全文获取类型
收费全文 | 150篇 |
免费 | 30篇 |
国内免费 | 3篇 |
专业分类
化学 | 90篇 |
综合类 | 1篇 |
数学 | 56篇 |
物理学 | 36篇 |
出版年
2018年 | 1篇 |
2016年 | 6篇 |
2015年 | 1篇 |
2014年 | 3篇 |
2013年 | 2篇 |
2012年 | 3篇 |
2011年 | 5篇 |
2010年 | 1篇 |
2009年 | 8篇 |
2008年 | 4篇 |
2007年 | 3篇 |
2006年 | 5篇 |
2005年 | 2篇 |
2004年 | 4篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 5篇 |
1988年 | 1篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 10篇 |
1980年 | 4篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 9篇 |
1973年 | 5篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 3篇 |
1969年 | 1篇 |
1966年 | 1篇 |
1879年 | 1篇 |
排序方式: 共有183条查询结果,搜索用时 15 毫秒
61.
本文研究了俘获于掺杂VO++离子的(NH4)2Zn(SO4)2·6H2O单晶中NH3+自由基离子的ESR.从实验上分别测出π电子自由基NH3+的14N和15N核超精细分裂.结果表明,氮核超精细偶合张量具有近似于圆柱形对称。对于15N来说,A11=44.8,A22=19.3,A33=17.8高斯.对于14N来说,A11=31.1,A22=12.5,A33=11.8高斯.在室温下,NH3+自由基绕A11方向作圆锥体运动.文中最后讨论了NH3+自由基离子的可能生成机理。 相似文献
62.
Single crystals of the cobalt skutterudites CoP3, CoAs3 and CoSb3 have been prepared by the chemical vapor transport technique using chlorine as the transport agent. Chemical analysis and density measurements were used to determine accurately the stoichiometry of these crystals. Physical properties of chemically pure single crystals were obtained by X-ray diffraction, magnetic susceptibility and electrical measurements. CoP3 is a diamagnetic semiconductor with an optical band gap of 0.45 eV. CoAs3 and CoSb3 are also diamagnetic and show an increase in their resistivity as a function of increasing temperature. In addition, they do not give any measurable absorption edge but absorb radiation at all frequencies from 0.4 to 4.3 eV. 相似文献
63.
Auslender, Cominetti and Haddou have studied, in the convex case, a new family of penalty/barrier functions. In this paper, we analyze the asymptotic behavior of augmented penalty algorithms using those penalty functions under the usual second order sufficient optimality conditions, and present order of convergence results (superlinear convergence with order of convergence 4/3). Those results are related to the analysis of pure penalty algorithms, as well as augmented penalty using a quadratic penalty function. Limited numerical examples are presented to appreciate the practical impact of this local asymptotic analysis.This research was partially supported by NSERC grant OGP0005491 相似文献
64.
We introduce the set of bicomplex numbers
which is a commutative ring with zero divisors defined by
where
We present the conjugates and the moduli associated with the bicomplex numbers. Then we study the bicomplex Schr?dinger equation
and found the continuity equations. The discrete symmetries of the system of equations describing the bicomplex Schr?dinger
equation are obtained. Finally, we study the bicomplex Born formulas under the discrete symmetries. We obtain the standard
Born’s formula for the class of bicomplex wave functions having a null hyperbolic angle. 相似文献
65.
Erlend Fornæss Wold 《Journal of Geometric Analysis》2011,21(2):252-255
We will show that the currents of Duval and Sibony can be constructed easily from Poletsky disks. 相似文献
66.
L. Eriksson J. Damborsky M. Earll E. Johansson J. Trygg S. Wold 《SAR and QSAR in environmental research》2013,24(5-6):481-499
When X and Y are multivariate, the two-block partial least squares (PLS) method is often used. In this paper, we outline an extension addressing a special case of the three-block (X/Y/Z) problem, where Z sits "under" Y. We have called this approach three-block bi-focal PLS (3BIF-PLS). It views the X/Y relationship as the dominant problem, and seeks to use the additional information in Z in order to improve the interpretation of the Y-part of the X/Y association. Two data sets are used to illustrate 3BIF-PLS. Example I relates to single point mutants of haloalkane dehalogenase from Sphingomonas paucimobilis UT26 and their ability to transform halogenated hydrocarbons, some of which are found as organic pollutants in soil. Example II deals with soil remediation capability of bacteria. Whole bacterial communities are monitored over time using "DNA-fingerprinting" technology to see how pollution affects population composition. Since the data sets are large, hierarchical multivariate modelling is invoked to compress data prior to 3BIF-PLS analysis. It is concluded that the 3BIF-PLS approach works well. The paper contains a discussion of pros and cons of the method, and hints at further developmental opportunities. 相似文献
67.
Detailed optical measurements near the band gap of the system GaP-ZnSe have provided evidence for sharp decreases in the energy band gaps for small levels of solution, here studied for compositions close to pure GaP. This is seen for both the indirect gap and the direct gap near the pure GaP end. Similar behavior has been observed in other solid solutions of systems having different valences. Deviations from the behavior proposed by Fischer, Glicksman and Van Vechten are suggested as due to the effect on electron energy states of the effective high density of ions at dilute solution levels. 相似文献
68.
Y. Shapira D.H. Ridgley K. Dwight A. Wold K.P. Martin J.S. Brooks P.A. Lee 《Solid State Communications》1985,54(7):593-596
At 0.5 ≤ T ≤ 4.2 K samples of Cd0.99Mn0.01Se which are near the metal-insulator transition exhibit a large positive magnetoresistance (MR) in fields H ∽ 10 k0e. The effect is accompanied by an increase in the Hall coefficient and a decrease in the Hall mobility. At the lowest temperatures and for fields well above 10 k0e a small negative MR is observed. The positive MR is tentatively attributed to an increase in the screening radius rs, which leads to enhanced Coulomb-potential fluctuations. 相似文献
69.
70.