全文获取类型
收费全文 | 104篇 |
免费 | 26篇 |
国内免费 | 46篇 |
专业分类
化学 | 27篇 |
力学 | 2篇 |
数学 | 2篇 |
物理学 | 145篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 2篇 |
2014年 | 6篇 |
2013年 | 10篇 |
2012年 | 5篇 |
2011年 | 9篇 |
2010年 | 2篇 |
2009年 | 14篇 |
2008年 | 9篇 |
2007年 | 5篇 |
2006年 | 7篇 |
2005年 | 11篇 |
2004年 | 8篇 |
2003年 | 15篇 |
2002年 | 8篇 |
2001年 | 17篇 |
2000年 | 11篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有176条查询结果,搜索用时 15 毫秒
81.
昵博铜镍多金属矿位于滇东南地区,大地构造位置属于特提斯―喜马拉雅构造域和环太平洋构造域的交接部位。该区域土壤次生晕测量结果表明,Cu、Fe、Ti、Co、Ni、Cr、V元素背景含量较高,Au、As、Sb、Hg元素背景含量偏低,Au可能来自深源,其分布与反应基性、超基性岩的元素相似。结合矿区地质背景分析并进一步处理土壤次生晕数据,确定区域地球化学背景、元素富集区域及化学异常带,结合地质背景,共划分出两处化学异常带为成矿有利区域,其找矿前景良好。测量数据可为今后进一步的勘查工作提供可靠依据。 相似文献
82.
叶沿林 庞丹阳 葛愉成 江栋兴 郑涛 王全进 李智焕 李湘庆 艾颖 张高龙 王佳 陈志强 胡青元 A.Ozawa Y.Yamaguchi C.Wu R.Kanungo D.Fang I.Tanihata 《原子核物理评论》2005,22(1):1-2
实验测量了25 MeV/u 的6He+9Be反应中的单、双中子转移微分截面. 利用反应耦合道模型初步分析了实验数据, 计算大体重现截面值. 转移反应对末态有相当的选择性, 并且双中子转移截面主要来自到基态的一步过程. 后角度截面的上升可能与连续态的耦合有关. Differential cross sections for quasi elastic scattering at forward angles and for 1n and 2n transfer reaction at backward angles induced by 6He at 25 MeV/u from 9Be target were measured. The experimental data were analyzed in the framework of the CRC model. The raise at backward angle of the 1n and 2n transfer cross section can not reproduced by the current calculation. 相似文献
83.
Bhattacharyya A. B. Huit Banerjee Shibaji Ghosh Sanjay K. Raha Sibaji Sinha Bikash Toki Hiroshi 《Pramana》2003,60(5):909-919
A first-order quark hadron phase transition in the early Universe may lead to the formation of quark nuggets. The baryon number
distribution of these quark nuggets have been calculated and it has been found that there are sizeable number of quark nuggets
in the stable sector. The nuggets can clump and form bigger objects in the mass range of 0.0003M⊙ to 0.12M⊙. It has been discussed
that these bigger objects can be possible candidates for cold dark matter. 相似文献
84.
发展了BUU模型,能够同时研究双中子晕结构核11Li引起反应的核反应总截面和双中子剥去截面,计算中使用软的核物质状态方程和0.8倍的核子–核子碰撞截面,同时还用相对论平均场模型计算的中子和质子密度代替通常使用的方密度分布,计算结果可以很好地拟合不同反应系统的实验数据,假定对于晕核及其核芯核,彼此的核反应总截面与相互作用截面之间的差别相同,那么11Li的双中子剥去截面可以表示成”Li及其核芯核9Li引起反应的核反应总截面之差,研究结果表明这一假定可以适用于高能,对于中能核反应需要更多的实验数据来检验. 相似文献
85.
