全文获取类型
收费全文 | 741篇 |
免费 | 39篇 |
国内免费 | 2篇 |
专业分类
化学 | 621篇 |
晶体学 | 8篇 |
力学 | 7篇 |
数学 | 21篇 |
物理学 | 125篇 |
出版年
2023年 | 10篇 |
2022年 | 17篇 |
2021年 | 18篇 |
2020年 | 21篇 |
2019年 | 17篇 |
2018年 | 16篇 |
2017年 | 14篇 |
2016年 | 22篇 |
2015年 | 17篇 |
2014年 | 17篇 |
2013年 | 51篇 |
2012年 | 39篇 |
2011年 | 44篇 |
2010年 | 28篇 |
2009年 | 26篇 |
2008年 | 35篇 |
2007年 | 37篇 |
2006年 | 33篇 |
2005年 | 33篇 |
2004年 | 28篇 |
2003年 | 18篇 |
2002年 | 20篇 |
2001年 | 20篇 |
2000年 | 9篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 10篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1978年 | 14篇 |
1977年 | 10篇 |
1976年 | 7篇 |
1975年 | 10篇 |
1974年 | 6篇 |
1973年 | 6篇 |
排序方式: 共有782条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
45.
46.
Kentaro Mishiba Dr. Yuya Tanaka Prof. Dr. Munetaka Akita 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(17):5432-5438
Herein, we report the synthesis and electrochemical and photophysical properties of aromatic hydrocarbons having one or two dimesitylborylethynyl peripherals. The mono- ( 1 ) and diboryl compounds ( 2 ), readily prepared by nucleophilic substitution reaction, are fairly stable to air and moisture in the solid state. The inserted ethynediyl (C≡C) spacer cancels the steric hindrance between the bulky dimesitylboryl groups and aromatic rings, leading to effective π conjugation over the B−C≡C−Ar linkages, as revealed by cyclic voltammetry. Despite the small structural differences, the photophysical properties of the benzene, naphthalene, and anthracene derivatives are different. Virtually no emission was observed from the benzene derivatives, whereas the anthracene derivatives emitted with high quantum yields both in solution and in the solid state. Notably, the naphthalene derivatives showed aggregation-induced emission behavior. Unlike the common sterically congested triarylborane derivatives reported so far, the anthracene derivatives showed π–π*-type absorption and emission bands, which derive from efficient intramolecular orbital interactions between the boron centers and anthracene moieties, as supported by DFT calculations. As a result, the dimesitylborylethynyl substituents effectively lower the LUMO levels of the aromatic hydrocarbon parts, whereas the HOMO levels are almost unaffected, thereby leading to materials with controllable HOMO–LUMO gaps. 相似文献
47.
Mana Yuasa Ryuki Sumida Dr. Yuya Tanaka Prof. Dr. Michito Yoshizawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(10):e202104101
To explore new cavity functions, we herein employed cis-trans stereoisomers with a N=N, C=C, or C=N unit as guest indicators for a polyaromatic capsule. Thanks to the rigid, spherical cavity with a diameter of ∼1 nm, azobenzene and stilbene derivatives are quantitatively encapsulated by the capsule with 100 % cis-selectivity in water. The isomerization of the cis-azo compound is suppressed against heat and light in the cavity, due to the confinement effect. Furthermore, C,N-diphenyl imine derivatives are quantitatively encapsulated by the capsule in water and adopt an otherwise unstable cis-form. The polyaromatic cavity suppresses the hydrolysis of the imines in water, even at elevated temperature, due to the shielding effect. Accordingly, the properties of the cis-trans isomers could be largely altered through supramolecular manipulation. 相似文献
48.
Owing to marked advances in instrumentation in X-ray and neutron scattering the time-dependent pair correlation function, the Van Hove function, can now be determined by inelastic X-ray and neutron scattering measurements. The local dynamics of water in real space and time is visualised by this approach. We discuss how the dynamic properties, such as viscosity and diffusion, can be elucidated through the Van Hove function of water. 相似文献
49.
Atsushi Yashiro Dr. Yuya Tanaka Prof. Tomofumi Tada Prof. Shintaro Fujii Prof. Tomoaki Nishino Prof. Munetaka Akita 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(37):9666-9673
In this work, the design, synthesis, and single-molecule conductance of ethynyl- and butadiynyl-ruthenium molecular wires with thioether anchor groups [RS=n-C6H13S, p-tert-Bu−C6H4S), trans-{RS−(C≡C)n}2Ru(dppe)2 (n=1 ( 1R ), 2 ( 2R ); dppe: 1,2-bis(diphenylphosphino)ethane) and trans-(n-C6H13S−C≡C)2Ru{P(OMe)3}4 3hex ] are reported. Scanning tunneling microscope break-junction study has revealed conductance of the organometallic molecular wires with the thioacetylene backbones higher than that of the related organometallic wires having arylethynylruthenium linkages with the sulfur anchor groups, trans-{p-MeS−C6H4-(C≡C)n}2Ru(phosphine)4 4 n (n=1, 2) and trans-(Th−C≡C)2Ru(phosphine)4 5 (Th=3-thienyl). It should be noted that the molecular junctions constructed from the butadiynyl wire 2R , trans-{ Au −RS−(C≡C)2}2Ru(dppe)2 ( Au : gold metal electrode), show conductance comparable to that of the covalently linked polyynyl wire with the similar molecular length, trans-{ Au −(C≡C)3}2Ru(dppe)2 63 . The DFT non-equilibrium Green's function (NEGF) study supports the highly conducting nature of the thioacetylene molecular wires through HOMO orbitals. 相似文献
50.