全文获取类型
收费全文 | 11397篇 |
免费 | 2718篇 |
国内免费 | 1170篇 |
专业分类
化学 | 7626篇 |
晶体学 | 206篇 |
力学 | 113篇 |
综合类 | 71篇 |
数学 | 49篇 |
物理学 | 7220篇 |
出版年
2024年 | 9篇 |
2023年 | 112篇 |
2022年 | 257篇 |
2021年 | 303篇 |
2020年 | 397篇 |
2019年 | 294篇 |
2018年 | 315篇 |
2017年 | 314篇 |
2016年 | 465篇 |
2015年 | 518篇 |
2014年 | 600篇 |
2013年 | 1047篇 |
2012年 | 690篇 |
2011年 | 752篇 |
2010年 | 627篇 |
2009年 | 752篇 |
2008年 | 696篇 |
2007年 | 913篇 |
2006年 | 926篇 |
2005年 | 657篇 |
2004年 | 581篇 |
2003年 | 587篇 |
2002年 | 462篇 |
2001年 | 442篇 |
2000年 | 384篇 |
1999年 | 321篇 |
1998年 | 286篇 |
1997年 | 282篇 |
1996年 | 219篇 |
1995年 | 186篇 |
1994年 | 167篇 |
1993年 | 134篇 |
1992年 | 97篇 |
1991年 | 71篇 |
1990年 | 75篇 |
1989年 | 49篇 |
1988年 | 51篇 |
1987年 | 43篇 |
1986年 | 41篇 |
1985年 | 26篇 |
1984年 | 33篇 |
1983年 | 10篇 |
1982年 | 15篇 |
1981年 | 21篇 |
1980年 | 15篇 |
1979年 | 7篇 |
1978年 | 10篇 |
1975年 | 6篇 |
1974年 | 3篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
52.
Jun Fujii Giancarlo Panaccione Giorgio Rossi Giancarlo Trimarchi 《Surface science》2006,600(18):3884-3887
Bulk carbon impurities segregate at the Fe(1 0 0) surface and, upon thermal annealing, can form metastable surface phases with local and long range order and peculiar electronic properties. We present a surface science study of C-segregated Fe(1 0 0) with scanning tunneling microscopy, angle resolved photoemission, and ab initio calculations of the surface structure and electron states. In particular the c(3√2 × √2) structure, observed for 0.67 atomic layers of C segregated at the iron surface, is found to be due to self-organized carbon stripes made of zig-zag chains. The strong hybridization between C and Fe was observed in ARPES spectra. 相似文献
53.
建立一个描述低能电子在多元多层介质中散射的物理模型,运用MonteCarlo方法模拟低能电子在靶体胶衬底中的复杂散射过程,在此基础上通过大量计算研究入射束能、胶层厚度、衬底材料等不同曝光条件对抗蚀剂沉积能密度分布的影响,获得沉积能分布规律:适量的低束能、薄胶层、低原子序数衬底可以使前散射电子对胶中沉积能密度分布的贡献增大、背散射电子的贡献减小,从而提高曝光分辨率.
关键词:
电子束曝光
MonteCarlo方法
低能电子散射
能量沉积 相似文献
54.
55.
56.
The initial stage of cubic silicon carbide (3C-SiC) growth on a Si(0 0 1) surface using dimethylsilane (DMS) as a source gas was observed using scanning tunneling microscopy (STM) and reflection high-energy electron diffraction (RHEED). It was found that the dimer vacancies initially existing on the Si(0 0 1)-(2 × 1) surface were repaired by the Si atoms in DMS molecules, during the formation of the c(4 × 4) surface. From the STM measurement, nucleation of SiC was found to start when the Si surface was covered with the c(4 × 4) structure but before the appearance of SiC spots in the RHEED pattern. The growth mechanism of SiC islands was also discussed based on the results of RHEED, STM and temperature-programmed desorption (TPD). 相似文献
57.
Sadaharu Jo 《Applied Surface Science》2006,252(10):3514-3519
The morphologies and lattice structures of anthracene single crystals grown from the vapor phase were investigated using optical microscopy, phase contrast microscopy, atomic force microscopy (AFM), and X-ray diffraction analysis. Common morphologies with hexagonal large planes were observed irrespective of crystal size. The observation of certain surface morphologies with a phase contrast microscopy revealed that the spiral steps originated from screw dislocations present on the (0 0 1) planes. Moreover, the center and edge of the (0 0 1) planes had large curvatures, similar to hills. Resultantly, quarter-monolayer (ML) steps were observed on the large and flat planes between both hills. 相似文献
58.
P. Kavouras Th. Kehagias K. Chrissafis Ph. Komninou Th. Karakostas 《Journal of Thermal Analysis and Calorimetry》2006,86(3):715-719
Three batch compositions of pure oxides (SiO2,
Fe2O3, PbO, Na2O)
with equivalent SiO2, Fe2O3
and PbO contents and a gradually increased Na2O content
were vitrified through heating in a high temperature electric furnace and
subsequent quenching. The resulting vitreous products were thermally treated
in order to study the devitrification behaviour, under conditions designated
from differential thermal analysis experiments. Depending on the Na2O
content, crystal phase separation gave rise to the growth of acmite and hematite
or maghemite. A uniformly phase separated glass-ceramic material, with crystallites
of similar size and population density, was produced from devitrification
of the vitreous product with the higher Na2O content. 相似文献
59.
60.
江汉平原上空QTEC变化特征的统计分析 总被引:1,自引:0,他引:1
提出了一种观测台网用多接收机性能一致性的标定方法,并利用江汉平原GPS接收台网的观测数据,分析了该地区上空QTEC的日变化、季节变化、年变化和逐年变化的统计特征.标定结果表明,不同接收机之间的仪器偏差是从双频GPS卫星信标推算QTEC的主要误差来源之一,必须校正.统计分析证实,江汉平原上空QTEC的日变化特征同时受电离层和等离子层控制,其年变化以半年周期为主,峰值和谷值分别出现在两分点和两至点附近,QTEC值的逐年变化从太阳活动峰年到低年逐年下降,与以太阳黑子数为代表的太阳活动密切相关. 相似文献