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151.
溶胶-凝胶法纳米ZnO薄膜的绿光发射 总被引:1,自引:1,他引:0
利用溶胶-凝胶法制备了纳米ZnO薄膜,室温下测量了样品的光致发光谱(PL)和X射线衍射谱(XRD),观测到中心波长在523 nm附近的绿色荧光发射,研究了纳米ZnO薄膜的绿光发射机制,证实了纳米ZnO薄膜绿光可见发射带来自氧空位(Vo)形成的浅施主能级和锌空位(Vzn)形成的浅受主能级之间的复合。 相似文献
152.
J.L. Sánchez Ll J.T. Elizalde-GalindoJ.A. Matutes-Aquino 《Solid State Communications》2003,127(7):527-530
High coercivity nanostructured YCo5 powders were successfully prepared by mechanical milling of as-cast alloys and subsequent vacuum annealing. Almost single phase YCo5 alloys, obtained by arc melting, were processed by high energy mechanical milling using a SPEX 8000 mill. After 4 h of milling, powders become nearly amorphous. DSC scans revealed the existence of an irreversible broad exothermic transition with a maximum at 516 °C associated with the crystallization process. Annealing in high vacuum at 800 °C during 2.5 min led to the formation of YCo5 nanoparticles with an average particle size of 12 nm. A high intrinsic coercivity of 7.23 kOe together with a σr/σs ratio of 0.75 were obtained. 相似文献
153.
根据实验数据,构造了接近实际纳米晶永磁Pr2Fe14B的样品,用微磁学有限元法进行了模拟计算.计算结果表明,晶界处各向异性的下降会导致矫顽力减小、剩磁值增大,而晶界处交换作用常数的减小则会使剩磁值减小、矫顽力增大.通过对实验样品的模拟研究发现,晶界处各向异性和交换作用常数的共同减小能够同时拟合出真实的矫顽力和剩磁值.模拟计算与实验在退磁曲线形状上的差距则说明模拟还存在不足.
关键词:
纳米晶永磁
磁滞回线
矫顽力
剩磁 相似文献
154.
A. Marshall B. Børresen G. Hagen S. Sunde M. Tsypkin R. Tunold 《Russian Journal of Electrochemistry》2006,42(10):1134-1140
Iridium-based oxides are highly active as oxygen evolving electrocatalysts in PEM water electrolyzers. In this work XRD reveals
that Ir-Sn oxides contain a single rutile phase with lattice parameters between those of pure IrO2 and SnO2. Addition of Ru leads to the synthesis of a core-shell type material due to the strong agglomeration of Ru colloids during
the preparation procedure. The shell of this material consists of an Ir-Sn-Ru oxide deficient in Ru relative to the bulk.
This leads to a decrease in the surface noble metal concentration (as found by XPS), which in turn results in a significant
reduction in electrochemically active surface area. Polarization analysis indicates that the addition of Ru can influence
the rate-determining step or mechanism by which oxygen is evolved. In a PEM water electrolysis cell, small additions of Sn
do not significantly reduce the operating performance, however larger additions cause a performance loss due to a reduction
in active surface area and increased ohmic resistance. When a pure IrO2 anode is used, a cell voltage is 1.61 V at 1 A cm−2 and 90°C.
Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 10, pp. 1260–1267.
The text was submitted by the authors in English. 相似文献
155.
V. Šepelák I. Bergmann A. Feldhoff P. Heitjans F. J. Litterst K. D. Becker 《Hyperfine Interactions》2005,165(1-4):81-87
The single-step synthesis of nanosized MgFe2O4 and NiFe2O4 via mechanochemical processing of binary oxide precursors is followed by 57Fe Mössbauer spectroscopy. Quantitative information is provided on both ionic and spin configurations in mechanosynthesized spinels. The response of the mechanosynthesized ferrite nanoparticles to changes in temperature is also studied. 相似文献
156.
采用阳极氧化水解法对染料敏化纳米TiO2薄膜太阳电池的光阳极进行不同方式的电沉积优化处理.借助x射线衍射仪对处理后的样品进行分析,通过超高分辨率场发射扫描电子显微镜对导电玻璃以及电沉积处理前后纳米多孔薄膜表面进行了粒径和形貌的扫描.染料敏化太阳电池实验测试结果表明,电沉积处理和修饰后可以明显提高光生电子的收集率,增大短路电流密度,提高电池效率.
关键词:
2')" href="#">纳米TiO2
染料敏化
电沉积
太阳电池 相似文献
157.
用失晕法测试了纳米锌镀层和0^#锌片在0.2mol/L硫酸介质中的腐蚀性能.结果表明纳米锌镀层的耐腐蚀性要远优于锌片,且在一定的实验条件下,纳米锌镀层的腐蚀速率为一常数.另外,本文还研究了溴化十六烷基吡啶和吡啶及其甲基衍生物在硫酸介质中对纳米锌镀层和0^#锌片的缓蚀性能.其中溴化十六烷基吡啶和3-甲基吡啶的缓蚀性能较好.并用密度泛函B3LYP方法和Onsager溶剂化模型,在6-31G水平上优化了溴化十六烷基毗啶、3-甲基吡啶和4-甲基毗啶分子的几何构型,用其电子结构数据探讨了它们的缓蚀机理。 相似文献
158.
M. Miglierini 《Hyperfine Interactions》2005,164(1-4):41-49
A controlled annealing of amorphous precursors represents a simple way of obtaining nanocrystalline alloys featuring interesting magnetic properties suitable for technical applications. They stem from the presence of crystalline nanograins embedded in the amorphous residual matrix which determine the resulting macroscopic parameters. In order to understand correlation between the microstructure and the resulting magnetic behaviour, Mössbauer spectrometry is used as a method of local probe analysis. Possibilities of this technique are discussed and representative examples of investigation of NANOPERM-type nanocrystalline alloys are provided. 相似文献
159.
A.M. Vichare D.G. Kanhere 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(1):89-94
Density based molecular dynamics has been used to investigate the ground state structures of heterogeneous binary clusters
Al13Lin, n
= 1, 2, 3, 4, 10, 19, 20, 21. Some of these structures have also been investigated by full Kohn-Sham based calculations. Our
earlier investigations have shown that in the Al-Li cluster, the ground state configurations are the ones where the Al atoms
form a core around which the Li atoms form a “cage”. In the present work, we have chosen the well-known Al13 icosahedron as the surface over which we study the evolution of the surface coverage as the number of Li atoms increases.
On the basis of the earlier work, we expect that the Al13Li20 cluster would be the most stable and indeed our simulations do yield such a novel fivefold symmetric stable structure formed
out of purely metal atoms. This icosahedral substrate is also used to study the coverage of the aluminum surface by lithium
atoms. For a small number of Li atoms, these studies suggest that the Li-Li dimerisation is not particularly favored.
Received: 24 October 1997 / Revised: 7 April 1998 / Accepted: 29 June 1998 相似文献
160.