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71.
Chang Hyeong Lee Kyung Duk Park Bongsoo Jang 《Journal of mathematical chemistry》2013,51(7):1945-1960
In this paper, we present the multistage homotopy perturbation method for finding the solution of the chemical kinetics with nonlinear reactions. We develop a general scheme for finding the analytic solution of chemical reaction networks and apply it to motivating chemical examples such as the enzyme kinetics model and the Brusselator model. We illustrate the numerical result for the models and show the accuracy of the method. 相似文献
72.
How Does Solvation Affect the Binding of Hydrophilic Amino Saccharides to Cucurbit[7]uril with Exceptional Anomeric Selectivity?
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Jianping Wang Yoonjung Jang Jayshree K. Khedkar Jin Young Koo Yonghwi Kim Chang Jun Lee Young Min Rhee Kimoon Kim 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(44):15791-15799
Cucurbit[7]uril (CB[7]) is known to bind strongly to hydrophilic amino saccharide guests with exceptional α‐anomer selectivities under aqueous conditions. Single‐crystal X‐ray crystallography and computational methods were used to elucidate the reason behind this interesting phenomenon. The crystal structures of protonated galactosamine (GalN) and glucosamine (GluN) complexes confirm the inclusion of α anomers inside CB[7] and disclose the details of the host–guest binding. Whereas computed gas‐phase structures agree with these crystal structures, gas‐phase binding free energies show preferences for the β‐anomer complexes over their α counterparts, in striking contrast to the experimental results under aqueous conditions. However, when the solvation effect is considered, the binding structures drastically change and the preference for the α anomers is recovered. The α anomers also tend to bind more tightly and leave less space in the CB[7] cavity toward inclusion of only one water molecule, whereas loosely bound β anomers leave more space toward accommodating two water molecules, with markedly different hydrogen‐bonding natures. Surprisingly, entropy seems to contribute significantly to both anomeric discrimination and binding. This suggests that of all the driving factors for the strong complexation of the hydrophilic amino saccharide guests, water mediation plays a crucial role in the anomer discrimination. 相似文献
73.
Yu Na Lim Soo Kyung Chae Woongbin Yim Ji‐Yong Park Woojin Yoon Hoseop Yun Eunha Kim Seung Uk Son Hye‐Young Jang 《应用有机金属化学》2019,33(3)
The reaction of [(domppp) Pd (OAc)2] [domppp = 1,3‐bis (di‐o‐methoxyphenylphosphino)propane] and imidazolium‐functionalized carboxylic acids containing various anions (Br?, PF6?, SbF6? and BF4?) resulted in the formation of nano‐sized Pd (II) aggregates under template‐free conditions. The rate of formation of aggregates can be modulated by changing the anion, affecting the rate of polymerization of CO and olefins without fouling. Herein, we describe the analysis of Pd (II) catalysts by dynamic light scattering, atomic force microscopy, X‐ray photoelectron spectroscopy and X‐ray crystallography, and co‐ and terpolymerization results including the catalytic activity, and bulk density and molecular weight of polymers. 相似文献
74.
Wan Su Jung Hanui Ye Mateen Fahad Jun Bae Lee Su Ji Kim Jihui Jang 《Liquid crystals》2016,43(10):1495-1502
In this study, we postulated that the optical retardation magnitude could be used to evaluate the stability of the LC phase through the Mueller matrix polarimeter method in LC emulsion. In addition, we found that the increase of cetearyl alcohol concentration induced the more periodic dense lattice structure in crystalline phase of LC lamellae and the sorbitan olivate was relatively more responsible for higher ordering in LC phase compared to C12–20 alkyl glucoside in terms of molecular parallel packing on the basis of the optical retardation magnitude. Furthermore, it was confirmed that the LC emulsion had higher skin barrier function owing to lower TEWL and higher reflectance than ordinary emulsion on human skin and maintained a uniform phase without phase separation for 8 weeks. 相似文献
75.
Relationships between molecular structure and thermomechanical properties of bio‐based thermosetting polymers
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Jung Ho Yang Arun Srikanth Changwoon Jang Cameron F. Abrams 《Journal of Polymer Science.Polymer Physics》2017,55(3):285-292
Molecular dynamics simulations are used to study highly cross‐linked epoxy networks comprised of furanyl epoxy monomer, 2,5‐bis[(2‐oxiranylmethoxy)methyl]‐furan (BOF), that is cross‐linked by two furanyl amine hardeners, 5,5'‐methylenedifurfurylamine (DFDA) and 5,5'‐ethylidenedifurfirylamine (CH3‐DFDA). Important properties of these fully furan‐based systems, including room temperature density, glass transition temperature, and Young's modulus are found to agree with previous experimental results. We also compare the simulated and experimental values of four fully furan‐based thermosetting materials to those using the conventional resin diglycidyl ether of bisphenol A (DGEBA) cured with the two furanyl hardeners. Our simulation results predict a slight decrease in density and Young's modulus, but no impact on the glass transition temperature, upon adding the methyl group in DFDA. Detailed analyses of the MD trajectories reveal the underlying mechanisms responsible for the observed structure/property relations, which center on the lack of collinear covalent bonds in the BOF molecular structure. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 285–292 相似文献
76.
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78.
Jiyong Joo Myounghoon Choun Kwangdae Kim Sunghyun Uhm Young Dok Kim Jaeyoung Lee 《Current Applied Physics》2014,14(10):1374-1379
Water transport is critical to the successful implementation of polymer electrolyte fuel cells (PEFC), especially in long-term and dynamic operation in automotives. Liquid water appears in the fuel cells not only from the water generated at the cathode catalyst layer but also as a result of condensation of water vapor from the humidified gases. In this study, we report a simple approach to prepare a superhydrophobic gas diffusion layer by chemical vapor deposition of polydimethylsiloxane without significant change in pore size of gas diffusion layer unlike other approach adding hydrophobic agent such as polytetrafluoroethylene. A superhydrophobic coating on the GDL can be obtained, leading to exceptionally enhanced power performance and stability of PEFC especially at a high current where water transport becomes more critical. 相似文献
79.
80.
Byoung-Kee Jo Hyun-Don Kim Chun-Hag Jang Ki-Won Song Jang-Oo Lee 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(11):2293-2310
Abstract Interpolymer complex formation between basic polypeptides, poly(L- proline) Form I [PLP(I)], Form II [PLP(II)] and poly-4-hydroxy-L-proline (PHLP), and acidic polypeptides, poly(L-glutamic acid) (PLGA), poly(D- glutamic acid) (PDGA) and poly(L-aspartic acid) (PLAA), has been studied in water-methanol (1:2 v/v) mixed-solvent by viscometry, potentiometry, light scattering and circular dichroism (CD) measurements. It has been found that polymer complexes between basic- and acidic- polypeptides are formed via hydrogen bonding with a stoichiometric ratio of basic/acidic polypeptides =1:2 (in unit mole ratio) and that PLP(II) forms polymer complex more favorably with PLGA than with PLAA, and the complex of PLP(II) with PLGA is also more favorable than the complex formation of PHLP with PLGA. In addition, the complex formation is highly dependent on the conformation, especially the optical structure of the component polymers, i.e., the stereoselective complexation is observed. The PLGA having a right-handed helix at pH 3.2 formed the complex favorably and quickly with left-handed helix PLP(II), whereas PDGA having a left-handed helix at pH 3.2 favorably formed the complex with right-handed helix PLP(I). 相似文献