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1.
Ahlen S Ambrosio M Antolini R Auriemma G Baker R Baldini A Bam BB Barbarino GC Barish BC Battistoni G Bellotti R Bemporad C Bernandini P Bilokon H Bisi V Bloise C Bower C Bussino S Cafagna F Calicchio M Campana D Campana P Carboni M Cecchini S Cei F Chiarella V Cormack R Corona A Coutu S De Cataldo G Dekhissi H De Marzo C De Vincenzi M Di Credico A Diehl E Erriquez O Favuzzi C Ficenec D Forti C Fusco P Giacomelli G Giannini G Giglietto N Giubellino P Grassi M Green P Grillo A Guarino F 《Physical review letters》1994,72(5):608-612
2.
Interactions between a nonionic gemini surfactant and cyclodextrins investigated by small-angle neutron scattering 总被引:2,自引:0,他引:2
Alami E Abrahmsén-Alami S Eastoe J Grillo I Heenan RK 《Journal of colloid and interface science》2002,255(2):403-409
The microstructure of complexes between hydroxypropyl-cyclodextrins (HPCDs) (alpha, beta, and gamma) and a novel gemini surfactant has been investigated by small-angle neutron scattering (SANS). This nonionic hetero-gemini surfactant (denoted NIHG750) contains two hydrophobic groups and two hydrophilic groups. One is a methyl-capped polyoxyethylene chain with 16 oxyethylene units and the other is a secondary hydroxyl group. Various form factor models have been considered for fitting the SANS data. Spherical aggregates (25 to 40 A) with a size slightly larger than that of NIHG750 micelles (about 23 A) appear in mixed systems. These could be micellar aggregates partly covered with a few cyclodextrin molecules. In addition, the results indicate rod formation (r approximately 8 A, L approximately 70 A) for the NIHG-HPCD complexes. This result is consistent with the threading of HPCDs onto NIHG750 to such an extent that the surfactant molecule takes an extended conformation at high levels of HPCD. Also, the results indicate that HPCDs may interact with the oxyethylene groups of the spherical micellar aggregates leading to an increase in micelle size and a gradual transformation to rod-shaped aggregates. The tendency to form rods increases in the order gamma-CD相似文献
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5.
Nettesheim F Grillo I Lindner P Richtering W 《Langmuir : the ACS journal of surfaces and colloids》2004,20(10):3947-3953
We report on the influence of shear on a nonionic lamellar phase of tetraethyleneglycol monododecyl ether (C12E4) in D2O containing clay particles (Laponite RD). The system was studied by means of small-angle light scattering (SALS) and small-angle neutron scattering (SANS) under shear. The SANS experiments were conducted using a H2O/D2O mixture of the respective scattering length density to selectively match the clay scattering. The rheological properties show the familiar shear thickening regime associated with the formation of multilamellar vesicles (MLVs) and a shear thinning regime at higher stresses. The variation of viscosity is less pronounced as commonly observed. In the shear thinning regime, depolarized SALS reveals an unexpectedly strong variation of the MLV size. SANS experiments using the samples with lamellar contrast reveal a change in interlamellar spacing of up to 30% at stresses that lead to MLV formation. This change is much more pronounced than the change observed, when shear suppresses thermal bilayer undulations. Microphase separation occurs, and as a consequence, the lamellar spacing decreases drastically. The coincidence of the change in lamellar spacing and the onset of MLV formation is a strong indication for a morphology-driven microphase separation. 相似文献
6.
