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1.
The effect of pH value on the electrostatic layer-by-layer self-assembly and the photo-responsive behavior of Poly{2-[4-(4-ethoxyphenylazo)phenoxy]ethyl
acrylate-co-acrylic acid} (PEAPE) was studied. Results show that in the studied pH value range, the lower the pH value is, the higher
is the UV-vis absorbance and the larger is the thickness of the multilayer films. FTIR studies indicate that the azo polyelectrolyte
exhibits a different ionization degree in solutions with different pH values. The higher absorbance and the larger thickness
of the layer-by-layer films can be attributed to the low ionization degree and the shrinkage conformation of PEAPE in the
solution with low pH values. FTIR analysis also confirms that the driving force for layer-by-layer self-assembly of PEAPE
and PDAC is the electrostatic interaction.
__________
Translated from Acta Polymerica Sinica, 2007, 5: 440–445 [译自: 高 分子学报] 相似文献
2.
Nicholas W. DeLuca Yossef A. Elabd 《Journal of Polymer Science.Polymer Physics》2006,44(16):2201-2225
The direct methanol fuel cell (DMFC) has the potential to replace lithium‐ion rechargeable batteries in portable electronic devices, but currently experiences significant power density and efficiency losses due to high methanol crossover through polymer electrolyte membranes (PEMs). Numerous publications document the synthesis and characterization of new PEMs for the DMFC. This article reviews this research, transport phenomena in PEMs, and experimental techniques used to evaluate new PEMs for the DMFC. Although many PEMs do not show significant improvements over Nafion®, the benchmark PEM in DMFCs, experimental results show that several new PEMs exhibit lower methanol crossover at similar proton conductivities and/or higher DMFC power densities. These results and recommendations for future research are discussed. © 2006 Wiley Periodicals, Inc. J Polym Sci Parts B: Polym Phys 44: 2201–2225, 2006 相似文献
3.
水溶性聚酯的结构和性能 总被引:2,自引:0,他引:2
由对苯二甲酸二甲酯、间苯二甲酸、间苯二甲酸二甲酯5-磺酸钠与乙二醇等共缩聚合成的PET型水溶性聚酯(WSP)是一种新型的水溶性聚合物,在化纤、纺织、涂料、粘合剂、电子、油墨等领域有着广泛的应用前景.化纤领域超细纤维新材料的研究、开发和生产,迫切需要一... 相似文献
4.
5.
6.
聚电解质溶液中2.6-ANS探针的荧光谱研究 总被引:1,自引:0,他引:1
本文合成了2.6—ANS荧光探针分子,并在含有不同外加盐的NaPSS溶液中测定了探针的荧光发射光谱。结果表明:探针的荧光强度随Cs增大而增大,而探针光谱的最大发射波长和半波宽度随Cs增大而减小。当Cs达到一定值时,荧光谱参数与Cs关系曲线出现转折点,此时聚离了链以“类胶束”状态存在。 相似文献
7.
We investigate the construction of long, stable hybrid threadlike micelles consisting of polyelectrolytes and oppositely charged surfactants in aqueous solution and examine the physicochemical features such as their structure and viscoelastic behavior in aqueous solution. The most important point for their construction is the careful control of interactions, especially electrostatic interactions, caused between the surfactants and polyelectrolytes. Incorporated polyelectrolytes are fully extended in these hybrid threadlike micelles irrespective of the molecular weight of the polymer. The viscoelastic behavior of the hybrid threadlike micellar solution is similar to that of ordinary threadlike micellar systems consisting of low‐molecular‐weight substances. However, the inclusion of polymers in the micelles causes differences in their mechanical properties. 相似文献
8.
Emilie Barriau Holger Frey Anton Kiry Manfred Stamm Franziska Gröhn 《Colloid and polymer science》2006,284(11):1293-1301
The preparation of carboxylated hyperbranched polyglycerols of narrow polydispersity was achieved by modification (78–90%) of the hydroxyl end groups via Michael addition of acrylonitrile, followed by hydrolysis. High conversion could only be achieved for low molecular weight starting materials (520 and 1,030 g mol−1). The solution properties of the resulting materials were investigated by dynamic light scattering (DLS), showing the formation of large aggregates with size depending on the pH value. After deposition on a negatively charged mica surface, the structures observed by atomic force microscope (AFM) show the coexistence of aggregates and single macromolecules. Most interesting, in the case of the lower molecular weight sample (PG 520 g mol−1), extended and ordered terrace structures were formed, which are unprecedented for hyperbranched polymers and are of interest for surface modification in general. 相似文献
9.
Highly hydrophobically modified (with n-dodecylamide chain) linear poly(acrylic acid)s (HHMPAAH) and poly(sodium acrylate)s (HHMPAANa) with various degrees of grafting
(τ) were synthesized and used as emulsifiers of the n-dodecane/water system. The type of emulsion, oil in water (O/W) or water in oil (W/O), was investigated as a function of
the polymer chemical structure (τ, salt or acid form of the copolymer) and aqueous phase electrolyte concentration (NaNO3). Increasing τ and/or salt concentration was found to favor the formation of inverse emulsions. Direct liquid–liquid dispersions
are more likely to form with poly(sodium acrylate)s than with poly(acrylic acid)s. Hence, field variables such as τ, pH and
ionic strength are relevant parameters to control emulsion type. Moreover, a balanced polyelectrolyte neither soluble in oil
nor in water was synthesized for the first time. With this original emulsifier, the dispersion type was found to change from
O/W to W/O with polymer salting out. The work provides convenient model system for fundamental studies of polymer conformation
at liquid–liquid interfaces.
Received: 31 March 1998 Accepted: 30 April 1998 相似文献
10.
Yinghong Sheng Jerzy Leszczynski Thuc-Quyen Nguyen Anu Bamgbelu 《Structural chemistry》2007,18(6):827-832
A theoretical study using density functional theory was performed to understand the structure/property relationship of the
cationic conjugated polyelectrolytes, poly[9,9-bis-(6′-N,N,N-trimethylammonium) hexyl] fluorene-alt-4,7-(2,1,3-benzothiadiazole)] (PFBT-X, where X = Br). The torsion angle between the fluorene and benzothiadiazole units in the PFBT monomer was found to substantially affect
the structural and electronic properties of the cationic PFBT monomer. The changes of geometrical parameter, HOMO and LUMO energy levels, and band gap, as well as the absorption maximum
are discussed in terms of the torsion in the PFBT monomer structure. For comparison, its neutral analogue, the monomer of
poly(9,9-di-n-octylfluorene-alt-benzothiadiazole) (F8BT) was also studied. The length of conjugation backbone was also examined. 相似文献