全文获取类型
收费全文 | 260篇 |
免费 | 3篇 |
国内免费 | 37篇 |
专业分类
化学 | 127篇 |
晶体学 | 3篇 |
力学 | 5篇 |
综合类 | 1篇 |
数学 | 2篇 |
物理学 | 162篇 |
出版年
2023年 | 11篇 |
2022年 | 8篇 |
2021年 | 6篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 9篇 |
2017年 | 4篇 |
2016年 | 5篇 |
2015年 | 8篇 |
2014年 | 9篇 |
2013年 | 12篇 |
2012年 | 10篇 |
2011年 | 14篇 |
2010年 | 10篇 |
2009年 | 17篇 |
2008年 | 11篇 |
2007年 | 17篇 |
2006年 | 21篇 |
2005年 | 15篇 |
2004年 | 9篇 |
2003年 | 10篇 |
2002年 | 9篇 |
2001年 | 14篇 |
2000年 | 9篇 |
1999年 | 9篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1985年 | 1篇 |
排序方式: 共有300条查询结果,搜索用时 13 毫秒
51.
52.
柱前衍生—反相高效液相色谱法测定钢铁及合金中铌 总被引:1,自引:0,他引:1
建立了反相液相色谱法测定钢铁及合金中铌的分析方法。采用HNO3 HF H2 SO4 溶解样品 ,用酒石酸络合铌 ,以 2 (5 溴 2 吡啶偶氮 ) 5 二乙基氨基酚为柱前衍生试剂 ,在C18柱上用甲醇 水 (体积比为 5 6∶4 4 )为流动相 ,其中含 0 .0 1mol·L- 1pH为 3.5的HOAc NaOAc缓冲液。在60 0nm处测定了铌的配合物 ,方法检出限为 1.5 μg·g- 1。应用此法直接测定了合金铸铁和中低合金钢样品中铌 ,其加标回收率为 96.8%~ 10 3.2 % 相似文献
53.
54.
9-(3,5-二溴)水杨基荧光酮-溴化十六烷基三甲铵荧光光度法测定微量铝 总被引:4,自引:0,他引:4
研究了9-(3,5-二溴)水杨基荧光酮与铝(Ⅲ)的反应条件。在PH5.5的(CH2)6N4-HCL缓冲溶液中,AI(Ⅲ)与试睡成络合物使试剂的荧光猝灭。建立了铝-9-(3,5-二溴),水杨基荧光酮体系测定痕量铝的荧光光度法。荧光强度与铝的含量在0~1.4μg/mL范围内呈线性关系。本法已用于合金风标样中铝的测定。 相似文献
55.
ICP-AES 法测定 RZnAl5RE 合金中的镧、铈、铁、铝、铅、镉 总被引:3,自引:2,他引:1
采用ICP-AES测定了RZnAl5RE合金中的La、Ce、F3、Al、Pb、CD元素含量。考察了基体及无机酸浓度对6种元素线强度的影响。选择了仪器工作条件,检出限在0.03~1.00μg/L之间,加标回收率为93%~108%,相对标准偏差小于12.68%(n=10)。 相似文献
56.
All geometry structures of (CoMn)n (n=1-5) clusters were optimized, and the energy, frequence and magnetism of (CoMn)n (n=1-5) clusters were calculated by using the local spin density approximation and generalized gradient approximation of density functional theory. The same ground state structures of CoMn alloy clusters were confirmed in two methods, and magnetism of CoMn alloy ground state clusters was studied systemically. In order to understand structure and magnetism of CoMn alloy clusters better, Co2n (n=1-5) and Mn2n (n=1-5) clusters were calculated by the same method as alloy clusters, whose ground state structure and magnetism were confirmed. Moreover, the ground state structure and magnetism of clusters with the corresponding CoMn alloy clusters was compared. Results indicated that for (CoMn)n (n=1-4) clusters, geometry structures of CoMn alloy clusters are the same as the corresponding pure clusters still, (CoMn)3 and (CoMn)4 exhibit magnetic bistability, show ferromagnetic and anti-ferromagnetic coupling, local magnetic moment of Co, Mn atoms in CoMn alloy clusters almost preserves magnetism of pure clusters still. 相似文献
57.
利用密度泛函理论(DFT)研究了M12Ni(M=Pt, Sn, Cu) 3种双金属合金团簇的电子活性和结构稳定性, 并探讨了甲烷干法重整反应(DRM)在M12Ni双金属团簇表面的反应能量变化情况. 经比较发现甲烷脱氢和二氧化碳活化过程在Pt12Ni团簇表面进行需克服的活化能垒最低, 反应最易进行. Sn12Ni团簇上生成碳需要较高的活化能, 说明Sn12Ni团簇能够有效抑制焦碳的生成, 一定程度上克服了碳沉积导致的催化剂失活现象, 并且Sn12Ni团簇在C *和CH *氧化过程中表现出最佳的催化活性. Cu12Ni团簇仅在甲烷脱氢过程中表现出较为优异的催化活性. 相似文献
58.
Guillermo Bozzolo Jorge E. Garcs Ronald D. Noebe Phillip Abel Hugo O. Mosca 《Progress in Surface Science》2003,73(4-8):79-116
The BFS method for alloys is applied to the study of the Cu–Pd system. A variety of issues are analyzed and discussed, including the properties of pure Cu or Pd crystals (surface energies, surface relaxations), Pd/Cu and Cu/Pd surface alloys, segregation of Pd (or Cu) in Cu (or Pd), concentration dependence of the lattice parameter of the high temperature fcc CuPd solid solution, the formation and properties of low temperature ordered phases, and order–disorder transition temperatures. Emphasis is made on the ability of the method to describe these properties on the basis of a minimum set of BFS universal parameters that uniquely characterize the Cu–Pd system. 相似文献
59.
P. R. Raimann N. S. Hochgatterer C. Korepp K. C. Möller M. Winter H. Schröttner F. Hofer J. O. Besenhard 《Ionics》2006,12(4-5):253-255
This paper introduces a novel in situ method for monitoring electrode reactions in lithium-ion batteries parallel to the electrochemical experiment (in situ electrochemical environmental scanning electron microscopy). Alloy and alloy/carbon composite electrodes suffer from large volume changes followed by cracking and loss of electronic contact of the particles. The measurement setup and the cell principle are described. Reactions occurring on the surface of a Sn/carbon/binder composite electrode during the lithiation process are presented for illustration. The new method provides insight into the dynamics of electrode reactions, shape changes of particles, spatial distribution of solid electrolyte interphase reactions, etc. 相似文献
60.
S.B. Healy A. Lindsay E.P. OReilly 《Physica E: Low-dimensional Systems and Nanostructures》2006,32(1-2):249
We use a modified band-anticrossing (BAC) model to investigate the band dispersion in a GaNxAs1-x/AlGaAs quantum well (QW) as a function of hydrostatic pressure. The band edge mass increases considerably more quickly with pressure than in the case of a GaAs/AlGaAs QW, and the subband separation also decreases significantly. We predict that the strong anticrossing interaction between the GaAs host conduction band and isolated N levels will inhibit tunnelling through the QW for a range of energy above the isolated N levels. The energy of N resonant states depends strongly on details of the local environment, giving a broader calculated distribution of N states in GaInNAs compared to GaNAs. 相似文献