全文获取类型
收费全文 | 389305篇 |
免费 | 13389篇 |
国内免费 | 7452篇 |
专业分类
化学 | 206039篇 |
晶体学 | 4886篇 |
力学 | 19802篇 |
综合类 | 522篇 |
数学 | 46582篇 |
物理学 | 132315篇 |
出版年
2022年 | 2998篇 |
2021年 | 5017篇 |
2020年 | 5768篇 |
2019年 | 6116篇 |
2018年 | 7285篇 |
2017年 | 7289篇 |
2016年 | 10182篇 |
2015年 | 7042篇 |
2014年 | 10475篇 |
2013年 | 20476篇 |
2012年 | 17959篇 |
2011年 | 20602篇 |
2010年 | 14945篇 |
2009年 | 14764篇 |
2008年 | 17191篇 |
2007年 | 16760篇 |
2006年 | 15447篇 |
2005年 | 13384篇 |
2004年 | 12113篇 |
2003年 | 10436篇 |
2002年 | 10221篇 |
2001年 | 11703篇 |
2000年 | 8503篇 |
1999年 | 6946篇 |
1998年 | 5858篇 |
1997年 | 5584篇 |
1996年 | 5277篇 |
1995年 | 4778篇 |
1994年 | 4689篇 |
1993年 | 4438篇 |
1992年 | 4724篇 |
1991年 | 4854篇 |
1990年 | 4527篇 |
1989年 | 4361篇 |
1988年 | 4036篇 |
1987年 | 4178篇 |
1986年 | 3895篇 |
1985年 | 4842篇 |
1984年 | 4798篇 |
1983年 | 3980篇 |
1982年 | 4034篇 |
1981年 | 3735篇 |
1980年 | 3662篇 |
1979年 | 3916篇 |
1978年 | 3900篇 |
1977年 | 3920篇 |
1976年 | 3900篇 |
1975年 | 3681篇 |
1974年 | 3623篇 |
1973年 | 3667篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
Recent success in strain engineering has triggered tremendous interest in its study and potential applications in nanodevice design. In this paper, we establish a coupled piezoelectric/semiconducting model for a wurtzite structure ZnO nanofiber under the local mechanical loading. The energy band structure tuned by the local mechanical loading and local length is calculated via an eight-band k·p method, which includes the coupling of valance and conduction bands. Poisson's effect on the distribution of electric potential inversely depends on the local mechanical loading. Numerical results reveal that both the applied local mechanical loading and the local length exhibit obvious tuning effects on the electric potential and energy band. The band gap at band edges varies linearly with the applied loading. Changing the local length shifts the energy band which is far away from the band edges. This study will be useful in the electronic and optical enhancement of semiconductor devices. 相似文献
53.
A model with 16 moments is here presented in the framework of RET of polyatomic gases. It furnishes as principal subsystem the relativistic counterpart of a work by Arima T., Ruggeri T., Sugiyama M.; this is present in literature and treats the non relativistic case which incorporates relaxation processes of molecular rotation and vibration. Another principal subsystem is the natural extension of the 14 moments model by Pennisi S. and Ruggeri T.; this is also present in literature in the relativistic framework but where the trace of the third balance equation is neglected. Its extension is found here for the case when this trace isn’t neglected.
相似文献54.
Siberian Mathematical Journal - Some structural properties are discussed of the functions in $ P_{2}\times P_{2} $ . We describe the properties of functions not belonging to the maximal... 相似文献
55.
Kuzmenkova P. S. Gromushkin D. M. Shulzhenko I. A. Tretyakova T. D. 《Physics of Atomic Nuclei》2021,84(9):1588-1592
Physics of Atomic Nuclei - The paper presents a comparison of three neutrons identifying methods in scintillators based on ZnS with 6Li and 10B: charge integration method, pulse gradient analysis,... 相似文献
56.
Novikov V. S. Kuznetsov S. M. Kuzmin V. V. Prokhorov K. A. Sagitova E. A. Darvin M. E. Lademann J. Ustynyuk L. Yu. Nikolaeva G. Yu. 《Doklady Physics》2021,66(9):257-263
Doklady Physics - The dependence of Raman spectra of the molecules containing polyene chains on the conjugation length, structure of side and end groups, and isomer type is analyzed theoretically. 相似文献
57.
Physics of Atomic Nuclei - In this paper, the analysis of the relation between the multiplication factor of neutrons of the multiplying system measured in critical experiments and the system... 相似文献
58.
59.
Mathematical Notes - We consider the problem of maximization of an integral functional on the space of increasing functions, which is motivated by economic concerns for tax mechanisms optimization.... 相似文献
60.
Differential Equations - We study a linear integro-differential equation with a singular differential operator in the leading part. A special generalized version of the collocation method is... 相似文献