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1.
We give combinatorial proofs that certain families of differences of products of Schur functions are monomial-positive. We
show in addition that such monomial-positivity is to be expected of a large class of generating functions with combinatorial
definitions similar to Schur functions. These generating functions are defined on posets with labelled Hasse diagrams and
include for example generating functions of Stanley's (P,ω)-partitions.
T.L. was supported in part by NSF DMS-0600677. 相似文献
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3.
Svitlana V. Shishkina Irina S. Konovalova Pavlo V. Trostianko Anna O. Geleverya Sergiy M. Kovalenko Natalya D. Bunyatyan 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(6):822-832
The polymorphic study of 3‐(3‐phenyl‐1H‐1,2,4‐triazol‐5‐yl)‐2H‐1‐benzopyran‐2‐one, C17H11N3O2, was performed due to its potential biological activity and revealed three polymorphic modifications in the triclinic space group P, the monoclinic space group P21 and the orthorhombic space group Pbca. These polymorphs have a one‐column layered type of crystal organization. The strongest interactions between the molecules of the studied structures is stacking between π‐systems, while N—H…N and C—H…O hydrogen bonds link stacked columns forming layers as a secondary basic structural motif. C—H…π hydrogen bonds were observed between neighbouring layers and their role is the least significant in the formation of the crystal structure. Packing differences between the polymorphic modifications are minor and can be identified only using an analysis based on a comparison of the pairwise interaction energies. 相似文献
4.
Svitlana V. Shishkina Igor V. Ukrainets Olga V. Vashchenko Natali I. Voloshchuk Pavlo S. Bondarenko Lidiya A. Petrushova Galina Sim 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(1):69-74
The title benzothiazine‐3‐carboxamide, C17H16N2O4S, crystallized in two enantiomorphic crystal forms with the space groups P32 and P31 despite the absence of a classic stereogenic atom. The molecular structures are mirror images of each other. Only one sulfonyl O atom takes part in intramolecular hydrogen bonding as a proton acceptor and this atom is different in the two enantiomorphic structures. As a result, the S atom becomes a pseudo‐stereogenic centre. This fact is worth taking into account due to the different biological activities of the enantiomorphic forms. One form possesses a high analgesic activity, while the other form revealed a high anti‐inflammatory activity. 相似文献
5.
Pavlo Solokha Serena De Negri Bernhard Eck Adriana Saccone 《Journal of solid state chemistry》2010,183(12):2995-3001
The crystal structures of two new ternary phases, La4Ag10Mg3 and La4Ag10.3Mg12, were refined from X-ray single crystal diffraction data. La4Ag10Mg3 crystallizes in the Ca4Au10In3 structure type, an ordered variant of the binary Zr7Ni10 compound: orthorhombic, Cmce, oS68, a=14.173(5), b=10.266(3), c=10.354(3) Å, Z=4, wR2=0.0826, 676 F2 values, 50 variables. La4Ag10.3Mg12 represents a new structure type: orthorhombic, Cmmm, oS116-10.32, a=9.6130(3), b=24.9663(8), c=9.6333(2) Å, Z=4, wR2=0.0403, 1185 F2 values, 101 variables. The structural analysis of both compounds, highlighting a significant contraction of the Ag-Mg distances, suggests the existence of three-dimensional [Ag-Mg] networks hosting La atoms. LMTO calculations applied to La4Ag10Mg3 indicate that the strongest bonds occur for Ag-Ag and Ag-Mg interactions, and confirm the presence of a 3D∞[Ag10Mg3]δ− polyanionic framework balanced by positively charged La atoms. 相似文献
6.
Dr. Pavlo Nikolaienko Marc Jentsch Dr. Ajit P. Kale Dr. Yunfei Cai Prof. Dr. Magnus Rueping 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(29):7177-7184
A hydrogen atom transfer-directed electrochemical intramolecular C−H amination has been developed in which the N-radical species are generated at the anode, and the base required for the reaction is generated at the cathode. A broad range of valuable pyrrolidines were prepared in good yields and with high chemoselectivity. The reaction was easily scaled up in both batch and continuous flow systems. 相似文献
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R. Pánek O. Bilyková V. Fuchs M. Hron P. Chráska P. Pavlo J. Stöckel J. Urban V. Weinzettl J. Zajac F. Žáček 《Czechoslovak Journal of Physics》2006,56(2):B125-B137
The COMPASS-D tokamak, originally operated by UKAEA at Culham, UK, will be reinstalled at the Institute of Plasma Physics (IPP) AS CR. The COMPASS device was designed as a flexible tokamak in the 1980s mainly to explore the MHD physics. Its operation (with D-shaped vessel) began at the Culham Laboratory of the Association EURATOM/ UKAEA in 1992.The COMPASS-D tokamak will have the following unique features after putting in operation on IPP Prague. It will be the smallest tokamak with a clear H-mode and ITER-relevant geometry. ITER-relevant plasma conditions will be achieved by installation of two neutral beam injection systems (2 × 300 kW), enabling co-and counter-injections. Redeployment of the existing LH system (400 kW) is also envisaged. A comprehensive set of diagnostics focused mainly on the edge plasma will be installed.The scientific programme proposed for the COMPASS-D tokamak installed in IPP Prague will benefit from these unique features of COMPASS-D and consist of two main scientific projects, both highly relevant to ITER-Edge plasma physics (H-mode studies) and Wave-plasma interaction studies.The COMPASS-D tokamak will offer an important research potential as a small, flexible and low-cost facility with ITER-relevant geometry. 相似文献
9.
P. Solokha M. Giovannini N.R. Lee-Hone D.H. Ryan 《Journal of solid state chemistry》2011,184(9):2498-2505
The crystal structure of the ternary intermetallic compound Yb3Pd2Sn2 has been determined ab initio from powder X-ray diffraction data. The compound crystallizes as a new structure type in the orthorhombic space group Pbcm and lattice constants a=0.58262(3), b=1.68393(8), c=1.38735(7) nm. Yb3Pd2Sn2 is composed of a complex ∞[Pd2Sn2]δ− polyanionic network in which the Yb ions are embedded. A comparison between this structure and those of Eu3Pd2Sn2 and Ca3Pd2Sn2, other novel polar intermetallic compounds, was made. DC susceptibility and 170Yb Mössbauer spectroscopic measurements indicate a close-to divalent Yb behavior. Moreover, a hybridization between 4f and conduction electrons is suggested by electronic structure calculations and heat capacity measurements. 相似文献
10.