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41.
N. N. Novikova M. V. Kovalchuk S. N. Yakunin N. D. Stepina A. V. Rogachev E. A. Yurieva I. V. Marchenko T. V. Bukreeva N. N. Kolobylina A. L. Vasiliev 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2017,11(4):685-693
X-ray studies of dipalmitoylphosphatidylcholine (DPPC) single layers on the surface of a liquid provide detailed information on the interaction of metal particles with a single layer upon an increase in the surface pressure up to the collapse. Two complementary X-ray methods are used: grazing incidence diffraction and the X-ray standing waves method. The experimental results obtained for a single layer formed on a colloidal solution of magnetite nanoparticles reveal that the increase in the surface pressure is accompanied by an increase in the concentration of nanoparticles near the surface. In a series of experiments where metal particles of submicron size are sputtered onto a DPPC single layer, a sharp decrease in the intensity of the fluorescence yield from metal atoms is observed while the single layer is compressed. These data suggest that metal particles deposited onto the surface of a single layer were extruded into the aqueous subphase. 相似文献
42.
V. I. Kovalchuk 《Physics of Atomic Nuclei》2009,72(8):1247-1252
A theory of the diffractive scattering of loosely bound three-cluster nuclei by nuclei was developed with allowance for Coulomb interaction. The differential cross sections for the scattering of projectile exotic nuclei 7Be and 8B by 12C nuclei at an energy of 40 MeV per nucleon were calculated within the proposed formalism. The results describe satisfactorily relevant experimental data. 相似文献
43.
Cs. Kotsmar V.S. Alahverdjieva E.V. Aksenenko V.I. Kovalchuk M.E. Leser R. Miller 《Advances in colloid and interface science》2009,150(1):41-54
Depending on the bulk composition, adsorption layers formed from mixed protein/surfactant solutions contain different amounts of protein. Clearly, increasing amounts of surfactant should decrease the amount of adsorbed proteins successively. However, due to the much larger adsorption energy, proteins are rather strongly bound to the interface and via competitive adsorption surfactants cannot easily displace proteins. A thermodynamic theory was developed recently which describes the composition of mixed protein/surfactant adsorption layers. This theory is based on models for the single compounds and allows a prognosis of the resulting mixed layers by using the characteristic parameters of the involved components. This thermodynamic theory serves also as the respective boundary condition for the dynamics of adsorption layers formed from mixed solutions and their dilational rheological behaviour. Based on experimental studies with milk proteins (β-casein and β-lactoglobulin) mixed with non-ionic (decyl and dodecyl dimethyl phosphine oxide) and ionic (sodium dodecyl sulphate and dodecyl trimethyl ammonium bromide) surfactants at the water/air and water/hexane interfaces, the potential of the theoretical tools is demonstrated.The displacement of pre-adsorbed proteins by subsequently added surfactant can be successfully studied by a special experimental technique based on a drop volume exchange. In this way the drop profile analysis can provide tensiometry and dilational rheology data (via drop oscillation experiments) for two adsorption routes — sequential adsorption of the single compounds in addition to the traditional simultaneous adsorption from a mixed solution. Complementary measurements of the surface shear rheology and the adsorption layer thickness via ellipsometry are added in order to support the proposed mechanisms drawn from tensiometry and dilational rheology, i.e. to show that the formation of mixed adsorption layer is based on a modification of the protein molecules via electrostatic (ionic) and/or hydrophobic interactions by the surfactant molecules and a competitive adsorption of the resulting complexes with the free, unbound surfactant. Under certain conditions, the properties of the sequentially formed layers differ from those formed simultaneously, which can be explained by the different locations of complex formation. 相似文献
44.
Yu. A. Dyakova K. B. Ilina P. V. Konarev A. E. Kryukova M. A. Marchenkova A. E. Blagov V. V. Volkov Yu. V. Pisarevsky M. V. Kovalchuk 《Crystallography Reports》2017,62(3):364-369
The structural composition of lysozyme solutions favorable for the formation of the tetragonal form of protein crystals was studied by synchrotron-based small-angle X-ray scattering depending on the protein concentration and the temperature. Along with lysozyme monomers, dimers and octamers are found in crystallization solutions; the octamer content increases with an increase in the protein concentration. 相似文献
45.
V.?V.?Nasedkin N.?M.?Boeva I.?A.?Garbuzova M.?V.?Kovalchuk A.?L.?VasilievEmail author 《Crystallography Reports》2009,54(5):884-900
The structure, chemical composition, and properties of palygorskites from several deposits in the Russian Federation, Ukraine,
Uzbekistan, and Slovakia have been investigated by transmission electron microscopy, microanalysis, X-ray diffraction, IR
spectroscopy, and thermal analysis. It is shown that the palygorskites formed under different physicochemical conditions may
significantly differ in chemical composition, morphology, and defect structure. Depending on the formation conditions, palygorskites
decompose differently upon heating. 相似文献
46.
