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81.
Prof. Marcus W. Drover Maeve C. Dufour Lindsay A. Lesperance-Nantau Rayni P. Noriega Dr. Kirill Levin Prof. Robert W. Schurko 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(49):11180-11186
Herein, we establish the preparation, characterization, and reactivity of a new diphosphine ligand, 1,2-bis(di(3-dicyclohexylboraneyl)propylphosphino)ethane (P2BCy4), a scaffold that contains four pendant boranes. An entryway into the coordination chemistry of P2BCy4 is established by using nickel, providing the octaboraneyl complex [Ni(P2BCy4)2]—this species contains a boron-rich secondary coordination sphere that reacts readily with Lewis bases. In the case of 4,4′-bipyridine, an air-sensitive coordination polymer is obtained. Characterization of this material by solid-state NMR and EPR spectroscopy reveals the presence of a charge-transfer polymer, which forms as a function of intramolecular Ni→4,4′-bpy electron transfer (ET), providing an array of oxidized nickel sites and reduced 4,4′-bpy radical anion sites. Notably, the related intermolecular reaction between the model fragments [Ni(dnppe)2] (dnppe=1,2-bis(di-n-propylphosphino)ethane) and a bis(boraneyl)-protected 4,4′-bpy, provides no ET. Overall, the P2BCy4 fragment provides a unique opportunity for Lewis base activation, in one case allowing for the facile construction of monomers for incorporation into redox-active macromolecules. 相似文献
82.
A. S. Anshakov E. K. Urbakh V. S. Cherednichenko M. G. Kuzmin A. E. Urbakh 《Thermophysics and Aeromechanics》2015,22(6):775-778
Experimental results on energy characteristics of electric-arc plasma generator for heating technical nitrogen with the power of up to 500 kW are presented. The features of arc discharge glow, thermal efficiency, and service life of the electrodes were determined under the regime of melting the metallurgical raw material in the test plasma electric furnace. 相似文献
83.
A Ferrocenyl Kaleidoscope: Slow Interconversion of Six Diastereo‐atropisomers of 2,6‐Di‐tert‐butyl‐9,10‐diferrocenyltriptycene
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Dr. Kirill Nikitin Dr. Jimmy Muldoon Dr. Helge Müller‐Bunz Prof. Dr. Michael J. McGlinchey 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(12):4664-4670
The title triptycene, 6 , has been isolated as the product of 9,10‐cycloaddition of benzyne to 9,10‐diferrocenyl‐2,6‐di‐tert‐butylanthracene, 5 , whose X‐ray crystal structure is reported. Each ferrocenyl unit in 6 has access to the same three non‐equivalent molecular environments, and their rotations relative to the molecular paddlewheel give rise to six slowly interconverting atropisomers. Their dynamic behaviour in solution is a challenging NMR puzzle that can be successfully solved by taking advantage of the recently described very large diamagnetic anisotropy of the ferrocenyl moiety, together with the C2 symmetry of particular atropisomers. Application of one‐ and two‐dimensional NMR techniques over a range of temperatures together, with a detailed analysis of the homo‐ and heteronuclear correlations in 6 , resulted in unequivocal mapping of the 99 1H and 162 13C positions in the six interconverting systems. Variable‐temperature 2D‐EXSY measurements revealed that, while the stability of the atropisomers is almost identical, they are separated by energy barriers which the ferrocenyls must overcome in the course of their interconversions. The heights of two different rotational barriers have been identified and these experimental findings are in good agreement with DFT calculations. 相似文献
84.
Single‐Atom Gold Catalysis in the Context of Developments in Parahydrogen‐Induced Polarization
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Prof. Avelino Corma Oleg G. Salnikov Danila A. Barskiy Dr. Kirill V. Kovtunov Prof. Igor V. Koptyug 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(19):7012-7015
A highly isolated monoatomic gold catalyst, with single gold atoms dispersed on multiwalled carbon nanotubes (MWCNTs), has been synthesized, characterized, and tested in heterogeneous hydrogenation of 1,3‐butadiene and 1‐butyne with parahydrogen to maximize the polarization level and the contribution of the pairwise hydrogen addition route. The Au/MWCNTs catalyst was found to be active and efficient in pairwise hydrogen addition and the estimated contributions from the pairwise hydrogen addition route are at least an order of magnitude higher than those for supported metal nanoparticle catalysts. Therefore, the use of the highly isolated monoatomic catalysts is very promising for production of hyperpolarized fluids that can be used for the significant enhancement of NMR signals. A mechanism of 1,3‐butadiene hydrogenation with parahydrogen over the highly isolated monoatomic Au/MWCNTs catalyst is also proposed. 相似文献
85.
Mikhail Kamencev Nina Yakimova Leonid Moskvin Irina Kuchumova Kirill Tkach Yulia Malinina Oleg Tungusov 《Electrophoresis》2015,36(24):3014-3017
Separation of 6Li and 7Li isotopes by CZE was demonstrated. The BGE contained 5 mM 4‐aminopyridine, 0.9 mM oxalic acid, 0.25 mM CTAB, and 0.25% w/v Tween 20 (рН = 9.2). The running conditions were +25 kV at 30°C with indirect photometric detection at 261 nm. Under optimal experimental conditions, the analysis time was less than 21 min. Separation of Li preparations with mole fraction of 6Li ranging from 3.44 up to 90.38% was demonstrated. 相似文献
86.
Steven J. Visco Vitaliy Y. Nimon Alexei Petrov Kirill Pridatko Nikolay Goncharenko Eugene Nimon Lutgard De Jonghe Yury M. Volfkovich Daniil A. Bograchev 《Journal of Solid State Electrochemistry》2014,18(5):1443-1456
The extremely high theoretical energy density of the lithium-oxygen couple makes it very attractive for next-generation battery development. However, there are a number of challenging technical hurdles that must be addressed for Li-Air batteries to become a commercial reality. In this article, we demonstrate how the invention of water-stable, solid electrolyte-protected lithium electrodes solves many of these issues and paves the way for the development of aqueous and nonaqueous Li-Air batteries with unprecedented energy densities. We also show data for fully packaged Li-Air cells that achieve more than 800 Wh/kg. 相似文献
87.
Justin Mark Michael P. Hanrahan Dr. Katherine E. Woo Shannon Lee Prof. Dr. Aaron J. Rossini Prof. Dr. Kirill Kovnir 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(25):6392-6401
Lithiation of van der Waals tetrel-arsenides, GeAs and SiAs, has been investigated. Electrochemical lithiation demonstrated large initial capacities of over 950 mAh g−1 accompanied by rapid fading over successive cycling in the voltage range 0.01–2 V. Limiting the voltage range to 0.5–2 V achieved more stable cycling, which was attributed to the intercalation process with lower capacities. Ex situ powder X-ray diffraction confirmed complete amorphization of the samples after lithiation, as well as recrystallization of the binary tetrel-arsenide phases after full delithiation in the voltage range 0.5–2 V. Solid-state synthetic methods produce layered phases, in which Si-As or Ge-As layers are separated by Li cations. The first layered compounds in the corresponding ternary systems were discovered, Li0.9Ge2.9As3.1 and Li3Si7As8, which crystallize in the Pbam (No. 55) and P2/m (No. 10) space groups, respectively. Semiconducting layered GeAs and SiAs accommodate the extra charge from Li cations through structural rearrangement in the Si-As or Ge-As layers and eventually by replacement of the tetrel dumbbells with sets of Li atoms. Ge and Si monoarsenides demonstrated high structural flexibility and a mild ability for reversible lithiation. 相似文献
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