全文获取类型
收费全文 | 1901篇 |
免费 | 159篇 |
国内免费 | 9篇 |
专业分类
化学 | 1362篇 |
晶体学 | 24篇 |
力学 | 63篇 |
数学 | 248篇 |
物理学 | 372篇 |
出版年
2023年 | 13篇 |
2022年 | 16篇 |
2021年 | 60篇 |
2020年 | 49篇 |
2019年 | 82篇 |
2018年 | 61篇 |
2017年 | 45篇 |
2016年 | 105篇 |
2015年 | 73篇 |
2014年 | 78篇 |
2013年 | 142篇 |
2012年 | 119篇 |
2011年 | 110篇 |
2010年 | 86篇 |
2009年 | 87篇 |
2008年 | 104篇 |
2007年 | 117篇 |
2006年 | 95篇 |
2005年 | 69篇 |
2004年 | 66篇 |
2003年 | 55篇 |
2002年 | 51篇 |
2001年 | 47篇 |
2000年 | 35篇 |
1999年 | 28篇 |
1998年 | 11篇 |
1997年 | 12篇 |
1996年 | 13篇 |
1995年 | 11篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1988年 | 5篇 |
1987年 | 9篇 |
1985年 | 9篇 |
1984年 | 19篇 |
1983年 | 8篇 |
1981年 | 11篇 |
1980年 | 17篇 |
1979年 | 8篇 |
1978年 | 11篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1973年 | 6篇 |
1971年 | 6篇 |
1923年 | 4篇 |
1901年 | 4篇 |
1862年 | 8篇 |
排序方式: 共有2069条查询结果,搜索用时 25 毫秒
61.
62.
63.
64.
65.
Cover Picture: Open‐Pore Two‐Dimensional MFI Zeolite Nanosheets for the Fabrication of Hydrocarbon‐Isomer‐Selective Membranes on Porous Polymer Supports (Angew. Chem. Int. Ed. 25/2016) 下载免费PDF全文
Han Zhang Prof. Qiang Xiao Prof. Xianghai Guo Prof. Najun Li Prashant Kumar Neel Rangnekar Mi Young Jeon Prof. Shaeel Al‐Thabaiti Prof. Katabathini Narasimharao Prof. Sulaiman Nasir Basahel Prof. Berna Topuz Frank J. Onorato Prof. Christopher W. Macosko Prof. K. Andre Mkhoyan Prof. Michael Tsapatsis 《Angewandte Chemie (International ed. in English)》2016,55(25):7009-7009
66.
67.
Mahmoud Al‐Ktaifani Mwaffak Rukiah 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(9):m246-m250
In order to explore the potential propensity of the 1,1′‐methylenedipyridinium dication to form organic–inorganic hybrid ionic compounds by reaction with the appropriate halide metal salt, the organic–inorganic hybrid salts 1,1′‐methylenedipyridinium tetrachloridocuprate(II), (C11H12N2)[CuCl4], (I), and 1,1′‐methylenedipyridinium bis[tetrachloridoaurate(III)], (C11H12N2)[AuCl4]2, (II), were obtained by treatment of 1,1′‐methylenedipyridinium dichloride with CuCl2 and Na[AuCl4], respectively. Both hybrid salts were isolated as pure compounds, fully characterized by multinuclear NMR spectroscopy and their molecular structures confirmed by powder X‐ray diffraction studies. The crystal structures consist of discrete 1,1′‐methylenedipyridinium dications and [CuCl4]2− and [AuCl4]− anions for (I) and (II), respectively. As expected, the dications form a butterfly shape; the CuII centre of [CuCl4]2− has a distorted tetrahedral configuration and the AuIII centre of [AuCl4]− shows a square‐planar coordination. The ionic species of (I) and the dication of (II) each have twofold axial symmetry, while the two [AuCl4]− anions are located on a mirror‐plane site. Both crystal structures are stabilized by intermolecular C—H...Cl hydrogen bonds and also by Cl...π interactions. It is noteworthy that, while the average intermolecular centroid–centroid pyridinium ring distance in (I) is 3.643 (8) Å, giving strong evidence for noncovalent π–π ring interactions, for (II), the shortest centroid–centroid distance between pyridinium rings of 5.502 (9) Å is too long for any significant π–π ring interactions, which might be due to the bulk of the two [AuCl4]− anions. 相似文献
68.
J. J. Baker Khadilah H. M. Al Furaiji O. Tara Liyanage Dr. David J. D. Wilson Dr. Jason L. Dutton Dr. Caleb D. Martin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(6):1581-1587
The reactions of a monomeric borole and a dimeric borole with 2,3-dimethyl-1,3-butadiene and 1,3-cyclohexadiene were investigated. The monomeric borole reacted at ambient temperature whereas heat was required to crack the dimer to form the monomer and induce reactivity. 2,3-Dimethyl-1,3-butadiene reacts to give diverse products resulting from a cycloaddition process with the B−C moiety of the boroles acting as a dienophile, followed by rearrangements to furnish bicyclic species. For 1,3-cyclohexadiene, a [4+2] process is observed in which 1,3-cyclohexadiene serves as the dienophile and the boroles as the diene partner. The experimental results are corroborated with mechanistic theoretical calculations that indicate boroles can serve as either a diene or dienophile in cycloaddition reactions with dienes. 相似文献
69.
Shchur D. V. Zaginaichenko S. Yu. Veziroglu Ayfer Veziroglu T. N. Gavrylyuk N. A. Zolotarenko A. D. Gabdullin M. T. Ramazanov T. S. Zolotarenko Al. D. Zolotarenko An. D. 《Russian Physics Journal》2021,64(1):89-103
Russian Physics Journal - The paper presents the development of the statistical theory of phase transformation of lithium aluminum amide with the formation of ammonia. Free energies of phases are... 相似文献
70.
Prof. María Laura Uhrig Erwin W. Mora Flores Prof. Al Postigo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(29):7813-7825
Fluoroalkyl-substituted carbohydrates play relevant roles in diverse areas such as supramolecular chemistry, glycoconjugation, liquid crystals, and surfactants, with direct applications as wetting, antifreeze, and coating agents. In light of these promising applications, new methodologies for the late-stage incorporation of fluoroalkyl RF groups into carbohydrates and derivatives are herein presented as they are relevant to the synthetic carbohydrate community. Previously reviewed protocols for the installation of RF groups onto carbohydrates and derivatives will be succinctly summarized in the light of the new achievements. Fluoroalkyl-substituted iminosugars, on the other hand, are also interesting glycomimetic derivatives with prominent roles as glycosidases and glycosyltransferases inhibitors, as has recently been demonstrated. Also, they positively contribute to the study of sugar–protein interactions and enzyme mechanisms. New advances in the syntheses of fluoroalkyl-substituted iminosugars will also be presented here. 相似文献