全文获取类型
收费全文 | 357篇 |
免费 | 81篇 |
国内免费 | 134篇 |
专业分类
化学 | 316篇 |
晶体学 | 11篇 |
力学 | 27篇 |
综合类 | 40篇 |
数学 | 36篇 |
物理学 | 142篇 |
出版年
2024年 | 1篇 |
2023年 | 10篇 |
2022年 | 10篇 |
2021年 | 14篇 |
2020年 | 7篇 |
2019年 | 11篇 |
2018年 | 15篇 |
2017年 | 11篇 |
2016年 | 16篇 |
2015年 | 16篇 |
2014年 | 29篇 |
2013年 | 19篇 |
2012年 | 15篇 |
2011年 | 18篇 |
2010年 | 20篇 |
2009年 | 21篇 |
2008年 | 17篇 |
2007年 | 36篇 |
2006年 | 26篇 |
2005年 | 31篇 |
2004年 | 26篇 |
2003年 | 28篇 |
2002年 | 19篇 |
2001年 | 14篇 |
2000年 | 20篇 |
1999年 | 20篇 |
1998年 | 15篇 |
1997年 | 13篇 |
1996年 | 9篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1991年 | 10篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 1篇 |
1984年 | 4篇 |
1982年 | 1篇 |
1979年 | 2篇 |
1965年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有572条查询结果,搜索用时 15 毫秒
71.
72.
数学通报1986年第2期《如何证明动曲线过定点》一文,介绍了两种证明动曲线过定点的方法。笔者感到还有两种方法需要补充,并且该文例3还可以作一些推广。兹介绍如下。 相似文献
73.
本文利用紫胶树脂碱水解后,其链状与环状组份性质的差别,首次从国产紫胶树脂中分离得到一种无色透明的立方晶体,经光谱证实为壳脑酸二甲酯。 相似文献
74.
75.
76.
The difference in temporal structures of retinal ganglion cell spike trains between spontaneous activity and firing activity after contrast adaptation is investigated. The Lempel-Ziv complexity analysis reveals that the complexity of the neural spike train decreases after contrast adaptation. This implies that the behaviour of the neuron becomes ordered, which may carry relevant information about the external stimulus. Thus, during the neuron activity after contrast adaptation, external information could be encoded in forms of some certain patterns in the temporal structure of spike train that is significantly different, compared to that of the spike train during spontaneous activity, although the firing rates in spontaneous activity and firing activity after contrast adaptation are sometime similar. 相似文献
77.
Experimental Study on Electrostatic with Two Guiding of Supersonic D20 Molecular Beam Charged Wires 下载免费PDF全文
We demonstrate the guiding of a supersonic heavy-water (D2O) molecular beam using a hollow electrostatic field generated by the combination of two parallel charged-wires and two grounded metal-plates, and report some new and preliminary experimental results. In the experiment, we detect the guiding signals by using the method of time-of-flight mass spectrum and study the dependence of the relative transmission of the beam guide on the guiding voltage. Our study shows that the relative transmission of the beam guide is increased linearly with increasing guiding voltage Vguid, and the number of the guided D20 molecules is at least increased by 89.4% when the guiding voltage is +20.0k V. Finally, some potential applications of our guiding scheme in the molecule optics are briefly discussed. 相似文献
78.
We have calculated the ground-state energy of the symmetric quantum-dot pattern by the ab initio calculation method, i.e. unrestricted Hartree-Fock-Roothaan (UHFR) method based on the Gaussian basis, and studied their electric capacitance spectra, assuming each quantum dot of quantum-dot pattern to be confined in a three-dimensional spherical potential well of finite depth. For the systems in question, our results show that our method and theoretical model not only give the electric capacitance peaks similar to s-shell and p-shell atom-like quantum dot, but also show some new fine-structure of electric capacitance in the symmetric quantum-dot pattern system. This method might be a feasible tool to study few-electron problems on the symmetric quantum-dot pattern system. 相似文献
79.
80.