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排序方式: 共有243条查询结果,搜索用时 10 毫秒
191.
Elena V. Sergeeva Ivan A. Shuklov Dmitrii Yu. Antonov Natalia V. Vorontsova Evgenii V. Vorontsov Zoya A. Starikova Michail M. Il’in Valeria I. Rozenberg 《Tetrahedron: Asymmetry》2010,21(8):1004-1010
Three techniques for the resolution of 4-formyl[2.2]paracyclophane were examined with the separation of the diastereomeric derivatives with (R)- and (S)-2-hydrazino-2-oxo-N-(1-phenylethyl)acetamide followed by their hydrolysis being found to be the most efficient, allowing (Rp)- and (Sp)-4-formyl[2.2]paracyclophanes to be obtained with 99.5% and 98.7% ee, respectively. 相似文献
192.
Vereshchagin Anatoly N. Karpenko Kirill A. Elinson Michail N. Goloveshkin Alexander S. Dorofeeva Evgeniya O. Egorov Mikhail P. 《Research on Chemical Intermediates》2020,46(2):1183-1199
Research on Chemical Intermediates - A novel four-component diastereoselective synthesis of polysubstituted 2-piperidinones is reported. The Michael addition–Mannich cascade of... 相似文献
193.
Alexander S. Lyakhov Pavel N. Gaponik Michail M. Degtyarik Ludmila S. Ivashkevich 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(8):m399-m401
In the title molecular complex, [Cu4Cl6O(2‐EtTz)4], where 2‐EtTz is 2‐ethyltetrazole (C3H6N4), the central O atom is located on the symmetry site and is tetrahedrally coordinated to four Cu atoms, with Cu—O distances of 1.8966 (4) Å. A very slight distortion of Cu4O from a regular tetrahedron is observed [two Cu—O—Cu angles are 108.76 (3)° and four others are 109.828 (13)°]. Each Cu atom is connected to three others via the Cl atoms, forming a slightly distorted Cl octahedron around the O atom, with O⋯Cl distances of 2.9265 (7) Å for Cl atoms lying on the twofold axis and 2.9441 (13) Å for those in general positions. The Cu atom has a distorted trigonal–bipyramidal environment, with three Cl atoms in the equatorial plane, and with the N atom of the 2‐ethyltetrazole ligand and the μ4‐O atom in axial positions. The Cu atom is displaced out of the equatorial plane by ca 0.91 Å towards the coordinated N atom of the 2‐ethyltetrazole ligand. 相似文献
194.
Ivanova BB Arnaudov MG 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,65(1):56-61
Stereo structural characterization of methionine-containing tripeptides glycine-glycine-methionine (Gly-Gly-Met) and methionine-glycine-glycine (Met-Gly-Gly) is carried out by means of linear-dichroic infrared spectral analysis of oriented as nematic liquid crystal suspension solid samples. Thus obtained data are compared with theoretical ones received by ab initio calculations (Hartree-Fock level of theory and 6-31G** basis set). An IR-spectral characterization of both tripeptides is included as well. 相似文献
195.
Dr. Yohei Hattori Evripidis Michail Alexander Schmiedel Michael Moos Dr. Marco Holzapfel Dr. Ivo Krummenacher Prof. Holger Braunschweig Ulrich Müller Prof. Jens Pflaum Prof. Christoph Lambert 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(68):15463-15471
Up to three polychlorinated pyridyldiphenylmethyl radicals bridged by a triphenylamine carrying electron withdrawing (CN), neutral (Me), or donating (OMe) groups were synthesized and analogous radicals bridged by tris(2,6-dimethylphenyl)borane were prepared for comparison. All compounds were as stable as common closed-shell organic compounds and showed significant fluorescence upon excitation. Electronic, magnetic, absorption, and emission properties were examined in detail, and experimental results were interpreted using DFT calculations. Oxidation potentials, absorption and emission energies could be tuned depending on the electron density of the bridges. The triphenylamine bridges mediated intramolecular weak antiferromagnetic interactions between the radical spins, and the energy difference between the high spin and low spin states was determined by temperature dependent ESR spectroscopy and DFT calculations. The fluorescent properties of all radicals were examined in detail and revealed no difference for high and low spin states which facilitates application of these dyes in two-photon absorption spectroscopy and OLED devices. 相似文献
196.
197.
Michail N. Elinson Anatolii N. Vereshchagin Nikita O. Stepanov Alexey I. Ilovaisky Alexander Ya. Vorontsov Gennady I. Nikishin 《Tetrahedron》2009,65(31):6057-6601
A new type of chemical cascade reaction was found: the direct formation of cyclopropanes from carbonyl compounds and C-H acid. The action of free halogen or active halogen containing compounds on a mixture of 1 equiv of carbonyl compound and 2 equiv of malononitrile in a basic alcohol solution results in the formation of substituted 1,1,2,2-tetracyanocyclopropanes in 15-80% yield. The latter are well-known precursors for the different bicyclic heterosystems, among them compounds containing a cyclopropane ring and possessing different types of pharmacological activity. Thus, the new, simple and efficient ‘one-pot’ way to substituted tetracyanocyclopropanes in 50-80% yield was found directly from such simple and reasonable starting compounds as aldehydes, or some cyclic ketones, or substituted cyclohexanones and malononitrile. 相似文献
198.
