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991.
The electrohydrodynamic (EHD) jet is becoming increasingly popular within industrial printing areas based on phenomena induced by electrical potentials. Regardless of the physical observations of unstable ejection phenomena in regions possessing high electric potential, quantitative visualization is still necessary; no report exists exemplifying quantitative visualization. Thus, the size, shape and position of EHD droplets were reconstructed in this study using developed three-dimensional tomography methods. Two computer-synthesized phantoms for the liquid meniscus containing small satellite droplets were generated according to actual images captured by two high-speed cameras. These droplets were made in order to numerically reconstruct droplet behavior. Four three-dimensional tomography methods, such as the algebraic reconstruction technique (ART), the adaptive algebraic reconstruction technique (AART), the simultaneous iterative reconstruction technique (SIRT) and the multiplicative algebraic reconstruction technique (MART), were developed to accurately mimic droplet movement using multiple image views. Four basis functions including the cubic B-spline, cosine, o-Moms and Keys basis functions were adopted in order to improve the performance of the tomographic reconstructions. After completing a comparison of the four tomography results, the MART method in association with the cubic cosine basis function was selected as the means to significantly improve reconstruction accuracy. Additionally, it was the applied method for the reconstruction of the droplet behavior from experimental projections by two cameras. 相似文献
992.
993.
Jiwon Seo 《Tetrahedron letters》2006,47(24):4069-4073
The syntheses of arginine-containing hydroxamates using various peptide coupling methods are described. Fmoc-Arg(NO2)-Cl prepared at low temperature did not undergo intramolecular δ-lactam formation and effectively provided desired hydroxamates (8 and 10) in good yields. Fmoc and N-nitro protecting groups can be easily removed. Therefore, this report provides a facile synthesis of arginine-containing peptidomimetic compounds. 相似文献
994.
In this note we show the sharp L p ?CL q boundedness of multiplier operators of Bochner?CRiesz type having negative indices of which singularity is located in degenerate curve in ${\mathbb{R}^2}$ . L p ?CL q boundedness of their maximal operators is also obtained. 相似文献
995.
Han Sup Lee So Ra Yoo Seung Won Seo 《Journal of Polymer Science.Polymer Physics》1999,37(22):3233-3245
Deformation behavior of the segmented block copolymers was studied with synchrotron small-angle X-ray scattering (SAXS) and Fourier transform infrared spectroscopy (FTIR) methods. Polyurethanes used in this work consist of 4,4′-methylene-bis(phenyl isocyanate) and butanediol as a hard segment, and poly(tetramethylene oxide) of various molecular weights as a soft segment. As expected, the deformation of the domain structure that is macroscopically isotropic before the drawing was anisotropic. Depending on the initial orientation of the hard domains, the deformation behavior was observed to be characteristically different. Whereas the hard domains oriented along the deformation direction underwent the extension of the domain separation distance at the low draw ratio, the perpendicular ones showed the shear compression. Further drawing was found to cause the breakup of the hard domains, followed by the formation of fibril structure oriented along the deformation direction. Based on SAXS and FTIR results, a model is proposed to explain the deformation behavior of the various domains and segments of the segmented block copolymers. By quantitatively analyzing the conformation of the soft segment during the deformation process, the model proposed has been consolidated. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 3233–3245, 1999 相似文献
996.
We report for the first time the syntheses of electron-precise/deficient alloys, Ln5-xCaxGe4 (Ln = La, Ce; x = 3.37, 3.66, 3.82 for La; x = 3.00, 3.20, 3.26 for Ce), in the metal-rich R5Tt4 Zintl system (R = rare earth metal; Tt = Si, Ge). The new alloys extend the phase width from electron-rich to open-shell electron-deficient region in the metal-rich Zintl system and demonstrate possible occurrence of varied electron deficiencies in Zintl phases without structural changes, as a result of other existing structure-forming factors. 相似文献
997.
