全文获取类型
收费全文 | 1749篇 |
免费 | 47篇 |
国内免费 | 7篇 |
专业分类
化学 | 1385篇 |
晶体学 | 9篇 |
力学 | 18篇 |
数学 | 154篇 |
物理学 | 237篇 |
出版年
2024年 | 1篇 |
2023年 | 9篇 |
2022年 | 42篇 |
2021年 | 101篇 |
2020年 | 40篇 |
2019年 | 60篇 |
2018年 | 74篇 |
2017年 | 49篇 |
2016年 | 70篇 |
2015年 | 76篇 |
2014年 | 58篇 |
2013年 | 163篇 |
2012年 | 82篇 |
2011年 | 107篇 |
2010年 | 92篇 |
2009年 | 76篇 |
2008年 | 106篇 |
2007年 | 120篇 |
2006年 | 82篇 |
2005年 | 88篇 |
2004年 | 56篇 |
2003年 | 63篇 |
2002年 | 47篇 |
2001年 | 15篇 |
2000年 | 11篇 |
1999年 | 23篇 |
1998年 | 13篇 |
1997年 | 17篇 |
1996年 | 23篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 12篇 |
1991年 | 5篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
排序方式: 共有1803条查询结果,搜索用时 109 毫秒
61.
Irina L. Odinets Oleg I. Artyushin Elena V. Sharova Ekaterina V. Matveeva Alexandr N. Turanov Vasilii K. Karandashev 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):146-149
Abstract The extraction properties of a series of carbamoylmethylphosphine oxides and β-aminophosphine oxides with lanthanide metal ions is presented. Tris[bis(2-diphenyl- phosphorylethyl)-aminoethyl]amine is shown to be highly effective for extraction of Re(VII). 相似文献
62.
63.
64.
65.
66.
Xuan Thinh Duong Irina Holmes Ji Li Brett D. Wick Dongyong Yang 《Journal of Functional Analysis》2019,276(4):1007-1060
In this paper we establish the characterization of the weighted BMO via two weight commutators in the settings of the Neumann Laplacian on the upper half space and the reflection Neumann Laplacian on with respect to the weights associated to and respectively. This in turn yields a weak factorization for the corresponding weighted Hardy spaces, where in particular, the weighted class associated to is strictly larger than the Muckenhoupt weighted class and contains non-doubling weights. In our study, we also make contributions to the classical Muckenhoupt–Wheeden weighted Hardy space (BMO space respectively) by showing that it can be characterized via the area function (Carleson measure respectively) involving the semigroup generated by the Laplacian on and that the duality of these weighted Hardy and BMO spaces holds for Muckenhoupt weights with while the previously known related results cover only . We also point out that this two weight commutator theorem might not be true in the setting of general operators L, and in particular we show that it is not true when L is the Dirichlet Laplacian on . 相似文献
67.
Kirill V. Zaitsev Yulia A. Piskun Yuri F. Oprunenko Sergey S. Karlov Galina S. Zaitseva Irina V. Vasilenko Andrei V. Churakov Sergei V. Kostjuk 《Journal of polymer science. Part A, Polymer chemistry》2014,52(9):1237-1250
The aluminum complexes containing two iminophenolate ligands of the type (p‐XC6H4NCHC6H4O‐o)2AlR' (R′=Me ( 3, 4 ) or R′=O(CH2)4OCH=CH2 ( 5, 6 ), X=H ( 3, 5 ), F( 4, 6 )) were synthesized and characterized by 1H, 13C NMR spectroscopy, and X‐ray crystallography. The reaction of AlMe3 with two equivalents of substituted iminophenols gave five‐coordinated {ONR}2AlMe ( 3, 4 ) complexes. Subsequent reaction of these methyl complexes with unsaturated alcohol, HO(CH2)4OCH=CH2, resulted in target compounds 5 and 6 in a good yield. It was shown that the complexes ( 3 ‐ 6 ) are monomeric in solution (NMR) and in solid state (X‐ray analysis). The catalytic activity of the complexes 5 and 6 towards ring‐opening polymerization (ROP) of ?‐caprolactone and d,l ‐lactide was assessed. Complex 5 showed higher activity as compared with 6 , while both of these catalysts induced controlled homo‐ and copolymerization to afford the macromonomers with high content of vinyl ether end groups (Fn > 80%) in a broad range of molecular weights (Mn = 4000–30,000 g mol?1) with relatively narrow MWD (Mw/Mn = 1.1–1.5). © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1237–1250 相似文献
68.
69.
Babushkina Anastasia A. Mikhaylov Vladimir N. Novikov Alexander S. Sorokoumov Viktor N. Gureev Maxim A. Kryukova Mariya A. Shpakov Alexander O. Balova Irina A. 《Chemistry of Heterocyclic Compounds》2022,58(8-9):432-437
Chemistry of Heterocyclic Compounds - The Richter cyclization was used for the synthesis of 6-halo-3-(hydroxymethyl)cinnolin-4(1H)-ones. X-ray analysis revealed that these compounds exist as dimers... 相似文献
70.
Gilian T. Thomas Sofia Donnecke Prof. Irina Paci Prof. J. Scott McIndoe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(54):12359-12362
Zeise's salt, [PtCl3(H2C=CH2)]−, is the oldest known organometallic complex, featuring ethylene strongly bound to a platinum salt. Many derivatives are known, but none involving dinitrogen, and indeed dinitrogen complexes are unknown for both platinum and palladium. Electrospray ionization mass spectrometry of K2[PtCl4] solutions generate strong ions corresponding to [PtCl3(N2)]−, the identity of which was confirmed through ion-mobility spectrometry and MS/MS experiments that proved it to be distinct from its isobaric counterparts [PtCl3(C2H4)]− and [PtCl3(CO)]−. Computational analysis established a gas-phase platinum–dinitrogen bond strength of 116 kJ mol−1, substantially weaker than the ethylene and carbon monoxide analogues but stronger than for polar solvents such as water, methanol and dimethylformamide, and strong enough that the calculated N−N bond length of 1.119 Å represents weakening to a degree typical of isolated dinitrogen complexes. 相似文献