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191.
We present a new, fully anisotropic, criterion for formation of trapped surfaces in vacuum. More precisely we provide local conditions on null data, concentrated in a neighborhood of a short null geodesic segment (possibly flat in all other directions) whose future development contains a trapped surface. This extends considerably the previous result of Christodoulou (Monographs in Mathematics. European Mathematical Society, Switzerland, 2009) which required instead a uniform condition along all null geodesic generators. To obtain our result we combine Christodoulou’s mechanism for the formation of a trapped surface with a new deformation process which takes place along incoming null hypersurfaces. 相似文献
192.
Valeriu Mereacre Denis Prodius Constantin Turta Sergiu Shova George Filoti Juan Bartolom Rodolphe Clrac Christopher E. Anson Annie K. Powell 《Polyhedron》2009,28(14):3017-3025
The new tetranuclear complexes [Fe3Ln(μ3-O)2(CCl3COO)8(H2O)(THF)3]·THF (Ln = CeIII (1), PrIII (2), NdIII (3)) and [Fe3Ln(μ3-O)2(CCl3COO)8(H2O)(THF)3]·THF·C7H16 (Ln = SmIII (4), EuIII (5), GdIII (6), TbIII (7), DyIII (8), HoIII (9), LuIII (10) and YIII (11)) have been prepared. All compounds were prepared by the reaction between [Fe2BaO(CCl3COO)6(THF)6] and the corresponding LnIII nitrate salt. The crystal structures of 1–4, 8 and 9 have been determined; these isostructural molecules have a non-planar {Fe3Ln(μ3-O)2} “butterfly” core. Magnetic susceptibility measurements show dominant intramolecular antiferromagnetic exchange interactions for all the complexes. 57Fe Mössbauer spectroscopy shows three different environments for the FeIII metal ions, all in their high-spin state S = 5/2 (confirming that no electron transfer from CeIII to FeIII occurs in 1). At the time scale of the Mössbauer spectroscopy (about 10−7 s), evidence of magnetization blocking, i.e. slow relaxation of the magnetization, is observed below 3 K for 7, which was confirmed by ac susceptibility measurements. 相似文献
193.
Valeriu Mereacre Denis Prodius Ayuk M. Ako Sergiu Shova Constantin Turta Klaus Wurst Peter Jaitner Annie K. Powell 《Polyhedron》2009,28(16):3551-3555
The reaction of [Fe3EuO2(O2CCCl3)8(H2O)(THF)3] or [Fe2CaO(O2CCCl3)6(THF)4] and [Fe3O(O2CCMe3)6(H2O)3]NO3 with 1,1′-ferrocenedicarboxylic acid (fcdcH2) yielded penta- and hepta-nuclear [Fe4O2(O2CCCl3)6(fcdc)(THF)2(H2O)2] and [Fe6O2(OH)2(O2CCMe3)10(fcdc)(H2O)2], respectively, which are the first X-ray structurally characterized clusters comprising Fe(III) and the ferrocenedicarboxylic organometallic ligand. Variable-temperature solid-state magnetic susceptibility measurements in the temperature range 1.8–300 K were carried out, and for both complexes a predominantly antiferromagnetic exchange interaction between the metal centres was observed. Mössbauer investigations show the presence of different environments for the Fe(III) atoms and confirm that no electron-transfer from Fe(II) of the ferrocene unit to Fe(III) of the central core occurs. 相似文献
194.
195.
Sergiu I. Vacaru 《Annals of Physics》2001,290(2):9
The kinetic theory is formulated with respect to anholonomic frames of reference on curved spacetimes. By using the concept of nonlinear connection we develop an approach to modelling locally anisotropic kinetic processes and, in corresponding limits, the relativistic nonequilibrium thermodynamics with local anisotropy. This leads to a unified formulation of the kinetic equations on (pseudo) Riemannian spaces and in various higher dimensional models of Kaluza–Klein type and/or generalized Lagrange and Finsler spaces. The transition rate considered for the locally anisotropic transport equations is related to the differential cross section and spacetime parameters of anisotropy. The equations of states for pressure and energy in locally anisotropic thermodynamics are derived. The obtained general expressions for heat conductivity, shear, and volume viscosity coefficients are applied to determine the transport coefficients of cosmic fluids in spacetimes with generic local anisotropy. We emphasize that such local anisotropic structures are induced also in general relativity if we are modelling physical processes with respect to frames with mixed sets of holonomic and anholonomic basis vectors which naturally admits an associated nonlinear connection structure. 相似文献
196.
