全文获取类型
收费全文 | 237275篇 |
免费 | 1975篇 |
国内免费 | 726篇 |
专业分类
化学 | 130201篇 |
晶体学 | 3390篇 |
力学 | 9033篇 |
综合类 | 15篇 |
数学 | 26586篇 |
物理学 | 70751篇 |
出版年
2021年 | 2098篇 |
2020年 | 2293篇 |
2019年 | 2555篇 |
2018年 | 3577篇 |
2017年 | 3455篇 |
2016年 | 4838篇 |
2015年 | 2848篇 |
2014年 | 4354篇 |
2013年 | 10124篇 |
2012年 | 8005篇 |
2011年 | 9672篇 |
2010年 | 6775篇 |
2009年 | 6586篇 |
2008年 | 9171篇 |
2007年 | 9228篇 |
2006年 | 8562篇 |
2005年 | 8251篇 |
2004年 | 7525篇 |
2003年 | 6572篇 |
2002年 | 6102篇 |
2001年 | 6406篇 |
2000年 | 5137篇 |
1999年 | 3754篇 |
1998年 | 3242篇 |
1997年 | 3274篇 |
1996年 | 3143篇 |
1995年 | 2596篇 |
1994年 | 2698篇 |
1993年 | 2755篇 |
1992年 | 2887篇 |
1991年 | 2886篇 |
1990年 | 2744篇 |
1989年 | 2708篇 |
1988年 | 2616篇 |
1987年 | 2591篇 |
1986年 | 2508篇 |
1985年 | 3232篇 |
1984年 | 3376篇 |
1983年 | 2719篇 |
1982年 | 2996篇 |
1981年 | 2853篇 |
1980年 | 2645篇 |
1979年 | 2853篇 |
1978年 | 2980篇 |
1977年 | 2979篇 |
1976年 | 2952篇 |
1975年 | 2791篇 |
1974年 | 2782篇 |
1973年 | 2915篇 |
1972年 | 1918篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A. Filarowski A. Koll A. Kochel J. Kalenik P. E. Hansen 《Journal of Molecular Structure》2004,700(1-3):67-72
The crystal structures of two ortho-hydroxy ketones (5-chloro-2-hydroxyacetophenone (I K) and 3,5-dichloro-2-hydroxyacetophenone (II K)) have been determined with X-ray diffraction at 100 K. A comparison of steric effects on properties of pseudoaromatic hydrogen bonds in ortho-hydroxy acetophenone and ortho-hydroxy ketimines have been carried out with the application of crystallographic data.
Nuclear quadrupole resonance (NQR) spectra have been measured and interpreted. 相似文献
992.
S. Yu. Ketkov H. L. Selzle E. W. Schlag S. N. Titova L. V. Kalakutskaya 《Optics and Spectroscopy》2004,97(4):567-571
Two-color photoionization of nickelocene molecules cooled in a supersonic jet is performed using a tunable nanosecond pulsed laser. The first stage of the multiphoton excitation is the transition from the highest occupied molecular orbital of nickelocene to the lowest Rydberg level. Conditions are found under which molecular ions (η 5-C5H5)2Ni+ are the only product of the multiphoton ionization in the one-color experiment. Irradiation of an excited molecule by an intense pulse of another laser increases significantly the yield of molecular ions. The dependence of the yield of (η5-C5H5)2Ni+ ions on the frequency of the second laser makes it possible to determine the adiabatic ionization potential of nickelocene as 6.138±0.012eV. 相似文献
993.
994.
995.
E. B. Kudashev 《Acoustical Physics》2003,49(5):545-549
It is shown that, in hydrodynamic noise measurements in the presence of acoustic noise acting upon the pressure fluctuation receiver, spatial filtering methods should provide the best results. Active methods are developed for suppressing the acoustic noise that affects a miniature receiver in the course of turbulent pressure fluctuation measurements. The methods are based on complicating the structure of the measuring transducer by introducing an extra compensating sensing element whose characteristics are identical with those of the main sensing element. The spatial filtering of small-scale turbulent pressure fluctuations by a finite-size electroacoustic transducer is used as the basis for the development of noise-compensated measuring systems, as well as methods of measuring the turbulent pressure fluctuations by receivers with noise compensation. A numerical study of the wave-number filtering of acoustic noise in wall pressure measurements by a noise-compensated receiver is performed. 相似文献
996.
C. Bizdadea C.C. Ciobîrc E.M. Cioroianu S.O. Saliu S.C. Sraru 《Annalen der Physik》2003,12(9):543-571
The local and manifestly covariant Lagrangian interactions in four spacetime dimensions that can be added to a “free” model that describes a generic matter theory and an abelian BF theory are constructed by means of deforming the solution to the master equation on behalf of specific cohomological techniques. 相似文献
997.
998.
Kvon Z. D. Tkachenko V. A. Plotnikov A. E. Sablikov V. A. Renard V. Portal J. C. 《JETP Letters》2004,79(1):36-39
JETP Letters - An experimental study of the two-, three-, and four-terminal resistance of a ballistic wire is carried out. The wire is fabricated on the basis of high-mobility 2D electron gas in an... 相似文献
999.
G. E. Volovik 《JETP Letters》2004,79(3):101-105
According to the Multiple Point Principle, our Universe is on the coexistence curve of two or more phases of the quantum vacuum. The coexistence of different quantum vacua can be regulated by the exchange of the global fermionic charges between the vacua, such as baryonic, leptonic, or family charge. If the coexistence is regulated by the baryonic charge, all the coexisting vacua exhibit the baryonic asymmetry. Due to the exchange of the baryonic charge between the vacuum and matter, which occurs above the electroweak transition, the baryonic asymmetry of the vacuum induces the baryonic asymmetry of matter in our Standard Model phase of the quantum vacuum. The present baryonic asymmetry of the Universe indicates that the characteristic energy scale, which regulates the equilibrium coexistence of different phases of quantum vacua, is about 106 GeV. 相似文献
1000.