全文获取类型
收费全文 | 168693篇 |
免费 | 3602篇 |
国内免费 | 1983篇 |
专业分类
化学 | 93127篇 |
晶体学 | 2728篇 |
力学 | 7260篇 |
综合类 | 102篇 |
数学 | 16903篇 |
物理学 | 54158篇 |
出版年
2020年 | 1312篇 |
2018年 | 1410篇 |
2017年 | 1284篇 |
2016年 | 2350篇 |
2015年 | 1788篇 |
2014年 | 2523篇 |
2013年 | 6993篇 |
2012年 | 5486篇 |
2011年 | 6853篇 |
2010年 | 4487篇 |
2009年 | 4337篇 |
2008年 | 5947篇 |
2007年 | 5958篇 |
2006年 | 5856篇 |
2005年 | 5559篇 |
2004年 | 4880篇 |
2003年 | 4354篇 |
2002年 | 4203篇 |
2001年 | 5012篇 |
2000年 | 3769篇 |
1999年 | 3206篇 |
1998年 | 2741篇 |
1997年 | 2632篇 |
1996年 | 2514篇 |
1995年 | 2404篇 |
1994年 | 2171篇 |
1993年 | 2047篇 |
1992年 | 2313篇 |
1991年 | 2293篇 |
1990年 | 2208篇 |
1989年 | 2143篇 |
1988年 | 2178篇 |
1987年 | 2155篇 |
1986年 | 2009篇 |
1985年 | 2610篇 |
1984年 | 2736篇 |
1983年 | 2240篇 |
1982年 | 2591篇 |
1981年 | 2412篇 |
1980年 | 2391篇 |
1979年 | 2456篇 |
1978年 | 2561篇 |
1977年 | 2485篇 |
1976年 | 2498篇 |
1975年 | 2376篇 |
1974年 | 2205篇 |
1973年 | 2440篇 |
1972年 | 1557篇 |
1968年 | 1312篇 |
1967年 | 1286篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Jeroen J. L. M. Cornelissen W. Sander Graswinckel Alan E. Rowan Nico A. J. M. Sommerdijk Roeland J. M. Nolte 《Journal of polymer science. Part A, Polymer chemistry》2003,41(11):1725-1736
The conformational properties of polymers derived from isocyanodipeptides have been investigated with a combination of model calculations, X‐ray diffraction, and circular dichroism spectroscopy. Depending on the configuration of the side chains, defined arrays of hydrogen bonds along the polymeric backbone are formed. This leads to a well‐defined conformation as, for example, expressed in the formation of lyotropic liquid‐crystalline phases and increased helical stability. Upon the disruption of the hydrogen bonds by a strong acid, a less well‐defined macromolecular conformation is observed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1725–1736, 2003 相似文献
92.
M Lepère R Gobeille V.Malathy Devi M.A.H Smith B Aoaeh A.W Mantz 《Journal of Molecular Spectroscopy》2004,224(1):7-12
We have analyzed the methyl fluoride RQ(J,0)Q branch lines located near 1475 cm−1 using a simultaneous multi-spectrum fitting technique. In this analysis we have used previously recorded diode-laser data in which we collected many data points covering only one or two Q branch lines in a particular run. The analysis consists of simultaneously fitting 57 spectra collected with numerous pressure and path length conditions for all absorption lines. The data are concatenated to create one continuous spectrum of the Q branch. We have determined the intensity and self-broadened widths at 296 K for 23 RQ(J,0) lines. 相似文献
93.
M. Stangl V. Dittel J. Acker V. Hoffmann W. Gruner S. Strehle K. Wetzig 《Applied Surface Science》2005,252(1):158-161
At room temperature electroplated copper layers exhibit changes in resistivity, residual stress, and microstructure. This process, known as self-annealing, is intimately linked to the release of organic impurities, which stem from the incorporation of organic additives into the Cu layer in the course of the electroplating process. The behavior of these impurities during self-annealing, represented by the carbon content, could be detected by analytical radio frequency glow discharge optical emission spectrometry (GD-OES) and carrier gas hot extraction (CGHE). The precondition of a quantitative determination is a surface cleaning procedure to remove adsorbed organics from the copper surface. It was observed that at first almost all impurities have to leave the Cu metallization before an accelerated abnormal grain growth can start. The small amount of remaining organic species after self-annealing could be quantified by both examination techniques, GD-OES and CGHE. 相似文献
94.
W. Hampe 《Fresenius' Journal of Analytical Chemistry》1885,24(1):588-590
Ohne Zusammenfassung 相似文献
95.
96.
Blood serum samples were irradiated by monochromatic synchrotron radiation (15 keV) and by 2.4-MeV protons to compare their performance for the detection of trace elements by x-ray fluorescence (XRF) spectrometry. Absolute concentration assignment was based on the addition of an internal standard and on a method which uses the incoherent and coherent radiation as a flux monitor of the incoming beam. Preliminary experiments with a synchrotron XRF microprobe are reported. 相似文献
97.
98.
99.
D. N. Karimov E. A. Krivandina Z. I. Zhmurova B. P. Sobolev V. A. Bezhanov S. P. Chernov G. M. Shapochkin 《Crystallography Reports》2006,51(6):1009-1015
Crystalline materials that are transparent in the vacuum UV spectral region and currently used have been reviewed. Transmission of crystals of solid solutions with the fluorite structure Ca1?x R xF2+x (R = Sc, Y, La, Yb, Lu) in the UV and vacuum UV spectral regions has been investigated. It is shown that application of different methods of purification of fluorides from some impurities can significantly improve the optical quality of fluoride multicomponent crystals in the short-wavelength spectral region. 相似文献
100.
In this paper we obtain a number of Maharam-type slice integral representations, with respect to scalar measures, for positive
projections in Dedekind complete vector lattices and f-algebras.
AMS Classification: 47B65, 46A40, 06F25 相似文献