six human subjects (including four patients with early symptoms of dementia). 相似文献
135.
136.
137.
Yan Yang Liu-Ting Yan Xu-Jian Luo Rong-Huan Qin Wen-Gui Duan 《Supramolecular chemistry》2013,25(11):810-818
Three novel coordination polymers, [Co(NH2-Aip)(H2Bibim)] n (1), [Co(NH2-Aip)(HBibimop)] n √ nH2O (2) and [Mn(NH2-Aip) √ H2O] n √ 2nH2O (3) with NH2-Aip and similar benzimidazole derivative ligands (NH2-Aip = 5-aminoisophthalic acid, H2Bibim = 2,2′-bibenzimidazole and HBibimop = 1,3-bis(benzimidazol-2-yl)-2-oxapropane), have been synthesised under hydrothermal conditions and structurally characterised by single-crystal X-ray diffraction analysis, elemental analysis and IR spectroscopy. 5-Aminoisophthalic acid ligand adopts μ2-, μ3- and μ4-bridge coordination fashion and benzimidazole derivatives exist as terminal- and bridge-mode in complexes 1–3. The intricate hydrogen bonds and π–π stacking interactions in supramolecular framework are discussed. Using the combination of ultraviolet–visible absorption titration and fluorescence spectra, the experimental results show that complexes 1 and 2 bind to DNA in an intercalative mode and their DNA-binding constants (K b ) are also found. 相似文献
138.
Fu-Jun Duan Jin-Chang Ding Hong-Juan Deng Ding-Ben Chen Jiu-Xi Chen Miao-Chang Liu Hua-Yue Wu 《中国化学快报》2013,24(9):793-796
An efficient and facile method for the synthesis of N-substituted pyrroles in moderate to good yields by the Paal–Knorr reaction of γ-diketones with amines in the presence of β-cyclodextrin in aqueous media has been developed.Moreover,this process tolerated diamines(e.g.,para-,meta- or orthophenylenediamine)to construct bis-pyrrole or mono-pyrrole derivates.β-Cyclodextrin can be recovered easily after the reactions and reused without evident loss in activity. 相似文献
139.
The azido sugar,GalNAz,was successfully used for imaging and perturbing protein glycosylation in triple-negative breast cancer cell line,MDA-MB-231.After the incorporation of GalNAz in the triple-negative breast cancer cell line,the tumorigenicity of these cells was decreased.Results from gene analysis and drug treatment suggest that the tumorigenicity decrease may be attributed to the reduction of cancer stem cell population.Possible mechanisms of GalNAz induced cancer stem cells(CSCs) proportion change are discussed. 相似文献
140.