全文获取类型
收费全文 | 123篇 |
免费 | 3篇 |
专业分类
化学 | 106篇 |
数学 | 6篇 |
物理学 | 14篇 |
出版年
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 8篇 |
2013年 | 10篇 |
2012年 | 14篇 |
2011年 | 8篇 |
2010年 | 4篇 |
2009年 | 8篇 |
2008年 | 8篇 |
2007年 | 5篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2000年 | 2篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1940年 | 1篇 |
排序方式: 共有126条查询结果,搜索用时 15 毫秒
11.
Maria Carolina de CeglieLeonardo Degennaro Aurelia FalcicchioRenzo Luisi 《Tetrahedron》2011,67(48):9382-9388
‘Gear-like’ rotations of simple C-C bonds have been observed in some aziridine methanol derivatives. These restricted rotations have been studied by dynamic and multinuclear magnetic resonance experiments, and the barrier for rotations of Csp3-Csp3 and Csp3-Csp2 bonds have been calculated. The role of an intramolecular hydrogen bond on the stereodynamics has also been demonstrated. 相似文献
12.
13.
Marcotullio MC Pagiotti R Campagna V Maltese F Fardella G Altinier G Tubaro A 《Natural product research》2006,20(10):917-921
In this work the mushroom Sarcodon glaucopus was studied. A new cyathane, glaucopine C (1), was isolated from the hexane extract and identified by 1H and 13C NMR spectra analysis. Glaucopine C showed anti-inflammatory acitvity. 相似文献
14.
Carmen Racles Maria Cazacu Aurelia Ioanid Angelica Vlad 《Macromolecular rapid communications》2008,29(18):1527-1531
The micellization of a polysiloxane‐ketimine has been studied in solvents of different polarity, i.e., dimethylformamide (DMF) and toluene. The critical micelle concentration was determined from surface tension measurements ‐in DMF‐, and from viscosity variation with concentration. Metal complex nanoparticles have been synthesized from this macromolecular ligand in DMF and in toluene, using the formed micelles as templates. Spectroscopic data (IR and UV‐vis) confirmed the metal complexation. TEM observations revealed the formation of nanoparticles with different morphologies, which were consistent with the assumed conformation of the ligand in solutions of the two selective solvents.
15.
Wei Wang Dingfeng Shen Xiao Li Dr. Yuan Yao Prof. Jiaping Lin Aurelia Wang Jiwoo Yu Prof. Zhong Lin Wang Prof. Suck Won Hong Prof. Zhiqun Lin Prof. Shaoliang Lin 《Angewandte Chemie (International ed. in English)》2018,57(8):2139-2143
Shape‐memory polymers (SMPs) are an intriguing class of smart materials possessing reversible shape change and recovery capabilities. Effective routes to shape‐memory porous films (SMPFs) are few and limited in scope owing to the difficulty in manipulating the shape change of pores by conventional methods. Herein we report an unconventional strategy for crafting light‐driven SMPFs by judiciously constructing highly ordered porous films via a facile “breath figure” approach, followed by sequential vapor crosslinking and nondestructive directional light manipulation. Micropores can thus be transformed into other shapes including rectangle, rhombus and size‐reduced micropores at room temperature. The transformed micropores can be reverted to their original shapes by either thermal annealing or UV irradiation. As such, this strategy expands the rich diversity of SMPs accessible. 相似文献
16.
Alajarín M Pastor A Orenes RA Goeta AE Steed JW 《Chemical communications (Cambridge, England)》2008,(34):3992-3994
The self-assembly of chiral tris(m-ureidobenzyl)amines to give dimeric capsules is a highly diastereoselective process in solution, while in the solid state, the formation of the corresponding capsules is not only diastereoselective but also regioselective. 相似文献
17.
Aurelia Pascariu Mircea Mracec Stefan Berger 《International journal of quantum chemistry》2008,108(6):1052-1058
Dynamic NMR spectroscopy at very low temperatures (148–182 K) reveal the dynamic behavior of the (2‐tri(3‐furyl)‐3‐methyl‐4‐cyclopropenyl‐oxaphosphetane) generated during a Wittig reaction between tri(3‐furyl)ethylphosphonium iodine and cyclopropylaldehyde. The possibility of formation of different adducts between Li+ ions and oxaphosphetane or betainic intermediates was checked calculating the formation enthalpies using the MNDO, AM1, and PM3 semiempirical MO methods. The observed species are interpreted as oxaphosphetane complexes with lithium ions present in solution. Quantum mechanical calculations confirm the spectroscopic results. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 相似文献
18.
Alajarín M Cabrera J Pastor A Sanchez-Andrada P Bautista D 《The Journal of organic chemistry》2006,71(14):5328-5339
The reaction of 2-(phenylamino)- and 2-(dimethylamino)thiazoles with dimethyl acetylenedicarboxylate led unexpectedly to dimethyl 6-(phenylamino)- and 6-(dimethylamino)-3,4-pyridinedicarboxylates. Those compounds reasonably result from a sequence of reactions initiated by a [2 + 2] cycloaddition of the alkyne to the formal C=C of the thiazole ring. These pyridines were obtained in nearly all the cases assayed as the exclusive reaction products under rather mild conditions and in fair to good yields. In contrast, the regioisomeric 2-amino-3,4-pyridinedicarboxylates, which would result from a [4 + 2] cycloaddition followed by sulfur extrusion, were only obtained in one particular case. The two reaction paths leading alternatively to both regioisomers were investigated computationally. The respective [2 + 2] and [4 + 2] cycloadducts were found to be formed stepwise from a common dipolar intermediate. Notably, the step following the [2 + 2] cycloaddition (i.e., the ring opening of the fused cyclobutene intermediate to give an all-cis 1,3-thiazepine) was found to take place in a disrotatory mode. Although geometric constraints and electronic factors may reduce the energy for the disrotation, the implication of the fused five-membered ring in the electronic reorganization leading to the 1,3-thiazepine is determinant. In this sense, this step could be regarded also as a thermally allowed six-electron five-center disrotatory electrocyclic ring opening. The proposed mechanism was experimentally supported by the isolation of several intermediates and other experimental facts. 相似文献
19.
Morgan Tizzotti Aurelia Charlot Etienne Fleury Martina Stenzel Julien Bernard 《Macromolecular rapid communications》2010,31(20):1751-1772
This review covers the literature concerning the modification of polysaccharides through controlled radical polymerizations (NMP, ATRP and RAFT). The different routes to well‐defined polysaccharide‐based macromolecules (block and graft copolymers) and graft‐functionalized polysaccharide surfaces as well as the applications of these polysaccharide‐based hybrids are extensively discussed.
20.
Gheorghe Ilia Smaranda Iliescu Adriana Popa Aurelia Visa Bianca Maranescu Vasile Simulescu 《高分子科学杂志,A辑:纯化学与应用化学》2016,53(1):49-54
This paper presents for the first time the synthesis of poly(alkylene-H-phosphonate)s by one-pot tandem reaction of hypophosphorous acid and ethylene glycol. Zirconium oxychloride was used as esterification catalyst, Nickel vinylphosphonate, Nickel sulfate, Nickel chloride hexahydrate were used as transfer hydrogenation catalyst. Nickel vinylphosphonate was synthesized in our laboratory and used for the first time as catalyst in this process. The compounds were characterized by 1H-NMR, 13C-NMR and 31P-NMR spectroscopy. Molar masses were determined by SEC-MALLS technique and depend on the catalyst used. The obtained poly(alkylene-H-phosphonate)s have molar masses between 1.50 and 11.85 kDa, higher than those obtained by other methods mentioned in the literature. 相似文献