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531.
532.
Yeong‐Tarng Shieh Mao‐Song Lee Show‐An Chen 《Journal of Polymer Science.Polymer Physics》2002,40(7):638-648
Compatibility of crystalline/crystalline polypropylene (PP)/poly(butene‐1) (PB‐1) blends was investigated via the method of equilibrium melting temperature depression followed by determining the polymer–polymer interaction parameter (χ) using the Nishi–Wang equation. The composition variation of the equilibrium melting temperatures of blends (T) was determined with the Hoffman–Weeks plot. The T and its variation with the blend composition depended on the crystallization temperature range. The morphological effect of the blend composition was not a contribution factor for the T depressions of PP and PB‐1 in the blends. The interplay of the dilution effect and molecular fractionation effect of the amorphous component on crystallization of the crystalline component in the blends governed the relation of T with the blend composition. The calculated χ values were negative depending on the blend composition. The negative χ values suggested that PP and PB‐1 in the amorphous region were compatible. The composition variation of the χ values was attributed to the molecular fractionation effect during crystallization. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 638–648, 2002; DOI 10.1002/polb.10125 相似文献
533.
酚酞聚醚醚砜(PES-c)同未交联的双酚A二缩水甘油醚(DGEBA)环氧树脂的共混物呈单一的玻璃化转变温度,其相容性主要归因于混合熵的贡献。PES-C同交联的环氧树脂之间的相容性与所用的固化剂有关。以胺类作DGEBA的固化剂时,共混物不发生相分离;以酸酐作固化剂时,共混物发生相分离。 相似文献
534.
Stabilized liposomes with phospholipid polymers and their interactions with blood cells 总被引:3,自引:0,他引:3
Kazuhiko Ishihara Rieko Tsujino Mika Hamada Noriko Toyoda Yasuhiko Iwasaki 《Colloids and surfaces. B, Biointerfaces》2002,25(4):194-333
To stabilize a phospholipid liposome, addition of various water-soluble polymers into a liposomal aqueous suspension was investigated. The water-soluble polymers were poly(ethylene oxide) (PEO), poly(N-vinyl pyrrolidone) (PVPy) and poly[2-methacryloyloxyethyl phosphorylcholine(MPC)], and poly[MPC-co-n-butyl methacrylate(BMA)]. The gel–liquid crystal transition temperature (Tc) of the diparmitoylphosphatidylcholine (DPPC) liposome was not changed by addition of these polymers significantly. However, membrane fluidity of DPPC liposome treated with water-soluble polymers, which was measured with fluorescence probe, depended on the chemical structure of the water-soluble polymers. In the case of PEO and PVPy, the temperature dependence of membrane fluidity was the same as that of the original DPPC liposome, on the other hand, poly(MPC) and poly(MPC-co-BMA) induced a rise in the temperature where an increase in the membrane fluidity was observed. The release of carboxy fluorescein from the DPPC liposome was suppressed by the addition of the MPC polymers. The liposomes in the MPC polymer solution were stable compared with those in water when plasma was added into the suspension. Interactions with stabilized liposome with blood cells such as platelets and erythrocytes were evaluated. Activation of platelets in contact with liposome covered with poly(MPC) or poly(MPC-co-BMA) was less than PEO-stabilized liposome. On the other hand, no hemolysis of erythrocytes was observed when every polymer-treated liposome was added in the suspension of erythrocytes. Based on these results, the MPC polymers could interact with the liposome surface, adsorb on the liposomes and stabilize them, and had no adverse effect to the blood cells even when they were in a physiological environment. 相似文献
535.
Thermal
analysis of thermoplastic elastomers based on recycled polyethylenes and ground
tyre rubber 总被引:2,自引:0,他引:2
O. Grigoryeva A. Fainleib A. Tolstov P. Pissis A. Spanoudaki A. Vatalis C. Delides 《Journal of Thermal Analysis and Calorimetry》2006,86(1):229-233
Thermal stability
and phase structure of thermoplastic elastomers (TPEs) based on post-consumer
materials such as recycled lowor high-density polyethylene and ground tyre
rubber (GTR) were investigated by using TG, DSC and DMTA analysis. Preliminary
reclamation of GTR leads to enhancement of compatibility between polyethylene
matrix and dispersed GTR particles. 相似文献
536.
