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21.
22.
Let (P) denote the vector maximization problem
where the objective functions f
i
are strictly quasiconcave and continuous on the feasible domain D, which is a closed and convex subset of R
n
. We prove that if the efficient solution set E(P) of (P) is closed, disconnected, and it has finitely many (connected) components, then all the components are unbounded. A similar fact is also valid for the weakly efficient solution set E
w
(P) of (P). Especially, if f
i
(i=1,...,m) are linear fractional functions and D is a polyhedral convex set, then each component of E
w
(P) must be unbounded whenever E
w
(P) is disconnected. From the results and a result of Choo and Atkins [J. Optim. Theory Appl. 36, 203–220 (1982.)] it follows that the number of components in the efficient solution set of a bicriteria linear fractional vector optimization problem cannot exceed the number of unbounded pseudo-faces of D. 相似文献
23.
Classical molecular dynamics simulations of the folding of alanine peptides in aqueous solution are analyzed by constructing a deterministic model of the dynamics, using methods from nonlinear time series analysis. While the dimension of the free energy landscape increases with system size, a Lyapunov analysis shows that the effective dimension of the dynamic system is rather small and even decreases with chain length. The observed reduction of phase space is a nonlinear cooperative effect that is caused by intramolecular hydrogen bonds that stabilize the secondary structure of the peptides. 相似文献
24.
Le Thi Phuong Ngoc Nguyen Anh Triet Alain Pham Ngoc Dinh 《Numerical Functional Analysis & Optimization》2017,38(9):1173-1207
In this paper, we consider a wave equation with integral nonlocal boundary conditions of memory type. First, we establish two local existence theorems by using Faedo–Galerkin method and standard arguments of density. Next, we give a su?cient condition to guarantee the global existence and exponential decay of weak solutions. Finally, we present numerical results. 相似文献
25.
Ta HP Berthelot K Coulary-Salin B Desbat B Géan J Servant L Cullin C Lecomte S 《Langmuir : the ACS journal of surfaces and colloids》2011,27(8):4797-4807
Many in vitro studies have pointed out the interaction between amyloids and membranes, and their potential involvement in amyloid toxicity. In a previous study, we generated a yeast toxic mutant (M8) of the harmless model amyloid protein HET-s((218-289)). In this study, we compared the self-assembling process of the nontoxic wild-type (WT) and toxic (M8) protein at the air-water interface and in interaction with various phospholipid monolayers (DOPE, DOPC, DOPI, DOPS and DOPG). We first demonstrate using ellipsometry measurements and polarization-modulated infrared reflection absorption spectroscopy (PMIRRAS) that the air-water interface promotes and modifies the assembly of WT since an amyloid-like film was instantaneously formed at the interface with an antiparallel β-sheet structuration instead of the parallel β-sheet commonly observed for amyloid fibers generated in solution. The toxic mutant (M8) behaves in a similar manner at the air-water interface or in bulk, with a fast self-assembling and an antiparallel β-sheet organization. The transmission electron microscopy (TEM) images established the fibrillous morphology of the protein films formed at the air-water interface. Second, we demonstrate for the first time that the main driving force between this particular fungus amyloid and membrane interaction is based on electrostatic interactions with negatively charged phospholipids (DOPG, DOPI, DOPS). Interestingly, the toxic mutant (M8) clearly induces perturbations of the negatively charged phospholipid monolayers, leading to a massive surface aggregation, whereas the nontoxic (WT) exhibits a slight effect on the membrane models. This study allows concluding that the toxicity of the M8 mutant could be due to its high propensity to interact with membranes. 相似文献
26.
Le Thi Phuong Ngoc Nguyen Thanh Long 《Nonlinear Analysis: Theory, Methods & Applications》2011,74(18):7111-7125
Motivated by the recent known results about the solvability and existence of asymptotically stable solutions for nonlinear functional integral equations in spaces of functions defined on unbounded intervals with values in the n-dimensional real space, we establish asymptotically stable solutions for a nonlinear functional integral equation in the space of all continuous functions on R+ with values in a general Banach space, via a fixed point theorem of Krasnosel’skii type. In order to illustrate the result obtained here, an example is given. 相似文献
27.
Hydrolysis of the dipeptides glycylserine (GlySer), leucylserine (LeuSer), histidylserine (HisSer), glycylalanine (GlyAla), and serylglycine (SerGly) was examined in oxomolybdate solutions by means of (1)H, (13)C, and (95)Mo NMR spectroscopy. In the presence of a mixture of oxomolybdates, the hydrolysis of the peptide bond in GlySer proceeded under neutral pD conditions (pD = 7.0, 60 °C) with a rate constant of k(obs) = 5.9 × 10(-6) s(-1). NMR spectra did not show evidence of the formation of paramagnetic species, excluding the possibility of Mo(VI) reduction to Mo(V), indicating that the cleavage of the peptide bond is purely hydrolytic. The pD dependence of k(obs) exhibits a bell-shaped profile, with the fastest cleavage observed at pD 7.0. Comparison of the rate profile with the concentration profile of oxomolybdate species implicated monomolybdate MoO(4)(2-) as the kinetically active complex. Kinetics experiments at pD 7.0 using a fixed amount of GlySer and increasing amounts of MoO(4)(2-) allowed for calculation of the catalytic rate constant (k(2) = 9.25 × 10(-6) s(-1)) and the formation constant for the GlySer-MoO(4)(2-) complex (K(f) = 15.25 M(-1)). The origin of the hydrolytic activity of molybdate is most likely a combination of the polarization of amide oxygen in GlySer due to the binding to molybdate, followed by the intramolecular attack of the Ser hydroxyl group. 相似文献
28.
The aim of this work is to investigate the effects of molecular mechanics force fields on amyloid peptide assembly. To this end, we performed extensive replica exchange molecular dynamics (REMD) simulations on the monomer, dimer and trimer of the seven-residue fragment of the Alzheimer's amyloid-β peptide, Aβ(16-22), using the AMBER99, GROMOS96 and OPLS force fields. We compared the force fields by analysing the resulting global and local structures as well as the free energy landscapes at 300 K. We show that AMBER99 strongly favors helical structures for the monomer and does not predict any β-sheet structure for the dimer and trimer. In contrast, the dimer and trimer modeled by GROMOS96 form antiparallel β-sheet structures, while OPLS predicts diverse structures. Overall, the free energy landscapes obtained by three force fields are very different, and we also note a weak structural dependence of our results on temperature. The implications of this computational study on amyloid oligomerization, fibril growth and inhibition are also discussed. 相似文献
29.
Investigations on Metal Catalysts. XXII. Chemisorption of Hydrogen on Pt? Ru and η-Al2O3 Supported Pt? Ru Catalysts Measurements of the H2 chemisorption by volumetric method were carried out on several series of Pt? Ru and η-Al2O3 supported Pt? Ru catalysts. Addition of Ru to Pt and vice versa effects a remarkable influence on the sorption behaviour of the starting samples. For mixtures of carrier-free catalysts and η-Al2O3 as well as Pt? Ru/η-Al2O3 catalysts a hydrogen-spillover effect was found. 相似文献
30.
This work is a continuation of [7]. In that paper, a sufficient condition was given on a real analytic fmlction g defined near 0 in C so that the algebra generated by z2 and g2 is dense in the space of continuous functions on D for all disks D close enough to the origin in C. By using the same methods and some ideas taken from the first named author's thesis we deal with the case where g is only of class C1 near 0. 相似文献