全文获取类型
收费全文 | 251999篇 |
免费 | 1583篇 |
国内免费 | 402篇 |
专业分类
化学 | 115477篇 |
晶体学 | 3469篇 |
力学 | 13582篇 |
综合类 | 7篇 |
数学 | 39714篇 |
物理学 | 81735篇 |
出版年
2019年 | 1172篇 |
2018年 | 10432篇 |
2017年 | 11288篇 |
2016年 | 6591篇 |
2015年 | 2423篇 |
2014年 | 2540篇 |
2013年 | 6437篇 |
2012年 | 9317篇 |
2011年 | 18806篇 |
2010年 | 11516篇 |
2009年 | 11635篇 |
2008年 | 16451篇 |
2007年 | 20079篇 |
2006年 | 5604篇 |
2005年 | 11978篇 |
2004年 | 7911篇 |
2003年 | 7319篇 |
2002年 | 5320篇 |
2001年 | 4492篇 |
2000年 | 3630篇 |
1999年 | 2615篇 |
1998年 | 2285篇 |
1997年 | 2205篇 |
1996年 | 2156篇 |
1995年 | 2002篇 |
1994年 | 1974篇 |
1993年 | 1804篇 |
1992年 | 2065篇 |
1991年 | 2197篇 |
1990年 | 1994篇 |
1989年 | 2003篇 |
1988年 | 1949篇 |
1987年 | 1848篇 |
1986年 | 1773篇 |
1985年 | 2285篇 |
1984年 | 2430篇 |
1983年 | 1994篇 |
1982年 | 2167篇 |
1981年 | 2056篇 |
1980年 | 1979篇 |
1979年 | 2136篇 |
1978年 | 2314篇 |
1977年 | 2098篇 |
1976年 | 2182篇 |
1975年 | 2072篇 |
1974年 | 2121篇 |
1973年 | 2156篇 |
1972年 | 1392篇 |
1971年 | 1235篇 |
1968年 | 1177篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
891.
892.
893.
V. A. Reznikov 《Technical Physics》2003,48(9):1216-1218
A shell model that describes the formation of molecular complexes around a C60 molecule upon the solid-phase interaction of the powders is considered. From the absorption spectra, it follows that a reacting
particle is a fullerene dimer. 相似文献
894.
T. M. Shneidman G. G. Adamian N. V. Antonenko S. P. Ivanova R. V. Jolos W. Scheid 《Physics of Atomic Nuclei》2003,66(2):206-217
Based on the dinuclear system concept, the role of bending vibrations in creation of the angular momentum of primary fission fragments is investigated. For 252Cf spontaneous fission, the angular momenta of the fragments are calculated as a function of the neutron multiplicity and compared with available experimental data. Different cluster compositions of the 252Cf fission modes at the scission point are considered. 相似文献
895.
R. Weidmann 《Archiv der Mathematik》2003,81(5):589-595
We describe a family of graph manifolds that have 2-generated
fundamental group but do not admit a Heegaard splitting of genus 2. They are
closely related to the examples provided by Boileau and Zieschang if these are
considered as (non-proper) graph manifolds.Received: 14 August 2002 相似文献
896.
Lasing and discharge in mixtures of SF6 with hydrogen and hydrocarbons are investigated. If the chemical reaction is initiated by a self-sustained discharge (a generator
with both an inductive and capacitive energy storage can be used), the maximum lasing efficiency is attained at high values
of the ratio E/p (where E is the electric field intensity and p is the pressure in the mixture) if shaped electrodes and preionization of the discharge gap are employed. For the first time,
the lasing efficiency obtained in a nonchain HF laser is as high as 10% of the energy deposit and 4.5% of the stored energy
for a specific radiation energy of ≈140 J/(l atm). At high efficiencies, the emission spectrum of the nonchain HF laser significantly
broadens and cascade lasing at P(3-2) → P(2-1) → P(1-0) vibrational transitions for several rotational lines is realized. 相似文献
897.
R. M. Sardarly O. A. Samedov I. Sh. Sadykhov V. A. Aliev 《Physics of the Solid State》2003,45(6):1118-1121
The relaxor properties of Fe-doped TlInS2 crystals are investigated. It is shown that Fe-doped TlInS2 compounds exhibit all features inherent in relaxor ferroelectric materials. The temperature range of existence of the microdomain (relaxor) state and the temperature of the transition from this state to a macro-domain state are determined. 相似文献
898.
899.
Terminal alkynes undergo mild and efficient aminomethylation with aqueous formaldehyde and secondary amines under CuI catalysis. In most cases high to nearly quantitative yields of tertiary propargylamines are obtained in DMSO solution at room temperature. Aromatic, aliphatic and silylated acetylenes as well as alkynols can be used. Primary amines are less reactive and satisfactory yields of secondary propargylamines are obtained only with phenylacetylene. 相似文献
900.
V. L. Tsymbalenko 《JETP Letters》2003,78(8):493-496
The kinetics of formation of an anomalous phase from a solution with a small 3He impurity was studied in the temperature range 0.2–0.7 K up to a supersaturation of ~30 mbar. The phase diagram was determined for normal and anomalous growths. It is found that, in the presence of impurities, the formation of a fast-growing state is retarded. This experimental fact indicates that the dissipative processes in fluids have an appreciable effect on the phase formation kinetics. The retardation is, possibly, caused by the direct interaction of an impurity with the crystal surface. 相似文献