全文获取类型
收费全文 | 433284篇 |
免费 | 2204篇 |
国内免费 | 847篇 |
专业分类
化学 | 179903篇 |
晶体学 | 5848篇 |
力学 | 27656篇 |
综合类 | 4篇 |
数学 | 90052篇 |
物理学 | 132872篇 |
出版年
2021年 | 3348篇 |
2020年 | 3735篇 |
2019年 | 4553篇 |
2018年 | 19971篇 |
2017年 | 20109篇 |
2016年 | 15676篇 |
2015年 | 5067篇 |
2014年 | 7652篇 |
2013年 | 13182篇 |
2012年 | 16588篇 |
2011年 | 28755篇 |
2010年 | 19271篇 |
2009年 | 19868篇 |
2008年 | 24076篇 |
2007年 | 27840篇 |
2006年 | 10968篇 |
2005年 | 13926篇 |
2004年 | 11916篇 |
2003年 | 12070篇 |
2002年 | 10320篇 |
2001年 | 8179篇 |
2000年 | 6735篇 |
1999年 | 4819篇 |
1998年 | 4581篇 |
1997年 | 4412篇 |
1996年 | 4177篇 |
1995年 | 3620篇 |
1994年 | 3608篇 |
1993年 | 3619篇 |
1992年 | 3559篇 |
1991年 | 3979篇 |
1990年 | 3960篇 |
1989年 | 3960篇 |
1988年 | 3725篇 |
1987年 | 3806篇 |
1986年 | 3489篇 |
1985年 | 4043篇 |
1984年 | 4280篇 |
1983年 | 3655篇 |
1982年 | 3871篇 |
1981年 | 3538篇 |
1980年 | 3302篇 |
1979年 | 3798篇 |
1978年 | 3877篇 |
1977年 | 3946篇 |
1976年 | 4054篇 |
1975年 | 3762篇 |
1974年 | 3615篇 |
1973年 | 3821篇 |
1972年 | 3243篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
982.
983.
E. V. Suchilkina 《Journal of Mathematical Sciences》2007,147(1):6510-6516
At the end of the twentieth century, in mathematical physics, the Knizhnik-Zamolodchikov equations for the root systems A
n
and their generalizations for the root systems of types B
n
, C
n
, and D were constructed. For the root system of type G
2, the vector version of the Knizhnik-Zamolodchikov equations was obtained by M. P. Zamakhovskii and V. P. Leksin. However,
the tensor version of these equations has remained unstudied. In this paper, the Knizhnik-Zamolodchikov equations associated
with the root system of type G
2 are considered.
__________
Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 38, Suzdal
Conference-2004, Part 3, 2006. 相似文献
984.
985.
986.
A. Puiu G. Giubileo G. Addolorato L. Revelli G. Gasbarrini R. Bellantone A. D’Amore C. P. Lombardi C. Carrozza 《Laser Physics》2007,17(4):448-452
Nowadays, there is high demand for sensitive gas sensors both for human and environmental monitoring. This paper deals with a high-resolution (0.2 ppb) laser-based photoacoustic spectroscopic system realized at ENEA Frascati, Italy, applied for monitoring stress in scuba divers during sustained immersion by analyzing breath samples. Blood tests and psychometric tests for scuba divers were performed at Catholic University in Rome. Results will be reported and discussed. 相似文献
987.
M. I. Kurkin 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(11):1607-1609
The conditions of compatibility of the magnetic sublattice hypothesis with the requirements of quantum theory have been derived. These conditions imply the presence of (even weak) magnetic anisotropy and a macroscopic number of spins in the sublattice. 相似文献
988.
Microstructure and oxygen stoichiometry of YBaCuO films manufactured by laser ablation are investigated. Dependence of the specific electrical resistivity and superconducting
parameters of films on microstructure and oxygen stoichiometry is demonstrated. Conditions of deposition are determined, under
which films with minimum microstructure defects and good conducting properties are formed.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 41–45, February, 2007. 相似文献
989.
The growth mechanism of the peritectic η phase involving the peritectic reaction and peritectic transformation in Cu-70%Sn alloy was investigated under directional
solidification. The results show that a major growth mechanism in thickening of the peritectic η-layer is not the peritectic reaction but the peritectic transformation. The transformation temperature and isothermal time
play crucial roles in determining the volume fraction and the thickness of the peritectic η phase. With the increase of the temperature and isothermal time, the volume fraction of the peritectic η phase increases. The regressed data show that the relationship between the thickness of η phase (Δx) and the transformation temperature (T) meets the following equation In Δx=6.5−1673 1 / T. Additionally, there exists a relationship between the thickness of the η phase (Δx) and the isothermal time (t) at the 9 mm solidification distance below the peritectic reaction interface, Δx=0.72t
1/2, which is consistent with the theoretical model.
Supported by the National Science Foundation of China (Grant No. 50395102) 相似文献
990.
The use of liquid fuels such as kerosene is of interest for the pulse detonation engine (PDE). Within this context, the aim
of this work, which is a preliminary study, was to show the feasibility to initiate a detonation in air with liquid-fuel pyrolysis
products, using energies and dimensions of test facility similars to those of PDEs. Therefore, two liquids fuels have been
compared, JP10, which is a synthesis fuel generally used in the field of missile applications, and decane, which is one of
the major components of standard kerosenes (F-34, Jet A1, ...). The thermal degradation of these fuels was studied with two
pyrolysis processes, a batch reactor and a flow reactor. The temperatures varied from 600°C to 1,000°C and residence times
for the batch reactor and the flow reactor were, respectively, between 10–30 s and 0.1–2 s. Subsequently, the detonability
of synthetic gaseous mixtures, which was a schematisation of the decomposition state after the pyrolysis process, has been
studied. The detonability study, regarding nitrogen dilution and equivalence ratio, was investigated in a 50 mm-diameter,
2.5 m-long detonation tube. These dimensions are compatible with applications in the aircraft industry and, more particularly,
in PDEs. Therefore, JP10 and decane were compared to choose the best candidate for liquid-fuel PDE studies.
This paper was based on work that was presented at the 20th International Colloquium on the Dynamics of Explosions and Reactive
Systems, Montreal, Canada, July 31 – August 5, 2005. 相似文献