Tae Bum Lee Kyoung Tai No Sun Hang Cho Seung Su Kim Jung Ki Seo Jin Ho Lee Soon Hong Yuk 《Journal of Polymer Science.Polymer Physics》2001,39(5):594-600
A nanosphere was formed from a temperature‐responsive random copolymer of (N,N‐dimethylamino)ethyl methacrylate (DMAEMA) and ethyl acrylamide (EAAm) without a crosslinker. When the copolymerization was performed in a water/ethanol solvent mixture (90/10 v/v %) above the lower critical‐solution temperature of poly(DMAEMA‐co‐EAAm), the nanosphere was formed with the propagation of copolymerization. Atomic force microscopy analysis and dynamic light scattering both showed the formation of nanosphere and the size was decreased as the EAAm content increased in the copolymer. To illuminate this nanosphere formation phenomena, molecular dynamic simulations were performed with model polymer solutions. According to the analysis of the simulation trajectory, the ethyl groups of ethanol bind to the hydrophobic sites of poly(DMAEMA) or poly(DMAEMA‐co‐EAAm), and water molecules can bind preferentially to CO groups that are abundant on the surface of the core, which is composed of oligomer and ethanol. This may enable the polymerization to proceed within the core, which is transformed into nanosphere. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 594–600, 2001 相似文献
998.
The linear and polycatenar type 1H-imidazole amphiphiles showing a strong self-assembly tendency to build various supramolecular structures in bulk were synthesized by the esterification reaction of 4′-alkyloxy phenols (for 1-4) and hydroxyphenyl trialkyloxybenzoates (for 5-7) with 4-chlorocarbonyl imidazole. The linear 1H-imidazole amphiphiles formed thermotropic smectic phases, but compound 4 with an ethyl group instead of hydrogen on 1N did not show a mesophase. The polycatenar type 1H-imidazole amphiphiles (5-7) formed thermotropic hexagonal columnar and cubic phases. A phase transition was observed from a columnar phase to a cubic phase as the temperature increased on heating, and vice versa on cooling. In the POM study for compounds 5-7, optically isotropic phases first appeared on cooling from the isotropic melts, and then birefringent mesophases with a nonspecific texture appeared on further cooling. The X-ray analysis shows that the optically isotropic phases were very likely micellar cubic phases with Pm3n symmetry. The birefringent phases were confirmed as hexagonal columnar phases. 相似文献
999.
Hyoung‐Ryun Park Seo‐Eun Im Jung‐Ja Seo Bong‐Gon Kim Jin Ah Yoon Ki‐Min Bark 《Photochemistry and photobiology》2015,91(2):280-290
The specific fluorescence properties of morin (3,2′,4′,5,7‐pentahydroxyflavone) were studied in various CH3OH–H2O and CH3CN–H2O mixed solvents. Although the dihedral angle is large in the S0 state, morin has an almost planar molecular structure in the S1 state owing to the very low rotational energy barrier around the interring bond between B and the A, C ring. The excited state intramolecular proton transfer (ESIPT) at the S1 state cannot occur immediately after excitation, S1 → S0 fluorescence can be observed. Two conformers, Morin A and B have been known. At the CH3OH–H2O, Morin B will be the principal species but at the CH3CN–H2O, Morin A is the principal species. At the CH3OH–H2O, owing to the large Franck–Condon (FC) factor for S2 → S1 internal convernal (IC) and flexible molecular structure, only S1 → S0 fluorescence was exhibited. At the CH3CN–H2O, as the FC factor for S2 → S1 IC is small and molecular structure is rigid, S2 → S0 and S1 → S0 dual fluorescence was observed. This abnormal fluorescence property was further supported by the small pK1 value, effective delocalization of the lone pair electrons of C(2′)–OH to the A, C ring, and a theoretical calculation. 相似文献
1000.
Cavitand-based anion receptors were developed by the introduction of four phenylurea moieties on the upper rim of a resorcin[4]arene. Their binding properties for various anions were investigated in DMSO-d6 using 1H NMR spectroscopic methods, and the high 1:1 binding affinity for carboxylates was observed due to hydrophobic as well as charge-dipole interactions between host and guest. 相似文献