全文获取类型
收费全文 | 6012篇 |
免费 | 714篇 |
国内免费 | 613篇 |
专业分类
化学 | 1788篇 |
晶体学 | 155篇 |
力学 | 946篇 |
综合类 | 62篇 |
数学 | 930篇 |
物理学 | 3458篇 |
出版年
2024年 | 10篇 |
2023年 | 39篇 |
2022年 | 85篇 |
2021年 | 102篇 |
2020年 | 107篇 |
2019年 | 85篇 |
2018年 | 98篇 |
2017年 | 145篇 |
2016年 | 172篇 |
2015年 | 146篇 |
2014年 | 279篇 |
2013年 | 347篇 |
2012年 | 330篇 |
2011年 | 353篇 |
2010年 | 305篇 |
2009年 | 380篇 |
2008年 | 392篇 |
2007年 | 422篇 |
2006年 | 341篇 |
2005年 | 378篇 |
2004年 | 356篇 |
2003年 | 258篇 |
2002年 | 265篇 |
2001年 | 237篇 |
2000年 | 207篇 |
1999年 | 180篇 |
1998年 | 166篇 |
1997年 | 174篇 |
1996年 | 133篇 |
1995年 | 111篇 |
1994年 | 95篇 |
1993年 | 91篇 |
1992年 | 105篇 |
1991年 | 55篇 |
1990年 | 52篇 |
1989年 | 49篇 |
1988年 | 53篇 |
1987年 | 47篇 |
1986年 | 30篇 |
1985年 | 22篇 |
1984年 | 26篇 |
1983年 | 14篇 |
1982年 | 16篇 |
1981年 | 15篇 |
1980年 | 4篇 |
1979年 | 21篇 |
1978年 | 14篇 |
1977年 | 8篇 |
1976年 | 8篇 |
1973年 | 3篇 |
排序方式: 共有7339条查询结果,搜索用时 0 毫秒
1.
We numerically solve the time-dependent Ginzburg–Landau equations for two-gap superconductors using the finite-element technique. The real-time simulation shows that at low magnetic field, the vortices in small-size samples tend to form clusters or other disorder structures. When the sample size is large, stripes appear in the pattern. These results are in good agreement with the previous experimental observations of the intriguing anomalous vortex pattern, providing a reliable theoretical basis for the future applications of multi-gap superconductors. 相似文献
2.
Mariusz Marć Marek Tobiszewski Bożena Zabiegała Miguel de la Guardia Jacek Namieśnik 《Analytica chimica acta》2015
This review summarizes the different tools and concepts that are commonly applied in air quality monitoring. The monitoring of atmosphere is extremely important as the air quality is an important problem for large communities. Main requirements for analytical devices used for monitoring include a long period of autonomic operation and portability. These instruments, however, are often characterized by poor analytical performance. Monitoring networks are the most common tools used for monitoring, so large-scale monitoring programmes are summarized here. Biomonitoring, as a cheap and convenient alternative to traditional sample collection, is becoming more and more popular, although its main drawback is the lack of standard procedures. Telemonitoring is another approach to air monitoring, which offers some interesting opportunities, such as ease of coverage of large or remote areas, constituting a complementary approach to traditional strategies; however, it requires huge costs. 相似文献
3.
4.
A new speckle shearing interferometer with simple setup is proposed. The interferometer can be converted easily from a speckle referenced speckle pattern interferometer into a speckle shearing interferometer and vice versa. A beamsplitter and a mirror are used to generate the shear. The amount of shear can be adjusted by simply rotating the mirror. The costs involved are low and it is particularly useful for fast inspection in non-destructive testing of structural integrity. Both the theoretical studies of the method of measurement and the experimental results are presented. 相似文献
5.
多普勒效应测试仪的改进 总被引:3,自引:0,他引:3
为了解决电磁波多普勒效应在实验室演示的困难,采用单片机和一系列大规模集成电路设计了一种演示电磁波多普勒效应的测试仪器,分析了电磁波的多普勒效应原理,给出了该仪器的组成结构,介绍了该仪器铁特点。 相似文献
6.
We obtain expressions for the energy spectrum widths of Rayleigh waves corresponding to their deformational coupling to Fermi and Boltzmann electrons in a two-dimensional layer near the surface of a semibounded solid. We evaluate the nonequilibrium energy of Rayleigh waves that depends on these widths and is caused by the same coupling to the corresponding hot electrons. We show that this energy is independent of the degeneracy degree of the electrons and is given by the mean energy of free Rayleigh waves heated up to temperature of the electrons. We find conditions under which the thermodynamics is determined by this nonequilibrium energy of Rayleigh waves in films of a certain thickness with Fermi electrons near the surface and by the equilibrium energy of bulk phonons in thicker samples. All the results are obtained using the Keldysh diagram technique applied to the case of semibounded media. 相似文献
7.
8.
R. Bairava Ganesh Hitoshi Matsuo Takahiro Kawamura Yoshihiro Kangawa Koji Arafune Yoshio Ohshita Masafumi Yamaguchi Koichi Kakimoto 《Journal of Crystal Growth》2008,310(11):2697-2701
Multicrystalline silicon was grown by unidirectional solidification method using the accelerated crucible rotation technique. The application of the accelerated crucible rotation technique in unidirectional solidification method induced growth striations across the axial direction of the grown crystal. This striation pattern was observed from carbon concentration distribution, obtained by using Fourier transform infrared spectroscopy. The generated striation pattern was found to be weak and discontinuous. Some striations were absent, probably due to back melting, caused during each crucible rotation. From the growth striations and applied time period in crucible rotation, the growth rate was estimated by using Fourier transformation analysis. 相似文献
9.
CONG Fuzhong & LI YongSchool of Mathematics Information Science Shandong Institute of Business Technology Yantai China Office of Mathematics Changchun Flight Academy of the Air Force Changchun China Department of Mathematics Jilin University Changchun China 《中国科学A辑(英文版)》2004,47(5):675-686
An effective stability result for generalized Hamiltonian systems is obtained by applying the simultaneous approximation technique due to Lochak. Among these systems, dimensions of action variables and angle variables might be distinct. 相似文献
10.
Hybrid numerical—experimental approach for investigation of dynamics of microcantilever relay system
V. Ostasevicius S. Tamulevicius A. Palevicius M. Ragulskis R. Palevicius V. Grigaliunas 《Optics and Lasers in Engineering》2005,43(1):199
The time average holography measurements of the vibrating microelectromechanical switch (MEMS) were performed in this study. Experimental measurement results exhibit good agreement with computer generated holographic interferogram analysis. The validation of experimental investigations versus numerical analysis provides the necessary background to analyze the dynamical characteristics of micromechanical systems in virtual numerical environments. Direct application of fringe counting techniques for reconstruction of motion from time average holograms cannot be straightforward if the analyzed micromechanical systems contain motion limiters. Modifications of a classical time average holographic technique enable qualitative analysis of MEMS and can be applied for investigation of dynamical properties of much broader classes of MEMS systems. 相似文献