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111.
Maria Mernea Roxana tefania Ulreanu Dana Cucu Jasim Hafedh Al-Saedi Cristian-Emilian Pop Sergiu Fendrihan Giorgiana Diana Carmen Anghelescu Dan Florin Mihilescu 《Molecules (Basel, Switzerland)》2022,27(10)
THz spectroscopy is important for the study of ion channels because it directly addresses the low frequency collective motions relevant for their function. Here we used THz spectroscopy to investigate the inhibition of the epithelial sodium channel (ENaC) by its specific blocker, amiloride. Experiments were performed on A6 cells’ suspensions, which are cells overexpressing ENaC derived from Xenopus laevis kidney. THz spectra were investigated with or without amiloride. When ENaC was inhibited by amiloride, a substantial increase in THz absorption was noticed. Molecular modeling methods were used to explain the observed spectroscopic differences. THz spectra were simulated using the structural models of ENaC and ENaC—amiloride complexes built here. The agreement between the experiment and the simulations allowed us to validate the structural models and to describe the amiloride dynamics inside the channel pore. The amiloride binding site validated using THz spectroscopy agrees with previous mutagenesis studies. Altogether, our results show that THz spectroscopy can be successfully used to discriminate between native and inhibited ENaC channels and to characterize the dynamics of channels in the presence of their specific antagonist. 相似文献
112.
The synthesis of a fluoroalkylated 1,1-dimethoxy-3-iminoisoindoline acetal, the first representative of the halogenated 3-imino-amino-1-acetal class is reported. In contrast to the protio compound, fluoroalkyl groups make the presence of a base unnecessary for its synthesis while stabilizing the amino tautomer as revealed by an X-ray structural analysis - the first atomic-level structural characterization of the 1,1-alkoxy-3-amino(imino) isoindoline scaffold. Dimers present in solid-state are H-bonded and define a motif similar to the stabilizing, reverse wobble one encountered in adenine-cytosine pairs of tRNA. The fluoro acetal forms easily both metallo- and metal-free phthalocyanines, supporting the proposal that acetals might be phthalocyanine intermediates. 相似文献
113.
Davenport—Schinzel sequences are sequences that do not contain forbidden subsequences of alternating symbols. They arise in
the computation of the envelope of a set of functions. We show that the maximal length of a Davenport—Schinzel sequence composed
ofn symbols is Θ (nα(n)), where α(n) is the functional inverse of Ackermann’s function, and is thus very slowly increasing to infinity. This is achieved by establishing
an equivalence between such sequences and generalized path compression schemes on rooted trees, and then by analyzing these
schemes.
Work on this paper by the second author has been supported in part by a grant from the U.S.-Israeli Binational Science Foundation. 相似文献
114.
1,2-dideuterio-cyclohexene, 1,2-dideuterio-cyclooctene, and trans-3,4-dideuterio-hex-3-ene were reacted with three >NO* radicals: 4-hydroxyTempo, di-tert-butyliminoxyl, both used as the actual radicals, and phthalimide-N-oxyl (PINO) generated from N-hydroxyphthalimide (NHPI) by its reaction with tert-alkoxyl radicals (t-RO*) and with lead tetraacetate. In all cases, except the NHPI/Pb(OAc)4 system, only mono >NO-substituted alkenes were produced. The 2H NMR spectra imply that 88-92% of monoadducts were formed by the initial abstraction of an allylic H-atom, followed by capture of the allylic radical by a second >NO*, while the remaining 12-8% appear to be formed by an initial addition of >NO* to the double bond followed by H-atom abstraction by a second >NO*. A substantial and sometimes the major product formed with the NHPI/Pb(OAc)4 system has two PINO moieties added across the double bond. Since such diadducts are not formed with the NHPI/t-RO* system, a heterolytic mechanism is proposed, analogous to that known for the Pb(OAc)4-induced acetoxylation of alkenes. A detailed analysis of the NHPI/Pb(OAc)4/alkene products indicates that monosubstitution occurs by both homolytic and heterolytic processes. 相似文献
115.
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117.
Sergiu Aizicovici 《Israel Journal of Mathematics》1980,36(3-4):273-284
The Volterra integrodifferential equation $$\begin{array}{*{20}c} {u_t (t,x) + \smallint '_0 a(t - s)( - \Delta u(s,x) + f(x,u(s,x)))ds = h(t,x),,} \\ {t > 0,x \in \Omega \subset R^N ,} \\ \end{array} $$ together with boundary and initial conditions is considered. The existence of global solutions (in time) is established under weak assumptions onf. An application in heat flow is also indicated. 相似文献
118.
119.
Costes JP Shova S Juan JM Suet N 《Dalton transactions (Cambridge, England : 2003)》2005,(17):2830-2832
A cyclic tetranuclear [V(IV)O-Gd(III)](2) complex with VO and Gd ions alternately arrayed, behaves, from the magnetic point of view, as two independent dinuclear entities each having a S= 4 ground state, as a consequence of an active and ferromagnetic VO-Gd interaction through the double phenoxo bridge and a magnetically inactive VO-Gd interaction through the amide bridge. 相似文献
120.
The authors generalize the classical interpolation formula for Boolean functions of n variables. A characterization of all interpolating systems with 2n elements is obtained. The methods of proof used are intimately related to the solution of linear Boolean equations. 相似文献