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131.
低功耗设计在当前超大规模集成电路中越来越重要,本文以一种没有直流功耗.具有完全电压摆幅的低功耗动态CMOS三值反相器作为基础。结合简单三值差分逻辑(STDL)的结构.设计了一种低功耗动态三值CMOS D触发器.该触发器能很好地实现动态D触发器的逻辑功能.并且具有结构简单、芯片面积小、时钟简单等优点.Pspice模拟表明所设计的触发器还具有速度快、功耗低的优点.它比二值动态TSPCL D触发器节省近35%的能耗. 相似文献
132.
133.
PAUL KELLETT 《Fiber and Integrated Optics》2013,32(5):289-303
This article details the evolution of Ethernet into Gigabit Ethernet and how this LAN-based technology has undergone major transformations over time. From its data rates and distances to supported media and functionality, Ethernet has greatly improved, enabling it to surmount many of its former limitations and in so doing to expand beyond the LAN into the MAN and now even the WAN. In this article, Pioneer Consulting explores the evolution further by focusing on some of the major technological directions in the Ethernet equipment industry. 相似文献
134.
《Journal of Coordination Chemistry》2012,65(15):2497-2510
Reactions of fresh M(OH)2 (M = Zn2+, Cd2+) precipitate and (RS)-2-methylglutaric acid (H2MGL), 2,2′-bipyridine (bipy), or 1,10-phenanthroline (phen) in aqueous solution at 50°C afforded four new metal–organic complexes [Zn2(bipy)2(H2O)2(MGL)2] (1), [Zn2(phen)2(H2O)(MGL)2] (2), [Cd(bipy)(H2O)(MGL)] · 3H2O (3), and [Cd(phen)(H2O)(MGL)] · 2H2O (4), which were characterized by single crystal X-ray diffraction, IR spectra, TG/DTA analysis as well as fluorescence spectra. In 1, the [Zn(bipy)(H2O)]2+ moieties are linked by R- and S-2-methylglutarate anions to build up the centrosymmetric dinuclear [Zn2(bipy)2(H2O)2(MGL)2] molecules. In 2, the 1-D ribbon-like chains [Zn2(phen)2(H2O)(MGL)2] n can be visualized as from centrosymmetric dinuclear [Zn2(phen)2(H2O)2(MGL)2] units sharing common aqua ligands. Both 3 and 4 exhibit 1-D chains resulting from [Cd(bipy)(H2O)]2+ and [Cd(phen)(H2O)]2+, respectively, bridged alternately by R- and S-2-methylglutarate anions in bis-chelating fashion. The intermolecular and interchain π···π stacking interactions form supramolecular assemblies in 1 and 1-D chains in 2–4 into 2-D layers. The hydrogen bonded lattice H2O molecules are sandwiched between 2-D layers in 3 and 4. Fluorescence spectra of 1–4 exhibit LLCT π → π* transitions. 相似文献
135.
C. Herrero Latorre J. Álvarez MéndezAuthor VitaeJ. Barciela GarcíaAuthor Vitae S. García MartínAuthor VitaeR.M. Peña CrecenteAuthor Vitae 《Analytica chimica acta》2012
New materials have significant impact on the development of new methods and instrumentation for chemical analysis. From the discovery of carbon nanotubes in 1991, single and multi-walled carbon nanotubes – due to their high adsorption and desorption capacities – have been employed as sorption substrates in solid-phase extraction for the preconcentration of metal species from diverse matrices. Looking for successive improvements in sensitivity and selectivity, in the past few years, carbon nanotubes have been utilized as sorbents for solid phase extraction in three different ways: like as-grown, oxidized and functionalized nanotubes. In the present paper, an overview of the recent trends in the use of carbon nanotubes for solid phase extraction of metal species in environmental, biological and food samples is presented. The determination procedures involved the adsorption of metals on the nanotube surface, their quantitative desorption and subsequent measurement by means of atomic spectrometric techniques such as flame atomic absorption spectrometry, electrothermal atomic absorption spectrometry or inductively coupled plasma atomic emission spectrometry/mass spectrometry, among others. Synthesis, purification and types of carbon nanotubes, as well as the diverse chemical and physical strategies for their functionalization are described. Based on 140 references, the performance and general properties of the applications of solid phase extraction based on carbon nanotubes for metal species atomic spectrometric determination are discussed. 相似文献
136.
