全文获取类型
收费全文 | 2995篇 |
免费 | 103篇 |
国内免费 | 5篇 |
专业分类
化学 | 2132篇 |
晶体学 | 6篇 |
力学 | 45篇 |
数学 | 587篇 |
物理学 | 333篇 |
出版年
2021年 | 30篇 |
2020年 | 40篇 |
2019年 | 36篇 |
2018年 | 25篇 |
2016年 | 81篇 |
2015年 | 65篇 |
2014年 | 76篇 |
2013年 | 93篇 |
2012年 | 122篇 |
2011年 | 142篇 |
2010年 | 82篇 |
2009年 | 88篇 |
2008年 | 111篇 |
2007年 | 105篇 |
2006年 | 106篇 |
2005年 | 72篇 |
2004年 | 98篇 |
2003年 | 64篇 |
2002年 | 71篇 |
2001年 | 43篇 |
2000年 | 46篇 |
1999年 | 43篇 |
1998年 | 47篇 |
1997年 | 33篇 |
1996年 | 30篇 |
1995年 | 44篇 |
1994年 | 36篇 |
1993年 | 38篇 |
1992年 | 35篇 |
1991年 | 39篇 |
1990年 | 29篇 |
1989年 | 43篇 |
1988年 | 38篇 |
1987年 | 37篇 |
1986年 | 31篇 |
1985年 | 48篇 |
1984年 | 33篇 |
1983年 | 38篇 |
1982年 | 30篇 |
1981年 | 22篇 |
1980年 | 35篇 |
1979年 | 28篇 |
1978年 | 27篇 |
1977年 | 36篇 |
1976年 | 23篇 |
1975年 | 20篇 |
1973年 | 16篇 |
1971年 | 19篇 |
1934年 | 27篇 |
1933年 | 18篇 |
排序方式: 共有3103条查询结果,搜索用时 31 毫秒
11.
12.
13.
Georg Süss-Fink Ulf Bodensieck Lisa Hoferkamp Gerd Rheinwald Helen Stoeckli-Evans 《Journal of Cluster Science》1992,3(4):469-478
The reaction of trirutheniumdodecacarbonyl with various thioureas was found to give, depending upon the substituents and the reaction conditions, a large variety of tri-, tetra-, penta-, and hexanuclear ruthenium clusters. The ligand systems observed in the products are derived from the thioureas employed; the fragmentation of the thiourea molecules involve N-H, C-S, C-H, and C-N activation processes. 相似文献
14.
P. Thomsen-Schmidt K. Hasche G. Ulm K. Herrmann M. Krumrey G. Ade J. Stümpel I. Busch S. Schädlich A. Schindler W. Frank D. Hirsch M. Procop U. Beck 《Applied Physics A: Materials Science & Processing》2004,78(5):645-649
High-accuracy film thickness measurements in the range below 100 nm can be made by various complex methods like spectral ellipsometry (SE), scanning force microscopy (SFM), grazing incidence X-ray reflectometry (GIXR), or X-ray fluorescence analysis (XRF). The measurement results achieved with these methods are based on different interactions between the film and the probe. A key question in nanotechnology is how to achieve consistent results on a level of uncertainty below one nanometre with different techniques.Two different types of thickness standards are realised. Metal film standards for X-ray techniques in the thickness range 10 to 50 nm are calibrated by GIXR with monochromatised synchrotron radiation of 8048 eV. The results obtained at four different facilities show excellent agreement. SiO2 on Si standards for SE and SFM in the thickness range 6 to 1000 nm are calibrated by GIXR with monochromatised synchrotron radiation of 1841 eV and with a metrological SFM. Consistent results within the combined uncertainties are obtained with the two methods. Surfaces and interfaces of both types of standards are additionally investigated by transmission electron microscopy (TEM). PACS 61.10.Kw; 68.55.Jk; 06.20.Fn; 06.60.Mr; 07.79.Lh 相似文献
15.
16.
The category of small covariant functors from simplicial sets to simplicial sets supports the projective model structure [B. Chorny, W.G. Dwyer, Homotopy theory of small diagrams over large categories, preprint, 2005]. In this paper we construct various localizations of the projective model structure and also give a variant for functors from simplicial sets to spectra. We apply these model categories in the study of calculus of functors, namely for a classification of polynomial and homogeneous functors. In the n-homogeneous model structure, the nth derivative is a Quillen functor to the category of spectra with Σn-action. After taking into account only finitary functors—which may be done in two different ways—the above Quillen map becomes a Quillen equivalence. This improves the classification of finitary homogeneous functors by T.G. Goodwillie [T.G. Goodwillie, Calculus. III. Taylor series, Geom. Topol. 7 (2003) 645-711 (electronic)]. 相似文献
17.
18.
19.
Marko D. Mihovilovic Bernhard Müller Markus Spina Arjumand I. Durrani Peter Stanetty Georg Dazinger Karl Kirchner 《Monatshefte für Chemie / Chemical Monthly》2006,137(6):785-794
Summary. Recombinant Escherichia coli overexpressing Pseudomonas sp. NCIMB 9872 cyclopentanone monooxygenase (CPMO, EC 1.14.13.16) and Acinetobacter sp. NCIMB 9871 cyclohexanone monooxygenase (CHMO, EC 1.14.13.22) have been utilized in whole-cell Baeyer-Villiger biotransformations of prochiral bicycloketones. A significant difference in substrate acceptance and stereoselectivity was
observed for bicyclo[3.3.0] and bicyclo[4.3.0] substrates. A plausible mechanism of these transformations was established
by means of high level DFT/B3LYP calculations suggesting an essential difference in electronic requirements for a successful
enzymatic conversion, which was similarly encountered in recombinant whole-cell mediated biooxidations. Some of the lactones
produced in the biocatalytic Baeyer-Villiger oxidation represent key intermediates for the synthesis of indole alkaloids. 相似文献
20.
Georg v. Georgievics 《Monatshefte für Chemie / Chemical Monthly》1887,8(1):577-579
Ohne Zusammenfassung 相似文献