全文获取类型
收费全文 | 6121篇 |
免费 | 1021篇 |
国内免费 | 1265篇 |
专业分类
化学 | 5273篇 |
晶体学 | 76篇 |
力学 | 272篇 |
综合类 | 120篇 |
数学 | 743篇 |
物理学 | 1923篇 |
出版年
2024年 | 10篇 |
2023年 | 67篇 |
2022年 | 124篇 |
2021年 | 131篇 |
2020年 | 180篇 |
2019年 | 267篇 |
2018年 | 182篇 |
2017年 | 187篇 |
2016年 | 277篇 |
2015年 | 295篇 |
2014年 | 319篇 |
2013年 | 440篇 |
2012年 | 486篇 |
2011年 | 462篇 |
2010年 | 459篇 |
2009年 | 369篇 |
2008年 | 475篇 |
2007年 | 410篇 |
2006年 | 386篇 |
2005年 | 368篇 |
2004年 | 330篇 |
2003年 | 359篇 |
2002年 | 497篇 |
2001年 | 453篇 |
2000年 | 282篇 |
1999年 | 179篇 |
1998年 | 102篇 |
1997年 | 54篇 |
1996年 | 52篇 |
1995年 | 33篇 |
1994年 | 24篇 |
1993年 | 14篇 |
1992年 | 22篇 |
1991年 | 33篇 |
1990年 | 18篇 |
1989年 | 9篇 |
1988年 | 15篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1975年 | 1篇 |
1936年 | 2篇 |
排序方式: 共有8407条查询结果,搜索用时 15 毫秒
81.
82.
83.
Yang LI Yu ZHANG Xiao Long WANG Zhi HUANG Xiao Ping CAOState Key Laboratory of Applied Organic Chemistry College of Chemistry Chemical Engineering Lanzhou University Lanzhou 《中国化学快报》2004,(6)
A convenient and rapid approach for the synthesis of piperamide alkaloids la ~ h by the recently developed one-flask Ramberg-Backlund reaction was described. The synthesis of 1e was reported for the first time. 相似文献
84.
In the degassing process of transformer oil with ultrasonic waves ,decompostition of the oil was observed.Light hydrocarbons,including methane,ethane,ethylene ,aceylene,propane etc,were found to be released continuously from the oil into headspace within a closed vial placed in an ultrasonic field ,The gases came from decomposition of hydrocarbon molecules under cavitation effect. 相似文献
85.
Yonghong Wen Zhi Qin Weisheng Liu 《Journal of Radioanalytical and Nuclear Chemistry》2001,250(2):285-289
The extraction of Am3+ and Eu3+ from aqueous picric acid solution by N, N-dinaphthyl-N, N-diphenyl-3,6-dioxaoctanediamide (LI) and 1, 1-(3, 6, 9-trioxaundecanedionyl)diphenothiazine (LII) was investigated by a radioactive tracer technique. Extraction distribution ratios of Am3+ and Eu3+ have been measured as a function of pH, picric acid concentration, extractant concentration, diluent and temperature. The extraction of Am3+ is preferred to that of Eu3+ for both LI and LII, and the latter gives larger separation factor than the former. The equilibrium constants and thermodynamic parameters of extraction reactions were also calculated. 相似文献
86.
The properties of the triplet excited state of [60] fullerene-containing cyclic sulphoxide have been investigated by time-resolved absorption spectroscopy. Transient absorption bands of [60] fullerene-containing cyclic sulphoxide showed two decay-components, which wrer attributed to triplet excited states of different spin multiplicity. The properties of photoexcited states of [60] fullerene-containing cyclic sulphoxide are also reported. 相似文献
87.
首次合成了喹喔啉-2,3-二甲酰胺(Qxda)与3d过渡金属的三种固体配合物:M(Qxda)2cl2(M=Co(I),Ni(I),Cu(Ⅱ)。通过元素分析,摩尔电导,红外光谱,电子光谱,磁化率,热分析等手段对配合物的组成和性质进行了研究。 相似文献
88.
89.
90.
Chen Xia DU Zhi Qiang WANG Qi XIN Yang Jie WU Wen Lian LI Department of Chemistry Zhengzhou University Zhengzhou Changchun institute of optics Fine Mechanics Physics Chinese Academy of Sciences Changchun 《中国化学快报》2005,(5)
In recent years, the interest in developing luminescent lanthanide complexes has been greatly stimulated by their potential use in electroluminescent displays1. Europium complexes appear most attractive in view of the high photoluminescent efficiency and the high monochromatic red light that are widely exploited in full-color displays2. It has been approved that the second ligand plays an important role in europium complexes, the synergistic complexation of the second ligand can not only lead … 相似文献