全文获取类型
收费全文 | 3126篇 |
免费 | 116篇 |
国内免费 | 8篇 |
专业分类
化学 | 2243篇 |
晶体学 | 11篇 |
力学 | 41篇 |
数学 | 360篇 |
物理学 | 595篇 |
出版年
2023年 | 15篇 |
2022年 | 16篇 |
2021年 | 39篇 |
2020年 | 63篇 |
2019年 | 46篇 |
2018年 | 17篇 |
2017年 | 20篇 |
2016年 | 88篇 |
2015年 | 74篇 |
2014年 | 87篇 |
2013年 | 146篇 |
2012年 | 187篇 |
2011年 | 208篇 |
2010年 | 111篇 |
2009年 | 97篇 |
2008年 | 170篇 |
2007年 | 157篇 |
2006年 | 142篇 |
2005年 | 146篇 |
2004年 | 167篇 |
2003年 | 117篇 |
2002年 | 137篇 |
2001年 | 57篇 |
2000年 | 58篇 |
1999年 | 43篇 |
1998年 | 37篇 |
1997年 | 43篇 |
1996年 | 45篇 |
1995年 | 50篇 |
1994年 | 58篇 |
1993年 | 47篇 |
1992年 | 53篇 |
1991年 | 33篇 |
1990年 | 38篇 |
1989年 | 42篇 |
1988年 | 37篇 |
1987年 | 28篇 |
1985年 | 40篇 |
1984年 | 22篇 |
1983年 | 15篇 |
1982年 | 24篇 |
1981年 | 28篇 |
1980年 | 21篇 |
1979年 | 22篇 |
1978年 | 16篇 |
1977年 | 20篇 |
1976年 | 18篇 |
1975年 | 21篇 |
1973年 | 14篇 |
1970年 | 11篇 |
排序方式: 共有3250条查询结果,搜索用时 15 毫秒
1.
2.
Mechanistic Aspects of a Highly Active Dinuclear Zinc Catalyst for the Co‐polymerization of Epoxides and CO2 下载免费PDF全文
Stefan Kissling Peter T. Altenbuchner Dr. Maximilian W. Lehenmeier Dr. Eberhardt Herdtweck Dr. Peter Deglmann Dr. Uwe B. Seemann Prof. Dr. Bernhard Rieger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8148-8157
The dinuclear zinc complex reported by us is to date the most active zinc catalyst for the co‐polymerization of cyclohexene oxide (CHO) and carbon dioxide. However, co‐polymerization experiments with propylene oxide (PO) and CO2 revealed surprisingly low conversions. Within this work, we focused on clarification of this behavior through experimental results and quantum chemical studies. The combination of both results indicated the formation of an energetically highly stable intermediate in the presence of propylene oxide and carbon dioxide. A similar species in the case of cyclohexene oxide/CO2 co‐polymerization was not stable enough to deactivate the catalyst due to steric repulsion. 相似文献
3.
Back Cover: Reactions of Group 4 Metallocenes with Monosubstituted Acetonitriles: Keteniminate Formation versus CC Coupling (Chem. Eur. J. 8/2015) 下载免费PDF全文
4.
Erwin Bolthausen Jean-Dominique Deuschel Uwe Schmock 《Probability Theory and Related Fields》1993,95(3):283-310
Summary We discuss the limiting path measures of Markov processes with either a mean field or a polaron type interaction of the paths. In the polaron type situation the strength is decaying at large distances on the time axis, and so the interaction is of short range in time. In contrast, in the mean field model, the interaction is weak, but of long range in time. Donsker and Varadhan proved that for the partition functions, there is a transition from the polaron type to the mean field interaction when passing to a limit by letting the strength tend to zero while increasing the range. The discussion of the path measures is more subtle. We treat the mean field case as an example of a differentiable interaction and discuss the transition from the polaron type to the mean field interaction for two instructive examples.Research supported by the Swiss National Foundation (21-29833.90)This article was processed by the authors using the Springer-Verlag TEX ProbTh macro package 1991. 相似文献
5.
D.W. Mueller JrA.L. Crosbie 《Journal of Quantitative Spectroscopy & Radiative Transfer》2002,74(1):43-68
Three-dimensional radiative transfer in an anisotropic scattering medium exposed to spatially varying, collimated radiation is studied. The generalized reflection function for a semi-infinite medium with a very general scattering phase function is the focus of this investigation. An integral transform is used to reduce the three-dimensional transport equation to a one-dimensional form, and a modified Ambarzumian's method is applied to formulate a nonlinear integral equation for the generalized reflection function. The integration is over both the polar and azimuthal angles; hence, the integral equation is said to be in the double-integral form. The double-integral, reflection function formulation can handle a variety of anisotropic phase functions and does not require an expansion of the phase function in a Legendre polynomial series. Complicated kernel transformations of previous single-integral studies are eliminated. Single and double scattering approximations are developed. Numerical results are presented for a Rayleigh phase function to illustrate the computational characteristics of the method and are compared to results obtained with the single-integral method. Agreement between the two approaches is excellent; however, as the transform variable increases beyond five the number of quadrature points required for the double-integral method to produce accurate solutions significantly increases. A new interpolation scheme produces accurate results when the transform variable is large. 相似文献
6.
7.
O. Perru F. Ibrahim O. Bajeat C. Bourgeois F. Clapier E. Cottereau C. Donzaud M. Ducourtieux S. Galès D. Guillemaud-Mueller C. Lau H. Lefort F. Le Blanc A. C. Mueller J. Obert N. Pauwels J. C. Potier F. Pougheon J. Proust B. Roussière J. Sauvage O. Sorlin D. Verney 《Physics of Atomic Nuclei》2003,66(8):1421-1427
The PARRNe facility has been used to produce neutron-rich isotopes 83,84Gaby the ISOL method. Their decay has been studied, and β-γ coincidence and γ-γ coincidence data were collected as a function of time. The first two excited levels in 83Ge and the first excited level in 84Ge have been measured for the first time. 相似文献
8.
9.
We have detected a fundamental pulse-compression limit for high-nonlinear fibers in the normal dispersion regime near the zero-dispersion wavelength. The desired generation of a broadband continuum by self-phase modulation is limited by already small amounts of third-order dispersion (TOD), which results in pulse splitting above a critical pulse power. We investigate the critical fiber length in dependence on pulse- and fiber parameters. 相似文献
10.