全文获取类型
收费全文 | 81135篇 |
免费 | 12162篇 |
国内免费 | 8429篇 |
专业分类
化学 | 56149篇 |
晶体学 | 793篇 |
力学 | 5251篇 |
综合类 | 671篇 |
数学 | 9959篇 |
物理学 | 28903篇 |
出版年
2024年 | 168篇 |
2023年 | 1586篇 |
2022年 | 2251篇 |
2021年 | 2636篇 |
2020年 | 3011篇 |
2019年 | 2968篇 |
2018年 | 2557篇 |
2017年 | 2253篇 |
2016年 | 3521篇 |
2015年 | 3570篇 |
2014年 | 4213篇 |
2013年 | 5598篇 |
2012年 | 6892篇 |
2011年 | 7110篇 |
2010年 | 4874篇 |
2009年 | 4739篇 |
2008年 | 5019篇 |
2007年 | 4533篇 |
2006年 | 4208篇 |
2005年 | 3683篇 |
2004年 | 3012篇 |
2003年 | 2427篇 |
2002年 | 2338篇 |
2001年 | 2117篇 |
2000年 | 1759篇 |
1999年 | 1871篇 |
1998年 | 1506篇 |
1997年 | 1330篇 |
1996年 | 1358篇 |
1995年 | 1183篇 |
1994年 | 1084篇 |
1993年 | 934篇 |
1992年 | 839篇 |
1991年 | 746篇 |
1990年 | 621篇 |
1989年 | 518篇 |
1988年 | 399篇 |
1987年 | 367篇 |
1986年 | 318篇 |
1985年 | 320篇 |
1984年 | 219篇 |
1983年 | 182篇 |
1982年 | 147篇 |
1981年 | 114篇 |
1980年 | 83篇 |
1978年 | 56篇 |
1977年 | 52篇 |
1976年 | 50篇 |
1975年 | 57篇 |
1973年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
811.
甲苯胺蓝指示反应动力学光度法测定痕量钌 总被引:8,自引:0,他引:8
在磷酸和热水浴中 ,钌 (Ⅲ )对高碘酸钾氧化甲苯胺蓝的反应具有催化作用 ,据此建立了测定钌的新催化光度法。钌在 0~ 0 .0 5 0 μg/ 2 5ml范围内与催化反应速率有良好的线性关系 ,检出限为 5 .5 3× 10 - 5μg·ml- 1。对 0 .0 30 μg/ 2 5ml钌 (Ⅲ )测定的相对标准偏差为 2 .0 % (n =11)。该催化反应对钌 (Ⅲ )和甲苯胺蓝分别为一级反应 ,其表观活化能为 5 0 .2 6kJ·mol- 1。试验了 4 0多种共存离子的影响 ,大多数的常见离子不干扰。该方法用于岩矿和冶金产品中钌的测定 ,相对标准偏差为 2 .1%~ 2 .4 % ,标准加入回收率为 10 0 .1%~ 10 5 .4 %。 相似文献
812.
电化学超级电容器电极材料的研究进展 总被引:9,自引:0,他引:9
回顾了电化学超级电容器电极材料的研究进展,并对不同电极材料的储能原理和性能特点进行了简要的阐述。参考文献29篇。 相似文献
813.
814.
A new fluorescent compound based on calix[4] arene skeleton was synthesized.Its complexation ability with transition metal ions,such as Fe^3 ,Co^2 ,Ni^2 ,Cu^2 ,Zn^2 and Ag^ ,Was investigated by UV-vis and fluorescent spectra. 相似文献
815.
An ordinary plating solution for indium hexacyanoferrate (InHCF) thin film deposition, mainly composed of equal concentrations
of In3+ and [Fe(CN)6]3–, usually forms precipitates rapidly when either concentration is higher than few millimolar. This contributes to the plating
solution's instability. Moreover, electrodeposited capacities are limited accordingly. In this work, the plating solution's
stability and the electrodeposition of InHCF were greatly enhanced by adding a large amount of K+ and/or H+. It was found that a 10-mM plating solution added with 1 M HCl and 1 M KCl could be stored as fresh over a one-week period,
whereas an unmodified plating solution became useless within a couple of minutes. Also, such cationic additions, especially
adding H+, increased the electrodeposited capacity ca. 18 times at least, as compared with that obtained from the unmodified plating
solution. Furthermore, related enhancing mechanisms were proposed and verified. To sum up, this study offers a means for better
InHCF electrodeposition and should promote the applications of InHCF films.
Electronic Publication 相似文献
816.
综述了1β-Methyl Carbapenem中间体的合成方法,重点强调了如何构筑1位β构型的甲基。参考文献37篇。 相似文献
817.
Comprehensive two-dimensional liquid chromatographic separation by means of a combination of ion-exchange chromatography (IEC)
and reversed-phase liquid chromatography (RPLC) has been realized and applied to the analysis of components of a traditional
Chinese medicine Flos Lonicera. In the first dimension the components of a Flos Lonicera extract is separated on strong anion-exchange (SAX) column according to the charge-exchange properties of the components.
In the second dimension the components are further fractionated by reversed-phase liquid chromatography (on ODS) on the basis
of their hydrophobicity. The RPLC effluent is desalted and split and the components are identified on-line by use of both
diode-array detection and mass spectrometry with atmospheric pressure chemical ionization (APCI–MS). In this way, the extract
of Flos Lonicera can be rapidly separated, desalted, and analyzed, with determination of molecular weight. More than 58 components of an extract
of Flos Lonicera were well resolved and six were tentatively identified from their UV and mass spectra. 相似文献
818.
819.
820.
Synthesis and Characterization of Novel Orange-emitting Iridium(Ⅲ) Complexes with Diphenylquinoline Ligands Containing Fluorinated Substituent 总被引:1,自引:0,他引:1
Xiao Wei ZHANG Chu Luo YANG Zhong An LI Lin Na ZHU Jin Gui QIN Jia GAO Dong Ge MA 《中国化学快报》2006,17(3):411-414
Three new cyclometalated iridium(m) complexes based on ligands of diphenylquinoline with fluorinated subsfituents were prepared, and characterized by elemental analysis (EA), ^1H NMR, and mass spectroscopy (MS). The photophysical and electrophosphorescent properties of the complexes were briefly discussed. 相似文献