全文获取类型
收费全文 | 6505篇 |
免费 | 1038篇 |
国内免费 | 688篇 |
专业分类
化学 | 2643篇 |
晶体学 | 98篇 |
力学 | 1025篇 |
综合类 | 75篇 |
数学 | 1375篇 |
物理学 | 3015篇 |
出版年
2024年 | 7篇 |
2023年 | 47篇 |
2022年 | 113篇 |
2021年 | 113篇 |
2020年 | 173篇 |
2019年 | 206篇 |
2018年 | 189篇 |
2017年 | 262篇 |
2016年 | 315篇 |
2015年 | 356篇 |
2014年 | 343篇 |
2013年 | 504篇 |
2012年 | 368篇 |
2011年 | 430篇 |
2010年 | 304篇 |
2009年 | 382篇 |
2008年 | 387篇 |
2007年 | 394篇 |
2006年 | 387篇 |
2005年 | 333篇 |
2004年 | 285篇 |
2003年 | 312篇 |
2002年 | 298篇 |
2001年 | 252篇 |
2000年 | 251篇 |
1999年 | 229篇 |
1998年 | 195篇 |
1997年 | 144篇 |
1996年 | 124篇 |
1995年 | 97篇 |
1994年 | 67篇 |
1993年 | 48篇 |
1992年 | 62篇 |
1991年 | 38篇 |
1990年 | 30篇 |
1989年 | 27篇 |
1988年 | 21篇 |
1987年 | 12篇 |
1986年 | 19篇 |
1985年 | 25篇 |
1984年 | 20篇 |
1983年 | 8篇 |
1982年 | 12篇 |
1981年 | 16篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1974年 | 2篇 |
1957年 | 2篇 |
排序方式: 共有8231条查询结果,搜索用时 531 毫秒
31.
Myung-Soon Lee 《Applied Surface Science》2006,252(14):5019-5025
We prepared high quality Au(1 1 1) film on Si wafer through the spin coating and thermal decomposition of a gold ink, spin-coated-and-fired (SCAF) Au film. The X-ray measurements, XRD and pole-figure analysis, showed that the SCAF Au film has a (1 1 1) out-of-plane orientation with a random in-plane orientation. In order to confirm the chemical activity of the SCAF Au film, we demonstrate the formation of patterned structures with the film by using soft lithography technique. The chemical activities of this physically stable SCAF Au film to the alkanethiols were at least equivalent those of physically deposited the Au films. The possibility of the mass production of micro patterned structure with the SCAF Au film was also demonstrated over the wide region on Si wafer by the microcontact lithography. These suggest that the Au film will help the easy fabrication of various nanosized devices on Si wafer and other substrates. 相似文献
32.
A. Ulyanenkov 《Applied Surface Science》2006,253(1):106-111
Several novel methods for evaluation and interpretation of X-ray data from modern nanostructures are presented along with their applications. The background of methods and their relations to fundamental problems of X-ray analysis is shortly described. The key features of LEPTOS software, which is designed for the analysis of X-ray data measured with various geometries and setups and implements all discussed techniques, are discussed. 相似文献
33.
Adhesion of zein to solid substrates has been studied using surface energy profiles as indices and by adhesion mapping using
atomic force microscopy (AFM). Different plasticizers like glycerol and sorbitol have been used to form mixed films with zein
and properties of these films are studied using surface energy profiles. Comparison of the results from the different mixed
samples with those from the pure zein films showed that force mapping could identify areas rich in protein. The adhesion maps
produced were deconvoluted from sample topography and contrasted with the data obtained from contact angle measurements. A
comparison of the two methods shows that the extent of contact angle hysteresis is indicative of both hydrophobicity of the
surface as well as the force of adhesion. Mechanical properties and microstructure of zein films prepared by casting from
solutions and using Langmuir-Blodgett film technique have been investigated. Pure zein seemed brittle and exhibited an essentially
linear relationship between stress and strain. Films with plasticizer were tougher than these films. In general, mixed films
showed better mechanical properties than pure films and had higher ultimate tensile strength and increased per cent elongation.
Further, the mixed films of zein showed a higher force of adhesion compared to the pure films. 相似文献
34.
35.
刘继成 《数学物理学报(B辑英文版)》2004,24(2)
Let X be a two parameter smooth semimartingale and (~X) be its process of the product variation. It is proved that (~X) can be approximated as D∞-limit of sums of its discrete product variations as the mesh of division tends to zero. Moreover, this result can be strengthen to yield the quasi sure convergence of sums by estimating the speed of the convergence. 相似文献
36.
汪巍 《数学的实践与认识》2004,34(3):103-109
首先引入了差分系统基于两种度量的极端稳定性概念 ,然后建立了一些关于差分系统 ( h0 ,h)极端稳定性 (极端一致稳定性 ,极端渐近稳定性 ,极端一致渐近稳定性 )的判定准则 .在所得到的定理中 ,对△ V的限制较弱 ,特别地 ,△V甚至可以恒为正 ,从而便于实际应用 . 相似文献
37.
P. C. Chen 《中国化学会会志》1995,42(5):755-760
Three ab initio calculations (HF/6-3IG, HF/6-3IG*, and HF/6-3IG**) on 2,4,6-trinitrotoluene were made, The results compare well with xray data, except dihedral angles of NO2 relative to the plane of the benzene ring. The deviations are attributed to packing forces and steric effects in the crystal. The most stable structure was a torsional angle 10° of the methyl top with the benzene ring, unlike toluene. The rotational barriers of the methyl top and the 4-nitro group are small. Hydrogen bonding, dipole moments and total atomic charges arc calculated. 相似文献
38.
39.
激光标线的原理和实验 总被引:1,自引:1,他引:0
根据几何光学知识分析了激光标线原理.理论和实验表明:激光标线长度与激光光束形状、光学元件形状及材料折射率有关.并讨论了激光标线向两侧扩展的原因. 相似文献
40.
Bai-suo JIN~ 《中国科学A辑(英文版)》2007,50(9):1303-1315
In the factor analysis model with large cross-section and time-series dimensions,we pro- pose a new method to estimate the number of factors.Specially if the idiosyncratic terms satisfy a linear time series model,the estimators of the parameters can be obtained in the time series model. The theoretical properties of the estimators are also explored.A simulation study and an empirical analysis are conducted. 相似文献