全文获取类型
收费全文 | 4214篇 |
免费 | 116篇 |
国内免费 | 7篇 |
专业分类
化学 | 2670篇 |
晶体学 | 34篇 |
力学 | 64篇 |
数学 | 479篇 |
物理学 | 1090篇 |
出版年
2021年 | 29篇 |
2020年 | 39篇 |
2019年 | 41篇 |
2018年 | 27篇 |
2016年 | 62篇 |
2015年 | 70篇 |
2014年 | 81篇 |
2013年 | 154篇 |
2012年 | 145篇 |
2011年 | 174篇 |
2010年 | 114篇 |
2009年 | 90篇 |
2008年 | 150篇 |
2007年 | 138篇 |
2006年 | 149篇 |
2005年 | 144篇 |
2004年 | 133篇 |
2003年 | 131篇 |
2002年 | 76篇 |
2001年 | 83篇 |
2000年 | 84篇 |
1999年 | 30篇 |
1998年 | 27篇 |
1997年 | 44篇 |
1996年 | 84篇 |
1995年 | 57篇 |
1994年 | 79篇 |
1993年 | 60篇 |
1992年 | 61篇 |
1991年 | 57篇 |
1990年 | 56篇 |
1989年 | 47篇 |
1988年 | 49篇 |
1987年 | 63篇 |
1986年 | 57篇 |
1985年 | 58篇 |
1984年 | 62篇 |
1983年 | 46篇 |
1982年 | 52篇 |
1981年 | 58篇 |
1980年 | 42篇 |
1979年 | 48篇 |
1978年 | 54篇 |
1977年 | 55篇 |
1976年 | 56篇 |
1975年 | 53篇 |
1974年 | 56篇 |
1973年 | 41篇 |
1968年 | 28篇 |
1957年 | 30篇 |
排序方式: 共有4337条查询结果,搜索用时 203 毫秒
1.
2.
3.
4.
The electrophoretic mobility change of desferrioxamine B (DFO) was monitored by UV absorption spectrophotometry upon increasing the thorium(IV) concentration in the background electrolyte at two acidities ([HClO4]Tot = 0.0316 and 0.0100 M). These data enabled to assess the speciation model and to determine the equilibrium constant of [Th(DFO)H2]3+ at fixed ionic strength (I = 0.1 M (H,Na)ClO4). Affinity capillary electrophoresis (ACE) turned out to be most helpful in identifying the complexed species by ascertaining its charge and protonation state. The assignment of the correct stoichiometry relied on the reliable estimation of the electrophoretic mobility by assuming similar hydrodynamic radii for (DFO)H4+ and the chelate. The value of the apparent equilibrium constant (log β112 = 38.7 ± 0.4) obtained by ACE compares favorably well with those reported in the literature for thorium and a range of other metal ions, according to a linear free-energy relationship. This method is useful for studying metal-ligand binding equilibria and provides valuable information for further modelling the behavior of tetravalent actinides under environmental conditions. Structural information about the prevalent solution species in acidic conditions was gained by DFT calculations, confirming the bishydroxamato coordination mode of Th4+ by the diprotonated ligand. 相似文献
5.
Analyse von Protease‐Inhibitor‐Interaktionen unter Nutzung evolvierbarer tricyclischer Microviridine
6.
Theo Scholtes Stefan Woetzel Rob IJsselsteijn Volkmar Schultze Hans-Georg Meyer 《Applied physics. B, Lasers and optics》2014,117(1):211-218
The intrinsic relaxation rates of the vector magnetization of cesium vapor enclosed in microfabricated atomic magnetometer cells are investigated. Two methods—the optically detected magnetic resonance and the ground-state Hanle effect—are used to carry out automated measurements in dependence on cell temperature and nitrogen buffer gas pressure. The experimental results are compared with expected contributions of the different relaxation processes and in this way allow the discrimination between them to help further optimization of cell design. The methods are compared in terms of basic features, data quality, and practical applicability. 相似文献
7.
8.
Dmitry Sharapa Prof. Andreas Hirsch Prof. Bernd Meyer Prof. Timothy Clark 《Chemphyschem》2015,16(10):2165-2171
Ab initio and DFT calculations are used to investigate the structure, electronic properties, spectra and reactivity of cubic C8, which is predicted to be aromatic according to Hirsch′s rule. Although highly strained and with a small amount of diradical character, the carbon cube represents a surprisingly deep minimum and should therefore be observable as an isolated molecule. It is, however, predicted to be very reactive, both with itself and triplet oxygen. Calculated IR, Raman, and UV/Vis spectra are provided to aid identification of cubic C8 should it be synthesized. 相似文献
9.
10.
Dr. Xuelin Yao Dr. Heng Zhang Fanmiao Kong Dr. Antoine Hinaut Dr. Rémy Pawlak Prof. Dr. Masanari Okuno Dr. Robert Graf Dr. Peter N. Horton Prof. Dr. Simon J. Coles Prof. Dr. Ernst Meyer Prof. Dr. Lapo Bogani Prof. Dr. Mischa Bonn Prof. Dr. Hai I. Wang Prof. Dr. Klaus Müllen Prof. Dr. Akimitsu Narita 《Angewandte Chemie (International ed. in English)》2023,62(46):e202312610
Structurally defined graphene nanoribbons (GNRs) have emerged as promising candidates for nanoelectronic devices. Low band gap (<1 eV) GNRs are particularly important when considering the Schottky barrier in device performance. Here, we demonstrate the first solution synthesis of 8-AGNRs through a carefully designed arylated polynaphthalene precursor. The efficiency of the oxidative cyclodehydrogenation of the tailor-made polymer precursor into 8-AGNRs was validated by FT-IR, Raman, and UV/Vis-near-infrared (NIR) absorption spectroscopy, and further supported by the synthesis of naphtho[1,2,3,4-ghi]perylene derivatives ( 1 and 2 ) as subunits of 8-AGNR , with a width of 0.86 nm as suggested by the X-ray single crystal analysis. Low-temperature scanning tunneling microscopy (STM) and solid-state NMR analyses provided further structural support for 8-AGNR . The resulting 8-AGNR exhibited a remarkable NIR absorption extending up to ∼2400 nm, corresponding to an optical band gap as low as ∼0.52 eV. Moreover, optical-pump TeraHertz-probe spectroscopy revealed charge-carrier mobility in the dc limit of ∼270 cm2 V−1 s−1 for the 8-AGNR . 相似文献