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991.
Jun‐Gill Kang Jung‐Pyo Hong Sung Kwon Kang 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(10):e432-e433
In the title compound, Na+·C6H8NO6?·2H2O, the sodium ion is coordinated in a distorted octahedral manner by two carboxylate O atoms and two water O atoms. Each of these water molecules bridges two adjacent Na ions, resulting in two four‐membered rings of the type Na–O–Na–O. 相似文献
992.
Yunghee Oh Byoung‐Chul Shin Dale Swenson Harold M. Goff Sung Kwon Kang 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(2):m57-m59
The title compound, [Fe(C44H8F20N4)]·2C6H6, contains a four‐coordinated FeII atom, which lies on a center of symmetry. The porphyrin macrocycle is planar, and the Fe—N bond distances are in the range 1.9891 (13)–1.9982 (13) Å. The spin state of the FeII atom is intermediate (S = 1), as confirmed by NMR spectroscopy. The asymmetric unit contains two half benzene molecules, each lying about an independent inversion centre; one of the benzene rings is located just below (and by inversion symmetry, another is just above) the Fe atom, where it interacts weakly with the porphyrin ring. 相似文献
993.
This paper introduces explicit conditions for some natural family of polynomials to define Pisot or Salem numbers, and reviews
related topics as well as their references. 相似文献
994.
Structure—Activity Relationships of the Peptide Ile-Ala-Val-Pro and Its Derivatives Revealed Using the Semi-Empirical AM1 Method 总被引:1,自引:0,他引:1
Several peptides with hypocholesterinemic properties were investigated in order to reveal structure-activity relationships.
The semi-empirical AM1 method and molecular dynamics were used to determine common structural properties of these peptides.
A mathematical model of the structure-activity relationship was obtained. According to this model, a hydrophobic part of these
peptides is a required structural element for their biological activity. The proline acts as a key component in these compounds.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 367–372, July–August, 2005. 相似文献
995.
Yun‐Hi Kim Qinghua Zhao Soon‐Ki Kwon 《Journal of polymer science. Part A, Polymer chemistry》2006,44(1):172-182
The copolymers that are composed of poly(fluorene) (PF), poly(p‐phenylene), and Poly(p‐phenylenevinylene) as backbone and a large 4′‐(N,N′‐diphenylamino)diphenyl or 4′‐(N,N′‐diphenylamino)phenyl as pendent group were synthesized by the nickel(0)‐mediated polycoupling. The composition of the obtained copolymers was confirmed by H NMR. All the copolymers possessed a high weight‐average molecular weight and good solubility in common organic solvents. As the content of triphenyl amine pendants increases, the copolymers showed increased thermal stability due to increased glass transition temperature and increased hole injection ability because of decreased onset of the oxidation potential. In the photoluminescence spectra of copolymers, poly (BDAV30‐co‐DHF70) and poly(BDAPV30‐co‐DHF70) showed efficient energy transfer. indium tin oxide/poly(styrene sulfonate)‐doped poly(3,4‐ethylene dioxythiophene)/poly (BDAV30‐co‐DHF70)/LiF/Al device showed maximum brightness of 2267 cd/m2 and efficiency of 0.80 cd/A, with turn‐on voltage at 9.1 V. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 172–182, 2006 相似文献
996.
Jung Kwon Oh Liza Deleebeeck Mitchell A. Winnik Jude Rademacher Rajeev Farwaha 《Journal of polymer science. Part A, Polymer chemistry》2005,43(22):5632-5642
We describe the synthesis and characterization of a weakly cross‐linked poly(methacrylic acid‐co‐ethyl acrylate) alkali‐swellable emulsion (ASE), as well as an investigation of its influence on the rate of polymer diffusion in latex films. The films examined were formed from poly(vinyl acetate‐co‐butyl acrylate) latex particles containing a small amount of acrylic acid as a comonomer. Polymer diffusion rates were monitored by the energy transfer technique. We found that the presence of the ASE component, either in the acid form or fully neutralized by ammonia or sodium hydroxide, had very little effect on the polymer diffusion rate. However, in the presence of 2 wt % NH4‐ASE, there was a small but significant increase in the polymer diffusion rate. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5632–5642, 2005 相似文献
997.
The liquid crystalline properties of two series of non-symmetric liquid crystal dimers consisting of cholesterol and Schiff base moieties interconnected by ω-oxyalkanoyl spacers of varying length are compared: one series (SBOC- n ) carry the octyloxy tail on the Schiff base mesogen, and the other (SBOF- n ) a perfluoroheptylmethyloxy tail. In general, compounds with the fluorinated alkoxy tail exhibited mesophases over a much wider temperature range than those with the alkoxy tail. The latter series favoured the formation of more diverse mesophases than the former. SBOC-4, -5 and -7, and SBOF-4, -5 and -10 formed the chiral smectic C phase. 相似文献
998.
Won Seok Chung Ohmyoung Kwon Du Seon Choi Seungho Park Young Ki Choi Joon Sik Lee 《Superlattices and Microstructures》2004,35(3-6):325
This paper suggests and demonstrates a novel flow measurement technique: tunable AC thermal anemometry, that allows simple integration, robust measurement and extremely high accuracy. The principle and simple theoretical analysis of the technique are presented. To find the optimal condition at which the phase lag becomes most sensitive to the flow speed change, the phase lag was measured scanning the heating frequency from 1 to 100 Hz, while the flow speed of ethanol was increased stepwise from 0 to 40 mm/s. The sensitivity of the phase lag depended on the heating frequency and the flow speed. It was possible to measure the average flow speed of 0.7 mm/s with the resolution of 0.1 mm/s at 4 Hz. 相似文献
999.
1000.
Yuan Li Eun J. Park Kwon T. Lim Keith P. Johnston Peter F. Green 《Journal of Polymer Science.Polymer Physics》2007,45(11):1313-1324
It has recently been shown that thin polymer films in the nanometer thickness range exhibit anomalous swelling maxima in supercritical CO2 (Sc‐Co2) in the vicinity of the critical point of CO2. The adsorption isotherm of CO2 on carbon black, silica surfaces, porous zeolites, and other surfaces, is known to exhibit anomalous maxima under similar CO2 conditions. It is believed that because CO2 possesses a low cohesive energy density, there would be an excess amount of CO2 at the surfaces of these materials and hence the CO2/polymer interface. This might cause excess CO2 in the polymer films near the free surface, and hence the swelling anomaly. In addition, an excess of CO2 would reside at the polymer/substrate and polymer/CO2 interfaces for entropic reasons. These interfacial effects, as have been suggested, should account for an overall excess of CO2 in a thin polymer film compared to the bulk, and would be responsible for the anomalous swelling. In this study, we use in situ spectroscopic ellipsometry to investigate the role of interfaces on the anomalous swelling of polymer thin films of varying initial thicknesses, h0, exposed to Sc‐CO2. We examined three homopolymers, poly(1,1′‐dihydroperflurooctyl methacrylate) (PFOMA), polystyrene (PS), poly(ethylene oxide) (PEO), that exhibit very different interactions with Sc‐CO2, and the diblock copolymer of PS‐b‐PFOMA. We show that the anomalous swelling cannot be solely explained by the excess adsorption of CO2 at interfaces. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1313–1324, 2007 相似文献