首页 | 官方网站   微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   29篇
  免费   48篇
  国内免费   34篇
数理化   111篇
  2017年   5篇
  2014年   2篇
  2013年   1篇
  2012年   1篇
  2009年   6篇
  2008年   7篇
  2007年   16篇
  2006年   12篇
  2005年   11篇
  2004年   8篇
  2003年   9篇
  2002年   5篇
  2001年   2篇
  2000年   5篇
  1999年   1篇
  1998年   3篇
  1997年   3篇
  1996年   1篇
  1995年   1篇
  1994年   3篇
  1993年   1篇
  1992年   4篇
  1991年   1篇
  1989年   1篇
  1985年   1篇
  1982年   1篇
排序方式: 共有111条查询结果,搜索用时 0 毫秒
31.
稀土材料红外多光子量子剪裁现象   总被引:1,自引:0,他引:1  
稀土红外量子剪裁为目前国内外的研究热点,它对于提高太阳能电池的效率从而减低太阳能发电的造价很有意义。论文综述了稀土红外量子剪裁的研究意义,在总结了太阳能电池发电和损耗的原理的基础上,分析了稀土红外量子剪裁提高太阳能电池效率的具体途径。同时综述了单掺Er3+材料的稀土红外量子剪裁发光现象:光激发2H11/2能级有很强的4I13/2→4I15/2红外量子剪裁发光,速率很大的{2H11/2→4I9/2,4I15/2→4I13/2}交叉能量传递为导致光激发2H11/2能级有高量子剪裁效率的主要原因。  相似文献   
32.
The fragmentation cross sections of reactions ^12C+^2H, ^12C, ^14N, ^16O at beam energies from 50 to 100 MeV/nucleon are investigated using the isospin-dependent Boltzmann-Langevin equation model. It is found that fragment species increase approximately with the increasing target mass. The fragment species and some fragments production cross sections in reactions of ^12C+^12C, ^14N, ^16O show an obvious variation at the beam energies from 50 to 80 MeV/nucleon. However the calculated fragment production cross sections do not change much when the incident energy increases from 80 to 100 MeV/nucleon.  相似文献   
33.
精确测量了32S+90,96Zr两系统的背角准弹散射激发函数, 总体误差小于1%, 从中分别抽取了它们的势垒分布, 对比观测到32S+96Zr的势垒结构扁平且向低能区展宽, 这种 势垒可导致在垒下能区该体系的熔合截面的大大增强. 32S+96Zr与32S+90Zr相比 存在较强的中子转移反应, 且转移Q值为正. 32S+96Zr势垒的扁平结构可能是中子转移道耦合所致, 这会导致32S+96Zr垒下熔合截面大的增强.  相似文献   
34.
Elastic scattering angular distributions of the 14^N+16^O system and the angular distributions of transfer reaction 16^O(14^N,13^C)17^F at ELab=76.2 MeV and 57 MeV have been measured and calculated by means of the exact finiterange distorted-wave Born approximation with the PTOLEMY code. The optical potential parameters for the weakly bound nuclear system 17^F+13^C have been deduced and applied to analyse the elastic scattering angular distributions of the similar systems 17^F+12^C and 17^F+14^N which are taken from literature. The result shows that the transfer reaction with stable projectile and target combination can be used as an alternative method to extract the optical potential parameters for the weakly bound nuclear system.  相似文献   
35.
Collisions of a low energy heavy ion with a myoglobin in water are simulated by molecular dynamics model. The increase of total energy is very small. The mean squared fluctuation decreases at 300 K and increases at 250K. This is an important novel cooling effect that protects the protein from ion damage. The possible collision side effect is the change of tertiary structure that blocks the normal functions of the myoglobin.  相似文献   
36.
A general scheme for controlled teleportation of an arbitrary multi-qudit state with d-dimensional Greenberger- Horne--Zeilinger (GHZ) states is proposed. For an arbitrary m-qudit state, the sender Alice performs m generalized Bell-state projective measurements on her 2m qudits and the controllers need only take some single-particle measurements. The receiver Charlie can reconstruct the unknown m-qudit state by performing some single-qudit unitary operations on her particles if she cooperates with all the controllers. As the quantum channel is a sequence of maximally entangled GHZ states, the intrinsic efticiency for qudits in this scheme approaches 100% in principle.  相似文献   
37.
研究了奇质子核Lu和Ta同位素链h11/2质子9/2[514]转动带旋称劈裂的系统规律,并与同一核区奇奇核的πh11/2×vi13/2两准粒子转动带低自旋区旋称劈裂规律进行了比较,指出奇质子Lu和Ta核三准粒子带的旋称反转很可能是来源于h11/2准质子和 i13/2准中子之间的相互作用。The systematic features of signature splitting of the h11/2 9/2 [ 514] rotational band in Lutetium and Tantalum isotope chains have been investigated and compared with that of πh11/2×vi13/2 2-quasiparticle band in oddodd nuclei of the same nuclear region. It is shown that signature inversion of 3-quasiparticle band of some odd- Z Lutetium and Tantalum nuclei most probably caused by the p-n interaction of h11/2 quasiproton and i13/2 quasineutron.  相似文献   
38.
Molecular Dynamics Simulation of the Structure I Empty Gas Hydrate   总被引:1,自引:0,他引:1       下载免费PDF全文
The 368 water molecule structure I empty gas hydrates with three possible hydrogen orientations are calculated using TIP4P potential molecular dynamical simulations.The thermodynamic properties and hydrogen bonding are compared with ice Ih.The density of states is analysed based on experimental measurements.The empty gas hydrate at low temperature is stable without gas molecules encaged.  相似文献   
39.
讨论了超重核形成截面计算中的耦合道效应、壳效应的阻尼效应、能级密度的集体运动增强因子以及蒸发残余核的自旋分布等几个重要问题,并给出相应的实验结果.因这些因素都可能对截面有数量级的影响,正确处理与否直接关系到超重核合成截面理论预言的可靠性. .Several important aspects in the cross section calculations for the synthesis of superheavy nuclei have been inquired. They are the effects of the coupled channels, the damping of shell correction energy, the collective enhancements in the level density and the spin distributions of evaporation residues. The channel coupling of relative motion with internal degrees of freedom will enhance significantly the capture cross section at sub barrier energies. However, recent measurements of spin distributions for ...  相似文献   
40.
刘祖华 《中国物理 C》2000,24(Z1):29-32
分析在稀土核区没有找到巨超形变的物理原因.探讨在锕系核区寻找巨超形变核态的理论依据、实验方法、初步结果和存在问题.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号