全文获取类型
收费全文 | 242627篇 |
免费 | 3879篇 |
国内免费 | 639篇 |
专业分类
化学 | 134689篇 |
晶体学 | 2814篇 |
力学 | 8974篇 |
综合类 | 12篇 |
数学 | 27310篇 |
物理学 | 73346篇 |
出版年
2021年 | 1941篇 |
2020年 | 2494篇 |
2019年 | 2611篇 |
2018年 | 2930篇 |
2017年 | 2953篇 |
2016年 | 4843篇 |
2015年 | 3349篇 |
2014年 | 4785篇 |
2013年 | 11585篇 |
2012年 | 8713篇 |
2011年 | 10672篇 |
2010年 | 7125篇 |
2009年 | 6826篇 |
2008年 | 9443篇 |
2007年 | 9242篇 |
2006年 | 8706篇 |
2005年 | 7839篇 |
2004年 | 6960篇 |
2003年 | 6245篇 |
2002年 | 5964篇 |
2001年 | 6889篇 |
2000年 | 5302篇 |
1999年 | 4025篇 |
1998年 | 3211篇 |
1997年 | 3085篇 |
1996年 | 2928篇 |
1995年 | 2836篇 |
1994年 | 2723篇 |
1993年 | 2646篇 |
1992年 | 3178篇 |
1991年 | 2975篇 |
1990年 | 2952篇 |
1989年 | 2878篇 |
1988年 | 2936篇 |
1987年 | 2930篇 |
1986年 | 2764篇 |
1985年 | 3657篇 |
1984年 | 3630篇 |
1983年 | 2873篇 |
1982年 | 3015篇 |
1981年 | 3088篇 |
1980年 | 2823篇 |
1979年 | 3123篇 |
1978年 | 3148篇 |
1977年 | 3272篇 |
1976年 | 3076篇 |
1975年 | 2802篇 |
1974年 | 2728篇 |
1973年 | 2698篇 |
1968年 | 1842篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
V. V. Panić A. B. Dekanski S. K. Milonjić V. B. Mišković-Stanković B. Ž. Nikolić 《Russian Journal of Electrochemistry》2006,42(10):1055-1060
Electrocatalytic properties of RuO2/Ti anode with different coating masses, which are prepared by the alkoxide sol-gel procedure, are investigated in chlorine
and oxygen evolution reactions by polarization measurements and electrochemical impedance spectroscopy in H2SO4 and NaCl electrolytes. According to polarization measurements, the activity of anodes at overpotentials below 100 mV is independent
of coating mass. However, impedance measurements above 100 mV reveal changes in the activity of anodes in chlorine evolution
reaction for different coating masses. The diffusion limitations related to the evolved chlorine are registered in low-frequency
domain at 1.10 V (SCE), diminishing with the increase in potential to the 1.15 V (SCE). The observed impedance behavior is
discussed with respect to the activity model for activated titanium anodes in chlorine evolution reaction involving formation
of gas channels within porous coating structure. Gas channels enhance the mass transfer rate similarly to the forced convection,
which also increases the activity of anode. This is more pronounced for the anode of greater coating mass due to its more
compact surface structure. The more compact structure appears to be beneficial for gas channels formation.
Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 10, pp. 1173–1179.
The text was submitted by the authors in English. 相似文献
992.
The mechanism of X-ray waveguide-resonance propagation or the radiation superstream model, which can become the ground of X-ray nanophotonics, is discussed briefly. Some attention is devoted to features consideration of the simplest devices characterized by the waveguide-resonance transportation of X-ray beams. The experimental data showing the user possibilities of a simplest waveguide-resonators application for diffractometry are presented. We discuss the main reasons to improve the metrological characteristics for total reflection X-ray fluorescence (TXRF) analytical method in case when the target exciting beam is formed by a waveguide-resonator. Some problems appearing during the waveguide-resonator application are formulated. 相似文献
993.
994.
Summary A non-destructive method is described for the determination of major and minor constituents in archeological specimens by energy-dispersive X-ray fluorescence. Homogeneity tests are made by measuring at various sites of the specimen. In the same way, mean values are obtained for inhomogeneous specimen without taking samples. For calibration, powder standards are used. In case of the determination of elements with numbers up to 14 (Si) a vacuum chamber is used and the dimensions of the specimens are limited by the dimensions of that vacuum chamber, whereas for the determination of elements from K up to U specimens of any size, form or weight are suitable.
Zerstörungsfreie Analyse von archäologischen Proben mit Hilfe der Energie-dispersiven Röntgenfluorescenzanalyse
Zusammenfassung Eine zerstörungsfreie Methode für die Bestimmung von Haupt- und Nebenbestandteilen in archäologischen Proben mit Hilfe der Energie-dispersiven Röntgenfluorescenzanalyse wird beschrieben. Für Homogenitätstests wird an mehreren Stellen der Probe gemessen. In der gleichen Weise werden für inhomogene Proben Mittelwerte erhalten ohne Probenahme. Für die Eichung werden Pulverstandards verwendet. Im Falle der Bestimmung von Elementen mit Ordnungszahlen bis 14 (Si) wird eine Vakuumkammer eingesetzt, und die Dimensionen der Proben sind durch die Dimensionen dieser Vakuumkammer begrenzt, während für die Bestimmung der Elemente K bis U Proben jeder Größe, jeder Form oder jeden Gewichts verwendbar sind.相似文献
995.
J. Bartella K. Kastner K. Röll und K. -H. Schuller 《Fresenius' Journal of Analytical Chemistry》1987,329(2-3):289-291
Summary Besides functional behaviour of coatings their resistivity against corroding attack is a crucial criterion for quality. The application of special corroding and abrading tests yields after short times predictions about stability of the product in practical use. A number of tests have been applied to thin magnetic storage media. Besides tests of function and visual observations with light- and scanning electron microscopes, AES- and XPS-investigations were applied to discuss corrosion resistivity. 相似文献
996.
997.
998.
999.
K. Stein und F. Umland 《Fresenius' Journal of Analytical Chemistry》1986,323(2):176-177
Ohne Zusammenfassung
Wir danken dem Fonds der Chemischen Industrie für finanzielle Unterstützung. 相似文献
Trace analysis of lead, cadmium and manganese in honey and sugar
Wir danken dem Fonds der Chemischen Industrie für finanzielle Unterstützung. 相似文献
1000.
We study applications of the theory of quadratic differentials to the solution of new extremal problems of nonoverlapping
domains with free poles on rays and generalize known results to a certain class of open sets.
__________
Translated from Neliniini Kolyvannya, Vol. 10, No. 4, pp. 435–442, October–December, 2007. 相似文献