全文获取类型
收费全文 | 111326篇 |
免费 | 7117篇 |
国内免费 | 6057篇 |
专业分类
化学 | 49549篇 |
晶体学 | 1335篇 |
力学 | 8801篇 |
综合类 | 395篇 |
数学 | 35654篇 |
物理学 | 28766篇 |
出版年
2023年 | 623篇 |
2022年 | 910篇 |
2021年 | 1227篇 |
2020年 | 1426篇 |
2019年 | 1488篇 |
2018年 | 11441篇 |
2017年 | 11314篇 |
2016年 | 7645篇 |
2015年 | 2703篇 |
2014年 | 2585篇 |
2013年 | 3191篇 |
2012年 | 7109篇 |
2011年 | 13826篇 |
2010年 | 8138篇 |
2009年 | 8591篇 |
2008年 | 9345篇 |
2007年 | 11030篇 |
2006年 | 2429篇 |
2005年 | 3063篇 |
2004年 | 2843篇 |
2003年 | 3056篇 |
2002年 | 2134篇 |
2001年 | 1164篇 |
2000年 | 1027篇 |
1999年 | 764篇 |
1998年 | 628篇 |
1997年 | 537篇 |
1996年 | 535篇 |
1995年 | 396篇 |
1994年 | 357篇 |
1993年 | 310篇 |
1992年 | 226篇 |
1991年 | 203篇 |
1990年 | 187篇 |
1989年 | 144篇 |
1988年 | 137篇 |
1987年 | 118篇 |
1986年 | 127篇 |
1985年 | 92篇 |
1984年 | 66篇 |
1983年 | 64篇 |
1982年 | 54篇 |
1981年 | 52篇 |
1980年 | 55篇 |
1979年 | 61篇 |
1978年 | 41篇 |
1914年 | 46篇 |
1912年 | 41篇 |
1909年 | 42篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 781 毫秒
41.
42.
We demonstrate a harmonically pumped femtosecond optical parametric oscillator(OPO)laser using a frequency-doubled mode-locked Yb:KGW laser at a repetition rate of 75.5 MHz as the pump laser.Based on a bismuth borate nonlinear crystal,repetition rates up to 1.13 GHz are realized,which is 15 times that of the pump laser.The signal wavelength is tunable from 700 nm to 887 nm.The maximum power of the signal is 207 m W at the central wavelength of 750 nm and the shortest pulse duration is 117 fs at 780 nm.The beam quality(M^2 factor)in the horizontal and vertical directions of the output beam are 1.077 and 1.141,respectively. 相似文献
43.
Journal of Statistical Physics - In this paper, averaging principle for the time-dependent stochastic evolution equations (TDSEEs) with infinite delay is investigated. In proper non-Lipschitz... 相似文献
44.
Aequationes mathematicae - We discuss equivalence conditions for the non-existence of non-trivial meromorphic solutions to the Fermat Diophantine equation $$f^m(z)+g^n(z)=1$$ with integers $$m,n\ge... 相似文献
45.
S. V. Panin I. V. Vlasov V. P. Sergeev B. B. Ovechkin P. O. Marushchak Sunder Ramasubbu P. S. Lyubutin V. V. Titkov 《Physical Mesomechanics》2015,18(3):261-272
The structure and properties of 12Cr1MoV steel irradiated with a zirconium ion beam were studied by optical microscopy, scanning electron microscopy, and micro- and nanoindentation. It is shown that the modification covers the entire cross-section of the irradiated specimens to a depth of 1 mm. The data on irradiation-induced structural changes are used to interpret the changes in mechanical properties of the irradiated specimens under static and cyclic loading. Particular attention is given to analysis of strain estimation by the digital image correlation method. 相似文献
46.
He Haidong Yang Haifeng Zhou Longpeng Chen Tianchi 《Journal of Russian Laser Research》2015,36(3):292-299
Ni–Co alloys have a wide range of applications in various fields owning to their excellent physical, chemical, and mechanical properties. In this paper, we prepare Ni–Co alloy coatings on 316L stain steel surfaces by electroplating. We present a novel approach utilizing a nanosecond laser to induce microtextures on Ni–Co alloy coatings. We study experimentally the effects of laser power and scanning rate on the surface morphologies of Ni–Co alloy coatings. The results indicate that the shape and size of induced microtextures can be controlled by the laser power and scanning rate. The size of grains increases with increase in the work current of the laser (WCL) at a certain scanning rate. With the WCL constant, the size of grains decreases with increase in scanning rate while their average height increases. It is a simple and easily-controlled method for the fabrication of microstructures on Ni–Co alloy coatings, which has promising applications in investigations of the properties of microtextured surfaces, such as friction, adhesion, and wetting. 相似文献
47.
48.
49.