Jing Luo Qiguan Wang Xianhong Wang Ji Li Xiaojiang Zhao Fosong Wang 《Journal of polymer science. Part A, Polymer chemistry》2007,45(8):1424-1431
Conductive hybrids were prepared in a water/ethanol solution via the sol–gel process from an inorganic sol containing carboxyl groups and water‐borne conductive polyaniline (cPANI). The inorganic sol was prepared by the hydrolysis and condensation of methyltriethoxysilane with the condensed product of maleic anhydride and aminopropyltriethoxysilane as a catalyst, for which the carboxyl counterion along the cPANI backbone acted as an electrostatic‐interaction moiety. The existence of this electrostatic interaction could improve the compatibility of the two components and contribute to the homogeneous dispersion of cPANI in the silica phase. The electrostatic‐interaction hybrids displayed a conductivity percolation threshold as low as 1.1 wt % polyaniline in an emeraldine base, showing 2 orders of magnitude higher electrical conductivity than that without electrostatic interactions. The electrostatic‐interaction hybrids also showed good water resistance; the electrical conductivity with a cPANI loading of 16 wt % underwent a slight change after 14 days of soaking in water. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1424–1431, 2007 相似文献
537.
The purpose of the present
work was to study the compatibility of metronidazole with different pharmaceutical
excipients (hydroxypropyl methylcellulose, poly(ethylene oxide), microcrystalline
cellulose, dicalcium phosphate dihydrate, and anhydrous dicalcium phosphate)
using differential scanning calorimetry and diffuse reflectance spectroscopy.
Dicalcium phosphate dihydrate was the only excipient that showed interaction
with metronidazole even before storage. Changes referring to a possible transition
to dihydrate form were observed in the thermal curves of anhydrous dicalcium
phosphate after four weeks of storage. Although dicalcium phosphate dihydrate
can be replaced by the anhydrous form in pharmaceutical formulations, the
observed transition might negatively influence the stability of dosage forms. 相似文献
538.
Rahul Misra Bruce X. Fu Andreas Plagge Sarah E. Morgan 《Journal of Polymer Science.Polymer Physics》2009,47(11):1088-1102
Hybrid organic/inorganic nanocomposites based on polyhedral oligomeric silsesquioxane (POSS) nanostructured chemicals and nylon 6 were prepared via melt mixing. Two structurally and chemically different POSS molecules, a closed cage, nonpolar octaisobutyl POSS (Oib‐POSS) and an open cage, polar trisilanolphenyl POSS (Tsp‐POSS) with differing predicted solubility parameters were evaluated in the nylon matrix. Surface analysis, including quasi‐static and dynamic nanoindentation and nanotribological techniques, revealed exceptional improvements in modulus and hardness along with significant reductions in friction. Additionally, surface wetting characteristics of the nylon were reversed, with POSS incorporation yielding low surface energy, highly hydrophobic surfaces. AFM, TEM/EDAX, spectroscopic techniques and thermomechanical analysis were used to evaluate nanoscale dispersion and bulk properties of the composites. Both POSS molecules exhibit preferential surface segregation behavior in the nylon matrix. Tsp‐POSS, with its higher predicted solubility in nylon, exhibited enhanced dispersion and tribomechanical properties at both nano and bulk scale. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1088–1102, 2009 相似文献
539.
Chih‐Chia Cheng Chih‐Feng Huang Ying‐Chieh Yen Feng‐Chih Chang 《Journal of polymer science. Part A, Polymer chemistry》2008,46(19):6416-6424
This article describes a DNA‐like polymer that exhibits the ability to self‐assemble through hydrogen bonding. We synthesized poly[1‐(4‐vinylbenzyl)thymine] (PVBT) and 9‐hexadecyladenine (A‐C16) through an atom transfer radical polymerization (ATRP) and alkylation, respectively. Biocomplementary PVBT/A‐C16 hierarchical supramolecular complexes formed in dilute DMSO solution through nucleobase recognition, that is, hydrogen bonding interactions between the thymine (T) groups of PVBT and the adenine (A) group of A‐C16; evidence for this molecular recognition was also gained from dynamic light scattering studies. 1H NMR titration studies in CDCl3 showed that T–A complexes formed rapidly on the NMR time scale with high association constants (up to 534 M?1). Moreover, FTIR spectroscopic, differential scanning calorimetry, wide‐angle X‐ray diffraction, and small‐angle X‐ray scattering analyses provided further details into the nature of the self‐assembly of these systems. In the bulk state, these complexes self‐assemble into well‐ordered lamellar structures; the changing d‐spacing distance (ranging from 4.98 to 2.32 nm) at different A‐C16 loadings reveals that the molecular structures of the PVBT/A‐C16 complexes are readily tailored. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6416–6424, 2008 相似文献
540.
Alain Forclaz 《Journal of Elasticity》1999,57(3):281-305
We show that for the two wells SO(3) U and SO(3) V to be rank-one connected, where the 3 × 3 symmetric positive definite U and V have the same eigenvalues, it is necessary and sufficient that det(U − V) = 0, a result that does not hold in higher dimensions. Using this criterion and a result of Gurtin, formulae for the twinning
plane and the shearing vector are obtained, which yield an extremely simple condition for the occurrence of so-called compound
twins. As an illustration, we apply our results to the cubic-to-monoclinic transition.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献