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121.
The formation of fragments in proton-induced reactions at low relativistic energies within a combination of a covariant dynamical transport model and a statistical approach is investigated. In particular, we discuss in detail the applicability and limitations of such a hybrid model by comparing data on fragmentation at low relativistic SIS/GSI-energies. 相似文献
122.
在Fe:LiNbO3中掺进Sc2O3和In2O3采用Czochralski技术生长Sc:In:Fe:LiNbO3晶体.测试Sc:In:Fe:LiNbO3晶体的红外光谱和抗光致散射能力.Sc(1mol;):In(2mol;):Fe:LiNbO3晶体OH-吸收峰移到3508cm-1,抗光致散射能力比Fe:LiNbO3晶体提高二个数量级.对Sc(1mol;):In(2mol;):Fe:LiNbO3晶体OH-吸收峰移动机理和抗光致散射能力增强的机理进行讨论.以Sc(1mol;):In(2mol;):Fe:LiNbO3晶体作存储元件,以Cu:KNSBN晶体作为位相共轭镜进行全息关联存储,试验结果表明全息关联存储的成象质量高、图象清晰完整、噪音小. 相似文献
123.
V.?N.?PanteleevEmail author A.?E.?Barzakh D.?V.?Fedorov M.?Menna F.?V.?Moroz Yu.?M.?Volkov 《The European Physical Journal A - Hadrons and Nuclei》2005,26(1):147-150
A new version of integrated target-ion source unit (ionising target) has been developed for the on-line production of radioactive
single-charged ions. The target is able to withstand temperatures up to 2500 °C and acts also as an ion source of the surface and laser ionisation. Off-line and on-line experiments with the ionising target,
housing tantalum foils as a target material, have been carried out at the IRIS (Investigation of Radioactive Isotopes on Synchrocyclotron)
facility. The off-line surface ionisation efficiency measured for stable atoms of Li, Rb and Cs was correspondingly 6% , 40%
and 55% at the target temperature of 2000 °C and 3-10% for atoms of rare-earth elements Sm, Eu, Tm and Yb at a temperature of 2200 °C. The off-line measured values of the ionisation efficiency for stable Gd and Eu atoms by the laser beam ionisation inside
the target were 1% and 7%, respectively. The radioactive beam intensities of neutron-deficient rare-earth nuclides from Eu
to Lu produced by the integrated target-ion source unit have been measured at a temperature of 2500 °C. The results of the integrated target-ion source unit use for on-line laser resonance ionisation spectroscopy study of neutron-deficient
Gd isotopes have been also presented. 相似文献
124.
M. N. Andronenko L. N. Andronenko W. Neubert D. M. Seliverstov 《The European Physical Journal A - Hadrons and Nuclei》2000,8(1):9-13
Nuclear temperatures were extracted from fragment yields obtained in inclusive measurements of p+A collisions at 1 GeV. All
thermometers based on double-isotopic yield-ratios provide temperatures T ≃ 4 MeV nearly independent on the target mass. 相似文献
125.
Sc12X团簇(X=B,C,N,Al,Si,P)的电子结构和稳定性 总被引:1,自引:0,他引:1
基于第一性原理,在密度泛函理论框架下,用广义梯度近似(GGA)研究二十面体Sc12X(X=B、C、N、Al、Si、P)中性和荷电团簇的电子结构和稳定性,系统计算了它们的基态束缚能(BE)、原子间平衡间距、最高占据轨道(HOMO)与最低占据轨道(LUMO)之间的能隙、局域电荷以及HOMO电子构型.研究表明,用C、Si原子或荷电后的B、N、Al、P离子分别替代团簇Sc13中心原子可以使其成为稳定的结构.Sc12X团簇束缚能改变的原因在于掺杂改变了中心原子或离子与表面原子的轨道杂化. 相似文献
126.
