全文获取类型
收费全文 | 305篇 |
免费 | 11篇 |
专业分类
化学 | 189篇 |
晶体学 | 3篇 |
力学 | 3篇 |
数学 | 37篇 |
物理学 | 84篇 |
出版年
2021年 | 3篇 |
2020年 | 5篇 |
2017年 | 3篇 |
2016年 | 9篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 14篇 |
2012年 | 14篇 |
2011年 | 10篇 |
2010年 | 7篇 |
2009年 | 7篇 |
2008年 | 15篇 |
2007年 | 12篇 |
2006年 | 6篇 |
2005年 | 9篇 |
2004年 | 11篇 |
2003年 | 4篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1998年 | 4篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 9篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1983年 | 3篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1972年 | 6篇 |
1970年 | 2篇 |
1969年 | 3篇 |
1968年 | 3篇 |
1966年 | 2篇 |
1937年 | 2篇 |
1931年 | 2篇 |
1929年 | 3篇 |
1919年 | 2篇 |
1913年 | 2篇 |
1912年 | 6篇 |
1911年 | 2篇 |
排序方式: 共有316条查询结果,搜索用时 46 毫秒
61.
Knudsen KR Bachmann S Jørgensen KA 《Chemical communications (Cambridge, England)》2003,(20):2602-2603
The half-transamination reaction of alpha-keto esters with pyridoxamine or 4-picolylamine was found to be catalysed by different metal catalysts in organic solvents giving moderate yields and enantioselectivities of up to 37% ee for methyl-3-indole pyruvate. 相似文献
62.
63.
64.
Robert Malmberg Dr. Michael Bachmann Dr. Olivier Blacque Assoc. Prof. Dr. Koushik Venkatesan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(14):3627-3636
Phosphorescent mono-cyclometalated gold(III) complexes and their possible applications in organic light emitting diodes (OLEDs) can be significantly enhanced with their improved thermal stability by suppressing the reductive elimination of the respective ancillary ligands. A rational tuning of the π-conjugation of the cyclometalating ligand in conjunction with the non-conjugated 5,5′-(1-methylethylidene)bis(3-trifluoromethyl)-1H-pyrazole were used as a strategy to achieve room-temperature phosphorescence emission in a new series of gold(III) complexes. Photophysical studies of the newly synthesised and characterised complexes revealed phosphorescent emission of the complexes at room temperature in solution, thin films when doped in poly(methyl methacrylate) (PMMA) as well as in 2-Me-THF at 77 K. The complexes exhibit highly tuneable emission behaviour with photoluminescent quantum efficiencies up to 22 % and excited state lifetimes in the range of 63–300 μs. Detailed photophysical investigations in combination with DFT and TD-DFT calculations support the conclusion that the emission properties are strongly dictated by both the cyclometalating ligand and the ancillary chelating ligand. Thermogravimetric studies further show that the thermal stability of the AuIII complexes has been drastically enhanced, making these complexes more attractive for OLED applications. 相似文献
65.
Ohne Zusammenfassung 相似文献
66.
67.
68.
A synthetic strategy for the construction of chiral salen ligands bearing two rigid xanthene spacers functionalized with carboxylic acid and ester groups is presented. Suzuki cross-coupling methodology is used to furnish the appropriately functionalized xanthene spacers to a salicylaldehyde, which is subsequently condensed with (1R,2R)-(-)-1,2-diaminocyclohexane to produce salen ligands featuring an expandable molecular cleft capable of multiple hydrogen-bonding interactions in addition to metallosalen oxidation chemistry. The ability of these "Hangman" platforms to support multielectron chemistry mediated by proton-coupled electron transfer (PCET) is established by their proclivity to promote the catalytic disproportionation of hydrogen peroxide to oxygen and water via a high-valent metal oxo. Within this functionalized Hangman framework, the stereochemistry of the cyclohexyl backbone of the salen platform is revealed in the epoxidation of 1,2-dihydronaphthalene by the metal oxo. 相似文献
69.
70.
Ohne Zusammenfassung 相似文献