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31.
Highly Uniform YBO3 Hierarchical Architectures: Facile Synthesis and Tunable Luminescence Properties
Guang Jia Dr. Hongpeng You Prof. Kai Liu Yuhua Zheng Ning Guo Junjiao Jia Hongjie Zhang Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(9):2930-2937
Highly uniform pancake‐like YBO3 hierarchical architectures have been successfully prepared by a designed two‐step hydrothermal method. Yttrium precursor microprisms were first synthesized according to a simple hydrothermal route. Subsequently, nearly monodisperse multilayered YBO3 products with a pancake‐like shape were synthesized at the expense of the precursor during the hydrothermal process. The whole process was carried out under aqueous conditions without the use of any organic solvent, surfactant, or catalyst. The conversion process from the precursor to YBO3 products has been investigated by time‐dependent XRD experiments. Extending this method, other LnBO3 (Ln=Ho, Er, Tm, Yb) samples with well‐defined shape and dimensionality have also been obtained by a similar synthetic process. The luminescence colors of YBO3 samples co‐doped with Eu3+ and Tb3+ under ultraviolet or low‐voltage electron beam excitation can be tuned from red, through yellow and green‐yellow, to green by simply adjusting the relative doping concentrations of the activator ions. This merit of multicolor emissions in the visible region endows materials of this kind with potential application in the fields of light‐display systems and optoelectronic devices. 相似文献
32.
Agnieszka Iwan Patrice Rannou 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,74(1):174-179
The UV–vis absorption properties of undoped and doped 1,4-phenylenemethylidynenitrilo-1,4-phenylenenitrilomethylidyne (PAZ) in various temperatures are reported. It is demonstrated that the absorption spectra can be modified not only by changing the temperature from 193 K to 413 K, but also via acid–base doping involving the protonation of nitrogen atom in imine group. The use of special protonating agent, i.e. 1,2-(di-2-ethylhexyl)ester of 4-sulfophthalic acid (PSA) lead to the modification of the absorption spectrum of the PAZ. The imine band in UV–vis spectrum of the doped with the PSA polyazomethine is 85 nm red shifts in comparison with unprotonated one. The thermochromism of PAZ included the conformational changes in the conjugating backbone structure of the undoped and doped polyazomethine. 相似文献
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We present a comparative analysis of sequential versus hierarchical mechanisms of self-assembly in supramolecular architectures. The analysis is multifaceted, drawing on and inter-relating insights from a kinetic mean-field analysis and one based on the theory of finite Markov processes, complemented by Monte Carlo calculations. We give explicit results for two reaction pathways that are likely to dominate in early stages of self-assembly, and draw attention to experimental studies to which our results pertain: crystallization of zeolites from the bulk phase and aggregation of surface-supported supramolecular structures. Among the several conclusions that can be drawn from the theory and the simulations is a crossover from one mechanism to another, depending on the values of system parameters. 相似文献
35.
James R. Savage 《Theoretical chemistry accounts》1987,72(2):139-148
The large gains in computational capability which are required in the future by problems in computational quantum chemistry must come from advances in both parallel architectures and algorithms. The relation between algorithms and architecture is discussed, with examples of non-numerical algorithms for which future architectures should facilitate implementation. The use of timespace complexity trade-offs is discussed. A parallel language extension and architecture targeted towards general numerical and nonnumerical algorithms being developed by Myrias Research Corporation is briefly presented. 相似文献
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37.
Opto-Electronic Block-Cipher Based on Iteration of the 2-D Toggle Cellular Automata: Algorithm 总被引:2,自引:0,他引:2
Maria Madjarova Mitsugu Kakuta Takashi Obi Masahiro Yamaguchi Nagaaki Ohyama 《Optical Review》1999,6(2):110-117
Parallel architectures and algorithms may offer a solution to the system bottleneck arising from the need to encrypt a very large amount of data without compromising security. In this respect the use of cellular automata with their parallel, simple, regular and modular structure is very promising. We extend the blockcipher algorithm, based on the iterations of so called “toggle” cellular automata rules to two dimensions.The advantages are higher complexity of the crypt-analytical attacks and substantial increase in the speed of the algorithm. Due to its massive parallelism and interconnectivity, the algorithm is very suitable for opto-electronic implementation. 相似文献
38.
《Current Applied Physics》2020,20(9):1008-1012
Among the intermediate temperature (500–900 K) thermoelectric materials, both the p- and n-type lead telluride (PbTe) compounds have attracted extensive interests. Till date various approaches were adopted to enhance the thermoelectric performance of n-type PbTe-based materials as they show greater potential space for further improvement compared to p-type ones. Herein, a pseudo-ternary n-type (PbTe)0.95-x(Sb2Se3)x(PbS)0.05 system was designed and a large value of ZT = 1.61 at 850 K in case of x = 0.01 was achieved. Two factors are responsible for the improved thermoelectric performance. The incorporation of lead sulfide is the key factor to maintain a high level of power factor above 700 K and the multi-scale hierarchical architectures yield ultra-low thermal conductivity. 相似文献
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The principles of two-dimensional cellular processing are utilized to obtain the edges of a binary image in an optical shadow casted architecture. The processing steps, based on image logic algebra are introduced where operation kernels are set by the on/off states of four light sources. The input binary image is shifted, superimposed, then logically operated and finally decoded to obtain the edges. The whole process is controlled by a microcomputer. Experimentally simulated results are presented. 相似文献