Bowker M Morgan C Perkins N Holroyd R Fourre E Grillo F MacDowall A 《The journal of physical chemistry. B》2005,109(6):2377-2386
The interaction of ethene with the Pd(110) surface has been investigated, mainly with a view to understanding the dehydrogenation reactions of the molecule and mainly using a molecular beam reactor. Ethene adsorbs with a high probability over the temperature range 130 to 800 K with the low-coverage sticking probability dropping from 0.8 at 130 K to 0.35 at 800 K. The adsorption is of the precursor type, with a weakly held form of ethene being the intermediate between the gas phase and strong chemisorption. Dehydrogenation begins at approximately 300 K and is fast above 350 K. If adsorption is carried out at temperatures up to approximately 380 K, adsorption saturates after about 0.25 monolayer have adsorbed, but above approximately 450 K, adsorption continues at a high rate with continuous hydrogen evolution and C deposition onto the surface. It appears that, in the intermediate temperature range, the carbonaceous species formed is located in the top layer and thus interferes with adsorption, whereas the C goes subsurface above 450 K, the adsorption is almost unaffected, and the C signal is significantly attenuated in XPS. However, the deposited carbon can easily be removed again by reaction with oxygen, thus implying that the carbon remains in the selvedge, that is, in the immediate subsurface region probably consisting of a few atomic layers. No well-ordered structures are identified in either LEED or STM, though some evidence of a c(2 x 2) structure can be seen. The Pd surface, at least above 450 K, appears to act as a "sponge" for carbon atoms, and this effect is also seen for the adsorption of other hydrocarbons such as acetaldehyde and acetic acid. 相似文献
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Gómez-Graña S Hubert F Testard F Guerrero-Martínez A Grillo I Liz-Marzán LM Spalla O 《Langmuir : the ACS journal of surfaces and colloids》2012,28(2):1453-1459
Gold nanorods in aqueous solution are generally surrounded by surfactants or capping agents. This is crucial for anisotropic growth during synthesis and for their final stability in solution. When CTAB is used, a bilayer has been evidenced from analytical methods even though no direct morphological characterization of the precise thickness and compactness has been reported. The type of surfactant layer is also relevant to understand the marked difference in further self-assembling properties of gold nanorods as experienced using 16-EO(1)-16 gemini surfactant instead of CTAB. To obtain a direct measure of the thickness of the surfactant layer on gold nanorods synthesized by the seeded growth method, we coupled TEM, SAXS, and SANS experiments for the two different cases, CTAB and gemini 16-EO(1)-16. Despite the strong residual signal from micelles in excess, it can be concluded that the thickness is imposed by the chain length of the surfactant and corresponds to a bilayer with partial interdigitation. 相似文献
9.
Summary We conside the possibility of investigating neutrino oscillations in a realistic environment. We discuss theoretical uncertainties
coming from flux calculations, geomagnetic effects and propagation through matter, as well as the capability of identifying
the neutrinoinduced events in real apparata.
Riassunto Si studiano le reali possibilità di esperimenti sotterranei nella ricerca di eventuali oscillazioni di neutrini. Sono discusse le imprecisioni derivanti dal calcolo teorico del flusso aspettato e gli effetti geomagnetici e di propagazione attraverso la materia. Si tiene infine conto della capacità di apparati reali nella identificazione di eventi indotti da neutrini.
Резюме Мы рассматриваем возможность исследования нейтринных осцилляций в реальных подземных экспериментах. Мы обсуждаем теоретические неопределенности, связанные с вычислениями потока, геомагнитными эффектами и распространением через вещество. Также рассматривается возможность идентификации событий, индуцированных нейтрино, с помощью существующей аппаратуры.相似文献
10.
Chen ML Penfold J Thomas RK Smyth TJ Perfumo A Marchant R Banat IM Stevenson P Parry A Tucker I Grillo I 《Langmuir : the ACS journal of surfaces and colloids》2010,26(23):18281-18292
The self-assembly in solution and adsorption at the air-water interface, measured by small-angle neutron scattering, SANS, and neutron reflectivity, NR, of the monorhamnose and dirhamnose rhamnolipids (R1, R2) and their mixtures, are discussed. The production of the deuterium-labeled rhamnolipids (required for the NR studies) from a Pseudomonas aeruginosa culture and their separation into the pure R1 and R2 components is described. At the air-water interface, R1 and R2 exhibit Langmuir-like adsorption isotherms, with saturated area/molecule values of about 60 and 75 ?(2), respectively. In R1/R2 mixtures, there is a strong partitioning of R1 to the surface and R2 competes less favorably because of the steric or packing constraints of the larger R2 dirhamnose headgroup. In dilute solution (<20 mM), R1 and R2 form small globular micelles, L(1), with aggregation numbers of about 50 and 30, respectively. At higher solution concentrations, R1 has a predominantly planar structure, L(α) (unilamellar, ULV, or bilamellar, BLV, vesicles) whereas R2 remains globular, with an aggregation number that increases with increasing surfactant concentration. For R1/R2 mixtures, solutions rich in R2 are predominantly micellar whereas solutions rich in R1 have a more planar structure. At an intermediate composition (60 to 80 mol % R1), there are mixed L(α)/L(1) and L(1)/L(α) regions. However, the higher preferred curvature associated with R2 tends to dominate the mixed R1/R2 microstructure and its associated phase behavior. 相似文献