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991.
Li2SO4 as a model ionic conductor has received very much attention over several decades. Especially, in recent years Li2SO4 and Li2SO4-Al2O3 have been mentioned as promising proton conducting electrolytes for applications such as intermediate temperature fuel cells
and novel cogeneration systems regarding H2S handling devices. This has encouraged us to strive towards further improvement of the properties of the materials to meet
the demands of the applications.
In order to improve the properties of this system, a new process, a suspension technique, has been recently developed to prepare
nanostructured powder and thin film Li2SO4-Al2O3 membranes. The powders and thin films have a well crystallised structure composed of two phases, Li2SO4 and γ-Al2O3, and excellent mechanical strength. The thin film thickness is in the scale of a few to several mm with a smooth and shining
surface and a homogeneous macroscopic structure.
It is a very interesting phenomenon that all samples show no significant conductivity increase at the temperature of the phase
transition (∼ 577 °C) from β to α phase of pure Li2SO4. This transition has important significance for applications. The conductivity of the two-phase film materials has been greatly
enhanced, where the xLi2SO4-(1-x)Al2O3 (x=58) sample shows the highest conductivity, about 1 S/cm at 600 °C; the activation energy decreases with increasing Li2SO4 content. These results agree with the so called composite effect for the conductivity enhancement observed earlier for two-phase
bulk materials.
Based on the four-step proton conducting mechanism in sulphate-based materials, this work may propose a new mechanism. The
protons might jump in a water network associated with the water molecular re-orientation, which is accompanied with the single
proton jump of the four-step transportation among SO
4
2−
groups from one Li2SO4 molecule to another. The former mechanism occur in the interfacial region between the Li2SO4 and the Al2O3 grains, while the latter occur in the bulk of the Li2SO4 grains. These thin film materials are intended for use as proton conducting ceramic membranes in applications such as desulphurisation
and fuel cell co-generation plants.
Paper presented at the 5th Euroconference on Solid State Ionics, Benalmádena, Spain, Sept. 13–20, 1998. 相似文献
992.
IntroductionOrganicelectroluminescent(EL)deviceshavebecomeoneofthemostimportantsub-jectsbecauseoftheirpotentialapplicationasl... 相似文献
993.
应用Gauss随机场中峰的统计规律以及球对称塌缩模型计算了偏斜冷暗物质 (TCDM)、冷热混合暗物质 (MDM )以及宇宙学常数不为 0的暗物质 (ΛCDM )模型中的星系团 星系的交叉相关函数以及星系团周围物质的平均下落速度 .发现ΩΛ =0 .9,ΩC =0 .1 ,h =1的ΛCDM模型预言的交叉相关函数在尺度大于 1 0h-1·Mpc(H0 =1 0 0h·km·s-1·Mpc-1)时远大于观测得到的结果 .其他模型的预言则与在 ( 3~2 0 )h-1·Mpc尺度上的观测相容 .计算结果可用于与新的观测结果相比较 ,从而对暗物质的本质及偏袒因子b提出限制. 相似文献
994.
一种新的Eu3+配合物有机薄膜电致发光 总被引:3,自引:0,他引:3
自从C. W. Tang[1]百次发表高效、高亮度双层结构有机薄膜电致发光(EL)器件以来,由于其驱动电压低、可做成大面积及制作工艺简单等优点,使其在平板显示和显像领域具有巨大应用潜力而成为研究热点.可是大多数有机小分子和聚合物材料制作的有机薄膜电致发光器件的发射光谱谱带很宽,半高宽一般在100nm-200nm,色纯度不好,不利于显示和显像.于是寻找场致发光谱带窄、亮度高的有机材料就显得非常重要. 相似文献
995.
Halogenation of the potassium or silver salts of bis(trifluoromethanesulfonyl)methane (CF3SO2)2CH2 and its cyclo analogues 1 with N-fluoro-bis(trifluoromethanesulfonyl)imine [(CF3SO2)2-NF], chlorine or bromine gave good yields of the corresponding α-halo disulfone (CF3SO2)2CHX and cyclo analogues 9, 10. The chemical transformation of these fluorinated α-halo-disulfones are described. 相似文献
996.
文章着重研究了市场需求服从正态分布时参数估计误差变化对产品开发决策正确性的影响。通过实例分析,得到了处理这类问题的方法。文章进而给出了需求为有限方差与数学期望的一般随机量的处理方法,还给出了对Poisson变量的分析公式。 相似文献
997.
Bin Kang Cheng 《Physics letters. A》1984,103(8):357-362
Path integration of the harmonic oscillator with a two-time quadratic action characterizing memory effects is given in terms of the solutions of some integrodifferential equations. The exact propagator in closed form is then obtained for the specific kernel introduced by Feynman in the polaron problem. 相似文献
998.
999.
Tip-enhanced Raman spectroscopy (TERS) is based on the optical excitation of localized surface plasmons in the tip-substrate cavity, which provides a large but local field enhancement near the tip apex. We report on TERS with smooth single crystalline surfaces as substrates. The adsorbates were CN- ions at Au(111) and malachite green isothiocyanate (MGITC) molecules at Au(111) and Pt(110) using either Au or Ir tips. The data analysis yields Raman enhancements of about 4 x 10(5) for CN- and up to 10(6) for MGITC at Au(111) with a Au tip, probing an area of less than 100 nm radius. 相似文献
1000.
Fluorescent reagent sodium 1-naphthylamine diacetate (NADA) was assembled onto gold electrodes via its electrostatic interaction with cysteine (Cys) that was directly assembled on the gold electrode surface. Formation of the self-assembled bilayers was confirmed and primarily characterized by cyclic voltammetry and X-ray photoelectron spectra (XPS). The Cys modification of the gold electrode prevented direct adsorption of NADA onto the gold electrode and hence eliminated fluorescence quenching by gold. Strong fluorescence was observed from the NADA self-assembled bilayers at gold surface and was highly efficiently quenched by Cu2+ that allowed for an extremely highly sensitive detection of Cu2+ with a detection limit of 0.2 ppt and quantitative detection range of 0.5–9 ppt. The fluorescence from NADA/Cys/Au can be easily regenerated and therefore the present report showed a reusable method for immobilizing reagent in fabricating fluorescent chemosensors. 相似文献