M. V. Kovalchuk P. A. Prosekov M. A. Marchenkova A. E. Blagov Yu. A. D’yakova E. Yu. Tereshchenko Yu. V. Pisarevskii O. A. Kondratev 《Crystallography Reports》2014,59(5):679-684
The results of an in situ study of the growth of tetragonal lysozyme crystals by high-resolution X-ray diffractometry are considered. The crystals are grown by the sitting-drop method on crystalline silicon substrates of different types: both on smooth substrates and substrates with artificial surface-relief structures using graphoepitaxy. The crystals are grown in a special hermetically closed crystallization cell, which enables one to obtain images with an optical microscope and perform in situ X-ray diffraction studies in the course of crystal growth. Measurements for lysozyme crystals were carried out in different stages of the crystallization process, including crystal nucleation and growth, developed crystals, the degradation of the crystal structure, and complete destruction. 相似文献
47.
Kovalchuk NM Pimienta V Tadmouri R Miller R Vollhardt D 《Langmuir : the ACS journal of surfaces and colloids》2012,28(17):6893-6901
A system far from equilibrium, where the surfactant transfer from a small drop located in the aqueous bulk to the air-water interface results in spontaneous nonlinear oscillations of surface tension, is theoretically and experimentally considered. The oscillations in this system are the result of periodically arising and terminating Marangoni instability. The surfactant under consideration is octanoic acid, the dissociated form of which is much less surface-active than the protonated form. Numerical simulations show how the system behavior can be controlled by changes in pH and ionic strength of the aqueous phase. The results of numerical simulations are in good agreement with experimental data. 相似文献
48.
Alexander Yu. Korchin Vladimir A. Kovalchuk 《The European Physical Journal C - Particles and Fields》2012,72(9):1-11
The fully differential angular distribution for the rare flavor-changing neutral current decay $\bar{B}_{d}^{0} \to\bar{K}^{*0} (\to K^{-} \pi^{+}) \mu^{+}\mu^{-} $ is studied. The emphasis is placed on accurate treatment of the contribution from the processes $\bar{B}_{d}^{0} \to\bar{K}^{*0} (\to K^{-} \pi^{+}) V $ with intermediate vector resonances V=??(770),??(782),?(1020),J/??,??(2S),?? decaying into the ?? + ?? ? pair. The dilepton invariant-mass dependence of the branching ratio, longitudinal polarization fraction f L of the $\bar{K}^{*0}$ meson, and forward?Cbackward asymmetry A FB is calculated and compared with data from Belle, CDF and LHCb. It is shown that inclusion of the resonance contribution may considerably modify the branching ratio, calculated in the SM without resonances, even in the invariant-mass region far from the so-called charmonia cuts applied in the experimental analyses. This conclusion crucially depends on values of the unknown phases of the B 0??K ?0 J/?? and B 0??K ?0 ??(2S) decay amplitudes with zero helicity. 相似文献
49.
Fainerman VB Lylyk SV Aksenenko EV Kovalchuk NM Kovalchuk VI Petkov JT Miller R 《Journal of colloid and interface science》2012,377(1):1-6
The complementary drop and bubble profile analysis and maximum bubble pressure tensiometry are used to measure the dynamic surface tension of aqueous SDS solutions in the presence of hardness salts (CaCl(2) and MgCl(2) in the ratio of 2:1 at concentrations of 6 and 40FH). The presence of hardness salts results in an essential increase of the SDS adsorption activity, which indicates the formation of Ca(DS)(2) and Mg(DS)(2) in the SDS solutions. The surface tension isotherms of SDS in presence of Ca(DS)(2) and Mg(DS)(2) are described using the generalised Frumkin model. The presence of hardness salts accelerates the ageing of SDS solutions as compared with the addition of 0.01 M NaCl due to a faster hydrolysis and hence formation of dodecanol. These results are used to estimate the possible concentration of dodecanol in the studied SDS solutions. The buoyant bubble profile method with harmonic surface oscillations is used to measure the dilational rheology of SDS solutions in presence of hardness salts in the frequency range between 0.005 Hz and 0.2 Hz. The visco-elasticity modulus in the presence of hardness salts is higher as compared with its values in the presence of 0.01 M NaCl additions. The ageing of SDS solutions leads to an essential increase of the visco-elastic modulus. 相似文献
50.
Numerous stacking faults and dislocations (formed by intersection of stacking faults and dislocations limiting nonintersecting stacking faults) in the 3C-SiC films grown by molecular beam epitaxy on a silicon substrate were studied by electron microscopy with the use of weak beams. A procedure for determining any of possible Burgers vectors of the (1/6)〈116〉-type glide dislocations and the (1/6) 〈110〉-and (1/3)〈001〉-type sessile partial dislocations (in face-centered cubic lattices) is developed based on the criterion of the contrast value. The sessile dislocations formed by intersections of stacking faults were shown to have the (1/6)〈110〉-and (1/3)〈001〈-type Burgers vectors. The width of nonintersecting stacking faults corresponds to the stacking-fault energy ranging within 0.1–2 mJ/m2. 相似文献