全文获取类型
收费全文 | 29345篇 |
免费 | 4228篇 |
国内免费 | 3468篇 |
专业分类
化学 | 18479篇 |
晶体学 | 705篇 |
力学 | 1646篇 |
综合类 | 164篇 |
数学 | 1527篇 |
物理学 | 14520篇 |
出版年
2024年 | 87篇 |
2023年 | 346篇 |
2022年 | 777篇 |
2021年 | 873篇 |
2020年 | 1111篇 |
2019年 | 855篇 |
2018年 | 832篇 |
2017年 | 916篇 |
2016年 | 1202篇 |
2015年 | 960篇 |
2014年 | 1324篇 |
2013年 | 2413篇 |
2012年 | 1766篇 |
2011年 | 1829篇 |
2010年 | 1607篇 |
2009年 | 1938篇 |
2008年 | 1960篇 |
2007年 | 2162篇 |
2006年 | 2059篇 |
2005年 | 1572篇 |
2004年 | 1456篇 |
2003年 | 1266篇 |
2002年 | 1016篇 |
2001年 | 844篇 |
2000年 | 801篇 |
1999年 | 706篇 |
1998年 | 647篇 |
1997年 | 508篇 |
1996年 | 509篇 |
1995年 | 447篇 |
1994年 | 408篇 |
1993年 | 316篇 |
1992年 | 248篇 |
1991年 | 221篇 |
1990年 | 167篇 |
1989年 | 134篇 |
1988年 | 119篇 |
1987年 | 89篇 |
1986年 | 94篇 |
1985年 | 95篇 |
1984年 | 70篇 |
1983年 | 29篇 |
1982年 | 45篇 |
1981年 | 47篇 |
1980年 | 34篇 |
1979年 | 33篇 |
1978年 | 13篇 |
1977年 | 24篇 |
1976年 | 14篇 |
1974年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
We show that, contrary to earlier reports, application of the one-parameter variational technique to the classical (image) model for H in front of an Al surface leads to energy shifts for the ground state which are very close to those obtained numerically with a more sophisticated model of the system. 相似文献
92.
L. A. Sakhnovich 《Functional Analysis and Its Applications》2002,36(3):205-211
The conjecture according to which the mean energy of an equilibrium system in quantum theory exceeds the mean energy of the corresponding classical system is considered. It is rigorously proved that the conjecture holds for the potential well. The estimates for the mean energy of the potential well at high and low temperatures are of special interest. 相似文献
93.
W. Kockelmann M. Hofmann O. Moze S.J. Kennedy K.H.J. Buschow 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(1):25-32
The element distributions and the magnetic ordering behaviour of compounds RNi10Si2 (R
=
Tb, Dy, Ho, Er, Tm) have been studied by neutron powder diffraction down to temperatures of 1.6 K. The compounds crystallize
in an ordered variant of the ThMn12 structure type in the tetragonal space group P4/nmm. An ordered 1:1 distribution of Ni and Si on sites 4d and 4e, respectively,
corresponds to a modulation vector [0, 0, 1] with respect to the space group I4/mmm of the ThMn12 structure. TbNi10Si2 orders antiferromagnetically below T
N
= 4.5 K with a magnetic propagation vector of [0, 0, 1/2]. The magnetic Tb moments, 8.97(2) /Tb atom at 1.6 K, are aligned along the c-axis. The Ni sites in TbNi10Si2 do not carry any ordered magnetic moments. The compounds with R
=
Dy, Ho, Er, and Tm are paramagnetic down to 1.6 K and 3.0 K, respectively.
Received 10 July 2002 / Received in final form 12 September 2002 Published online 29 October 2002 相似文献
94.
Ralf Jäger Anatolij I. Saprykin J. Sabine Becker Hans -Joachim Dietze José A. C. Broekaert 《Mikrochimica acta》1997,125(1-4):41-44
The analytical capabilities of a high-resolution mass spectrometer in combination with a 13.56 MHz glow discharge ion source for the analysis of semiconducting materials (silicon carbide and gallium arsenide) were studied. It was shown that single positively charged ions of sample material have about 10 eV higher average energy than the ions of the discharge and residual gas. Therefore effective energy separation of the ions of analyte from the ions of the discharge and residual gas was achieved by adjusting the ion transfer optics (breadth and position of energy slit), which improves the analytical capabilities of the developed method.Some analytical applications are presented to illustrate the performance of r.f. GDMS for the bulk analysis of semiconducting materials. The results of the trace element analysis of gallium arsenide and silicon carbide samples are compared with data of independent methods (LIMS, ICP-AES, SIMS).Dedicated to Professor Dr. rer. nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthdayOn leave from the Institute of Inorganic Chemistry, 630090 Novosibirsk, Russia 相似文献
95.
谐振子薛定谔方程的简单解法 总被引:2,自引:0,他引:2
物质的许多物理与化学性质都可以用线性谐振子模型解释,本文用简单的数学运算求解线性谐振子的薛定谔方程,避免了特殊函数等复杂的数学运算,得出了量子力学教材完全相同的结果。 相似文献
96.
M. U. Belyi N. E. Bartnitskaya I. F. Mel'nik B. A. Okhrimenko S. M. Yablochkov 《Journal of Applied Spectroscopy》1995,62(3):564-567
T. Shevchenko Kiev University, 252022 Kiev, Pr. Akad. Glushakova, 6, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 62, No. 3, pp. 192–196, May–June, 1995. 相似文献
97.
Vasily L. Morgunov 《Pramana》2007,69(6):1097-1100
A new calorimeter energy calibration method was developed for the proposed ILC detectors. The method uses the center-of-mass
energy of the accelerator as the reference. It has been shown that using the energy conservation law it is possible to make
ECAL and HCAL cross calibration to reach a good energy resolution for the simple calorimeter energy sum.
相似文献
98.
In this work two non-local problems for the parabolic-hyperbolic type equation with non-characteristic line of changing type
are considered. Unique solvability of these problems is proven. The uniqueness of the solution is proven by the method of
energy integrals and the existence is proven by the method of integral equations. 相似文献
99.
The direct growth of ZnSe–CdSe solid solution onto metallic cathodes by electrodeposition from acidic aqueous sulphate solutions
is described. The plating process is studied by simple voltammetry, while the structure and composition of the electrolytic
deposits are investigated by X-ray diffraction. The experimental d-spacing values of the as-grown mixed lattice are compared to data from reference Zn
x
Cd1-x
Se pellets of standard composition, produced by a sintering method. The findings are supplemented with energy-dispersive X-ray
(EDX) elemental analysis. Thereupon, the variation of the mole fraction x in Zn
x
Cd1-x
Se, and the solid phase constitution of the electrodeposits are determined and correlated to the electrochemical conditions
of growth. The resulting films contain admixtures of CdSe compound and metallic Cd. 相似文献
100.
LUO You-Hua GE Zi-Ming 《理论物理通讯》2006,46(12)
In noncommutative space, we examine the problem of a noninteracting and harmonically trapped BoseEinstein condensate, and derive a simple analytic expression for the effect of spatial noncommutativity on energy spectrum of the condensate. It indicates that the ground-state energy incorporating the spatial noncommutativity is reduced to a lower level, which depends upon the noncommutativity parameter θ. The gap between the noncommutative space and commutative one for the ground-state level of the condensate should be a signal of spatial noncommutativity. 相似文献