全文获取类型
收费全文 | 37283篇 |
免费 | 5492篇 |
国内免费 | 3656篇 |
专业分类
化学 | 25783篇 |
晶体学 | 358篇 |
力学 | 2227篇 |
综合类 | 241篇 |
数学 | 4280篇 |
物理学 | 13542篇 |
出版年
2024年 | 111篇 |
2023年 | 759篇 |
2022年 | 1224篇 |
2021年 | 1400篇 |
2020年 | 1443篇 |
2019年 | 1329篇 |
2018年 | 1150篇 |
2017年 | 1067篇 |
2016年 | 1611篇 |
2015年 | 1633篇 |
2014年 | 2004篇 |
2013年 | 2580篇 |
2012年 | 3253篇 |
2011年 | 3210篇 |
2010年 | 2180篇 |
2009年 | 2050篇 |
2008年 | 2203篇 |
2007年 | 1961篇 |
2006年 | 1843篇 |
2005年 | 1541篇 |
2004年 | 1305篇 |
2003年 | 985篇 |
2002年 | 895篇 |
2001年 | 739篇 |
2000年 | 691篇 |
1999年 | 829篇 |
1998年 | 693篇 |
1997年 | 635篇 |
1996年 | 705篇 |
1995年 | 601篇 |
1994年 | 550篇 |
1993年 | 470篇 |
1992年 | 449篇 |
1991年 | 364篇 |
1990年 | 324篇 |
1989年 | 236篇 |
1988年 | 216篇 |
1987年 | 198篇 |
1986年 | 141篇 |
1985年 | 156篇 |
1984年 | 135篇 |
1983年 | 116篇 |
1982年 | 80篇 |
1981年 | 59篇 |
1980年 | 49篇 |
1979年 | 33篇 |
1978年 | 26篇 |
1976年 | 27篇 |
1975年 | 31篇 |
1974年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
231.
WU Dan YIN YaJun XIE HuiMin SHANG YuanFang LI ChuanWei WU LiFu DAI XiangLu 《中国科学:物理学 力学 天文学(英文版)》2014,57(4):637-643
Wrinkling and buckling of nano-films on the compliant substrate are always induced due to thermal deformation mismatch.This paper proposes effective means to control the surface wrinkling of thin film on the compliant substrate,which exploits the curvatures of the curve cracks designed on the stiff film.The procedures of the method are summarized as:1)curve patterns are fabricated on the surface of PDMS(Polydimethylsiloxane)substrate and then the aluminum film with the thickness of several hundred nano-meters is deposited on the substrate;2)the curve patterns are transferred onto the aluminum film and lead to cracking of the film along the curves.The cracking redistributes the stress in the compressed film on the substrate;3)on the concave side of the curve,the wrinkling of the film surface is suppressed to be identified as shielding effect and on the convex side the wrinkling of the film surface is induced to be identified as inductive effect.The shielding and inductive effects make the dis-ordered wrinkling and buckling controllable.This phenomenon provides a potential application in the fabrication of flexible electronic devices. 相似文献
232.
Investigation of remelting and cladding processing with laminar plasma jets on several metals has been conducted looking for possible development of a new surface modification technique. The remelting tests illustrated that the new method could evidently improve the material microstructure and properties of cast iron. The cladding was done with Al2O3 ceramic powder on stainless steel. The energy dispersive spectra (EDS) analysis was used to determine the distribution of the major cladding element in the plasma-processed layers, for which the microstructure observations and hardness measurements were also performed. 相似文献
233.
A new terahertz dispersive device designed for single-shot spectral measurements of broadband terahertz pulses is proposed. With two-dimensional quasi-randomly distributed element design, the device exhibits approximately the dispersive property of single-order diffraction in far field. Its far-field diffraction pattern is experimentally verified employing a continuous terahertz source centered at 2.52 THz and a pyroelectric focal-plane-array camera, which is in good agreement with the numerical result. The device provides a new approach for direct single-shot spectral measurements of broadband terahertz waves. 相似文献
234.
Zn1-xCdx O films are grown on c-sapphire substrates by laser molecular beam epitaxy(LMBE) at different temperatures. Their crystallographic structures, compositions, surface electronic structures are investigated. The a-axis lattice constant of Zn0.95Cd0.05 O is 3.20. Moreover, the epitaxial relationship shows a 30°-in-plane rotation of the film with respect to the c-sapphire substrate. When the substrate temperatures arrives at 500℃, the in situ reflection high-energy electron diffraction(RHEED) pattern of Zn Cd O film shows sharp streaky pattern. The maximum Cd content of Zn Cd O film grown at low substrate temperatures increases up to about 29.6 at.%, which is close to that of the ceramic target. In situ ultraviolet photoelectron spectroscopy(UPS) measurements demonstrate that Zn Cd O film exhibits intense peaks at 4.7 e V and 10.7 e V below the Fermi level, which are assigned to the O 2p and Zn 3p states. Energetic distance between Zn 3d and Cd 4d is 0.60 e V. Above 470 nm, the thin film shows excellent optical transmission. 相似文献
235.
236.
The LNYAB self-doubling laser pumped by (LD) has been developed for the first time. The properties of the lasers are much better than those of NYAB self-doubling lasers pumped by LD. The LNYAB self-doubling laser pumped by LD can be operated in TEM_(00) mode with threshold pumping power of 3.6mW which is lower than that of LD pumped NYAB self-doubling lasers by 74%. The output power is 29mW at 0.531μm in green region with optical-to-optical efficiency of 4.8% which is higher than that of NYAB self-doubling laser by 20%. 相似文献
237.
238.
239.
Frabetti PL Cheung HW Cumalat JP Dallapiccola C Ginkel JF Greene SV Johns WE Nehring MS Butler JN Cihangir S Gaines I Garbincius PH Garren L Gourlay SA Harding DJ Kasper P Kreymer A Lebrun P Shukla S Bianco S Fabbri FL Sarwar S Zallo A Culbertson R Gardner RW Greene R Wiss J Alimonti G Bellini G Caccianiga B Cinquini L Di Corato M Giammarchi M Inzani P Leveraro F Malvezzi S Menasce D Meroni E Moroni L Pedrini D Perasso L Sala A Sala S Torretta D Vittone M Buchholz D Claes D Gobbi B O'Reilly B 《Physical review letters》1993,71(6):827-830
240.
本文简述了用电视摄象机进行工业尺寸测量的微分法与拟合法的基本原理,同时详细的讨论了各自所能达到的精度极限。本文用实验验证了理论计算的结果,最后对二维工件测量时,如何根据工件的不同形状与位置以及光学系统的特点,提出了在测量时工件的放置应该注意的问题以及对工件拐角处如何进行处理的方法。 相似文献