吕林辉 叶沿林 江栋兴 华辉 郑涛 李智焕 葛愉成 李湘庆 楼建玲 曹中鑫 宋玉收 肖军 李奇特 乔锐 游海波 陈瑞久 徐瑚珊 王建松 郭忠言 张雪荧 李琛 胡正国 陈若富 王猛 徐治国 岳珂 唐彬 臧永东 章学恒 姚向武 陈金达 白真 《中国物理 C》2011,35(10):891-895
A knockout reaction induced by 6He at 61.2 MeV/u was carried out at the HIRFL-RIBLL radioactive beam line. The α core fragments at forward angles were detected in coincidence with the recoiled protons at large angles. From this coincident measurement the valence nucleon knockout mechanism and the core knockout mechanism can be separated according to the polar angle correlation between the core fragments and the recoiled protons. It is demonstrated that, when reconstructing the resonant state of a weakly bound nucleus, the contamination resulting from the core knockout mechanism should be eliminated in order to obtain the correct structure information. 相似文献
86.
The structure of Ne isotopes has been investigated by using deformed Skyrme-Hartree-Fock (SHF) method and BCS approximation. Especially the effect of tensor force on the halo structure of 29Ne and 31Ne is discussed. To this end, the tensor contributions are considered to the energy density function and the single particle potential in SHF theory. For comparison, four Skyrme interactions are used: SLy5 and SGII without tensor force, and SLy5+T and SGII+ T with tensor force. The results indicate that the inclusion of tensor force shows a more pronounced halo structure for 31Ne. 相似文献
87.
The coordinate-space Hartree-Fock-Bogoliubov(HFB) approach with quasiparticle blocking has been applied to study the odd-A weakly bound nuclei ~(17,19)B and ~(37)Mg,in which halo structures have been reported in experiments.The Skyrme nuclear forces SLy4 and UNEDF1 have been adopted in our calculations.The results with and without blocking have been compared to demonstrate the emergence of deformed halo structures due to blocking effects.In our calculations,~(19)B and ~(37)Mg have remarkable features of deformed halos. 相似文献
88.
Uncertainty evaluation of the isotope shift factors for 2s2p~(3,1)P_1~o–2s~2 ~1S_0 transitions in B Ⅱ 下载免费PDF全文
Accurate isotope shift factors of the 2s2p~(3,1)P_1~o–2s~2 ~1S_0 transitions in B II, obtained with the multi-configuration Dirac–Hartree–Fock and the relativistic configuration interaction methods, are reported. We found a linear correlation relation between the mass shift factors and the energies for the transitions concerned, considering all-order electron correlations. This relation is important for estimating the uncertainty in the calculation of isotope shift factors. These atomic data can be used to extract the nuclear mean-square charge radii of the boron isotopes with halo structures or to resolve the high precise spectroscopy of B II in astronomical observation. 相似文献
89.
通过建立晕电流峰值分布的高斯混合模型,结合靶板结构的极限状态方程,利用Monte Carlo 方法开展了晕电流作用下EAST 上偏滤器靶板的可靠性研究。研究结果表明,在晕电流作用下,EAST 上偏滤器靶板具有极高的可靠性。这一结果为EAST 上偏滤器以及CFETR 的可靠性研究提供了参考。 相似文献
90.
David L. Canham H. -W. Hammer 《The European Physical Journal A - Hadrons and Nuclei》2008,37(3):367-380
The universal properties and structure of halo nuclei composed of two neutrons (2n) and a core are investigated within an effective quantum mechanics framework. We construct an effective interaction potential
that exploits the separation of scales in halo nuclei and treat the nucleus as an effective three-body system. The uncertainty
from higher orders in the expansion is quantified through theoretical error bands. First, we investigate the possibility to
observe excited Efimov states in 2n halo nuclei. Based on the experimental data, 20C is the only halo nucleus candidate to possibly have an Efimov excited state, with an energy less than 7 keV below the scattering
threshold. Second, we study the structure of 20C and other 2n halo nuclei. In particular, we calculate their matter form factors, radii, and two-neutron opening angles. 相似文献