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131.
We study discrete nonlinear maps in which the control parameter is itself “modulated” by another discrete nonlinear map. We
show that for a certain class of such maps, which includes for example the logistic map, the periodicity of the modulated
signal is either one, independent of the periodicity of the modulating signal, or its periodicity is an integral multiple
of the periodicity of the modulating signal or it is chaotic. 相似文献
132.
Narwal Sangeeta Kumar Sanjiv Verma Prabhakar Kumar 《Research on Chemical Intermediates》2021,47(4):1625-1641
Research on Chemical Intermediates - Chalcones are open-chain flavonoids which contains two aromatic rings are joined by 3-carbons α-, β-unsaturated carbonyl chain. The,... 相似文献
133.
The complexity of micropatterned cell constructs has been limited by difficulties in patterning more than two surface components on a culture substrate. Photolithography using multiple aligned masks is well established for generalized multicomponent patterning, but is often too harsh for biomolecules. We report a two-mask photolithographic process that is tuned to preserve bioactivity in patterns composed of covalently coupled poly(ethylene glycol) (PEG), adsorbed extracellular matrix protein (e.g., collagen I), and adsorbed serum proteins (e.g., vitronectin). Thereby, we pattern two cell types-primary hepatocytes and 3T3 fibroblasts-demonstrating control over contact and spacing (20-200 microm) between the two cell types for over one week. This method is applicable to the study of intercellular communication in cell biology and tissue engineering. 相似文献
134.
Sahoo S Husale S Karna S Nayak SK Ajayan PM 《Journal of the American Chemical Society》2011,133(11):4005-4009
Here we report a chemical-free, simple, and novel method in which a part from a silver-based anode is controllably used in a straightforward manner to produce silver nanoparticles (Ag NPs) in order to fabricate a controlled assembly of Ag NPs and single walled carbon nanotube (SWCNT) hybrid structures. The attachment and distribution of Ag NPs along SWCNTs have been investigated and characterized by field emission scanning electron microscopy (FESEM). We have achieved the decoration of SWCNTs with different densities of Ag NPs by changing the deposition time, the applied voltage, and the location of carbon nanotubes with respect to the anode. At low voltage, single silver nanoparticle is successfully attached at the open ends of SWCNTs whereas at high voltage, intermediate and full coverage densities of Ag NPs are observed. As voltage is further increased, fractals of Ag NPs along SWCNTs are observed. In addition, a device based on a Ag NPs-SWNT hybrid structure is used for the label-free detection of ssDNA molecules immobilized on it. We believe that the proposed method can be used to decorate and/or assemble metal nanoparticles or fractal patterns along SWCNTs with different novel metals such as gold, silver, and copper and can be exploited in various sensitive applications for fundamental research and nanotechnology. 相似文献
135.
Behavior of transition metal oxide (TMO) nanoparticles (Fe3O4, NiO, Co3O4, and Mn3O4) inserted in ion tracks has been studied in the presence of magnetic field. The special structure of ion tracks in dielectric
layer on semiconductors is known as TEMPOS—‘Tunable Electronic Materials with Pores in Oxide on Silicon’. TEMPOS structure
offers a high surface to volume ratio resulting in fast response time and high sensitivity of sensors fabricated by inserting
suitable materials in the ion tracks. We have already reported the behavior of ferrofluids (aqueous and non-aqueous) inserted
in the TEMPOS structures and its feasibility as earth’s magnetic field sensor. In continuation to this study, a comparative
study between different transition metal oxides inserted in the ion tracks is being presented here with an aim to understand
their response in confined geometry. This study shows that Fe3O4 (ferrofluid) is the best choice for ion track-based magnetic field sensor as compared to NiO, Co3O4, and Mn3O4. Its response to magnetic field can be tailored by the dilution of the ferrofluid and annealing. 相似文献
136.
Urea nitrate was found to be an inexpensive, acid-free, and safe nitrating agent that provides mononitration of phenols and substituted phenols in excellent yields with exclusive ortho-selectivity under microwave irradiation. Microwave assisted reactions reduced the reaction times substantially and enhanced the product yields from good to excellent within shorter reaction times. 相似文献
137.
Development of modified plastics has been studied through the LDPE-acylated starch blend films to examine the effect of different acyl groups and degrees of substitution(DS) on properties of films.Corn starch was modified with acetyl and butyryl groups and films were prepared by blending acylated starch with low density polyethylene(LDPE).Systematic studies were done to observe the effect of acyl groups,DS and starch concentration on the properties and biodegradability of the blend films.It was observed that blend films containing 5% acetylated and butyrylated starches of high DS(2.5,1.7) maintained 75% and 83% of tensile strength of LDPE films.Thermal analysis results indicated that acetylated and butyrylated starch blend films decomposed at 370 °C and 389 °C which were higher than the decomposition temperature of native starch film(349 °C).Scanning electron micrographs of blend films containing high DS acylated starch showed well dispersed starch particles due to improvement in dispersion between starch and LDPE.Water absorption capacity of high DS acetylated and butyrylated starch blend films(4.18% and 3.76%,respectively) was lower than that of native starch films(5%).This study has an advantage because of blown films prepared can be integrated with the present manufacturing systems without any other requirement. 相似文献
138.
Single crystals of NaBi(WO4)2 (NBW) have been grown by Czochralski technique, employing differently synthesized starting charge and different axial temperature gradients. The causes behind inherent problems related to compositional changes and associated lowering in crystallization temperature have been probed by analyzing XRD and DTA patterns of post growth residual charge. Presence of low melting phases viz. Na2WO4 and hitherto unreported compound Na5Bi(WO4)4 is thought to be responsible for the observed decrease in crystallization temperature. This problem was tackled by segregating pure phase material through re‐crystallization, under high axial temperature gradient. The use of re‐crystallized charge enabled transformation of almost the entire charge into a single crystal of high transparency. The effect of starting charge synthesis and temperature gradient on the optical transmission characteristics of NBW crystal has also been investigated. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
139.