全文获取类型
收费全文 | 1731篇 |
免费 | 55篇 |
国内免费 | 11篇 |
专业分类
化学 | 1121篇 |
晶体学 | 23篇 |
力学 | 45篇 |
数学 | 313篇 |
物理学 | 295篇 |
出版年
2023年 | 9篇 |
2022年 | 37篇 |
2021年 | 43篇 |
2020年 | 27篇 |
2019年 | 39篇 |
2018年 | 21篇 |
2017年 | 20篇 |
2016年 | 60篇 |
2015年 | 56篇 |
2014年 | 58篇 |
2013年 | 84篇 |
2012年 | 121篇 |
2011年 | 123篇 |
2010年 | 70篇 |
2009年 | 69篇 |
2008年 | 96篇 |
2007年 | 119篇 |
2006年 | 95篇 |
2005年 | 101篇 |
2004年 | 95篇 |
2003年 | 73篇 |
2002年 | 64篇 |
2001年 | 16篇 |
2000年 | 16篇 |
1999年 | 22篇 |
1998年 | 13篇 |
1997年 | 14篇 |
1996年 | 19篇 |
1995年 | 13篇 |
1994年 | 6篇 |
1993年 | 12篇 |
1992年 | 10篇 |
1991年 | 9篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 13篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 11篇 |
1984年 | 8篇 |
1983年 | 16篇 |
1982年 | 13篇 |
1981年 | 13篇 |
1980年 | 11篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1976年 | 3篇 |
1973年 | 4篇 |
1960年 | 5篇 |
1911年 | 2篇 |
排序方式: 共有1797条查询结果,搜索用时 15 毫秒
81.
82.
Dr. Giuseppe Ferrauto Dr. Daniela Delli Castelli Dr. Loredana Leone Prof. Mauro Botta Prof. Silvio Aime Dr. Zsolt Baranyai Prof. Lorenzo Tei 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(16):4184-4193
The new ligand HPDO3MA [(R,R,R,R)-10-(2-hydroxypropyl)-α,α′,α′′-trimethyl-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid] was designed to combine and optimize the chemical properties of the macrocyclic ligands HPDO3A and DOTMA. The presence of the methyl groups on the acetic pendant arms of HPDO3A is expected to rigidify the structure of the ligand and favor an increase of the kinetic inertness of the Ln complexes. 1H NMR spectra of Eu(HPDO3MA) displayed the presence of two pairs of diastereoisomers: SAP (square antiprismatic) and TSAP (twisted square antiprismatic) isomers (56 and 44 %, respectively). In addition, 1H and 17O relaxometric NMR studies of Gd(HPDO3MA) showed approximately a 10 % increase in relaxivity and a faster water exchange rate with respect to Gd(HPDO3A). Moreover, a detailed chemical exchange saturation transfer (CEST) characterization of Yb(HPDO3MA) displayed a sensitivity about two times larger than that of Yb(HPDO3A) both in phantom and in cell labeling experiments. Finally, the kinetic inertness of Yb(HPDO3MA) was measured to be twice as high as that of Yb(HPDO3A), with a dissociation half-life at physiological pH of about 2500 years. 相似文献
83.
84.
Dr. Peter Wick Dr. Anna E. Louw‐Gaume Dr. Melanie Kucki Prof. Harald F. Krug Prof. Kostas Kostarelos Prof. Bengt Fadeel Prof. Kenneth A. Dawson Dr. Anna Salvati Prof. Ester Vázquez Dr. Laura Ballerini Dr. Mauro Tretiach Dr. Fabio Benfenati Dr. Emmanuel Flahaut Dr. Laury Gauthier Prof. Maurizio Prato Dr. Alberto Bianco 《Angewandte Chemie (International ed. in English)》2014,53(30):7714-7718
85.
86.
87.
Abstract The physical properties of Pb2+ impurities in the perovskite-like lattice of KMgF3 are very similar to those of (ns)2 ions in alkali halides. The impurity inhomogeneous distribution leads to high dopant levels in the bottom region of the crystals, with a segregation coefficient equal to 0. 020. The optical features of the 336 nm emission support its attribution to luminescence of Pb2+ ions from the relaxed excited B state. 相似文献
88.
89.
Eva Lucaccini Matteo Briganti Dr. Mauro Perfetti Dr. Laure Vendier Dr. Jean‐Pierre Costes Dr. Federico Totti Prof. Dr. Roberta Sessoli Prof. Dr. Lorenzo Sorace 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(16):5552-5562
The magnetic behaviour of a Dy(LH)3 complex (LH? is the anion of 2‐hydroxy‐N′‐[(E)‐(2‐hydroxy‐3‐methoxyphenyl)methylidene]benzhydrazide) was analysed in depth from both theoretical and experimental points of view. Cantilever torque magnetometry indicated that the complex has Ising‐type anisotropy, and provided two possible directions for the easy axis of anisotropy due to the presence of two magnetically non‐equivalent molecules in the crystal. Ab initio calculations confirmed the strong Ising‐type anisotropy and disentangled the two possible orientations. The computed results obtained by using ab initio calculations were then used to rationalise the composite dynamic behaviour observed for both pure DyIII phase and YIII diluted phase, which showed two different relaxation channels in zero and non‐zero static magnetic fields. In particular, we showed that the relaxation behaviour at the higher temperature range can be correctly reproduced by using a master matrix approach, which suggests that Orbach relaxation is occurring through a second excited doublet. 相似文献
90.
Computational Management Science - In this paper, we consider a random vector $$X=\left( X_1,X_2\right) $$ following a multivariate Skew Normal distribution and we provide an explicit formula for... 相似文献