M. V. Ricciardi S. Lukić A. Kelić K.-H. Schmidt M. Veselsky 《The European physical journal. Special topics》2007,150(1):321-324
The construction of two new-generation complementary
RIB facilities in Europe, one based on the in-flight fragmentation
or fission (IFF) method (FAIR) and the other on the isotope
separation on-line (ISOL) method (EURISOL) is expected in the next
10-15 years. The reaction mechanisms, responsible for the
production of the secondary nuclei, along with the technical
constrains, have to be considered for the designs of the
facilities. In this work, we study which reaction mechanisms can
be exploited at best for the production of the secondary beams in
the two facilities. 相似文献
127.
Geometrical, electronic, and magnetic properties of the Sc-doped gold clusters, AunSc (n=1-8), have been studied using the density-functional theory within the generalized gradient approximation. An extensive structural search shows that the Sc atom in low-energy AunSc isomers tends to occupy the most highly coordinated position. The substitution of a Sc atom for an Au atom in the Aun+1 cluster markedly changes the structure of the host cluster. Moreover, we confirm that the ground-state Au6Sc cluster has a distortion to a lower D2h symmetry. The relative stabilities and electronic properties of the lowest-energy AunSc clusters are analyzed based on the averaged binding energies, second-order energy differences, fragmentation energies, chemical hardnesses, and HOMO-LUMO gaps. It is found that the magic Au3Sc cluster can be perceived as a superatom with high chemical stability and its HOMO-LUMO gap is larger than that of the closed-shell Zr@Au14 cluster. The high symmetry and spin multiplicity of the Au3Sc and Au6Sc clusters are responsible for their large vertical ionization potential and electron affinity. The magnetism calculations indicate that the magnetic moment of the Sc atom in the ground-state AunSc (n=2-8) clusters gradually decreases for even n and is completely quenched for odd n. 相似文献
128.
采用提拉法生长出了高浓度掺铒(35 at%)钇钪镓石榴石(Er:YSGG)激光晶体.测试了该晶体在340—1700 nm波段内的吸收光谱,对其中Er3+的实验能级进行了分析指认.用Er:YSGG的102个实验Stark能级,拟合了它的自由离子参数和晶体场参数,均方根误差(拟合精度)σ为10.34 cm-1.结果表明,参数化Stark能级的拟合结果与实验光谱符合得较好.将拟合得到的Er:YSGG实验结果与文献中已报道Er:YAG的自由离子参数和晶体场参数进行了比较.指出Er:YSGG具有较强的晶体场相互作用或许是其激光效率较高的主要原因之一. 相似文献
129.
On the importance of using scandium to normalize geochemical data preceding multivariate analyses applied to archaeometric pottery studies 总被引:1,自引:0,他引:1
This work enhances the importance on determining regional geochemical background by normalizing chemical data of archaeological ceramics, using one element as grain-size and mineralogical proxy, prior to any further statistical approach. It is well established that more relevant information can be derived from the concentration of any element when it is compared with some reference element. The main question is which element should be chosen to normalize concentration. A discussion on this issue is presented here.A case study is presented, which includes the geochemical tracing of Roman kilns productions, differentiating between and within two sedimentary basins pottery assembly, belonging to several Roman ceramic production centres identified in the Tagus and Sado basins of Portugal. Due to the homogeneity of the used raw materials (estuarine sediments), the distinction and establishment of signatures for each production center become difficult.A multivariate statistical approach after normalization of the chemical contents to a conservative element (Sc) is presented, well differentiating the three production centers and allowing the establishment of provenance for amphorae. 相似文献
130.
In order to elucidate the reaction mechanisms of reaction Sc+ with propargyl alcohol (PPA), the triplet potential energy surface for the reactions has been theoretically investigated using a DFT method. The geometries for the reactants, intermediates, transition states and products were completely optimized at B3LYP/DZVP level. The single point energy of each stationary point was calculated at MP4/(6-311+G** for C, H, O and Lanl2dz for Sc+) level. All the transition states were verified by the vibrational analysis and the internal reaction coordinate (IRC) calculations. The present results show that the reaction takes an insertion-elimination mechanism both along the O—H and C—O bond activation branches, but the C—O bond activation is much more favorable in energy than the O—H bond activation. All theoretical results not only support the existing conclusions inferred from early experiment, but also complement the pathway and mechanism for this reaction. 相似文献