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51.
Roy Pöllänen Teemu Siiskonen Sakari Ihantola Harri Toivonen Andreas Pelikan Kenneth Inn Jerome La Rosa Balazs Bene 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(3):551-555
High-resolution alpha spectrometry was applied for the activity determination of 10 reference sources containing different
amounts of 238Pu, 239Pu, 240Pu and 242Pu. They were analyzed as blind sources using a novel spectrum analysis tool ADAM. The information needed in the spectrum
unfolding was taken only from the spectrum under investigation, and no tracers were applied. Therefore, a Monte Carlo program
AASI was used to compute geometrical detection efficiency of the measurement setup. All reported activities corresponded to
those of the reference sources within expanded uncertainty. The developed tools can be used for the activity determination
in nondestructive alpha spectrometry or when the radionuclide composition does not change during the sample processing. 相似文献
52.
The local strain range is considered to be the main factor controlling the fatigue damage process. An energetic approach is applied to correlate the elastic-plastic stress and strain near a notch with the remotely applied stress. Fatigue crack initiation lives of LYI2CZ aluminum and 16 Mn steel are predicted from a knowledge of the uniaxial data involving parameters such as the elastic modulus, strain hardening strength and strain hardening exponent. These quantities are contained and identified with the fatigue strength coefficient C* which together with the equivalent stress range provide an estimate for the fatigue life of metals. The results agree well with the test data available in the open literature. 相似文献
53.
Teemu Pennanen 《Mathematics and Financial Economics》2011,5(4):233-248
This paper studies superhedging of contingent claims in illiquid markets where trading costs may depend nonlinearly on the
traded amounts and portfolios may be subject to constraints. We give dual expressions for superhedging costs of financial
contracts where claims and premiums are paid possibly at multiple points in time. Besides classical pricing problems, this
setup covers various swap and insurance contracts where premiums are paid in sequences. Validity of the dual expressions is
proved under new relaxed conditions related to the classical no-arbitrage condition. A new version of the fundamental theorem
of asset pricing is given for unconstrained models with nonlinear trading costs. 相似文献
54.
We introduce a novel generalization of the discrete nonlinear Schr?dinger equation. It supports solitons that we utilize to model chiral polymers in the collapsed phase and, in particular, proteins in their native state. As an example we consider the villin headpiece HP35, an archetypal protein for testing both experimental and theoretical approaches to protein folding. We use its backbone as a template to explicitly construct a two-soliton configuration. Each of the two solitons describe well over 7.000 supersecondary structures of folded proteins in the Protein Data Bank with sub-angstrom accuracy suggesting that these solitons are common in nature. 相似文献
55.
Patrick L. Combettes Teemu Pennanen 《Journal of Mathematical Analysis and Applications》2002,275(2):521-536
The mean iteration scheme originally proposed by Mann is extended to a broad class of relaxed, inexact fixed point algorithms in Hilbert spaces. Weak and strong convergence results are established under general conditions on the underlying averaging process and the type of operators involved. This analysis significantly widens the range of applications of mean iteration methods. Several examples are given. 相似文献
56.
Arellano JB Torkkeli M Tuma R Laurinmäki P Melø TB Ikonen TP Butcher SJ Serimaa RE Psencík J 《Langmuir : the ACS journal of surfaces and colloids》2008,24(5):2035-2041
Chlorosomes are light-harvesting complexes of green photosynthetic bacteria. Chlorosomes contain bacteriochlorophyll (BChl) c, d, or e aggregates that exhibit strong excitonic coupling. The short-range order, which is responsible for the coupling, has been proposed to be augmented by pigment arrangement into undulated lamellar structures with spacing between 2 and 3 nm. Treatment of chlorosomes with hexanol reversibly converts the aggregated chlorosome chlorophylls into a form with spectral properties very similar to that of the monomer. Although this transition has been extensively studied, the structural basis remains unclear due to variability in the obtained morphologies. Here we investigated hexanol-induced structural changes in the lamellar organization of BChl c in chlorosomes from Chlorobium tepidum by a combination of X-ray scattering, electron cryomicroscopy, and optical spectroscopy. At a low hexanol/pigment ratio, the lamellae persisted in the presence of hexanol while the short-range order and exciton interactions between chlorin rings were effectively eliminated, producing a monomer-like absorption. The result suggested that hexanol hydroxyls solvated the chlorin rings while the aliphatic tail partitioned into the hydrophobic part of the lamellar structure. This partitioning extended the chlorosome along its long axis. Further increase of the hexanol/pigment ratio produced round pigment-hexanol droplets, which lost all lamellar order. After hexanol removal the spectral properties were restored. In the samples treated under the high hexanol/pigment ratio, lamellae reassembled in small domains after hexanol removal while the shape and long-range order were irreversibly lost. Thus, all the interactions required for establishing the short-range order by self-assembly are provided by BChl c molecules alone. However, the long-range order and overall shape are imposed by an external structure, e.g., the proteinaceous chlorosome baseplate. 相似文献
57.
