全文获取类型
收费全文 | 5234篇 |
免费 | 162篇 |
国内免费 | 7篇 |
专业分类
化学 | 3525篇 |
晶体学 | 59篇 |
力学 | 67篇 |
数学 | 545篇 |
物理学 | 1207篇 |
出版年
2021年 | 41篇 |
2020年 | 45篇 |
2019年 | 53篇 |
2016年 | 92篇 |
2015年 | 93篇 |
2014年 | 104篇 |
2013年 | 163篇 |
2012年 | 175篇 |
2011年 | 201篇 |
2010年 | 142篇 |
2009年 | 108篇 |
2008年 | 179篇 |
2007年 | 177篇 |
2006年 | 185篇 |
2005年 | 172篇 |
2004年 | 154篇 |
2003年 | 151篇 |
2002年 | 144篇 |
2001年 | 136篇 |
2000年 | 126篇 |
1999年 | 71篇 |
1998年 | 65篇 |
1997年 | 59篇 |
1996年 | 98篇 |
1995年 | 86篇 |
1994年 | 102篇 |
1993年 | 72篇 |
1992年 | 73篇 |
1991年 | 72篇 |
1990年 | 63篇 |
1989年 | 60篇 |
1988年 | 60篇 |
1987年 | 80篇 |
1986年 | 75篇 |
1985年 | 80篇 |
1984年 | 75篇 |
1983年 | 62篇 |
1982年 | 70篇 |
1981年 | 72篇 |
1980年 | 59篇 |
1979年 | 64篇 |
1978年 | 66篇 |
1977年 | 66篇 |
1976年 | 67篇 |
1975年 | 63篇 |
1974年 | 62篇 |
1973年 | 54篇 |
1971年 | 30篇 |
1968年 | 28篇 |
1957年 | 29篇 |
排序方式: 共有5403条查询结果,搜索用时 15 毫秒
1.
2.
3.
Wolfram Bremser Roland Becker Heinrich Kipphardt Petra Lehnik-Habrink Ulrich Panne Antje Töpfer 《Accreditation and quality assurance》2006,11(10):489-495
ISO Guide 35 deals with RM stability issues and scrutinizes the evaluation of stability testing results under the assumption that either there is no trend at all (a rather rare situation), or any observed deterministic change is insignificant and thus can be neglected. However, market demands for reliable reference materials are obviously not limited to stable or at least seemingly stable materials. In many analytical applications, analytes and measurands under consideration are known, or at least suspected, to be unstable on time scales that may vary widely from measurand to measurand. The Federal Institute for Materials Research and Testing (BAM) has developed (and successfully uses) an integrated approach in its certification practice. The approach is based on an initial stability study and subsequent post-certification monitoring. Data evaluation is model-based and takes advantage of all information collected in the stability testing scheme(s). It thus allows one to deal with any kind of instability observed, to assess limiting time intervals at any stress condition in the range tested, to estimate a final expiry date for materials with detected instabilities or the maximum admissible re-testing interval for seemingly stable materials, and to assess maximum admissible stress loads during delivery of the material to the customer. The article describes (and exemplifies) typical study layout, the model selection, and the integrated data assessment. 相似文献
4.
5.
F. Meyer 《Fresenius' Journal of Analytical Chemistry》1885,24(1):617
Ohne Zusammenfassung 相似文献
6.
J. R. Lindle W. W. Bewley I. Vurgaftman J. R. Meyer J. L. Johnson M. L. Thomas W. E. Tennant 《Physica E: Low-dimensional Systems and Nanostructures》2004,20(3-4):558
A self-referencing, optical modulation technique was used to measure the negative luminescence efficiencies of an array of mid-wave infrared HgCdTe photodiodes with cutoff wavelength 4.6 μm as a function of sample temperature. The internal efficiency at a wavelength of 4 μm was 93% at 295 K, and nearly independent of temperature in the 240–300 K range. This corresponds to an apparent temperature reduction >50 K at room temperature and >30 K at 240 K. Moreover, the reverse-bias saturation current density was only 0.13 A/cm2. The measured transmission and emission spectra were simulated using empirical HgCdTe absorption formulas from the literature. 相似文献
7.
Geerk J. Linker G. Meyer O. Politis C. Ratzel F. Smithey R. Strehlau B. Xiong G. C. 《Zeitschrift für Physik B Condensed Matter》1987,67(4):507-511
Thin superconducting films of La1.8Sr0.2CuO4 have been prepared by magnetron sputter deposition and subsequent temperature treatment. The composition of the films has been determined by Rutherford backscattering and the structure by thin film X-ray diffraction. The onset of superconductivity was about 32 K and the midpoint near 28 K. Defect production in the films by He ion bombardment revealed a drasticT
c
reduction with a sensitivity similar to that observed in the Chevrel phases. Oxygen implantation and subsequent annealing led to an enhancement of theT
c
onset. 相似文献
8.
A. Craig W. H. Jacobson A. Meyer N. Welwart A. Seuthe H. N. Marr B. S. Evans G. E. F. Lundell J. A. Scherrer E. Stelling F. J. Mück A. Kling A. Lassieur L. Bertiaux C. C. Bissett P. de Pauw J. Heslinga A. Bartsch R. E. Lee W. H. Fegeley F. H. Reichel und E. Saz 《Fresenius' Journal of Analytical Chemistry》1927,71(1-2):83-90
Ohne Zusammenfassung 相似文献
9.
Andrzej Dabrowski Erich Robens Peter Klobes Klaus Meyer Przemyslaw Podkocielny 《Particle & Particle Systems Characterization》2003,20(5):311-322
Since a comprehensive survey published in 1999 [1] much work was done in standardizing measuring methods to characterize the surface geometry of dispersed and/or porous solids and to certify reference materials. The present paper is an extension of a short communication [2]. It gives a survey on existing standards and reports on new drafts and proposals. 相似文献
10.