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11.
This paper describes a new convenient and accurate method of calculating x-ray diffraction integrated intensities from detailed cubic bilayer structures. The method is employed to investigate the structure of a particular surfactant system (didodecyldimethylammonium bromide in a solution of oil and heavy water), for which single-crystal experimental data have recently been collected. The diffracted peak intensities correlate well with theoretical structures based on mathematical minimal surfaces. Optimized electron density profiles of the bilayer are presented, providing new insight into key features of the bilayer structure. 相似文献
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Kai Jiang Andriy Zakutayev Jason Stowers Michael D. Anderson Janet Tate David H. McIntyre David C. Johnson Douglas A. Keszler 《Solid State Sciences》2009,11(9):1692-1699
High-quality TiO2 thin films have been deposited from aqueous titanium-peroxo solutions via spin coating. The effects of precursor solution pH on the crystallization behavior, morphology, density, and refractive index of the films are reported. From X-ray diffraction measurements, the amorphous as-deposited films are found to crystallize in the anatase phase at 250 °C. Surface and cross-section SEM images reveal that films deposited from an acidic precursor are more uniform and denser than those deposited from a basic precursor. X-ray reflectivity measurements show that films with smooth surfaces and high densities (up to 87% of single-crystal anatase) can be produced at temperatures as low as 300 °C. Measured densities are consistent with high refractive indices at 633 nm of 2.24 and 2.11 for films derived from acidic and basic precursors, respectively. The uniformity and dense nature of the films have allowed fabrication of multilayer dielectric optical elements with thermal processing at only 300 °C. The distributed Bragg reflector with four bilayers exhibits a reflectance of 92% and a stop band width of 150 nm. The optical microcavity has a quality factor of 20. The optical properties of all elements agree well with theoretical models, indicating good optical quality. Use of the precursor chemistry for direct photopatterning of TiO2 films without a polymer resist is also demonstrated. 相似文献
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Pollack L Tate MW Finnefrock AC Kalidas C Trotter S Darnton NC Lurio L Austin RH Batt CA Gruner SM Mochrie SG 《Physical review letters》2001,86(21):4962-4965
High-intensity, "pink" beam from an undulator was used in conjunction with microfabricated rapid-fluid mixing devices to monitor the early events in protein folding with time resolved small angle x-ray scattering. This Letter describes recent work on the protein bovine beta-lactoglobulin where collapse from an expanded to a compact set of states was directly observed on the millisecond time scale. The role of chain collapse, one of the initial stages of protein folding, is not currently understood. The characterization of transient, compact states is vital in assessing the validity of theories and models of the folding process. 相似文献
17.
Tate J Auguste T Muller HG Salières P Agostini P DiMauro LF 《Physical review letters》2007,98(1):013901
A theoretical investigation is presented that examines the wavelength scaling from near-visible (0.8 micro m) to midinfrared (2 micro m) of the photoelectron distribution and high harmonics generated by a "single" atom in an intense electromagnetic field. The calculations use a numerical solution of the time-dependent Schr?dinger equation (TDSE) in argon and the strong-field approximation in helium. The scaling of electron energies (lambda2), harmonic cutoff (lambda2), and attochirp (lambda -1) agree with classical mechanics, but it is found that, surprisingly, the harmonic yield follows a lambda -(5-6) scaling at constant intensity. In addition, the TDSE results reveal an unexpected contribution from higher-order returns of the rescattering electron wave packet. 相似文献
18.
Daiqiang?Xu Bin?Li Courtney?Tate Kevin?J.?EdgarEmail author 《Cellulose (London, England)》2011,18(2):405-419
The regioselective esterification of cellulose by reaction with bulky acyl halides including pivaloyl chloride, adamantoyl
chloride and 2,4,6-trimethylbenzoyl chloride was studied. Functionalization conditions to achieve a given degree of substitution
(DS) and the resulting ester substitution pattern were described in detail. One- and two-dimensional NMR spectroscopy techniques
were used to confirm the structure of the esters obtained. We compared the effects on substitution of using different esterifying
reagents and solvent systems including DMAc/LiCl, DMSO/TBAF, and ionic liquids (ILs). 相似文献
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This review covers selected surfactant ligands that undergo a change in aggregate morphology upon coordination of a metal ion, with a particular focus on coordination-induced micelle-to-vesicle transitions. The surfactants include microbially produced amphiphilic siderophores, as well as synthetic amphiphilic ligands. The mechanism of the metal-induced phase change is considered in light of the coordination chemistry of the metal ions, the nature of the ligands, and changes in molecular geometry that result from metal coordination. Of particular interest are biologically produced amphiphiles that coordinate transition metal ions and amphiphilic ligands of relevance to bioinorganic chemistry. 相似文献
20.
Naoya Tate Makoto Naruse Yang Liu Tadashi Kawazoe Takashi Yatsui Motoichi Ohtsu 《Applied physics. B, Lasers and optics》2013,112(4):587-592
We have previously demonstrated a novel technique for autonomously forming a nanophotonic droplet, which is micro-scale spherical polymer structure that contains paired heterogeneous nanometric components. The sort-selectivity and alignment accuracy of the nanometric components in each nanophotonic droplet, and the related homogeneity of the optical function, are due to a characteristic pairing process based on a phonon-assisted photo-curing method. The proposed method requires irradiating a mixture of components with light to induce optical near-field interactions between each component, and subsequent processes based on these interactions. The pairing yield of components via the interactions is considered to mainly depend on the frequency of their encounters and the size-resonance effect between encountered components. In this paper, we model these two factors by individual stochastic procedures and construct a numerical model to describe the pairing process. Agreement between the results of numerical and experimental demonstrations shows the validity of our stochastic modeling. 相似文献