Vasiliki Vakali Michail Papadourakis Nikitas Georgiou Nikoletta Zoupanou Dimitrios A. Diamantis Uro Javornik Paraskevi Papakyriakopoulou Janez Plavec Georgia Valsami Andreas G. Tzakos Demeter Tzeli Zoe Cournia Thomas Mauromoustakos 《Molecules (Basel, Switzerland)》2022,27(17)
Quercetin (QUE) is a well-known natural product that can exert beneficial properties on human health. However, due to its low solubility its bioavailability is limited. In the present study, we examine whether its formulation with two cyclodextrins (CDs) may enhance its pharmacological profile. Comparative interaction studies of quercetin with 2-hydroxyl-propyl-β-cyclodextrin (2HP-β-CD) and 2,6-methylated cyclodextrin (2,6Me-β-CD) were performed using NMR spectroscopy, DFT calculations, and in silico molecular dynamics (MD) simulations. Using T1 relaxation experiments and 2D DOSY it was illustrated that both cyclodextrin vehicles can host quercetin. Quantum mechanical calculations showed the formation of hydrogen bonds between QUE with 2HP-β-CD and 2,6Μe-β-CD. Six hydrogen bonds are formed ranging between 2 to 2.8 Å with 2HP-β-CD and four hydrogen bonds within 2.8 Å with 2,6Μe-β-CD. Calculations of absolute binding free energies show that quercetin binds favorably to both 2,6Me-β-CD and 2HP-β-CD. MM/GBSA results show equally favorable binding of quercetin in the two CDs. Fluorescence spectroscopy shows moderate binding of quercetin in 2HP-β-CD (520 M−1) and 2,6Me-β-CD (770 M−1). Thus, we propose that both formulations (2HP-β-CD:quercetin, 2,6Me-β-CD:quercetin) could be further explored and exploited as small molecule carriers in biological studies. 相似文献
199.
Michail N. Elinson Yuliya E. Ryzhkova Anatoly N. Vereshchagin Fedor V. Ryzhkov Mikhail P. Egorov 《Journal of heterocyclic chemistry》2021,58(7):1484-1495
The new electrocatalytic multicomponent transformation has been found: the electrolysis of arylaldehydes, N,N′-dimethylbarbiturate, and cycloxehane-1,3-diones in alcohols in the presence of sodium bromide as a mediator in an undivided cell results in the formation of substituted unsymmetric spirobarbituric dihydrofurans in 62%–76% yields. The optimized reaction conditions and a mechanistic rationale for this electrocatalytic multicomponent transformation are presented. This new electrocatalytic process is a facile and efficient way to produce substituted unsymmetric spirobarbituric dihydrofurans containing both barbituric and 3,5,6,7-tetrahydro-1-benzofuran-4(2H)-one fragments, which are promising compounds for different biomedical applications, among them are anticonvulsants, anti-AIDS agents, and antiinflammatory remedies. The scaffold approach was employed to find a protein, which may be influenced by the synthesized compounds—human aldose reductase was proposed. It was shown by molecular docking studies that such a scaffold search is beneficial and tetrahydro-2′H,4H-spiro[benzofuran-2,5′-pyrimidines] used in this approach are promising for the development of novel aldose reductase inhibitors. 相似文献
200.
One‐Pot ‘On‐solvent’ Multicomponent Protocol for the Synthesis of Medicinally Relevant 4H‐Pyrano[3,2‐c]quinoline Scaffold 下载免费PDF全文
Anatoly N. Vereshchagin Michail N. Elinson Ruslan F. Nasybullin Fedor V. Ryzhkov Sergey I. Bobrovsky Ivan S. Bushmarinov Mikhail P. Egorov 《Helvetica chimica acta》2015,98(8):1104-1114
‘One‐pot’ AcONa‐catalyzed transformation of salicylaldehydes, malononitrile and 4‐hydroxy‐1‐methylquinolin‐2(1H)‐one in the presence of a minimal quantity of EtOH results in fast (3 min) and efficient formation of unknown 2‐amino‐4‐(2‐hydroxyaryl)‐6‐methyl‐5‐oxo‐5,6‐dihydro‐4H‐pyrano[3,2‐c]quinoline‐3‐carbonitriles in 85–98% yields, which are potential pharmaceutical agents for treating disorders responsive to the induction of apoptosis, antiproliferation, or vascular disruption. This efficient ‘on‐solvent’ approach to the 4H‐pyrano[3,2‐c]quinoline scaffold represents a novel synthetic concept for multicomponent reaction (MCR) strategy and allows to combine the synthetic virtues of conventional MCR with ecological benefits and convenience of facile ‘on‐solvent’ procedure. 相似文献