全文获取类型
收费全文 | 287篇 |
免费 | 76篇 |
国内免费 | 12篇 |
专业分类
化学 | 265篇 |
晶体学 | 10篇 |
物理学 | 100篇 |
出版年
2023年 | 1篇 |
2022年 | 9篇 |
2021年 | 11篇 |
2020年 | 18篇 |
2019年 | 18篇 |
2018年 | 21篇 |
2017年 | 10篇 |
2016年 | 18篇 |
2015年 | 24篇 |
2014年 | 15篇 |
2013年 | 19篇 |
2012年 | 19篇 |
2011年 | 12篇 |
2010年 | 12篇 |
2009年 | 17篇 |
2008年 | 19篇 |
2007年 | 20篇 |
2006年 | 26篇 |
2005年 | 12篇 |
2004年 | 12篇 |
2003年 | 13篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 8篇 |
1997年 | 5篇 |
1996年 | 1篇 |
1995年 | 6篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1985年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有375条查询结果,搜索用时 31 毫秒
41.
We synthesized melemium hydrogensulfate H3C6N7(NH2)3(HSO4)3 by reaction of melem with 70 % sulfuric acid. The crystal structure was elucidated by single‐crystal XRD (P21/n (no. 14), Z = 4, a = 10.277(2), b = 14.921(3), c = 11.771(2) Å, β = 99.24(3)°, V = 1781.5(6) Å3). H3C6N7(NH2)3(HSO4)3 is the first compound displaying a triple protonation of melem., In this contribution an overview of accessible melemium sulfates depending on the concentration of sulfuric acid is given. Two additional melemium sulfates were identified this way. 相似文献
42.
A. Stork C. Wessel A. Börger K.-D. Becker M. Lerch 《Journal of solid state chemistry》2010,183(9):2051-2058
The aim of our study was to modify the basis compound ß-TaON, which crystallizes in the monoclinic baddeleyite-type, by incorporation of appropriate dopant ions, in order to obtain anion-deficient cubic fluorite-type phases, which are of interest as solids with mobile nitrogen ions. For this purpose, scandium-doped tantalum oxide nitrides were prepared by ammonolysis of amorphous oxide precursors. An unexpected variety of phases with different structural features was observed: bixbyite-type phases of general composition ScxTa1−x(O,N)y with 0.33≤x≤1 and 1.7≤y≤1.9, yellow colored metastable anatase-type phases such as Sc0.1Ta0.9O1.2N0.8 or Sc0.15Ta0.85O1.3N0.7 and, additionally, anosovite-type phases ScxTa3−xO2xN5−2x with 0≤x≤1.05. Selected phases were investigated by UV/vis spectroscopy. Anatase- and anosovite-type compounds show brilliant colors. In the anatase-type phase, a possible anion ordering was examined by theoretical methods. Additionally, energy calculations on phase stability were performed for ScxTa1−xO1+2xN1−2x in the baddeleyite, rutile, and anatase structure types with varying amounts of dopants. 相似文献
43.
44.
B. V. Beznosikov 《Journal of Structural Chemistry》2003,44(5):885-888
Crystal-chemical analysis of the structures of perovskite-like nitrides has been carried out. For cubic phases, the geometrical regions of existence and the most probable compositions have been determined. More than 80 new compounds have been predicted. 相似文献
45.
Alexey Marchuk Prof. Dr. Wolfgang Schnick 《Angewandte Chemie (International ed. in English)》2015,54(8):2383-2387
Illumination sources based on phosphor‐converted light emitting diode (pcLED) technology are nowadays of great relevance. In particular, illumination‐grade pcLEDs are attracting increasing attention. Regarding this, the application of a single warm‐white‐emitting phosphor could be of great advantage. Herein, we report the synthesis of a novel nitridophosphate zeolite Ba3P5N10Br:Eu2+. Upon excitation by near‐UV light, natural‐white‐light luminescence was detected. The synthesis of Ba3P5N10Br:Eu2+ was carried out using the multianvil technique. The crystal structure of Ba3P5N10Br:Eu2+ was solved and refined by single‐crystal X‐ray diffraction analysis and confirmed by Rietveld refinement and FTIR spectroscopy. Furthermore, spectroscopic luminescence measurements were performed. Through the synthesis of Ba3P5N10Br:Eu2+, we have shown the great potential of nitridophosphate zeolites to serve as high‐performance luminescence materials. 相似文献
46.
47.
48.
D. Hanžel A.C. Agudelo J.R. Gancedo M. Lakatos-Varsanyi J.F. Marco 《Hyperfine Interactions》1998,111(1-4):93-100
The corrosion properties of single layered TiN and CrN films have been compared to bi-layered and multi-layered Ti/TiN films. XPS has showed that in humid SO2 atmosphere the best corrosion properties have been achieved by a multi-layered Ti/TiN coating. Cyclic voltammetry in acetate buffer has been applied to measure the porousity and corrosion resistance of coatings. The best results have been achieved by multi-layered Ti/TiN and CrN films. Conversion electron Mössbauer spectroscopy has been used to study the changes in the interface Fe/TiN during thermal treatment in UHV. It has been shown that the amount of iron nitrides in the interface increases with increasing temperature. 相似文献
49.
The luminescence properties of lanthanum silicon oxynitride(La-Si-O-N) series doped by trivalent Ce ions have been investigated to seek for tunable wavelength-conversion phosphor for white light emitting diode applications.Four compound hosts of LaSiO2N,La4Si2O7N2,La5Si3O12 N,and La2Si6O3N8 were synthesized and examined in this work.Crystallographic examination for the equal amount of Ce 3+ substitution indicated that the covalency degree decreased in a sequence LaSiO2 N > La2Si6O3N8 > La4Si2O7N2 > La5Si3O12 N,not simply in correlation to the ratio of N3/O2.Excitation and emission spectrum measurements showed the main features of Ce3+ luminescence in the series:the centre of gravity of 5d bands depends on crystal-field splitting more strongly than that on covalency of Ce-N bonding;nephelauxetic effect could not be observed clearly for the investigated series;to some extent Stokes shift was dominated by crystal-field splitting rather than Ce-N covalency degree. 相似文献
50.