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排序方式: 共有153条查询结果,搜索用时 15 毫秒
1.
The preparation of polymer microcapsules of well defined size in the range of 10–50 μm with different shell thickness to
core diameter ratios is described. An aerosol of monodisperse droplets of a homogeneous ternary liquid system which contained
a hydrophobic component and a hydrophilic component dissolved in a high-volatile mutual solvent, was produced by dispersing
with a vibrating-orifice aerosol generator. After the evaporation of the solvent in a nitrogen atmosphere the particles demix
and form a two-phase droplet of core-shell type. These droplets were illuminated with UV light and polymerized to highly monodisperse
microcapsules with a solid polymer shell and a liquid core. The properties of the resulting particles (size, size distribution,
shell thickness, shape and surface characteristics) were investigated by scanning electron microscopy, Raman spectroscopy
on single optically levitated particles, and confocal Raman micro spectroscopy. The microcapsules were highly monodisperse
and have spherical shape.
Received: 24 July 1996 Accepted: 29 August 1996 相似文献
2.
Oğul Esen Anindya Ghose Choudhury Partha Guha Hasan Gümral 《Regular and Chaotic Dynamics》2016,21(2):175-188
Degenerate tri-Hamiltonian structures of the Shivamoggi and generalized Raychaudhuri equations are exhibited. For certain specific values of the parameters, it is shown that hyperchaotic Lü and Qi systems are superintegrable and admit tri-Hamiltonian structures. 相似文献
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Iyad Karamé Esen Bellur Sven Rotzoll Peter Langer Christine Fischer Jens Holz 《合成通讯》2013,43(7):1067-1076
Highly enantioselective hydrogenation of β‐alkyl and β‐(ω‐chloroalkyl) substituted β‐keto esters was achieved with Ru catalysts based on chiral diphosphines in EtOH at 50°C under 50‐bar initial hydrogen pressure, affording the corresponding β‐hydroxy esters in >98% ee. 相似文献
7.
Dr. Cemal Albayrak Gözde Barım Prof. Ömer Dag 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(44):15026-15035
Hydrated CaCl2, LiI, and MgCl2 salts induce self‐assembly in nonionic surfactants (such as C12H25(OCH2CH2)10OH) to form lyotropic liquid‐crystalline (LLC) mesophases that undergo a phase transition to a new type of soft mesocrystal (SMC) under ambient conditions. The SMC samples can be obtained by aging the LLC samples, which were prepared as thin films by spin‐coating, dip‐coating, or drop‐casting of a clear homogenized solution of water, salt, and surfactant over a substrate surface. The LLC mesophase exists up to a salt/surfactant mole ratio of 8, 10, and 4 (corresponding to 59, 68, and 40 wt % salt/surfactant) in the CaCl2, LiI, and MgCl2 mesophases, respectively. The SMC phase can transform back to a LLC mesophase at a higher relative humidity. The phase transformations have been monitored using powder X‐ray diffraction (PXRD), polarized optical microscopy (POM), and FTIR techniques. The LLC mesophases only diffract at small angles, but the SMCs diffract at both small and wide angles. The broad surfactant features in the FTIR spectra of the LLC mesophases become sharp and well resolved upon SMC formation. The unit cell of the mesophases expands upon SMC transformation, in which the expansion is largest in the MgCl2 and smallest in the CaCl2 systems. The POM images of the SMCs display birefringent textures with well‐defined edges, similar to crystals. However, the surface of the crystals is highly patterned, like buckling patterns, which indicates that these crystals are quite soft. This unusual phase behavior could be beneficial in designing new soft materials in the fields of phase‐changing materials and mesostructured materials, and it demonstrates the richness of the phase behavior in the salt–surfactant mesophases. 相似文献
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The free radical copolymerization of (5-bromo-1-Benzofuran-2-yl)(phenyl)-O-methacrylketoxime (BPMKO) with 2-(4-acetylphenoxy)-2-oxoethyl-2-methylacrylate(AOEMA) has been carried out in 1, 4-dioxane at 65°C ± 1 and was analyzed by Fourier transform infrared, 1H-NMR, 13C-NMR and gel permeation chromatography. Elemental analysis was used to determine the molar fractions of BPMKO and AOEMA in the copolymers. The monomer–reactivity ratios were calculated according to the general copolymerization equation using Kelen-Tüdõs and Finemann-Ross linearization methods. The reactivity ratios indicated a tendency toward random copolymerization. The polydispersity indices of the polymers were determined by gel permeation chromatography and suggested a strong tendency for chain termination by disproportionation. The thermal behaviors of copolymers with various compositions were investigated by differential scanning calorimetry and thermogravimetric analysis. The glass-transition temperature of the copolymers increased with increasing BPMKO content in the copolymers. All the products showed moderate activity against different strains of bacteria and fungi. 相似文献