全文获取类型
收费全文 | 410篇 |
免费 | 8篇 |
专业分类
化学 | 241篇 |
力学 | 2篇 |
数学 | 47篇 |
物理学 | 128篇 |
出版年
2020年 | 7篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 4篇 |
2016年 | 10篇 |
2015年 | 8篇 |
2014年 | 11篇 |
2013年 | 11篇 |
2012年 | 16篇 |
2011年 | 25篇 |
2010年 | 16篇 |
2009年 | 12篇 |
2008年 | 19篇 |
2007年 | 25篇 |
2006年 | 17篇 |
2005年 | 12篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2002年 | 15篇 |
2001年 | 4篇 |
2000年 | 10篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1993年 | 13篇 |
1992年 | 10篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 9篇 |
1973年 | 7篇 |
1971年 | 3篇 |
1969年 | 5篇 |
1968年 | 3篇 |
1966年 | 3篇 |
1961年 | 3篇 |
1958年 | 4篇 |
1957年 | 3篇 |
1954年 | 2篇 |
排序方式: 共有418条查询结果,搜索用时 15 毫秒
11.
The potential of Fe(CO)4(η1-dppf) (dppf = 1,1′-bis(diphenylphosphino)ferrocene) as a precursor for heterometallic species is fully expanded in the synthesis of (OC)4Fe(μ-dppf)Cr(CO)5, (OC)4Fe(μ-dppf)W(CO)5, and (OC)4Fe(μ-dppf)Mn2(CO)9, all of which have been characterized by IR, NMR (1H and 31P) and elemental analyses. The low energy requirement of TMNO (Me3NO · 2H2O)decarbonylation allows the formation of monosubstituted Mn2(CO)10 as the major product. This aspect is further substantiated by the isolation of Mn4(CO)18(μ-dppf) in which the single bridging of a diphosphine group between two Mn2(CO)9 moieties is unprecedented. 相似文献
12.
Precise values of energies and widths of low-lying resonances in some rare-gas atom systems (Ar-Ar, Ne-Kr, Ne-Xe) are reported. 相似文献
13.
14.
The problem of calculation of Sturmian functions (positive energy Weinberg states) for nonlocal (exchange) interactions is considered. It is shown that the method of continued fractions proposed by Horáek and Sasakawa makes the calculation of Sturmian eigenfunctions and eigenvalues feasible even for complicated nonlocal interactions. As an example Sturmian functions and Sturmian eigenvalues for the low energy electron-hydrogen scattering in the static exchange approximation are calculated. In addition a very general proof of convergence of the method of continued fractions is presented.Dedicated to the memory of Professor Jozef Kvasnica. 相似文献
15.
G. Horányi 《Journal of Radioanalytical and Nuclear Chemistry》1989,137(1):23-28
The role of electrochemistry in the discovery and interpretation of the alleged cold nuclear fusion is discussed. 相似文献
16.
A modified Bridgman method is described, which makes it possible to prepare homogeneous BiTeI crystals using excess iodine. At room temperature the values of the electrical conductivity of the crystals range around 2000 –1 cm–1, the Hall constant value about 0·09 cm–3 coul–1, the Seebeck coefficient about 50 V K–1. In connection with the assumption of super-stoichiometric iodine content we expect there exist point defects in the crystals, where Te atoms are replaced with I atoms, which gives rise to electric conductivity. On the basis of the temperature dependence of the electron mobility one can suppose a mixed mechanism of the scattering of the free carriers by the acoustic branch of lattice vibrations and by ionized impurities. 相似文献
17.
The Galerkin method of solution of integral equations using splines is proposed. This method is applied to the Lippmann-Schwinger equation. Bound state energies and correspondingt-matrices are calculated for various potentials. This method can also be applied to reduce the Faddeev equation to the one-dimensional ones.The authors are grateful to Doc. J.Kvasnica for number of useful discussions and to M.erný for help with numerical calculations. 相似文献
18.
In the present study, the competitive adsorption characteristics of binary and ternary heavy metal ions Pb2+, Cu2+, and Cd2+ on microporous titanosilicate ETS-10 were investigated in batch systems. Pure microporous titanosilicate ETS-10 was synthesized with P25 as the Ti source and characterized by the techniques of X-ray diffraction (XRD), field emission-scanning electron microscope (FESEM), nitrogen adsorption, and zeta-potential. Equilibrium and kinetic adsorption data showed that ETS-10 displays a high selectivity toward one metal in a two-component or a three-component system with an affinity order of Pb2+ > Cd2+ > Cu2+. The equilibrium behaviors of heavy metals species with stronger affinity toward ETS-10 can be described by the Langmuir equation while the adsorption kinetics of the metals can be well fitted to a pseudo-second-order (PSO) model. 相似文献
19.
20.
New bent-core liquid crystalline dimers with W-shaped molecular geometry have been prepared and studied. We have modified the dimer shape by variation of the connecting part between two bent-core units and changing the terminal chains (perfluoroalkyl, siloxanealkyl). Additionally, we have altered the inner bend angle value (120°, 60° and 148°) by utilization of different aromatic units. Mesomorphic properties of new dimers were established based on the texture observation in the polarizing microscope and DSC measurements. Moreover, x-ray structural analysis has been performed for selected dimers to confirm phase identification. For most of the studied dimers, nematic or columnar phases have been detected, for several compounds appearing in a nematic-columnar phase sequence on cooling from the isotropic phase. The studied dimers showed richer polymorphism than their monomeric counterparts. 相似文献