197.
Sergiu Hart 《International Journal of Game Theory》1973,2(1):53-62
A symmetricn-person game (n, k) (for positive integerk) is defined in its characteristic function form byv(S)=[¦S¦/k], where ¦S¦ is the number of players in the coalitionS and [x] denotes the largest integer not greater thanx, (i.e., anyk players, but not less, can “produce” one unit). It is proved that in any imputation in any symmetric von Neumann-Morgenstern solution of such a game, a blocking coalition ofp=n?k+1 players who receive the largest payoffs is formed, and their payoffs are always equal. Conditions for existence and uniqueness of such symmetric solutions with the otherk?1 payoffs equal too are proved; other cases are discussed thereafter. 相似文献
198.
Sergiu?AizicoviciEmail author Simeon?Reich Alexander?J.?Zaslavski 《Journal of Evolution Equations》2004,4(1):139-156
We examine continuous descent methods for the minimization of
Lipschitzian functions defined on a general Banach space. We establish
several convergence theorems for those methods which are generated by
regular vector fields. Since the complement of the set of regular vector
fields is -porous, we conclude that our results apply to most
vector fields in the sense of Baires categories. 相似文献
199.
Sergiu P. Palii Nikolai I. Raevskii Dmitrii V. Zagorevskii Konstantin M. Indrichan Yurii A. Borisov Nikolai V. Gerbeleu Yurii S. Nekrasov D. V. Zagorevskii Yu. S. Nekrasov O- S. Timofeev A. I. Gren' 《Journal of mass spectrometry : JMS》1991,26(9):742-745
Structures of [ZnNCR]+ and [Zn(NCR)2]+ ions (R = H, Me), which are abundant in the mass spectra of many types of coordination compounds, were studied by the MNDO method. In all cases the most stable isomers correspond to the zinc ion coordinated with the nitrogen(s) of the nitrile ligand. For [Zn(NCR)2]+, the N-Zn-N angles are ~108°. 相似文献
200.
Beatrice-Cristina Ivan Florea Dumitrascu Adriana Iuliana Anghel Robert Viorel Ancuceanu Sergiu Shova Denisa Dumitrescu Constantin Draghici Octavian Tudorel Olaru George Mihai Nitulescu Mihaela Dinu Stefania-Felicia Barbuceanu 《Molecules (Basel, Switzerland)》2021,26(21)
A series of new pyrrole derivatives were designed as chemical analogs of the 1,4-dihydropyridines drugs in order to develop future new calcium channel blockers. The new tri- and tetra-substituted N-arylpyrroles were synthesized by the one-pot reaction of 1-methyl-3-cyanomethyl benzimidazolium bromide with substituted alkynes having at least one electron-withdrawing substituent, in 1,2-epoxybutane, acting both as the solvent and reagent to generate the corresponding benzimidazolium N3-ylide. The structural characterization of the new substituted pyrroles was based on IR, NMR spectroscopy as well as on single crystal X-ray analysis. The toxicity of the new compounds was assessed on the plant cell using Triticum aestivum L. species and on the animal cell using Artemia franciscana Kellogg and Daphnia magna Straus crustaceans. The compounds showed minimal phytotoxicity on Triticum rootlets and virtually no acute toxicity on Artemia nauplii, while on Daphnia magna, it induced moderate to high toxicity, similar to nifedipine. Our research indicates that the newly synthetized pyrrole derivatives are promising molecules with biological activity and low acute toxicity. 相似文献