全文获取类型
收费全文 | 12128篇 |
免费 | 2044篇 |
国内免费 | 2027篇 |
专业分类
化学 | 4757篇 |
晶体学 | 414篇 |
力学 | 751篇 |
综合类 | 72篇 |
数学 | 179篇 |
物理学 | 5360篇 |
无线电 | 4666篇 |
出版年
2024年 | 17篇 |
2023年 | 68篇 |
2022年 | 191篇 |
2021年 | 248篇 |
2020年 | 248篇 |
2019年 | 210篇 |
2018年 | 233篇 |
2017年 | 384篇 |
2016年 | 505篇 |
2015年 | 500篇 |
2014年 | 625篇 |
2013年 | 793篇 |
2012年 | 792篇 |
2011年 | 1033篇 |
2010年 | 841篇 |
2009年 | 926篇 |
2008年 | 926篇 |
2007年 | 1016篇 |
2006年 | 954篇 |
2005年 | 765篇 |
2004年 | 712篇 |
2003年 | 552篇 |
2002年 | 485篇 |
2001年 | 414篇 |
2000年 | 429篇 |
1999年 | 344篇 |
1998年 | 301篇 |
1997年 | 283篇 |
1996年 | 263篇 |
1995年 | 239篇 |
1994年 | 201篇 |
1993年 | 149篇 |
1992年 | 127篇 |
1991年 | 110篇 |
1990年 | 79篇 |
1989年 | 47篇 |
1988年 | 40篇 |
1987年 | 28篇 |
1986年 | 15篇 |
1985年 | 16篇 |
1984年 | 8篇 |
1983年 | 11篇 |
1982年 | 11篇 |
1981年 | 13篇 |
1980年 | 4篇 |
1979年 | 9篇 |
1978年 | 15篇 |
1976年 | 5篇 |
1975年 | 8篇 |
1973年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
81.
本文研究了采用锁定放大相干检测技术的等离子体光发射谱检测系统。用该系统检测了仅用CF4作为刻蚀气体刻蚀非晶硅基薄膜的等离子体光发射谱。分析了检测结果和刻蚀机理。 相似文献
82.
薄膜磁头磁轭制备工艺研究 总被引:1,自引:1,他引:0
本文重点讨论了用不同的工艺方法来制备薄膜磁头中的关键元件-磁轭。采用多次光刻的方法克服湿法工艺中磁性膜NiFe层的侧向钻蚀问题,从而实现对磁轭几何尺寸的精确控制,并对几种工艺方法的优缺点作了比较详细的分析。 相似文献
83.
厚膜导体Pd-Ag/Au、Pt-Pd-Au/Au平面复合结构,Pd-Ag/Au立体复合结构可使多种组装技术相互兼容。立体复合结构还可有效地降低导体线电阻,减少线损耗。而且,其超声键合性尤佳 相似文献
84.
Monocrystalline 6H-SiC thin films have been epitaxially grown on off-axis 6H-SiC {0001} substrates in the temperature range
of 1623–1873 K via chemical vapor deposition. The growth rate was a strong function of the growth temperature and the reactant
gas concentration. The activation energies for growth were 64 kJ/mole and 55 kJ/mole for the (0001) Si face and the (0001)
C face, respectively. The concentration of growth pits in the films increased as a function of decreasing deposition temperature,
increasing concentration of reactant gases and increasing off-axis orientation. Beta-SiC islands were also observed in the
epilayers when the (SiH4 + C2H4)/H2 ratio was ≥2.5:3000. 相似文献
85.
86.
波分复用系统中的交错复用器(Interleaver)技术 总被引:4,自引:1,他引:3
鉴于波分复用技术已成为光纤通信的发展方向,介绍几种新型的交错复用器的原理、结构等情况,对各种器件进行了比较。 相似文献
87.
Yunshan Dong 《Applied Surface Science》2006,252(14):5057-5062
A series of Zr-Si-N composite films with different Si contents were synthesized in an Ar and N2 mixture atmosphere by the bi-target reactive magnetron sputtering method. These films’ composition, microstructure and mechanical properties were characterized by energy dispersive spectroscopy, X-ray diffraction, scanning electron microscopy, atomic force microscopy and nanoindentation. Experimental results revealed that after the addition of silicon, Si3N4 interfacial phase formed on the surface of ZrN grains and prevented them from growing up. Zr-Si-N composite films were strengthened at low Si content with the hardness and elastic modulus reaching their maximum values of 29.8 and 352 GPa at 6.2 at% Si, respectively. With a further increase of Si content, the crystalline Zr-Si-N films gradually transformed into amorphous, accompanied with a remarkable fall of films’ mechanical properties. This limited enhancement of mechanical properties in the Zr-Si-N films may be due to the low wettability of Si3N4 on the surface of ZrN grains. 相似文献
88.
为了探索低温可调控ZnO薄膜沉积技术,提出了一种新的ZnO薄膜制备方法,即离化团簇束(ICB)法,并自行设计研制了应用该方法制备ZnO薄膜的专门装置.采用超音速喷嘴获得高速锌原子团簇束,用Hall等离子体源产生氧离子束离化锌原子团簇,获得了较高的离化率.在沉积过程中,可以通过调节衬底偏压、氩氧比、衬底加热温度等参数,来控制成膜的质量;应用这个装置成功地在硅衬底上制备的ZnO薄膜,经XRD和EDS检测,薄膜的c轴取向一致,Zn、O原子百分比接近于1:1,成膜质量好. 相似文献
89.
Chenghang Wang 《Applied Surface Science》2006,253(4):2282-2288
In this paper, thin films of titanium oxide imprinted with O,O-dimethyl-(2,4-dichlorophenoxyacetoxyl)(3′-nitrobenyl) methinephosphonate (Phi-NO2) were prepared via liquid phase deposition (LPD) method on a glassy carbon electrode. The imprinted molecular in the films was removed by treatment with immersion in CH2Cl2. X-ray diffraction (XRD) and electrochemical methods were introduced to show the evidence of the molecular imprinting phenomenon. It was also found that the recognition ability of the sensor depended on the substituents associated with tridimensional structures of the nitro-compounds. Under the optimized condition, the sensor showed better sensitivity, selectivity and reproducibility to the imprinted molecule and the linear relationship between the current and the concentration of analyte in the range of 0.1-50 μM was obtained. LPD proved to be a powerful method for imprinting titanium oxide thin sense films. 相似文献
90.
Jing-na Li Xiao-feng Wang Zheng-an Yao 《应用数学学报(英文版)》2007,23(3):421-432
In this paper, we propose a model in studying soft ferromagnetic films, which is readily accessible experimentally. By using penalty approximation and compensated compactness, we prove that the dynamical equation in thin film has a local weak solution. Moreover, the corresponding linear equation is also dealt with in great detail. 相似文献