全文获取类型
收费全文 | 815572篇 |
免费 | 7184篇 |
国内免费 | 2390篇 |
专业分类
化学 | 365514篇 |
晶体学 | 10679篇 |
力学 | 36171篇 |
综合类 | 20篇 |
数学 | 96439篇 |
物理学 | 223213篇 |
无线电 | 93110篇 |
出版年
2021年 | 7203篇 |
2020年 | 7816篇 |
2019年 | 8817篇 |
2018年 | 11554篇 |
2017年 | 11727篇 |
2016年 | 16360篇 |
2015年 | 9044篇 |
2014年 | 15362篇 |
2013年 | 35296篇 |
2012年 | 26901篇 |
2011年 | 32101篇 |
2010年 | 24375篇 |
2009年 | 25422篇 |
2008年 | 31948篇 |
2007年 | 32439篇 |
2006年 | 29936篇 |
2005年 | 27027篇 |
2004年 | 25206篇 |
2003年 | 22825篇 |
2002年 | 22544篇 |
2001年 | 24439篇 |
2000年 | 19505篇 |
1999年 | 15614篇 |
1998年 | 13723篇 |
1997年 | 13346篇 |
1996年 | 12388篇 |
1995年 | 11212篇 |
1994年 | 11198篇 |
1993年 | 10802篇 |
1992年 | 11335篇 |
1991年 | 11777篇 |
1990年 | 11178篇 |
1989年 | 10810篇 |
1988年 | 10229篇 |
1987年 | 9537篇 |
1986年 | 9030篇 |
1985年 | 11359篇 |
1984年 | 11719篇 |
1983年 | 9840篇 |
1982年 | 9958篇 |
1981年 | 9394篇 |
1980年 | 9021篇 |
1979年 | 9562篇 |
1978年 | 9772篇 |
1977年 | 9594篇 |
1976年 | 9472篇 |
1975年 | 9102篇 |
1974年 | 8920篇 |
1973年 | 9222篇 |
1972年 | 6607篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
R. Grosseuvres A. Comandini A. Bentaib N. Chaumeix 《Proceedings of the Combustion Institute》2019,37(2):1537-1546
The present work reports new experimental and numerical results of the combustion properties of hydrogen based mixtures diluted by nitrogen and steam. Spherical expanding flames have been studied in a spherical bomb over a large domain of equivalence ratios, initial temperatures and dilutions at an initial pressure of 100 kPa (Tini = 296, 363, 413 K; N2/O2 = 3.76, 5.67, 9; %Steam = 0, 20, 30). From these experiments, the laminar flame speed , the Markstein length L’, the activation energy Ea and the Zel'dovich β number have been determined. These parameters were also simulated using COSILAB® in order to verify the validity of the Mével et al. [1] detailed kinetic mechanism. Other parameters as the laminar flame thickness δ and the effective Lewis number Leeff were also simulated. These new results aim at providing an extended database that will be very useful in the hydrogen combustion hazard assessment for nuclear reactor power plant new design. 相似文献
2.
3.
4.
L. Resse L.G.S. Oliveira C.I.L. de Araujo A.R. Pereira R.L. Silva 《Physics letters. A》2019,383(14):1655-1659
In this work, we have used the MuMax3 software to simulate devices consisting of a ferromagnetic thin film placed over a heavy metal thin film. The devices are two interconnected partial-disks where a Néel domain wall is formed in the disks junction. In our simulations we investigate devices with disk radius nm and different distance d between the disks centers (from nm to nm). By applying strong sinusoidal external magnetic fields, we find a mechanism able to create, annihilate and even manipulate a skyrmion in each side of the device. This mechanism is discussed in terms of interactions between skyrmion and domain wall. The Néel domain wall formed in the center of the device interacts with the Néel skyrmion, leading to a process of transporting a skyrmion from one disk to the other periodically. Our results have relevance for potential applications in spintronics such as logical devices. 相似文献
5.
6.
7.
Stievano I.S. Maio I.A. Canavero F.G. Siviero C. 《Advanced Packaging, IEEE Transactions on》2006,29(1):31-38
This paper addresses the impact of device macromodels on the accuracy of signal integrity and performance predictions for critical digital interconnecting systems. It exploits nonlinear parametric models for both single-ended and differential devices, including the effects of power supply fluctuations and receiver bit detection. The analysis demonstrates that the use of well-designed macromodels dramatically speeds up the simulation as well it preserves timing accuracy even for long bit sequences. 相似文献
8.
This paper seeks to explore a method to accurately correct geometric distortions caused during the capture of three-dimensional (3-D) integral images. Such distortions are rotational and scaling errors which, if not corrected, will cause banding and moire effects on the replayed image. The method for calculating the angle of deviation in the 3-D Integral Images is based on Hough Transform. It allows detection of the angle necessary for correction of the rotational error. Experiments have been conducted on a number of 3-D integral image samples and it has been found that the proposed method produces results with accuracy of 0.05 deg 相似文献
9.
Note on B-splines, wavelet scaling functions, and Gabor frames 总被引:3,自引:0,他引:3
Grochenig K. Janssen A.J.E.M. Kaiblinger N. Pfander G.E. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2003,49(12):3318-3320
Let g be a continuous, compactly supported function on such that the integer translates of g constitute a partition of unity. We show that the Gabor system (g,a,b), with window g and time-shift and frequency-shift parameters a,b>0 has no lower frame bound larger than 0 if b=2,3,... and a>0. In particular, (g,a,b) is not a Gabor frame if g is a continuous, compactly supported wavelet scaling function and if b=2,3,... and a>0. We give an example for our result for the case that g=B/sub 1/, the triangle function supported by [-1,1], by showing pictures of the canonical dual corresponding to (g,a,b) where ab=1/4 and b crosses the lines N=2,3,. 相似文献
10.
de Oliveira J.C. Hosseini M. Shirmohammadi S. Malric F. Nourian S. El Saddik A. Georganas N.D. 《Multimedia, IEEE》2003,10(3):18-29
Using Java-based tools in multimedia collaborative environments accessed over the Internet can increase an application's client base. Most operating systems support Java, and its "compile once-run everywhere" architecture is easy to maintain and update. The Java-based tools presented here let users share Internet resources, including resources originally designed for single use. 相似文献