The optical transitions of three different size oligo(p-phenylenevinylene)-fullerene dyads (OPV(n)-MPC(60); n = 2-4) and of the corresponding separate molecules are studied using density functional theory (DFT) and time-dependent density functional theory. The DFT is used to determine the geometries and the electronic structures of the ground states. Transition energies and excited-state structures are obtained from the TDDFT calculations. Resonant energy transfer from OPV(n) to MPC(60) is also studied and the Fermi golden rule is used, along with two simple models to describe the electronic coupling to calculate the energy transfer rates. The hybrid-type PBE0 functional is used with a split-valence basis set augmented with a polarization function (SV(P)) in calculations and the calculated results are compared to the corresponding experimental results. The calculated PBE0 spectra of the OPV(n)-MPC(60) dyads correspond to the experimental spectra very well and are approximately sums of the absorption spectra of the separate OPV(n) and MPC(60) molecules. Also, the absorption energies of OPV(n) and MPC(60) and the emission energies of OPV(n) are predicted well with the PBE0 functional. The PBE0 calculated resonant energy transfer rates are in a good agreement with the experimental rates and show the existence of many possible pathways for energy transfer from the first excited singlet states of the OPV(n) molecules to the MPC(60) molecule. 相似文献
58.
Ras RH Ruotsalainen T Laurikainen K Linder MB Ikkala O 《Chemical communications (Cambridge, England)》2007,(13):1366-1368
Long hollow inorganic nanoparticle nanotubes have been synthesized by templating of block copolymer electrospun fibers with clay mineral platelets followed by interlinking of the platelets using condensation reactions. 相似文献
59.
Structure and Bonding in Bis(1‐naphthyl) Diselenide and Bis{[2‐(N,N‐dimethylamino)methyl]phenyl} Tetraselenide,and Their Brominated Derivatives 下载免费PDF全文
Esther M. Takaluoma Teemu T. Takaluoma Raija Oilunkaniemi Risto S. Laitinen 《无机化学与普通化学杂志》2015,641(5):772-779
The formation and crystal structures of bis(1‐naphthyl) diselenide ( 1 ) and bis{[2‐(N,N‐dimethylamino)methyl]phenyl} tetraselenide ( 2 ) are described. Whereas 1 can be produced in good yields, 2 is formed only as a minor product together with the known main product, bis{[2‐(N,N‐dimethylamino)methyl]phenyl} diselenide. The composition of the reaction mixture is semi‐quantitatively estimated by 77Se NMR spectroscopy and DFT calculations. The effect of the n2→σ*(Se–Se) and π→σ*(Se–Se) secondary bonding interactions on the Se–Se bonds is discussed both by DFT calculations and comparison with literature, as available. The bromination of 1 yields monomeric (1‐naphthyl)selenenyl bromide ( 3 ) in good yields. That of the reaction mixture of (C6H4CH2NMe2)Sex (x = 2–4) and Se8 afforded (C6H4CH2NMe2H)2[SeBr4] ( 4 ) and (C6H4CH2NMe2H)2[SeBr6] ( 5 ) in addition to (C6H4CH2NMe2)SeBr, which has been previously reported. 相似文献
60.
B. Twomey A. Nindrayog K. Niemi W. G. Graham D. P. Dowling 《Plasma Chemistry and Plasma Processing》2011,31(1):139-156
The effect of varying process parameters on atmospheric plasma characteristics and properties of nanometre thick siloxane
coatings is investigated in a reel-to-reel deposition process. Varying plasma operation modes were observed with increasing
applied power for helium and helium/oxygen plasmas. The electrical and optical behaviour of the dielectric barrier discharge
were determined from current/voltage, emission spectroscopy and time resolved light emission measurements. As applied power
increased, multiple discharge events occurred, producing a uniform multi-peak pseudoglow discharge, resulting in an increase
in the discharge gas temperature. The effects of different operating modes on coating oxidation and growth rates were examined
by injecting hexamethyldisiloxane liquid precursor into the chamber under varying operating conditions. A quenching effect
on the plasma was observed, causing a decrease in plasma input power and emission intensity. Siloxane coatings deposited in
helium plasmas had a higher organic component and higher growth rates than those deposited in helium/oxygen plasmas. 相似文献