《Analytical letters》2012,45(11):837-842
Abstract An inverse voltametric method is described for determining traces of aluminum in beryllium and its compounds. The method is based on the electrochemical oxidation of the aluminum solochrome violett RS complex at a carbon paste electrode. The determination can be carried out in the ppm range without previous separation of other trace elements. 相似文献
137.
半导体光放大器(SOA)因其具有良好的光光互作用特性,包括交叉增益调制、交叉相位调制、交叉偏振调制以及四波混频等,在全光信号处理技术中已经获得了广泛的应用。利用SOA与光纤反馈可构成环形腔激光器S_FRL。在S—FRL中将SOA的光一光互作用特性与反馈条件相结合,可以改变孓FRI.的起振、抑制、选频等多种状态,从而构成不同功能的全光信号处理器件。在分析S—FRL激光振荡原理的基础上,提出了双环耦合的S-FRL,并以此为基础构成一种双环耦合的双稳态触发器,进而构成一种同步脉冲展宽器;还提出了一种级联的S-FRL,由此构成一种基于负逻辑的全光判决器。 相似文献
138.
Joanna Hetmaczyk ukasz Hetmaczyk Anna Migda‐Mikuli Edward Mikuli Aleksandra Weseucha‐Birczyska 《Journal of Raman spectroscopy : JRS》2012,43(8):1118-1125
[Ba(H2O)3](ClO4)2 between 90 and 300 K possesses two solid phases. One phase transition of the first‐order type at: = 211.3 K (on heating) and = 204.6 K (on cooling) was determined by differential scanning calorimetry. The entropy change value (ΔS ≈ 15 Jmol–1 K–1), associated with the observed phase transition, indicates a moderate degree of molecular dynamical disorder. Both, vibrational and reorientational motions of H2O ligands and ClO4– anions, in the high‐temperature and low‐temperature phases, were investigated by Fourier transform far‐infrared and middle‐infrared and Raman light scattering spectroscopies. The temperature dependences of the full‐width at half‐maximum values of the bands associated with ρw(H2O) mode, in both infrared (~570 cm–1) and Raman light scattering (~535 cm–1) spectra, suggest that the observed phase transition is not associated with a sudden change of a speed of the H2O reorientational motions. Ligands reorient fast, with correlation time of the order of several picoseconds, with a mean activation energy value Ea = 5.1 kJ mol–1 in both high and low temperature phases. On the other hand, measurements of temperature dependences of full‐width at half‐maximum values of the infrared band at ~460 cm–1, associated with δd(OClO)E mode, and Raman band at ~1105 cm–1, associated with νas(ClO)F2 mode, revealed the existence of a fast ClO4– reorientation in phase I and in phase II, with the Ea(I) and Ea(II) values equal to 8.0 and 6.5 kJ mol–1, respectively. These reorientational motions of ClO4– are slightly distorted at the TC. Fourier transform far‐infrared and middle‐infrared spectra with decreasing of temperature indicated characteristic changes at the vicinity of PT at TC, which suggested lowering of the crystal structure symmetry. All these experimental facts suggest that the discovered phase transition is associated with small change of H2O ligands and somewhat major change of ClO4– anions reorientational dynamics, and with insignificant change of the crystal structure, too. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
139.
E. B. Burgina V. G. Ponomareva V. P. Baltahinov V. G. Kostrovskiy 《Journal of Structural Chemistry》2005,46(4):608-618
IR and RS spectra, structural, thermodynamical and transport properties of CsHSO4 and CsHSO4/SiO2 composites have been investigated. It is shown that CsHSO4 is stabilized in composites in phase II (monoclinic modification), which turns into amorphous state with increasing silicon dioxide content. A formation of disordered highly conducting states of CsHSO4 in composites at the temperatures noticeably lower than superionic phase transition was stated. Bond length equalization in sulfate-ions, weakening of hydrogen bond system, and as a result easier proton transfer in composites in comparison with pure salt take place in these conducting states. Mechanism for formation of composites and their proton conductivity is proposed. 相似文献
140.
分析硬限幅多阈值神经元的工作原理,提出了运用多阈值神经元设计D触发器的方法.首先,用单个多阈值神经元设计锁存器;其次,利用两个锁存器设计了一次操作的主从型D触发器.本文设计的基于多阈值神经元的触发器与传统基于单阈值神经元的触发器相比减少了神经元的数量和连接数目、降低了复杂度、提高了稳定性.运用本文提出的多阈值神经元触发器,可以设计任意功能的神经网络时序电路. 相似文献