全文获取类型
收费全文 | 655630篇 |
免费 | 6274篇 |
国内免费 | 1791篇 |
专业分类
化学 | 334377篇 |
晶体学 | 9133篇 |
力学 | 32452篇 |
综合类 | 22篇 |
数学 | 85956篇 |
物理学 | 201755篇 |
出版年
2021年 | 5845篇 |
2020年 | 6407篇 |
2019年 | 7243篇 |
2018年 | 9631篇 |
2017年 | 9708篇 |
2016年 | 13606篇 |
2015年 | 7653篇 |
2014年 | 12507篇 |
2013年 | 29402篇 |
2012年 | 22845篇 |
2011年 | 27328篇 |
2010年 | 19971篇 |
2009年 | 19740篇 |
2008年 | 25586篇 |
2007年 | 25545篇 |
2006年 | 23444篇 |
2005年 | 21017篇 |
2004年 | 19599篇 |
2003年 | 17623篇 |
2002年 | 17361篇 |
2001年 | 18521篇 |
2000年 | 14445篇 |
1999年 | 11172篇 |
1998年 | 9552篇 |
1997年 | 9397篇 |
1996年 | 8825篇 |
1995年 | 8015篇 |
1994年 | 7885篇 |
1993年 | 7614篇 |
1992年 | 8172篇 |
1991年 | 8591篇 |
1990年 | 8240篇 |
1989年 | 8022篇 |
1988年 | 7929篇 |
1987年 | 7740篇 |
1986年 | 7347篇 |
1985年 | 9390篇 |
1984年 | 9990篇 |
1983年 | 8348篇 |
1982年 | 8734篇 |
1981年 | 8203篇 |
1980年 | 7769篇 |
1979年 | 8262篇 |
1978年 | 8624篇 |
1977年 | 8517篇 |
1976年 | 8538篇 |
1975年 | 8106篇 |
1974年 | 7917篇 |
1973年 | 8329篇 |
1972年 | 5919篇 |
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
991.
992.
A. Sanusi M. Z. A. Yahya S. Navaratnam W. J. Basirun Y. Alias N. S. Mohamed A. K. Arof 《Ionics》2003,9(3-4):253-257
In this study, lead sulphide (PbS) was prepared by the chemical bath deposition technique. The sample was characterized by
X-ray diffraction (XRD), Energy Dispersive Analysis of X-rays (EDAX) and cyclic voltammetry. EDAX spectrum shows peaks attributable
to lead and sulphur. The EDAX analysis also shows that the prepared sample is stoichiometric. Cyclic voltammetry experiments
were recorded at 100 mV·s−1 and 400 mV·s−1 scan rates. Results show that the rate controlling electrochemical reaction is electron transfer. The presence of redox waves
shows that the lithium intercalation and deintercalation can occur as a result of lattice expansion in PbS. There were no
differences in the PbS XRD data before and after the cyclic voltammetry experiments indicating that the PbS structure is not
modified upon lithium ion intercalation and deintercalation in PbS. The discharge characteristics for 35 cycles of the cell
using the LiCoO2/PbS couple is presented indicating the possible development of such materials as anode in lithium ion cells. 相似文献
993.
A. A. Nazarov 《Physics of the Solid State》2003,45(6):1166-1169
A solution to the equation of grain-boundary diffusion is obtained under conditions where migration of the diffusant from the boundaries into the grains is absent and the diffusion coefficient decreases with time from an increased value to a value characteristic of equilibrium grain boundaries. The specific features of the grain-boundary diffusion in nanocrystals are qualitatively analyzed in terms of this solution. 相似文献
994.
V. Bradnova M. M. Chernyavsky L. Just S. P. Kharlamov A. D. Kovalenko M. Haiduc K. A. Kotel’nikov V. A. Krasnov V. G. Larionova F. G. Lepekhin A. I. Malakhov G. I. Orlova N. G. Peresadko N. G. Polukhina P. A. Rukoyatkin V. V. Rusakova N. A. Salmanova B. B. Simonov S. Vokal P. I. Zarubin 《Physics of Atomic Nuclei》2003,66(9):1646-1650
A physical program of irradiation of emulsions in beams of relativistic nuclei named the BECQUEREL Project is reviewed. It is destined to study in detail the processes of relativistic fragmentation of light radioactive and stable nuclei. The expected results would make it possible to answer some topical questions concerning the cluster structure of light nuclei. Owing to the best spatial resolution, the nuclear emulsions would enable one to obtain unique and evident results. The most important irradiations will be performed in the secondary beams of He, Be, B, C, and N radioactive nuclei formed on the basis of JINR Nuclotron beams of stable nuclei. We present results on the charged state topology of relativistic fragmentation of the 10B nucleus at low energy-momentum transfers as the first step of the research. 相似文献
995.
996.
997.
998.
Paulo D. Cordaro 《Advances in Mathematics》2004,184(1):89-118
Taking as a start point the recent article of Meziani [7], we present several results concerning the normalization of a class of complex vector fields in the plane which degenerate along a real curve. We mainly deal with operators with finite regularity and analyze both the local situation as well as the case of normalization near a circle. Some related questions (e.g., on semi-global solvability and on the normalization of a class of generalized Mizohata operators) are also discussed. 相似文献
999.
Blokhina S. V. Bykova V. V. Sharapova A. V. Ol'khovich M. V. Trostin A. N. 《Russian Journal of General Chemistry》2003,73(2):257-259
The sorption properties of stationary phases based on nematic p-substituted azoxybenzenes were studied. Correlations were revealed between the structural selectivity of mesogens, chemical nature of terminal substituents, capability for dispersion interactions and polarity of the sorbents, temperature gradient of the retention indices, and thermodynamic parameters of solution of xylene isomers in the sorbents. 相似文献
1000.
Amorphization of Al32Ge68 at normal pressure, starting from the thermobarically quenched high-pressure crystalline metallic γ-phase, was studied in a slow heating run by performing NMR field-sweep experiments. In the temperature interval from 77 to 300 K the 27Al central line exhibits a continuous broadening and a positive frequency shift. Close to 300 K rather abrupt changes were observed, where the shift changed its sign, and the line width jumped to its highest value. The discontinuous course of the phase changes indicates that the amorphization process proceeds via a sequence of intermediate metastable states, which can be ‘overheated’ in a slow heating run and consequently transform in an explosion-like manner to the final amorphous state at a well-defined temperature. The frequency shift could be decomposed into the negative second-order quadrupolar shift and the positive Knight shift. The change of the shift sign from positive to negative at 300 K reflects the vanishing tendency of the Knight shift upon heating and is compatible with the conduction-electron localization upon structure amorphization. 相似文献