全文获取类型
收费全文 | 8807篇 |
免费 | 251篇 |
国内免费 | 25篇 |
专业分类
化学 | 5743篇 |
晶体学 | 49篇 |
力学 | 171篇 |
数学 | 1052篇 |
物理学 | 2068篇 |
出版年
2021年 | 86篇 |
2020年 | 126篇 |
2019年 | 97篇 |
2018年 | 68篇 |
2016年 | 202篇 |
2015年 | 173篇 |
2014年 | 192篇 |
2013年 | 381篇 |
2012年 | 402篇 |
2011年 | 395篇 |
2010年 | 231篇 |
2009年 | 235篇 |
2008年 | 359篇 |
2007年 | 334篇 |
2006年 | 336篇 |
2005年 | 331篇 |
2004年 | 295篇 |
2003年 | 257篇 |
2002年 | 257篇 |
2001年 | 194篇 |
2000年 | 184篇 |
1999年 | 133篇 |
1998年 | 120篇 |
1997年 | 130篇 |
1996年 | 132篇 |
1995年 | 129篇 |
1994年 | 116篇 |
1993年 | 130篇 |
1992年 | 117篇 |
1991年 | 88篇 |
1990年 | 80篇 |
1989年 | 100篇 |
1988年 | 111篇 |
1987年 | 86篇 |
1986年 | 75篇 |
1985年 | 144篇 |
1984年 | 112篇 |
1983年 | 87篇 |
1982年 | 111篇 |
1981年 | 113篇 |
1980年 | 64篇 |
1979年 | 98篇 |
1978年 | 85篇 |
1977年 | 94篇 |
1976年 | 81篇 |
1975年 | 87篇 |
1973年 | 76篇 |
1968年 | 91篇 |
1967年 | 99篇 |
1966年 | 99篇 |
排序方式: 共有9083条查询结果,搜索用时 266 毫秒
1.
2.
Edelsbacher Philipp Redhammer Gnther Monkowius Uwe 《Monatshefte für Chemie / Chemical Monthly》2020,151(4):543-547
Monatshefte für Chemie - Chemical Monthly - Four members of a new series of paddle-wheel copper(II) complexes bearing cyclobutanecarboxylate as bridging ligand with pyridine derived ligands in... 相似文献
3.
4.
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
5.
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
6.
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
7.
Tricyclic skeletons have been generated from acyclic enyne precursors by using an intramolecular Pauson-Khand reaction in combination with aldol, Michael and alkylation reactions. 相似文献
8.
Let R be a discrete nonsingular equivalence relation on a standard probability space , and let V be an ergodic strongly asymptotically central automorphism of R. We prove that every V-invariant cocycle with values in a Polish group G takes values in an abelian subgroup of G.
The hypotheses of this result are satisfied, for example, if A is a finite set, a closed, shift-invariant subset, V is the shift, μ a shift-invariant and ergodic probability measure on X, the two-sided tail-equivalence relation on X, a shift-invariant subrelation which is μ-nonsingular, and a shift-invariant cocycle. 相似文献
9.
Thin Ca films were evaporated on Si(1 1 1) under UHV conditions and subsequently annealed in the temperature range 200–650 °C. The interdiffusion of Ca and Si was examined by ex situ Auger depth profiling. In situ monitoring of the Si 2p core-level shift by X-ray photoemission spectroscopy (XPS) was employed to study the silicide formation process. The formation temperature of CaSi2 films on Si(1 1 1) was found to be about 350 °C. Epitaxial growth takes place at T≥400 °C. The morphology of the films, measured by atomic force microscopy (AFM), was correlated with their crystallinity as analyzed by X-ray diffraction (XRD). According to measurements of temperature-dependent I–V characteristics and internal photoemission the Schottky-barrier height of CaSi2 on Si(1 1 1) amounts to qΦBn=0.25 eV on n-type and to qΦBp=0.82 eV on p-type silicon. 相似文献
10.
Johannes Elschner Rainer Hinder Gunther Schmidt 《Advances in Computational Mathematics》2002,16(2-3):139-156
This paper is devoted to the numerical study of diffraction by periodic structures of plane waves under oblique incidence. For this situation Maxwell's equations can be reduced to a system of two Helmholtz equations in R
2 coupled via quasiperiodic transmission conditions on the piecewise smooth interfaces between different materials. The numerical analysis is based on a strongly elliptic variational formulation of the differential problem in a bounded periodic cell involving nonlocal boundary operators. We obtain existence and uniqueness results for discrete solutions and provide the corresponding error analysis. 相似文献