全文获取类型
收费全文 | 1300篇 |
免费 | 35篇 |
国内免费 | 15篇 |
专业分类
化学 | 868篇 |
晶体学 | 17篇 |
力学 | 13篇 |
数学 | 257篇 |
物理学 | 195篇 |
出版年
2022年 | 13篇 |
2021年 | 26篇 |
2020年 | 11篇 |
2019年 | 18篇 |
2018年 | 29篇 |
2017年 | 14篇 |
2016年 | 27篇 |
2015年 | 40篇 |
2014年 | 50篇 |
2013年 | 83篇 |
2012年 | 64篇 |
2011年 | 83篇 |
2010年 | 46篇 |
2009年 | 47篇 |
2008年 | 75篇 |
2007年 | 53篇 |
2006年 | 51篇 |
2005年 | 66篇 |
2004年 | 47篇 |
2003年 | 47篇 |
2002年 | 49篇 |
2001年 | 21篇 |
2000年 | 12篇 |
1999年 | 13篇 |
1998年 | 8篇 |
1997年 | 20篇 |
1996年 | 16篇 |
1995年 | 28篇 |
1994年 | 18篇 |
1993年 | 12篇 |
1992年 | 13篇 |
1991年 | 14篇 |
1990年 | 18篇 |
1989年 | 13篇 |
1988年 | 13篇 |
1987年 | 11篇 |
1986年 | 16篇 |
1985年 | 15篇 |
1984年 | 17篇 |
1983年 | 8篇 |
1982年 | 14篇 |
1981年 | 16篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 8篇 |
1975年 | 10篇 |
1968年 | 6篇 |
1965年 | 6篇 |
1962年 | 6篇 |
排序方式: 共有1350条查询结果,搜索用时 15 毫秒
171.
172.
Detection of apoptosis is one of the main criteria of preimplantation embryo growth potential assessment. Recent developments in lab-on-a-chip techniques has led to apoptosis detection and monitoring on a single cell or embryo level. However, single embryo apoptosis detection without a change in embryo developmental competence and post-examination "recovery" still remains a challenge. In this paper we present a lab-on-a-chip, co-working with miniaturized optical instrumentation, which allows supravital examination of single embryos for the presence of apoptotic blastomers with full after lab-on-a-chip study "recovery" and maintenance of their further developmental capacity. 相似文献
173.
Zbigniew Romanowski 《Molecular physics》2013,111(13):1339-1348
The h-adaptive, high order finite element method is applied to solve a second order one dimension eigenvalue problem. The finite element formulation for the Lobatto basis is given, for which basis functions of arbitrary order can be constructed. The adaptive algorithm is simple, yet very efficient and straightforward to implement. The algorithm is based on the observation that the expansion coefficients of Lobatto basis functions decay rapidly. It allows evaluating the smallest eigenvalues simultaneously with the comparable accuracy for all eigenvalues. The presented algorithm is applied to solve the radial Schrödinger equation with the Coulomb and the Woods–Saxon potentials. For both potentials the convergence rate is presented. After seven adaptive iterations nine-digit accuracy was obtained. 相似文献
174.
Zbigniew Florjaczyk Wodzimierz Krawiec Wadysaw Wieczorek Maciej Siekierski 《Journal of Polymer Science.Polymer Physics》1995,33(4):629-635
The conducting properties of solid electrolytes comprising random poly(ethylene oxide-co-propylene oxide) (of 84 : 16 monomer units mole ratio) and lithium, sodium, potassium, cesium, and rubidium salts have been studied. The systems containing some lithium or sodium salts achieved conductivity levels as high as 10?5–10?4 S/cm at ambient temperature and greater than 10?3 S/cm at 100°C. However, the systems with rubidium and cesium salts exhibit conductivities a few orders of magnitude smaller. DSC studies show that the electrolytes studied are characterized by a high content of an amorphous phase (95–100%). It is suggested that the copolymer exhibits lower complexing abilities than that of poly(ethylene oxide), which results in a higher flexibility of electrolytes containing small cations and poor dissociation of the salts having large cations. © 1995 John Wiley & Sons, Inc. 相似文献
175.
The influence of charging effects on the transport characteristics of a molecular wire bridging two metallic electrodes in the limit of weak contacts is studied by the generalized Breit–Wigner formula. Molecule is modeled as a quantum dot with discrete energy levels, while the coupling to the electrodes is treated within a broad-band theory. Owing to this model we find self-consistent occupation of particular energy levels and orbital energies of the wire in the presence of transport. The nonlinear conductance and current–voltage characteristics are investigated as a function of bias voltage in the case of symmetric and asymmetric coupling to the electrodes. It is shown that the shape of those curves are determined by the combined effect of the electronic structure of the molecule and by electron–electron repulsion. 相似文献
176.
Zbigniew Binderman 《Mathematische Nachrichten》1993,161(1):239-252
In this paper, shifts for a right invertible operator D induced by an analytic function acting in a linear complete metric space are considered. The case when these shifts coincide with the operator - valued function on a set which contains the set of all D-polynomials and the set of all exponentials is studied. It is shown that in this case these shifts are R-shifts and D-shifts (cf. [1], [10]). 相似文献
177.
Zbigniew Kisiel Lech Pszczó?kowski Manfred Winnewisser Eric Herbst 《Journal of Molecular Spectroscopy》2005,233(2):231-243
We report the results of a comprehensive reinvestigation of the rotational spectrum of diethyl ether based on broadband millimetre-wave spectra recently recorded at The Ohio State University and in Warsaw, covering the frequency region 108-366 GHz. The data set for the ground vibrational state of trans-trans diethyl ether has been extended to over 2000 lines and improved spectroscopic constants have been determined. Rotational spectra in the first excited vibrational states of the three lowest vibrational modes of trans-trans-diethyl ether, ν20, ν39, and ν12 have been assigned. The v20 = 1 and v39 = 1 states are near 100 cm−1 in vibrational term value and are coupled by a strong c-axis Coriolis interaction, which gives rise to many spectacular manifestations in the rotational spectrum. All of these effects have been successfully fitted for a dataset comprising over 3000 transitions, leading to precise determination of the energy difference between these states, (ΔE/hc)=10.400222(5) cm−1. A newly developed software package for assignment and analysis of broadband spectra is described and made available. 相似文献
178.
179.
Z. Walczak 《Acta Mathematica Hungarica》2003,101(3):179-191
We consider certain modified Szász-Mirakyan operators A
n
(f;r) in polynomial weight spaces of functions of one variable and we study approximation properties of these operators.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
180.