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201.
Direct reductive amination (DRA) using triethylsilane (TESH) and catalytic bismuth(III) chloride (BiCl3) is described for the first time. The use of TESH and BiCl3 provides easy handling, low cost, non-toxicity, and a mild Lewis acid activity, thereby meeting the demand for green and sustainable chemistry. The developed DRA is highly chemoselective and applicable to less-basic amines. The experimental results of this study revealed that the developed DRA could be catalyzed by BiCl3, which was gradually reduced to Bi(0) or bismuth with a low valency by TESH, but TESCl, Bi(0), and Bi(0) with TESCl catalyzed the DRA to some extent. 相似文献
202.
We propose a series of carbon nanostructures in the shape of tetrapod as a kind of three-dimensional junction for carbon nanotubes.
The tetrapod junctions are such open networks that are made of sp2 carbon atoms only, have negative Gaussian curvature, and connect four nanotubes together. We define the structure of standard
tetrapod junctions, the simplest one, that have 12 heptagons other than hexagons and have the Td symmetry.Our tight-binding energy-band calculations for the standard tetrapod junctions of smaller sizes show that their
electronic property mainly depends on one particular topological factor: the junctions having a carbon atom in the center
of each triangular face of tetrahedron exhibit metallic band structure while the junctions having a benzene ring in the center
of the faces are semiconductors. We also find that tetrapod junctions connecting (6,0) nanotubes exhibit a flat band near
the Fermi energy in a particular momentum region. The origin of the flat band states can be figured out from the wavefunction
distribution. We also show the possibility to extend the standard tetrapod junctions to some non-standard ones that can connect
nanotubes of different kinds and/or radii. 相似文献
203.
204.
Hisatoshi Konishi Rie Yokoyama Katsuhiro Hikawa Takehiro Nakada Kazuhiro Kobayashi Osamu Morikawa 《合成通讯》2013,43(5):605-610
Methylene-bridged resorcin[4]arene dimers were synthesized by the Sc(OTf)3-catalyzed hydroxymethylation of partially acetylated resorcin[4]arenes, and their preliminary complexation properties with tetraethylammonium ion were examined in CD3OD by 1H NMR spectroscopy. The dimers adopted a closed capsular conformation in this solvent and bound the guest molecule into their cavity. 相似文献
205.
A. Breakstone R. Campanini H. B. Crawley G. M. Dallavalle M. M. Deninno K. Doroba D. Drijard F. Fabbri A. Firestone H. G. Fischer H. Frehse W. Geist G. Giacomelli R. Gokieli M. Gorbics P. Hanke M. Heiden W. Herr D. Isenhower E. E. Kluge J. W. Lamsa T. Lohse W. T. Meyer G. Mornacchi T. Nakada M. Panter A. Putzer K. Rauschnabel B. Rensch F. Rimondi M. Schmelling G. P. Siroli J. D. Skeens R. Sosnowski M. Szczekowski O. Ullaland D. Wegener R. Yeung Ames Collaboration Bologna Collaboration CERN Collaboration Dortmund Collaboration Heidelberg Collaboration Warsaw Collaboration 《Zeitschrift fur Physik C Particles and Fields》1989,43(3):522-522
Data are presented for the first time on inclusive Pomeron-Pomeron interactions which produce a central systemX (composed mainly of multimeson states) in proton-proton collisions at \(\sqrt s \) at the CERN ISR. The systemX has a Feynman-x distribution which is sharply peaked atx f=0, is inconsistent with any significant contributions from Reggeon exchange processes, and has an invariant mass dependence in good agreement with the predicted formM x ?2 . Kaon production is about 15% of pion production, nearly independent ofM x, while proton-antiproton production averages about 5% of pion production and increases withM x. The structure of the central systemX develops into a jetlike shape, asM x increases, as would be expected from a model of Pomeron fragmentation. The shape of thex f(π) distribution in the center of mass of theX system (although not proving existence) is consistent with asoft partonic substructure of the Pomeron. 相似文献
206.
Title azaannulenes, the paratropic and diatropic vinylogues of pyridine, were synthesized starting from the annulenones. 相似文献
207.
Keiko Nakada Seiya Kondo Yoshiteru Matsumoto Masamichi Yamanaka 《Tetrahedron letters》2017,58(49):4612-4616
Dynamic covalent chemistry is an effective technique for the preparation of complex organic compounds. We succeeded in synthesizing a cage-shaped compound through the aggregation of two types of functional molecules. More specifically, a tris-imine 5 was quantitatively obtained by reacting a C3-symmetric trialdehyde 1 with a triamine 4 in acetonitrile in the presence of a trifluoroacetic acid catalyst. We also achieved the synthesis of the corresponding triamine 9 and the acetylated derivative 10 through reduction of the tris-imine CN double bonds and subsequent acetylation. 相似文献
208.
209.
Intermolecular magnetic interactions through hydrogen bonding of the carboxy group for dimers of allyl, benzyl, and chlorinated benzyl radicals have been investigated as model systems by the ab initio molecular orbital (MO) and density functional theory (DFT) calculations. It is found possible to propagate magnetic interaction through hydrogen bonding, although the effect is small. The spin densities of π- and σ-electrons have shown that antiferromagnetic coupling exists between the two intermolecular oxygen atoms in the ground state. This behavior is consistent with McConnell’s model, being applied to the planar configuration of the two hydrogen-bonded carboxy groups. 相似文献
210.
Tsutsui S. Nakada M. Nasu S. Honma T. Tokiwa Y. Aoki D. Wisniewski P. Haga Y. Ōnuki Y. 《Hyperfine Interactions》2002,141(1-4):237-242
We have determined the distribution of the 5f-quadrupoles and detected the 5f-quadrupole order in the uranium intermetallics, uranium dipnictides and UPd3, with 238U Mössbauer spectroscopy. We have declared that the distribution of the 5f-qaudrupoles depends on the magnetic sequence in uranium dipnictides. The distribution of the 5f-quadrupole is spherical in UBi2, while those are oblate within c-plane in UP2, UAs2 and USb2. We have observed the sudden drop of the recoil-free fraction above the transition temperature of the quadrupole order in UPd3. The present result suggests the change of the phonon states due to the quadrupole order in this compound.
相似文献