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81.
Ossipov D Pradeepkumar PI Holmer M Chattopadhyaya J 《Journal of the American Chemical Society》2001,123(15):3551-3562
To explore the binding properties of [Ru(phen)(2)dppz](2+) complex (phen = 1,10-phenanthroline, dppz = dipyrido[3,2-a:2',3'-c]phenazine) in a sequence-specific manner in DNA duplex, it was tethered through the dppz ligand to a central position as well as both at the 3'- and 5'-ends of oligodeoxyribonucleotide (ODN). The middle [Ru(phen)(2)dppz](2+)-ODN tethered was resolved and isolated as four pure diastereomers, while the 3'- or 5'-[Ru(phen)(2)dppz](2+)-ODNs were inseparable on RP-HPLC. Thermal stability of the (Ru(2+)-ODN).DNA duplexes is found to increase considerably (DeltaT(m) = 12.8-23.4 degrees C), depending upon the site of the covalent attachment of the tethered [Ru(phen)(2)dppz](2+) complex, or the chirality of the [Ru(phen)(2)dppz](2+)-linker tethered at the middle of the ODN, compared to the unlabeled counterpart. Gross differences in CD between the [Ru(phen)(2)dppz](2+)-tethered and the native DNA duplexes showed that the global duplex conformation of the former has considerably altered from the B-type, but is still recognized by DNase I. The thermal melting studies, CD measurements, as well as DNase I digestion data, are interpreted as a result of intercalation of the dppz moiety, which is realized by threading of the Ru(phen)(2) complex part through the DNA duplex core. DNase I footprinting with four diastereomerically pure middle ([Ru(phen)(2)dppz](2+)-ODN).DNA duplexes furthermore showed that the tethered [Ru(phen)(2)dppz](2+)-linker chirality dictates the stereochemical accessibility of various phosphodiester moieties (around the intercalation site) toward the cleavage reaction by the enzyme. The diastereomerically pure ruthenium-modified duplexes, with the well-defined pi-stack, will be useful to explore stereochemistry-dependent energy- and electron-transfer chemistry to understand oxidative damage to the DNA double helix as well as the long-range energy- and electron-transfer processes with DNA as a reactant. 相似文献
82.
Malte Fischer Manfred Manßen Marc Schmidtmann Thorsten Klüner Rüdiger Beckhaus 《Chemical science》2021,12(41):13711
The reaction of the titanium imido complex 1b with 2-butyne leads to the formation of the titanium azadiene complex 2a at ambient temperature instead of yielding the archetypical [2 + 2] cycloaddition product (titanaazacyclobutene) which is usually obtained by combining titanium imido complexes and internal alkynes. The formation of 2a is presumably caused by an initial propargylic C(sp3)–H activation step and quantum chemical calculations suggest that the outcome of this unexpected reactivity is thermodynamically favored. The previously reported titanaazacyclobutene I (which is obtained by reacting 1b with 1-phenyl-1-propyne) undergoes a rearrangement reaction at elevated temperature to give the corresponding five-membered titanium azadiene complex 2b.An unexpected reactivity between a titanium imido complex and internal alkynes was unveiled yielding titanaazacyclobutenes instead of the expected [2 + 2] cycloaddition products. 相似文献
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Justin Holmer Jeremy Marzuola Maciej Zworski 《Communications in Mathematical Physics》2007,274(1):187-216
We study the Gross-Pitaevskii equation with a repulsive delta function potential. We show that a high velocity incoming soliton
is split into a transmitted component and a reflected component. The transmitted mass (L
2 norm squared) is shown to be in good agreement with the quantum transmission rate of the delta function potential. We further
show that the transmitted and reflected components resolve into solitons plus dispersive radiation, and quantify the mass
and phase of these solitons. 相似文献
85.
Ohne Zusammenfassung 相似文献
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Ole Mallow Monther A. Khanfar Moritz Malischewski Pamela Finke Malte Hesse Enno Lork Timo Augenstein Frank Breher Jeffrey R. Harmer Nadezhda V. Vasilieva Andrey Zibarev Artem S. Bogomyakov Konrad Seppelt Jens Beckmann 《Chemical science》2015,6(1):497-504
One-electron oxidation of two series of diaryldichalcogenides (C6F5E)2 (13a–c) and (2,6-Mes2C6H3E)2 (16a–c) was studied (E = S, Se, Te). The reaction of 13a and 13b with AsF5 and SbF5 gave rise to the formation of thermally unstable radical cations [(C6F5S)2]˙+ (14a) and [(C6F5Se)2]˙+ (14b) that were isolated as [Sb2F11]– and [As2F11]– salts, respectively. The reaction of 13c with AsF5 afforded only the product of a Te–C bond cleavage, namely the previously known dication [Te4]2+ that was isolated as [AsF6]– salt. The reaction of (2,6-Mes2C6H3E)2 (16a–c) with [NO][SbF6] provided the corresponding radical cations [(2,6-Mes2C6H3E)2]˙+ (17a–c; E = S, Se, Te) in the form of thermally stable [SbF6]– salts in nearly quantitative yields. The electronic and structural properties of these radical cations were probed by X-ray diffraction analysis, EPR spectroscopy, and density functional theory calculations and other methods. 相似文献